Potential biomarker of human papillomavirus 16 L1 methylation for prediction of anal intraepithelial neoplasia in men who have sex with men (MSM)

Abstract

Quantitative measurement of human papillomavirus (HPV) 16 early promoter and L1 genes methylation were analyzed in anal cells collected from men who have sex with men (MSM) to determine the potential biomarker for screening of HPV related anal cancer. The methylation patterns of the HPV16 genes including early promoter (CpG 31, 37, 43, 52 and 58) and L1 gene (CpG 5600, 5606, 5609, 5615, 7136 and 7145) were analyzed in 178 anal samples with histology diagnosed as normal, anal intraepithelial neoplasia (AIN) 1, AIN2 and AIN3 by pyrosequencing assay. Low methylation levels of early promoter (20-60%) in early promoter was found 1.5% (1/67) and 5% (2/40) in AIN1 and AIN2-3 samples, respectively. Interestingly, slightly increased L1 gene methylation level (>20-60%) especially at HPV16 5L1 regions CpGs 5600 and 5609 from normal to AIN3 were demonstrated. Moreover, negative correlation between high HPV16 L1 gene methylation at CpGs 5600, 5609, 5615 and 7145 and low percentage of CD4+ was found in AIN3 HIV positive cases. When compared methylation status of AIN2-3 to those of the normal/AIN1 lesion, the results indicated potential of using HPV16 L1 gene methylation as a biomarker for HPV related cancer screening.