Prolactin Fusion Proteins

The invention relates to prolactin fusion proteins which are agonists or antagonists of prolactin receptor signal transduction.

Human prolactin is a 227 amino acid polypeptide which has a molecular weight of around 24kDa and is similar in structure to growth hormone and placental lactogen. This precursor form of prolactin is proteolytically processed to a shorter form of 199 amino acids which is the active form of the hormone and is stablized by three internal disulphide bonds. Prolactin is produced by the anterior pituitary, immune cells and the breast. The secretion of prolactin from the pituitary gland is inhibited by neuro-secretory dopamine receptors of the arcuate nucleus and is stimulated by thyrotropin-releasing factor. The primary function of prolactin is the stimulation of milk production by the mammary glands. Prolactin also has a role in stimulating both cell and humoral based immunity and is capable of stimulating pancreatic islet cell proliferation.

Prolactin binds a single prolactin receptor which dimerizes with a second prolactin receptor via site one and site two binding domains to induce receptor activation. The human prolactin receptor comprises a single transmembrane domain, a ligand binding extracellular domain and a cytoplasmic domain which is required for signal transduction. Several forms of the human prolactin receptor have been characterized including a full length receptor and at least eight variants. The variants differ in the length of their extracellular and/or cytoplasmic domains. In addition to membrane localized prolactin receptor there is also a soluble form that circulates in serum and is essentially the extracellular domain. Prolactin receptors are expressed by a number of cell-types in addition to mammary tissue, for example organs of the reproductive system including the prostate, central nervous system, pituitary adrenal cortex, pancreatic islets, skin, bone, lung, heart, liver, pancreas, kidney and lymphoid tissue. The expression of prolactin receptor has also been described in breast and prostate carcinoma tissue and other tumour tissues.

Furthermore there is evidence for the involvement of prolactin in the differentiation of oligodendrocytes. For example, WO2007/106987 discloses cell culture conditions that facilitate the proliferation of neural stem cells that include the addition of prolactin to cell culture medium. Similarly WO2007/036033 describes methods to produce oligodendrocytes from neural stem cells and oligodendrocyte precursor cells that involve

the exposure of the stem/precursor cells to prolactin which enhances the formation of oligodendrocytes.

In WO2004/054516 are disclosed prolactin variants that are modified to provide prolactin variants with antagonistic activity. These variants are effective in inhibiting or suppressing prolactin receptor signal transduction and have use in the treatment of diseases such as cancer (e.g. prostate cancer, breast cancer, and leukaemia). Modified prolactin variants are also disclosed in WO2003/057729 which describes prolactin deletion mutants that are deleted for 9-14 amino terminal amino acids in combination with a mutation in the site 2 binding domain of prolactin (Glycine129Arginine) to provide an antagonist which has no residual agonist activity.

In WO2007/047803 the prophylactic effect of short term prolactin administration are described in the prevention of breast cancer in mammals susceptible to breast cancer (e.g. a HER2/neu genotype). This is surprising since there is an established association of prolactin expression with various cancers including breast cancer. Finally in WO2005/058232 is described a combination therapy that uses a growth hormone antagonist with zinc which enhances the binding of the growth hormone antagonist to prolactin receptor in cancerous conditions that over-express prolactin receptor. Growth hormone is able to bind both growth hormone receptor and prolactin receptor.

It is apparent that prolactin is involved in a large number of biological responses and pathological conditions. We disclose prolactin fusion proteins that have altered preferably enhanced pharmacokinetics and activity.

According to an aspect of the invention there is provided a nucleic acid molecule comprising a nucleic acid sequence that encodes a prolactin fusion polypeptide wherein said polypeptide comprises prolactin, or part thereof, linked directly or indirectly, to the prolactin binding domain of the prolactin receptor.

According to an aspect of the invention there is provided a fusion polypeptide comprising the amino acid sequence of prolactin, or active binding part thereof, linked directly or indirectly, to the prolactin binding domain of the prolactin receptor.

In a preferred embodiment of the invention prolactin is linked to the binding domain of the prolactin receptor by a peptide linker; preferably a flexible peptide linker.

In a preferred embodiment of the invention said peptide linking molecule comprises at least one copy of the peptide GIy GIy GIy GIy Ser.

In a preferred embodiment of the invention said peptide linking molecule comprises 2, 3, 4 or 5 copies of the peptide GIy GIy GIy GIy Ser.

In a preferred embodiment of the invention said peptide linking molecule consists of 2 copies of the peptide GIy GIy GIy GIy Ser.

In a preferred embodiment of the invention said peptide linking molecule consists of 3 copies of the peptide GIy GIy GIy GIy Ser.

In a preferred embodiment of the invention said peptide linking molecule consists of 4 copies of the peptide GIy GIy GIy GIy Ser.

In a preferred embodiment of the invention said peptide linking molecule consists of 5 copies of the peptide GIy GIy GIy GIy Ser.

In an alternative embodiment of the invention said polypeptide does not comprise a peptide linker and is a direct fusion of prolactin and the prolactin binding domain of the prolactin receptor.

In a preferred embodiment of the invention said polypeptide is an agonist.

In a preferred embodiment of the invention said prolactin polypeptide comprises or consists of an amino acid sequence wherein said amino acid sequence is represented in SEQ ID NO: 2 or 3.

In a further preferred embodiment of the invention said prolactin polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 5, 6 or 8.

According to a further aspect of the invention there is provided a nucleic acid molecule comprising a nucleic acid sequence selected from: i) a nucleic acid sequence as represented in SEQ ID NO:9; ii) a nucleic acid sequence as represented in SEQ ID NO: 12;

iii) a nucleic acid sequence as represented in SEQ ID NO: 14; iv) a nucleic acid sequence as represented in SEQ ID NO: 17; or v)a nucleic acid molecule comprising a nucleic sequence that hybridizes under stringent hybridization conditions to SEQ ID NO: 9, 12, 14 or 17 and which encodes a polypeptide that has prolactin receptor modulating activity.

Hybridization of a nucleic acid molecule occurs when two complementary nucleic acid molecules undergo an amount of hydrogen bonding to each other. The stringency of hybridization can vary according to the environmental conditions surrounding the nucleic acids, the nature of the hybridization method, and the composition and length of the nucleic acid molecules used. Calculations regarding hybridization conditions required for attaining particular degrees of stringency are discussed in Sambrook et al., Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 2001); and Tijssen, Laboratory Techniques in Biochemistry and Molecular Biology — Hybridization with Nucleic Acid Probes Part I, Chapter 2 (Elsevier, New York, 1993). The T _m is the temperature at which 50% of a given strand of a nucleic acid molecule is hybridized to its complementary strand. The following is an exemplary set of hybridization conditions and is not limiting:

Very High Stringency (allows sequences that share at least 90% identity to hybridize)

Hybridization: 5x SSC at 65°C for 16 hours

Wash twice: 2x SSC at room temperature (RT) for 15 minutes each Wash twice: 0.5x SSC at 65°C for 20 minutes each

High Stringency (allows seguences that share at least 80% identity to hybridize)

Hybridization: 5x-6x SSC at 65°C-70°C for 16-20 hours

Wash twice: 2x SSC at RT for 5-20 minutes each

Wash twice: 1 x SSC at 55°C-70°C for 30 minutes each

Low Stringency (allows seguences that share at least 50% identity to hybridize)

Hybridization: 6x SSC at RT to 55°C for 16-20 hours

Wash at least twice: 2x-3x SSC at RT to 55°C for 20-30 minutes each.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 9.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 12.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 14.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 17.

According to an aspect of the invention there is provided a polypeptide encoded by the nucleic acid according to the invention.

According to a further aspect of the invention there is provided a polypeptide comprising an amino acid sequence selected from: i) an amino acid sequence as represented in SEQ ID NO: 10; ii) an amino acid sequence as represented in SEQ ID NO: 11 ; iii) an amino acid sequence as represented in SEQ ID NO: 13; iv) an amino acid sequence as represented in SEQ ID NO:15; v) an amino acid sequence as represented in SEQ ID NO:16; or vi) an amino acid sequence as represented in SEQ ID NO:18, wherein said polypeptide has prolactin receptor modulating activity.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 10 and which is a prolactin receptor agonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 11 and which is a prolactin receptor agonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 13 and which is a prolactin receptor agonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 15 and which is a prolactin receptor agonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 16 and which is a prolactin receptor agonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 18 and which is a prolactin receptor agonist.

According to an aspect of the invention there is provided a homodimer consisting of two polypeptides wherein each of said polypeptides comprises: i) a first part comprising prolactin or a modified prolactin, or a receptor binding domain thereof, optionally linked by a peptide linking molecule to ii) a second part comprising a prolactin binding domain of the prolactin receptor.

In a preferred embodiment of the invention said homodimer comprises two polypeptides comprising or consisting of SEQ ID NO: 10, 11 , 13, 15, 16 or 18 and which is a prolactin receptor agonist.

In an alternative preferred embodiment of the invention prolactin is a modified prolactin antagonist polypeptide.

In a preferred embodiment of the invention said modified prolactin polypeptide comprises an amino acid sequence wherein said amino acid sequence is modified at position 129 of human prolactin as represented in SEQ ID NO: 2 or 3.

In a preferred embodiment of the invention said modification is an amino acid substitution. Preferably said substitution replaces a glycine amino acid residue with an arginine amino acid residue.

Preferably said modification further comprises the deletion of at least 9, 10, 11, 12, 13 or 14 amino terminal amino acid residues of the amino acid sequence as represented in SEQ ID NO: 2 or 3

In a further preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 5, 6 or 8.

According to a further aspect of the invention there is provided a nucleic acid molecule comprising a nucleic acid sequence selected from: i) a nucleic acid sequence as represented in SEQ ID NO:19; ii) a nucleic acid sequence as represented in SEQ ID NO:22; iii) a nucleic acid sequence as represented in SEQ ID NO: 24; iv) a nucleic acid sequence as represented in SEQ ID NO: 27; v) a nucleic acid sequence as represented in SEQ ID NO: 29; vi) a nucleic acid sequence as represented in SEQ ID NO: 32; vii) a nucleic acid sequence as represented in SEQ ID NO: 34; or viii) a nucleic acid molecule comprising a nucleic sequence that hybridizes under stringent hybridization conditions to SEQ ID NO: 19, 22, 24, 27, 29, 32 or 34 and which encodes a polypeptide that has prolactin receptor antagonist.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 19.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 22.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 24.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 27.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 29.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 32.

In a preferred embodiment of the invention said nucleic acid molecule comprises or consists of a nucleic acid sequence as represented in SEQ ID NO: 34.

According to an aspect of the invention there is provided a polypeptide encoded by the nucleic acid according to the invention.

According to a further aspect of the invention there is provided a polypeptide comprising an amino acid sequence selected from: i) an amino acid sequence as represented in SEQ ID NO: 10; ii) an amino acid sequence as represented in SEQ ID NO: 11 ; iii) an amino acid sequence as represented in SEQ ID NO: 13; iv) an amino acid sequence as represented in SEQ ID NO: 15; v) an amino acid sequence as represented in SEQ ID NO: 16; vi) an amino acid sequence as represented in SEQ ID NO: 18; vii) an amino acid sequence as represented in SEQ ID NO:20 viii) an amino acid sequence as represented in SEQ ID NO:21 ix) an amino acid sequence as represented in SEQ ID NO:23; x) an amino acid sequence as represented in SEQ ID NO:25; xi) an amino acid sequence as represented in SEQ ID NO:26; or xii) an amino acid sequence as represented in SEQ ID NO:28; wherein said polypeptide is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 10 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 11 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 13 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 15 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 16 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 18 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 20 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 21 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 23 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 25 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 26 and which is a prolactin receptor antagonist.

In a preferred embodiment of the invention said polypeptide comprises or consists of an amino acid sequence as represented in SEQ ID NO: 28 and which is a prolactin receptor antagonist.

According to an aspect of the invention there is provided a homodimer consisting of two polypeptides wherein each of said polypeptides comprises: i) a first part comprising a modified prolactin, or a receptor binding domain thereof, optionally linked by a peptide linking molecule to ii) a second part comprising a prolactin binding domain of the prolactin receptor.

In a preferred embodiment of the invention said homodimer comprises two polypeptides comprising or consisting of an amino acid sequence selected from: SEQ ID NO: 10, 11, 13, 15, 16, 18, 20, 21 , 23, 25, 26, or 28 and which is a prolactin receptor antagonist.

According to a further aspect of the invention there is provided a vector comprising a nucleic acid molecule according to the invention.

In a preferred embodiment of the invention said vector is an expression vector adapted to express the nucleic acid molecule according to the invention.

A vector including nucleic acid (s) according to the invention need not include a promoter or other regulatory sequence, particularly if the vector is to be used to introduce the nucleic acid into cells for recombination into the genome for stable transfection. Preferably the nucleic acid in the vector is operably linked to an appropriate promoter or other regulatory elements for transcription in a host cell. The vector may be a bi- functional expression vector which functions in multiple hosts. By "promoter" is meant a nucleotide sequence upstream from the transcriptional initiation site and which contains all the regulatory regions required for transcription. Suitable promoters include constitutive, tissue-specific, inducible, developmental or other promoters for expression in eukaryotic or prokaryotic cells. "Operably linked" means joined as part of the same nucleic acid molecule, suitably positioned and oriented for transcription to be initiated from the promoter. DNA operably linked to a promoter is "under transcriptional initiation regulation" of the promoter.

In a preferred embodiment the promoter is a constitutive, an inducible or regulatable promoter.

According to a further aspect of the invention there is provided a cell transfected or transformed with a nucleic acid molecule or vector according to the invention.

Preferably said cell is a eukaryotic cell. Alternatively said cell is a prokaryotic cell.

In a preferred embodiment of the invention said cell is selected from the group consisting of; a fungal cell (e.g. Pichia spp, Saccharomyces spp, Neurospora spp); insect cell (e.g. Spodoptera spp); a mammalian cell (e.g. COS cell, CHO cell); a plant cell.

In a preferred embodiment of the invention said cell is stably transfected. In an alternative preferred embodiment of the invention said cell is transiently transfected.

According to a further aspect of the invention there is provided a pharmaceutical composition comprising a polypeptide according to the invention including an excipient or carrier.

In a preferred embodiment of the invention said pharmaceutical composition is combined with a further therapeutic agent.

When administered the pharmaceutical composition of the present invention is administered in pharmaceutically acceptable preparations. Such preparations may routinely contain pharmaceutically acceptable concentrations of salt, buffering agents, preservatives, compatible carriers, and optionally other therapeutic agents for example chemotherapeutic agents.

The pharmaceutical compositions of the invention can be administered by any conventional route, including injection. The administration and application may, for example, be oral, intravenous, intraperitoneal, intramuscular, intracavity, intra-articuar, subcutaneous, topical (eyes), dermal (e.g a cream lipid soluble insert into skin or mucus membrane), transdermal, or intranasal.

Pharmaceutical compositions of the invention are administered in effective amounts. An

"effective amount" is that amount of pharmaceuticals/compositions that alone, or together with further doses or synergistic drugs, produces the desired response. This may involve only slowing the progression of the disease temporarily, although more

preferably, it involves halting the progression of the disease permanently. This can be monitored by routine methods or can be monitored according to diagnostic methods.

The doses of the pharmaceuticals compositions administered to. a subject can be chosen in accordance with different parameters, in particular in accordance with the mode of administration used and the state of the subject (i.e. age, sex). When administered, the pharmaceutical compositions of the invention are applied in pharmaceutically-acceptable amounts and in pharmaceutically-acceptable compositions. When used in medicine salts should be pharmaceutically acceptable, but non- pharmaceutically acceptable salts may conveniently be used to prepare pharmaceutically-acceptable salts thereof and are not excluded from the scope of the invention. Such pharmacologically and pharmaceutically-acceptable salts include, but are not limited to, those prepared from the following acids: hydrochloric, hydrobromic, sulfuric, nitric, phosphoric, maleic, acetic, salicylic, citric, formic, malonic, succinic, and the like. Also, pharmaceutically-acceptable salts can be prepared as alkaline metal or alkaline earth salts, such as sodium, potassium or calcium salts.

The pharmaceutical compositions may be combined, if desired, with a pharmaceutically- acceptable carrier. The term "pharmaceutically-acceptable carrier" as used herein means one or more compatible solid or liquid fillers, diluents or encapsulating substances that are suitable for administration into a human. The term "carrier" denotes an organic or inorganic ingredient, natural or synthetic, with which the active ingredient is combined to facilitate the application. The components of the pharmaceutical compositions also are capable of being co-mingled with the molecules of the present invention, and with each other, in a manner such that there is no interaction that would substantially impair the desired pharmaceutical efficacy.

The pharmaceutical compositions may contain suitable buffering agents, including: acetic acid in a salt; citric acid in a salt; boric acid in a salt; and phosphoric acid in a salt.

The pharmaceutical compositions also may contain, optionally, suitable preservatives, such as: benzalkonium chloride; chlorobutanol; parabens and thimerosal.

The pharmaceutical compositions may conveniently be presented in unit dosage form and may be prepared by any of the methods well-known in the art of pharmacy. All methods include the step of bringing the active agent into association with a carrier that

constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing the active compound into association with a liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the product.

Compositions suitable for oral administration may be presented as discrete units, such as capsules, tablets, lozenges, each containing a predetermined amount of the active compound. Other compositions include suspensions in aqueous liquids or non-aqueous liquids such as syrup, elixir or an emulsion.

Compositions suitable for parenteral administration conveniently comprise a sterile aqueous or non-aqueous preparation that is preferably isotonic with the blood of the recipient. This preparation may be formulated according to known methods using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation also may be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example, as a solution in 1 , 3-butane diol. Among the acceptable solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono-or di-glycerides. In addition, fatty acids such as oleic acid may be used in the preparation of injectables. Carrier formulation suitable for oral, subcutaneous, intravenous, intramuscular, etc. administrations can be found in Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, PA.

According to a further aspect of the invention there is provided a method to treat a human subject suffering from a condition that would benefit from administration of a prolactin agonist comprising administering an effective amount of at least one polypeptide according to the invention.

In a preferred method of the invention said polypeptide is administered intravenously.

In an alternative preferred method of the invention said polypeptide is administered subcutaneously.

In a further preferred method of the invention said polypeptide is administered at two day intervals; preferably said polypeptide is administered at weekly, 2 weekly or monthly intervals.

In a preferred method of the invention said condition is associated with over-expression of prolactin receptor.

In a preferred method of the invention said condition is cancer.

As used herein, the term "cancer" refers to cells having the capacity for autonomous growth, i.e., an abnormal state or condition characterized by rapidly proliferating cell growth. The term is meant to include all types of cancerous growths or oncogenic processes, metastatic tissues or malignantly transformed cells, tissues, or organs, irrespective of histopathologic type or stage of invasiveness. The term "cancer" includes malignancies of the various organ systems, such as those affecting, for example, lung, breast, thyroid, lymphoid, gastrointestinal, and genito-urinary tract, as well as adenocarcinomas which include malignancies such as most colon cancers, renal-cell carcinoma, prostate cancer and/or testicular tumours, non-small cell carcinoma of the lung, cancer of the small intestine and cancer of the esophagus. The term "carcinoma" is art recognized and refers to malignancies of epithelial or endocrine tissues including respiratory system carcinomas, gastrointestinal system carcinomas, genitourinary system carcinomas, testicular carcinomas, breast carcinomas, prostatic carcinomas, endocrine system carcinomas, and melanomas. Exemplary carcinomas include those forming from tissue of the cervix, lung, prostate, breast, head and neck, colon and ovary. The term "carcinoma" also includes carcinosarcomas, e.g., which include malignant tumours composed of carcinomatous and sarcomatous tissues. An "adenocarcinoma" refers to a carcinoma derived from glandular tissue or in which the tumor cells form recognizable glandular structures. The term "sarcoma" is art recognized and refers to malignant tumors of mesenchymal derivation. The invention includes all cancers that over-express prolactin receptor or prolactin; for example conditions that result in hyperprolactamia.

In a preferred method of the invention said cancerous condition is breast cancer or prostate cancer.

In a preferred method of the invention said breast cancer condition is selected from the group consisting of: mammary carcinoma, lobular carcinoma, intraductal carcinoma, medullary breast carcinoma, mucinous breast cancer, papillary breast cancer, inflammatory breast cancer.

According to a further aspect of the invention there is provided a method to modulate the proliferation or differentiation of a neural stem cell comprising: i) providing a preparation comprising a culture of neural stem cells, at least one polypeptide according to the invention and cell culture media components sufficient to support the growth of said neural stem cells; and ii) providing cell culture conditions that maintain said neural stem cells or differentiate said neural stem cells into at least one neural cell-type.

In a preferred method of the invention said neural stem cells are progenitors of oligodendrocytes.

In a preferred method of the invention said method modulates the differentiation of said neural stem cell or progenitor cell into at least one neural cell-type. The method may be an in vivo method or an in vitro method.

The term "stem cell" represents a generic group of undifferentiated cells that possess the capacity for self-renewal while retaining varying potentials to form differentiated cells and tissues. Stem cells can be pluripotent or multipotent. A pluripotent stem cell is a cell that has the ability to form all tissues found in an intact organism although the pluripotent stem cell cannot form an intact organism. A multipotent cell has a restricted ability to form differentiated cells and tissues. Typically adult stem cells are multipotent stem cells and are the precursor stem cells or lineage restricted stem cells that have the ability to form some cells or tissues and replenish senescing or damaged cells/tissues. An example of a multipotent stem cell is a neural stem cell. Methods for the isolation and maintenance of neural stem cells are known in the art. For example, US2007/0020608 describes a method for the generation of neural progenitor cells from pluripotent blastocyst derived stem cells. In WO2006/100088 a method for the derivation of neural stem cells from dental progenitor cells is disclosed that involves the culturing of dental progenitor cells as spheres that are disaggregated into single cells that re-aggregate into spheres which differentiate into neural stem cells. Moreover, US2006240553 and US2006263876 each describe the isolation neural stem cells from different sources; the central nervous system and neural crest respectively.

According to a further aspect of the invention there is provided a polypeptide according to the invention for use in the differentiation of neural stem cells or neural progenitor cells into at least one differentiation neural cell-type.

According to a further aspect of the invention there is provided a polypeptide according to the invention for use in the stimulation of a pancreatic islet cell.

In a preferred embodiment of the invention said pancreatic islet cell is a α, β or δ islet cell.

According to a further aspect of the invention there is provided a polypeptide according to the invention for use as an adjuvant of the immune system.

According to a further aspect of the invention there is provided a monoclonal antibody, or active binding part thereof, that binds the polypeptide or dimer according to the invention.

Preferably said monoclonal antibody is an antibody that binds the polypeptide or dimer but does not specifically bind prolactin, modified prolactin or prolactin receptor individually.

The monoclonal antibody binds a conformational antigen presented either by the polypeptide of the invention or a dimer comprising the polypeptide of the invention.

In a further aspect of the invention there is provided a method for preparing a hybridoma cell-line producing monoclonal antibodies according to the invention comprising the steps of: i) immunising an immunocompetent mammal with an immunogen comprising at least one polypeptide according to the invention; ii) fusing lymphocytes of the immunised immunocompetent mammal with myeloma cells to form hybridoma cells; iii) screening monoclonal antibodies produced by the hybridoma cells of step

(ii) for binding activity to the polypeptide of (i); iv) culturing the hybridoma cells to proliferate and/or to secrete said monoclonal antibody; and v) recovering the monoclonal antibody from the culture supernatant.

Preferably, the said immunocompetent mammal is a mouse. Alternatively, said immunocompetent mammal is a rat.

The production of monoclonal antibodies using hybridoma cells is well-known in the art. The methods used to produce monoclonal antibodies are disclosed by Kohler and Milstein in Nature 256, 495-497 (1975) and also by Donillard and Hoffman, "Basic Facts about Hybridomas" in Compendium of Immunology V.ll ed. by Schwartz, 1981, which are incorporated by reference.

According to a further aspect of the invention there is provided a hybridoma cell-line obtained or obtainable by the method according to the invention.

According to a further aspect of the invention there is provided a diagnostic test to detect a polypeptide according to the invention in a biological sample comprising:

i) providing an isolated sample to be tested; ii) contacting said sample with a ligand that binds the polypeptide according to the invention; and iii) detecting the binding of said ligand in said sample.

In a preferred embodiment of the invention said ligand is an antibody; preferably a monoclonal antibody.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be

understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

An embodiment of the invention will now be described by example only and with reference to the following figures:

Figure 1a is the nucleic acid sequence of human prolactin (bold indicates the nucleic acid encoding the signal sequence); Figure 1b is the amino acid sequence of human prolactin (bold represents the signal sequence);

Figure 2a is the nucleic acid sequence of human prolactin receptor (bold indicates the nucleic acid encoding the signal sequence); Figure 2b is the amino acid sequence of human prolactin receptor (bold indicates the signal sequence);

Figure 3a is the nucleic acid sequence of the extracellular domain of the human prolactin receptor; Figure 3b is the amino acid sequence of the extracellular domain of the human prolactin receptor;

Figure 4a is the nucleic acid sequence of prolactin chimera 8B7v2: PRL linked via a G4Sx6 linker to PRLRext. Nucleotide sequence: 1317bp (not including signal sequence). Signal sequence is shown in bold. Linker region underlined; Figure 4b is the amino acid sequence of 8B7v2: PRL linked via a G4Sx6 linker to PRLRext amino acid Protein sequence: 439 amino acids (not including signal sequence);

Figure 5a is the nucleic acid sequence of 8B7v2-Hist: PRL linked via a G4Sx6 linker to PRLRext. Nucleotide and protein sequence represents the full sequence expressed in E. coli with a 6X Histidine tag and no signal sequence. Bold letters refer to Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics; Figure 5b is the amino acid sequence (447 amino acids not including Met);

Figure 6a is the nucleic acid sequence of 8B7v3: PRL linked directly to PRLRext DNA Nucleotide sequence: 1227bp (not including signal sequence). Signal sequence shown in bold; Figure 6b 8B7v3: PRL linked directly to PRLRext amino acid (409 amino acids not including signal sequence);

Figure 7a is the nucleic acid sequence of 8B7v3-Hist: PRL linked directly to PRLRext DNA Nucleotide and protein sequence represents the full sequence expressed in E. coli with a 6X Histidine tag and no signal sequence. Bold letters refer to Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics; Figure 7b is the amino acid sequence (417 amino acids not including Met); and

Figure 8 shows western blot of CHO cell expressed 8B7v2. Samples were prepared as described in the presence of DTT. Lane 1 : Ladder, lane 2: 8B7v2 (1Ox concentrated media from stable cell line), Lane 3: -ve control (1Ox concentrated media from 1B7stop stable cell line), Lane 4: Positive control, 250ng rh-PRL. 8b7v2 separates at approximately 75kDa: Non glycosylated MW = 51.4kDa. PRL control protein has a MW of ~22kDa.

Figure 9a is the nucleic acid sequence of 8B8v2: PRL (G129Rmutation) linked via G4Sx6 linker to PRLRext, signal sequence shown in bold. G129R mutation highlighted; Figure 9b is the amino acid sequence of 8B8v2 (439 amino acids not including signal sequence). Signal sequence shown in bold. G129R mutation highlighted.

Figure 10a is the nucleic acid sequence of 8B8v2-Hist: PRL (G129Rmutation) linked via G4Sx6 linker to PRLRext. G129R mutation highlighted Nucleotide and protein sequence represents the full sequence expressed in E. coli with a 6X Histidine tag and no signal sequence. Bold letters refer to Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics. G129R mutation highlighted; Figure 10b amino acid sequence of 8B8v2-Hist: PRL : 447 amino acids (not including Met). G129R mutation highlighted.

Figure 11a is the nucleic acid sequence of 8B8v3: PRL (G129R mutation) linked directly to PRLRext. (nucleotide sequence: 1227bp not including signal sequence). Signal sequence shown in bold. G129R mutation highlighted; Figure 11b amino acid sequence of 8B8v3 409 amino acids (not including signal sequence). Signal sequence shown in bold. G129R mutation highlighted

Figure 12a is the nucleic acid sequence of 8B8v3-Hist: PRL (G129R mutation) linked directly to PRLRext. Nucleotide and protein sequence represents the full sequence expressed in E. coli with a 6X Histidine tag and no signal sequence. Bold letters refer to

Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics.

G129R mutation highlighted; Figure 12b amino acid sequence of 8B8v3-Hist: PRL: 417 amino acids (not including Met). G129R mutation highlighted

Figure 13a is the nucleic acid sequence of 8B9v2: Consists of PRL (Deleted N-terminal residues 1-9/C11S/G129R mutations) linked via a G4S x6 linker to PRLRext. Nucleotide sequence; 1290bp (not including signal sequence). Signal sequence is shown in bold.

C11S and G129R mutations highlighted; Figure 13b amino acid sequence of 8B9v2:

430 amino acids (not including signal sequence). Signal sequence shown in bold.

C11S/G129R mutations highlighted.

Figure 14a is the nucleic acid sequence of 8B9v2-Hist: Consists of PRL (Deleted N- terminal residues 1-9/C11S/G129R mutations) linked via a G4S x6 linker to PRLRext.

Nucleotide and protein sequence represents the full sequence expressed in E. coli with a

6X Histidine tag and no signal sequence. Bold letters refer to Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics. C11S and G129R mutations highlighted; Figure 14b amino acid sequence of 8B9v2-Hist:: 438 amino acids

(not including Met). C11S/G129R mutations highlighted;

Figure 15a is the nucleic acid sequence of 8B9v3: Consists of PRL (Deleted N-terminal residues 1-9/C11S/G129R mutations) linked directly to PRLRext. Nucleotide sequence: 1200bp (not including signal sequence). Signal sequence shown in bold. C11S/G129R mutations highlighted; Figure 15b amino acid sequence of 8B9v3: 400 amino acids (not including signal sequence). Signal sequence shown in bold. C11S/G129R mutations highlighted and

Figure 16a is the nucleic acid sequence of 8B9v3-Hist: Consists of PRL (Deleted N- terminal residues 1-9/C11S/G129R mutations) linked directly to PRLRext. Nucleotide and protein sequence represents the full sequence expressed in E. coli with a 6X Histidine tag and no signal sequence. Bold letters refer to Xho1 and 6x Hist residues. * refers to stop codon. ATG start codon shown in bold italics. C11S and G129R mutations highlighted; Figure 16b is the amino acid sequence of 8B9v3-Hist: 408 amino acids (not including Met). C11S/G129R mutations highlighted.

Materials and Methods

Testing of prolactin fusion proteins

Assays that test the activity of prolactin are known in the art. For example the Nb2 cell proliferation assay is a bioassay for lactogenic hormones that stimulates the the proliferation of Nb2 lymphoma cells in vitro; see Tanaka et al (1980) J Clin Endocrinol Metab 51: p1058-1063; Gout et al (1980) Cancer Res 40: 2433-2436; Bernichtein et al (2001) 142(9): 3950-3963.

Immunological testing

Immunoassays that measure the binding of prolactin or prolactin receptor to polyclonal and monoclonal antibodies are known in the art. Commercially available antibodies are available to detect prolactin or prolactin receptor in samples and also for use in competitive inhibition studies. For example, see http://www.abcam.com/index.html. Abeam PLC.

Recombinant Production of fusion proteins

The components of the fusion proteins were generated by PCR using primers designed to anneal to the ligand or receptor and to introduce suitable restriction sites for cloning into the target vector. The template for the PCR comprised the target gene and was obtained from IMAGE clones, cDNA libraries or from custom synthesised genes. Once the ligand and receptor genes with the appropriate flanking restriction sites had been synthesised, these were then ligated either side of the linker region in the target vector. The construct was then modified to contain the correct linker without flanking restriction sites by the insertion of a custom synthesised length of DNA between two unique restriction sites either side of the linker region, by mutation of the linker region by ssDNA modification techniques, by insertion of a primer duplex/multiplex between suitable restriction sites or by PCR modification.

Alternatively, the linker with flanking sequence, designed to anneal to the ligand or receptor domains of choice, was initially synthesised by creating an oligonucleotide duplex and this processed to generate double-stranded DNA. PCRs were then performed using the linker sequence as a "megaprimer", primers designed against the

opposite ends of the ligand and receptor to which the "megaprimer" anneals to and with the ligand and receptor as the templates. The terminal primers were designed with suitable restriction sites for ligation into the expression vector of choice.

Expression and Purification of Prolactin Fusion Proteins

Expression was carried out in a suitable system (e.g. mammalian CHO cells, E. coli, etc.) and this was dependant on the vector into which the LR-fusion gene was generated. Expression was then analysed using a variety of methods which could include one or more of SDS-PAGE, Native PAGE, western blotting, ELISA.

Purification was carried out using a suitable combination of one or more chromatographic procedures such as ion exchange chromatography, hydrophobic interaction chromatography, ammonium sulphate precipitation, gel filtration, size exclusion and/or affinity chromatography (using nickel/cobalt-resin, antibody-immobilised resin and/or ligand/receptor-immobilised resin).

Purified protein was analysed using a variety of methods which could include one or more of Bradford's assay, SDS-PAGE, Native PAGE, western blotting, ELISA.

Characterisation of Prolactin fusions

Denaturing PAGE, native PAGE gels and western blotting were used to analyse the fusion polypeptides and western blotting performed with antibodies non-conformationally sensitive to the LR-fusion. Native solution state molecular weight information can be obtained from techniques such as size exclusion chromatography using a Superose G200 analytical column and analytical ultracentrifugation.

Construction of Chimeric clones

All clones were ligated using the restriction enzymes Nhe1/ Hindlll, into the mammalian expression plasmid pSecTag-link. Clones were attached to the secretion signal for human prolactin for efficient secretion into cell media. The whole gene for 8b7v2 was cloned using gene synthesis and cloned into the mammalian expression vector pSecTag-link to form pPRLsecTag-8b7v2

Mammalian stable expression

A mammalian expression system has been established using a modification of the invitrogen vector pSecTag-V5/F RT- Hist

Invitroqen's FIp-In system

This system allows for the rapid generation of stable clones into specific sites within the host genome for high expression. This can be used with either secreted or cytoplasmic expressed proteins. FIp-In host cell lines (flp-ln CHO) have a single FIp recombinase target (FRT) site located at a transcriptionally active genomic locus Stable cell lines are generated by co-transfection of vector (Containing FRT target site) and pOG44 (a [plasmid that transiently expresses flp recombinase) into FIp-In cell line. Selection is with Hygromycin B. There is no need for clonal selection since integration of DNA is directed. Culturing FIp-In Cell lines: followed manufactures instruction using basic cell culture techniques.

Stable transfection of CHO FIp-In cells using Fugene-6

The day before transfection CHO FIp-In cells were seeded at 6 x 10E5 per 100mm petri dish in a total volume of 10ml of Hams F12 media containing 10% (v/v) Fetal Calf Serum, 1% Penicillin/streptomycin and 4mM L-glutamine. The next day added 570 μl of serum free media (containing no antibiotics) to a 1.5ml polypropylene tube. 30μl of fugene-6 was then added and mixed by gentle rolling. A separate mix of plasmids was set up for each transfection which combined 2μg plasmid of interest with 18μg pOG44 (plasmid contains recombinase enzyme necessary for correct integration of plasmid into host genome). Control plate received no plasmid. This was mixed with fugene-6 by gentle rolling, left @ RmT for 15 minutes, then applied drop-wise to the surface of the each petri dish containing CHO FIp-In cells in F12 media + 10% FCS. The plates were gently rolled to ensure good mixing and left for 24 hrs @ 37°C/5% CO2. The next day media was exchanged for selective media containing hygromycin B @ 600ug/ml. Cells were routinely kept at 60% confluency or less. Cells were left to grow in the presence of 600ug/ml hygromycin B until control plate cells (non transfected cells) had died (i.e. no hygromycin resistance).

SDS-PAGE Analysis

Testing expression from Stable CHO cell lines

Confluent CHO FIp-In cell lines expressing the protein of interest were grown in 75cm2 flasks for approximately 3-4 days in serum free media, at which point samples were taken and concentrated using acetone precipitation. Samples were mixed with an equal volume of laemmli loading buffer in the presence or absence of 25mM DTT and boiled for 5 minutes. Samples were analysed by SDS-PAGE and transferred to a PVDF membrane. After blocking in 5% (w/v) Milk protein in PBS-0.05% (v/v) Tween 20, sample detection was carried out using a specific anti-IGF-1 antibody together with a

Horse Radish Peroxidase (HRP) conjugated secondary antibody. Visualisation was by chemiluminesence on photographic film using an HRP detection kit.

Testing expression from transient tansfections

CHO FIp-In cells were seeded at 0.25x10E6 cells per well of a 6 well plate in a total volume of 2ml media (DMEM, F12, 10% FCS + P/S + L-glutamine + Zeocin). Cells were left to grow o/n. Cells were then transfected using either TranslT-CHO Reagent (Mirus) or fugene-6 at the specified reagent ratios stated in table 1. Control transfections were set up using 1B7stop (GH containing chimeric molecule). Briefly, if using TranslT reagent, 20OuI of Serum free media (OPTI MEM) was added to a 1.5ml eppendorff per transfection followed by 2ug DNA. The tubes were left for 15 minutes at RmT. 1ul of CHO Mojo Reagent was then added, mixed and left for a further 15 minutes. Media was changed to serum free and the transfection mix pippetted dropwise onto the surface of the appropriate well Briefly, if using Fugene-6 reagent, 94ul of Serum free media (OPTI MEM) was added to a 1.5ml eppendorff per transfection followed by 2ug DNA. The tubes were left for 15 minutes at RmT. Trasfection mix was then pippetted drop wise onto the surface of the appropriate well containing serum free media. All plate were left @ 37°C/5% CO2 for 2-3days. If required samples were concentrated using acetone precipitation.

Cell line for testing Prolactin Chimera Activity

Nb2 ceils (Rat lymphoma cell line)#

Growth Media

FM: Fischer's medium containing 50U/ml penicillin, 50ug/ml streptomycin 10FBS: 10% Foetal bovine serum

10HS: 10% Horse serum (lactogen deficient)

2-ME: 5OuM 2-mercaptoethanol (add this to other components only when needed)

HEPES = HEPES buffer used at 15mM (add 7.5ml to 500ml media)

Assay Media (NO FBS) FM: Fischer's medium containing 50U/ml penicillin, 50ug/ml streptomycin

10HS:10% Horse serum (lactogen deficient)

2-ME: 5OuM 2-mercaptoethanol (add this to other components only when needed)

HEPES = HEPES buffer used at 15mM (add 7.5ml to 500ml media)

Reagents PBS (Oxiod: BR0014G, 1 tablet dissolved iniOOml MiIIiQ water)

Microplate reader capable of reading at 490nm

MTS reagent; Promega: Cat# G358C, Lot# 24464403 [Ready to use One Solution

Reagent: add 2OuI directly to media]

PRL: Obtained from abeam (purified protein) Concentrated media from ARCBioserv: PRL chimera 87bv2 (x10 concentrated: Date

Received 9 ^th September 08)

Control concentrated media from ARCBioserv (x7 concentrated: Date received: 28 ^th July

08)

96 well plate Promega CellTitre 96 AQueous Non-Radioactive Proliferation Assay Reagents (Cat#

G358C, Lot# 24464403, Ready to use One Solution Reagent: add 2OuI directly to media)

Basic Bioassay for Prolactin Activity

1. Take Nb2 cells and wash twice with ~ 20ml of Assay media. Resuspend at 5.5x10E5 cells per ml in Assay media.

2. Grow cells o/n in T75 flasks to deplete the cells of lactogen @ 37C, 5% CO2.

3. For the assay: Count cells and adjust density to ~ 2 x 10E4 cells in 5OuI (4 x 10E5 cells per ml) in Assay media. Plate on a 96 well plate.

4. Prepare a series of PRL standards as show in table below. Prepare sample and control dilutions as shown. Add 5OuI of each to allocated wells. 5. Grow cells in the presence of PRL and test samples for 3 days @ 37C/5%CO2.

6. To Assay: Add 2OuI of CellTitre reagent and leave at 37C for 2-6hrs

7. Record the A490nm reading of each well using a microplate reader.

Controls; 1. Assay medium plus substrate (no bioactive factor): determines the amount of non-enzymic hydrolysis of substrate. These values are subtracted from each of the experimental values. 2. Cells only plus substrate (no bioactive factor): this represents how much the cells have grown in the absence of factor.

Prolactin-Dependent Nb2 Lymphoma Cell Line [Rat Cells]

1. Pre-T cell origin whose proliferation depends on prolactin acting as a growth factor.

2. The mitogenic response of the cells is highly specific for mammalian lactogens and is mediated by specific cell surface receptors.

3. Cells have a modified prolactin receptor, which can be mitogenically stimulated by IL2.

In vitro Proliferation Assay Using Nb2-11 Cell line

The ability of the Cell line Nb2 to proliferate in the presence of lactogen and assaying of endogenous dehydrogenase activity using the Celltitre Assay reagent (Promega). Media from CHO FIp-In cell line stably expressing 8b7v2 (serum free adapted and in suspension) was tested against control media (CHO FIp-In cells only) for lactogenic activity using the rat lymphoma cell line, Nb2-11.

Results show, see Figure 17, that 8b7v2 media contains active Prolactin Chimera. Control media shows a low level of interference. Approximate concentration of 8b7v2 from data = 900ng/ml.