A tumor-associated antigen expressed in melanoma cells with lower malignant potential.
The antigen K-1-2, detectable by a MAb is found in nevi and melanomas. It is associated with melanoma cells of low invasive and metastatic potential as shown by immunoperoxidase studies with cell lines, biopsies and autopsies: K-1-2 occurs in melanoma cell line SK-Mel 25, but not in cell line A-375. A-375 has a higher malignant potential than SK-Mel 25 because, in contrast to SK-Mel 25, it produces plasminogen activator and grows in nude mice. K-1-2 was frequently strongly expressed (greater than or equal to 50% cells positive) in flat (less than 1.5 mm) and less frequently in medium and thick primary tumors. In thick primary melanomas K-1-2 positive cells were confined to the junctional zone or to marginal, flat areas of the tumor. Only rarely does K-1-2 occur in metastases. Strong expression of the K-1-2 antigen was found less often in primary melanomas, which develop early metastases, than in tumors that had not metastasized during an observation period of 18 months. In 5 patients with disseminated metastatic disease, metastases strongly expressing K-1-2 and those negative for this marker or containing only a minor percentage of K-1-2 positive cells were observed simultaneously or at different times. These findings suggest that a change from high malignancy to low malignancy--as observed in animal systems--may also occur in human melanoma.
D000818:Animals; D000951:Antigens, Neoplasm / Q000032:analysis*; D002460:Cell Line; D006801:Humans; D007124:Immunoenzyme Techniques; D008545:Melanoma / Q000276:immunology* / Q000473:pathology / Q000556:secondary; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D009508:Nevus, Pigmented / Q000276:immunology; D012878:Skin Neoplasms / Q000276:immunology* / Q000473:pathology / Q000556:secondary
D000951:Antigens, Neoplasm