Polymorphism in the E6 gene of human papillomavirus type 16 in the cervical tissues of Korean women

Genetic diversity of E6, E7 and the long control region in human papillomavirus type 16 variants in Beijing, China

Background

High-risk human papillomavirus type 16 (HPV16) is a risk factor for cervical cancer. The progression from initial infection to cervical cancer has been linked to properties of the viral sequences. However, the distribution of HPV16 variants among Chinese women has not been extensively addressed and the role of HPV16 variants in the risk of cervical carcinogenesis remains poorly understood.

Methods

HPV16 positive cervical exfoliated cell samples were collected from 249 women living in Beijing, China. PCR products from two fragments of E6-E7 and LCR of HPV16 in these samples were sequenced and analyzed.

Results

Lineage A was found in the subjects, including A1, A2, A3 and A4 sublineages. Based on the HPV16 reference sequences, 26 nucleotide mutations of A4 sublineage and 39 nucleotide mutations of A1-3 sublineages were found in the E6, E7 and LCR of HPV16 isolates. Point mutations T843C, A7287C and A7872G of A4 sublineage were significantly associated with high-grade cervical lesions. The high-frequency sites in HPV16 LCR located at regions that can bind to multiple transcription factors.

Conclusions

This study contributes to the identification of unique variants in the E6, E7 and LCR of HPV16 isolates infected in Chinese women. Mutations of T843C, A7287C and A7872G in A4 sublineages were significantly associated with high-grade cervical lesions, suggesting that mutations in the E7 and LCR region have potential effects on viral replication and progression of cervical cancer.

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Lineage A is the predominant HPV16 variant in Chinese women.

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Based on the HPV16 prototype, 25 nucleotide mutations in E6 and E7 were found and 41 nucleotide mutations in LCR were found.

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The mutations of C843T, A7287C and A7872G were significantly correlated with the cervical lesions.

Human papillomavirus as a driver of head and neck cancers

The human papillomavirus (HPV) family includes more than 170 different types of virus that infect stratified epithelium. High-risk HPV is well established as the primary cause of cervical cancer, but in recent years, a clear role for this virus in other malignancies is also emerging. Indeed, HPV plays a pathogenic role in a subset of head and neck cancers-mostly cancers of the oropharynx-with distinct epidemiological, clinical and molecular characteristics compared with head and neck cancers not caused by HPV. This review summarises our current understanding of HPV in these cancers, specifically detailing HPV infection in head and neck cancers within different racial/ethnic subpopulations, and the differences in various aspects of these diseases between women and men. Finally, we provide an outlook for this disease, in terms of clinical management, and consider the issues of 'diagnostic biomarkers' and targeted therapies.

Distribution of HPV 16 E6 gene variants in screening women and its associations with cervical lesions progression

The aim of this study is to investigate distribution of human papillomavirus (HPV) 16 variants in screening healthy women and the potential association between HPV 16 variants and progression of cervical lesions. For this study a total of 2000 healthy women in Tianjin urban area and 212 patients who were HPV 16 positive and underwent colposcopy were analyzed for HPV 16 variants by pyrosequencing. The results show that the HPV 16 was the most prevalent genotype in Tianjin healthy women and five HPV 16 variant types were detected. The HPV 16 variants were determined by sequencing parital E6 region and the detected variants were European prototype E-T350 (E-p), E-G350, E-C109 G, Asian (As) and Asian-American (AA), among which the E-p variant was the most prevalent (82.76%) followed by As variant. Interestingly, in patients with suspected cervical lesions the most prevalent variant was As variant (54.9%) by increasing significance with severity of cervical diseases (OR 4.337; 95% CI 1.248-15.067; P = 0.021), and followed by HPV 16 E-p variant while E-G350 variant only appeared in HSIL and cervical cancer. Our results show that HPV 16 E-p variant was more prevalent than As in Tianjin healthy screening women while As variant was the most frequently type in HSIL and cervical cancer. It is suggested that the mutation of HPV 16 Asian variants, comparing with HPV 16 E-p variants, might contribute to the transformation from HPV 16 persistent infection to cervical cancer.

HPV16 genetic variation and the development of cervical cancer worldwide

BACKGROUND

Factors that favour a small proportion of HPV16 infections to progress to cancer are still poorly understood, but several studies have implicated a role of HPV16 genetic variation.

METHODS

To evaluate the association between HPV16 genetic variants and cervical cancer risk, we designed a multicentre case-control study based on HPV16-positive cervical samples (1121 cervical cancer cases and 400 controls) from the International Agency for Research on Cancer biobank. By sequencing the E6 gene, HPV16 isolates were classified into variant lineages and the European (EUR)-lineage isolates were subclassified by the common polymorphism T350G.

RESULTS

Incidence of variant lineages differed between cases and controls in Europe/Central Asia (P=0.006, driven by an underrepresentation of African lineages in cases), and South/Central America (P=0.056, driven by an overrepresentation of Asian American/North American lineages in cases). EUR-350G isolates were significantly underrepresented in cervical cancer in East Asia (odds ratio (OR)=0.02 vs EUR-350T; 95% confidence interval (CI)=0.00-0.37) and Europe/Central Asia (OR=0.42; 95% CI=0.27-0.64), whereas the opposite was true in South/Central America (OR=4.69; 95% CI=2.07-10.66).

CONCLUSION

We observed that the distribution of HPV16 variants worldwide, and their relative risks for cervical cancer appear to be population-dependent.

Human papillomavirus type 16 e6 gene variations in young Chinese women with cervical squamous cell carcinoma

Human papillomavirus (HPV) 16 E6 gene mutation is considered an important genetic change in cervical lesion progression. To explore the possible association of specific HPV16 E6 sequence variations with the development of invasive cervical squamous cell carcinoma (SCC) in young women, we examined the distribution of HPV16 E6 variants in a Chinese cervical SCC population and analyzed the difference between younger patients (≤35 years, n = 50) and older ones (>35ys, n = 71). Human papillomavirus type 16 E6 DNA was amplified by polymerase chain reaction and sequenced by Sanger fluorescent dye dideoxy-termination method. Analysis revealed that the most frequently found variation in this Chinese population was the EV (As) lineage (65.45%). In addition, the EV (As) lineage seems more common and uniform in younger patients than other lineages, and it may be associated with early age at diagnosis of cervical SCC in young women.

HPV variants and HLA polymorphisms: the role of variability on the risk of cervical cancer

Human papillomavirus (HPV) infection is linked to the development of cervical cancer, and several cofactors contribute to the risk of disease. Research on the intratypic variability of HPVs has defined variants that are associated with persistent infections and are potentially more oncogenic, translating to a higher risk of malignant disease. The genetic variability of the host also plays a role in the risk of cervical cancer, especially genes controlling the immune response, such as HLA class I and II. These highly polymorphic genes are important risk determinants of HPV persistence and disease progression. The interaction between host and viral factors is complex and needs to be further investigated, paving the way to better define the patients at the highest risk of developing malignant diseases linked to HPV infection.