Molecular characterization of colorectal cancer patients

Introduction: Colorectal cancer has a high incidence in the world population. Differents molecular pathways are involved in the development of colorectal cancer such as chromosomal instability (CIN), microsatellite instability (MSI) and epigenetics. Objective: To perform molecular characterization in 44 individuals with sporadic colorectal cancer. Materials and methods: Mutation analisys of the APC, KRAS, TP53 y BRAF genes was carried out using Sanger sequencing techniques; microsatellite instability was performed using capillary electrophoresis with five STR genetic markers and methylation status of the MHL1 promotor gene was analysed using methylation-specific PCR. Results: The mutation frequency for APC, KRAS and TP53 genes was 18.1%, 25% and 4.5% respectively; the somatic mutations detected were located more frequently in the right colon. The frequency of MSI was 27.2% and 73.1% of the tumors had the MHL1 gene methylated. 91.6% of tumours MSI positive had the methylated MLH1 gene. The mutation profile of tumours MSS of the APC, KRAS and TP53 genes was more frequent than in the tumours MSI positive. The methylation of the MLH1 gene was the most predominant molecular alteration. Conclusions: we identified molecular alterations in the different genetic pathways in colorectal cancer patients evaluated, which are common in the carcinogenesis of the colorectal cancer. These patients shown mutational profile different from other populations. Our findings confirm the molecular heterogeneity described in the development colorectal cancer.