Enhanced plasminogen activator production by highly metastatic variant cell lines of a rat mammary adenocarcinoma.

Highly metastatic cell lines have been isolated from lung foci formed by the intravenous injection of large numbers (5 X 10(6)) of cells of a poorly metastatic rat mammary adenocarcinoma (DMBA-8). The metastatic variant lines were phenotypically different and, unlike the parent line, produced high levels of plasminogen activator (PA) separable into three major bands (MW 30,000, 48,000 and 83,000) on SDS-PAGE. It is suggested that PA may play a role in the enhanced metastatic ability of these cells. Using parallel DMBA-8 clones the rate of generation of the metastatic variant cells was estimated, by fluctuation analysis, to be approximately 1.85 X 10(-6) per cell generation.