In-vitro evaluation of chronic alcohol effects on expression of drug-metabolizing and drug-transporting proteins

• DOI: 10.1111/jphp.12124
• Publication Date: 2013-07-30T06:29:46Z
• Authors: Dirk Theile; Tobias T Schmidt; Walter E Haefeli; Johanna Weiss
• Keywords: 0301 basic medicine; Time Factors; Dose-Response Relationship, Drug; Ethanol; Cell Culture Techniques; Gene Expression; Organic Anion Transporters; 3. Good health; 03 medical and health sciences; Pentanols; Cytochrome P-450 Enzyme System; Cell Line, Tumor; Humans; ATP-Binding Cassette Transporters; ATP Binding Cassette Transporter, Subfamily B, Member 1

Abstract

Objectives In alcoholics without alcoholic liver disease, boosted drug elimination has been reported. However, mechanistic explanations for this phenomenon remain uncertain. In particular, data on the potential role of drug transporters are sparse.

Methods Using a well-established in-vitro model for induction of human drug-metabolizing and drug-transporting proteins, we evaluated the potency of ethanol and the major fermentation side-product isopentanol to alter expression and function of these proteins by quantitative real-time polymerase chain reaction, Western blotting and flow cytometry. P-glycoprotein (Pgp)-inhibiting properties of ethanol and isopentanol were investigated via calcein extrusion assay.

Key findings Ethanol and isopentanol significantly changed expression levels of drug-metabolizing and drug-transporting proteins that normalized within 2 weeks upon withdrawal. Cytochrome P-450 2C19 and Pgp were most strongly induced. Ethanol-induced Pgp at the messenger RNA (mRNA) (twofold to eightfold) and protein level (twofold), but not at the functional level. Both compounds did not inhibit Pgp.

Conclusions Ethanol is demonstrated to increase mRNA and protein expression of human drug transporters such as Pgp in vitro. Withdrawal of ethanol exposure causes return to non-induced conditions within weeks. Functional consequences of increased Pgp expression in alcoholics need to be evaluated by clinical trials applying selective Pgp substrates such as digoxin.