HPV16 Variants Research Articles

Genetic variability in E6 and E7 oncogenes of human papillomavirus Type 16 from Congolese cervical cancer isolates

BackgroundThe molecular epidemiological studies showed that some variants of HPV-16, distributed geographically, would present a higher risk of causing cervical cancer. This study aimed to analyze nucleotide changes of HPV-16 E6 and E7 genomic regions from infected Southwestern Congolese women.MethodsDNA of twenty HPV-16 isolates was analyzed by amplifying the E6 and E7 genes using type-specific primers PCR and direct sequencing. The sequences obtained were aligned with the HPV-16 GenBank reference sequences.ResultsThirteen (65.0%) out of 20 DNA-samples were successfully amplified. Genetic analysis revealed 18 and 4 nucleotide changes in E6 and E7 genomic regions respectively. The most frequently observed nucleotide variations were the missense C143G, G145T and C335T in E6 (100%), leading to the non-synonymous amino acid variation Q14D and H78Y. E7 genomic region was found to be highly conserved with two most common T789C and T795G (100%) silent variations. All HPV-16 variants identified belonged to the African lineage: 7 (53.8%) belonged to Af-1 lineage and 6 (46.1%) to Af-2 lineage. The missense mutation G622A (D21N) in the E7 region seems to be described for the first time in this study.ConclusionThis study reported for the first time the distribution of HPV-16 E6 and E7 genetic variants in infected women from southwest Congo. The findings confirmed almost ascendancy of the African lineage in our study population.

HPV 16 Variants in Invasive Cancers in the US Prior to HPV Vaccine Implementation

BackgroundFew studies have examined genetic variants of HPV 16 in cancers other than cervical.
 
MethodsResidual DNA extracts from samples collected from seven cancer registries as part of a pilot study to determine type‐specific HPV prevalence in US cancers prior to vaccine introduction were used. Of the 1395 histologically confirmed tumors with HPV PCR results, 1045 (74.9%) were HPV 16 positive. Valid E6 pyrosequencing allowed variant determination in 836 (80%) of the HPV 16 tumors (107 anal, 337 cervical, 30 penile, 25 vaginal, 69 vulvar and 268 oropharyngeal). Variants were designated using both geographic and group terminology for lineages. Age, sex and race/ethnicity were obtained from the registry data.
ResultsEuropean (A) lineages were the most prevalent in all cancer sites, ranging from 77.5% for penile to 95.7% for anal cancers. Within the A lineage, the E‐p and E‐T350G variants were the most common, ranging from 28‐41% and 20.5 – 33% respectively. Other non‐European variants (lineage B, C, D) were distributed in similar levels among the different cancers, with prevalence rates of less than 10% (except for AA/NA‐1 (D) lineage variants in cervical cancers‐ 12.2%). The odds ratio of European to non‐European variants was 2.8 in anal compared to cervical cancer [95% Confidence Interval 1.40 – 5.86]. Variant association with race ethnicity was: European (A) with white non‐Hispanic (NH); Eur‐AS with Asian, Pacific Islander, Af1 (B) with black NH, and AA/NA‐1 (D) with Hispanic.
ConclusionsRace/ethnicity is associated with HPV 16 variants. HPV 16 European (A) variants were predominant in cancers from all primary sites.

2014 Science National Prize "Distribution of HPV-16 variants isolates in Paraguayan women with different degree of cervical lesion"

2014 Science National Prize "Distribution of HPV-16 variants isolates in Paraguayan women with different degree of cervical lesion"

OC-0493: Head and neck cancer HPV16 variant analysis, HPV E2 variations and E2 protein disruption as radiation sensitivity biomarker

OC-0493: Head and neck cancer HPV16 variant analysis, HPV E2 variations and E2 protein disruption as radiation sensitivity biomarker

Clinical characteristics of women diagnosed with carcinoma who tested positive for cervical and anal high-risk human papillomavirus DNA and E6 RNA.

High-risk human papillomavirus (hrHPV) is an essential cause of cervical carcinoma and is also strongly related to anal cancer development. The hrHPV E6 oncoprotein plays a major role in carcinogenesis. We aimed to evaluate the frequency of hrHPV DNA and E6 oncoprotein in the anuses of women with cervical carcinoma. We analyzed 117 women with cervical cancer and 103 controls for hrHPV and the E6 oncogene. Positive test results for a cervical carcinoma included 66.7 % with hrHPV-16 and 7.7 % with hrHPV-18. One case tested positive for both HPV variants (0.9 %). The samples from the anal canal were positive for HPV-16 in 59.8 % of the cases. Simultaneous presence of HPV in the cervix and anal canal was found in 53.8 % of the cases. Regarding expression of E6 RNA, positivity for HPV-16 in the anal canal was found in 21.2 % of the cases, positivity for HPV-16 in the cervix was found in 75.0 %, and positivity for HPV-18 in the cervix was found in 1.9 %. E6 expression in both the cervix and anal canal was found in 19.2 % of the cases. In the controls, 1 % tested positive for HPV-16 and 0 % for HPV-18. Anal samples from the controls showed a hrHPV frequency of 4.9 % (only HPV16). The presence of hrHPV in the anal canal of women with cervical cancer was detected at a high frequency. We also detected E6 RNA expression in the anal canal of women with cervical cancer, suggesting that these women are at risk for anal hrHPV infection.

Human papillomavirus variants among Inuit women in northern Quebec, Canada

BackgroundInuit communities in northern Quebec have high rates of human papillomavirus (HPV) infection, cervical cancer and cervical cancer–related mortality as compared to the Canadian population. HPV types can be further classified as intratypic variants based on the extent of homology in their nucleotide sequences. There is limited information on the distribution of intratypic variants in circumpolar areas.ObjectiveOur goal was to describe the HPV intratypic variants and associated baseline characteristics.DesignWe collected cervical cell samples in 2002–2006 from 676 Inuit women between the ages of 15 and 69 years in Nunavik. DNA isolates from high-risk HPVs were sequenced to determine the intratypic variant.ResultsThere were 149 women that were positive for HPVs 16, 18, 31, 33, 35, 45, 52, 56 or 58 during follow-up. There were 5 different HPV16 variants, all of European lineage, among the 57 women positive for this type. There were 8 different variants of HPV18 present and all were of European lineage (n=21). The majority of samples of HPV31 (n=52) were of lineage B. The number of isolates and diversity of the other HPV types was low. Age was the only covariate associated with HPV16 variant category.ConclusionsThese frequencies are similar to what was seen in another circumpolar region of Canada, although there appears to be less diversity as only European variants were detected. This study shows that most variants were clustered in one lineage for each HPV type.

Genetic variations of human papillomavirus type 16: implications for cervical carcinogenesis.

Human papillomaviruses (HPVs) are the causative agent of cervical cancer, and among approximately 15 high-risk genotypes, HPV16 accounts for more than half the cases of cervical cancer worldwide. Recent progress in determining HPV genomic sequences from clinical samples has revealed a wide variety in HPV16 genome sequences, and has allowed for comprehensive classification of intratype HPV16 variants. These consist of four variant lineages containing nucleotide variations in 1.0%-10.0% of the complete viral genome sequence. Epidemiological data suggest that the non-European-Asian lineages of HPV16 entail a higher risk of progression to invasive cervical cancer than the European-Asian lineage. Deep sequencing analysis has recently demonstrated that HPV16 genome sequences are highly homogeneous in individual clinical specimens compared with those of RNA viruses. However, an extremely sensitive PCR method, differential DNA denaturation PCR, has detected hypermutations from C to T or G to A in the E2 gene and the long control region of the HPV16 genome, which suggests the involvement of cellular apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) proteins in this hypermutation. The quasispecies status of the HPV16 genome in the infected cervix may affect the development of cervical cancer and warrants further investigation.

369 Diagnosis and molecular targeting for individualized treatment of patients with pre-neoplastic lesions and locally advanced cervical cancer

Background: The natural history of HPV infection and development of cervical intraepithelial neoplasia indicate that most lesions disappear without treatment in contrast to a significant proportion of high-grade lesions that progress to invasive cancer if not treated. Persistent infection with high-risk HPV may be necessary for the development of cervical cancer. The purpose of the study was make a retrospective molecular diagnosis that include detection of HPV16 variants, polymorphism Arg72Pro of P53, expression of anti-apoptotic markers such as IGF-1R and Survivin, and hypoxic markers and glycolytic as GLUT1 and CAIX and markers of progression as hTERT in samples invasive cancer and preneoplastic lesions taken in 2002 and 1986; the results may be useful to propose an appropriate therapeutic management.

Unexpected inverse correlation between Native American ancestry and Asian American variants of HPV16 in admixed Colombian cervical cancer cases

BackgroundEuropean (E) variants of HPV 16 are evenly distributed among world regions, meanwhile Non-European variants such as European-Asian (EAs), Asian American (AA) and African (Af) are mostly confined to Eastern Asia, The Americas and African regions respectively. Several studies have shown that genetic variation of HPV 16 is associated with the risk of cervical cancer, which also seems to be dependent on the population. This relationship between ethnicity and variants have led to the suggestion that there is co-evolution of variants with humankind. Our aim was to evaluate the relationship between the individual ancestry proportion and infection with HPV 16 variants in cervical cancer. MethodsWe examined the association between ancestry and HPV 16 variants in samples of 82 cervical cancer cases from different regions of Colombia. Individual ancestry proportions (European, African and Native American) were estimated by genotyping 106 ancestry informative markers. Variants were identified by PCR amplification of the E6 gene, followed by reverse line blot hybridization (RLB) with variants specific probes. ResultsOverall European (E) and Asian American (AA) variants frequency was 66.5% and 33.5% respectively. Similar distribution was observed in cases with higher proportions of European or African ancestry. A higher Native American ancestry was significantly associated with higher frequency of E variants (median ancestry>23.6%, Age and place of birth adjusted OR: 3.55, 95% CI: 1.26–10.03, p=0.01). Even further, an inverse geographic correlation between Native American ancestry and frequency of infections with AA variants was observed (ρ=−0.825, p=0.008). Regions with higher proportion of Native American ancestry had a lower frequency of AA variants of HPV 16. ConclusionsThis study suggests replacement of AA variants by E variants of human papillomavirus 16 in cervical cancer cases with high Native American ancestry.

Prevalence of HPV and variation of HPV 16/HPV 18 E6/E7 genes in cervical cancer in women in South West China

Genetic variations of High-Risk HPV E6/E7 may be associated with the development of cervical cancer in specific geographic regions. Few data have been reported about the HPV prevalence and E6/E7 variants among cervical cancer patients in Southwest China. This study was designed to investigate the prevalence of HPV and E6/E7 variants of most prevalent HPV among cervical cancer patients in Southwest China. After genotyping, E6/E7 genes of most prevalent HR HPV samples were sequenced and analyzed. Phylogenetic trees were then constructed, followed by an analysis of the diversity of secondary structure and selection pressures. HPV 16 (73.8%) and HPV 18 (16.4%) are the most prevalent infection types among cervical cancer patients, followed by HPV 58, HPV 56 and HPV 59, which is different from the high HPV 58 infection rate of outpatients in this region. Eighteen single nucleotide changes were observed in HPV 16 E6 with 13/18 non-synonymous mutations (5 in beta sheet and 2 in alpha helix). Ten single nucleotide changes were identified among HPV 16 E7 with 3/10 non-synonymous mutations. Three single nucleotide changes were observed in HPV 18 E6 with one non-synonymous mutation, and only one synonymous mutation was identified in HPV 18 E7. HPV 16 E6-D25E, E7-N29S and E7-T846C (S95S) exhibited a prevalent linkage mutation. The phylogenetic tree demonstrates that European and Asian lineages were the main patterns. This study may help understand the intrinsic geographical relatedness and oncogenic potential of HR HPV and contributes further to research of diagnostic, therapeutic and therapeutic vaccine strategy.

Prevalence of human papillomavirus infection and phylogenetic analysis of HPV-16 E6 variants among infected women from Northern Brazil.

BackgroundThe main cause of cervical cancer in the world is high risks human papillomavirus infection (mainly represented by HPV-16 and HPV-18), that are associated to the development of malign transformation of the epithelium. HPV prevalence exhibits a wide geographical variability and HPV-16 variants have been related to an increased risk of developing cervical intraepithelial lesion. The aim of this study was to describe DNA-HPV prevalence and HPV-16 variants among a women population from Northern Brazil.MethodsOne hundred and forty three women, during routine cervical cancer screening, at Juruti Project, fulfilled an epidemiological inquiry and were screened through a molecular HPV test. HPV-16 variants were determined by sequencing the HPV-16 E6 open reading frame.ResultsForty two samples were considered HPV positive (29.4%). None of those had abnormal cytology results. HPV prevalence varied between different age groups (Z(U) = 14.62; p = <0.0001) and high-risk HPVs were more frequent among younger ages. The most prevalent type was HPV-16 (14%) and it variants were classified, predominantly, as European (87.5%).ConclusionsHPV prevalence in our population was higher than described by others and the most prevalent HPV types were high-risk HPVs. The European HPV-16 variant was the most prevalent among HPV-16 positive samples. Our study reinforces the fact that women with normal cytology and a positive molecular test for high-risk HPVs should be submitted to continuous follow up, in order to verify persistence of infection, promoting an early diagnosis of cervical cancer and/or its precursors.

Human papillomavirus type 16 long control region and E6 variants stratified by cervical disease stage

ObjectiveCertain intra-type variants of HPV16 have been shown to be associated with an increased risk of developing high grade cervical disease, but their potential association is confounded by apparent geographic and phylogenetic lineage dependency. The objective of this study was to evaluate the relationship between HPV16 sequence variants and cervical disease stage in monospecific infection samples from a single lineage (European, EUR) in England. MethodsOne hundred and twelve women singly infected with HPV16 and displaying normal and abnormal cytology grades were selected. An 1187bp fragment encompassing the entire LCR and a portion of the E6 open reading frame was sequenced to identify intra-type variants. Intra-type diversity was estimated using Shannon entropy. ResultsAlmost all samples (110/112; 98%) were assigned to the EUR lineage, one sample was classified as European-Asian (EAS) and another African (Afr1a). The mean pairwise distance of the EUR sequences in this study was low (0.29%; 95%CI 0.13–0.45%) but there were nevertheless several sites in the LCR (n=5) and E6 (n=2) that exhibited a high degree of entropy. None of these sites, however, including the T350G non-synonymous (L83V) substitution in E6, alone or in combination, were found to be associated with cervical disease stage. ConclusionsDespite using single infection samples and samples from a single variant lineage, intra-type variants of HPV16 were not differentially associated with cervical disease. Monitoring intra-lineage, site-specific variants, such as T350G, is unlikely to be of diagnostic value.

High risk HPV genotypes in Belarus

Results Of 764 PCR positive samples there were sequenced 77 and 10 DNAs on genes L1 (296 bp) and E6/E7 (620 bp) HPV-16 regions, respectively. The phylogenetic analysis of gene L1 region established that generally all samples from Belarus clustered round reference-sequences from South East Asia and Europe, only 15 and 9 samples formed independent groups with each other. p-distances between the Belarusian samples fluctuated from 0.000 to 0.024 that points as to new virus penetration to the country, and on circulation of our “old” HPV-16 types which formed independent groups of samples on a phylogenetic tree. Separately the sample 63 from Gomel settled down, it didn’t enter one of groups. Most likely, it is our “domestic” HPV-16 variant. Three viruses, two from Minsk and one from the Grodno region settled down in one group “Africa” with African reference sequences, but separately from each other that points to a different origin of a virus at these patients. Sequencing on gene of E6 and E6/E7 region also divided viruses into groups. Also as well as on L1 gene on gene E6/E7 region virus formed, generally the general groups with Asian HPV-16 variants. In too time part of isolates settled down separately and formed independent groups.

Long-Term Follow-Up of HPV16-Positive Women: Persistence of the Same Genetic Variant and Low Prevalence of Variant Co-Infections

HPV16 variants correlate with geographic origin and ethnicity. The association between infection with a specific variant and the cervical disease risk remains unclear. We studied the prevalence, persistence and association with cervical intraepithelial neoplasia (CIN) of different HPV16 variants, using cervical swabs and whole tissue sections (WTS) of biopsies from 548 women in the placebo group of a HPV16/18 vaccine trial. In HPV16-positive samples, HPV16 variants were identified by a reverse hybridization assay (RHA). Laser-capture micro-dissection (LCM) was performed for localized detection of HPV. HPV16 variants were determined in 47 women. Frequency of mixed HPV16 variant infections was lower (8.5%) than for multiple HPV genotypes (39.1%). Among 35 women having consecutive HPV16 variant-positive swabs, 32 (91.4%) had the same variant while in three (8.6%) women a change in variant(s) was observed. HPV16-positive WTS were obtained from 12 women having consecutive HPV16 variant-positive swabs. The same variant was present in WTS of 10 women, while two were negative. WTS of five women were histologically normal. A single HPV16 variant was detected in four women having CIN1-3, while additional HPV genotypes were found in three other women having CIN2 and CIN3. In the WTS of one woman with mixed genotypes, the HPV16 variant was assigned to a CIN2 lesion by LCM. HPV16 variant infections can be effectively studied in cervical swabs and tissue specimens by the HPV16 variant RHA. Multiple HPV16 variants in one woman are rare. The HPV16 genotype consistently detected in follow-up samples usually involves a persistent infection with the same variant.

Evolution and taxonomic classification of alphapapillomavirus 7 complete genomes: HPV18, HPV39, HPV45, HPV59, HPV68 and HPV70.

BackgroundThe species Alphapapillomavirus 7 (alpha-7) contains human papillomavirus genotypes that account for 15% of invasive cervical cancers and are disproportionately associated with adenocarcinoma of the cervix. Complete genome analyses enable identification and nomenclature of variant lineages and sublineages.MethodsThe URR/E6 region was sequenced to screen for novel variants of HPV18, 39, 45, 59, 68, 70, 85 and 97 from 1147 cervical samples obtained from multiple geographic regions that had previously been shown to contain an alpha-7 HPV isolate. To study viral heterogeneity, the complete 8 kb genome of 128 isolates, including 109 sequenced for this analysis, were annotated and analyzed. Viral evolution was characterized by constructing phylogenic trees using maximum-likelihood and Bayesian algorithms. Global and pairwise alignments were used to calculate total and ORF/region nucleotide differences; lineages and sublineages were assigned using an alphanumeric system. The prototype genome was assigned to the A lineage or A1 sublineage.ResultsThe genomic diversity of alpha-7 HPV types ranged from 1.1% to 6.7% nucleotide sequence differences; the extent of genome-genome pairwise intratype heterogeneity was 1.1% for HPV39, 1.3% for HPV59, 1.5% for HPV45, 1.6% for HPV70, 2.1% for HPV18, and 6.7% for HPV68. ME180 (previously a subtype of HPV68) was designated as the representative genome for HPV68 sublineage C1. Each ORF/region differed in sequence diversity, from most variable to least variable: noncoding region 1 (NCR1) / noncoding region 2 (NCR2) > upstream regulatory region (URR) > E6 / E7 > E2 / L2 > E1 / L1.ConclusionsThese data provide estimates of the maximum viral genomic heterogeneity of alpha-7 HPV type variants. The proposed taxonomic system facilitates the comparison of variants across epidemiological and molecular studies. Sequence diversity, geographic distribution and phylogenetic topology of this clinically important group of HPVs suggest an independent evolutionary history for each type.

Analysis of mutations in the E6 oncogene of human papillomavirus 16 in cervical cancer isolates from Moroccan women

BackgroundWorldwide, cervical cancer is the second most common cancer in women. High-risk human papillomavirus (HPV) play a crucial role in the etiology of cervical cancer and the most prevalent genotype is HPV16. HPV 16 intratypic variants have been reported to differ in their prevalence, biological and biochemical properties. The present study was designed to analyze and identify HPV type 16 E6 variants among patients with cervical cancer in Morocco.MethodsA total of 103 HPV16 positive samples were isolated from 129 cervical cancer cases, and variant status was subsequently determined by DNA sequencing of the E6 gene.ResultsIsolates from patients were grouped into the European (E), African (Af) and North-American (NA1) phylogenetic clusters with a high prevalence of E lineage (58.3%). The Af and NA1 variants were detected in 31.1% and 11.6% of the HPV16 positive specimens, respectively, whereas, only 3% of cases were prototype E350T. No European-Asian (EA), Asian (As) or Asian-American (AA) variants were observed in our HPV16-positive specimens. At the amino acid level, the most prevalent non-synonymous variants were L83V (T350G), H78Y (C335T), E113D (A442C), Q14D (C143G/G145T) and R10I (G132T), and were observed respectively in 65%, 41.8%, 38.8%, 30.1% and 23.3% of total samples.Moreover, HPV16 European variants were mostly identified in younger women at early clinical diagnosis stages. Whereas, HPV16 Af variants were most likely associated with cervical cancer development in older women with pronounced aggressiveness.ConclusionThis study suggests a predominance of E lineage strains among Moroccan HPV 16 isolates and raises the possibility that HPV16 variants have a preferential role in progression to malignancy and could be associated with the more aggressive nature of cervical cancer.

Next generation sequencing for human papillomavirus genotyping

BackgroundHuman papillomavirus (HPV) genotyping using next generation sequencing (NGS) could be useful to study the HPV variant-specific epidemiology, including monitoring for possible emergence of new HPV variants after introduction of HPV vaccination programs. ObjectivesWe wished to design and validate a method for rapid HPV detection, typing and sequencing in clinical samples. Study designPlasmids of 15 different HPV types were mixed and serially diluted in human DNA in concentrations ranging from 1 to 100 copies per sample, amplified using the HPV general PCR primer pair PGMY and sequenced using 454 technology. Sixty cervical samples were tested both with the NGS-based method and with a comparison method based on genotyping using type-specific probes bound to fluorescent beads (Luminex). Thirty-three clinical samples were repeat tested using NGS to evaluate reproducibility. ResultsThe NGS-based method correctly identified all 15 mixed HPV types when present in 100 copies/sample and 13/15 types when present in 10 copies/sample. For 36/60 cervical samples genotyping results using NGS and Luminex were identical. For 12/60 samples the NGS method was more sensitive than the Luminex test and most of the remaining discrepancies could be explained by the different type coverage of the assays. Reproducibility testing found complete or partial concordance in 30/33 samples. ConclusionsNGS provides a sensitive and accurate method for genotyping of HPV. The fact that also the amplimer sequence is obtained could be important for studying the epidemiology of viral variants and monitoring of HPV vaccination.

Nucleotide polymorphisms of the human papillomavirus 16 E1 gene

The E1 ORF is one of the most conserved regions in the human papillomavirus (HPV) genome. The complete E1 gene of the HPV16 genome was amplified with four overlapping primer sets in 16 high-grade (CIN II, III) and 13 low-grade cervical (CIN I) intraepithelial neoplasias as well as in one cervical cancer case. Sequence analysis of the E6 and E7 genes was also carried out in the same cervical samples in order to confirm the association between nucleotide sequence variations in the HPV16 E1 ORF and HPV16 variant lineages. Analysis of the E1 ORF revealed 27 nucleotide changes, and these changes were correlated with those found in HPV16 Asian American and African type II variants. Of these nucleotide variations, A1668G, G2073A, T2169C, T2189C, A2453T, C2454T, A2587T and G2650A were identified only in high-grade dysplasia cases. A phylogenetic tree of the E1 ORF and nucleotide sequence analysis of the E1, E6 and E7 genes revealed that intratypic nucleotide sequence polymorphisms located in the E1 ORF can be used to identify the major phylogenetic branch to which a HPV16 genome belongs. Moreover, amplification of the E1 ORF revealed a disruption between nucleotides 878 and 1523 in five high- and two low-grade cervical cases, indicating that integration of HPV DNA occurs at an early stage of viral infection.

Association of tumor necrosis factor-alpha promoter variants with risk of HPV-associated oral squamous cell carcinoma

BackgroundTumor necrosis factor alpha (TNF-α) plays an important role in inflammation, immunity, and defense against infection and clearance of human papillomavirus (HPV). Thus, genetic variants may modulate individual susceptibility to HPV-associated oral squamous cell carcinoma (OSCC).MethodsIn this study we genotyped four common single nucleotide polymorphisms (SNPs) in the TNF-α promoter [ −308G > A(rs1800629), -857C > T (rs1799724), -863C > A (rs1800630), and -1031T > C (rs1799964)] and determined HPV16 serology in 325 OSCC cases and 335 matched controls and tumor HPV status in 176 squamous cell carcinomas of the oropharynx (SCCOP) patients. Univariate and multivariable logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).ResultsWe found that HPV16 seropositivity alone was associated with an increased risk of OSCC (OR, 3.1; 95% CI, 2.1–4.6), and such risk of HPV16-associated OSCC was modified by each SNP. Patients with both HPV16 seropositivity and variant genotypes for each SNP had the highest risk when using patients with HPV16 seronegativity and a wild-type genotype as a comparison group. Moreover, similar results were observed for the combined risk genotypes of four variants and all such significant associations were more pronounced in several subgroups, particularly in SCCOP patients and never smokers. Notably, the combined risk genotypes of four variants were also significantly associated with tumor HPV-positive SCCOP.ConclusionTaken together, these results suggest that TNF-α SNPs may individually or, more likely, jointly affect individual susceptibility to HPV16-associated OSCC, particularly SCCOP and never smokers. Validation of our findings is warranted.

Regulation of p14ARF expression by HPV‐18 E6 variants

A common causative agent for uterine cervical cancer is the human papillomavirus type 18 (HPV-18) which has three phylogenic variants: Asian-Amerindian, European, and African. Each variant shows significant molecular differences in the E6 gene. E6 oncoprotein is a negative regulator of tumor suppressor protein p53, hence, this oncoprotein indirectly regulates the expression of tumor-suppressor p14(ARF) . p14(ARF) and p16(INK4A) genes are overexpressed in--and have been proposed as markers for--HPV-related cervical cancer. In order to dissect the role of E6 on the regulation of p14(ARF) expression, separating it from that of other intervening factors, transfection of E6 variants to MCF-7 cells was performed, assessing cDNA transcript levels by RT-PCR, whereas p14(ARF) and p53 expression were evaluated by immunocytochemistry and Western blot. E6 transfected cells differentially expressed transcripts of two molecular forms: E6 and E6*. The ratio of these two forms varied with the transfected E6 variant. With the Asian-Amerindian variant, the ratio was E6 > E6*, whereas with the European and the African the ratio was E6* > E6. As expected with the E6* construct, E6* transcripts were solely observed. In addition, when E6 > E6* and p53 expression was low, p14(ARF) was high and when E6* > E6 and p53 expression was high, p14(ARF) was low. In conclusion, each E6 variant distinctively affects p53 levels and consequently p14(ARF) expression, finding that could be related with the differences in oncogenic effect of infection with the diverse high-risk HPV variants.