Tarik Gheit

The biological properties of E6 and E7 oncoproteins from human papillomaviruses

More than 100 different human papillomavirus (HPV) types have been isolated so far, and they can be sub-grouped in cutaneous or mucosal according to their ability to infect the skin or the mucosa of the genital or upper-respiratory tracts. A sub-group of human mucosal HPVs, referred to as high-risk HPV types, is responsible for approximately 5% of all human cancers, which represents one-third of all the tumours induced by viruses. Epidemiological and biological studies have shown that HPV16 is the most oncogenic type within the high-risk group. Emerging lines of evidence suggest that, in addition to the high-risk mucosal HPV types, certain cutaneous HPVs are involved in skin cancer. HPV-associated cancers are intimately linked to HPV persistence and the accumulation of chromosomal rearrangements. The products of the early genes, E6 and E7, of the high-risk mucosal HPV types play a key role in both events. Indeed, these proteins have developed a number of strategies to evade host immuno-surveillance allowing viral persistence, and to alter cell cycle and apoptosis control, facilitating the accumulation of DNA damage/mutations. Often, the two oncoproteins target the same cellular pathways with different mechanisms, showing a strong synergism in promoting cellular transformation and neutralizing the immune response. Here, we review most of the findings on the biological properties and molecular mechanisms of the oncoproteins E6 and E7 from mucosal and cutaneous HPV types.

Low human papillomavirus prevalence in head and neck cancer: results from two large case–control studies in high-incidence regions

BACKGROUND Recent studies support an important role for human papillomavirus (HPV) in a subgroup of head and neck squamous cell carcinomas (HNSCC). We have evaluated the HPV deoxyribonucleic acid (DNA) prevalence as well as the association between serological response to HPV infection and HNSCC in two distinct populations from Central Europe (CE) and Latin America (LA). METHODS Cases (n = 2214) and controls (n = 3319) were recruited from 1998 to 2003, using a similar protocol including questionnaire and blood sample collection. Tumour DNA from 196 fresh tissue biopsies was analysed for multiple HPV types followed by an HPV type-specific polymerase chain reaction (PCR) protocol towards the E7 gene from HPV 16. Using multiplex serology, serum samples were analysed for antibodies to 17 HPV types. Statistical analysis included the estimation of adjusted odds ratios (ORs) and the respective 95% confidence intervals (CIs). RESULTS HPV16 E7 DNA prevalence among cases was 3.1% (6/196), including 4.4% in the oropharynx (3/68), 3.8% in the hypopharynx/larynx (3/78) and 0% among 50 cases of oral cavity carcinomas. Positivity for both HPV16 E6 and E7 antibodies was associated with a very high risk of oropharyngeal cancer (OR = 179, 95% CI 35.8-899) and hypopharyngeal/laryngeal cancer (OR = 14.9, 95% CI 2.92-76.1). CONCLUSIONS A very low prevalence of HPV DNA and serum antibodies was observed among cases in both CE and LA. The proportion of head and neck cancer caused by HPV may vary substantially between different geographical regions and studies that are designed to evaluate the impact of HPV vaccination on HNSCC need to consider this heterogeneity.

Development of a Sensitive and Specific Assay Combining Multiplex PCR and DNA Microarray Primer Extension To Detect High-Risk Mucosal Human Papillomavirus Types

ABSTRACT The importance of assays for the detection and typing of human papillomaviruses (HPVs) in clinical and epidemiological studies has been well demonstrated. Several accurate methods for HPV detection and typing have been developed. However, comparative studies showed that several assays have different sensitivities for the detection of specific HPV types, particularly in the case of multiple infections. Here, we describe a novel one-shot method for the detection and typing of 19 mucosal high-risk (HR) HPV types (types 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 70, 73, and 82). This assay combines two different techniques: multiplex PCR with HPV type-specific primers for amplification of viral DNA and array primer extension (APEX) for typing. This novel method has been validated with artificial mixtures of HPV DNAs and clinical samples that were already analyzed for the presence of mucosal HPV types by a different consensus PCR method, i.e., GP5+/GP6+. Our data showed a very good agreement between the results from the multiplex PCR/APEX assay and those from the GP5+/GP6+ PCR (overall rates of HPV positivity, 63.0 and 60.9%, respectively). Whereas the GP5+/GP6+ PCR was slightly more sensitive for the detection of HPV type 16 (HPV-16), multiplex PCR-APEX found a higher number of infections with HPV-33, HPV-53, and multiple HPV types. These favorable features and the high-throughput potential make our present novel assay ideal for large-scale clinical and epidemiological studies aimed at determining the spectrum of mucosal HR HPV types in cervical specimens.

Abundance of Multiple High-Risk Human Papillomavirus (HPV) Infections Found in Cervical Cells Analyzed by Use of an Ultrasensitive HPV Genotyping Assay

ABSTRACT PCR methods enable the detection of a large variety of human papillomavirus (HPV) genotypes that infect the anogenital tract. However, PCR with consensus primers, general primers, and, to a lesser extent, broad-spectrum primers may underrepresent the true prevalence of HPV, especially the true prevalence of multiple infections. We compared the rate of HPV positivity determined by a broad-spectrum PCR with primers BSGP5+ and BSGP6+ (BS-PCR) coupled to an established bead-based multiplex HPV genotyping (MPG) assay with the rate of HPV positivity determined by a multiplex PCR with type-specific primers (TS-PCR) coupled to a newly developed MPG assay for 735 selected cervical scraping samples. While the primers used for the BS-PCR are located within the L1 region of the HPV genome, the primers used for the TS-PCR target the E7 gene. The overall rates of positivity for the 19 HPV types included in both assays were 60.9% and 72.2% by the BS-PCR and the TS-PCR, respectively, and the two assays found multiple infections in 34.8% and 58.0% of the specimens, respectively. Both HPV detection assays allowed the semiquantitative detection of HPV types and identified the same dominant HPV type in 66.6% of the multiple infections. In conclusion, the TS-PCR-MPG assay significantly increased the rate of detection of HPV DNA and the number of infections with multiple HPV types detected and demonstrated that the prevalence of low-copy-number HPV infections in the anogenital tract may be strongly underestimated by conventional HPV amplification methods, especially in cases of multiple infections. As a consequence, PCR-TS-MPG appears to be highly suited for analysis of the significance of multiple infections in the development of cervical cancer and for the study the natural history and the latency of HPV.

E6 and E7 from Beta Hpv38 Cooperate with Ultraviolet Light in the Development of Actinic Keratosis-Like Lesions and Squamous Cell Carcinoma in Mice

Cutaneous beta human papillomavirus (HPV) types appear to be involved in the development of non-melanoma skin cancer (NMSC); however, it is not entirely clear whether they play a direct role. We have previously shown that E6 and E7 oncoproteins from the beta HPV type 38 display transforming activities in several experimental models. To evaluate the possible contribution of HPV38 in a proliferative tissue compartment during carcinogenesis, we generated a new transgenic mouse model (Tg) where HPV38 E6 and E7 are expressed in the undifferentiated basal layer of epithelia under the control of the Keratin 14 (K14) promoter. Viral oncogene expression led to increased cellular proliferation in the epidermis of the Tg animals in comparison to the wild-type littermates. Although no spontaneous formation of tumours was observed during the lifespan of the K14 HPV38 E6/E7-Tg mice, they were highly susceptible to 7,12-dimethylbenz(a)anthracene (DMBA)/12-0-tetradecanoylphorbol-13-acetate (TPA) two-stage chemical carcinogenesis. In addition, when animals were exposed to ultraviolet light (UV) irradiation, we observed that accumulation of p21WAF1 and cell-cycle arrest were significantly alleviated in the skin of Tg mice as compared to wild-type controls. Most importantly, chronic UV irradiation of Tg mice induced the development of actinic keratosis-like lesions, which are considered in humans as precursors of squamous cell carcinomas (SCC), and subsequently of SCC in a significant proportion of the animals. In contrast, wild-type animals subjected to identical treatments did not develop any type of skin lesions. Thus, the oncoproteins E6 and E7 from beta HPV38 significantly contribute to SCC development in the skin rendering keratinocytes more susceptible to UV-induced carcinogenesis.

Human Papillomavirus Infections and Upper Aero-Digestive Tract Cancers: The ARCAGE Study

BACKGROUND Human papillomavirus (HPV) is causally implicated in a subset of cancers of the upper aero-digestive tract (UADT). METHODS Associations between type-specific HPV antibodies were examined among 1496 UADT cancer case subjects and 1425 control subjects by estimating odds ratios (ORs) in logistic regression analyses adjusted for potential confounders. The agreement between serology and tumor markers of HPV infection, including presence of HPV DNA and p16 expression, were examined in a subset of tumors. RESULTS HPV16 L1 seropositivity was associated with increased risk of oral cavity and oropharyngeal cancer (OR = 1.94, 95% confidence interval [CI] = 1.03 to 3.65; OR = 8.60, 95% CI = 5.21 to 14.20, respectively). HPV16 E6 antibodies were present in 30.2% of oropharyngeal case subjects and only 0.8% of control subjects (OR = 132.0, 95% CI = 65.29 to 266.86). Combined seropositivity to HPV16 E6 and E7 was rare (n = 1 of 1425 control subjects). An agreement of 67% was observed between HPV16 E6 serology and the corresponding presence of an HPV-related cancer: four of six HPV DNA-positive/p16-overexpressing tumors were HPV16 E6 antibody positive. An HPV16 independent association was observed for HPV18 and oropharyngeal cancer (OR = 8.14, 95% CI = 2.21 to 29.99 for HPV18 E6 seropositivity) and HPV6 and laryngeal cancer (OR = 3.25, 95% CI = 1.46 to 7.24 for HPV6 E7 seropositivity). CONCLUSIONS These results confirm an important role for HPV16 infection in oropharyngeal cancer. HPV16 E6 antibodies are strongly associated with HPV16-related oropharyngeal cancers. Continuing efforts are needed to consider both HPV serology and p16 staining as biomarkers relevant to the etiology and natural history of HPV16-related oropharyngeal tumors. These results also support a marginal role for HPV18 in oropharyngeal cancer and HPV6 in laryngeal cancer.

Human Papillomavirus Type 16 Genetic Variants: Phylogeny and Classification Based on E6 and LCR

ABSTRACT Naturally occurring genetic variants of human papillomavirus type 16 (HPV16) are common and have previously been classified into 4 major lineages; European-Asian (EAS), including the sublineages European (EUR) and Asian (As), African 1 (AFR1), African 2 (AFR2), and North-American/Asian-American (NA/AA). We aimed to improve the classification of HPV16 variant lineages by using a large resource of HPV16-positive cervical samples collected from geographically diverse populations in studies on HPV and/or cervical cancer undertaken by the International Agency for Research on Cancer. In total, we sequenced the entire E6 genes and long control regions (LCRs) of 953 HPV16 isolates from 27 different countries worldwide. Phylogenetic analyses confirmed previously described variant lineages and subclassifications. We characterized two new sublineages within each of the lineages AFR1 and AFR2 that are robustly classified using E6 and/or the LCR. We could differentiate previously identified AA1, AA2, and NA sublineages, although they could not be distinguished by E6 alone, requiring the LCR for correct phylogenetic classification. We thus provide a classification system for HPV16 genomes based on 13 and 32 phylogenetically distinguishing positions in E6 and the LCR, respectively, that distinguish nine HPV16 variant sublineages (EUR, As, AFR1a, AFR1b, AFR2a, AFR2b, NA, AA1, and AA2). Ninety-seven percent of all 953 samples fitted this classification perfectly. Other positions were frequently polymorphic within one or more lineages but did not define phylogenetic subgroups. Such a standardized classification of HPV16 variants is important for future epidemiological and biological studies of the carcinogenic potential of HPV16 variant lineages.

Development of a sensitive and specific multiplex PCR method combined with DNA microarray primer extension to detect beta-papillomavirus types

ABSTRACT Emerging lines of evidence indicate that the cutaneous human papillomavirus (HPV) types that belong to the genus Betapapillomavirus (beta HPV) are involved in the development of nonmelanoma skin cancer. Unlike the situation for mucosal HPV types, highly sensitive and reliable methods to identify characterized cutaneous HPV types in a single assay are limited. Here, we describe a novel one-shot method for the detection of all characterized beta HPV types, namely, HPV type 5 (HPV5), 8, 9, 12, 14, 15, 17, 19, 20, 21, 22, 23, 24, 25, 36, 37, 38, 47, 49, 75, 76, 80, 92, 93, and 96. This assay combines two different techniques: multiplex PCR using HPV type-specific primers for amplification of each E7 gene and array primer extension (APEX) for typing. This method has been validated using clinical samples which were analyzed simultaneously for the presence of cutaneous HPV types by two additional methods, i.e., the FAP59/64 PCR protocol and a commercially available PCR-reverse hybridization assay (PM-PCR RHA). Our data show good agreement between the results obtained with the multiplex PCR/APEX assay and the PM-PCR RHA method (overall HPV positivity of 92.2% for multiplex PCR/APEX assay versus 90.6% with the PM-PCR RHA) (kappa value, 50; 95% confidence interval, 13 to 88). In addition, the multiplex PCR/APEX assay showed higher sensitivity than the PM-PCR RHA did. This favorable feature and the high-throughput potential make this assay ideal for large-scale clinical and epidemiological studies aimed at determining the spectrum of cutaneous types in skin cancer.

Immunogenicity and HPV infection after one, two, and three doses of quadrivalent HPV vaccine in girls in India: a multicentre prospective cohort study

Summary Background An increase in worldwide HPV vaccination could be facilitated if fewer than three doses of vaccine are as effective as three doses. We originally aimed to compare the immunogenicity and frequency of persistent infection and cervical precancerous lesions caused by vaccine-targeted HPV after vaccination with two doses of quadrivalent vaccine on days 1 and 180 or later, with three doses on days 1, 60, and 180 or later, in a cluster-randomised trial. Suspension of the recruitment and vaccination due to events unrelated to our study meant that some enrolled girls could not be vaccinated and some vaccinated girls received fewer than the planned number of vaccinations by default. As a result, we re-analysed our data as an observational cohort study. Methods Our study was designed to be done in nine locations (188 clusters) in India. Participants were unmarried girls aged 10–18 years vaccinated in four cohorts: girls who received three doses of vaccine on days 1, 60, and 180 or later, two doses on days 1 and 180 or later, two doses on days 1 and 60 by default, and one dose by default. The primary outcomes were immunogenicity in terms of L1 genotype-specific binding antibody titres, neutralising antibody titres, and antibody avidity after vaccination for the vaccine-targeted HPV types 16, 18, 6, and 11 and incident and persistent infections with these HPVs. Analysis was per actual number of vaccine doses received. This study is registered with ISRCTN, number ISRCTN98283094; and with ClinicalTrials.gov, number NCT00923702. Findings Vaccination of eligible girls was initiated on Sept 1, 2009, and continued until April 8, 2010. Of 21 258 eligible girls identified at 188 clusters, 17 729 girls were recruited from 178 clusters before suspension. 4348 (25%) girls received three doses, 4979 (28%) received two doses on days 1 and 180 or later, 3452 (19%) received two doses at days 1 and 60, and 4950 (28%) received one dose. Immune response in the two-dose HPV vaccine group was non-inferior to the three-dose group (median fluorescence intensity ratio for HPV 16 1·12 [95% CI 1·02–1·23] and for HPV 18 1·04 [0·92–1·19]) at 7 months, but was inferior in the two-dose default (0·33 [0·29–0·38] for HPV 16 and 0·51 [0·43–0·59] for HPV 18) and one-dose default (0·09 [0·08–0·11] for HPV 16 and 0·12 [0·10–0·14] for HPV 18) groups at 18 months. The geometric mean avidity indices after fewer than three doses by design or default were non-inferior to those after three doses of vaccine. Fewer than three doses by design and default induced detectable concentrations of neutralising antibodies to all four vaccine-targeted HPV types, but at much lower concentration after one dose. Cervical samples from 2649 participants were tested and the frequency of incident HPV 16, 18, 6, and 11 infections was similar irrespective of the number of vaccine doses received. The testing of at least two samples from 838 participants showed that there was no persistent HPV 16 or 18 infections in any study group at a median follow-up of 4·7 years (IQR 4·2–5·1). Interpretation Despite the limitations imposed by the suspension of the HPV vaccination, our findings lend support to the WHO recommendation of two doses, at least 6 months apart, for routine vaccination of young girls. The short-term protection afforded by one dose of HPV vaccine against persistent infection with HPV 16, 18, 6, and 11 is similar to that afforded by two or three doses of vaccine and merits further assessment. Funding Bill & Melinda Gates Foundation.

Biological activity of probable/possible high‐risk human papillomavirus types in cervical cancer

Judging the carcinogenicity of human papillomavirus (HPV) types rarely found in cervical cancer (CxCa) is hindered by lack of studies of their biological activity in cancer tissues. To asses transcriptional activity of HPV types, we have developed ultra‐short amplimer, splice‐site specific, E6*I mRNA RT‐PCR assays for 12 high‐risk (HR)‐HPV (IARC Group 1) and eight probable/possible high‐risk (pHR)‐HPV types (IARC Group 2A/B carcinogens). Previously unreported E6*I splice sites of the six pHR‐HPV types 26, 53, 67, 70, 73 and 82 were identified by cloning and sequencing. We analyzed 97 formalin‐fixed paraffin‐embedded (FFPE) Mongolian CxCa biopsies for presence of HPV DNA by two sensitive genotyping assays, for E6*I transcripts of all HR‐/pHR‐HPV types identified and for expression of HPV surrogate markers p16INK4a, pRb and p53. E6*I of at least one HR‐/pHR‐HPV was expressed in 94 (98%) of cancer tissues including seven with pHR‐HPV types 26, 66, 70 or 82 as single transcribed types. Fifty‐eight of E6*I mRNA transcribing cases were analyzable by immunohistochemistry and displayed p16INK4a overexpression in 57 (98%), pRb downregulation in 56 (97%) and p53 downregulation in 36 (62%) tissues. The newly developed E6*I mRNA RT‐PCR assays appeared to be highly sensitive method to analyze HPV transcription in FFPE materials. Our finding of viral oncogene transcription of pHR‐HPV types 26, 66, 70 and 82 in cervical tumors, in the absence of any other transcriptionally active HR‐type and with p16INK4a overexpression and pRb downregulation, may support a reassessment of the carcinogenicity classification of these pHR‐HPV types.