Isabel do Val

The presence of methylation of the p16INK4A gene and human papillomavirus in high-grade cervical squamous intraepithelial lesions.

Methylation is a chemical modification in which a methyl group (CH3) is added to the cytosine in the promoter region of the gene. It involves a very frequent epigenetic event that is found in many human cancers. Currently, there is no consensus on whether methylation of the p16 gene could be used as a biomarker in cervical intraepithelial neoplasia. The authors studied the presence of methylation of the p16INK4a gene and human papillomavirus (HPV) DNA, and a possible relationship between them in high-grade squamous intraepithelial lesions of the cervix. This case-control study analyzed 27 high-grade squamous intraepithelial lesion samples and 20 normal cytology samples. To detect p16INK4a methylation, methylation-specific polymerase chain reaction was used, and for HPV DNA detection the polymerase chain reaction was performed by using MY09/MY11 and GP5+/GP6+ consensus primers. The presence of methylation of the promoter region of the p16INK4a gene was detected in 55.6% of the samples from the case group, whereas it was detected only in 20% of the samples from the control group (P=0.005). HPV DNA was found in 66.7% of the samples from the case group, whereas only 15% from the control group (P=0.0001). The relationship between the presence of methylation of the p16INK4a gene and HPV DNA did not prove statistically significant in the case group (P=0.67) or the control group (P=0.51). In conclusion, the presence of methylation of the p16INK4a gene constituted an occurrence that was early but independent of the presence of HPV DNA.

Evaluation of DAPK gene methylation and HPV and EBV infection in cervical cells from patients with normal cytology and colposcopy

ObjectiveEvaluation of promoter methylation of the death-associated protein kinase (DAPK) gene and HPV and EBV infections in cervical cells from patients with normal cytology and colposcopy.Study designTwenty women, who had been patients at the Institute of Gynecology of the Federal University of Rio de Janeiro (UFRJ) for routine examinations and who showed normal cytology and colposcopy, were selected for this work. Cervical brushings were used for DNA extraction, and the analysis of methylation patterns of the DAPK gene was done through chemical modification with sodium bisulfite. Analysis of viral infection was done using polymerase chain reaction (PCR).ResultsOf the 20 patients studied, six (30%) presented methylation of the DAPK gene, five (25%) presented infection with EBV and three (15%) presented coinfection with HPV/EBV. Associating methylation with viral infection, we found methylated DAPK in one patient (16%) with EBV, in two patients (33%) with co-infection and in three patients (50%) with no viral infection.ConclusionsIn the present study, we verified, for the first time, the methylation pattern of the DAPK gene in cervical smears from patients with normal cytology and colposcopy. The results also showed the presence of viral infections in these patients. EBV infection, irrespective of whether associated with HPV or not, may contribute to cervical carcinogenesis as a cofactor. Methylation of the DAPK gene is associated with cell transformation, suggesting that DAPK methylation might be an important marker for the development of cervical epithelial neoplasias.