Interaction of host and viral risk factors for development of cervical carcinoma in situ

The human papillomavirus 16 European-T350G E6 variant can immortalize but not transform keratinocytes in the absence of E7

Human papillomavirus type 16 is commonly implicated in HPV-related cancers. However, only a small number of infected individuals progress to this stage. Epidemiological evidence demonstrated that oncogenic risk is population-specific and variations within the viral oncogene, E6, have been suggested to play a role in these findings. Of focus in this study is the European-T350G variant, which is characterized by an L>V amino acid substitution at residue 83 of the prototype E6 protein. To elucidate the functional effects of this polymorphism, we followed keratinocytes transduced with E-T350G E6 for over 60 passages and compared them to keratinocytes transduced, in parallel, with prototype or Asian-American (Q14H/L83V/H78Y) E6. We found that although E-T350G E6 immortalized transduced keratinocytes in the absence of E7, these cells were not fully transformed. We also found that E-T350G down-regulated E-cadherin compared to the other variants, providing a possible link between its population-based oncogenicity and host genetic variations.

Lineages of oncogenic human papillomavirus types other than type 16 and 18 and risk for cervical intraepithelial neoplasia

BACKGROUND

Data on clinical outcomes of infection with variants of oncogenic human papillomavirus (HPV) types other than HPV16 and HPV18 are rare. We investigated intratypic variations in non-HPV16/18 oncogenic types and their corresponding relationships with cervical intraepithelial neoplasia grades 2-3 (CIN2/3).

METHODS

Study subjects were women who were positive for one or more of 11 non-HPV16/18 oncogenic types. Subjects were followed every six months for two years for detection of HPV and cervical lesions. Variant lineages were defined by sequencing the 3' part of the long control region and the entire E6/E7 region of HPV genome. Lineage-associated risk of CIN2/3 was assessed using logistic regression with generalized estimating equations.

RESULTS

A total of 4591 type-specific HPV infections among 2667 women were included in the analysis. The increase in risk of CIN2/3 was statistically significant for women with HPV31 A or B compared with C variants, HPV33 A1 compared with B variants, HPV45 A3 or B2 compared with B1 variants, HPV56 B compared with A2 variants, and HPV58 A1 or A3 compared with C variants. For these five types, the adjusted odds ratio associated with CIN2/3 was 2.0 (95% confidence interval [CI] = 1.5 to 2.6) for infections with single-type high-risk (HR) variants, 1.7 (95% CI = 1.0 to 2.7) for infections with two or more types but only one HR variant, and 5.3 (95% CI = 3.1 to 8.4) for infections with HR variants of two or more types as compared with those with single-type non-HR variants. The likelihood of CIN2/3 was similar for women with HPV16 infection and for those with HPV58 A1 variant infection.

CONCLUSIONS

These findings suggest that for a given HPV type, intratypic nucleotide changes may alter phenotypic traits that affect the probability of neoplasia.

Markers of vulnerability for cervical cancer in HIV-infected women

This study identifies the dimensions and markers of vulnerability among women infected with HIV regarding the development of cervical cancer. A total of 76 HIV-infected women cared for in Fortaleza, CE, Brazil from October 2007 to June 2008 participated in the study. Semi-structured interviews were used to collect socio-demographic, clinical, and sexual data, as well as situations related to health care follow-up and the prevention of cervical cancer. Identified situations were grouped according to the dimensions and markers of vulnerability. HIV-infected women experience different situations linked to individual, programmatic and social dimensions that leave them vulnerable to the development of cervical cancer. The conclusion is that this population is vulnerable to cervical cancer and specific preventive actions are necessary to supply information associated with early detection, improve knowledge, encourage self-care, and improve the quality of health services directed to this population.

E6 molecular variants of human papillomavirus (HPV) type 16: an updated and unified criterion for clustering and nomenclature

Reports on taxonomic identification of E6/HPV 16 variants, don't have a worldwide, updated and unified criterion for clustering and nomenclature. Our aim was to update the existing criterion and propose a new one for clustering and nomenclature for E6/HPV 16 molecular variants based on the descriptive and comparative analyses of nucleotide sequences. A systematic search of the publications between 1991 and 2010 was carried out in PUBMED and manually. 240 E6/HPV 16 variants were identified. 157 were classified as European (E), 24 as Asian (As), 14 as Asian American (AA), 11 as North American 1 (NA 1), 19 as African 1 (Af 1) and 15 as African 2 (Af 2). Three classes were determined for the E, 3 each for the As, Af 2 and AA branches, 4 classes for the NA 1 and 6 for the Af 1 branch. This study reports our results and proposes an updated criterion for clustering and nomenclature that will be useful for E6 variant identification.

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.

Interaction between polymorphisms of the human leukocyte antigen and HPV-16 variants on the risk of invasive cervical cancer

Background

Persistent infection with oncogenic types of human papillomavirus (HPV) is the major risk factor for invasive cervical cancer (ICC), and non-European variants of HPV-16 are associated with an increased risk of persistence and ICC. HLA class II polymorphisms are also associated with genetic susceptibility to ICC. Our aim is to verify if these associations are influenced by HPV-16 variability.

Methods

We characterized HPV-16 variants by PCR in 107 ICC cases, which were typed for HLA-DQA1, DRB1 and DQB1 genes and compared to 257 controls. We measured the magnitude of associations by logistic regression analysis.

Results

European (E), Asian-American (AA) and African (Af) variants were identified. Here we show that inverse association between DQB1*05 (adjusted odds ratio [OR] = 0.66; 95% confidence interval [CI]: 0.39–1.12]) and HPV-16 positive ICC in our previous report was mostly attributable to AA variant carriers (OR = 0.27; 95%CI: 0.10–0.75). We observed similar proportions of HLA DRB1*1302 carriers in E-P positive cases and controls, but interestingly, this allele was not found in AA cases (p = 0.03, Fisher exact test). A positive association with DRB1*15 was observed in both groups of women harboring either E (OR = 2.99; 95% CI: 1.13–7.86) or AA variants (OR = 2.34; 95% CI: 1.00–5.46). There was an inverse association between DRB1*04 and ICC among women with HPV-16 carrying the 350T [83L] single nucleotide polymorphism in the E6 gene (OR = 0.27; 95% CI: 0.08–0.96). An inverse association between DQB1*05 and cases carrying 350G (83V) variants was also found (OR = 0.37; 95% CI: 0.15–0.89).

Conclusion

Our results suggest that the association between HLA polymorphism and risk of ICC might be influenced by the distribution of HPV-16 variants.

Risk for high-grade cervical intraepithelial neoplasia associated with variants of human papillomavirus types 16 and 18

BACKGROUND

Although the variant lineages of human papillomavirus (HPV) types 16 and 18 are well established, their individual associations with high-grade cervical intraepithelial neoplasia (CIN) have not been extensively evaluated.

METHODS

Study subjects were women participating in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study who were positive for HPV16 or HPV18 at enrollment. These women were followed every 6 months for 2 years. Viral isolates from enrollment samples were characterized by DNA sequencing and classified as variant lineages.

RESULTS

Over a 2-year study period, CIN3 was histologically diagnosed in 291 of the 779 HPV16-positive women and 47 of the 275 HPV18-positive women. Among women without CIN2-3 at enrollment, the risk of subsequent CIN3 was 2.7-fold greater for those with HPV16 African-2 [95% confidence interval (95% CI), 1.0-7.0] and 3.1-fold greater for those with HPV16 Asian American (95% CI, 1.6-6.0), compared with European variants. Relative to infection with HPV18 African variants, the risk associating subsequent CIN3 was 3.8 (95% CI, 0.9-17.2) for infection with HPV18 European variants and 4.8 (95% CI, 1.0-23.6) for infection with HPV18 Asian American variants. Similar associations were observed when the 2-year prevalence of CIN3 was used as the end point. Further, for those with HPV16 European variants, the 2-year prevalence of CIN3 was higher in White women than in African American women (P = 0.01); this trend was reversed for those with HPV16 African-1 variants (P = 0.22). A similar pattern was present for infections with HPV18 European versus African variants.

CONCLUSIONS

The lineages of HPV16 and HPV18 variants are associated with differing risks for high-grade CIN.

HLA-DQB1 polymorphisms and risk for cervical cancer: A case-control study in a southern Chinese population

OBJECTIVES AND METHODS

HLA II DQB1 polymorphisms have been shown to associate with cervical cancer risk, but results varied among different populations. In this study, the HLA DQB1 alleles among 221 southern Chinese women with cervical intraepithelial neoplasia grade III (CIN III)/invasive cervical carcinoma (ICC) were compared to 191 controls.

RESULTS

The frequency of DQB1*03 was significantly lower among ICC overall as compared to controls (65.4% vs. 79.1%, odds ratio [95% confidence interval]: 0.50 [0.28-0.88], corrected p-value: 0.04). The protective association of DQB1*03 remained significant for human papillomavirus (HPV) 16-positive ICC, but not for HPV16-negative cases. This is in contrast to studies on European populations where DQB1*03 was associated with an increased risk for ICC. In the current study, 70.1% of the HPV16 isolates were Asian variants, and 28.0% were European variants. However, no significant association between HPV16 variant and DQB1*03 distribution was observed. HPV52 and HPV58 were found respectively in 16.3% and 10.0% of CIN III/ICC, which were higher compared to that of Europe and North America. Further analyses revealed a positive risk association between DQB1*06 and HPV58-positive CIN III/ICC (3.68 [1.37-9.92], corrected p-value: 0.012).

CONCLUSION

The host genetics and the distribution of HPV types/variants may account for the observed differences among southern Chinese and other populations.

Expression of a novel alternatively spliced variant of NADP(H)-dependent retinol dehydrogenase/reductase with deletion of exon 3 in cervical squamous carcinoma

NADP(H)-dependent retinol dehydrogenase/reductase (NRDR) plays an important role in maintaining the homeostasis of retinoid. Aberrations in retinoid metabolism are considered as early events in carcinogenesis. We identified a novel alternatively spliced variant, NRDRB1, in HeLa cell and human cervical squamous carcinoma tissues, which is characterized by a complete deletion of exon 3. The latter resulted in changes in subcellular localization of NRDRB1 when compared with the peroxisomal localization of NRDR. To clarify the clinical significance of NRDRB1, we investigated its mRNA and protein expressions in normal cervical and cervical squamous carcinoma tissues, using RT-PCR, quantitative real-time PCR, Gateway expressing system, immunoprecipitation, immunoblotting, MALDI-TOF mass spectrometry and immunohistochemistry. We detected NRDRB1 mRNA in 14 of 26 (53.9%) cervical cancer tissues, but in none of the 12 normal cervical tissues. NRDRB1 protein was expressed in NRDRB1 mRNA-positive cases. While the full-length NRDR mRNA was observed in both normal and neoplastic cervical tissues, its protein was only expressed in normal cervical epithelium. The results presented here provide evidence that metabolic disturbances of retinal and retinoic acid, due to abnormal splicing and functional disorder of NRDR, may be involved in cervical tumorigenesis.

HPV16 E6 variants and HLA class II polymorphism among Chinese women with cervical cancer

Infection with human papillomavirus type 16 (HPV16) confers a high risk for the development of cervical cancer. Variants of this virus may interact differentially with host genetic factors, possibly affecting the disease pathogenesis. This study was designed to investigate the association between HPV16 E6 variants and human leukocyte antigen (HLA) polymorphism within a Chinese population. Peripheral blood from HPV16 positive Chinese women with cervical carcinoma, who had previously been tested for HPV16 E6 variants, was used for HLA class II typing. It was found that there was a significant positive association between DQB1*060101 allele and HPV16 As variant-positive cervical cancers (OR, 4.47; Pc=0.0018). A negative relationship was found between DRB1*150101-DQB1*0602 haplotype and decreased risk for HPV16 As variant-positive cervical cancers (OR=0.31; P=0.037). Similar tendency was observed for the haplotype DRB1*070101-DQB1*0201 with HPV16 As variant-positive cervical cancers (OR=0.16, P=0.024). Additionally, as for the HPV16 E6 prototype-positive cervical cancers, a significant positive association was found in DQB1*060101 allele (OR=5.95; P=0.002; Pc=0.036), and similar trends were observed for DQB1*030201 (OR=10.87, P<0.0001; Pc=0.0018), and DPB1*1301(OR=7.40, P=0.002; Pc=0.04). It was found that there was no significant association between DRB1-DQB1 haplotype and HPV16 prototype-positive cervical cancers. These data indicate that host genetic factors, such as HLA polymorphism, may determine the potential oncogenicity of the HPV16 E6 variant. The results suggest that a specific match between E6 variant proteins and HLA class II alleles may contribute to HPV16-related cervical carcinogenesis in a certain Chinese population.