HPV16E1 downregulation altered the cell characteristics involved in cervical cancer development

The primary causes of cervical cancer are human papillomavirus type 16 (HPV16) and/or other high-risk (Hr -) HPV infections. Hr-HPVE5, E6, and E7 have been identified as oncoproteins that play roles in the development of cancer. However, other HPV proteins, especially E1, may also be involved in cancer development. In this study, the role of HPV16E1 in cervical carcinogenesis was examined by siRNA knockdown experiments using SiHa cells as a model. The results showed that HPV16E1 regulated P-FOXO3a and HPV16E7 expression. Various cell functions associated with the hallmarks of cancer, including cell viability, colony formation, invasion, and anchorage-independent cell growth, were altered when HPV16E1 was downregulated. However, no effect on cell migration and apoptosis properties was found. Moreover, HPV16E1 downregulation resulted in an increase in cisplatin susceptibility. In conclusion, this is the first demonstration that HPV16E1 might be regarded as a possible novel oncoprotein involved in several processes related to oncogenesis.

Human papillomavirus 16 L1 gene methylation as a potential biomarker for predicting anal intraepithelial neoplasia in men who have sex with men (MSM)

The human papillomavirus (HPV) 16 early promoter and L1 gene methylation were quantitatively measured using pyrosequencing assay in anal cells collected from men who have sex with men (MSM) to determine potential biomarkers for HPV-related anal cancer. The methylation patterns of HPV16 genes, including the early promoter (CpG 31, 37, 43, 52, and 58) and L1 genes (CpG 5600, 5606, 5609, 5615, 7136, and 7145), were analyzed in 178 anal samples. The samples were diagnosed as normal, anal intraepithelial neoplasia (AIN) 1, AIN2, and AIN3. Low methylation levels of the early promoter (< 10%) and L1 genes (< 20%) were found in all detected normal anal cells. In comparison, medium to high methylation (≥ 20–60%) in the early promoter was found in 1.5% (1/67) and 5% (2/40) of AIN1 and AIN2-3 samples, respectively. Interestingly, slightly increased L1 gene methylation levels (≥ 20–60%), especially at the HPV16 5’L1 regions CpGs 5600 and 5609, were demonstrated in AIN2-3 specimen. Moreover, a negative correlation between high HPV16 L1 gene methylation at CpGs 5600, 5609, 5615, and 7145 and a percentual CD4 count was found in AIN3 HIV positive cases. When comparing the methylation status of AIN2-3 to that of normal/AIN1 lesions, the results indicated the potential of using HPV16 L1 gene methylation as a biomarker for HPV-related cancer screening.