IMMUNOHISTOCHEMICAL LOCALIZATION OF CYTOCHROME-P450 3A IN HUMAN PULMONARY CARCINOMAS AND NORMAL BRONCHIAL TISSUE

The cytochrome P450 (CYP) enzymes metabolize drugs and other xenobioti cs in liver and also in some extrahepatic tissues. We have studied the expression and localization of CYP3A in primary lung rumours and norm al lung tissue from the same patients. Thirty-two patients undergoing partial or total lung resection for therapy of primary pulmonary carci noma were included in this study. Immunohistochemical staining for CYP 3A was performed with a modification of the ABC technique. Eight of th e 32 cases of primary pulmonary carcinoma showed expression of CYP3A. In 12 of the 32 cases of normal tissue, the seromucous glands were pos itive for CYP3A. The bronchial epithelium was positive for CYP3A in 11 cases. We observed no correlation between CYP3A expression in tumour tissue and that in seromucous glands or bronchial epithelium. We concl ude that CYP3A is present in both normal and cancerous lung tissue. Ou r findings suggest, however, no co-expression of CYP3A in lung cancer.