USE OF MIR-223-3P AS A CANCER THERAPEUTIC AND METHOD FOR TREATING CANCER USING THE SAME

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Serial No. 62/322,295, filed April 14, 2016, the disclosure of which is hereby incorporated by reference in its entirety, including all figures, tables and amino acid or nucleic acid sequences.

This invention was made with government support under GM109645 awarded by the

National Institutes of Health. The government has certain rights in the invention.

The Sequence Listing for this application is labeled "Seq-List.txt" which was created on April 13, 2017 and is 32 KB. The entire content of the sequence listing is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Some cancers, most commonly breast, ovarian, prostate and pancreatic cancers, have mutations in genes that mediate homologous recombination DNA repair, such as BRCA1 or 2. These mutations are often inherited and therefore, such cancers occur in familially related patients. Due to the defect in homologous recombination DNA repair, the cancer cells in these cancers depend on other DNA repair pathways.

BRIEF SUMMARY OF THE INVENTION

The invention exploits the reliance of cancer cells having mutations in the genes that mediate homologous recombination DNA repair on other DNA repair pathways to treat these cancers (e.g., BRCA1 and/or BRCA2). The invention provides the use of an inhibitory RNA (iRNA) that mediates sequence-specific degradation of the mRNA encoding Poly (ADP- ribose) polymerase 1 (PARPl) as a novel therapeutic agent for treating cancer. Since normal cells can tolerate reductions in PARPl activity, this approach does not have side effects. The iRNA can be a small inhibitory RNA (siRNA), microRNA (miRNA), short hairpin RNA (shRNA) or antisense-oligonucleotide. In one embodiment, the iRNA is an miRNA, preferably, miR-223, more preferably, miR-223-3p or a modified miR-223-3p having substitutions and/or deletions in miR-223-3p. Accordingly, the invention provides a pharmaceutical composition comprising the iRNA, preferably, an miRNA, more preferably, miR-223-3p or a modified miR-223-3p.

A method of treating cancers having mutations in the genes that mediate homologous recombination DNA repair are also provided. The method comprises administering the pharmaceutical composition of the invention to a subject in need thereof. The cancer can be breast cancer, ovarian cancer, prostate cancer, pancreatic cancer or mesothelioma. Methods of treating cancer using a combination of the iRNA of the invention and a second cancer therapeutic are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1. Colony Formation Survival Assay. BRCA1 mutant cancer cell lines

MDA-MB-436 (breast cancer) and UWB 1.289 (ovarian cancer), deficient in BRCA1 showed decreased number of colonies when cells were treated with 25 nm miR-223-3p mimic. * indicates p = 0.009 and ** indicates p = 0.000096.

Figure 2. Western analysis of PARPl after exposure to miR-223-3p mimic. miR-

223-3p represses PARPl protein expression in the breast and ovarian cell lines harboring

BRCA1 mutant.

Figure 3. Endogenous levels of miR-223 in HL60 cells following 50 μΜ AraC. qRT-PCR of miR-223-3p: The levels of endogenous miR-223-3p decrease at different time points after treating the cells with 50 μΜ Ara-C. NT - non-treated (left). Western blot analysis showing inverse correlation of PARPl protein with miR-223 at different time points after Ara-C treatment. Ara-C stalls replication forks, which collapses and generates onesided DNA ends, requiring DNA repair. Thus, miR-223-3p levels decrease upon DNA damage, when PARPl is required to promote DNA repair.

Figure 4. Alternative Non-Homologous End Joining (aNHEJ) in EJ2-GFP cells. Mir223-3p blocks aNHEJ - aNHEJ is a salvage DNA repair pathway that requires PARPl . EJ2 cells express GFP upon productive aNHEJ repair (the assay is initiated with expression of transduced Isce-I). The fraction of EJ2 cells with productive aNHEJ is decreased with prior exposure to miR-223-3p (left). This pathway can lead to dangerous genomic rearrangements such as chromosomal translocations. Thus, many normal cells may express miR-223-3p to regulate this pathway. Figure 5. Mir223a reduces PARPl 3' UTR mRNA levels - The 3' UTR of PARPl mRNA (ENST0000036) was linked to Firefly Luciferase. When this RNA is present the cells will express Luciferase, but when miR-223-3p is present the Luciferase expression is decreased. This indicates that miR-223-3p binds to and mediates the destruction of PARPl mRNA.

Figure 6. Sequence alignment of Mir-223-3p (SEQ ID NO: 75) with 3' UTR of PARPl mRNA (SEQ ID NO: 92).

Figure 7. Mature miR-223-3p underlined within the miR-223 pre-microRNA structure.

Figure 8. Novel gain of function mutations in mir-223-3p to improve its repression of PARPl . Each derivative will have the corresponding nucleotide alteration in 5p strand as well. Modifications are bolded and underlined. Deletions are indicated by

Figures 9-22. Novel miR-223 -3 p derivatives 1 to 14 having enhanced PARPl repression. The substitutions and/or deletions are underlined.

Figure 23. Human mesothelioma cells treated with 3 μΜ olaparib for 10 days. The graph shows the average from 3 independent experiments each done in triplicates.

Figures 24A-24B. Figure 24A. Colony formation assay in Human Mesothelioma Cells-1 in the presence of different PARPl inhibitors. Figure 24B. Western blot analysis showing reduced expression of PARPl in response to the inhibitors.

Figures 25A-25B. Expression of miR223-3p mimic in cells (Figure 25A) and repression of PARPl using a miR223 mimic (Mir223-3p; Figure 25B).

Figures 26A-26B. Construct (Figure 26A) and assay results (Figure 26B) for miR223-3p mimic induced inhibition of PARPl using a luciferase reporter system.

Figures 27A-27B. HR defecient cells express repressed levels of miR223-3p. Endogenous levels of miR223 3p and 5p in HR deficient cells was compared to Jurkat cells. Figure 27A depicts the relative fold change in expression and endogenous levels are shown in Figure 27B.

Figure 28 compares the levels of miR223-5p and miR223-3p in cells.

Figures 29A-29D. Reconstitution of miR223-3p is toxic to BRCA1 -deficient cancer cells. In a colony formation assay, cell lines MDA-MB-436 (Figure 29A) and UWB 1.289 (Figure 29B), deficient in BRCA1, show decreased number of colonies when cells are treated with mir223 mimic (miR223-3p). Colony formation is shown in Figure 29C and Figure 29D shows knockdown of PARPl in a Western blot. Figures 30A-30B. Toxicity of cells due to loss/inhibition of PARPl . Cells were treated with 50nM siPARP or 25 nM miR223-3p (Figure 30A). Cells treated with 3uM Olaparib continuously for 15 days (Figure 30B).

Figures 31A-31D. Colony formation of cells treated with olaparib (Figures 31A and 3 IB) and miR223-3p (Figure 3 ID). Figure 31C illustrates the numbers of colonies formed when treated with olaparib.

Figures 32A-32C. Synthetic lethality in BAPl mutant mesothelioma (colony formation assays (Figures 32A-32B) and knockdown of PARPl by miR223-3p (Figure 32C).

Figures 33A-33C. Effect of miR223-3p on DNA damage (Figures 33A and 33B). 25nM of either the scr or miR223-3p mimic were transfected into cells 72 hours after transfection, the cells are fixed and stained with DAPI. Knockdown of PARPl by miR223- 3p (Figure 33C).

Figure 34. Effect of miR223-3p on DNA damage.

Figure 35. miR223-3p decreases active replication forks in MDA-MB-436 BRCA mutant cells. Cells were transfected with miRNA, seventy -two hours later, the cells were treated with 30 micromolar BrdU for 30 minutes and then fixed and stained.

Figures 36A-36C. Decreased active replication forks in H2452 BAPl mutant cells. Figures 36A-36B show representative images and percentage of active replication forks as measured by BrdU (assays as mentioned in Figure 35). Figure 36C shows PARPl knockdown in the cells.

Figure 37. DNA fiber analysis showing defective replication fork restart

Figures 38A-38B. Measuring the levels of endogenous miR223-3p (qRT-PCR) in MCF7 cells after treating the cells with siRNA for BRCA1 (Figure 38A). Western blots show BRCA1 knockdown (Figure 38B).

Figures 39A-39B. Effect of miR223-3p on aNHEJ in EJ2-GFP cell reporter system

(percent GFP positive cells (Figure 39A) and Western blot showing knockdown of PARPl (Figure 39B).

Figures 40A-40B and 41. Metaphase spreads in Jurkat cells. Different chromosomal translocation events such as ring chromosome, dicentric chromosome, double minutes and cruciform structures were counted and quantitated individually (Figures 40A, 40B and 41).

Figures 42A and 42B. miR223-3p is a global regulator of genomic stability. qRT- PCR showing gradual decrease in the levels of endogenous miR223 at different time points after treating the cells with 50uM Ara-C (NT-non-treated; Figure 42A). Western blot showing inverse correlation of PARP1 protein with miR223-3p at different time points after Ara-C treatment (Figure 42B).

Figure 43. Mirr223-3p depletes other DNA repair components as well as PARP1. MDA MB 436, HCC 1937 and H2452 cells were transfected with scr control and miR223-3p mimic. Cells were collected after 48 hours. From left to right, Lane 1 : MDA scr; Lane 2: MDA mimic; Lane 3 : 1937 scr; Lane 4: 1937 mimic; Lane 5 : H2452 scr; Lane 6: H2452 mimic.

Figure 44. Gain of function mutant for mir-223-3p (SEQ ID NO: 93). The "-" represents a deleted nucleotide within the wild type miR223-3p.

DETAILED DISCLOSURE OF THE INVENTION

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising". The transitional terms/phrases (and any grammatical variations thereof) "comprising", "comprises", "comprise", "consisting essentially of, "consists essentially of, "consisting" and "consists" can be used interchangeably.

"Treatment", "treating", "palliating" and "ameliorating" (and grammatical variants of these terms), as used herein, are used interchangeably. These terms refer to an approach for obtaining beneficial or desired results including but not limited to therapeutic benefit. A therapeutic benefit is achieved with the eradication or amelioration of one or more of the physiological symptoms associated with cancer such that an improvement is observed in the patient, notwithstanding that the patient may still be afflicted with cancer.

As used herein, the term "cancer" refers to the presence of cells possessing abnormal growth characteristics, such as uncontrolled proliferation, immortality, metastatic potential, rapid growth and proliferation rate, perturbed oncogenic signaling, and certain characteristic morphological features. This includes but is not limited to the growth of: (1) benign or malignant cells (e.g., tumor cells) that correlates with overexpression of a serine/threonine kinase; or (2) benign or malignant cells (e.g., tumor cells) that correlates with abnormally high levels of serine/threonine kinase activity or lipid kinase activity. Non-limiting serine/threonine kinases implicated in cancer include but are not limited to PI-3K mTOR, and AKT. Exemplary lipid kinases include but are not limited to PI3 kinases such as PBKa, ΡΒΚβ, ΡΒΚδ, and ΡΒΚγ.

The term "effective amount" or "therapeutically effective amount" refers to that amount of a pharmaceutical described herein that is sufficient to effect the intended application including but not limited to cancer treatment. The therapeutically effective amount may vary depending upon the intended application, the subject and cancer being treated, e.g., the weight and age of the subject, the type and severity of cancer, the manner of administration and the like. A therapeutically effective amount can be readily determined by one of ordinary skill in the art. The term also applies to a dose that will induce a particular response in target cells, e.g., reduction of proliferation or downregulation of activity of a target protein. The specific dose will vary depending on the particular compounds chosen, the dosing regimen to be followed, whether it is administered in combination with other compounds, timing of administration, the tissue to which it is administered, and the physical delivery system in which it is carried.

A "sub-therapeutic amount" of an agent is an amount less than the effective amount for that agent, but which when combined with an effective or sub-therapeutic amount of another agent or therapy can produce a desired result, due to, for example, synergy in the resulting efficacious effects (e.g., therapeutic benefit) for the patient, or reduced side effects associated with the compounds administered to the patient. Typical therapeutic amounts for an agent, as disclosed herein, can be ascertained from various publicly available sources (e.g., drugs.com, The Physician's Desk Reference, or scientific literature). Sub-therapeutic amounts of an agent, as provided herein, are amounts less than those reported in the publicly available sources for treatment of a particular cancer. Sub-therapeutic amounts of an therapeutic agent are, therefore, between about 10%-75%, about 20-50%, about 35-65%, about 40-60%), about 45-55%> or about 50% of the standard therapeutic amount of a given therapeutic agent.

"Pharmaceutically acceptable carrier" or "pharmaceutically acceptable excipient" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the pharmaceutical compositions described herein, its use in the compositions of the invention is contemplated. A "subject" refers to an animal, such as a mammal, for example a human. The methods described herein can be useful in both humans and non-human animals. In some embodiments, the subject is a mammal, such as an animal model of disease, for example, a rodent, cattle, pig, rabbit, dog or cat and in some embodiments, the subject is a human. The terms "subject" and "patient" can be used interchangeably.

The terms "co-administration," "administered in combination with," and their grammatical equivalents encompass administration of two or more therapeutics to a subject so that both agents and/or their metabolites are present in the subject at the same time. Coadministration includes simultaneous administration in separate compositions, administration at different times in separate compositions, or administration in a composition in which both pharmaceutics are present.

Accordingly, an embodiment of the invention provides a pharmaceutical composition comprising an iRNA that mediates sequence-specific degradation of an mRNA encoding PARPl . In one embodiment, the subject being treated is a human and the mRNA encoding PARPl has the sequence of SEQ ID NO: 1; whereas, the sequence of PARPl protein has the sequence of SEQ ID NO: 2. The sequences of the mRNAs encoding PARPl protein in other mammals are publically available, for example, in NCBI and other sequence databases, and such embodiments are within the purview of the invention.

In one embodiment, the iRNA is an siRNA. The siRNA can have the combinations of antisense and sense strand sequences as shown in Table 1 below. In one embodiment, the siRNA has 3' overhang of one or more nucleotides, preferably, one or two deoxy thy mi dines. In another embodiment, the siRNA is chemically modified in a manner that decreases the susceptibility of nucleic acids to nuclease degradation and/or reduces an innate immune response to the siRNA. Non-limiting examples of such chemical modifications include 2'- deoxy, 2'-0-methyl, 2'-fluoro, 2'-methoxyethyl, or 2'-aminoethyl modifications, such as those disclosed in U.S. Patent No. 9,222,092 which is hereby incorporated by reference in its entirety. Table 1. siRNAs that mediate degradation of an mRNA of SEQ ID NO: 1.

In another embodiment, the iRNA is an shRNA. An shRNA can have the combinations of antisense and sense sequences as shown in Table 2 below. A person of ordinary skill in the art can design an shRNA based on the antisense and sense strand sequences as provided below, for example, by adding appropriate loop sequences between the sense and the anti-sense sequences. In one embodiment, an shRNA is encoded by a vector containing the shRNA encoding sequence. Methods of designing shRNA and vectors containing shRNA encoding sequences are well known to a person of ordinary skill in the art and such embodiments are within the purview of the invention.

Table 2. shRNAs that mediate degradation of an mRNA of SEQ ID NO: 1.

SEQ SEQ

shRNA

Sense strand sequence ID Antisense strand sequence ID ID NO: NO: shRNA- 1 GGAGUAUGAGAUCGACCUUCA 53 UGAAGGUCGAUCUCAUACUCC 54 shRNA-2 GCUCCUGAACAAUGCAGACAG 55 CUGUCUGCAUUGUUCAGGAGC 56 shRNA-3 GGUCUGAUGAUAGCAGCAAGG 57 CCUUGCUGCUAUCAUCAGACC 58 shRNA-4 GCAAGGAUCCCAUCGAUGUCA 59 UGACAUCGAUGGGAUCCUUGC 60 shRNA-5 GCAACCACACACAAUGCGUAU 61 AUACGCAUUGUGUGUGGUUGC 62 shRNA-6 GCGUAUGACUUGGAAGUCAUC 63 GAUGACUUCCAAGUCAUACGC 64 shRNA-7 GCCAGCGUUACAAGCCCUUUA 65 UAAAGGGCUUGUAACGCUGGC 66 shRNA-8 GCCCUUUAAGCAGCUUCAUAA 67 UUAUGAAGCUGCUUAAAGGGC 68 shRNA-9 GGAUCUAUUUCGCUGACAUGG 69 CCAUGUCAGCGAAAUAGAUCC 70 shRNA- GCCAACUACUGCCAUACGUCU AGACGUAUGGCAGUAGUUGGC

71 72 10

In a further embodiment, the iRNA is an antisense oligonucleotide. An antisense oligonucleotide can have the sequences as shown in Tables 1 and 2 for the antisense strands. An antisense oligonucleotide can be chemically modified in a manner that decreases the susceptibility of nucleic acids to nuclease degradation. Non-limiting examples of chemical modifications to antisense oligonucleotide include adding phosphorothionate, methyl phosphonate or phosphoramidate moieties.

In one embodiment, the iRNA is an miRNA, preferably, miR-223, even more preferably, miR-233-3p. The sequence of pre-miR-223 is SEQ ID NO: 73; whereas, the sequence of miR-223-5p is SEQ ID NO: 74 and the sequence of miR-223-3p is SEQ ID NO: 75. In another embodiment, miR-223-3p is modified where one or more nucleotides of miR- 223-3p are substituted or deleted. In certain examples, the modified miR-223-3p has the sequence selected from SEQ ID NOs: 76 to 89 and 93 and are illustrated in Figure 8. In another example, the modified mir223-3p sequence is SEQ ID NO: 93, and illustrated in Figure 44.

In a further embodiment, the miRNA is chemically modified in a manner that decreases the susceptibility to nuclease degradation. Non-limiting examples of modifications to the miRNAs include uridylation, adenylation, 2'-deoxy modification, 2'-0-methylation, 2'-fluorination, 2'-methoxyethylation, 2'-aminoethylation or adding phosphorothionate, methyl phosphonate or phosphoramidate moieties.

In an embodiment, the iRNA molecules are conjugated to a carrier at the 5' or 3' end of the iRNA. The carrier can be a molecule that decreases clearance in a subject's body, for example, polymers, such as dextrans or PEG. The carrier can also be a molecule that enhance cellular uptake of the iRNA conjugated thereto, for example, transferrin or lipophilic molecules that enhance cellular uptake, such as cholesterol, short chain fatty acids, single or double chain fatty acids or folates. Further, the carrier can be a targeting molecule, such as antibodies, polypeptides, nucleic acids and other substances that direct the iRNA to selected target cells.

Furthermore, the carrier is a molecule that facilitates endocytosis of the iRNA. Non- limiting examples of carriers that facilitate endocytosis include single or double chain fatty acids, tocopherol, folates or folic acid, cholesterol, sugars such as galactose and mannose and their oligosaccharides, peptides such as RGD and bombesin, and proteins such as integrin. Non-limiting examples of molecules for improving endocytosis for use in pharmaceutical composition are described in the U.S. Patent Application Publication US2008/0194540.

Fatty acids may be saturated or unsaturated and be in C4-C28, preferably in C14-C22, still more preferably in C ₁₈ such as oleic acid or stearic acid. Fatty acids can also be octadecyl or dioleoyl. Fatty acids can be found in double chain form linked with an linker such as a glycerol, a phosphatidylcholine or ethanolamine.

As used herein, the term "folate" refers to folate and folate derivatives, including pteroic acid derivatives and analogs. The analogs and derivatives of folic acid suitable for use in the invention include, antifolates, dihydrofolates, tetrahydrofolates, folinic acid, pteropolyglutamic acid, 1-deza, 3-deaza, 5-deaza, 8-deaza, 10-deaza, 1,5-deaza, 5, 10-dideaza, 8, 10-dideaza, and 5,8-dideaza folates, antifolates, and pteroic acid derivatives. Additional folate analogs are described in the U.S. Patent Application Publication US2004/242582.

Additional examples of chemical modifications that increase siRNA, shRNA, anti sense and miRNA stability are well known to a person of ordinary skill in the art and such embodiments are within the purview of the invention. For example, the iRNA disclosed herein can contain an "end modification" which means a chemical entity is added to the most 5' and/or 3' nucleotide. Examples of such end modifications include, but are not limited to, inverted (deoxy) abasics, amino, fluoro, chloro, bromo, CN, CF, methoxy, imidazole, carboxylate, thioate, C ₁ to C ₁₀ lower alkyl, substituted lower alkyl, alkaryl or aralkyl, OCF ₃ , OCN, 0-, S-, or N-alkyl; 0-, S-, or N-alkenyl; SOCH ₃ ; S0 ₂ CH ₃ ; ON0 ₂ ; N0 ₂ , N ₃ ; heterocycloalkyl; heterocycloalkaryl; aminoalkylamino; polyalkylamino or substituted silyl, as, among others, described in European patents EP 0 586 520 Bl or EP 0 618 925 B l . As used herein, alkyl or any term comprising "alkyl" means any carbon atom chain comprising 1 to 12, preferably 1 to 6 and more, preferably 1 to 2 C atoms. A further end modification is the addition of a biotin group to the iRNA, which may preferably be attached to either the most 5' or the most 3' nucleotide or to both ends. Such a modification permits the attachment of the iRNA molecule to a polypeptide, protein or other targeting agent/substrate via avidin or streptavidin binding to the polypeptide, protein or other targeting agent.

Yet other modifications to the iRNAs disclosed herein include modification of at least one nucleotide of the iRNA at the 2' -position of nucleotides' s ribose moiety. Modification of the ribose moiety is, preferably, with a substituent selected from the group consisting of an amino, fluoro, methoxy, alkoxy and alkyl group. As used herein, alkyl or any term comprising "alkyl" means any carbon atom chain comprising 1 to 12, preferably 1 to 6 and more, preferably 1 to 2 C atoms.

The disclosed iRNA molecules can also contain patterns of modifications. For example, a contiguous stretch of nucleotides can contain modifications within a single nucleotide or group of nucleotides that are covalently linked to each other via standard phosphodiester bonds or, at least partially, through phosphorothioate bonds. In the event that such a modified nucleotide or group of modified nucleotides does not form the 5 -end or 3 - end of the stretch, a flanking nucleotide or group of nucleotides may be arrayed on one or both sides of the modified nucleotide or group, where the flanking nucleotide or group either is unmodified or is modified and does not have the same modification as the preceding nucleotide or group of nucleotides. This sequence of modified nucleotide or group of modified nucleotides, respectively, and unmodified or differently modified nucleotide or group of unmodified or differently modified nucleotides may be repeated one or more times or groups of modified nucleotides can be flanked by groups of differently modified or unmodified nucleotides. The groups of modified, unmodified or differently modified nucleotides can number between one (1) and ten (10) nucleotides. The term "unmodified nucleotide" as used herein means either not having any of the aforementioned modifications at the nucleotide forming the respective nucleotide or group of nucleotides. Modifications, such as those disclosed in U.S. Patent No. 9,222,092, which is hereby incorporated by reference in its entirety, can also be made to the iRNA disclosed herein.

In one embodiment, the iRNAs of the claimed invention, for example, the siRNAs, shRNAs, antisense oligonucleotides or miRNAs described above, are in a pharmaceutical composition, wherein the pharmaceutical composition comprises liposomes containing the iRNAs, microspheres containing the iRNAs or serum albumin complexes containing the iRNAs.

Liposomes are made of phospholipid molecules capable of encapsulating the iRNAs of the invention within the liposome aqueous core. Liposomes can be designed to protect the iRNAs in vivo. Liposomes can also be modified to enhance the delivery of iRNAs into specific target cells. For example, liposomes can be modified to contain binding agents, for example, binding proteins, antibodies or fragments of antibodies, that specifically bind to biomolecules, for example, cell surface receptors, that are specifically present on the surface of the cancer cells or that are present on the surface of the cancer cells at a higher level compared to non-target cells. Certain examples of using specific cell surface biomolecules present on the surface of the cancer cells and corresponding binding agents that can be incorporated in liposomes are described in Deshpande et al., the contents of which are herein incorporated by reference in their entirety. Additional examples of cell surface biomolecules specifically present or overexpressed on the surface of the cancer cells are known to a person of ordinary skill in the art and such embodiments are within the purview of the claimed invention. Liposomes can be administered topically, orally, or via pulmonary or parenteral routes.

Various liposome compositions are known to a person of ordinary skill in the art. For example, Maherani et al. (2011) describes manufacturing techniques for liposomes, composition of liposomes, methods of encapsulating biomolecules into liposomes, and methods of producing pharmaceutical compositions comprising liposomes. The Maherani et al. reference is herein incorporated by reference in its entirety.

In one embodiment, the liposomes contain agents that destabilize the liposome membrane and cause the release of contents in the aqueous compartment into the target cells. The destabilizing agents can destabilize the liposomes in response to a lower pH, for example, lower pH present in endosomes/lysosome compartments of the target cells. In certain embodiments, temperature sensitive or radiation sensitive destabilizers are used where the cancer cells, for example, in a tumor, can be subjected to conditions that cause release of the contents of the liposomes into the target cells.

In one embodiment, the invention provides pharmaceutical compositions comprising microspheres containing the iRNA described herein. In a specific embodiment, the microspheres are ephrin-Al loaded microspheres, particularly, ephrinAl -loaded albumin microspheres. Lee et al. (2011) describe ephrinAl -loaded albumin microspheres. The Lee et al. reference is herein incorporated in its entirety.

In another embodiment, the pharmaceutical composition of the invention comprises the iRNA of the invention, particularly, miR-223, and more particularly, miR-223-3p or a modified miR-223-3p, complexed with serum albumin.

Certain examples of serum albumin complexed with an iRNA in a pharmaceutical composition are provided in Nicoli et al. and U.S. Patent 8,513,402. Nicoli et al. and the U.S. Patent 8,513,402 are herein incorporated by reference in their entirety. Additional techniques of using serum albumin complexed with an iRNA in a pharmaceutical composition are well known to a person of ordinary skill in the art and such embodiments are within the purview of the invention.

A further embodiment of the invention provides a method of treating cancer, the method comprising administering the pharmaceutical composition described herein to a subject in need thereof. In a particular embodiment, the cancer cells of the subject comprise a mutation in one or more genes that mediate the homologous recombination DNA repair, for example, BRCA1 and/or BRCA2 genes. In additional embodiments, the cancer cells of the subject comprise a loss of function via a mutation or epigenetic silencing in one or more genes that mediate the homologous recombination DNA repair, for example, the genes provided in Table 3 :

Table 3. Genes that mediate the homologous recombination DNA repair and cancers associated with the mutation, repression or deficiency of these genes that can be treated according to the invention.

Acronym Full-name Associated cancers

BAP1 BRCA1 associated protein-1 melanoma, renal cell carcinoma, non-small cell lung cancer, cholangiocarcinoma, mesothelioma, malignant mesothelioma, uveal melanoma and cutaneous melanoma

RAD51 RAD51 recombinase breast, ovarian, and uterine cancer and acute and its myeloid leukemia, acute lymphoid paralogues leukemia, non-Hodgkin's lymphoma, and A, B and C chronic lymphocytic leukemia

MMSET multiple myeloma SET Myeloma, acute myeloid and lymphoid (NSD2) domain or Nuclear SET leukemia

Domain-Containing Protein 2

ATM Ataxia Telangiectasia Myeloma, acute myeloid and lymphoid

Mutated leukemia

ATR Ataxia Telangiectasia And endometrial, gastric cancers

Rad3 -Related Protein

CHEK2 Checkpoint Kinase 2 Breast cancer, sarcoma, brain tumor,

prostate cancer, colorectal cancer ERCC (1, Excision Repair Cross- skin basal cell cancer; skin squamous cell 2, 3, 4 or 5) Complementation Group (1, cancer; melanoma, skin cancer

2, 3, 4 or 5)

BN Nijmegen Breakage NHL, glioma, medulloblastoma,

(NBS1) Syndrome 1 rhabdomyosarcoma, breast-ovarian cancer

PALB2 Partner And Localizer Of Wilms tumour, medulloblastoma, AML,

BRCA2 breast cancer, pancreatic cancer

BACH Basic Region Leucine Zipper Breast cancer

Transcriptional Regulator

BACH

SMARCA4 SWI/S F Related, Matrix non-small cell and small cell lung cancer,

Associated, Actin Dependent breast cancer, meningioma, glioma, prostate Regulator Of Chromatin, cancer

Subfamily A, Member 4

SMARCB1 SWI/SNF Related, Matrix non-small cell and small cell lung cancer,

Associated, Actin Dependent breast cancer, meningioma, glioma,

Regulator Of Chromatin, carcinoma, medulloblastoma, choroid plexus Subfamily B, Member 1 carcinoma, central primitive

neuroectodermal tumors, renal or extra-renal malignant Rhabdoid tumors, non-vestibular schwannomas

SMARCD1 SWI/SNF Related, Matrix non-small cell and small cell lung cancer,

Associated, Actin Dependent breast cancer, meningioma, glioma, prostate Regulator Of Chromatin, cancer

Subfamily D, Member 1

SMARCE1 SWI/SNF Related, Matrix non-small cell and small cell lung cancer,

Associated, Actin Dependent breast cancer, meningioma, glioma, multiple Regulator Of Chromatin, meningioma, clear cell meningioma

Subfamily E, Member 1

WRN Werner Syndrome, RecQ Osteosarcoma, meningioma, pancreatic

Helicase-Like cancer, colorectal cancer, adenoma, invasive adenocarcinoma BLM Bloom Syndrome, RecQ Breast cancer, ovarian cancer, uterine Helicase-Like cancer, acute myeloid leukemia, acute

lymphoid leukemia, chronic lymphocytic leukemia, gliomas, medulloblastomas, basal cell carcinomas, pancreatic cancer, skin cancer, colorectal cancer

EEPD1 Endonucl ease/Exonucl ease/ colon, lung, breast cancers, and non- Phosphatase Family Domain Hodgkin's lymphoma

Containing 1

Also contemplated by this disclosure is the treatment of cancers containing functional BRCA1 and/or BRCA2 DNA repair systems. In the case of such cancers, the methods contemplate the inactivation of the BRCA1 and/or BRCA2 DNA repair systems by interfering with BRCA1 and/or BRCA2 expression (e.g. via the use of iRNA (e.g., siRNA, antisense or shRNA) to downregulate or suppress expression of BRCA1 and/or BRCA2). The BRCA1 and BRCA2 iRNA can be co-administered with the PARPl iRNA disclosed herein in order to mediate a therapeutic effect. Additional examples of the proteins involved in the homologous recombination DNA repair are well known to a person of ordinary skill in the art and such embodiments are within the purview of the claimed invention.

For the purpose of this invention, the phrase "a cancer cell comprises a mutation in one or more genes that mediate the homologous recombination DNA repair" indicates that the cancer cell contains one or mutations in one or more genes that encode for proteins that mediate the homologous recombination DNA repair and where the mutations in the genes affect the function of the encoding proteins such that the homologous recombination DNA repair does not function or functions at a lower efficiency when compared to a wild-type cell.

In some embodiments, the cancer is selected from breast cancer, ovarian cancer, prostate cancer, pancreatic cancer, lung cancer, small cell lung cancer, non-small cell lung cancer, cholangiocarcinoma, renal cell carcinoma or mesothelioma in which the BRCA1, BRCA2 and/or BAPl genes are inactive due to mutations within the genes. In specific embodiments, miR223-3p can be used for intraperitoneal or intravenous chemotherapy of homologous recombination (HR)-deficient ovarian cancer, intravenous chemotherapy of HR- deficient breast cancer, intravenous chemotherapy of IDH1 -mutant acute leukemia and glioblastoma (the IDH1 mutation represses HR DNA repair, making cancer sensitive to PARPl inhibition), intravenous or intra-pleural chemotherapy of BAP 1 -mutant mesothelioma, or intravenous chemotherapy of BAP 1 -mutant melanoma, BAP 1 -mutant cholangiocarcinoma, and BAP 1 -mutant renal cell carcinoma (the BAP-1 mutation represses HR DNA repair, making cancer sensitive to PARPl inhibition). In an embodiment, the method of treating cancer in a subject comprises administering to the subject the iRNA of the invention, for example, miR-223, miR-223-3p or a modified miR-223-3p described herein, wherein the method further comprises administering a second cancer therapy to the subject. The second cancer therapy can be selected from radiotherapy, chemotherapy, surgery, immunotherapy, monoclonal antibody therapy (e.g., bevacizumab or cetuximab) or a combination thereof.

In one embodiment, the second therapy is designed to induce DNA damage in the cell which increases the need of a cancer cell for DNA damage repair and consequently, increases the dependence of the cell on PARPl in a cell that has a defective homologous recombination DNA repair. As such, in one embodiment, the iRNA of the invention, for example, miR-223, miR-223-3p or a modified miR-223-3p described herein, is administered in combination with the second therapy that induce DNA damage in the cell. In a particular embodiment, either or both of the iRNA of the invention and the second therapy designed to induce DNA damage in the cell are administered in a sub-therapeutic amount.

Non-limiting examples of the second therapy that induce DNA damage in a cell includes one or more of the following drugs: adriamycin, cytarabine, daunorubicin, idarubicin, cisplatin, oxaliplatin, carboplatin, irinotecan, camptothecin and derivatives thereof, capecitabine, methotrexate, chlorambucil, busulfan, clofarabine, fludarabine, pentostatin, cyclophosphamide, etoposide, fluorouracil, gemcitabine, ifosfamide, nelarabine, mechlorethamine, procarbazine, taxol, taxotere, topotecan, vincristine and vinblastine. Additional cancer therapies that induce DNA damage in a cell are well known to a person of ordinary skill in the art and such embodiments are within the purview of the invention.

Therapeutic and sub-therapeutic amounts of certain examples of the second therapy that induce DNA damage in a cell are provided in Table 4 below:

Table 4. Therapeutic and sub-therapeutic amounts exemplary second therapies that induce DNA damage in a cell. These dosages can be adjusted for individual subjects based on medical professional's judgment. Not all indications are listed in this table and dosage regimens for indications not listed herein are well known in the art. The dosages and route of administration can also be updated based on updates in medical practices.

Drug Therapeutic dose

Adriamycin 60-75 mg/m ² as a single intravenous injection administered at 21 day intervals; or 30 mg/m ² on each of three successive days repeated every 4 weeks.

The adult dosage regimens may be suitable for paediatric cases.

An intra-arterial infusion for 1-3 days at doses of 45-100 mg/m ² . The recommended lifetime cumulative dose limit is 550 mg/m ² body surface area.

The total cumulative dose for adults aged 70 or older be restricted to 450 mg/m ² body surface area.

Cytarabine Acute Myelocytic Leukemia - induction remission: adults: 200 mg/m ² daily by continuous infusion for 5 days (120 hours) - total dose 1000 mg/m ² . This course is repeated approximately every 2 weeks.

Acute myelocytic leukemia - maintenance: adults: Maintenance programs are modifications of induction programs and, in general, use similar schedules of drug therapy as were used during induction. Most programs have a greater time spacing between courses of therapy during remission maintenance.

Acute myelocytic leukemia - induction and maintenance in children: childhood AML responds better than adult AML given similar regimens. Where the adult dosage is stated in terms of body weight or surface area, the children's dosage may be calculated on the same basis. When specified amounts of a drug are indicated for the adult dosage, these should be adjusted for children on the basis of such factors as age, body weight or body surface area.

Daunorubicin 60 to 75 mg/m2 as a single intravenous injection administered at

21 -day intervals. Idarubicin 12 mg/m2 daily for 3 days by slow (10 to 15 min) intravenous injection in combination with cytarabine. The cytarabine may be given as 100 mg/m2 daily by continuous infusion for 7 days or as cytarabine 25 mg/m2 intravenous bolus followed by cytarabine 200 mg/m2 daily for 5 days continuous infusion.

Cisplatin Metastatic Testicular Tumors: 20 mg/m ² IV daily for 5 days per cycle in combination with other approved chemotherapeutic agents. Metastatic Ovarian Tumors: 75 to 100 mg/m ² IV per cycle once every 4 weeks (DAY 1) in combination with cyclophosphamide. The dose of cyclophosphamide when used in combination with PLATINOL is 600 mg/m ² IV once every 4 weeks (DAY 1).

As a single agent, 100 mg/m ² IV per cycle once every 4 weeks. Advanced bladder cancer: 50 to 70 mg/m2 IV per cycle once every 3 to 4 weeks

Oxaliplatin Administered in combination with 5-fluorouracil/leucovorin every

2 weeks: Day 1 : 85 mg/m ² intravenous infusion in appropriate solution and leucovorin 200 mg/m ² intravenous infusion in appropriate solution over 120 minutes, followed by 5-fluorouracil 400 mg/m ² intravenous bolus over 2-4 minutes, followed by 5- fluorouracil 600 mg/m ² in appropriate solution as 22-hour continuous infusion. Day 2: leucovorin 200 mg/m ² intravenous infusion over 120 minutes, followed by 5-fluorouracil 400 mg/m ² intravenous bolus given over 2-4 minutes, followed by 5- fluorouracil 600 mg/m2 intravenous infusion in appropriate solution as a 22-hour continuous infusion.

Carboplatin Single agent: 360 mg/m ² IV on day 1 every 4 weeks.

Combination with cyclophosphamide: Carboplatin 300 mg/m ² IV on day 1 every four weeks for six cycles with cyclophosphamide 600 mg/m ² IV on day 1 every four weeks for six cycles.

Irinotecan 125 mg/m ² intravenous infusion on days 1, 8, 15, 22 with leucovorin 20 mg/m ² intravenous bolus infusion on days 1, 8, 15, 22 followed by 5-fluorouracil intravenous bolus infusion on days 1, 8, 15, 22 every 6 weeks; or

180 mg/m ² intravenous infusion on days 1, 15, 29 with leucovorin 200 mg/m ² intravenous infusion on days 1, 2, 15, 16, 29, 30 followed by 5- fluorouracil 400 mg/m ² intravenous bolus infusion on days 1, 2, 15, 16, 29, 30 and 5- fluorouracil 600 mg/m ² intravenous infusion over 22 hours on days 1, 2, 15, 16, 29, 30; or

125 mg/m2 intravenous infusion on days 1, 8, 15, 22 then 2-week rest; or

350 mg/m2 intravenous infusion over 90 minutes on day 1 every 3 weeks.

Capecitabine 2500 mg/m administered orally daily with food for 2 weeks followed by a 1-week rest period given as 3 week cycles.

Methotrexate Breast cancer: Cyclophosphamide 100 mg/m ² p.o. days 1 through

14, Methotrexate 40 mg/m ² i.v. day 1, 8, and 5 -Fluorouracil 600 mg/m ² i.v. day 1, 8. Cycle length will be 28 days ("2 weeks-on, 2 weeks-off). In patients over 60 years of age, the dosage of Methotrexate is 30 mg/m ² i.v. day 1, 8.

Gastric cancer: Methotrexate (1.5 g/m ² IV day 1, + 5 -Fluorouracil (1.5 g/m ² IV) + Leucovorin (15 mg/m ² orally or IV every 6 hours for 72 hours) + Adriamycin (30 mg/m ² IV, day 15). The schedule is repeated on day 29 for 6 cycles.

Chlorambucil 0.1 to 0.2 mg/kg body weight daily for 3 to 6 weeks as required.

Busulfan 0.8 mg per kg of ideal body weight or actual body weight, whichever is lower, administered intravenously as a two-hour infusion every six hours for four consecutive days for a total of 16 doses.

Clofarabine Ages 1-21 : 52 mg/m ² of body surface area by intravenous infusion over 2 hours daily for 5 consecutive days followed by the recovery period of 2 to 6 weeks (median 4 weeks) from the starting day of the previous cycle. The cycles are repeated following recovery or return to baseline organ function. Fludarabine 25 mg/m ² administered intravenously over a period of approximately 30 minutes daily for five consecutive days. Each 5 day course of treatment should commence every 28 days.

Pentostatin Hairy cell leukemia: Adults: IV: 4 mg/m ² every 2 weeks.

Chronic lymphocytic leukemia (off-label use): Adults: IV:

Previously treated: 4 mg/m ² once every 3 weeks in combination with cyclophosphamide and rituximab for 6 cycles; or

Previously untreated: 2 mg/m ² once every 3 weeks in combination with cyclophosphamide and rituximab for 6 cycles.

Cutaneous T-cell lymphomas, mycosis fungoides/Sezary syndrome (off-label use): Adults: IV: 4 mg/m ² once weekly for 3 weeks, then every 2 weeks for 6 weeks, then once monthly for a maximum of 6 months.

T-cell prolymphocytic leukemia, refractory (off-label use): Adults: IV: 4 mg/m2 once weekly for 4 weeks then every 2 weeks until optimum response is achieved.

Cyclophosphamide Intravenous: Initial course for patients with no hematologic deficiency: 40 mg per kg to 50 mg per kg in divided doses over 2 to 5 days; or

Oral: 1 mg per kg per day to 5 mg per kg per day for both initial and maintenance dosing.

Etoposide Testicular cancer: 50 to 100 mg/m ² per day on days 1 through 5 to

100 mg/m ² per day on days 1, 3, and 5 in combination with other approved chemotherapeutic agents.

Small cell lung cancer: 35 mg/m ² per day for 4 days to 50 mg/m ² per day for 5 days for in combination with other approved chemotherapeutic drugs.

Fluorouracil 12 mg/kg are given intravenously once daily for 4 successive days.

The daily dose should not exceed 800 mg.

Gemcitabine Ovarian Cancer: 1000 mg/m I.V. on Days 1 and 8 of each 21 -day cycle.

Breast Cancer: 1250 mg/m ² I.V. on Days 1 and 8 of each 21-day cycle.

Non-Small Cell Lung Cancer: 1000 mg/m ² I.V. on Days 1, 8, and 15 of each 28-day cycle or 1250 mg/m ² I.V. on Days 1 and 8 of each 21 -day cycle.

Pancreatic Cancer: 1000 mg/m ² I.V. once weekly for the first 7 weeks, then one week rest, then once weekly for 3 weeks of each 28-day cycle.

Ifosfamide 2000-2400 mg/m per day over a period of a minimum of 30 minutes, on 5 consecutive days.

Nelarabine Adult Dosage: 1,500 mg/m ² administered intravenously on days 1,

3, and 5 repeated every 21 days.

Pediatric Dosage: 650 mg/m ² administered intravenously over 1 hour daily for 5 consecutive days repeated every 21 days.

Mechl orethamine A total dose of 0.4 mg/kg of body weight for each course usually is given either as a single dose or in divided doses of 0.1 to 0.2 mg/kg per day.

Procarbazine Adults: Single or divided doses of 2 to 4 mg/kg/day for the first week and maintained at 4 to 6 mg/kg/day until maximum response is obtained.

Pediatric: 50 mg/m ² per day for the first week and maintained at 100 mg/m ² per day until maximum response is obtained.

Taxol Premedicated to prevent severe hypersensitivity reactions.

Previously untreated patients with carcinoma of the ovary: one of the following recommended regimens of taxol may be given every 3 weeks:

a. 175 mg/m ² I.V. followed by 75 mg/m ² cisplatin; or

b. 135 mg/m ² I.V. followed by 75 mg/m ² cisplatin.

Previously treated with chemotherapy for carcinoma of the ovary: 135 mg/m ² or 175 mg/m ² I.V. every 3 weeks.

Taxotere Breast cancer: 60 mg/m to 100 mg/m single agent;

BC adjuvant: 75 mg/m ² administered 1 hour after doxorubicin 50 mg/m ² and cyclophosphamide 500 mg/m ² every 3 weeks for 6 cycles.

NSCLC: after platinum therapy failure: 75 mg/m ² single agent.

NSCLC: chemotherapy-naive: 75 mg/m ² followed by cisplatin 75 mg/m ² .

Hormone Refractory Prostate Cancer: 75 mg/m ² with 5 mg prednisone twice a day continuously.

Gastric adenocarcinoma: 75 mg/m ² followed by cisplatin 75 mg/m ² (both on day 1 only) followed by fluorouracil 750 mg/m ² per day as a 24-hr IV. (days 1-5), starting at end of cisplatin infusion.

Squamous Cell Carcinoma of the Head and Neck Cancer: 75 mg/m ² followed by cisplatin 75 mg/m ² IV. (day 1), followed by fluorouracil 750 mg/m ² per day IV. (days 1-5), starting at end of cisplatin infusion; for 4 cycles; or 75 mg/m ² followed by cisplatin 100 mg/m ² IV. (day 1), followed by fluorouracil 1000 mg/m ² per day as a 24-hr IV. (days 1-4); for 3 cycles.

Topotecan Ovarian cancer and small cell lung cancer: 1.5 mg/m ² by IV. daily for 5 consecutive days, starting on Day 1 of a 21 -day course.

Cervical cancer: 0.75 mg/m ² by IV. on Days 1, 2, and 3 repeated every 21 days in combination with cisplatin 50 mg/m ² on Day 1. vincristine Pediatric patients: 1.5-2 mg/m ² , administered once a week.

Adults: 1.4 mg/m ² .

Vinblastine Weekly intervals at the following doses: first dose 3.7 mg/m ;

second dose 5.5 mg/m ² ; third dose 7.4 mg/m ² ; fourth dose 9.25 mg/m ² ; and fifth dose 11.1 mg/m ² .

MATERIALS AND METHODS

Colony formation assay:

Colony formation assays measures the ability of a single cell to not only survive, but also to proliferate. Thus, it is an indirect measurement of cancer stem cell activity, the ability of a single cell to give rise to a host of progeny. The BRCAl -deficient MDA-MB-436 breast cancer cells were cultured in DMEM supplemented with 10% FBS and 1% penicillin and streptomycin. BRRCA1- deficient UWB 1.289 ovarian cancer cells were cultured and maintained in 50% MEBM medium with growth factors and 50% RPMI medium supplemented with 3% FBS and 1% penicillin and streptomycin. 25 nm of mirVana miR-223 3p mimic from Ambion life technologies (Cat # 4464067) was used to deplete PARP1 protein in these cell lines. Mir223-3p was encapsulated into the lipid transfection complex, RNAiMAX. 25 nm of miR-223-3p was incubated in 500 μΙ_, Opti-MEM plus 6 μΐ of RNAiMAX for 20 mins at room temperature and then added to the cells for a final volume of 1 ml. After 48 hours, the cells were trypsinized, counted and plated in 6 well plates at a density of 4000 cells per well, in triplicates. After 14 days of incubation, colonies were stained with 0.1% crystal violet in methanol and counted using Image J software. PARPl repression by miR-223-3p was shown by western blot. PARPl antibody was purchased from Cell Signaling (46D11). Quantitative real time PCR (qRT-PCR) measuring endogenous miR-223

If miR-223-3p is a physiologic regulator of PARPl expression, then its expression should be repressed after DNA damage, when higher levels of PARPl are required to repair this damage. Mir223-3p is most highly expressed in hematopoietic cells, such as the HL60 cell line. HL60 cells were treated with 50 μΜ cytarabine (Ara-C) for lhr, 4hr, 8hr, 12hr and 24hr. Western blot analysis was performed to examine PARPl protein levels in these samples. For measuring levels of miR-223-3p, cells were collected at the above time points, RNA isolated using the Qiagen RNeasy kit. cDNA conversion was then performed using first-strand cDNA synthesis kit for miRNA from Origene (HP 100042). qRT-PCR for miR- 223 3p was performed on a 7900HT Fast Real-Time PCR system (ABI) according to Origene protocol and ACT values were calculated. Primers used were, Forward (TGTCAGTTTGTCAAATACC, SEQ ID NO: 90) and Reverse (GAACATGTCTGCGTATCTC, SEQ ID NO: 91). U6 RNA was used as an endogenous control. Alternative Non-Homologous End Joining (aNHEJ) assay:

PARPl is involved in the initial step in aNHEJ DNA double strand break repair. If PARPl is repressed, then aNHEJ is decreased. The EJ2-GFP U20S system was used to assess a HEJ. This reporter system contains single, integrated copy of reporter with I-Scel target sites. These sites were cleaved upon transfection of an I-Scel expression vector. Cells were transfected with miR-223 3p mimic using RNAiMAX. 24hours after transfection, the cells were transfected with I-Scel vector using polyethylenimine (PEI). After 72 hours, EJ2 cells were trypsinized, washed with PBS and GFP-positive cells were measured using FACSort (Becton-Dickinson, San Jose, CA). The GFP positive cells are proportional to the aNHEJ frequency.

Luciferase assay for assessing stability of PARP 1 3' UTR mRNA

A549 cells were transfected with miR-223-3p mimic using RNAiMAX as above.

After 6 hours, these cells were transfected with PARP 3'UTR plasmid fused with dual luciferase reporter from GeneCopoeia using Lipofectamine 2000. 48 hours post-transfection, cells were collected and assessed for luciferase activity using Luc-Pair Dual Luciferase assay kit from GeneCopoeia. The firefly luciferase activity is normalized against Renilla luciferase, which serves as a transfection control.

All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

Following are examples which illustrate procedures for practicing the invention.

These examples should not be construed as limiting.

EXAMPLE 1 - EFFECT OF PARP1 INHIBITION ON BAPl MUTANT HUMAN

MESOTHELIOMA CELLS BAPl (BRCA1 -Associated Protein 1) is a 90 kDa protein that binds to the RING finger domain of BRCA1. BAPl gene is located on chromosome 3p21 and it possesses tumor suppressor activity. Deletion of this region is seen in several cancers including breast cancer, lung cancer, uveal melanoma and mesothelioma. BAPl has been shown to interact with BRCAl/BARDl complex and regulate DNA damage response.

BAPl mutant cells have also been shown to be deficient in HR similar to BRCAl/2 mutant cells. These cells were treated with the PARP inhibitor, olaparib. Human Mesothelioma cells (H-Meso 01A) were cultured in RPMI media supplemented with 10% FBS and 1% Penicillin/Streptomycin. These cells were seeded in a 6-well plate at a density of 4000 cells/well and allowed to grow for 18 hours. Of the six wells, three wells were treated with 3 μΜ olaparib (LC laboratories, Cat# O-9201) each and the other three wells were considered as controls. The cells were allowed to grow for 10 days. Olaparib stayed on the cells throughout the experiment. After 10 days of incubation, colonies were stained with 0.1% crystal violet in methanol and counted using Image J software. Olaparib killed at least 80-90%) of the cells. The experiment was done three times, each in triplicates and the average from all three times was calculated (Figure 24).

EXAMPLE 2

Materials and Methods

Cell Culture, miRNA transfection and Survival Assay. The BRCA1 -deficient MDA-MB-436 breast cancer cells were cultured in DMEM supplemented with 10%> FBS and 1% penicillin and streptomycin. BRRCA1- deficient UWB 1.289 ovarian cancer cells were cultured and maintained in 50%> MEBM medium with growth factors and 50% RPMI medium supplemented with 3%> FBS and 1%> penicillin and streptomycin. BAPl-mutant H2452 mesothelioma cells were cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum and 1% penicillin and streptomycin. 25 nm of mirVana miR223-3p mimic from Ambion life technologies (Cat # 4464067) was used to deplete PARPl protein in these cell lines. Mir223-3p was encapsulated into the lipid transfection complex, RNAiMAX. 25 nm of mir223-3p was incubated in 500 UL Opti-MEM plus 6 ul of RNAiMAX for 20 mins at room temperature, and then added to the cells for a final volume of 1 ml. After 48 hours, the cells were trypsinized, counted and plated in 6 well plates at a density of 4000 cells per well, in triplicates. After 14 days of incubation, colonies were stained with 0.1%> crystal violet in methanol and counted using Image J software. PARPl repression by mir223-3p was shown by western blot. PARPl antibody was purchased from Cell Signaling (46D1 1). Results are shown in Figures 25 and 27-32. Figure 44 illustrates the depletion of other DNA repair components in addition to PARPl .

Nuclear Structure Assays and DNA Damage Foci. Nuclear structural abnormalities (micronuclei and bridging) arising from aberrant chromosomal segregation after replication fork fusion were assessed as we described. Briefly, miR223 mimic transfected cells were grown on coverslips, and then 72h after treatment, cells were fixed in 100% methanol at -20°C for 20 min. The fixed cells were mounted using DAPI-Fluoromount G clear mounting media from SouthernBiotech and analyzed within 24 hours with laser confocal scanning microscope (TCS-SP5, Leica Microsystems, Exton, PA) as we described. At least 6 distinct determinations (100-150 nuclei per determination) were performed for each group.

Confocal Immunofluorescence foci assays were performed for γ-Η2Αχ DNA damage foci analysis. After the cells were fixed like mentioned above, the coverslips were incubated with γ-Η2ΑΧ (S139) primary antibody at 1 :250 dilution in 1% BSA in TBS at 4°C overnight in a humidifying chamber. Following overnight incubation, the coverslips were washed with TBS 3 times for 5 minutes each and incubated with 1 :400 Alexa Fluor 488 for lhr at room temperature. The coverslips were washed 3 times with TBS for 5 mins each. γ-Η2ΑΧ (SI 39) primary antibody was from Millipore (Billerica, MA), and the secondary antibody conjugated with Alexa Fluor dye was from Invitrogen (Waltham, MA). After staining, coverslips were mounted with DAPI-Fluoromount G clear mounting media from Southern Biotech (Birmingham, AL) and analyzed within 24 hours with a laser confocal scanning microscope (TCS-SP5). At least 6 distinct determinations (100-150 nuclei per determination) were performed for each condition for statistical analysis. Cells with more than five foci were counted as positive. Photomicrographs of each distinct cell population were taken at equal magnifications and equal fluorescence intensities. Results of these assays are shown in Figures 33-34.

Active Replication Forks Analysis. Active Replication forks after miR223-3p mimic transfection were measured using immunofluorescent detection of BrdU foci after DNA denaturation. Briefly, 72 hours after transfection, cells were released into fresh media containing lOuM BrdU (BD Biosciences, Franklin Lakes, NJ) for 30 min. After washing, cells on coverslip were fixed and the DNA denatured using hydrochloric acid for BrdU immunostaining. The coverslips were processed for immunostaining using BrdU-specific antibody (Cell Signaling, Danvers, MA) and then incubated with a secondary antibody conjugated with Alexa Fluor dye from Invitrogen for lh. Cells were analyzed as above using the laser scanning confocal microscope. At least five hundred cells were counted for each condition from at least six distinct slides per condition for statistical analysis. Results of these assays are shown in Figures 35-36.

Replication Fork Restart. DNA fiber analysis was performed to measure replication fork restart in cells transfected with either scramble control or 25nM miR223-3p mimic. Briefly, cells were grown in 6-well tissue culture dishes. 48 hours after transfection, 20 μΜ IdU was added to growth medium, mixed and incubated for 10 min at 37°C. Media was removed and cells were washed with media containing 5nM hydroxyurea (HU). Then, cells were either treated with 5mM HIT or mock treated for 2 hours. Medium was then replaced with fresh medium containing 20 μΜ CidU and cells were incubated for 20 min at 37°C. Ceils were harvested, resuspended in PBS, 2500 cells were transferred to a positively charged microscope slide (Superfrost Plus, Daigger, Vernon Hills, XL), lysed with 6 μΐ of 0.5% SDS, 200 itiM Tris-HCl, pH 7.4, 50 rnM EDTA and incubated at room temperature for 5 min. Slides were tilted to allow DNA to spread via gravity, covered with aluminum foil. They are then air-dried for 8 min, fixed for 5 min with 3 : 1 methanokacetic acid (prepared fresh), air dried for 8 min, and stored in 70% ethanol at 4°C overnight. Slides were deproteinized in 2.5 HQ at 37°C for 1 h, blocked with 5% BSA and labeled sequentially for 1 h each with mouse anti-BrdU antibody (BD Biosciences, San Jose, CA), secondary goat anti-mouse Aiexa 568 (Invitrogen), rat anti-BrdU (Accurate Chemical, Westbury, NY) and secondary donkey anti-rat Alexa 488 (Invitrogen). Slides were mounted in PermaFluor aqueous, self- sealing mounting medium (Thermoscientific, Waltham, MA). DNA fibers were visualized using an LSM 510 confocal microscope (Zeiss, Thomwood, NY) optimized for each Alexa dye. Images were analyzed using Zeiss LSM Image Browser software. Experimental results are depicted in Figure 37.

Cytogenetic Analysis. Structural aberrations in metaphase chromosomes were scored after solid Giemsa staining as we described. Jurkat cells cultured in RPMI media with 10%) FBS and 1%> Penicillin-Streptomycin, were transfected with either scramble control or 25nM miR223-3p mimic. 48 h after transfection, the cells were replaced with fresh media containing 10 ug/mL of KaryoMAX colcemid stock (ThermoFisher Scientific, Waltham, MA) to give a final concentration of 0.1 ug/mL and incubated for 1 h in the cell culture incubator. The cells were then washed with fresh media and 2 mL of pre-warmed 75 mM KC1 was added to the cells and incubated at 37° C for 10 min in a 15mL conical tube. To the KC1, 5-10 drops of 3 : 1 methanol/acetic acid fixative was added by gently mixing the tube. The tubes were then centrifuged at 3000rpm for 5 mins and to this, fresh identical fixative was added and incubated at room temperature for 5min. The fixation step was repeated twice. The fixed cells were then added to a slide dropwise to spread them and allowed to air dry. After drying, the slides were covered with 4% Giemsa stain (Gibco) for 4min at room temperature. The stain was then washed off in water and a coverslip was mounted on each slide using Fluoromount G (SouthernBiotech) mounting media. At least 20 metaphases were counted per condition. Different chromosomal translocation events such as ring chromosome, dicentric chromosome, double minutes and cruciform structures were counted and quantitated individually. Results are shown in Figures 40-41.

Quantitative Real Time PCR (qRT-PCR) Measuring Endogenous miR223-3p. If mir223-3p is a physiologic regulator of PARPl expression, then its expression should be repressed after DNA damage, when higher levels of PARPl are required to repair this damage. Mir223-3p is most highly expressed in hematopoietic cells, such as the HL60 cell line. HL60 cells were treated with 50 uM cytarabine (Ara-C) for lhr, 4hr, 8hr, 12hr and 24hr. Western blot was performed to look at PARPl protein levels in these samples. For measuring levels of miR223-3p, cells were collected at the above time points, RNA isolated using the Qiagen RNeasy kit. cDNA conversion was then performed using first-strand cDNA synthesis kit for miRNA from Origene (HP 100042). qRT-PCR for miR223 3p was performed on a 7900HT Fast Real-Time PCR system (ABI) according to Origene protocol and ACT values were calculated. Primer used was, Forward (TGTCAGTTTGTCAAATACC) Reverse (GAACATGTCTGCGTATCTC). U6 RNA was used as an endogenous control. Results are shown in Figure 38.

Alternative Non-Homologous End Joining (aNHEJ) assay. PARPl is the initial step in aNHEJ DNA double strand break repair. If PARPl is repressed, then aNHEJ will be decreased. The EJ2-GFP U20S system was used to assess aNHEJ. This reporter system contains single, integrated copy of reporter with I-Scel target sites. These sites were cleaved upon transfection of an I-Scel expression vector. Cells were transfected with miR223 3p mimic using RNAiMAX. 24hours after transfection, the cells were transfected with I-Scel vector using polyethylenimine (PEI). After 72 hours, EJ2 cells were trypsinized, washed with PBS and GFP-positive cells were measured using FACSort (Becton-Dickinson, San Jose, CA). The GFP positive cells are proportional to the aNHEJ frequency. Results are shown in Figure 39.

Luciferase assay for assessing stability of PARPl 3' UTR mRNA. A549 cells were transfected with miR223-3p mimic using RNAiMAX as above. After 6 hours, these cells were transfected with PARP 3 'UTR plasmid fused with dual luciferase reporter from GeneCopoeia using Lipofectamine 2000. 48 hours post-transfection, cells were collected and assessed for luciferase activity using Luc-Pair Dual Luciferase assay kit from GeneCopoeia. The firefly luciferase activity is normalized against Renilla luciferase, which serves as a transfection control. Results are shown in Figures 26A-B. Statistical Analysis. Microsoft Excel or GraphPad Prism software were used for all statistical analysis. Unpaired student t-test generated the p values and a value of <0.05 was considered statistically significant.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. In addition, any elements or limitations of any invention or embodiment thereof disclosed herein can be combined with any and/or all other elements or limitations (individually or in any combination) or any other invention or embodiment thereof disclosed herein, and all such combinations are contemplated within the scope of the invention without limitation thereto.

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