Genotype-specific methylation of HPV in cervical intraepithelial neoplasia

HPV-16 E6 mutation and viral integration related host DNA methylation implicate the development and progression of cervical cancer

BACKGROUND

HPV-16 infection and viral-host integration are the most important risk factors for cervical cancer (CC). The aim of this study is to develop a new molecular strategy integrated both the viral and host genome variations identifying and monitoring CC.

METHOD

A total of 312 methylation and 538 RNA-seq datasets were collected from public databases to identify differentially methylated and expressed genes. HPV associated virus integration sites (VISs) were analysed using the ViMIC database. From September 2020 to August 2021, the 70 HPV-16 positive cases retrospectively collected from multi-centre cohorts were subjected to HPV-16 E6 deep sequencing and PCR-based host gene (ASTN1, DLX1, ITGA4, RXFP3, SOX17, ZNF671) methylation detection. RNAseq and expression validation (NNF671) were performed in C-33A cell line harbouring HPV D32E. Lasso and logistic regression algorithm were used to construct the CC diagnostic model.

RESULTS

A positive correlation was observed between the average methylation level of CC patients and their pathological features including tumour stage (p = 0.0077) and HPV subtype (p < 0.001). ZNF671 was identified as a CC-specific methylation marker, with an impressive 93% sensitivity. Both HPV-16 D32E mutation and integration of HPV-16 down-regulated the ZNF671 expression. Finally, a CC diagnostic nomogram was developed by integrating ZNF671 methylation level and HPV E6 mutation feature, yielding an exceptional AUC of 0.997 (95% CI: 0.934-1.000).

CONCLUSIONS

Our study demonstrated HPV viral mutations are closely related to host gene epigenetic alterations in CC. Integration of the viral and host genetic information might be a new promising strategy for CC screening.

Promoter DNA methylation patterns in oral, laryngeal and oropharyngeal anatomical regions are associated with tumor differentiation, nodal involvement and survival

Differentially methylated regions (DMRs) can be used as head and neck squamous cell carcinoma (HNSCC) diagnostic, prognostic and therapeutic targets in precision medicine workflows. DNA from 21 HNSCC and 10 healthy oral tissue samples was hybridized to a genome-wide tiling array to identify DMRs in a discovery cohort. Downstream analyses identified differences in promoter DNA methylation patterns in oral, laryngeal and oropharyngeal anatomical regions associated with tumor differentiation, nodal involvement and survival. Genome-wide DMR analysis showed 2,565 DMRs common to the three subsites. A total of 738 DMRs were unique to laryngeal cancer (n=7), 889 DMRs were unique to oral cavity cancer (n=10) and 363 DMRs were unique to pharyngeal cancer (n=6). Based on the genome-wide analysis and a Gene Ontology analysis, 10 candidate genes were selected to test for prognostic value and association with clinicopathological features. TIMP3 was associated with tumor differentiation in oral cavity cancer (P=0.039), DAPK1 was associated with nodal involvement in pharyngeal cancer (P=0.017) and PAX1 was associated with tumor differentiation in laryngeal cancer (P=0.040). A total of five candidate genes were selected, DAPK1, CDH1, PAX1, CALCA and TIMP3, for a prevalence study in a larger validation cohort: Oral cavity cancer samples (n=42), pharyngeal cancer tissues (n=25) and laryngeal cancer samples (n=52). PAX1 hypermethylation differed across HNSCC anatomic subsites (P=0.029), and was predominantly detected in laryngeal cancer. Kaplan-Meier survival analysis (P=0.043) and Cox regression analysis of overall survival (P=0.001) showed that DAPK1 methylation is associated with better prognosis in HNSCC. The findings of the present study showed that the HNSCC subsites oral cavity, pharynx and larynx display substantial differences in aberrant DNA methylation patterns, which may serve as prognostic biomarkers and therapeutic targets.

PAX1 and SEPT9 methylation analyses in cervical exfoliated cells are highly efficient for detecting cervical (pre)cancer in hrHPV-positive women

Studies have investigated PAX1 and SEPT methylation were closely associated with cervical cancer. For this study, we verified the expressions of PAX1 and SEPT9 methylation in 236 hrHPV women cervical exfoliated cells by using quantitative methylation-specific PCR and we further explored their diagnostic value in cervical (pre)cancer detection. Our results identified that the methylation rates and levels of PAX1 and SEPT9 increased with cervical lesion severity. For a diagnosis of cervical (pre)cancer, the area under the curve (AUC) of PAX1 methylation was 0.77 (95% CI 0.71-0.83) and the AUC of SEPT9 methylation was 0.86 (95% CI 0.81∼0.90). Analyses of the PAX1 and SEPT9 methylation statuses alone or combined with commonly used tests can efficiently identify cervical (pre)cancer. In particular, SEPT9 methylation might serve as an effective and powerful biomarker for the diagnosis of cervical (pre)cancer and as an alternative triage test in HPV-based cervical (pre)cancer screening programs.Impact StatementWhat is already known on this subject? This subject showed that PAX1 and SEPT9 methylation were closely associated with cervical cancer. The methylation rates and levels of PAX1 and SEPT9 increased with cervical lesion severity and reached a peak in cervical cancer exfoliated cells. We further assessed the diagnostic performances of PAX1 and SEPT9 methylation in cervical cancer screening. In detecting cervical (pre)cancer, the sensitivity values of PAX1 and SEPT9 methylation were up to 61.18% and 82.35%, respectively, and the specificity values of PAX1 and SEPT9 methylation were up to 95.36% and 86.75%, respectively. Moreover, the ROC curve analysis showed AUC values of 0.77 for PAX1 methylation and 0.86 for SEPT9 methylation tests, which were significantly superior to other commonly used tests. These findings suggest that PAX1 and SEPT9 methylation detection may have great clinical potential in cervical cancer screening.What the results of this study add? The rates and levels of PAX1 and SEPT9 methylation increased with the severity of the cervical lesions. For a diagnosis of cervical (pre)cancer, the area under the curve (AUC) of PAX1 methylation was 0.77 (95% CI 0.71-0.83), and the sensitivity and specificity values were 61.18% and 95.36%, respectively. The AUC value of the SEPT9 methylation was 0.86 (95% CI 0.81 ∼ 0.90), and the sensitivity and specificity values were 82.35% and 86.75%, respectively. Compared with the various tests we conducted, the PAX1 methylation showed the highest specificity (95.36%), and the SEPT9 methylation demonstrated the highest accuracy(86.00%).What the implications are of these findings for clinical practice and/or further research? The methylation levels of PAX1 and SEPT9 had a certain predictive effect on the severity of cervical lesions in hrHPV-positive women. In addition, SEPT9 methylation analysis performs better than PAX1 methylation analysis and commonly used tests in cervical exfoliated cells for detecting cervical (pre)cancer in hrHPV-positive women. SEPT9 methylation analysis merits consideration as an effective and objective, alternative triage test in HPV-based cervical (pre)cancer screening programs.

Effects of CpG sites methylation modification of HPV16 integration essential gene on the proliferation of cervical cancer cells

PURPOSE

The mechanism of methylation of HPV CpG sites in the occurrence and prognosis of cervical carcinogenesis remains unclear. We investigated the effects of demethylation of the CpG sites of E2 and E6, essential genes of HPV16 integration, on cervical cancer cell expression, integration, and proliferation.

MATERIALS AND METHODS

HPV16-positive (Caski) cells were treated with different concentrations of the demethylation compound 5-aza-dc (0, 5, 10, 20 μmol/l) in vitro. After the intervention, the methylation statuses of HPV16 E2 and E6 were detected by TBS, the expression levels of E2 and E6 mRNA and protein were detected by real-time PCR and western blot, cell proliferation activity was detected by CCK8, and cell cycle and apoptosis were determined by FCM. GraphPad Prism version 8.4.2 and R version 4.2.3 were used for relevant data analyses.

RESULTS

The methylation levels of HPV16 E2 and E6 CpG sites decreased gradually with increasing 5-aza-dc intervention concentrations. With decreasing E2 and E6 methylation rates, E2 expression increased, the E2/E6 ratio increased, E6 expression decreased, and the growth inhibition rate of Caski cells increased. E2 and E6 expression were negatively and positively correlated with their degrees of methylation respectively, while the E2/E6 mRNA to protein ratio was negatively correlated with the methylation degrees of E2 and E6.

CONCLUSION

Demethylation can be used as a prospective treatment to affect HPV expression and persistent infection, providing a new theoretical basis for the clinical treatment of viral infections.

A systematic review and meta-analysis of the diagnostic effectiveness of human papillomavirus methylation biomarkers for detection of cervical cancer

Background: The aim of this systematic review and meta-analysis was to assess the evidence for the diagnostic effectiveness of human papillomavirus (HPV) methylation biomarkers for detection of cervical cancer. Methods: PubMed, Embase and Web of Science were searched. Nine articles focusing on HPV methylation for detection of precancerous and cancerous cervical lesions were included. The QUADAS-2 tool was used for quality assessment. The receiver operating characteristic (ROC) was the main diagnostic performance parameter extracted. Results: Of the nine articles included in this study, seven were of moderate quality and two were of high quality. A meta-analysis of the ROC for 27 HPV methylation biomarkers revealed an overall pooled ROC of 0.770 (95% CI: 0.720-0.819; I²: 98.4%; Q: 1537.4; p < 0.01). Four methylation biomarkers had strong diagnostic ability (ROC > 0.900), 17 were moderate (ROC: 0.7000-0.8999) and six were poor (ROC < 0.700). Conclusion: HPV methylation biomarkers hold significant promise as independent screening tests for the detection of cervical precancerous and cancerous lesions.

Epigenetic approaches for cervical neoplasia screening (Review)

Human papillomavirus (HPV) infection is the leading cause of cervical cancer. The Papanicolaou cytology test is the usually employed type of screening for this infection; however, its sensibility is limited. Only a small percentage of women infected with high-risk HPV develop cervical cancer with an array of genetic and epigenetic modifications. Thus, it is necessary to develop rapid, reproducible and minimally invasive technologies for screening. DNA methylation has gained attention as an alternative method for molecular diagnosis and prognosis in HPV infection. The aim of the present review was to highlight the potential of DNA methylation in cervical neoplasia screening for clinical applications. It was observed that the methylation human and viral genes was correlated with high-grade lesions and cancer. Methylation biomarkers have shown a good capacity to discriminate between high-grade lesions with a transformative potential and cervical cancer, being able to detect these modifications at an early stage. With further research, the epigenetic profiles and subtypes of the tumors could be elaborated, which would aid in therapy selection by opening avenues in personalized precision medicine. Response to therapy could also be evaluated through such methods and the accessibility of liquid biopsies would allow a constant monitoring of the patient's status without invasive sampling techniques.

Reduction in immune cell number and loss of 5hmC are associated with lesion grade in cervical carcinogenesis

Tumor genome methylation is closely related to tumor immunosuppression. In the present study, we evaluated the fluctuations in DNA methylation levels, and the numbers of infiltrating T cells and their cytokines in different-grade cervical lesions. A total of 154 human cervical specimens that included LSIL (43 cases), HSIL (48 cases), and cervical squamous cancer (63 cases) were used for this study. Immunohistochemistry for 5-hydroxymethylcytosine (5hmC) and T-cell-attracting chemokines was performed, and multiplex immunofluorescence labeling was used to identify different T-cell subtypes. We found that the proportions of samples that immunostained weakly or negatively for 5hmC were increased commensurately with elevations in the severity of cervical lesions. The expression of T-cell-attracting chemokines-including CXCL9, CXCL10, and CXCL11-was positively associated with 5hmC levels, and CXCL9 was the cytokine that was most pronounced. With the progression of cervical lesions, the numbers of total T cells, CTL, and NK cells in the cervical tissues all gradually decreased. During the occurrence and development of cervical squamous carcinoma, 5hmC was gradually lost, and immunosuppression occurred in precancerous cervical lesions.

Genetic and Epigenetic Variations of HPV52 in Cervical Precancer

The goal of this study was to identify human papillomavirus (HPV) type 52 genetic and epigenetic changes associated with high-grade cervical precancer and cancer. Patients were selected from the HPV Persistence and Progression (PaP) cohort, a cervical cancer screening program at Kaiser Permanente Northern California (KPNC). We performed a nested case-control study of 89 HPV52-positive women, including 50 cases with predominantly cervical intraepithelial neoplasia grade 3 (CIN3) and 39 controls without evidence of abnormalities. We conducted methylation analyses using Illumina sequencing and viral whole genome Sanger sequencing. Of the 24 CpG sites examined, increased methylation at CpG site 5615 in HPV52 L1 region was the most significantly associated with CIN3, with a difference in median methylation of 17.9% (odds ratio (OR) = 4.8, 95% confidence interval (CI) = 1.9–11.8) and an area under the curve of 0.73 (AUC; 95% CI = 0.62–0.83). Complete genomic sequencing of HPV52 isolates revealed associations between SNPs present in sublineage C2 and a higher risk of CIN3, with ORs ranging from 2.8 to 3.3. This study identified genetic and epigenetic HPV52 variants associated with high risk for cervical precancer, improving the potential for early diagnosis of cervical neoplasia caused by HPV52.

Human Papillomavirus and Cellular Pathways: Hits and Targets

The Human Papillomavirus (HPV) is the causative agent of different kinds of tumors, including cervical cancers, non-melanoma skin cancers, anogenital cancers, and head and neck cancers. Despite the vaccination campaigns implemented over the last decades, we are far from eradicating HPV-driven malignancies. Moreover, the lack of targeted therapies to tackle HPV-related tumors exacerbates this problem. Biomarkers for early detection of the pathology and more tailored therapeutic approaches are needed, and a complete understanding of HPV-driven tumorigenesis is essential to reach this goal. In this review, we overview the molecular pathways implicated in HPV infection and carcinogenesis, emphasizing the potential targets for new therapeutic strategies as well as new biomarkers.

Cervical cancer risk profiling: molecular biomarkers predicting the outcome of hrHPV infection

INTRODUCTION

Cervical cancer affects half a million women worldwide annually. Given the association between high-risk human papillomavirus (hrHPV) infection and carcinogenesis, hrHPV DNA testing became an essential diagnostic tool. However, hrHPV alone does not cause the disease, and, most importantly, many cervical lesions regress to normal in a year because of the host immune system. Hence, the low specificity of hrHPV DNA tests and their inability to predict the outcome of infections have triggered a further search for biomarkers.

AREAS COVERED

We evaluated the latest viral and cellular biomarkers validated for clinical use as primary screening or triage for cervical cancer and assessed their promise for prevention as well as potential use in the future. The literature search focused on effective biomarkers for different stages of the disease, aiming to determine their significance in predicting the outcome of hrHPV infections.

EXPERT OPINION

Biomarkers such as p16/Ki-67, hrHPV genotyping, hrHPV transcriptional status, and methylation patterns have demonstrated promising results. Their eventual implementation in the screening programs may support the prompt diagnosis of hrHPV infection and its progression to cancer. These biomarkers will help in making clinical management decisions on time, thus, saving the lives of hrHPV-infected women, particularly in developing countries.

Risk stratification of HPV 16 DNA methylation combined with E6 oncoprotein in cervical cancer screening: a 10-year prospective cohort study

Background

How to best triage human papillomavirus (HPV) positive women remains controversial in an era of HPV primary screening of cervical cancer. Here, we assessed the long-term risk stratification for triaging HPV 16 positive women by standalone HPV 16 methylation and combined with E6 oncoprotein.

Methods

 A total of 1742 women underwent screening with HPV DNA testing, cytology, and visual inspection with acetic acid (VIA) in 2005 and were followed for 10 years. Seventy-seven women with HPV 16 positivity determined by HPV genotyping test were examined via E6 oncoprotein detection and bisulfite pyrosequencing for quantitative methylation of L1 and LCR genes of HPV 16.

Results

The 10-year cumulative incidence rate (CIR) of cervical intraepithelial neoplasia grade 3 or severe (CIN3+) for HPV 16 positive women was 25.3% (95% CI 14.7–37.3%), which significantly increased in women with high methylation at six sites (CpG 5602, 6650, 7034, 7461, 31, and 37) and in women with positive E6 oncoprotein. A methylation panel based on the above six sites showed a competitive risk stratification compared to cytology (HR 11.5 vs. 8.1), with a higher 10-year CIR of CIN3+ in panel positives (57.2% vs 36.8%) and comparable low risk in panel negatives (5.7% vs 4.8%).The sensitivity and specificity for accumulative CIN3+ was 85.7% (95%CI 60.1–96.0%) and 78.4% (95%CI 62.8–88.6%) for a methylation panel and 57.1% (95%CI 32.6–78.6%) and 86.5% (95%CI 72.0–94.1%) for E6 oncoprotein. The AUC values of methylation standalone and the co-testing of methylation panel and E6 oncoprotein were around 0.80, comparable to 0.68 for cytology, 0.65 for viral load, and superior to 0.52 for VIA (p < 0.05).

Conclusions

Our findings indicated the promising use of HPV 16 methylation alone or combined with E6 oncoprotein for triaging HPV 16 positive women based on the long-term risk stratification ability.

Association between dense PAX1 promoter methylation and HPV16 infection in cervical squamous epithelial neoplasms of Xin Jiang Uyghur and Han women

DNA methylation is an epigenetic alteration that may lead to carcinogenesis by silencing key tumor suppressor genes. Hypermethylation of the paired box gene 1 (PAX1) promoter is important in cervical cancer development. Here, PAX1 methylation levels were compared between Uyghur and Han patients with cervical lesions. Data on PAX1 methylation in different cervical lesions were obtained from the Gene Expression Omnibus (GEO) database, whereas data on survival and PAX1 mRNA expression in invasive cervical cancer (ICC) were retrieved from the Cancer Genome Atlas (TCGA) database. MassARRAY spectrometry was used to detect methylation of 19 CpG sites in the promoter region of PAX1, whereas gene mass spectrograms were drawn by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. Human papillomavirus (HPV) 16 infection was detected by polymerase chain reaction. PAX1 methylation in high-grade squamous intraepithelial lesion (HSIL) and ICC was significantly higher than in normal tissues. PAX1 hypermethylation was associated with poor prognosis and reduced transcription. ICC-specific PAX1 promoter methylation involved distinct CpG sites in Uyghur and Han patients HPV16 infection in HSIL and ICC patient was significantly higher than in normal women (p < 0.05). Our study revealed a strong association between PAX1 methylation and the development of cervical cancer. Moreover, hypermethylation of distinct CpG sites may induce HSIL transformation into ICC in both Uyghur and Han patients. Our results suggest the existence of ethnic differences in the genetic susceptibility to cervical cancer. Finally, PAX1 methylation and HPV infection exhibited synergistic effects on cervical carcinogenesis.

Methylation of CpG 5962 in L1 of the human papillomavirus 16 genome as a potential predictive marker for viral persistence: A prospective large cohort study using cervical swab samples

Several studies have demonstrated that the viral genome can be methylated by the host cell during progression from persistent infection to cervical cancer. The aim of this study was to investigate whether methylation at a specific site could predict the development of viral persistence and whether viral load shows a correlation with specific methylation patterns. HPV16‐positive samples from women aged 20–29 years (n = 99) with a follow‐up time of 13 years, were included from a Danish cohort comprising 11 088 women. Viral load was measured by real‐time PCR and methylation status was determined for 39 CpG sites in the upstream regulatory region (URR), E6/E7, and L1 region of HPV16 by next‐generation sequencing. Participants were divided into two groups according to whether they were persistently (≥ 24 months) or transiently HPV16 infected. The general methylation status was significantly different between women with a persistent and women with a transient infection outcome (P = .025). One site located in L1 (nt. 5962) was statistically significantly (P = .00048) different in the methylation status after correction using the Holm‐Sidak method (alpha = 0.05). Correlation analyses of samples from HPV16 persistently infected women suggest that methylation is higher although viral load is lower. This study indicates that methylation at position 5962 of the HPV16 genome within the L1 gene might be a predictive marker for the development of a persistent HPV16 infection.

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.

Paired Box-1 (PAX1) Activates Multiple Phosphatases and Inhibits Kinase Cascades in Cervical Cancer

DNA methylation alteration, such as global hypomethylation and localized hypermethylation, within the promoters of tumor suppressor genes, is an important risk factor in cervical cancer. The potential use of DNA methylation detection, in cervical cancer screening or triage of mildly abnormal cytology, has recently been demonstrated. In particular, PAX1 DNA methylation testing was approved as an adjunct to cytology, in Taiwan, and is now undergoing registration trials in China. However, the function of PAX1 in cancer biology remains largely unknown. Here, we show that PAX1 inhibits malignant phenotypes upon oncogenic stress. Specifically, PAX1 expression inhibited the phosphorylation of multiple kinases, after challenges with oncogenic growth factors such as EGF and IL-6. Analogously, PAX1 activated a panel of phosphatases, including DUSP1, 5, and 6, and inhibited EGF/MAPK signaling. PAX1 also interacted with SET1B, increasing histone H3K4 methylation and DNA demethylation of numerous phosphatase-encoding genes. Furthermore, hypermethylated PAX1 associated with poor prognosis in cervical cancer. Taken together, this study reveals, for the first time, the functional relevance of PAX1 in cancer biology, and further supports the prospect of targeting multifold oncogenic kinase cascades, which jointly contribute to multiresistance, via epigenetic reactivation of PAX1.

Analysis of human papillomavirus 16 E6/E7 and L1 in the bronchial brushing cells of patients with squamous cell carcinoma of the lungs

A type of high-risk human papillomavirus (HPV), HPV16 takes part in lung carcinogenesis. E6 and E7 are the major oncoproteins of high-risk HPV, and L1 is the major capsid protein. In this study, we detected their mRNA expressions and analyzed their relationship in the bronchial brushing cells of 211 patients with malignant lesions (squamous cell carcinoma of the lungs) and benign lesions (pneumonia and tuberculosis) by quantitative real-time PCR. HPV16 E6, E7, and L1 mRNA expressions in the malignant group were statistically higher than in benign group (P<0.05), and their mRNA expressions in the squamous cell carcinoma of the lung group were statistically higher than in pneumonia group (P<0.05). There was a negative correlation between L1 and E6 expression in the squamous cell carcinoma of the lungs group (Spearman correlation coefficient r=-0.498, P=0.000). An ROC curve shows that the combination of L1 and E6 is a significant predictor for the diagnosis of squamous cell carcinoma of the lungs (AUC: 0.878; Sensitivity: 96.00%; Specificity: 77.91%), which could make up for the deficiency of cytologic testing. The combined detection of HPV16 E6 and L1 mRNA expressions in bronchial brushing cells by quantitative real-time PCR has a great significance for the diagnosis of squamous cell carcinoma of the lungs, providing new therapeutic targets for the clinical treatment of squamous cell carcinoma of the lungs.

The Progress of Methylation Regulation in Gene Expression of Cervical Cancer

Cervical cancer is one of the most common gynecological tumors in females, which is closely related to high-rate HPV infection. Methylation alteration is a type of epigenetic decoration that regulates the expression of genes without changing the DNA sequence, and it is essential for the progression of cervical cancer in pathogenesis while reflecting the prognosis and therapeutic sensitivity in clinical practice. Hydroxymethylation has been discovered in recent years, thus making 5-hmC, the more stable marker, attract more attention in the field of methylation research. As markers of methylation, 5-hmC and 5-mC together with 5-foC and 5-caC draw the outline of the reversible cycle, and 6-mA takes part in the methylation of RNA, especially mRNA. Furthermore, methylation modification participates in ncRNA regulation and histone decoration. In this review, we focus on recent advances in the understanding of methylation regulation in the process of cervical cancer, as well as HPV and CIN, to identify the significant impact on the prospect of overcoming cervical cancer.