Endothelin-1 induces tumor proteinase activation and invasiveness of ovarian carcinoma cells.

Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpressed in primary and metastatic ovarian carcinoma. In these cells, ET-1 acts as an autocrine mitogenic and angiogenic factor selectively through the ET(A) receptor (ET(A)R). We investigated at mRNA and protein levels whether ET-1 could affect the expression and activation of metastasis-related proteinases and whether this process was associated with ovarian tumor cell invasion. ELISA, gelatin zymography, Western blot, and reverse transcription-PCR analyses demonstrated that in two ovarian carcinoma cell lines (HEY and OVCA 433), the expression of matrix metalloproteinase (MMP) -2, -9, -3, -7, and -13 was up-regulated and activated by ET-1. Moreover we observed that ET-1 was able to enhance the secretion and activation of membrane-type metalloproteinase-1, a critical mediator of invasiveness. The secretion of tissue inhibitor of metalloproteinase-1 and -2 was decreased by ET-1, which increased the net MMP/tissue inhibitor of metalloproteinase balance and the gelatinolytic capacity. In addition, ET-1 induced overexpression of urokinase-type plasminogen activator, its receptor, and plasminogen activator inhibitor type-1 and -2. Finally, we demonstrated that, in HEY and OVCA 433 cells, ET-1 dose-dependently increased migration and MMP-dependent invasion through Matrigel. BQ123, an antagonist of the ET(A)R, inhibited the ET-1-induced tumor protease activity and subsequent increase in cell migration and invasion. These findings demonstrate that ET-1 promotes ovarian carcinoma cell invasion, acting through the ET(A)R by up-regulating secretion and activation of multiple tumor proteinases. Therefore, ET-1 may represent a key component of more aggressive ligand-induced invasiveness of ovarian carcinoma.