Correlation of MLH1 polymorphisms, survival statistics, in silico assessment and gene downregulation with clinical outcomes among breast cancer cases
- 39 Downloads
This study aimed to investigate the role of MLH1 polymorphisms, respective protein structure prediction, survival analysis, related clinicopathological details and MLH1 expression in breast cancer (BC). Genotyping of selected SNPs in BC patients (493) and age matched controls (387) were performed by Tetra–ARMS PCR. Gene expression among breast tumors (127) and adjacent control tissues were analysed using reverse transcriptase PCR (RT-PCR) and immunohistochemistry. Statistical analysis was performed by SPSS and MedCalc. Conditional logistic regression analysis was applied to compute the odds ratio and confidence interval. Phyre2 and I-TASSER were used to generate MLH1 protein structures and verified by a variety of computational tools. Genotyping illustrated that MLH1 polymorphisms (rs63749795 and rs63749820) were significantly associated (P ≤ 0.05) with risk of developing BC. Down regulation of MLH1 gene expression/loss of the MLH1 protein (OR 12; CI 2.8–53.1) was observed in BC cases, illustrating its potential role in disease development. Moreover, loss of the MLH1 protein was found to be associated with higher grade cancer (P = 0.02) and lymph node positivity (P = 0.03), highlighting its essential role, as a component of the mismatch repair (MMR) machinery. Bioinformatics analysis confirmed that nonsense mutations produce a truncated MLH1 protein, causing a reduction in MMR efficiency. No association between MLH1 polymorphisms and overall and progression free survival statistics was observed among BC cases, possibly due to short follow–up study. Results at DNA, RNA and protein levels, along with in silico analysis, highlights the potential role of MLH1 in DNA repair mechanisms, within BC. Therefore, it was concluded that MLH1 may contribute towards BC development and progression.
KeywordsMLH1 ARMS PCR Breast cancer Polymorphisms Expression Survival analysis
We would like to thank all the patients, their family members and colleagues at Armed Forces Institute of Pathology for their kind help and support.
No support or funding is available for this study.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflict of interest.
- 1.Siegel RL, Miller KD, Jemal A (2018) Cancer statistics, 2018. CA: Cancer J Clin 68(1):7–30Google Scholar
- 3.DeSantis CE, Fedewa SA, Goding Sauer A, Kramer JL, Smith RA, Jemal A (2016) Breast cancer statistics, 2015: convergence of incidence rates between black and white women. CA: Cancer J Clin 66(1):31–42Google Scholar
- 7.Buchanan DD, Tan YY, Walsh MD, Clendenning M, Metcalf AM, Ferguson K, Arnold ST, Thompson BA, Lose FA, Parsons MT (2014) Tumor mismatch repair immunohistochemistry and DNA MLH1 methylation testing of patients with endometrial cancer diagnosed at age younger than 60 years optimizes triage for population-level germline mismatch repair gene mutation testing. J Clin Oncol 32(2):90CrossRefGoogle Scholar
- 24.Eisenberg D, Lüthy R, Bowie JU (1997)  VERIFY3D: assessment of protein models with three-dimensional profiles. Methods in enzymology, vol 277. Elsevier, Amsterdam, pp 396–404Google Scholar
- 29.Chollet-Hinton L, Anders CK, Tse C-K, Bell MB, Yang YC, Carey LA, Olshan AF, Troester MA (2016) Breast cancer biologic and etiologic heterogeneity by young age and menopausal status in the Carolina Breast Cancer Study: a case-control study. Breast Cancer Res 18(1):79. https://doi.org/10.1186/s13058-016-0736-y CrossRefPubMedPubMedCentralGoogle Scholar
- 33.Wang T, Stadler ZK, Zhang L, Weiser MR, Basturk O, Hechtman JF, Vakiani E, Saltz LB, Klimstra DS, Shia J (2018) Immunohistochemical null-phenotype for mismatch repair proteins in colonic carcinoma associated with concurrent MLH1 hypermethylation and MSH2 somatic mutations. Fam Cancer 17(2):225–228CrossRefGoogle Scholar