Human papillomavirus's physical state and cyclin A1 promoter methylation in cervical cancer

New insights for gynecological cancer therapies: from molecular mechanisms and clinical evidence to future directions

Advanced and recurrent gynecological cancers lack effective treatment and have poor prognosis. Besides, there is urgent need for conservative treatment for fertility protection of young patients. Therefore, continued efforts are needed to further define underlying therapeutic targets and explore novel targeted strategies. Considerable advancements have been made with new insights into molecular mechanisms on cancer progression and breakthroughs in novel treatment strategies. Herein, we review the research that holds unique novelty and potential translational power to alter the current landscape of gynecological cancers and improve effective treatments. We outline the advent of promising therapies with their targeted biomolecules, including hormone receptor-targeted agents, inhibitors targeting epigenetic regulators, antiangiogenic agents, inhibitors of abnormal signaling pathways, poly (ADP-ribose) polymerase (PARP) inhibitors, agents targeting immune-suppressive regulators, and repurposed existing drugs. We particularly highlight clinical evidence and trace the ongoing clinical trials to investigate the translational value. Taken together, we conduct a thorough review on emerging agents for gynecological cancer treatment and further discuss their potential challenges and future opportunities.

HPV-related methylation-based reclassification and risk stratification of cervical cancer

Human papillomavirus (HPV) is a clear etiology of cervical cancer (CC). However, the associations between HPV infection and DNA methylation have not been thoroughly investigated. Additionally, it remains unknown whether HPV‐related methylation signatures can identify subtypes of CC and stratify the prognosis of CC patients. DNA methylation profiles were obtained from The Cancer Genome Atlas to identify HPV‐related methylation sites. Unsupervised clustering analysis of HPV‐related methylation sites was performed to determine the different CC subtypes. CC patients were categorized into cluster 1 (Methylation‐H), cluster 2 (Methylation‐M), and cluster 3 (Methylation‐L). Compared to Methylation‐M and Methylation‐L, Methylation‐H exhibited a significantly improved overall survival (OS). Gene set enrichment analysis (GSEA) was conducted to investigate the functions that correlated with different CC subtypes. GSEA indicated that the hallmarks of tumors, including KRAS signaling, TNFα signaling via NF‐κB, inflammatory response, epithelial–mesenchymal transition, and interferon‐gamma response, were enriched in Methylation‐M and Methylation‐L. Based on mutation and copy number variation analyses, we found that aberrant mutations, amplifications, and deletions among the MYC, Notch, PI3K‐AKT, and RTK‐RAS pathways were most frequently detected in Methylation‐H. Additionally, mutations, amplifications, and deletions within the Hippo, PI3K‐AKT, and TGF‐β pathways were presented in Methylation‐M. Genes within the cell cycle, Notch, and Hippo pathways possessed aberrant mutations, amplifications, and deletions in Methylation‐L. Moreover, the analysis of tumor microenvironments revealed that Methylation‐H was characterized by a relatively low degree of immune cell infiltration. Finally, a prognostic signature based on six HPV‐related methylation sites was developed and validated. Our study revealed that CC patients could be classified into three heterogeneous clusters based on HPV‐related methylation signatures. Additionally, we derived a prognostic signature using six HPV‐related methylation sites that stratified the OS of patients with CC into high‐ and low‐risk groups.

Promoter methylation of tumor suppressor genes induced by human papillomavirus in cervical cancer

Cervical cancer is the most fourth common cancer in women worldwide. The E6 and E7 high-risk human papillomavirus (HPV) types are the main cause of this cancer. Several studies have revealed that promoter methylation of tumor suppressor genes is induced by HPV E7. Recently, it was found that HPV16-E7 and the DNA methyltransferase 1 complex could bind at the cyclin A1 (CCNA1) promoter, resulting in CCNA1 promoter methylation. Therefore, there is a need to study other tumor suppressor genes for which HPV may induce promoter methylation. The present study investigated whether HPV induced cell adhesion molecule 1 (CADM1) and death associated protein kinase 1 (DAPK1) promoter methylation. C33a (no HPV infection) and SiHa (HPV 16 infection) cell lines were used for methylation status and expression observation. It was found that CADM1 and DAPK1 promoter methylation, no expression of CADM1 and decreased expression of DAPK1, was presented in SiHa cells. While no promoter methylation of these two genes was observed in C33a cells, with positive expression of the genes. It was subsequently investigated whether E6 and/or E7 could induce promoter methylation and decrease the expression of these two genes. Methylation-specific primer PCR and quantitative PCR were performed to elucidate the promoter methylation status and expression of CADM1 and DAPK1 in C33a cells transfected with HPV16 E6-PCDNA3 or HPV16 E7-PCDNA3.1 myc-his, compared to empty vector-transfected cells. The results showed that HPV E7 could induce CADM1 promoter methylation and decrease the gene expression in HPV E7 transfected C33a cells, while HPV E6 could induce DAPK1 promoter methylation and decrease its expression in C33a cells transfected with HPV E6. Finally, the mechanism by which HPV E7 induced CADM1 promoter methylation was observed by performing chromatin immunoprecipitation; the data showed that E7 induced CADM1 methylation by the same mechanism as that for CCNA1, by binding at the CADM1 promoter, resulting in the subsequent reduction of its expression in cervical cancer.

Value of CCNA1 promoter methylation in triaging ASC-US cytology

BACKGROUND

<br />Using HPV testing to triage ASC-US still has some problems of unnecessary colposcopy in many cases. A previous study reported that methylation of CCNA1, a tumor suppressor gene, can differentiate between low and high grade lesions. This study was designed to evaluate the diagnostic values and application of CCNA1 methylation in the patients with ASC-US group.<br />Materials and methods:<br />Cross sectional analytic study was conducted in the patients with <br />ASC-US cytology. HPV DNA testing and CCNA1 promoter methylation testing were performed. The patients were sent for colposcopic examination and biopsy. Biopsy results were considered as gold standard. Diagnostic test of HPV test and CCNA1 methylation test were calculated for sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), likelihood ratio for test positive and negative and 95% confidence interval.<br />Results:<br />One hundred and seventy patients were enrolled. Mean age was 39.7 years old. HR-HPV was positive in 70% of the patients. HPV type 16, type 18 and non-16,18 were 12.4%, 4.7% and 42.4%, respectively. CIN2+ were found in 12.4% (21 cases). CCNA1 promoter methylation was positive in 5 cases. CCNA1 had high specificity 99.3%, NPV 89.2% and PPV 80% in detection of CIN2+ but sensitivity was 19%. Likelihood ratio for positive test was 28.4 and likelihood ratio for negative test was 0.8. HPV test had sensitivity of 90.5% and NPV of 95.9% but low specificity and PPV as 31.5% and 15.7%, respectively.<br />Conclusion:<br /> CCNA1 promoter methylation testing had very high specificity, likelihood ratio for the positive test and PPV (99.3%, 28.4 and 80.0, respectively). Therefore, CCNA1 promoter methylation test may be used in the HPV DNA positive cases to classify the urgency of colposcopy and the colposcopist should pay more attention to CCNA1 positive patients because of their higher chance to identify the significant lesions.

Human papillomavirus type 16 E7 oncoprotein mediates CCNA1 promoter methylation

Human papillomavirus (HPV) oncoproteins drive distinctive promoter methylation patterns in cancer. However, the underlying mechanism remains to be elucidated. Cyclin A1 (CCNA1) promoter methylation is strongly associated with HPV-associated cancer. CCNA1 methylation is found in HPV-associated cervical cancers, as well as in head and neck squamous cell cancer. Numerous pieces of evidence suggest that E7 may drive CCNA1 methylation. First, the CCNA1 promoter is methylated in HPV-positive epithelial lesions after transformation. Second, the CCNA1 promoter is methylated at a high level when HPV is integrated into the human genome. Finally, E7 has been shown to interact with DNA methyltransferase 1 (Dnmt1). Here, we sought to determine the mechanism by which E7 increases methylation in cervical cancer by using CCNA1 as a gene model. We investigated whether E7 induces CCNA1 promoter methylation, resulting in the loss of expression. Using both E7 knockdown and overexpression approaches in SiHa and C33a cells, our data showed that CCNA1 promoter methylation decreases with a corresponding increase in expression in E7 siRNA-transfected cells. By contrast, CCNA1 promoter methylation was augmented with a corresponding reduction in expression in E7-overexpressing cells. To confirm whether the binding of the E7-Dnmt1 complex to the CCNA1 promoter induced methylation and loss of expression, ChIP assays were carried out in E7-, del CR3-E7 and vector control-overexpressing C33a cells. The data showed that E7 induced CCNA1 methylation by forming a complex with Dnmt1 at the CCNA1 promoter, resulting in the subsequent reduction of expression in cancers. It is interesting to further explore the genome-wide mechanism of E7 oncoprotein-mediated DNA methylation.

CCNA1 promoter methylation: a potential marker for grading Papanicolaou smear cervical squamous intraepithelial lesions

BACKGROUND

From our previous study, we established that cyclin A1 (CCNA1) promoter methylation is strongly correlated with multistep progression of HPV-associated cervical cancer, suggesting potential use as a diagnostic maker of disease.

OBJECTIVES

The purpose of the present study was to assess the prevalence of CCNA1 promoter methylation in residual cervical cells isolated from liquid-based cytology that underwent hrHPV DNA screening for cervical cancer, and then to evaluate this marker for diagnostic accuracy using parameters like sensitivity, specificity, predictive values and likelihood ratio.

METHODS

In this retrospective study, histopathology was used as the gold standard method with specimens separated into the following groups: negative (n=31), low- grade squamous intraepithelial lesions (LSIL, n=34) and high-grade squamous intraepithelial lesions or worse (HSIL+, n=32). The hrHPV was detected by Hybrid Capture 2 (HC2) and CCNA1 promoter methylation was examined by CCNA1 duplex methylation specific PCR.

RESULTS

The results showed the frequencies of CCNA1 promoter methylation were 0%, 5.88% and 83.33%, while the percentages of hrHPV were 66.67%, 82.35% and 100% in the negative, LSIL and HSIL+ groups, respectively. Although hrHPV infection showed high frequency in all three groups, it could not differentiate between the different groups and grades of precancerous lesions. In contrast, CCNA1 promoter methylation clearly distinguished between negative/LSIL and HSIL+, with high levels of all statistic parameters.

CONCLUSION

CCNA1 promoter methylation is a potential marker for distinguishing between histologic negative/LSIL and HSIL+using cervical cytology samples.

DNA Methylation and Flavonoids in Genitourinary Cancers

Malignancies of the genitourinary system have some of the highest cancer incidence and mortality rates. For example prostate cancer is the second most common cancer in men and ovarian cancer mortality and incidence are near equal. In addition to genetic changes modulation of the epigenome is critical to cancer development and progression. In this regard epigenetic changes in DNA methylation state and DNA hypermethylation in particular has garnered a great deal of attention. While hypomethylation occurs mostly in repeated sequence such as tandem and interspersed repeats and segment duplications, hypermethylation is associated with CpG islands. Hypomethylation leads to activation of cancer-causing genes with global DNA hypomethylation being commonly associated with metastatic disease. Hypermethylation-mediated silencing of tumor suppressive genes is commonly associated with cancer development. Bioactive phytochemicals such as flavonoids present in fruits, vegetables, beverages etc. have the ability to modulate DNA methylation status and are therefore very valuable agents for cancer prevention. In this review we discuss several commonly methylated genes and flavonoids used to modulate DNA methylation in the prevention of genitourinary cancers.

Methylation in the promoters of HS3ST2 and CCNA1 genes is associated with cervical cancer in Uygur women in Xinjiang

We assessed the suitability of HS3ST2 and CCNA1 genes as biomarkers for the early detection of cervical cancer in Uygur women in Xinjiang, China. Methylation-specific PCR (MSP) and HPV (HPV16 and HPV18)-specific PCR were performed on 110 cervical samples: 40 normal cervices, 10 cervical intraepithelial neoplasia 1 (CIN1), 10 CIN2, 10 CIN3 and 40 cervical cancer tissues. The expression of the 2 genes was measured by reverse transcription PCR (RT-PCR) in 10 methylation-positive and 10 methylation-negative cervical tissues. We found that both HS3ST2 and CCNA1 genes were methylated in 38 of the 40 cervical cancer tissues, 9 of the 10 CIN3, and 6 of the 10 CIN2. In contrast, methylation of these 2 genes was found in only 1 of the 40 normal tissues and none of 10 CIN1. Furthermore, hypermethylated HS3ST2 and CCNA1 genes were correlated with infection with HPV16 and HPV18 in high-grade squamous intraepithelial lesions (HSILs) and cervical cancer (both p<0.05). The expression of HS3ST2 and CCNA1 genes was lower in the methylation-positive cervical tissues than in the methylation-negative cervical tissues. Our results indicate that HS3ST2 and CCNA1 genes may play important roles in HPV-induced cervical cancer and that patients with specific hypermethylated genes may have a greater risk of progressing to invasive cervical cancer.

Genome-wide DNA methylation assay reveals novel candidate biomarker genes in cervical cancer

The oncogenic human papilloma viruses (HPVs) are associated with precancerous cervical lesions and development of cervical cancer. The DNA methylation signatures of the host genome in normal, precancerous and cervical cancer tissue may indicate tissue-specific perturbation in carcinogenesis. The aim of this study was to identify new candidate genes that are differentially methylated in squamous cell carcinoma compared with DNA samples from cervical intraepithelial neoplasia grade 3 (CIN3) and normal cervical scrapes. The Illumina Infinium HumanMethylation450 BeadChip method identifies genome-wide DNA methylation changes in CpG islands, CpG shores and shelves. Our findings showed an extensive differential methylation signature in cervical cancer compared with the CIN3 or normal cervical tissues. The identified candidate biomarker genes for cervical cancer represent several types of mechanisms in the cellular machinery that are epigenetically deregulated by hypermethylation, such as membrane receptors, intracellular signaling and gene transcription. The results also confirm extensive hypomethylation of genes in the immune system in cancer tissues. These insights into the functional role of DNA methylome alterations in cervical cancer could be clinically applicable in diagnostics and prognostics, and may guide the development of new epigenetic therapies.

Protein expression and promoter methylation of the candidate biomarker TCF21 in head and neck squamous cell carcinoma

PURPOSE

Epigenetic alterations of the transcription factor 21 (TCF21) gene have been associated with head and neck squamous cell carcinoma (HNSCC) and other tumor entities. So far, however, no reports have appeared in the literature on TCF21 protein expression in HNSCC and its relevance as a putative biomarker.

METHODS

TCF21 protein expression was assessed in 74 HNSCCs and 31 benign tonsils by immunohistochemistry. Methylation analyses of the corresponding gene promoter were performed in 45 HNSCCs and 31 benign tonsils. The TCF21 expression levels in the tumors and controls were compared with each other and within each group and, in addition, with the TCF21 promoter methylation status and various clinicopathological characteristics.

RESULTS

Overall, both the expression levels and methylation frequencies of TCF21 were significantly higher in the HNSCCs than in the benign controls (p < 0.001 each). Specifically, TCF21 promoter hypermethylation resulted in a reduced protein expression in a subgroup of the HNSCCs (p = 0.038), but not in the tonsils. In the tonsils, TCF21 protein expression positively correlated with that of CD31 (p = 0.039), a marker for blood vessels. Also, in the tonsils the TCF21 protein methylation frequency showed a positive correlation with age (p = 0.008). The HNSCCs of patients with a positive history for alcohol and nicotine abuse showed higher TCF21 protein expression levels than their respective counterparts (p = 0.028 and p = 0.062, respectively). The same was observed in human papilloma virus (HPV)-negative tumors (p = 0.042), tumors located in the oral cavity (p = 0.016) and early-stage tumors (p = 0.025). Interestingly, expression rates in tumors of the oropharynx, where HPV-positive tumors were most frequently found, tended to be lower (p = 0.065). The methylation frequencies of TCF21 were found to be significantly higher in tumors of patients without nicotine abuse (p = 0.030), in HPV-positive tumors (p = 0.014) and in tumors exhibiting over-expression of p16, a protein induced by HPV (p = 0.006).

CONCLUSIONS

Both over-expression and increased promoter methylation of TCF21 were frequently observed in HNSCCs. TCF21 promoter hypermethylation was found to lead to gene silencing in the HNSCCs, but not in the benign tonsils. These epigenetic, and possibly also genetic, alterations of the TCF21 gene in HNSCCs may be driven by HPV infection, nicotine and alcohol abuse, or both. These findings, together with its stage- and primary site-dependent expression, turn TCF21 into a promising candidate biomarker in HNSCC.

Sp1 transcription factor and GATA1 cis-acting elements modulate testis-specific expression of mouse cyclin A1

Cyclin A1 is a male germ cell-specific cell cycle regulator that is essential for spermatogenesis. It is unique among the cyclins by virtue of its highly restricted expression in vivo, being present in pachytene and diplotene spermatocytes and not in earlier or later stages of spermatogenesis. To begin to understand the molecular mechanisms responsible for this narrow window of expression of the mouse cyclin A1 (Ccna1) gene, we carried out a detailed analysis of its promoter. We defined a 170-bp region within the promoter and showed that it is involved in repression of Ccna1 in cultured cells. Within this region we identified known cis-acting transcription factor binding sequences, including an Sp1-binding site and two GATA1-binding sites. Neither Sp1 nor GATA1 is expressed in pachytene spermatocytes and later stages of germ cell differentiation. Sp1 is readily detected at earlier stages of spermatogenesis. Site-directed mutagenesis demonstrated that neither factor alone was sufficient to significantly repress expression driven by the Ccna1 promoter, while concurrent binding of Sp1, and most likely GATA1 and possibly additional factors was inhibitory. Occupancy of Sp1 on the Ccna1 promoter and influence of GATA1-dependent cis-acting elements was confirmed by ChIP analysis in cell lines and most importantly, in spermatogonia. In contrast with many other testis-specific genes, the CpG island methylation status of the Ccna1 promoter was similar among various tissues examined, irrespective of whether Ccna1 was transcriptionally active, suggesting that this regulatory mechanism is not involved in the restricted expression of Ccna1.

Cyclin A1 shows age-related expression in benign tonsils, HPV16-dependent overexpression in HNSCC and predicts lower recurrence rate in HNSCC independently of HPV16

Background

Promoter methylation of the tumor suppressor gene Cyclin A1 could be associated with Human Papillomavirus 16 (HPV16) induced Head and Neck Squamous Cell Carcinoma (HNSCC) and Cervical Carcinoma. There is disagreement about the impact of this epigenetic event on protein expression of Cyclin A1 in malignant and non-malignant tissue and there hardly exists any information about possible relationships between Cyclin A1 expression and clinicopathological characteristics in HNSCC.

Methods

We analyzed protein expression of Cyclin A1 in 81 HNSCC and 74 benign tonsils by immunohistochemistry and correlated it to Cyclin A1 methylation status, presence of HPV16 infection and other clinicopathological characteristics.

Results

Overexpression of Cyclin A1 was more present in HNSCC than in tonsils (p < 0.001). In both entities, HNSCC and benign tonsils, expression of Cyclin A1 significantly correlated with the expression of Cyclin-dependent kinase-inhibitor p16 (p = 0.000672 and 0.00495). In tonsils, expression of Cyclin A1 was inversely proportional to age (p = 0.00000396), and further correlated with expression of tumor suppressor gene p53 (p = 0.000228). In HNSCC Cyclin A1 expression was associated with the presence of HPV16 DNA (p = 0.0014) and a lower recurrence rate in univariate and multivariate analysis (p = 0.002 and 0.013). Neither in HNSCC nor in tonsils Cyclin A1 expression correlated with promoter methylation.

Conclusions

Cyclin A1 is an important cell cycle regulator with age-related increased expression in tonsils of children. HPV16 induces overexpression of Cyclin A1 in HNSCC despite promoter methylation. Overexpression of Cyclin A1 predicts a lower recurrence rate in HNSCC independently of HPV16.