Differential sensitivity of human prostatic cancer cell lines to the effects of protein kinase and phosphatase inhibitors.

We investigated the effect of protein kinase and phosphatase inhibitors on the growth of six human prostatic cancer cell lines: DU145, PC3, ND1, LNCaP, ALVA31 and JCA1. We studied okadaic acid and sodium orthovanadate as serine/threonine and tyrosine protein phosphatase inhibitors, respectively, and staurosporin and genistein as a serine/threonine and tyrosine protein kinase inhibitors, respectively. All inhibitors examined exhibited a dose-dependent growth inhibitory effect on prostatic cancer cell lines. Our data indicate that prostatic cancer cell lines express unique biochemical properties since the degree of growth inhibition varied greatly and was dependent on the specific cell line and inhibitor studied. In addition, we found that surface expression of endoglin (CD105) changed by treatment with all inhibitors in most of the cell lines. These data also indicate that endoglin appears to be involved both in protein phosphatase and kinase mediated phosphoprotein turnover.