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Study of epigenetic changes in biomarkers of DNA extracted from human faeces for the diagnosis of colorectal cancer

Grant number: 12/20882-5
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): December 01, 2012
Effective date (End): November 30, 2013
Field of knowledge:Biological Sciences - Genetics
Principal Investigator:Jair Huber
Grantee:Paula Silva Felicio
Home Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Colorectal cancer is the third most common cancer worldwide and has a good prognosis when diagnosed in the early stages. Currently, the existing tests to screen colorectal cancer are: occult blood in the stool or immunohistochemical testing followed by colonoscopy in individuals with a positive result. However, despite the importance of prevention and early diagnosis are recognized the difficulties inherent in these techniques.Recent studies show that cells of precancerous lesions and adenocarcinomas of the large bowel have methylation of the promoter regions of certain genes, including the CNRIP1, FBN1, INA, SNCA, and SPG20 MAL. Thus, this research aims to assess the sensitivity and specificity of a new noninvasive method through fecal DNA markers, researching epigenetic changes in the promoter regions of these genes.For this research, should be collected feces of patients with colorectal cancer, polyps and colorectal mucosa adenomastosos normal. After collection, the protocol will be used for silica-based DNA extraction from faeces. The methylation analysis of the promoter region of genes CNRIP1 INA and must be performed by the MSP technique (Polymerase Chain Reaction Methylation Specific), which involves modification of DNA by sodium bisulfite and subsequent amplification by PCR, using primers specific for methylated and unmethylated regions. After amplification, the DNA must be subjected to electrophoretic run on 2% agarose gel stained with ethidium bromide. At the end, will be compared the possible epigenetic changes in the promoter regions of genes analyzed in the three groups studied (colorectal cancer, adenomatous polyps and colorectal mucosa normal) in order to observe different patterns of methylation among them.