Immunohistochemical detection of P glycoprotein, glutathione S transferase and DNA topoisomerase II in human tumors.

The expression of the drug resistance markers P glycoprotein (P-170), glutathione S transferase-pi (GST-pi) and DNA topoisomerase II (Topo II) was analyzed in 16 human kidney carcinoma cell lines, 18 hematological malignancies, and 14 human breast carcinomas. We found a tendency for coexpression of increased P-170 and GST-pi and of increased P-170 and decreased Topo II expression in kidney carcinoma cell lines. A similar tendency was found between P-170 and GST-pi expression in breast carcinomas. In contrast, hematological malignancies did not show such a coexpression of resistance markers. Furthermore, we found interrelationships between the expression of resistance markers, resistance to doxorubicin or vincristine, and doubling times of kidney carcinoma cell lines. This indicates that the proliferative activity of tumor cells plays a role for the expression of resistance markers and the development of resistance to cytostatic drugs.