Aberrant promoter region hypermethylation of hmlh1 Gene in Esophageal Cancer Patients of Kashmir valley

Introduction: The Study was a Case Control undertaken to understand the etiology of esophageal cancer in the population of Kashmiri origin. Esophageal cancer is one of the most prevalent cancers in Jammu and Kashmir region of India and has multi-factorial etiology involving dietary habits, genetic factors, and gene environmental interactions.In this study it was attempted to identify whether the altered methylation status of promoter region of Mismatch Repair (hmlh1) gene could be used as a molecular marker associated with esophageal carcinogenesis. Materials and Methods: Aberrant promoter region hypermethylation plays an important role in the progression of esophageal carcinoma. For evaluating the status of hmlh1promoter region hypermethylation and its association with Esophageal Cancer, methylation specific polymerase chain reaction (MS-PCR) was used. A total of 70 esophageal tissue specimens comprising 50 histopathologically confirmed tumor tissues and 20 histopathologically confirmed normal corresponding tissues as controls were collected for analysis in this study. DNA was extracted and treated with sodium bisulfite which converts unmethylated cytosines to uracil and does not affect methylated cytosines. The modified DNA was amplified in MS-PCR reaction by using methylated and unmethylated promoter specific primers. The MS-PCR products were run on 3% agarose and bands were visualized under UV light. Results: It was found that the frequency of promoter region hypermethylation of mismatch repair gene (hmlh1) in esophageal cancer cases was 56% and in histopathologically confirmed Normals it was 15%.Statistically the association of promoter region hypermethylation of mismatch repair gene (hmlh1) with esophageal cancer was found significant (p<0.05).Observing similar level of hmlh1 promoter hypermethylation in patients with Esophageal Cancer in this high risk region and comparing it with other parts of the world could support the hypothesis that a common molecular mechanism might be involved in tumorigenesis of Esophageal Cancer. As regards promoter hypermethylation status of mismatch repair gene hmlh1 shows a significant increase in promoter region hypermethylation of esophageal cancer patients of Kashmiri origin as compared to controls was observed. Keywords––Esophageal cancer, hmlh1, Hypermethylation, Mismatch repair, MS-PCR.