Induction of glutathione S-transferase, placental type in T9 glioma cells by dibutyryladenosine 3',5'-cyclic monophosphate and modification of its expression by naturally occurring isothiocyanates.

The effect of dibutyryladenosine 3',5'-cyclic monophosphate (dibutyryl cAMP) on the expression of glutathione S-transferase placental type (GST-P) was examined in rat glioma cell line using an immunohistochemical technique. Cultured T9 glioma cells were negative for GST-P activity under normal conditions. However, treatment with 1 mM dibutyryl cAMP produced GST-P expression in about 50% of the cells, as well as some morphological changes. The expression of GST-P was increased with addition of dibutyryl cAMP together with 1 microgram/ml allyl isothiocyanate (AITC) or 0.1 microgram/ml benzyl isothiocyanate (BITC). With these combinated treatments, almost all cultured cells showed a strong positive reaction for GST-P, although AITC or BITC alone elicited GST-P in only 5% of the cultured cells. The results of the present study indicate that dibutyryl cAMP causes functional as well as morphological differentiation of T9 glioma cells.