Physical and methylation status of human papillomavirus 16 in asymptomatic cervical infections changes with malignant transformation

Identification of novel genomic hotspots and tumor-relevant genes via comprehensive analysis of HPV integration in Chinese patients of cervical cancer

Cervical cancer accounts for 10-15% of cancer-related mortality among women globally. Infection with high-risk human papillomavirus (HPV) types constitutes a significant etiological factor in the development of cervical carcinoma. The integration of HPV DNA into the host genome is considered a pivotal event in cervical carcinogenesis. Nevertheless, the precise mechanisms underlying HPV integration and its role in promoting cancer progression remain inadequately understood. Therefore, this study aims to identify potential common denominators at HPV DNA integration sites and to analyze the adjacent cellular sequences. We conducted whole-genome sequencing on 13 primary cervical cancer samples, employing the chromosomal coordinates of 537 breakpoints to assess the statistical overrepresentation of integration sites in relation to various chromatin features. Our analysis, which encompassed all chromosomes, identified several integration hotspots within the human genome, notably at 14q32.2, 10p15, and 2q37. Additionally, our findings indicated a preferential integration of HPV DNA into intragenic and gene-dense regions of human chromosomes. A substantial number of host cellular genes impacted by the integration sites were associated with cancer, including IKZF2, IL26, AHRR, and PDCD6. Furthermore, the cellular genes targeted by integration were enriched in tumor-related terms and pathways, as demonstrated by gene ontology and KEGG analysis. In conclusion, these findings enhance our understanding of HPV integration sites and provide deeper insights into the molecular mechanisms underlying the pathogenesis of cervical carcinoma.

Identification of transcriptionally-active human papillomavirus integrants through nanopore sequencing reveals viable targets for gene therapy against cervical cancer

Integration of the human papillomavirus (HPV) genome into the cellular genome is a key event that leads to constitutive expression of viral oncoprotein E6/E7 and drives the progression of cervical cancer. However, HPV integration patterns differ on a case-by-case basis among related malignancies. Next-generation sequencing technologies still face challenges for interrogating HPV integration sites. In this study, utilizing Nanopore long-read sequencing, we identified 452 and 108 potential integration sites from the cervical cancer cell lines (CaSki and HeLa) and five tissue samples, respectively. Based on long Nanopore chimeric reads, we were able to analyze the methylation status of the HPV long control region (LCR), which controls oncogene E6/E7 expression, and to identify transcriptionally-active integrants among the numerous integrants. As a proof of concept, we identified an active HPV integrant in between RUNX2 and CLIC5 on chromosome 6 in the CaSki cell line, which was supported by ATAC-seq, H3K27Ac ChIP-seq, and RNA-seq analysis. Knockout of the active HPV integrant, by the CRISPR/Cas9 system, dramatically crippled cell proliferation and induced cell senescence. In conclusion, identifying transcriptionally-active HPV integrants with Nanopore sequencing can provide viable targets for gene therapy against HPV-associated cancers.

Differential association of hedgehog pathway in development of cervical carcinoma and its chemo-tolerance

Cervical carcinoma (CACX) is still a dreadful threat to women in developing countries. Available conventional chemo-radiation therapies are not sufficient to restrict the disease recurrence. To unravel the mechanism of the disease recurrence, alteration of hedgehog self-renewal pathway was evaluated during development of CACX and in chemo-tolerance of the tumor. We have analyzed the alterations (expression/methylation/deletion) of some key regulatory genes (HHIP/SUFU/SHH/ SMO/GLI1) of hedgehog self-renewal pathway in cervical lesions at different clinical stages and compared with different datasets, followed by their clinico-pathological correlations. The changes in expression/methylation of the genes were then evaluated in two CACX cell lines (SiHa/HeLa) after treatment with chemotherapeutic drug cisplatin at different concentrations. Down regulation (mRNA/protein) of the antagonists HHIP and SUFU due to promoter methylation and/or deletion along with upregulation (protein) of agonists SHH, SMO and GLI1 was seen in early invasive lesions and subsequent clinical stages. Reduced protein expression of HHIP and SUFU showed significant association with high/intermediate expression of agonists SHH, SMO, GLI1 in the tumors and also poor prognosis of the patients. It was evident that cisplatin could restrict the growth of HeLa and SiHa cells through significant upregulation of antagonists HHIP and SUFU due to their promoter hypomethylation and down regulation of SHH in a concentration dependent manner without any significant changes in expression of SMO and GLI1, leading to the tumor cells in a dormant state. Thus, interplay of the agonists and antagonists has important role in activation of hedgehog pathway during development of CACX, whereas inactivation of the pathway due to upregulation of the antagonists is an important phenomenon in chemo-tolerance of the tumor. This suggests importance of epigenetic modification in chemo-resistance of CACX.

Extrachromosomal Amplification of Human Papillomavirus Episomes Is a Mechanism of Cervical Carcinogenesis

SIGNIFICANCE

Multimers of the HPV genome are generated in cervical tumors replicating as extrachromosomal episomes, which is associated with deletion and rearrangement of the HPV genome and provides a mechanism for oncogenesis without integration.

The use of human papillomavirus DNA methylation in cervical intraepithelial neoplasia: A systematic review and meta-analysis

BACKGROUND

Methylation of viral DNA has been proposed as a novel biomarker for triage of human papillomavirus (HPV) positive women at screening. This systematic review and meta-analysis aims to assess how methylation levels change with disease severity and to determine diagnostic test accuracy (DTA) in detecting high-grade cervical intra-epithelial neoplasia (CIN).

METHODS

We performed searches in MEDLINE, EMBASE and CENTRAL from inception to October 2019. Studies were eligible if they explored HPV methylation levels in HPV positive women. Data were extracted in duplicate and requested from authors where necessary. Random-effects models and a bivariate mixed-effects binary regression model were applied to determine pooled effect estimates.

FINDINGS

44 studies with 8819 high-risk HPV positive women were eligible. The pooled estimates for positive methylation rate in HPV16 L1 gene were higher for high-grade CIN (≥CIN2/high-grade squamous intra-epithelial lesion (HSIL) (95% confidence interval (95%CI:72·7% (47·8-92·2))) vs. low-grade CIN (≤CIN1/low-grade squamous intra-epithelial lesion (LSIL) (44·4% (95%CI:16·0-74·1))). Pooled difference in mean methylation level was significantly higher in ≥CIN2/HSIL vs. ≤CIN1/LSIL for HPV16 L1 (11·3% (95%CI:6·5-16·1)). Pooled odds ratio of HPV16 L1 methylation was 5·5 (95%CI:3·5-8·5) for ≥CIN2/HSIL vs. ≤CIN1/LSIL (p < 0·0001). HPV16 L1/L2 genes performed best in predicting CIN2 or worse (pooled sensitivity 77% (95%CI:63-87), specificity 64% (95%CI:55-71), area under the curve (0·73 (95%CI:0·69-0·77)).

INTERPRETATION

Higher HPV methylation is associated with increased disease severity, whilst HPV16 L1/L2 genes demonstrated high diagnostic accuracy to detect high-grade CIN in HPV16 positive women. Direct clinical use is limited by the need for a multi-genotype and standardised assays. Next-generation multiplex HPV sequencing assays are under development and allow potential for rapid, automated and low-cost methylation testing.

FUNDING

NIHR, Genesis Research Trust, Imperial Healthcare Charity, Wellcome Trust NIHR Imperial BRC, European Union's Horizon 2020.

Quantification of HPV16 E6/E7 mRNA Spliced Isoforms Viral Load as a Novel Diagnostic Tool for Improving Cervical Cancer Screening

High-risk human papillomaviruses (HPVs) have been identified as the main contributors to cervical cancer. Despite various diagnostic tools available, including the predominant Papanicolaou test (Pap test), technical limitations affect the efficiency of cervical cancer screening. The aim of this study was to evaluate the diagnostic performance of spliced HPV16 E6/E7 mRNA viral loads (VL) for grade 2 or higher cervical intraepithelial neoplasia diagnosis. A new dedicated (quantitative reverse transcription polymerase chain reaction) qRT-PCR assay was developed, allowing selective quantification of several HPV16 E6/E7 mRNA: Full length (FL) with or without all or selected spliced forms (total E6/E7 mRNA corresponding to SP + E6^E7 mRNA (T), + spliced E6/E7 mRNA containing intact E7 ORF (SP), and E6/E7 mRNA containing disrupted E6 and E7 ORFs calculated by the following subtraction T-SP (E6^E7)). Twenty HPV16 DNA and mRNA positive uterine cervical smears representative of all cytological and histological stages of severity were tested. We have shown that all E6/E7 mRNA isoforms expression levels were significantly increased in high grade cervical lesions. Statistical analysis demonstrated that the SP-E6/E7 VL assay exhibited: (i) The best diagnostic performance for identification of both cervical intraepithelial neoplasia (CIN)2+ (90% (56–100) sensitivity and specificity) and CIN3+ (100% (72–100) sensitivity and 79% (49–95) specificity) lesions; (ii) a greater sensitivity compared to the Pap test for CIN2+ lesions detection (80% (44–97)); (iii) a predictive value of the histological grade of cervical lesions in 67% of atypical squamous cells of unknown significance (ASC-US) and 100% of low-grade (LSIL) patients. Overall, these results highlight the value of SP-E6/E7 mRNA VL as an innovative tool for improving cervical cancer screening.

Elevated HPV16 E1 Expression Is Associated with Cervical Cancer Progression

OBJECTIVES

The primary replication protein, HPV E1, has been shown to play a role in mitigating host defence and disrupting normal cell cycle processes, leading to the development of cancer. This study investigated the expression profile of HPV16 E1 in various stages of cervical cancer development and the factors that control E1 expression.

METHODS

One hundred and twenty-four HPV16-positive cervical samples ranging from normal to CIN 1, CIN 2/3, and SCC lesions were studied. E1 mRNA expression was determined by ddPCR. Methylation of promoters p97 and p670 was quantified by pyrosequencing, while PCR, qPCR, and sequencing were used to determine the physical state and variations of the HPV16 E1 genome.

RESULTS

Increased E1 mRNA expression related to disease progression (normal 0.18, CIN 1 0.41, CIN 2/3 0.65, and SCC 0.79) was demonstrated with a significant positive correlation (r = 0.661, p = 0.019). No association between physical state and E1 expression was found. Methylation of p97 and p670 promoters showed significant elevation in SCC compared to normal samples. Only 4.2% showed genomic variations of HPV16 E1 63-bp duplication.

CONCLUSION

E1 may play a role in cancer development. The detection of E1 mRNA and promoter methylation may be useful as cancer prognostic markers.

Physical state and copy numbers of HPV16 in oral asymptomatic infections that persisted or cleared during the 6-year follow-up

Persistent human papillomavirus (HPV) infection is a key event in HPV-induced carcinogenesis. As part of the prospective Finnish Family HPV Study, we analysed the physical state and viral copy numbers of HPV16 in asymptomatic oral infections that either persisted or cleared during the 6-year follow-up. The persister group comprised 14 women and 7 men with 51 and 21 HPV16-positive brush samples. The clearance group included 41 women and 13 men, with 64 and 24 samples, respectively. Physical state and viral DNA load were assessed by using quantitative PCR for HPV16 E2 and E6 genes. E2/E6 ratio was calculated and HPV16 was classified as episomal, mixed or integrated with values of 0.93-1.08, <0.93 and 0, respectively. In both genders, the physical state of HPV16 was significantly different between the cases and controls (P<0.001). HPV16 was episomal in all men and 66 % (27/41) of women who cleared their infection. HPV16 was mixed and/or integrated in71 % and 57 %of the women and men persisters, respectively. The mean HPV16 copy number per 50 ng genomic DNA was nearly 5.5-fold higher in the women than in the men clearance group (P=0.011). Only in men, HPV16 copy numbers were higher in persisters than in the clearance group (P=0.039). To conclude, in both genders, persistent oral HPV16 infections were associated with the mixed or integrated form of HPV16, while in the clearance groups, episomal HPV16 predominated. This indicates that HPV16 integration is a common event even in asymptomatic oral infections, which might predispose the infected subjects to progressive disease.

Increased methylation of human papillomavirus type 16 DNA is associated with the severity of cervical lesions in infected females from northeast China

Hypermethylation of the cytosine-phosphate-guanine (CpG) sites located at the 3'-major capsid protein L1 (3'L1) and the long control region (LCR) of the human papillomavirus (HPV) genome may be associated with the progression of cervical cancer (CC). However, the methylation status of the LCR of HPV type 16 DNA remains to be elucidated in an infected Chinese population. The aim of the present study was to investigate the association between methylation of the HPV 16 L1 gene and LCR, and the severity of cervical lesions in infected female patients. Therefore, bisulfite modification, polymerase chain reaction amplification and sequencing were used to analyze 122 HPV 16-positive clinical cervical swabs obtained from patients in northeastern China. The proportion of methylated samples at each of the 7 CpG sites within the 3'-L1/5'-LCR and 5 CpG sites within the promoter region was significantly increased in patients with CC, compared with that observed in high-grade squamous intraepithelial lesions (HSIL) and normal tissue/low-grade intraepithelial lesions (LSIL) (χ2 test, P<0.01). The mean methylation frequencies of the CpG sites 7,089 and 7,143 exhibited an area under the curve value of 0.822 [95% confidence interval (CI)=0.733-0.911] for distinguishing CC from other lesions, 0.787 (95% CI=0.700-0.874) for distinguishing normal/LSIL from HSIL and CC, and 0.763 (95% CI=0.652-0.874) for distinguishing CC from HSIL. These results suggest that the methylation of CpG sites within the HPV 16 3'-L1 and LCR region is correlated with the severity of cervical lesions. Quantification of HPV DNA methylation in the L1 gene and promoter region appears to provide a promising novel marker for distinguishing between normal tissue/LSIL, HSIL and CC in a Chinese population.

Study of association and molecular analysis of human papillomavirus in breast cancer of Indian patients: Clinical and prognostic implication

OBJECTIVES

Human papillomavirus (HPV) causes tumors primarily Cervical cancer. Recently, inconsistent reports came up in Breast cancer (BC) too. In India, despite treatment 70,218 BC patients die each year. So, we explored the association of HPV, if any, with BC prognosis in Indian pre-therapeutic (PT) and Neo-adjuvant chemotherapy (NACT) patients with subsequent analysis of HPV profile.

METHODS

HPV prevalence was checked and analysis of physical status, copy number, genome variation, promoter methylation and expression (mRNA and protein) of the prevalent subtype was done.

RESULTS

High prevalence of HPV was observed in both PT (64.0%) and NACT (71.0%) cases with significant association with younger (20-45 yrs) PT patients. Interestingly, HPV infection was significantly increased from adjacent normal breast (9.5%, 2/21), fibro adenomas (30%, 3/10) to tumors (64.8%, 203/313) samples. In both PT and NACT cases, HPV16 was the most prevalent subtype (69.0%) followed by HPV18 and HPV33. Survival analysis illustrated hrHPV infected PT patients had worst prognosis. So, detailed analysis of HPV16 profile was done which showed Europian-G350 as the most frequent HPV16 variant along with high rate of integration. Moreover, low copy number and hyper-methylation of P97 early promoter were concordant with low HPV16 E6 and E7 mRNA and protein expression. Notably, four novel variations (KT020838, KT020840, KT020841 and KT020839) in the LCR region and two (KT020836 and KT020837) in the E6 region were identified for the first time along with two novel E6^E7*I (KU199314) and E6^E7*II (KU199315) fusion transcript variants.

CONCLUSION

Thus, significant association of hrHPV with prognosis of Indian BC patients led to additional investigation of HPV16 profile. Outcomes indicated a plausible role of HPV in Indian BC patients.

Viral E6 is overexpressed via high viral load in invasive cervical cancer with episomal HPV16

Background

The integration of HR-HPV genome into host DNA is regarded as a key step for the development of cervical cancer. However, HR-HPV genome indeed exists as episome except for integrant. It may be alternative mechanisms in episome-associated carcinogenesis, although, by which HPV 16 episome induces cervical carcinogenesis is unclear now.

Methods

Ninety-three invasive cervical cancer tissues with HPV16 positive were collected. Viral physical status was calculated from comparing E2 to E6-copies and detection of viral load was made with realtime-PCR using copy numbers of E6. HPV16 E6 mRNA transcript levels were measured by realtime-PCR. The methylation frequency of HPV16 promoter was detected by PCR and pyrosequencing.

Results

In 93 samples, 21.5% (20/93) presented purely integrated viral genome, 53.8% (50/93) mixed viral genome, and 24.7% (23/93) purely episomal viral genome. Mean E6 expression in samples with purely episomal viral genomes was 7.13-fold higher than that with purely integrated viral genomes. Meanwhile, viral load in samples with purely episomal viral genomes was 4.53-fold higher than that with purely integrated viral genomes. E6 mRNA expression increased with the viral load in purely episomal cases. There were no differences of mean methylation frequency between purely episomal and integrated virus and among five CpG positions of HPV16 promoter for all samples. And there also was no correlation between E6 mRNA expression and methylation of HPV16 promoter among all samples with purely HPV16 episomal virus.

Conclusions

HPV16 with the purely episomal viral genomes exists in a definite proportion of invasive cervical cancer, and episomal HPV16 also overexpresses E6 mRNA, probably through a high level of viral load.

Identification of Changes in the Human Papilloma Virus 16 (HPV16) Genome During Early Dissemination of Cervical Cancer Cells May Complement Histological Diagnosis of Lymph Node Metastasis

Cancer of the uterine cervix (CACX) is one of the most common carcinoma affecting women worldwide. During treatment, histologically lymph node (LN) metastasis and presence of HPV DNA in blood plasma act as a major prognostic factor. Despite the lack of apparent LN involvement, some early-invasive CACX patients have shown recurrences and poor survival. This is suggestive of undetected early dissemination of cancer cells characterized by presence of HPV DNA in histologically non-metastatic LNs which finally progresses into histologically visible metastasis. This present study investigated the status and origin of HPV genome during early dissemination by molecular analysis in primary tumor (PT), histologically non-metastatic pelvic lymph nodes (LNs) and blood plasma (BP) of same patient. First, CACX patients showing signs of early dissemination was identified by detection of HPV in PT (n = 22) and their corresponding histologically non-metastatic pelvic LNs (n = 45) and BP (n = 18) followed by typing of HPV16/18. This was followed by comparative analysis of the physical, copy number and methylation (enhancer/early/late) status of HPV16 genome present in LNs and BP with that of PT. Our study revealed for the first time that the HPV16 genome were frequently present in the integrated form though the copy number was low in both non-metastatic LNs and BP. However, the methylation pattern of PT was discordant with that of corresponding LNs and BP in majority of the cases. Critical assessment of HPV16 profiles established that the presence of hrHPV may be due to the early dissemination of PT cells having significant pathological implications.

Alteration of Human Papillomavirus Type 16 Genetic and Epigenetic Profiles in Cervical Cancer Patients Is Indicative of Poor Disease Prognosis: A Cohort Analysis

Objective

Aim of this study was to assess the changes in genetic and epigenetic profiles of human papillomavirus type 16 (HPV16), if any, in primary cervical cancer (CaCx) and corresponding plasma before and after therapy for possible prognostic evaluation.

Methods

The genetic (integration status) and epigenetic (methylation of enhancer, early promoter, and late promoter sequences) profiles of HPV16 were analyzed in pretherapy CaCx (n = 46), corresponding plasma, posttherapy cervical swabs (n = 39), and corresponding plasma from a single patient cohort. Quantitative viral load was also measured in these HPV16-positive primary CaCx and posttherapy cervical swabs.

Results

Presence of HPV16 in the patients’ plasma before/after therapy was significantly (P= 0.03) associated with higher viral load in the primary tumor site. Human papillomavirus type 16 integration and hypomethylation of the early (14 of 29,Z= 4.47,P< 0.01) and late promoters (20 of 29,Z= 3.74,P< 0.01) were more prevalent in the plasma than the corresponding pretherapy CaCx samples. However, the dissimilarity in integration status (5 of 24) was less evident between posttherapy cervical swabs and corresponding plasma, although hypomethylation of the early promoter and hypermethylation of the late promoter (8 of 24,Z= 2.6,P< 0.01) was seen in posttherapy plasma samples. Whereas in the posttherapy swabs, integrated (22 of 29) or mixed (7 of 29) form of HPV16 prevailed with hypomethylation of the enhancer (6 of 29,Z= 2.0,P< 0.05) and late promoter (18 of 29,Z= 4.4,P< 0.01) compared with the corresponding primary tumors. The patients having high HPV16 copy number in pretherapy and posttherapy cervical lesions and hypomethylation of early promoter/late promoter in the corresponding plasma showed increased disease recurrence with distant metastases.

Conclusions

The genetic-epigenetic profile of HPV16 in pretherapy/posttherapy CaCx samples showed significant association with disease prognosis.