Diindolylmethane, a naturally occurring compound, induces CYP3A4 and MDR1 gene expression by activating human PXR

Abstract

Activation of human pregnane X receptor (hPXR)-regulated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1) plays an important role in mediating adverse drug interactions. Given the common use of natural products as part of adjunct human health behavior, there is a growing concern about natural products for their potential to induce undesired drug interactions through the activation of hPXR-regulated CYP3A4 and MDR1. Here, we studied whether 3,3′-diindolylmethane (DIM), a natural health supplement, could induce hPXR-mediated regulation of CYP3A4 and MDR1 in human hepatocytes and intestinal cells. DIM, at its physiologically relevant concentrations, not only induced hPXR transactivation of CYP3A4 promoter activity but also induced gene expression of CYP3A4 and MDR1. DIM decreased intracellular accumulation of MDR1 substrate rhodamine 123, suggesting that DIM induces the functional expression of MDR1. Pharmacologic inhibition or genetic knockdown of hPXR resulted in attenuation of DIM induced CYP3A4 and MDR1 gene expression, suggesting that DIM induces CYP3A4 and MDR1 in an hPXR-dependent manner. Together, these results support our conclusion that DIM induces hPXR-regulated CYP3A4 and MDR1 gene expression. The inductive effects of DIM on CYP3A4 and MDR1 expression caution the use of DIM in conjunction with other medications metabolized and transported via CYP3A4 and MDR1, respectively.

Mg2+/Mn2+-Dependent Phosphatase 1A Is Involved in Regulating Pregnane X Receptor–Mediated Cytochrome p450 3A4 Gene Expression

“…Dimethylsulfoxide (DMSO), rifampicin, C 6 -ceramide, dihydro-C 6 -ceramide, and tumor necrosis factor a (TNFa) were purchased from Sigma-Aldrich (St. Louis, MO). The pcDNA3, FLAGpcDNA3, pcDNA3-hPXR, FLAG-pcDNA3-hPXR, pcDNA3-PPM1A, CDK2, cyclin E, pGL3-CYP3A4-luc, and pGL3-CMV-Renilla plasmids were previously described (Lin et al, 2008;Pondugula et al, 2010Pondugula et al, , 2014Shohat et al, 2012).…”

“…HepG2 human liver carcinoma cells and COS-7 monkey kidney fibroblasts were obtained from the American Type Culture Collection (Manassas, VA) and grown in Dulbecco's modified Eagle's medium (Lonza, Allendale, NJ) supplemented with 10% fetal bovine serum (HyClone, Logan, UT) (Pondugula et al, 2009a;Pondugula et al, 2014). HepG2 cells stably expressing hPXR and CYP3A4-luc (Lin et al, 2008) were maintained under the selection of G418.…”

“…Reverse transcription was performed with the QuantiTect Reverse Transcription Kit (Qiagen), and quantitative polymerase chain reaction was performed by using the QuantiTect SYBR Green Kit (Qiagen), iCycler iQ Real-Time PCR Detection System (Bio-Rad, Hercules, CA), and gene-specific primers of 18S rRNA (housekeeping gene), mouse PXR, and Cyp3a11 (Supplemental Table 1). Relative mRNA expression was calculated as described previously (Pondugula et al, 2010(Pondugula et al, , 2014.…”

“…The pregnane X receptor (PXR) target gene expression is regulated not only by endobiotics and xenobiotics Lehmann et al, 1998;Staudinger et al, 2006;Pondugula et al, 2014), but also by cellular signaling pathways (Pondugula et al, 2009b). For instance, p53, FOXO1, and nuclear factor-kB (NF-kB) interact with and regulate PXR function (Kodama et al, 2004;Gu et al, 2006;Xie and Tian, 2006;Elias et al, 2013;Kodama and Negishi, 2013).…”

Stearidonic acid, a plant-based dietary fatty acid, enhances the chemosensitivity of canine lymphoid tumor cells

“…The cells were then either untreated or treated with PBS, DMSO, ETOH, VCR, DOXO, SDA ± VCR, or SDA ± DOX for 24 h. Next, the CellTiter-Glo luminescent cell viability assays (Promega) were performed to determine the number of viable cells by quantifying the ATP present, which indicates the presence of metabolically active cells [23,24].…”