Análise da imunoexpressão das proteínas de reparo do DNA mismatch repair (MMR) na carcinogênese do vermelhão do lábio

• Autor(a) principal: Barragán, Yamyle Claudia Velasquez
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/59799
• topic: Lábio; Neoplasias bucais; Proteínas MutS; Proteínas MutL

Squamous cell carcinoma (SCC) of the lip usually appears after actinic cheilitis (AC), the main precursor lesion. Overexposure to type A and B ultraviolet sun rays causes DNA mutations that lead to alterations in DNA repair proteins, especially those of the Mismatch Repair (MMR) complex. This family of proteins is related to post-replicational DNA repair, correcting nitrogenous bases incorrectly incorporated into the genome through its two main heterodimers (MutSα: MSH2 and MSH6; MutLα: PMS2 and MLH1). In this context, this project aimed to analyze the immunoexpression of these MMR complex proteins in the carcinogenesis of lip vermilion. An analytical cross-sectional study was carried out with biopsies from the Ceará Cancer Institute (ICC), in which healthy lip epithelia from pelveglossectomies (15 cases), QA (30 cases) and CEC of the lip (45 cases) were selected. were subjected to immunohistochemistry for MSH2, MSH6, PMS2, MLH1 and ki-67. Clinical-prognostic variables such as sex, age, place of birth, origin, entry into the service (public or private), occupation, history of smoking or alcohol consumption, TNM staging, recurrence and therapeutic protocol were also evaluated. The groups were compared using the Mann-Whitney or Kruskal-Wallis/Dunn tests between study groups and between clinical and prognostic data. SCC and QA showed a significant increase in immunoexpression for MutSα (p<0.001), MSH6 (p<0.001) and MLH1 (p=0.040) and in the MSH2/MSH6 ratio (p<0.001). The MSH2/MSH6 ratio in QA was greater than the PMS2/MLH1 ratio (p=0.028). AK with high-risk dysplasia (p=0.024) and SCC with vascular invasion (p=0.035) had lower immunoexpression for MSH6. T3/T4 tumors had higher MutSα (p=0.028) and MutLα (p=0.014) ratios and, in patients with nodal metastasis, the MutLα ratio was significantly higher than the MSH2/MSH6 ratio (p=0.046). This study demonstrated that the process of lip carcinogenesis (CEC) is related to alterations in the immunoexpression of MUTSα and MUTLα proteins.