Intestinal Human Colon Adenocarcinoma Cell Line LS180 Is an Excellent Model to Study Pregnane X Receptor, but Not Constitutive Androstane Receptor, Mediated CYP3A4 and Multidrug Resistance Transporter 1 Induction: Studies with Anti-Human Immunodeficiency Virus Protease Inhibitors

• Published in: Drug metabolism and disposition Vol. 36; no. 6; pp. 1172 - 1180
• Main Authors: GUPTA, Anshul, MUGUNDU, Ganesh M, DESAI, Pankaj B, THUMMEL, Kenneth E, UNADKAT, Jashvant D
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Pharmacology and Experimental Therapeutics 01.06.2008
• Subjects: ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1 - genetics; Biological and medical sciences; Cell Line, Tumor; Colonic Neoplasms; Cytochrome P-450 CYP3A - genetics; Cytochrome P-450 CYP3A - metabolism; Gastroenterology. Liver. Pancreas. Abdomen; HIV Protease Inhibitors - pharmacology; Humans; Medical sciences; Pharmacology. Drug treatments; Pregnane X Receptor; Receptors, Cytoplasmic and Nuclear - genetics; Receptors, Steroid - genetics; Receptors, Steroid - metabolism; RNA, Messenger - metabolism; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Transcription Factors - genetics; Transcription, Genetic - drug effects; Tumors; Isozyme; Model study; Constitutive androstane receptor; Colon cancer; Multiple resistance; Established cell line; Intestinal disease; Tumor cell; Carrier protein; Human; Treatment resistance; Colon adenocarcinoma; Digestive system; Enzyme; Induction; Cytochrome P450; Pregnane X receptor; Gut; Retroviridae; Malignant tumor; Lentivirus; In vitro; Colonic disease; Virus; Cell line; Digestive diseases; Human immunodeficiency virus; Protease inhibitor; Cancer
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.107.018689

Lack of an established cell line model to study induction of cytochromes P450 (P450s) and drug transporters poses a challenge in predicting in vivo drug-drug interactions. Although not well characterized, LS180 cells could be an excellent cell line to study induction of P450s and transporters because they express pregnane X receptor (PXR). Therefore, as part of a larger study of in vitro to in vivo prediction of inductive drug interactions, we determined induction of various P450s and drug transporters by the anti-human deficiency virus protease inhibitors (PIs) and the prototypic inducer, rifampin, in LS180 cells. Among these proteins, the various PIs significantly induced ( n = 3–5) only CYP3A4 and multidrug resistance transporter 1 (MDR1) transcripts (2- to 50-fold). CYP3A4 activity (1′-hydroxymidazolam formation) was increased (2-fold) by rifampin (10 μM) but was reduced by the PIs (1.5- to 7-fold). Surprisingly, constitutive androstane receptor 1 (CAR1) was not found to be expressed in these cells. Additionally, using a reporter assay, we found that PIs did not activate CAR3 (the natural splice variant of CAR1) but significantly activated PXR (2- to 24-fold), which correlated well with induction of CYP3A4 and MDR1 transcripts (∼ r = 0.9). Furthermore, in a PXR-knockdown stable LS180 cell line, induction of CYP3A4 and MDR1 mRNA after treatment with PIs and rifampin was significantly reduced (1.4- to 5-fold) compared with that in PXR nonsilenced cells. Based on these data, we conclude that LS180 cells could be used as a readily available, high-throughput cell line to screen for PXR-mediated induction of CYP3A4 and MDR1 transcripts. These data also indicate that the majority of the PIs are likely to produce intestinal drug-drug interactions by inactivating or inhibiting CYP3A enzymes even though they induce CYP3A4 and MDR1 transcripts via PXR.