The pleiotropic effect of TPA on in vitro invasion/migration of glioma and melanoma cell lines.

The invasion/migration of two cell lines, melanoma (MEW) and glioma (BT5C), and their counterparts treated for prolonged time with TPA were studied. On Western blots both cell lines expressed alpha, beta I protein kinase C isoforms, whereas beta II and gamma were not detected. The down-regulation of alpha and beta I PKC was observed in glioma cells after long treatment with TPA, whereas the same treatment of melanoma cells did not lead to PKC downregulation. The down-regulation of PKC was accompanied by stimulation of cell migration/invasion through Transwell chambers coated with collagen IV or fibronectin. In the case of melanoma cells treated with TPA, whose PKC was not down-regulated, the inhibition of migration/invasion was observed. The invasive properties of studied cells did not correlate with any conventional PKC isoform expression.