CYP3A4 overexpression enhances apoptosis induced by anticancer agent imidazoacridinone C-1311, but does not change the metabolism of C-1311 in CHO cells

Aim： To examine whether CYP3A4 overexpression influences the metabolism of anticancer agent imidazoacridinone C-1311 in CHO cells and the responses of the cells to C-1311. Methods： Wild type CHO cells （CHO-WT）, CHO cells overexpressing cytochrome P450 reductase （CPR） [CHO-HR] and CHO cells coexpressing CPR and CYP3A4 （CHO-HR-3A4） were used. Metabolic transformation of C-1311 and CYP3A4 activity were measured using RP-HPLC. Flow cytometry analyses were used to examine cell cycle, caspase-3 activity and cell apoptosis. The expression of pH 6.0-dependent β-galactosidase （SA-β-gal） was studied to evaluate accelerated senescence. ROS generation was analyzed with CM-H2 DCFDA staining. Results： CYP3A4 overexpression did not change the metabolism of C-1311 in CHO cells： the levels of all metabolites of C-1311 increased with the exposure time to a similar extent, and the differences in the peak level of the main metabolite M3 were statistically insignificant among the three CHO cell lines. In CHO？HR？3A4 cells, C-1311 effectively inhibited CYP3A4 activity without affecting CYP3A4 protein level. In the presence of C-1311, CHO-WT cells underwent rather stable G2/M arrest, while the two types of transfected cells only transiently accumulated at this phase. C-1311-induced apoptosis and necrosis in the two types of transfected cells occurred with a significantly faster speed and to a greater extent than in CHO-WT cells. Additionally, C-1311 induced ROS generation in the two types of transfected cells, but not in CHO-WT cells. Moreover, CHO？HR？3A4 cells that did not die underwent accelerated senescence. Conclusion： CYP3A4 overexpression in CHO cells enhances apoptosis induced by C-1311, whereas the metabolism of C-1311 is minimal and does not depend on CYP3A4 expression.