Sesamin: A Naturally Occurring Lignan Inhibits CYP3A4 by Antagonizing the Pregnane X Receptor Activation
Figure 3
Effect of sesamin (SSM), alone or sesamin in combination with rifampin, on CYP3A4 enzyme activity, mRNA expression, and protein expression. (a) Various concentrations of sesamin, alone or in combination with 20 μM rifampin, were added to cultured HepG2 cells for 48 h. CYP3A4 enzyme activities were measured by using P450-Glo assays with 50 μM luciferin-PFBE as a substrate. Values are presented as mean ± SD (); ### and *** as compared to DMSO-treated or 20-μM rifampin-treated cells, as appropriate. (b) HepG2 cells were treated with sesamin and rifampin, individually or in combination, for 48 h, mRNA was collected, and the expression of CYP3A4 and an internal control, β-actin, were analyzed using RT-PCR. Values were normalized relative to the expression of β-actin, with the CYP3A4 expression of DMSO-treated cells set at 100%. The results are as expressed as mean ± SD () of the relative expression of CYP3A4; * and *** as compared to DMSO-treated or 20-μM rifampin-treated cells, as indicated in the figure. (c) HepG2 cells were treated with sesamin and rifampin, individually or in combination, for 48 h. Whole cell extracts were harvested, and the expression of CYP3A4 and the internal control β-actin were analyzed using western blotting. (d) Quantitation of band intensity of the CYP3A4 protein was normalized to β-actin expression. The basal expression of the CYP3A4 protein was set at 100%. The values are presented as mean ± SD (); * as compared to DMSO-treated cells. (e) Quantitation of band intensity of CYP3A4 protein was normalized to the β-actin expression. The rifampin-induced CYP3A4 protein expression was set at 100%, and the values are presented as mean ± SD (); * as compared to rifampin-treated cells.
