Cellular Oncology

, Volume 39, Issue 5, pp 435–447 | Cite as

MGMT DNA repair gene promoter/enhancer haplotypes alter transcription factor binding and gene expression

  • Meixiang Xu
  • Courtney E. Cross
  • Jordan T. Speidel
  • Sherif Z. Abdel-Rahman
Original Paper



The O6-methylguanine-DNA methyltransferase (MGMT) protein removes O6-alkyl-guanine adducts from DNA. MGMT expression can thus alter the sensitivity of cells and tissues to environmental and chemotherapeutic alkylating agents. Previously, we defined the haplotype structure encompassing single nucleotide polymorphisms (SNPs) in the MGMT promoter/enhancer (P/E) region and found that haplotypes, rather than individual SNPs, alter MGMT promoter activity. The exact mechanism(s) by which these haplotypes exert their effect on MGMT promoter activity is currently unknown, but we noted that many of the SNPs comprising the MGMT P/E haplotypes are located within or in close proximity to putative transcription factor binding sites. Thus, these haplotypes could potentially affect transcription factor binding and, subsequently, alter MGMT promoter activity.


In this study, we test the hypothesis that MGMT P/E haplotypes affect MGMT promoter activity by altering transcription factor (TF) binding to the P/E region. We used a promoter binding TF profiling array and a reporter assay to evaluate the effect of different P/E haplotypes on TF binding and MGMT expression, respectively.


Our data revealed a significant difference in TF binding profiles between the different haplotypes evaluated. We identified TFs that consistently showed significant haplotype-dependent binding alterations (p ≤ 0.01) and revealed their role in regulating MGMT expression using siRNAs and a dual-luciferase reporter assay system.


The data generated support our hypothesis that promoter haplotypes alter the binding of TFs to the MGMT P/E and, subsequently, affect their regulatory function on MGMT promoter activity and expression level.


MGMT P/E haplotypes Transcription factor binding siRNA regulation Promoter activity 



This work was supported by grants from the National Institutes of Health (R03 NS065392-01 to S.A.R.; T-32-ES007254 to C.C. and J.S.) and the John Sealy Memorial Endowment fund for Biomedical Research (to S.A.R.). Additional partial support was provided by the NIEHS Center in Environmental Toxicology at the University of Texas Medical Branch funded through P30 ES006676, The Molecular Genomics Core (GMC) at the University of Texas Medical Branch, the Institute for Translational Sciences at the University of Texas Medical Branch, supported in part by a Clinical and Translational Science Award (8UL1TR000071) from the National Center for Research Resources, now the National Center for Advancing Translational Sciences, as well as the National Institutes of Health, R01 DA 030998-01 (to GDH/TN) and 2 U54 HD047891 (to GDH).

Compliance with ethical standards

Conflict of interest

None declared.

Supplementary material

13402_2016_286_MOESM1_ESM.pdf (189 kb)
ESM 1 (PDF 189 kb)
13402_2016_286_MOESM2_ESM.pdf (301 kb)
ESM 2 (PDF 300 kb)


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Copyright information

© International Society for Cellular Oncology 2016

Authors and Affiliations

  • Meixiang Xu
    • 1
  • Courtney E. Cross
    • 1
    • 2
  • Jordan T. Speidel
    • 1
  • Sherif Z. Abdel-Rahman
    • 1
  1. 1.Department of Obstetrics and Gynecology, Maternal-Fetal Pharmacology and Biodevelopment LaboratoriesUniversity of Texas Medical BranchGalvestonUSA
  2. 2.A.T. Still University School of Osteopathic MedicineMesaUSA

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