Glycine N-methyltransferase affects the metabolism of aflatoxin B1 and blocks its carcinogenic effect

Chia Hung Yen, Jung Hsien Hung, Yune Fang Ueng, Shih Ping Liu, Shih Yin Chen, Hsiao Han Liu, Teh Ying Chou, Ting Fen Tsai, Ramalakshmi Darbha, Ling Ling Hsieh, Yi Ming Arthur Chen

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Previously, we reported that glycine N-methyltransferase (GNMT) knockout mice develop chronic hepatitis and hepatocellular carcinoma (HCC) spontaneously. For this study we used a phosphoenolpyruvate carboxykinase promoter to establish a GNMT transgenic (TG) mouse model. Animals were intraperitoneally inoculated with aflatoxin B1 (AFB1) and monitored for 11 months, during which neither male nor female GNMT-TG mice developed HCC. In contrast, 4 of 6 (67%) male wild-type mice developed HCC. Immunofluorescent antibody test showed that GNMT was translocated into nuclei after AFB1 treatment. Competitive enzyme immunoassays indicated that after AFB1 treatment, the AFB1-DNA adducts formed in stable clones expressing GNMT reduced 51.4% compared to the vector control clones. Experiments using recombinant adenoviruses carrying GNMT cDNA (Ad-GNMT) further demonstrated that the GNMT-related inhibition of AFB1-DNA adducts formation is dose-dependent. HPLC analysis of the metabolites of AFB1 in the cultural supernatants of cells exposed to AFB1 showed that the AFM1 level in the GNMT group was significantly higher than the control group, indicating the presence of GNMT can enhance the detoxification pathway of AFB1. Cytotoxicity assay showed that the GNMT group had higher survival rate than the control group after they were treated with AFB1. Automated docking experiments showed that AFB1 binds to the S-adenosylmethionine binding domain of GNMT. Affinity sensor assay demonstrated that the dissociation constant for GNMT-AFB1 interaction is 44.9 μM. Therefore, GNMT is a tumor suppressor for HCC and it exerts protective effects in hepatocytes via direct interaction with AFB1, resulting in reduced AFB1-DNA adducts formation and cell death.

Original languageEnglish
Pages (from-to)296-304
Number of pages9
JournalToxicology and Applied Pharmacology
Volume235
Issue number3
DOIs
Publication statusPublished - Mar 15 2009
Externally publishedYes

Fingerprint

Glycine N-Methyltransferase
Aflatoxin B1
Metabolism
Hepatocellular Carcinoma
Transgenic Mice
Assays
Clone Cells
S-Adenosylmethionine
Detoxification
Control Groups
Phosphoenolpyruvate

Keywords

  • AFB metabolism
  • Detoxification
  • DNA adducts
  • Hepatocelluar carcinoma
  • Transgenic mouse model

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology

Cite this

Glycine N-methyltransferase affects the metabolism of aflatoxin B1 and blocks its carcinogenic effect. / Yen, Chia Hung; Hung, Jung Hsien; Ueng, Yune Fang; Liu, Shih Ping; Chen, Shih Yin; Liu, Hsiao Han; Chou, Teh Ying; Tsai, Ting Fen; Darbha, Ramalakshmi; Hsieh, Ling Ling; Chen, Yi Ming Arthur.

In: Toxicology and Applied Pharmacology, Vol. 235, No. 3, 15.03.2009, p. 296-304.

Research output: Contribution to journalArticle

Yen, CH, Hung, JH, Ueng, YF, Liu, SP, Chen, SY, Liu, HH, Chou, TY, Tsai, TF, Darbha, R, Hsieh, LL & Chen, YMA 2009, 'Glycine N-methyltransferase affects the metabolism of aflatoxin B1 and blocks its carcinogenic effect', Toxicology and Applied Pharmacology, vol. 235, no. 3, pp. 296-304. https://doi.org/10.1016/j.taap.2008.12.013
Yen, Chia Hung ; Hung, Jung Hsien ; Ueng, Yune Fang ; Liu, Shih Ping ; Chen, Shih Yin ; Liu, Hsiao Han ; Chou, Teh Ying ; Tsai, Ting Fen ; Darbha, Ramalakshmi ; Hsieh, Ling Ling ; Chen, Yi Ming Arthur. / Glycine N-methyltransferase affects the metabolism of aflatoxin B1 and blocks its carcinogenic effect. In: Toxicology and Applied Pharmacology. 2009 ; Vol. 235, No. 3. pp. 296-304.
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