Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation

A potential biomarker for human sensitivity to alkylating agents

Meixiang Xu, Ilona Nekhayeva, Courtney E. Cross, Catherine M. Rondelli, Jeffrey K. Wickliffe, Sherif Abdel-Rahman

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The O6-methylguanine-DNA methyltransferase gene (MGMT) encodes the direct reversal DNA repair protein that removes alkyl adducts from the O6 position of guanine. Several single-nucleotide polymorphisms (SNPs) exist in the MGMT promoter/enhancer (P/E) region. However, the haplotype structure encompassing these SNPs and their functional/biological significance are currently unknown. We hypothesized that MGMT P/E haplotypes, rather than individual SNPs, alter MGMT transcription and can thus alter human sensitivity to alkylating agents. To identify the haplotype structure encompassing the MGMT P/E region SNPs, we sequenced 104 DNA samples from healthy individuals and inferred the haplotypes using the data generated. We identified eight SNPs in this region, namely T7C (rs180989103), T135G (rs1711646), G290A (rs61859810), C485A (rs1625649), C575A (rs113813075), G666A (rs34180180), C777A (rs34138162) and C1099T (rs16906252). Phylogenetics and Sequence Evolution analysis predicted 21 potential haplotypes that encompass these SNPs ranging in frequencies from 0.000048 to 0.39. Of these, 10 were identified in our study population as 20 paired haplotype combinations. To determine the functional significance of these haplotypes, luciferase reporter constructs representing these haplotypes were transfected into glioblastoma cells and their effect on MGMT promoter activity was determined. Compared with the most common (reference) haplotype 1, seven haplotypes significantly upregulated MGMT promoter activity (18-119% increase; P< 0.05), six significantly downregulated MGMT promoter activity (29-97% decrease; P < 0.05) and one haplotype had no effect. Mechanistic studies conducted support the conclusion that MGMT P/E haplotypes, rather than individual SNPs, differentially regulate MGMT transcription and could thus play a significant role in human sensitivity to environmental and therapeutic alkylating agents.

Original languageEnglish (US)
Article numberbgt355
Pages (from-to)564-571
Number of pages8
JournalCarcinogenesis
Volume35
Issue number3
DOIs
StatePublished - 2014

Fingerprint

Alkylating Agents
Methyltransferases
Genetic Promoter Regions
Haplotypes
Biomarkers
DNA
Single Nucleotide Polymorphism
Genes
Guanine
Glioblastoma
Luciferases
DNA Repair
Sequence Analysis
Down-Regulation

ASJC Scopus subject areas

  • Cancer Research

Cite this

Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation : A potential biomarker for human sensitivity to alkylating agents. / Xu, Meixiang; Nekhayeva, Ilona; Cross, Courtney E.; Rondelli, Catherine M.; Wickliffe, Jeffrey K.; Abdel-Rahman, Sherif.

In: Carcinogenesis, Vol. 35, No. 3, bgt355, 2014, p. 564-571.

Research output: Contribution to journalArticle

Xu, Meixiang ; Nekhayeva, Ilona ; Cross, Courtney E. ; Rondelli, Catherine M. ; Wickliffe, Jeffrey K. ; Abdel-Rahman, Sherif. / Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation : A potential biomarker for human sensitivity to alkylating agents. In: Carcinogenesis. 2014 ; Vol. 35, No. 3. pp. 564-571.
@article{9162c27b80ba4da9bdcb9fca11ee048b,
title = "Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation: A potential biomarker for human sensitivity to alkylating agents",
abstract = "The O6-methylguanine-DNA methyltransferase gene (MGMT) encodes the direct reversal DNA repair protein that removes alkyl adducts from the O6 position of guanine. Several single-nucleotide polymorphisms (SNPs) exist in the MGMT promoter/enhancer (P/E) region. However, the haplotype structure encompassing these SNPs and their functional/biological significance are currently unknown. We hypothesized that MGMT P/E haplotypes, rather than individual SNPs, alter MGMT transcription and can thus alter human sensitivity to alkylating agents. To identify the haplotype structure encompassing the MGMT P/E region SNPs, we sequenced 104 DNA samples from healthy individuals and inferred the haplotypes using the data generated. We identified eight SNPs in this region, namely T7C (rs180989103), T135G (rs1711646), G290A (rs61859810), C485A (rs1625649), C575A (rs113813075), G666A (rs34180180), C777A (rs34138162) and C1099T (rs16906252). Phylogenetics and Sequence Evolution analysis predicted 21 potential haplotypes that encompass these SNPs ranging in frequencies from 0.000048 to 0.39. Of these, 10 were identified in our study population as 20 paired haplotype combinations. To determine the functional significance of these haplotypes, luciferase reporter constructs representing these haplotypes were transfected into glioblastoma cells and their effect on MGMT promoter activity was determined. Compared with the most common (reference) haplotype 1, seven haplotypes significantly upregulated MGMT promoter activity (18-119{\%} increase; P< 0.05), six significantly downregulated MGMT promoter activity (29-97{\%} decrease; P < 0.05) and one haplotype had no effect. Mechanistic studies conducted support the conclusion that MGMT P/E haplotypes, rather than individual SNPs, differentially regulate MGMT transcription and could thus play a significant role in human sensitivity to environmental and therapeutic alkylating agents.",
author = "Meixiang Xu and Ilona Nekhayeva and Cross, {Courtney E.} and Rondelli, {Catherine M.} and Wickliffe, {Jeffrey K.} and Sherif Abdel-Rahman",
year = "2014",
doi = "10.1093/carcin/bgt355",
language = "English (US)",
volume = "35",
pages = "564--571",
journal = "Carcinogenesis",
issn = "0143-3334",
publisher = "Oxford University Press",
number = "3",

}

TY - JOUR

T1 - Influence of promoter/enhancer region haplotypes on MGMT transcriptional regulation

T2 - A potential biomarker for human sensitivity to alkylating agents

AU - Xu, Meixiang

AU - Nekhayeva, Ilona

AU - Cross, Courtney E.

AU - Rondelli, Catherine M.

AU - Wickliffe, Jeffrey K.

AU - Abdel-Rahman, Sherif

PY - 2014

Y1 - 2014

N2 - The O6-methylguanine-DNA methyltransferase gene (MGMT) encodes the direct reversal DNA repair protein that removes alkyl adducts from the O6 position of guanine. Several single-nucleotide polymorphisms (SNPs) exist in the MGMT promoter/enhancer (P/E) region. However, the haplotype structure encompassing these SNPs and their functional/biological significance are currently unknown. We hypothesized that MGMT P/E haplotypes, rather than individual SNPs, alter MGMT transcription and can thus alter human sensitivity to alkylating agents. To identify the haplotype structure encompassing the MGMT P/E region SNPs, we sequenced 104 DNA samples from healthy individuals and inferred the haplotypes using the data generated. We identified eight SNPs in this region, namely T7C (rs180989103), T135G (rs1711646), G290A (rs61859810), C485A (rs1625649), C575A (rs113813075), G666A (rs34180180), C777A (rs34138162) and C1099T (rs16906252). Phylogenetics and Sequence Evolution analysis predicted 21 potential haplotypes that encompass these SNPs ranging in frequencies from 0.000048 to 0.39. Of these, 10 were identified in our study population as 20 paired haplotype combinations. To determine the functional significance of these haplotypes, luciferase reporter constructs representing these haplotypes were transfected into glioblastoma cells and their effect on MGMT promoter activity was determined. Compared with the most common (reference) haplotype 1, seven haplotypes significantly upregulated MGMT promoter activity (18-119% increase; P< 0.05), six significantly downregulated MGMT promoter activity (29-97% decrease; P < 0.05) and one haplotype had no effect. Mechanistic studies conducted support the conclusion that MGMT P/E haplotypes, rather than individual SNPs, differentially regulate MGMT transcription and could thus play a significant role in human sensitivity to environmental and therapeutic alkylating agents.

AB - The O6-methylguanine-DNA methyltransferase gene (MGMT) encodes the direct reversal DNA repair protein that removes alkyl adducts from the O6 position of guanine. Several single-nucleotide polymorphisms (SNPs) exist in the MGMT promoter/enhancer (P/E) region. However, the haplotype structure encompassing these SNPs and their functional/biological significance are currently unknown. We hypothesized that MGMT P/E haplotypes, rather than individual SNPs, alter MGMT transcription and can thus alter human sensitivity to alkylating agents. To identify the haplotype structure encompassing the MGMT P/E region SNPs, we sequenced 104 DNA samples from healthy individuals and inferred the haplotypes using the data generated. We identified eight SNPs in this region, namely T7C (rs180989103), T135G (rs1711646), G290A (rs61859810), C485A (rs1625649), C575A (rs113813075), G666A (rs34180180), C777A (rs34138162) and C1099T (rs16906252). Phylogenetics and Sequence Evolution analysis predicted 21 potential haplotypes that encompass these SNPs ranging in frequencies from 0.000048 to 0.39. Of these, 10 were identified in our study population as 20 paired haplotype combinations. To determine the functional significance of these haplotypes, luciferase reporter constructs representing these haplotypes were transfected into glioblastoma cells and their effect on MGMT promoter activity was determined. Compared with the most common (reference) haplotype 1, seven haplotypes significantly upregulated MGMT promoter activity (18-119% increase; P< 0.05), six significantly downregulated MGMT promoter activity (29-97% decrease; P < 0.05) and one haplotype had no effect. Mechanistic studies conducted support the conclusion that MGMT P/E haplotypes, rather than individual SNPs, differentially regulate MGMT transcription and could thus play a significant role in human sensitivity to environmental and therapeutic alkylating agents.

UR - http://www.scopus.com/inward/record.url?scp=84895831328&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84895831328&partnerID=8YFLogxK

U2 - 10.1093/carcin/bgt355

DO - 10.1093/carcin/bgt355

M3 - Article

VL - 35

SP - 564

EP - 571

JO - Carcinogenesis

JF - Carcinogenesis

SN - 0143-3334

IS - 3

M1 - bgt355

ER -