To provide a novel nucleic acid fragment that comprises an enzyme producing fragments of plasma protein that has the inhibitory action of tumor metastasis and proliferation, hydrolyzes plasma protein, for example, plasminogen, fibronectin or the like and is useful for treatment of solid carcinomas.
This is an enzyme producing a novel protein fragment that produces a plasma protein fragment having a molecular weight of about 45 kDa according to a non-reduction system SDS electrophoresis, the amino acid residue at the N- terminus of LVRIPLHKFT, acts on plasma protein in an acidic region of a pH of ≤5.0 to produce a fragment of a plasma protein having an inhibitory action of metastasis and proliferation of cancer and is an aspartic acid enzyme having a high homology to cathepsin D precursor or the like. Thus, this enzyme is useful for clinical treatment of solid cancers, for example, lung cancer, colon cancer and the like. This enzyme is obtained by maintaining human prostatic cancer cells (PC-3) in a medium including 10% fetal calf serum, substituting the culture medium with a serum-free medium, when they reach the confluent state, collecting the culture supernatant after culture, followed by centrifugation and filtration.
KAMINAKA KAZUYOSHI
TAKEMOTO SUMIYO
MAEDA HIROAKI
NOZAKI CHIKAHIDE
MIYAMOTO SEIJI
