Functional effects of the MLH1-93G>A polymorphism on MLH1/EPM2AIP1 promoter activity

  • Authors:
    • Sheron Perera
    • Miralem Mrkonjic
    • James B. Rawson
    • Bharati Bapat
  • View Affiliations

  • Published online on: December 30, 2010     https://doi.org/10.3892/or.2010.1129
  • Pages: 809-815
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Abstract

Defective mismatch repair leads to the microsatellite instability (MSI) phenotype of colorectal cancer (CRC). We previously showed that the MLH1-93G>A promoter polymorphism is strongly associated with MSI tumours, suggesting a modifier role for this polymorphism in CRC. The MLH1 promoter is bi-directional with the EPM2AIP1 gene located on the antisense strand. In order to evaluate the functional effects of this polymorphism, we transfected a panel of CRC, endometrial cancer and non-tumourigenic cell lines with MLH1 luciferase promoter constructs. We used constructs in reverse orientation to assess the effect of this polymorphism on EPM2AIP1. The luciferase activities were compared using a two-sided Student's t-test. Electrophoretic mobility shift assays (EMSAs) were used to evaluate whether differential protein binding was responsible for the differences in promoter activity. We observed a higher level of activity with the -93G allele in all the cell lines observed; including the CRC cell line, HCT116 (P=0.002), the endometrial cancer cell line, HEC-1-A (P<0.001) and the normal colonic cell line, CCD-841-CoTr (P=0.002). This polymorphism also affected EPM2AIP1 transcription with the -93A allele demonstrating higher promoter activity in the HCT116 (P=0.007) and HEC-1-A (P=0.004) cells. The EMSA results suggest that this polymorphism alters the affinity of nuclear factors that bind to this region. Our findings indicate that the -93G>A polymorphism modifies the efficiency of MLH1/EPM2AIP1 transcription.

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March 2011
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Spandidos Publications style
Perera S, Mrkonjic M, Rawson JB and Bapat B: Functional effects of the MLH1-93G>A polymorphism on MLH1/EPM2AIP1 promoter activity. Oncol Rep 25: 809-815, 2011.
APA
Perera, S., Mrkonjic, M., Rawson, J.B., & Bapat, B. (2011). Functional effects of the MLH1-93G>A polymorphism on MLH1/EPM2AIP1 promoter activity. Oncology Reports, 25, 809-815. https://doi.org/10.3892/or.2010.1129
MLA
Perera, S., Mrkonjic, M., Rawson, J. B., Bapat, B."Functional effects of the MLH1-93G>A polymorphism on MLH1/EPM2AIP1 promoter activity". Oncology Reports 25.3 (2011): 809-815.
Chicago
Perera, S., Mrkonjic, M., Rawson, J. B., Bapat, B."Functional effects of the MLH1-93G>A polymorphism on MLH1/EPM2AIP1 promoter activity". Oncology Reports 25, no. 3 (2011): 809-815. https://doi.org/10.3892/or.2010.1129