Expressão imunoistoquímica das enzimas DNA metiltransferases 1, 3A e 3B em leucoplasias e carcinomas de células escamosas bucais

• Autor(a) principal: Daniel, Filipe Ivan
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional PUCRS
• Texto Completo: http://hdl.handle.net/10923/369
• topic: ODONTOLOGIA; ESTOMATOLOGIA CLÍNICA; NEOPLASIAS BUCAIS; CARCINOMA DE CÉLULAS ESCAMOSAS; IMUNOISTOQUÍMICA; DNA

Objectives: This study investigated the expression of DNA methyltransferase (DNMT) 1, 3a, and 3b enzymes in oral squamous cell carcinoma (SCC) and leukoplakia, their relationship with histopathologic graduation and dysplasia, respectively, and with clinical parameters. Study design: Immunohistochemistry using antibodies anti-DNMT1, anti-DNMT3a, and anti-DNMT3b (dilution of 1:700, Imgenex, San Diego, USA) was carried out to detect the expression of the 3 DNMTs proteins in 21 oral leukoplakias with histopathologic diagnosis of acanthosis and/or hyperkeratosis (leukoplakia without dysplasia), 16 leukoplakias with histopathologic diagnosis of epithelial dysplasia, 20 oral well differentiated SCC (grade I), 20 oral moderately differentiated SCC (grade II), and 20 oral poorly differentiated SCC (grade III). Twenty samples of non-tumor oral tissues were obtained as control. The tissues were embedded in paraffin and obtained from the pathologic archive of Division of Stomatology and Prevention of Bucomaxillofacial Cancer, São Lucas Hospital, PUCRS. Statistical analysis was done using Analysis of Variance (ANOVA), Student-Newmann-Keuls test, Pearson correlation and t test. Results: The incidence of nuclear DNMT3a immunoreactivity in oral SCC groups (39. 9%) was significantly higher than in control (22. 6%) (P<0. 05), but not when compared to oral leukoplakias groups (28. 2%). For DNMT1 and DNMT3b, there were no statistically significant difference between oral SCC groups (65% and 74. 7%), oral leukoplakia groups (68. 3% and 70. 9%) and control (65. 4% and 76. 5%). DNMT protein expression exhibited no correlation with age and no association with gender and mate. There were a significant association between the DNMT3a and alcohol use (P = 0. 01), and an inverse association between DNMT1 and smoking (P = 0. 048).Conclusions: Although there was a higher level of DNMT3a immunopositivity in SCC groups, the three studied enzymes had no predictive capacity for SCC development in patients with oral leukoplakia, and exhibited no association with their histopathological features or the clinical parameters age, gender and mate consumption. Alcohol intake was associated with a higher DNMT3a expression and smoking with a lower DNMT1 expression.