Aim:To evaluate the methylation of carbonic anhydrase IX (CAIX) promoter and CAIX gene expression in oral cancer and smokers. Methods: The collected oral cells samples were classified in to five groups, with each group containing 15 samples. Group 1, oral squamous cell carcinoma (OSCC); group 2, normal contralateral mucosa (NCM) of patients from group OSCC; group 3, normal mucosa in chronic smokers (CS); group 4, normal mucosa in ex-smokers (ES) in cessation for one year; and group 5, normal mucosa in never-smokers (NS). Samples were evaluated through methylation-specific polymerase chain reaction (PCR) and quantitative PCR. Results: The CAIX gene was methylated in only 20% of samples from group OSCC; in groups NCM, CS, ES and NS, all cases were unmethylated. CAIX expression of group OSCC was lower than in NS (P = 0.005). There was no statistically significant difference between CAIX expression in other groups, NCM and NS (P = 0.285), CS and NS (P = 0.530) and ES and NS (P = 0.068). Conclusion: CAIX methylation is higher in oral cancer and its expression is reduced in the same cases whose methylation is present. However, the methylation profile and the expression of this gene are not modified in chronic smokers and ex-smokers after one year of smoke cessation.
Key words:Carcinoma, squamous cell, methylation, carbonic anhydrase IX, gene expression, tobacco
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