title: Inverse association between microRNA-124a and ABCC4 in HepG2 cells treated with antiretroviral drugs.
abstract: The ATP-binding cassette (ABC) super-family of drug transporters regulates efflux of xenobiotic compounds. The subfamily, multi-drug resistance proteins (MRPs) transports cyclic nucleotides and xenobiotics. Epigenetic modulation of drug transporters is scarcely described. The regulatory role of microRNA (miR)-124a on drug transporter gene ABCC4 was only recently reported. Our study investigated the differential regulation of miR-124a by nucleoside reverse transcriptase inhibitors (NRTIs): Zidovudine (AZT), Stavudine (d4T) and Tenofovir (TFV); at 24 h and 120 h treatments in HepG2 cells. ABCC4 mRNA (qPCR) and ABCC4 protein (western blot) were quantified. Cytotoxicity was evaluated by lactate dehydrogenase (LDH) levels. All NRTIs elevated miR-124a levels at 24 h, with a concomitant decline in ABCC4 mRNA levels (p<0.05). At 120 h, d4T and TFV elevated miR-124a and depleted ABCC4 mRNA levels (p<0.0001), while the inverse was observed with AZT (p<0.005). ABCC4 protein was increased by d4T and TFV at 24h. A significant reduction in protein levels was observed at 120 h in all three treatments (p<0.005). The disjoint in mRNA and protein levels is likely due to ABCC4 being a membrane bound protein. Following prolonged exposure, membrane integrity was compromised as evidenced by increased LDH leakage (p<0.005). We conclude antiretroviral drugs have varying effects on miR-124a and ABCC4.
authors.affiliation: a Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal , Durban , South Africa.
authors.forename: Savania
authors.initials: S
authors.lastname: Nagiah
authors.affiliation: a Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal , Durban , South Africa.
authors.forename: Alisa
authors.initials: A
authors.lastname: Phulukdaree
authors.affiliation: a Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal , Durban , South Africa.
authors.forename: Anil
authors.initials: A
authors.lastname: Chuturgoon
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D044966:Anti-Retroviral Agents / Q000494:pharmacology*; D056945:Hep G2 Cells; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D000068698:Tenofovir; D015215:Zidovudine
chemical_list: D018528:ATP-Binding Cassette Transporters; D044966:Anti-Retroviral Agents; D035683:MicroRNAs; D015215:Zidovudine; D000068698:Tenofovir
keywords: Cassette (ABC) super-family of drug transporters; HepG2 cells; NRTIs; microRNA-124a; multi-drug resistance proteins