Sequence variation in the E2-binding domain of HPV16 and biological function evaluation in Tunisian cervical cancers

Genetic variability of the HPV16 early genes and LCR. Present and future perspectives

Human papillomavirus 16 (HPV16) infection is the aetiologic factor for the development of cervical dysplasia and is regarded as highly carcinogen, because it is implicated in more than 50% of cervical cancer cases, worldwide. The tumourigenic potential of HPV16 has triggered the extensive sequence analysis of viral genome in order to identify nucleotide variations and amino acid substitutions that influence viral oncogenicity and subsequently the initiation and progression of cervical cancer. Nowadays, specific mutations of HPV16 DNA have been associated with an increased risk of high-grade squamous intraepithelial lesions and invasive cervical cancer (ICC) development, including E6: Q14H, H78Y, L83V, Ε7: N29S, S63F, E2: H35Q, P219S, T310K, E5: I65V, whereas highly conserved regions of viral DNA have been extensively characterised. In addition, numerous novel HPV16 mutations are observed among the studied populations from various geographic regions, hence advocating that different HPV16 strains seem to emerge with different tumourigenic capacities. The present review focuses on the variability of the early genes and the long control region, emphasising on the association of specific mutations with the development of severe dysplasia. Finally, it evaluates whether specific regions of HPV16 DNA are able to serve as valuable biomarkers for cervical cancer risk.

The association of human papillomavirus type 16 E2 variations with cervical cancer in a Han Chinese population

Human papillomavirus type 16 (HPV16) is considered to be the primary pathogen related to cervical cancer. The HPV16 E2 protein plays an important role in tumourigenicity of cervical carcinoma. In the current study, we enrolled 121 HPV16-positive cervical cancer patients in the case group and 130 HPV16-positive asymptomatic individuals in the control group, and we investigated the association between HPV16 E2 gene variations and cervical cancer. The HPV16 E2 DNA was amplified and sequenced. We identified two HPV variants (EUR and As) in the control group; the As variant was predominant (68.5%), followed by the EUR variant (31.5%). In the case group, three HPV variants (EUR, As and AA) were observed; the As variant was predominant (72.7%), followed by the EUR variant (22.3%) and the AA variant (5.0%). Our results showed a significant difference in the distribution of the HPV16 variants between the case and control groups (P < 0.05). Moreover, in the HPV16 E2 gene variation analysis, the distribution of sixteen variations was significantly different between the case and control groups (P < 0.05), and all of these variations were present in the AA variant. In the subgroup analysis, the frequency of the T3575G (S274A) variation in the EUR variant was significantly different between the case and control groups (P = 0.029); however, there was no significant difference in the frequency of the variations in the As variant between the case and control groups. Our findings in the current study could provide a better understanding of the relationship between HPV16 variants, E2 gene variations and cervical cancer.