L. Gervot et al., CYP3A5 IS THE MAJOR CYTOCHROME-P450 3A EXPRESSED IN HUMAN COLON AND COLONIC CELL-LINES, Environmental toxicology and pharmacology, 2(4), 1996, pp. 381-388
CYP3A is known to be expressed in liver, small intestine and colon. Ho
wever, its isoform distribution (CYP3A4, 3A5 and 3A7) and inducibility
have not been clearly elucidated in the colon. Therefore, we analyzed
CYP3A in human colon and compared its expression and inducibility to
the human colonic cell lines HT29 and Caco2, which were used as models
. Patients suffered either from sigmoiditis or colonic adenocarcinoma.
Patients as well as HT29 and Caco2 cells were treated with rifampicin
. CYP3A protein expression was analyzed in the colon of patients and i
n the cells by immunoblot and by isoelectric focusing enabling separat
ion of CYP3A isoforms, while mRNA expression was determined using spec
ific reverse transcription-polymerase chain reaction. In both human co
lon and cells, CYP3A5 was the main isoform expressed at the protein an
d mRNA levels. Rifampicin treatment had no effect on CYP3A expression.
HT29 and Caco2 cells exhibiting the same CYP3A expression and inducib
ility might therefore be useful in vitro models for studying xenobioti
c metabolism in human colon.