Differential Impacts of Phenol Red on Benzo[a]pyrene and Dexamethasone-Modified Cytochrome P450s in Human Cancer Cells

<b>Background and Objective:</b> Phenol red, the pH indicator in cell culture media, influences the expression of cytochrome P450s (CYPs) in cell lines. This study aimed to examine how phenol red modified CYP induction by benzo[<i>a</i>]pyrene and dexamethasone in human hepatocarcinoma (HepG2), colorectal adenocarcinoma (Caco-2) and choriocarcinoma (BeWo) cells. <b>Materials and Methods:</b> The cells (1×10<sup>5</sup> cells/well in a 24-well plate) were incubated with benzo[<i>a</i>]pyrene (0.1, 1 and 10 μM) or dexamethasone (1, 5 and 10 μM) in either phenol red or phenol red-free media for 24 hrs. The mRNA expression of CYPs was determined by Real-Time Polymerase Chain Reaction (RT/qPCR). <b>Results:</b> Phenol red enhanced expression of benzo[<i>a</i>]pyrene-induced CYP1A2 inHepG2 and BeWo cells and suppressed benzo[<i>a</i>]pyrene-induced CYP2A6 expression in HepG2 and Caco-2 cells, benzo[<i>a</i>]pyrene induced CYP2B6 expression in HepG2 cells and benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A4 expression in HepG2 and Caco-2 cells. The expression of CYP3A5 was affected differently in HepG2 and Caco-2 cell lines. Phenol red enhanced benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A5 expression in Caco-2 cells but suppressed benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A5 expression in HepG2 cells. <b>Conclusion:</b> Phenol red differentially influenced expression of benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP1A2, CYP2A6, CYP2B6, CYP3A4 and CYP3A5 mRNAs in HepG2, Caco-2 and BeWo cells. Therefore, the inclusion of phenol red in cell culture media is of concern in studies of drug and xenobiotic metabolism via CYPs in human cell line models.