EXPRESSION OF GLUTATHIONE-S-TRANSFERASE P-FORM IN PRIMARY CULTURED RAT-LIVER PARENCHYMAL-CELLS BY COPLANAR POLYCHLORINATED BIPHENYL CONGENERS IS SUPPRESSED BY PROTEIN-KINASE INHIBITORS AND DEXAMETHASONE

Glutathione S-transferase P-form (GST-P, EC 2.5.1.18) mRNA was expressed by epidermal growth factor as well as by 3,4,5,3',4'-penta-chlorinated biphenyl (PenCB) in primary cultured rat liver parenchymal cells. The expression of GST-P was suppressed by inhibitors of protein kinase C and dexamethasone, an antagonist of AP-1 transcription factor activity, whereas expression of cytochrome P450IA2 by PenCB was not affected by these reagents. The AP-1 related transcription factor may be essential for the expression of GST-P by PenCB as also may be a protein kinase C type enzyme.