Renske D.M. Steenbergen

HPV-mediated cervical carcinogenesis : concepts and clinical implications

Persistent infection with a high‐risk human papillomavirus (hrHPV) is generally accepted as a necessary cause of cervical cancer. However, cervical cancer is a rare complication of an hrHPV infection since most such infections are transient, not even giving rise to cervical lesions. On average, it takes 12–15 years before a persistent hrHPV infection may ultimately, via consecutive premalignant stages (ie CIN lesions), lead to an overt cervical carcinoma. This argues that HPV‐induced cervical carcinogenesis is multi‐step in nature. In this review, the data from hrHPV‐mediated in vitro transformation studies and those obtained from analysis of clinical specimens have been merged into a cervical cancer progression model. According to this model, a crucial decision maker in the early stages following infection involves individual susceptibility for certain HPV types depending on the genetic make‐up of immune surveillance determinants. Once a CIN lesion has developed, altered transcriptional regulation of the viral E6/E7 oncogenes, resulting in genomic instability and distinguishing the process of cell transformation from a productive viral infection, probably provides the subsequent important step towards malignancy. The additional (epi)genetic alterations that subsequently accumulate in high‐grade CIN lesions may result in overt malignancy via immortality and growth conditions that gradually become less sensitive to growth‐modulating influences mediated by cytokines and cell–cell and cell–matrix adhesions. The potential implications of hrHPV testing and some other biomarkers deduced from this model for cervical screening and the clinical management of CIN disease are also discussed. Copyright

Methylation-mediated silencing and tumour suppressive function of hsa-miR-124 in cervical cancer

BackgroundA substantial number of microRNAs (miRNAs) is subject to epigenetic silencing in cancer. Although epigenetic silencing of tumour suppressor genes is an important feature of cervical cancer, little is known about epigenetic silencing of miRNAs. Since DNA methylation-based silencing of hsa-miR-124 occurs in various human cancers, we studied the frequency and functional effects of hsa-miR-124 methylation in cervical carcinogenesis.ResultsQuantitative MSP analysis of all 3 loci encoding the mature hsa-miR-124 (hsa-miR-124-1/-2/-3) showed methylation in cervical cancer cell lines SiHa, CaSki and HeLa as well as in late passages of human papillomavirus (HPV) type 16 or 18 immortalised keratinocytes. Treatment of SiHa cells with a demethylating agent reduced hsa-miR-124 methylation levels and induced hsa-miR-124 expression. In HPV-immortalised keratinocytes increased methylation levels were related to reduced hsa-miR-124 expression and higher mRNA expression of IGFBP7, a potential hsa-miR-124 target gene. Ectopic hsa-miR-124 expression in SiHa and CaSki cells decreased proliferation rates and migratory capacity. Combined hsa-miR-124-1 and/or hsa-miR-124-2 methylation analysis of 139 cervical tissue specimens showed an increasing methylation frequency from 0% in normal tissues up to 93% in cervical carcinomas. Increased methylation levels of hsa-miR-124-1 and hsa-miR-124-2 were significantly correlated with reduced hsa-miR-124 expression in cervical tissue specimens. Combined hsa-miR-124-1 and/or hsa-miR-124-2 methylation analysis of 43 cervical scrapes of high-risk HPV positive women was predictive of underlying high-grade lesions.ConclusionsDNA methylation-based silencing of hsa-miR-124 is functionally involved in cervical carcinogenesis and may provide a valuable marker for improved detection of cervical cancer and its high-grade precursor lesions.

Clinical implications of (epi)genetic changes in HPV-induced cervical precancerous lesions.

Infection of cervical epithelium with high-risk human papilloma virus (hrHPV) might result in productive or transforming cervical intraepithelial neoplasia (CIN) lesions, the morphology of which can overlap. In transforming CIN lesions, aberrations in host cell genes accumulate over time, which is necessary for the ultimate progression to cancer. On the basis of (epi)genetic changes, early and advanced transforming CIN lesions can be distinguished. This paves the way for new molecular tools for cervical screening, diagnosis and management of cervical cancer precursor lesions.

Sequential gene promoter methylation during HPV-induced cervical carcinogenesis.

We aimed to link DNA methylation events occurring in cervical carcinomas to distinct stages of HPV-induced transformation. Methylation specific-multiplex ligation-dependent probe amplification (MS-MLPA) analysis of cervical carcinomas revealed promoter methylation of 12 out of 29 tumour suppressor genes analysed, with MGMT being most frequently methylated (92%). Subsequently, consecutive stages of HPV16/18-transfected keratinocytes (n=11), ranging from pre-immortal to anchorage-independent phenotypes, were analysed by MS-MLPA. Whereas no methylation was evident in pre-immortal cells, progression to anchorage independence was associated with an accumulation of frequent methylation events involving five genes, all of which were also methylated in cervical carcinomas. TP73 and ESR1 methylation became manifest in early immortal cells followed by RARβ and DAPK1 methylation in late immortal passages. Complementary methylation of MGMT was related to anchorage independence. Analysis of nine cervical cancer cell lines, representing the tumorigenic phenotype, revealed in addition to these five genes frequent methylation of CADM1, CDH13 and CHFR. In conclusion, eight recurrent methylation events in cervical carcinomas could be assigned to different stages of HPV-induced transformation. Hence, our in vitro model system provides a valuable tool to further functionally address the epigenetic alterations that are common in cervical carcinomas.

Clonal Selection for Transcriptionally Active Viral Oncogenes during Progression to Cancer

ABSTRACT Primary keratinocytes immortalized by human papillomaviruses (HPVs), along with HPV-induced cervical carcinoma cell lines, are excellent models for investigating neoplastic progression to cancer. By simultaneously visualizing viral DNA and nascent viral transcripts in interphase nuclei, we demonstrated for the first time a selection for a single dominant papillomavirus transcription center or domain (PVTD) independent of integrated viral DNA copy numbers or loci. The PVTD did not associate with several known subnuclear addresses but was almost always perinucleolar. Silent copies of the viral genome were activated by growth in the DNA methylation inhibitor 5-azacytidine. HPV-immortalized keratinocytes supertransduced with HPV oncogenes and selected for marker gene coexpression underwent crisis, and the surviving cells transcribed only the newly introduced genes. Thus, transcriptional selection in response to environmental changes is a dynamic process to achieve optimal gene expression for cell survival. This phenomenon may be critical in clonal selection during carcinogenesis. Examination of HPV-associated cancers supports this hypothesis.

Combined Promoter Methylation Analysis of CADM1 and MAL: An Objective Triage Tool for High-Risk Human Papillomavirus DNA–Positive Women

Purpose: Screening women for high-grade cervical intraepithelial neoplasia or cervical cancer (CIN3+) by high-risk human papillomavirus (hrHPV) testing has as side-effect the detection of hrHPV-positive women without clinically relevant lesions. Here, we developed an objective assay assessing the methylation status of the promoter regions of CADM1 and MAL to triage hrHPV-positive women for CIN3+. Experimental Design: In a training set (51 women with CIN3+ and 224 without CIN2+), panels consisting of one to four quantitative methylation-specific PCR (qMSP) assays (CADM1-m12,CADM1-m18,MAL-m1,MAL-m2) were analyzed. Cross-validated receiver-operating characteristics (ROC) curves were constructed and the panel with highest partial cross-validated area under the curve (AUC) was used for validation in an independent set of 236 consecutive hrHPV-positive women from a screening cohort. In the validation set, the ROC curve of the panel was compared with CIN3+ sensitivity and specificity of cytology and of cytology combined with HPV16/18 genotyping. Results: In the training set, CADM1-m18 combined with MAL-m1 was the best panel (cross-validated partial AUC = 0.719). In the validation set, this panel revealed CIN3+ sensitivities ranging from 100% (95% CI: 92.4–100) to 60.5% (95% CI: 47.1–74.6), with corresponding specificities ranging from 22.7% (95% CI: 20.2–25.2) to 83.3% (95% CI: 78.4–87.4). For cytology these were 65.8% (95% CI: 52.3–79.0) and 78.8% (95% CI: 73.7–83.1) and for cytology/HPV16/18, these were 84.2% (95% CI: 72.0–92.7) and 54.0% (95% CI: 49.2–58.7), respectively. The point estimates of both cytology and cytology/HPV16/18 were equal to the values of the ROC curve of CADM1-m18/MAL-m1. Conclusions: We developed an objective methylation marker panel that was equally discriminatory for CIN3+ as cytology or cytology with HPV16/18 genotyping in hrHPV-positive women. This opens the possibility for complete cervical screening by objective, nonmorphological molecular methods. Clin Cancer Res; 17(8); 2459–65. ©2011 AACR.

Altered microRNA expression associated with chromosomal changes contributes to cervical carcinogenesis

Little is known about the alterations in microRNA (miRNA) expression patterns during the consecutive stages of cervical cancer development and their association with chromosomal instability. In this study, miRNA expression in normal cervical squamous epithelium, high-grade precancerous lesions (cervical intraepithelial neoplasia (CIN2–3)), squamous cell carcinomas (SCCs) and adenocarcinomas (AdCAs) was integrated with previously generated chromosomal profiles of the same samples. Significantly differential expression during the consecutive stages of cervical SCC development was observed for 106 miRNAs. Of these differentially expressed miRNAs, 27 showed early transiently altered expression in CIN2–3 lesions only, 46 miRNAs showed late altered expression in SCCs only and 33 showed continuously altered expression in both CIN2–3 and SCCs. Altered expression of five significantly differentially expressed miRNAs, hsa-miR-9 (1q23.2), hsa-miR-15b (3q25.32), hsa-miR-28-5p (3q27.3), hsa-miR-100 and hsa-miR-125b (both 11q24.1), was directly linked to frequent chromosomal alterations. Functional analyses were performed for hsa-miR-9, representing a potential oncogene with increased expression linked to a chromosomal gain of 1q. Hsa-miR-9 overexpression was found to increase cell viability, anchorage-independent growth and migration in vitro. Upon organic raft culturing, hsa-miR-9 hampered differentiation and induced proliferation in all strata of the epithelial layer. These findings support a potential oncogenic function of hsa-miR-9 in cervical cancer. In summary, differential expression of 106 miRNAs, partly associated with chromosomal alterations, was observed during cervical SCC development. Altered expression of hsa-miR-9 associated with a chromosomal gain of chromosome 1q was shown to be functionally relevant, underlining the importance of deregulated miRNA expression in cervical carcinogenesis.

Association between dense CADM1 promoter methylation and reduced protein expression in high-grade CIN and cervical SCC†

We previously showed that silencing of TSLC1, recently renamed CADM1, is functionally involved in high‐risk HPV‐mediated cervical carcinogenesis. CADM1 silencing often results from promoter methylation. Here, we determined the extent of CADM1 promoter methylation in cervical (pre)malignant lesions and its relation to anchorage‐independent growth and gene silencing to select a CADM1‐based methylation marker for identification of women at risk of cervical cancer. Methylation‐specific PCRs targeting three regions within the CADM1 promoter were performed on high‐risk HPV‐containing cell lines, PBMCs, normal cervical smears, and (pre)malignant lesions. CADM1 protein expression in cervical tissues was analysed by immunohistochemistry. All statistical tests were two‐sided. Density of methylation was associated with the degree of anchorage‐independent growth and CADM1 gene silencing in vitro. In cervical squamous lesions, methylation frequency and density increased with severity of disease. Dense methylation (defined as ≥ 2 methylated regions) increased from 5% in normal cervical samples to 30% in CIN3 lesions and 83% in squamous cell carcinomas (SCCs) and was significantly associated with decreased CADM1 protein expression (p < 0.00005). The frequency of dense methylation was significantly higher in ≥ CIN3 compared with ≤ CIN1 (p = 0.005), as well as in SCCs compared with adenocarcinomas (83% versus 23%; p = 0.002). Detection of dense CADM1 promoter methylation will contribute to the assembly of a valuable marker panel for the triage of high‐risk HPV‐positive women at risk of ≥ CIN3. Copyright

Triage by methylation-marker testing versus cytology in women who test HPV-positive on self-collected cervicovaginal specimens (PROHTECT-3): a randomised controlled non-inferiority trial

BACKGROUND Cytology is a widely used method of triaging women who test positive for human papillomavirus (HPV). However, self-sampled specimens, which can substantially increase participation in screening programmes, are not suitable for accurate cytological assessment. We investigated whether direct DNA methylation-based molecular triage on self-sampled cervicovaginal specimens was non-inferior to cytology triage on additional physician-collected cervical samples in the detection of cervical intraepithelial neoplasia grade 2 (CIN2) or worse in women who did not attend cervical screening programmes. METHODS In this randomised controlled non-inferiority trial, we invited women (aged 33-63 years) registered as non-attendees of cervical screening in the Netherlands in 2007 to submit a self-collected cervicovaginal sample for HPV testing. Using a computer-generated sequence, we randomly allocated women who tested positive for high-risk hrHPV on a self-sample to either triage by cytology on an additional physician-taken smear or direct triage on the self-sample by methylation analysis of MAL and miR-124-2 genes (1:1; stratified by age and region, with block sizes by age group). Triage-positive women in either group were referred for colposcopy. The primary endpoint was detection of CIN2 or worse, analysed by intention to treat. The non-inferiority margin was 0·80. This study is registered in the Primary Trial Register of the Netherlands, number NTR6026. FINDINGS We invited 46,001 women to participate, 12,819 of whom returned self-sampled material; 1038 samples tested positive for high-risk HPV. Between Nov 1, 2010, and Dec 31, 2011, after exclusion of women who were ineligible, we enrolled and randomly allocated 515 women to methylation triage and 509 to cytology triage. The detection of CIN2 or worse with methylation triage was non-inferior to that with cytology triage (90 [17%] of 515 women vs 75 [15%] of 509 women; relative risk 1·19, 95% CI 0·90-1·57). Referral for colposcopy was more common in the molecular group (284 [55%] women) than in the cytology group (149 [29%] women; p<0·0001). Mean time to CIN2 or worse diagnosis was shorter in the molecular triage group (96 days, range 44-101) than in the cytology triage group (158 days, 71-222; p=0·00084). INTERPRETATION DNA methylation analysis of MAL and miR-124-2 genes on HPV-test-positive self-samples is non-inferior to cytology triage in the detection of CIN2 or worse, opening the way to full molecular screening. FUNDING Midden-West and Oost Screening Organisations and Stichting Achmea Gezondheidszorg.

Combined CADM1 and MAL promoter methylation analysis to detect (pre‐)malignant cervical lesions in high‐risk HPV‐positive women

Given the lower specificity for high‐grade cervical lesions of high‐risk human papillomavirus (hrHPV) testing compared to cytology, additional triage testing for hrHPV test‐positive women is needed to detect high‐grade cervical lesions. Here, we tested whether combined methylation analysis for cell adhesion molecule 1 (CADM1) and T‐lymphocyte maturation associated protein (MAL), both functionally involved in cervical carcinogenesis, could serve as such a triage marker. Four quantitative methylation‐specific PCRs (qMSP), two for CADM1 (regions M12 and M18) and MAL (regions M1 and M2) each, were applied to 261 cervical tissue specimens ranging from no neoplasia to carcinoma. When qMSPs were combined and positivity for at least one of the qMSPs in the combination was taken into account, the highest positivity rates for cervical intraepithelial neoplasia grade 3 (CIN3) lesions (97%) and squamous cell‐ and adeno‐carcinomas (99%) were obtained by combining a single CADM1 marker with a single MAL marker. Subsequent qMSP analysis of 70 GP5+/6+‐PCR hrHPV‐positive scrapings revealed that a two‐marker panel consisting of CADM1‐M18 and MAL‐M1 was most discriminative, detecting 90% of women with CIN3 (n = 30), whereas it showed a positive result in only 13.5% of women without cervical disease (n = 40). Finally, we applied hrHPV GP5+/6+‐PCR testing followed by CADM1‐M18/MAL‐M1 methylation analysis to a cohort of 79 women visiting the outpatient colposcopy clinic. hrHPV testing revealed a sensitivity of 97% and a specificity of 33% for CIN3+. Additional CADM1‐M18/MAL‐M1 methylation analysis on the hrHPV‐positive women increased the specificity to 78% with a sensitivity of 70%. In conclusion, the methylation marker panel CADM1‐M18 and MAL‐M1 may serve as an alternative molecular triage tool for hrHPV‐positive women.