Establishment of an ascitic human melanoma cell line that metastasizes to lung and liver in nude mice.

UCLA-SO-M14, a human melanoma cell line, was cultured for ten passages in vitro. The line was converted to an ascitic form, M14-A, by transplanting M14 into CD-1 nude mice and back into tissue culture. The minimum number of M14-A cells that formed ascites in all mice (within 10-21 days) was 5 X 10(5), and over 80% of such mice developed macroscopic liver metastases. M14-A inoculated subcutaneously formed tumor at the site of injection, but rarely led to the development of metastases. However, when M14-A was inoculated subcutaneously in young mice (1-14 days old), more than 50% developed lung (but not liver) metastases. The reproducibility of the formation of ascites and metastases was confirmed by testing M14-A at various passages. M14-A may be useful as a model for the metastatic process in human melanoma.