Alterações do gene TP53 na mucosa esofágica de pacientes com carcinoma epidermóide do esôfago

Abstract

Esophageal cancer is a tumor with a higher incidence in males, and it is highly fatal. Epidemiological data points out to consumption of tobacco and alcohol and the exposition to polycyclic aromatic hydrocarbon are the main risk factors for the development of this cancer. The TP53 gene is responsible for growth control and cell division, and fifty percent of all human tumors presents somatic mutation in this gene. The objective was to verify the prevalence of mutations in the exons 5, 6, 7, 8 and 9 of TP53 gene in esophageal biopsies of patients with esophageal squamous cell carcinoma diagnosed at Hospital Universitario de Santa Maria. We extracted the DNA from 49 esophageal biopsies through salting out technique. The analysis of TP53 gene was performed by amplification of the exons 5, 6, 7, 8 e 9 by the PCR technique. Then, the samples were submitted to sequencing analysis. Forty-nine samples proved to be viable for amplification. Nine cases showed at least one mutation in any of the 5 exons. Among these 9 cases, we found 4 (44.4%) mutations in exon 5, 2 (22.2) in exon 7 and 3 (33.3%) in exon 8. We did not find mutations in exons 6 and 9. Overall the samples presented 17 somatic mutations with point mutations in 8 of them, most G:C> A:T. Only one case presented insertion type mutation. The prevalence of mutations in TP53 gene in the present study was 18.36%. The pattern of mutations found was heterogeneous, and most potentially attributable transversions to environmental carcinogens.