Alleviation of benzo[a]pyrene-diolepoxide-DNA damage in human lung carcinoma by glutathione S-transferase M2

• Published in: DNA repair 2005-04, Vol.4 (4), p.493-502
• Main Authors: Weng, Mao-Wen, Hsiao, Yi-Min, Chiou, Hui-Ling, Yang, Shun-Fa, Hsieh, Yih-Shou, Cheng, Ya-Wen, Yang, Chieh-Hsiang, Ko, Jiunn-Liang
• Format: Article
• Language: English
• Subjects: 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide - toxicity; Bacteriology; Base Sequence; Biological and medical sciences; BPDE adduct; Cell Line, Tumor; DNA Adducts; DNA damage; DNA Damage - drug effects; DNA Primers; Enzyme-Linked Immunosorbent Assay; Fundamental and applied biological sciences. Psychology; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Growth, nutrition, cell differenciation; GST-M2; Humans; Isoenzymes - genetics; Isoenzymes - metabolism; Kinetics; Lung Neoplasms; MDM2 splicing; Medical sciences; Microbiology; Molecular and cellular biology; Molecular genetics; Mutagenesis. Repair; Pneumology; Reverse Transcriptase Polymerase Chain Reaction; Tumors of the respiratory system and mediastinum
• ISSN: 1568-7864; 1568-7856
• DOI: 10.1016/j.dnarep.2004.12.006

Cellular detoxification is important for the routine removal of environmental and dietary carcinogens. Glutathione S-transferases (GST) are major cellular phase II detoxification enzymes. MRC-5 cells have been found to exhibit significantly higher GST activity than human H1355 cells. This study investigates whether GST-M2 activity acts as a critical determinant of the target dose of carcinogenic benzo[a]pyrene-diolepoxide (BPDE) and whether it has an effect on MDM2 splicing in the two cell lines. We used RT-PCR to clone Mu-class GST cDNA. Two forms of GST coming from the cell lines were characterized as GST-M2 (from MRC-5 cells) and GST-M4 (from H1355 cells). Nested-PCR showed that BPDE-induced MDM2 splicing had occurred in the H1355 cell line but not in normal MRC-5 cells. Furthermore, using nested-PCR and competitive ELISA, we found that in H1355 cells modified to stably overexpress GST-M2, splicing was abolished and BPDE adducts appeared in low abundance. In conclusion, exogenously overexpressed GST-M2 was effective in reducing BPDE-induced DNA damage in H1355 cells. The catalytic activity of GST-M2 may play an important future role in lowering the incidence of BPDE-induced DNA damage.