Correlation of MLH1 and MGMT methylation levels between peripheral blood leukocytes and colorectal tissue DNA samples in colorectal cancer patients

  • Authors:
    • Xia Li
    • Yibaina Wang
    • Zuoming Zhang
    • Xiaoping Yao
    • Jie Ge
    • Yashuang Zhao
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  • Published online on: August 23, 2013     https://doi.org/10.3892/ol.2013.1543
  • Pages: 1370-1376
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Abstract

CpG island methylation in the promoter regions of the DNA mismatch repair gene mutator L homologue 1 (MLH1) and DNA repair gene O6‑methylguanine‑DNA methyltransferase (MGMT) genes has been shown to occur in the leukocytes of peripheral blood and colorectal tissue. However, it is unclear whether the methylation levels in the blood leukocytes and colorectal tissue are correlated. The present study analyzed and compared the levels of MGMT and MLH1 gene methylation in the leukocytes of peripheral blood and colorectal tissues obtained from patients with colorectal cancer (CRC). The methylation levels of MGMT and MLH1 were examined using methylation‑sensitive high‑resolution melting (MS‑HRM) analysis. A total of 44 patients with CRC were selected based on the MLH1 and MGMT gene methylation levels in the leukocytes of the peripheral blood. Corresponding colorectal tumor and normal tissues were obtained from each patient and the DNA methylation levels were determined. The correlation coefficients were evaluated using Spearman's rank test. Agreement was determined by generalized κ‑statistics. Spearman's rank correlation coefficients (r) for the methylation levels of the MGMT and MLH1 genes in the leukocytes of the peripheral blood and normal colorectal tissue were 0.475 and 0.362, respectively (P=0.001 and 0.016, respectively). The agreement of the MGMT and MLH1 gene methylation levels in the leukocytes of the peripheral blood and normal colorectal tissue were graded as fair and poor (κ=0.299 and 0.126, respectively). The methylation levels of MGMT and MLH1 were moderately and weakly correlated between the patient‑matched leukocytes and the normal colorectal tissue, respectively. Blood‑derived DNA methylation measurements may not always represent the levels of normal colorectal tissue methylation.
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November 2013
Volume 6 Issue 5

Print ISSN: 1792-1074
Online ISSN:1792-1082

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Spandidos Publications style
Li X, Wang Y, Zhang Z, Yao X, Ge J and Zhao Y: Correlation of MLH1 and MGMT methylation levels between peripheral blood leukocytes and colorectal tissue DNA samples in colorectal cancer patients. Oncol Lett 6: 1370-1376, 2013
APA
Li, X., Wang, Y., Zhang, Z., Yao, X., Ge, J., & Zhao, Y. (2013). Correlation of MLH1 and MGMT methylation levels between peripheral blood leukocytes and colorectal tissue DNA samples in colorectal cancer patients. Oncology Letters, 6, 1370-1376. https://doi.org/10.3892/ol.2013.1543
MLA
Li, X., Wang, Y., Zhang, Z., Yao, X., Ge, J., Zhao, Y."Correlation of MLH1 and MGMT methylation levels between peripheral blood leukocytes and colorectal tissue DNA samples in colorectal cancer patients". Oncology Letters 6.5 (2013): 1370-1376.
Chicago
Li, X., Wang, Y., Zhang, Z., Yao, X., Ge, J., Zhao, Y."Correlation of MLH1 and MGMT methylation levels between peripheral blood leukocytes and colorectal tissue DNA samples in colorectal cancer patients". Oncology Letters 6, no. 5 (2013): 1370-1376. https://doi.org/10.3892/ol.2013.1543