Stable expression of human cytochrome P450 3A4 in V79 cells and its application for metabolic profiling of ergot derivatives

Expression of human cytochrome P450 (CYP) in heterologous cells is a means of specifically studying the role of these enzymes in drug metabolism. The complete cDNA encoding CYP3A4 (PCN1) was inserted into an expression vector containing the strong myeloproliferative sarcoma virus promoter in combination with the enhancer of the cytomegalovirus and stably expressed in V79 Chinese hamster cells. The presence of genomically integrated CYP3A4 cDNA cell clones was confirmed by polymerase chain reaction analysis. Transcription was detected by reverse transcribed polymerase chain reaction analysis. Functional expression could be demonstrated by conversion of testosterone to the specific 6β-hydroxylated product. In recombinant V79 cells expressing CYP3A4 about 6% of the substrate was converted to 6β-hydroxytestosterone. The metabolism of two dopaminergic ergot derivatives was investigated in live recombinant V79 cells. Both lisuride and terguride were monodeethylated.