Effect of hyperthermia and protein kinase C inhibitors on DNA synthesis and cell proliferation on Ehrlich ascites tumour cells in vitro.

Effect of hyperthermia and/or protein kinase inhibitors on DNA synthesis and cell proliferation was investigated in Ehrlich ascites tumour cells in vitro. Both H-7 and H-8, potent inhibitors of protein kinase C, suppressed DNA synthesis significantly, but HA1004, an inhibitor of cAMP- and cGMP-dependent protein kinase, did not. Hyperthermia increased greatly the suppressive activity of H-7 and H-8 but not that of HA1004. H-7 also inhibited cell growth. These results suggest that the inhibition of protein kinase C enhances the suppression of DNA synthesis and the proliferation of tumour cells by hyperthermia.