Role of glutathione conjugate efflux in cellular protection against benzo[a]pyrene-7,8-diol-9,10-epoxide–induced DNA damage

✍ Scribed by Sanjay K. Srivastava; Simon C. Watkins; Erin Schuetz; Shivendra V. Singh

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 277 KB
• Volume: 33
• Category: Article
• ISSN: 0899-1987
• DOI: 10.1002/mc.10032

✦ Synopsis

Abstract

Glutathione (GSH) conjugation of (+)‐anti‐benzo[a]pyrene‐7,8‐diol‐9,10‐epoxide [(+)‐anti‐BPDE], the activated metabolite of benzo[a]pyrene, is believed to be an important mechanism in detoxification of this environmental and dietary carcinogen. Here, we demonstrate that the intracellular accumulation of GSH conjugate of (+)‐anti‐BPDE (BPD‐SG) caused a statistically significant increase in (+)‐anti‐BPDE–induced DNA adduction. The relationship between intracellular accumulation of BPD‐SG and (+)‐anti‐BPDE–induced DNA adduction was studied using a canine kidney epithelial cell line (MDCKII) and its variants overexpressing multidrug resistance transporter (MDR1) or canalicular multispecific organic anion transporter (cMOAT; also known as multidrug resistance protein 2). MDR1 and cMOAT are implicated in ATP‐dependent efflux of anticancer drugs or GSH‐xenobiotic conjugates, or both. The GST activity toward (+)‐anti‐BPDE in parental MDCKII cells did not differ from that in subline overexpressing MDR1 (MDCKII‐MDR1) or cMOAT (MDCKII‐cMOAT). Intracellular accumulation of BPD‐SG, after a 5‐ or 10‐min incubation with 1 μM (+)‐anti‐BPDE, was significantly higher in parental (41‐ to 67‐fold) and MDCK II‐MDR1 cells (31‐ to 43‐fold) than in the MDCKII‐cMOAT cells. Interestingly, the levels of DNA adducts of (+)‐anti‐BPDE, after a 30‐min incubation with 0.1 or 0.5 μM ^3^H‐anti‐BPDE, were significantly higher (about 2.1‐ and 1.7‐fold, respectively) in parental cells than in the MDCKII‐cMOAT cells. The results of the present study indicate that in addition to GSH conjugation, the efflux of BPD‐SG may be essential for cellular protection against (+)‐anti‐BPDE–induced DNA damage. © 2002 Wiley‐Liss, Inc.