Expression of protein kinase C in human renal cell carcinoma cells with inherent resistance to doxorubicin.

The expression of protein kinase C (PKC) was analyzed in 18 primary cell cultures of human renal cell carcinomas by means of immunocytochemistry. We found that a high PKC expression significantly correlates with both resistance to doxorubicin and high P-glycoprotein expression. These data support the hypothesis that PKC is involved in inherent drug-resistance by phosphorylation and regulation of P-glycoprotein.