EXPRESSION AND INDUCTION OF CYTOCHROME-P-450 1A1 AND P-450 2D SUBFAMILY IN THE RAT GLIOMA C6 CELL-LINE

The cytochrome P-450 (P-450) monooxygenase system can catalyze the oxi dation of a wide variety of endogenous and exogenous compounds, includ ing steroid hormones, fatty acids, drugs and pollutants. The functions of this system are as diverse as the substrates. Though this enzyme s ystem has the highest level of activity in the liver, it is present in other tissues, including brain. In this study, we have established th e rat glioma C6 cell line as an in vitro model system to examine the e xpression and induction of P-450 1A1 and the P-450 2D subfamily. Rat g lioma C6 cells were treated with P-450 inducers phenobarbital (PB) or benzo[a]anthracene (BA). The presence of P-450 1A1 and 2D1-5 was detec ted by reverse transcription followed by polymerase chain reaction (RT -PCR) and confirmed by restriction enzyme digestion. The induction of P-450 1A1 and 2D1-5 was quantified using competitive PCR. Although P-4 50 2D1-5 do not seem to be affected by PB or BA treatment, tenfold ind uction of P-450 1A1 mRNA after BA treatment was detected. Western blot analysis of microsomal preparations of glioma C6 cells demonstrated t he presence of P-450 1A1 at the protein level. ELISAs showed that BA i nduces P-450 1A1 proteins 7.3-fold. These experiments provide further evidence that the rat glioma C6 cell line contains an active cytochrom e P-450 monooxygenase system which can be induced by P-450 inducers. I n summary, we believe the presence of the cytochrome P-450 monooxygena se system in glial cells of the brain may be important in chemotherapy and carcinogenesis of brain tumors. (C) 1997 Elsevier Science B.V.