Plasminogen activator secretion by established lines of human ovarian carcinoma cells in vitro

Ten human ovarian carcinoma cell lines (A121, A121[as], Caov-3, Caov-4, NIH:OVCAR-3, OVCA 420, OVCA 429, OVCA 432, OVCA 433, and SK-OV-3) were examined for secretion of plasminogen activators (PAs) using a chromogenic PA assay and SDS-PAGE zymography. PA activity was detected in conditioned media from all 10 cell lines. PA levels secreted by the 10 individual lines in a 24-hr period spanned a large range, with the extremes being 8 and 5244 milliPloug units (mPU)/10 6 cells for SK-OV-3 and OVCA 420 cells, respectively. Secreted PAs were identified as urokinase (UK)-like or tissue plasminogen activator (tPA)-like using dual criteria of comigration with UK or tPA standards on SDS-PAGE zymography and fibrin-dependence characteristics. Using both criteria, all 10 cell types produced UK-like activity, while tPA-like activity was produced by only 5 of the lines: A121[as], Caov-3, NIH:OVCAR-3, OVCA 429, and OVCA 433. Two additional cell lines produced PA activities that were tPA-like if judged by only one of the two criteria. Thus, Caov-4 cells produced a PA which comigrated with tPA, yet displayed no fibrin-dependent characteristics. Conversely, SK-OV-3 cells produced a fibrin-dependent PA, yet a band comigrating with tPA was not seen on SDS-PAGE zymography. Two lines derived from primary and ascitic sites from the same patient (A121 and A121[as], respectively) produced PAs with markedly different characteristics. Thus, PA produced by A121 cells was 100% UK-like, while that produced by A121[as] cells was >90% tPA-like. Also, the total PA activity secreted by A121 cells was four times that secreted by A121[as] cells. In addition to bands comigrating with UK or tPA, all of the cell lines except Caov-3 and NIH:OVCAR-3 displayed higher molecular weight PA activities suggestive of the SDS-stable complexes between PAs and PA inhibitors reported in other cell types. While our results indicate that PA production may be a general characteristic of ovarian carcinoma cells in culture, individual patterns of UK and tPA production appear to be complex and vary from cell line to cell line. The precise characteristics of PA production in a given cell line may therefore depend on currently unidentified characteristics of the original tumor.