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

Mol Carcinog. 2002 Mar;33(3):156-62.


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 microM (+)-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 microM [(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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / metabolism*
  • 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / toxicity*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • Animals
  • Carcinogens / toxicity*
  • Cell Line
  • DNA Damage*
  • Dogs
  • Glutathione / metabolism*
  • Glutathione Transferase / metabolism
  • Membrane Transport Proteins*
  • Microscopy, Confocal
  • Multidrug Resistance-Associated Proteins / genetics
  • Transfection


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Carcinogens
  • Membrane Transport Proteins
  • Multidrug Resistance-Associated Proteins
  • glutathione-BPDE conjugate
  • multidrug resistance-associated protein 2
  • 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
  • Glutathione Transferase
  • Glutathione
  • multidrug resistance-associated protein 1