Methylation and expression of miRNAs in precancerous lesions and cervical cancer with HPV16 infection

miR-218-5p, miR-124-3p and miR-23b-3p act synergistically to modulate the expression of NACC1, proliferation, and apoptosis in C-33A and CaSki cells

Background

In cervical cancer (CC), miR-218-5p, -124-3p, and -23b-3p act as tumor suppressors. These miRNAs have specific and common target genes that modulate apoptosis, proliferation, invasion, and migration; biological processes involved in cancer.

Methods

miR-218-5p, -124-3p, and -23b-3p mimics were transfected into C-33A and CaSki cells, and RT-qPCR was used to quantify the level of each miRNA and NACC1. Proliferation was assessed by BrdU and apoptosis by Annexin V/PI. In the TCGA and The Human Protein Atlas databases, the level of NACC1 mRNA and protein (putative target of the three miRNAs) was analyzed in CC and normal tissue. The relationship of NACC1 with the overall survival in CC was analyzed in GEPIA2. NACC1 mRNA and protein levels were higher in CC tissues compared with cervical tissue without injury.

Results

An increased expression of NACC1 was associated with lower overall survival in CC patients. The levels of miR-218-5p, -124-3p, and -23b-3p were lower, and NACC1 was higher in C-33A and CaSki cells compared to HaCaT cells. The increase of miR-218-5p, -124-3p, and -23b-3p induced a significant decrease in NACC1 mRNA. The transfection of the three miRNAs together caused more drastic changes in the level of NACC1, in the proliferation, and in the apoptosis with respect to the individual transfections of each miRNA.

Conclusion

The results indicate that miR-218-5p, -124-3p, and -23b-3p act synergistically to decrease NACC1 expression and proliferation while promoting apoptosis in C-33A and CaSki cells. The levels of NACC1, miR-218-5p, -124-3p, and -23b-3p may be a potential prognostic indicator in CC.

A microRNA Profile Regulates Inflammation-Related Signaling Pathways in Young Women with Locally Advanced Cervical Cancer

Cervical cancer (CC) remains among the most frequent cancers worldwide despite advances in screening and the development of vaccines against human papillomavirus (HPV), involved in virtually all cases of CC. In mid-income countries, a substantial proportion of the cases are diagnosed in advanced stages, and around 40% of them are diagnosed in women under 49 years, just below the global median age. This suggests that members of this age group share common risk factors, such as chronic inflammation. In this work, we studied samples from 46 patients below 45 years old, searching for a miRNA profile regulating cancer pathways. We found 615 differentially expressed miRNAs between tumor samples and healthy tissues. Through bioinformatic analysis, we found that several of them targeted elements of the JAK/STAT pathway and other inflammation-related pathways. We validated the interactions of miR-30a and miR-34c with JAK1 and STAT3, respectively, through dual-luciferase and expression assays in cervical carcinoma-derived cell lines. Finally, through knockdown experiments, we observed that these miRNAs decreased viability and promoted proliferation in HeLa cells. This work contributes to understanding the mechanisms through which HPV regulates inflammation, in addition to its canonical oncogenic function, and brings attention to the JAK/STAT signaling pathway as a possible diagnostic marker for CC patients younger than 45 years. To our knowledge to date, there has been no previous description of a panel of miRNAs or even ncRNAs in young women with locally advanced cervical cancer.

Prevalence and trends of cervical cancer screening among women in Fiji from 2014 to 2018

Introduction

Cervical cancer is the third most common cancer in women both in developed and developing countries. This study aimed to determine the prevalence of cervical cancer and the trends of cervical cancer screening among women who had cervical cancer screening in Suva, Fiji between 2014 and 2018.

Materials and method

This study applied a 5-year retrospective electronic chart review of data from all women attending the Women's Wellness Clinic (WWC) in Suva, Fiji. The women who were selected for this study and screened for cervical cancer were Fijian citizens above 18 years of age and were registered in 2014-2018. A data collection form was used to collect data. The data was analyzed using Statistical Package for Social Sciences (SPSS) version 24; p <0.05 % was considered as the level of significance.

Results

Among the 39,579 women who attended WWC for other family planning services, 12,074 women screened for cervical cancer with a prevalence of 30.5 %. The overall mean age for women screened for cervical cancer was 37.6 (SD ± 11.2). Two-thirds (76.4 %) of the women screened for cervical cancer were less than 46 years of age and 53.9 % were I-taukei. The number of women who came for Pap smear increased in 2015, however, a slight decline was observed in 2016 which was later improved to 35.1 % in 2018. Malignancy was more common in the age range of 42-49 respectively. In this study, women of 46 years and above had an OR of 0.51 (95 % CI: 0.36, 0.72), other ethnicity OR was 1.73 (95 % CI: 1.27, 2.35), and the Muslim religion OR recorded was 1.44 (95 % CI: 1.03, 2.01) which was comparatively considered a high-risk group. Women who are widowed 1.57 (95 % CI: 0.798, 3.11), single 1.29 (95 % CI: 0.87, 1.92) or divorced 1.08 (95 % CI: 0.59, 1.99), employed 1.01 (95 % CI: 0.83, 1.24) and are living in rural areas 1.19 (95 % CI: 0.82, 1.73) are also associated with higher odds of having abnormal results.

Conclusion

Cervical cancer is listed as the first and most common type of cancer in women which is noticeably increasing in Fiji. Even though cervical cancer screening has improved over the years, adequate surveillance systems and ongoing programs should be designed and implemented to increase awareness and monitor the trend of cervical cancer screening in order to reduce cervical cancer prevalence and mortality rates.

MiRNA in cervical cancer: Diagnosis to therapy: Systematic review

Cancers are one of the most public health problems worldwide. Among them, cervical cancer (CC) is the fourth most prevalent cancer with 604 000 new cases and 342 000 deaths. Mostly, it is associated with Human papillomavirus (HPV). It has been caused by the aggregation of genetic and epigenetic modifications in cervical epithelial cells. Although genetic mutations are given great attention for the carcinogenesis of CC, epigenetic changes have emerged as a hotspot area for CC biomarkers research with great implications for early diagnosis, prognosis, and treatment response prediction of the disease. Recently, there are several studies focused on miRNAs as biomarkers of cervical cancer. However, the precise function of miRNAs in the development of cervical cancer is not still completely understood, particularly when it comes to unconventional sampling materials like cervical mucus and plasma serum. Hence, this review article will give a summary of the miRNAs profiles that emerge at different stages of cervical cancer progression and their downstream effects on target genes and associated signaling pathways. Finally, these results may provide insight into the use of miRNAs as biomarkers for the prediction or diagnosis of cervical cancer or the development of miRNA-based therapeutics against cervical cancer.

Multifaceted role of microRNAs in gastric cancer stem cells: Mechanisms and potential biomarkers

MicroRNAs (miRNAs) have received much attention in the past decade as potential key epigenomic regulators of tumors and cancer stem cells (CSCs). The abnormal expression of miRNAs is responsible for different phenotypes of gastric cancer stem cells (GCSCs). Some specific miRNAs could be used as promising biomarkers and therapeutic targets for the identification of GCSCs. This review summarizes the coding process and biological functions of miRNAs and demonstrates their role and efficacy in gastric cancer (GC) metastasis, drug resistance, and apoptosis, especially in the regulatory mechanism of GCSCs. It shows that the overexpression of onco-miRNAs and silencing of tumor-suppressor miRNAs can play a role in promoting or inhibiting tumor metastasis, apart from the initial formation of GC. It also discusses the epigenetic regulation and potential clinical applications of miRNAs as well as the role of CSCs in the pathogenesis of GC. We believe that this review may help in designing novel therapeutic approaches for GC.

Application of Protein-Protein Interaction Network Analysis in Order to Identify Cervical Cancer miRNA and mRNA Biomarkers

Cervical cancer (CC) is one of the world's most common and severe cancers. This cancer includes two histological types: squamous cell carcinoma (SCC) and adenocarcinoma (ADC). The current study aims at identifying novel potential candidate mRNA and miRNA biomarkers for SCC based on a protein-protein interaction (PPI) and miRNA-mRNA network analysis. The current project utilized a transcriptome profile for normal and SCC samples. First, the PPI network was constructed for the 1335 DEGs, and then, a significant gene module was extracted from the PPI network. Next, a list of miRNAs targeting module's genes was collected from the experimentally validated databases, and a miRNA-mRNA regulatory network was formed. After network analysis, four driver genes were selected from the module's genes including MCM2, MCM10, POLA1, and TONSL and introduced as potential candidate biomarkers for SCC. In addition, two hub miRNAs, including miR-193b-3p and miR-615-3p, were selected from the miRNA-mRNA regulatory network and reported as possible candidate biomarkers. In summary, six potential candidate RNA-based biomarkers consist of four genes containing MCM2, MCM10, POLA1, and TONSL, and two miRNAs containing miR-193b-3p and miR-615-3p are opposed as potential candidate biomarkers for CC.

miR-23b-3p, miR-124-3p and miR-218-5p Synergistic or Additive Effects on Cellular Processes That Modulate Cervical Cancer Progression? A Molecular Balance That Needs Attention

In cervical cancer (CC), miR-23b-3p, miR-124-3p, and miR-218-5p have been found to act as tumor suppressors by regulating cellular processes related to progression and metastasis. The objective of the present review is to provide an update on the experimental evidence about the role of miR-23b-3p, miR-124-3p, and miR-218-5p in the regulation of CC progression. Additionally, we present the results of a bioinformatic analysis that suggest that these miRNAs have a somewhat redundant role in the same cellular processes that may result in a synergistic effect to promote CC progression. The results indicate that specific and common target genes for miR-23b-3p, miR-124-3p, and miR-218-5p regulate proliferation, migration, apoptosis, and angiogenesis, all processes that are related to CC maintenance and progression. Furthermore, several target genes may regulate cancer-related signaling pathways. We found that a total of 271 proteins encoded by the target mRNAs of miR-23b-3p, miR-124-3p, or miR-218-5p interact to regulate the cellular processes previously mentioned, and some of these proteins are regulated by HPV-16 E7. Taken together, information analysis indicates that miR-23b-3p, miR-124-3p, and miR-218-5p may potentiate their effects to modulate the cellular processes related to the progression and maintenance of CC with and without HPV-16 involvement.

miR-218-5p/RUNX2 Axis Positively Regulates Proliferation and Is Associated with Poor Prognosis in Cervical Cancer

The overexpression of miR-218-5p in cervical cancer (CC) cell lines decreases migration, invasion and proliferation. The objective was to identify target genes of miR-218-5p and the signaling pathways and cellular processes that they regulate. The relationship between the expression of miR-218-5p and RUNX2 and overall survival in CC as well as the effect of the exogenous overexpression of miR-218-5p on the level of RUNX2 were analyzed. The target gene prediction of miR-218-5p was performed in TargetScan, miRTarBase and miRDB. Predicted target genes were subjected to gene ontology (GO) and pathway enrichment analysis using the Kyoto Encyclopaedia of Genes and Genomes (KEGG). The miR-218-5p mimetic was transfected into C-33A and CaSki cells, and the miR-218-5p and RUNX2 levels were determined by RT–qPCR. Of the 118 predicted targets for miR-218-5p, 86 are involved in protein binding, and 10, including RUNX2, are involved in the upregulation of proliferation. Low miR-218-5p expression and a high level of RUNX2 are related to poor prognosis in CC. miR-218-5p overexpression is related to decreased RUNX2 expression in C-33A and CaSki cells. miR-218-5p may regulate RUNX2, and both molecules may be prognostic markers in CC.

DNA methylation of miR-138 regulates cell proliferation and EMT in cervical cancer by targeting EZH2

BACKGROUND

Emerging evidence has identified miR-138 as a tumor suppressor that can suppress the proliferation of various cancers. Meanwhile, the cause of abnormal miR-138 expression in cervical cancer remains uncertain. This study clarified the mechanism by which miR-138 regulates proliferation, invasion, metastasis, and EMT in cervical cancer cells.

RESULTS

miR-138 expression in human cervical cancer and adjacent normal tissue was measured using qPCR. SiHa and C33A cells were used to determine the function of miR-138 via miR-138 mimic or inhibitor transfection, followed by wound healing, Cell Counting Kit-8, flow cytometry, and Transwell assays. Epithelial and mesenchymal marker expression was analyzed using Western blotting. DNA methylation in the miR-138 promoter was examined using bisulfite sequencing PCR. The downstream target genes of miR-138 were identified via bioinformatics analysis and luciferase reporter assays. A tumor xenograft model was employed to validate DNA methylation-induced miR-138 downregulation and tumor growth inhibition in cervical cancer in vivo. miR-138 levels were significantly lower in cervical cancer tissues than in adjacent control tissues. Furthermore, lower miR-138 expression and higher CpG methylation in the miR-138 promoter were identified in lymph node-positive metastatic cervical cancer tumors versus that in non-metastatic tumor tissues. Upon miR-138 overexpression, cell proliferation, metastasis, invasion, and EMT were suppressed. miR-138 agomir transfection and demethylating drug treatment significantly inhibited cervical tumor growth and EMT in tumor xenograft models. DNA methylation inhibited miR-138 transcription, and enhancer of zeste homolog 2 (EZH2) downregulation mediated the tumor suppressor function of miR-138 in cervical cancer.

CONCLUSION

We demonstrated that miR-138 suppresses tumor progression by targeting EZH2 in cervical cancer and uncovered the role of DNA methylation in the miR-138 promoter in its downregulation. These findings demonstrated the potential of miR-138 to predict disease metastasis and/or function as a therapeutic target in cervical cancer.

TRF2 cooperates with CTCF for controlling the oncomiR-193b-3p in colorectal cancer

The Telomeric Repeat binding Factor 2 (TRF2), a key protein involved in telomere integrity, is over-expressed in several human cancers and promotes tumor formation and progression. Recently, TRF2 has been also found outside telomeres where it can affect gene expression. Here we provide evidence that TRF2 is able to modulate the expression of microRNAs (miRNAs), small non-coding RNAs altered in human tumors. Among the miRNAs regulated by TRF2, we focused on miR-193b-3p, an oncomiRNA that positively correlates with TRF2 expression in human colorectal cancer patients from The Cancer Genome Atlas dataset. At the mechanistic level, the control of miR-193b-3p expression requires the cooperative activity between TRF2 and the chromatin organization factor CTCF. We found that CTCF physically interacts with TRF2, thus driving the proper positioning of TRF2 on a binding site located upstream the miR-193b-3p host-gene. The binding of TRF2 on the identified region is necessary for promoting the expression of miR-193b3p which, in turn, inhibits the translation of the onco-suppressive methyltransferase SUV39H1 and promotes tumor cell proliferation. The translational relevance of the oncogenic properties of miR-193b-3p was confirmed in patients, in whom the association between TRF2 and miR-193b-3p has a prognostic value.

Role of microRNAs (MiRNAs) as biomarkers of cervical carcinogenesis: a systematic review

We performed a systematic review to identify the role of microRNAs (miRNAs) as biomarkers in the progression of cervical precancerous lesions. A comprehensive search of the Cochrane Controlled Register of Trials, PubMed, ScienceDirect, and Embase databases was performed for articles published between January 2010 and June 2020. The following Medical Subject Headings (MeSH) terms were searched: “microRNA” and “cervical” and “lesion.” All study designs that aimed to evaluate the correlation of miRNA expression with different precancerous cervical staging and/ or cervical cancer were included, except for case reports and case series. Approximately 82 individual miRNAs were found to be significant in differentiating the stages of cervical carcinogenesis. Among the miRNAs, miR-21 is the most prevalent, and it is consistently upregulated progressively from normal cervical to worsening cervical lesion stages in both cell and serum samples. miR-205 has been shown to have a higher specificity than human papilloma virus testing in predicting the absence of high-grade squamous intraepithelial lesions (HSILs) in exfoliated cell samples. The tumor suppressor miRNAs miR-34, let-7, miR-203 miR-29, and miR-375 were significantly downregulated in low-grade squamous intraepithelial lesions, HSILs, and cervical cancer. We found significant dysregulated miRNAs in cervical carcinogenesis with their dynamic expression changes and ability to detect viral persistency, risk prediction of low-grade lesions (cervical intraepithelial neoplasia [CIN] 2) to high-grade lesions (CIN 3), and progression of CIN 3 to cancer. Their ability to discriminate HSILs from non-dysplastic lesions has potential implications in early diagnosis and reducing overtreatment of otherwise regressive early preinvasive lesions.

miRNAs as biomarkers for early cancer detection and their application in the development of new diagnostic tools

Over the last decades, microRNAs (miRNAs) have emerged as important molecules associated with the regulation of gene expression in humans and other organisms, expanding the strategies available to diagnose and handle several diseases. This paper presents a systematic review of literature of miRNAs related to cancer development and explores the main techniques used to quantify these molecules and their limitations as screening strategy. The bibliographic research was conducted using the online databases, PubMed, Google Scholar, Web of Science, and Science Direct searching the terms "microRNA detection", "miRNA detection", "miRNA and prostate cancer", "miRNA and cervical cancer", "miRNA and cervix cancer", "miRNA and breast cancer", and "miRNA and early cancer diagnosis". Along the systematic review over 26,000 published papers were reported, and 252 papers were returned after applying the inclusion and exclusion criteria, which were considered during this review. The aim of this study is to identify potential miRNAs related to cancer development that may be useful for early cancer diagnosis, notably in the breast, prostate, and cervical cancers. In addition, we suggest a preliminary top 20 miRNA panel according to their relevance during the respective cancer development. Considering the progressive number of new cancer cases every year worldwide, the development of new diagnostic tools is critical to refine the accuracy of screening tests, improving the life expectancy and allowing a better prognosis for the affected patients.

Circulating miR-15b, miR-34a and miR-218 as promising novel early low-invasive biomarkers of cervical carcinogenesis

Circulating biological markers, such as miRNAs, hold the greatest possibilities to complement tissue biopsy and clinical diagnostic tests. The objective of this study was to evaluate the relative abundance of three circulating miRNAs in serum from 17 HPV16-positive patients with early cervical lesions known as Low-Grade Squamous Intraepithelial Lesions (LSILs). The expression of circulating microRNAs miR-15b, miR-34a and miR-218 in patients with LSILs was compared to 23 HPV-negative individuals showing normal cervical epithelium (healthy women) and 23 Squamous Cell Carcinoma (SCC) samples. The expression levels of miR-15b remained unchanged while those of miRNAs 34a and 218 were relatively high in serum obtained from LSIL patients in comparison with healthy women (results were statistically significant with a p of < 0.01 or < 0.001). According to previous findings, miR-15b was overexpressed and miRNAs 34a and 218 were underexpressed in serum from SCC patients. Additionally, the mRNA expression levels of some selected gene targets were determined [Cyclin D1 (CCND1), Cyclin E1 (CCNE1), B-cell lymphoma 2 (Bcl-2) and MutS homolog 2 (MSH-2)]. All serum results correlated with tissue samples from the same patients. We propose that circulating microRNAs can be valuable as molecular markers for the early follow-up of cervical carcinogenesis risk.

MicroRNA-Based Fingerprinting of Cervical Lesions and Cancer

The regulatory functions of microRNA (miRNA) are involved in all processes contributing to carcinogenesis and response to viral infections. Cervical cancer in most cases is caused by the persistence of high-risk human papillomavirus (HR-HPV) infection. While oncogenic human papillomaviruses induce aberrant expression of many cellular miRNAs, this dysregulation could be harnessed as a marker in early diagnosis of HR-HPV infection, cervical squamous intraepithelial lesions, and cancer. In recent years, growing data indicate that miRNAs show specific patterns at various stages of cervical pathology. The aim of this review is to systematize current reports on miRNA capacity that can be utilized in personalized diagnostics of cervical precancerous and cancerous lesions. The analysis of the resources available in online databases (National Center for Biotechnology Information—NCBI, PubMed, ScienceDirect, Scopus) was performed. To date, no standardized diagnostic algorithm using the miRNA pattern in cervical pathology has been defined. However, the high sensitivity and specificity of the reported assays gives hope for the development of non-invasive diagnostic tests that take into account the heterogeneity of tumor-related changes. Due to this variability resulting in difficult to predict clinical outcomes, precise molecular tools are needed to improve the diagnostic and therapeutic process.

Regulatory Mechanisms of Epigenetic miRNA Relationships in Human Cancer and Potential as Therapeutic Targets

Simple Summary

By the virtue of targeting multiple genes, a microRNA (miRNA) can infer variable consequences on tumorigenesis by appearing as both a tumour suppressor and oncogene. miRNAs can regulate gene expression by modulating genome-wide epigenetic status of genes that are involved in various cancers. These miRNAs perform direct inhibition of key mediators of the epigenetic machinery, such as DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) genes. Along with miRNAs gene expression, similar to other protein-coding genes, miRNAs are also controlled by epigenetic mechanisms. Overall, this reciprocal interaction between the miRNAs and the epigenetic architecture is significantly implicated in the aberrant expression of miRNAs detected in various human cancers. Comprehensive knowledge of the miRNA-epigenetic dynamics in cancer is essential for the discovery of novel anticancer therapeutics.

Abstract

Initiation and progression of cancer are under both genetic and epigenetic regulation. Epigenetic modifications including alterations in DNA methylation, RNA and histone modifications can lead to microRNA (miRNA) gene dysregulation and malignant cellular transformation and are hereditary and reversible. miRNAs are small non-coding RNAs which regulate the expression of specific target genes through degradation or inhibition of translation of the target mRNA. miRNAs can target epigenetic modifier enzymes involved in epigenetic modulation, establishing a trilateral regulatory “epi–miR–epi” feedback circuit. The intricate association between miRNAs and the epigenetic architecture is an important feature through which to monitor gene expression profiles in cancer. This review summarises the involvement of epigenetically regulated miRNAs and miRNA-mediated epigenetic modulations in various cancers. In addition, the application of bioinformatics tools to study these networks and the use of therapeutic miRNAs for the treatment of cancer are also reviewed. A comprehensive interpretation of these mechanisms and the interwoven bond between miRNAs and epigenetics is crucial for understanding how the human epigenome is maintained, how aberrant miRNA expression can contribute to tumorigenesis and how knowledge of these factors can be translated into diagnostic and therapeutic tool development.

Small RNAs, Big Diseases

The past two decades have seen extensive research done to pinpoint the role of microRNAs (miRNAs) that have led to discovering thousands of miRNAs in humans. It is not, therefore, surprising to see many of them implicated in a number of common as well as rare human diseases. In this review article, we summarize the progress in our understanding of miRNA-related research in conjunction with different types of cancers and neurodegenerative diseases, as well as their potential in generating more reliable diagnostic and therapeutic approaches.

Potential microRNA panel for the diagnosis and prediction of overall survival of hepatocellular carcinoma with hepatitis B virus infection

BACKGROUND

In hepatocellular carcinoma (HCC), abnormal expression of multiple microRNAs (miRNAs) has been shown to be involved in the malignant biological behavior of liver cancer. The vast majority of liver cancer cases in China are closely related to hepatitis B virus (HBV) infection, but there are few studies on the changes of miRNA expression in the progression from HBV infection to hepatoma.

AIM

To explore the role of miRNAs in the progression of HBV infection to cirrhosis and even to liver cancer.

METHODS

We screened differentially expressed miRNAs in 40 HBV cirrhosis, 40 normal and 15 HCC tissues by using a TaqMan Low Density Array and real time quantitative polymerase chain reaction. To evaluate the power of the selected miRNAs to predict disease, we calculated the area under the receiver-operating-characteristic curves. The overall survival of HBV cirrhosis patients was analyzed via Kaplan-Meier analysis.

RESULTS

The levels of miR-375, miR-122 and miR-143 were significantly lower in HBV cirrhosis tissues, while miR-224 was significantly higher than in the controls (P < 0.0001). The area under the curves of the receiver-operating-characteristic curve for the 4-miRNA panel was 0.991 (95%CI: 0.974-1). Patients with a lower expression level of miR-224 or higher expression levels of miR-375, miR-122 and miR-143 had longer overall survival.

CONCLUSION

The four miRNAs (miR-375, miR-122, miR-143 and miR-224) may be helpful for early diagnosis of HBV infection, HBV cirrhosis, and prediction of its overall survival.

Study on the correlation between hTREC and HPV load and cervical CINI/II/III lesions and cervical cancer

Objective

To investigate the correlation between hTREC and human papillomavirus (HPV) load and cervical intraepithelial neoplasia (CIN) grade II/III lesions and cervical cancer.

Methods

A total of 135 patients with cervical lesions of different degrees admitted to our hospital from January 2016 to February 2017 were selected, including CIN I/III 65 cases, grade III 39 cases, and cervical cancer 31 cases. The expression of hTERC gene was detected by fluorescence in situ hybridization (FISH) in three groups, and the HPV load was detected by second‐generation hybridization capture (HC II) method, and its relationship with cervical lesion grade was analyzed. Department.

Results

The positive expression rate of hTERC gene amplification was cervical cancer > CIN I/II lesion > CIN III lesion; the positive expression rate of HPV was cervical cancer > CIN I/II lesion > CIN III lesion. After treatment, the positive rate of hTERC gene amplification and HPV expression decreased significantly within 1 year (P < .05). Spearman's analysis showed that the degree of cervical lesion was positively correlated with hTREC and HPV load (P < .05).

Conclusion

hTREC and HPV are closely related to the occurrence and development of cervical precancerous lesions and cervical cancer. The abnormal amplification of hTERC gene increases with the grade of cervical lesions. Both of them can be used as auxiliary indicators for early screening, treatment, and prognosis of cervical cancer.

Human Papillomavirus Infections, Cervical Cancer and MicroRNAs: An Overview and Implications for Public Health

Human Papillomavirus (HPV) is among the most common sexually transmitted infections in both females and males across the world that generally do not cause symptoms and are characterized by high rates of clearance. Persistent infections due at least to twelve well-recognized High-Risk (HR) or oncogenic genotypes, although less frequent, can occur, leading to diseases and malignancies, principally cervical cancer. Three vaccination strategies are currently available for preventing certain HR HPVs-associated diseases, infections due to HPV6 and HPV11 low-risk types, as well as for providing cross-protection against non-vaccine genotypes. Nevertheless, the limited vaccine coverage hampers reducing the burden of HPV-related diseases globally. For HR HPV types, especially HPV16 and HPV18, the E6 and E7 oncoproteins are needed for cancer development. As for other tumors, even in cervical cancer, non-coding microRNAs (miRNAs) are involved in posttranscriptional regulation, resulting in aberrant expression profiles. In this study, we provide a summary of the epidemiological background for HPV occurrence and available immunization programs. In addition, we present an overview of the most relevant evidence of miRNAs deregulation in cervical cancer, underlining that targeting these biomolecules could lead to wide translational perspectives, allowing better diagnosis, prognosis and therapeutics, and with valuable applications in the field of prevention. The literature on this topic is rapidly growing, but advanced investigations are required to achieve more consistent findings on the up-regulated and down-regulated miRNAs in cervical carcinogenesis. Because the expression of miRNAs is heterogeneously reported, it may be valuable to assess factors and risks related to individual susceptibility.

miR‑218 functions as a tumor suppressor gene in cervical cancer

Previous microRNA (miR) microarray analysis revealed that miR‑218 is downregulated in cervical cancer tissues. The present study aimed to further evaluate the expression of miR‑218 in cervical cancer specimens, determine the association between its expression with disease progression, and investigate the roles of miR‑218 in cervical cancer cells. Tissue specimens were obtained from 80 patients with cervical squamous cell carcinoma, 30 patients with high‑grade cervical intraepithelial neoplasia [(CIN) II/III] and 15 patients with low‑grade CIN (CINI); in addition, 60 plasma samples were obtained from patients with cervical cancer, and 15 normal cervical tissue specimens and 30 plasma samples were obtained from healthy women. These samples were used for analysis of miR‑218 expression via reverse transcription‑-quantitative PCR. In addition, tumor cells were transfected with miR‑218 mimics, human papillomavirus (HPV)16 E6/E7 small interfering RNA, or their respective negative controls to determine the viability, colony formation, migration and invasion of cells using MTT, colony formation, wound healing and Transwell assays, respectively. Target genes of miR‑218 were bioinformatically predicted and analyzed using Gene Ontology (GO) terms. The results revealed that miR‑218 was downregulated in the tumor tissues and plasma of patients with cervical cancer, with expression associated with the advanced clinicopathological characteristics of patients, including HPV positivity, tumor size, blood vessel invasion and lymph node metastasis. Furthermore, miR‑218 overexpression reduced tumor cell viability and xenograft growth, and suppressed tumor cell migration and invasion. HPV was detected in 75% of the 80 patients with cervical cancer, and HPV positivity was inversely associated with miR‑218 expression. In addition, bioinformatics analysis predicted that roundabout guidance receptor 1 (ROBO1) was a target gene of miR‑218; miR‑218 overexpression significantly reduced ROBO1 levels. Furthermore, GO analysis revealed that ROBO1 was involved in regulating cell proliferation, adhesion and migration, and the cell cycle. In conclusion, the findings of the present study suggested that miR‑218 may possess antitumor activities in cervical cancer.

Transregulation of microRNA miR-21 promoter by AP-1 transcription factor in cervical cancer cells

BACKGROUND

Gene expression profiles have demonstrated that miR-21 expression is altered in almost all types of cancers and it has been classified as an oncogenic microRNA. Persistent HPV infection is the main etiologic agent in cervical cancer and induces genetic instability, including disruption of microRNA gene expression. In the present study, we analyzed the underlying mechanism of how AP-1 transcription factor can active miR-21 gene expression in cervical cancer cells.

METHODS

To identify that c-Fos and c-Jun regulate the expression of miR-21 we performed RT-qPCR and western blot assays. We analyzed the interaction of AP-1 with miR-21 promoter by EMSA and ChIP assays and determined the mechanism of its regulation by reporter construct plasmids. We identified the nuclear translocation of c-Fos and c-Jun by immunofluorescence microscopy assays.

RESULTS

We demonstrated that c-Fos and c-Jun proteins are expressed and regulate the expression of miR-21 in cervical cancer cells. DNA sequence analysis revealed the presence of AP-1 DNA-binding sites in the human miR-21 promoter region. EMSA analyses confirmed the interactions of the miR-21 upstream transcription factor AP-1. ChIP assays further showed the binding of c-Fos to AP-1 sequences from the miR-21 core promoter in vivo. Functional analysis of AP-1 sequences of miR-21 in reporter plasmids demonstrated that these sequences increase the miR-21 promoter activation.

CONCLUSIONS

Our findings suggest a physical interaction and functional cooperation between AP-1 transcription factor in the miR-21 promoter and may explain the effect of AP-1 on miR-21 gene expression in cervical cancer cells.

Methylation-associated miR-193b silencing activates master drivers of aggressive prostate cancer

Epigenetic silencing of miRNA is a primary mechanism of aberrant miRNA expression in cancer, and hypermethylation of miRNA promoters has been reported to contribute to prostate cancer initiation and progression. Recent data have shown that the miR‐193b promoter is hypermethylated in prostate cancer compared with normal tissue, but studies assessing its functional significance have not been performed. We aimed to elucidate the function of miR‐193b and identify its critical targets in prostate cancer. We observed an inverse correlation between miR‐193b level and methylation of its promoter in The Cancer Genome Atlas (TCGA) cohort. Overexpression of miR‐193b in prostate cancer cell lines inhibited invasion and induced apoptosis. We found that a majority of the top 150 genes downregulated when miR‐193b was overexpressed in liposarcoma are overexpressed in metastatic prostate cancer and that 41 miR‐193b target genes overlapped with the 86 genes in the aggressive prostate cancer subtype 1 (PCS1) signature. Overexpression of miR‐193b led to the inhibition of the majority of the 41 genes in prostate cancer cell lines. High expression of the 41 genes was correlated with recurrence of prostate cancer. Knockdown of miR‐193b targets FOXM1 and RRM2 in prostate cancer cells phenocopied overexpression of miR‐193b. Dual treatment with DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors decreased miR‐193b promoter methylation and restored inhibition of FOXM1 and RRM2. Our data suggest that silencing of miR‐193b through promoter methylation may release the inhibition of PCS1 genes, contributing to prostate cancer progression and suggesting a possible therapeutic strategy for aggressive prostate cancer.

Characterizing methylation regulated miRNA in carcinoma of the human uterine cervix

Gene regulatory mechanisms determine the multistep carcinogenesis process. Two aspects of epigenetics are microRNA (miRNAs) and DNA methylation that regulate distinct biological mechanisms such as metastasis, apoptosis cell proliferation and induction of senescence. Although critical, the interplay between these two epigenetic mechanisms is yet to be completely understood, particularly in cervical cancer. To study the DNA methylation regulation of miRNAs and its potential role in cervical cancer, we investigated the differential methylation pattern of two candidate miRNAs (miR-375 and miR-196a-1) during cervical cancer progression against normal cervical epithelium (NCE) by bisulfite DNA sequencing. miR-375 and miR-196a-1 were hypermethylated in Squamous Cell Carcinoma (SCC) against NCE and Cervical Intra-Epithelial Neoplasia (CIN) (p < 0.05). Treatment with demethylating agent reactivated the miR-375 and miR-196a-1 expression in SiHa, HeLa and CaSki cells. In vitro artificial methylation by M.SssI followed by dual luciferase assay confirmed miR-375 and miR-196a-1 as methylation regulated miRNAs (P < 0.05). miR-375 and miR-196a-1 expression levels were negatively correlated with methylation levels in clinical specimens. We further identified Replication Factor C Subunit 3 (RFC3) and High Mobility Group AT-Hook 1 (HMGA1) as targets of miR-375 and miR-196a-1 respectively by dual luciferase reporter assay. Our analysis indicates that miR-375 and miR-196a-1 are DNA methylation regulated miRNAs whose deregulation may facilitate pathophysiology of cervical cancer.

Cervical cancer subtypes harbouring integrated and/or episomal HPV16 portray distinct molecular phenotypes based on transcriptome profiling of mRNAs and miRNAs

Heterogeneity in cervical cancers (CaCx) in terms of HPV16 physical status prompted us to investigate the mRNA and miRNA signatures among the different categories of CaCx samples. We performed microarray-based mRNA expression profiling and quantitative real-time PCR-based expression analysis of some prioritised miRNAs implicated in cancer-related pathways among various categories of cervical samples. Such samples included HPV16-positive CaCx cases that harboured either purely integrated HPV16 genomes (integrated) and those that harboured episomal viral genomes, either pure or concomitant with integrated viral genomes (episomal), which were compared with normal cervical samples that were either HPV negative or positive for HPV16. The mRNA expression profile differed characteristically between integrated and episomal CaCx cases for enriched biological pathways. miRNA expression profiles also differed among CaCx cases compared with controls (upregulation—miR-21, miR-16, miR-205, miR-323; downregulation—miR-143, miR-196b, miR-203, miR-34a; progressive upregulation—miR-21 and progressive downregulation—miR-143, miR-34a, miR-196b and miR-203) in the order of HPV-negative controls, HPV16-positive non-malignant samples and HPV16-positive CaCx cases. miR-200a was upregulated in HPV16-positive cervical tissues irrespective of histopathological status. Expression of majority of the predicted target genes was negatively correlated with their corresponding miRNAs, irrespective of the CaCx subtypes. E7 mRNA expression correlated positively with miR-323 expression among episomal cases and miR-203, among integrated cases. miR-181c expression was downregulated only among the episomal CaCx cases and negatively correlated with protein coding transcript of the proliferative target gene, CKS1B of the significantly enriched “G2/M DNA Damage Checkpoint Regulation” pathway among CaCx cases. Thus, the two CaCx subtypes are distinct entities at the molecular level, which could be differentially targeted for therapy. In fact, availability of a small molecule inhibitor of CKS1B, suggests that drugging CKS1B could be a potential avenue of treating the large majority of CaCx cases harbouring episomal HPV16.

MicroRNAs in brain development and cerebrovascular pathophysiology

MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs with 21-25 nucleotides in length and play an important role in regulating gene expression at the posttranscriptional level via base-paring with complementary sequences of the 3'-untranslated region of the target gene mRNA, leading to either transcript degradation or translation inhibition. Brain-enriched miRNAs act as versatile regulators of brain development and function, including neural lineage and subtype determination, neurogenesis, synapse formation and plasticity, neural stem cell proliferation and differentiation, and responses to insults. Herein, we summarize the current knowledge regarding the role of miRNAs in brain development and cerebrovascular pathophysiology. We review recent progress of the miRNA-based mechanisms in neuronal and cerebrovascular development as well as their role in hypoxic-ischemic brain injury. These findings hold great promise, not just for deeper understanding of basic brain biology but also for building new therapeutic strategies for prevention and treatment of pathologies such as cerebral ischemia.

miR-193: A new weapon against cancer

microRNAs (miRNAs) are known as a large group of short noncoding RNAs, which structurally consist of 19-22 nucleotides in length and functionally act as one of the main regulators of gene expression in important biological and physiological contexts like cell growth, apoptosis, proliferation, differentiation, movement (cell motility), and angiogenesis as well as disease formation and progression importantly in cancer cell invasion, migration, and metastasis. Among these notable tiny molecules, many studies recently presented the important role of the miR-193 family comprising miR-193a-3p, miR-193a-5p, miR-193b-3p, and miR-193b-5p in health and disease biological processes by interaction with special targeting and signaling, which mainly contribute as a tumor suppressor. Therefore, in the present paper, we review the functional role of this miRNA family in both health and disease conditions focusing on various tumor developments, diagnoses, prognoses, and treatment.

Correlative analysis of the expression of IL-10 and Ki-67 in human cervical cancer and cervical intraepithelial neoplasias and human papillomavirus infection

This study investigated the expression of IL-10 and Ki-67 in human cervical cancer and cervical intraepithelial neoplasia (CIN) and the correlation with human papillomavirus infection. A total of 110 patients with cervical lesions undergoing surgical treatment in Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine from 2016 to 2017 were selected. Those patients included 36 cases of cervical cancer and 74 cases of CIN. At the same time, 30 cases of chronic cervicitis were selected as the control group. RT-qPCR was used to detect the expression of IL-10 and Ki-67 in cervical tissue. PCR was used to detect HPV infection in cervical tissue. The expression levels of IL-10 and Ki-67 in the cervical cancer and CIN groups were higher than those in the control group. Moreover, the expression levels of IL-10 and Ki-67 in the cervical cancer and CIN II-III groups were higher than those in the CIN I group (P<0.05). In addition, the expression levels of IL-10 and Ki-67 in the cervical cancer group were significantly higher than those in the CIN II-III group. Furthermore, the expression levels of IL-10 and Ki-67 were positively correlated with HPV infection (r=0.783 or 0.712, P<0.05). Finally, the expression levels of IL-10 and Ki-67, and HPV infection in the cervical lesions studied were significantly different. Therefore, combined detection of IL-10, Ki-67 and HPV infection can improve the diagnosis of CIN and early cervical cancer.

MicroRNAs as markers of progression in cervical cancer: a systematic review

BACKGROUND

Invasive cervical cancer (ICC) is caused by high-risk human papillomavirus types (HR-HPVs) and is usually preceded by a long phase of intraepithelial neoplasia (CIN). Before invasion, (epi) genetic changes, potentially applicable as molecular markers within cervical screening, occur in HPV host cells. Epigenetic alterations, such as dysregulation of microRNA (miRNA) expression, are frequently observed in ICC. The mechanisms and role of miRNA dysregulation in cervical carcinogenesis are still largely unknown.

METHODS

We provide an overview of the studies investigating miRNA expression in relation to ICC progression, highlighting their common outcomes and their weaknesses/strengths. To achieve this, we systematically searched through Pubmed database all articles between January 2010 and December 2017.

RESULTS

From the 24 studies retrieved, miR-29a and miR-21 are the most frequently down- and up-regulated in ICC progression, respectively. Microarray-based studies show a small overlap, with miR-10a, miR-20b, miR-9, miR-16 and miR-106 found repeatedly dysregulated. miR-34a, miR-125 and miR-375 were also found dysregulated in cervical exfoliated cells in relation to cancer progression.

CONCLUSIONS

The pivotal role of miRNAs in ICC progression and initial development is becoming more and more relevant. Available studies are essentially based on convenience material, entailing possible selection bias, and frequently of small size: all these points still represent a limitation to a wide comprehension of miRNAs relevant for ICC. The targeted approach instead of a genome-wide investigation still precludes the identification of all the relevant miRNAs in the process. The implementation of deep sequencing on large scale population-based studies will help to discover and validate the relation between altered miRNA expression and CC progression for the identification of biomarkers. Optimally, once explored on a miRNome scale, small specific miRNA signatures maybe used in the context of screening.

Up-regulation of miR-20a by HPV16 E6 exerts growth-promoting effects by targeting PDCD6 in cervical carcinoma cells

OBJECTIVE

MicroRNAs (miRNAs/miRs) have been reported to participate in progression of multiple tumors including cervical cancer. High-risk human papillomavirus (HPV) type 16 (HPV16) is the most common and lethal HPV type, leading to exceeding 50% of cervical cancer cases. However, the relationship between miRNA and HPV-induced cervical carcinogenesis remains elusive.

RESULTS

Here, HPV16 E6 positively regulated miR-20a expression. Overexpression of miR-20a showed growth-promoting effects on C33A cells (HPV16-negative), and knockdown of miR-20a showed growth-inhibitory effects on CaSki cells (HPV16-positive). In addition, PDCD6 was identified as a target gene of miR-20a. Overexpression of PDCD6 exerted growth-inhibitory effects (opposite to miR-20a overexpression), which could be reversed by miR-20a overexpression. More importantly, activation of AKT and p38 was observed in C33A cells overexpressing miR-20a, and the growth-promoting action of miR-20a could be abated by p38 inhibition.

CONCLUSION

Up-regulation of miR-20a by HPV16 E6 exerted growth-promoting effects by targeting PDCD6 in cervical carcinoma cells. This study demonstrated miR-20a might be a potential therapeutic target in HPV16 E6 infection type of cervical cancer.

Methylation of the HOXA10 Promoter Directs miR-196b-5p-Dependent Cell Proliferation and Invasion of Gastric Cancer Cells

The cross-talk between epigenetics and miRNA expression plays an important role in human tumorigenesis. Herein, the regulation and role of miR-196b-5p in gastric cancer was investigated. qRT-PCR demonstrated that miR-196b-5p is significantly overexpressed in human gastric cancer tissues (P < 0.01). In addition, it was determined that HOXA10, a homeobox family member and host gene for miR-196b-5p, is overexpressed and positively correlated with miR-196b-5p expression levels (P < 0.001). Quantitative pyrosequencing methylation analysis demonstrated significantly lower levels of DNA methylation at the HOXA10 promoter in gastric cancer, as compared with nonneoplastic gastric mucosa specimens. 5-Aza-2'-deoxycytidine treatment confirmed that demethylation of HOXA10 promoter induces the expression of HOXA10 and miR-196b-5p in gastric cancer cell model systems. Using the Tff1 knockout mouse model of gastric neoplasia, hypomethylation and overexpression of HOXA10 and miR-196b-5p in gastric tumors was observed, as compared with normal gastric mucosa from Tff1 wild-type mice. Mechanistically, reconstitution of TFF1 in human gastric cancer cells led to an increased HOXA10 promoter methylation with reduced expression of HOXA10 and miR-196b-5p. Functionally, miR-196b-5p reconstitution promoted human gastric cancer cell proliferation and invasion in vitro In summary, the current data demonstrate overexpression of miR-196b-5p in gastric cancer and suggest that TFF1 plays an important role in suppressing the expression of miR-196b-5p by mediating DNA methylation of the HOXA10 promoter. Loss of TFF1 expression may promote proliferation and invasion of gastric cancer cells through induction of promoter hypomethylation and expression of the HOXA10/miR-196b-5p axis.Implications: This study indicates that loss of TFF1 promotes the aberrant overexpression of HOXA10 and miR-196b-5p by demethylation of the HOXA10 promoter, which provides a new perspective of TFF1/HOXA10/miR-196b-5p functions in human gastric cancer. Mol Cancer Res; 16(4); 696-706. ©2018 AACR.

LncRNA NEAT1 enhances the radio-resistance of cervical cancer via miR-193b-3p/CCND1 axis

LncRNAs have become a hot topic in various cancer-related researches. Radio-resistance is a great threat for cancer therapy. However, how lncRNAs affect the radio-resistance in cervical cancer is masked. As for our paper, it was discovered that NEAT1 was highly expressed in cervical cancer tissues and non-sensitive tissues as well as radio-resistant cell lines. And the overexpression of NEAT1 accelerated proliferation, while the knockdown of NEAT1 had the opposite result. The effect of NEAT1 on cell proliferation was dependent on the dose of ionizing radiation. And the silence of NEAT1 also caused cell cycle arrest in G0/G1 phase, and triggered more apoptosis, indicating the oncogenic role of NEAT1 in cervical cancer. Next, mechanistic assays affirmed that NEAT1 could function as a ceRNA to regulate cyclin D1 through sponging miR-193b-3p in cervical cancer. Rescue assays were employed to validate that miR-193b-3p and cyclin D1 could inhibit NEAT1-mediated suppressive effect on proliferation, and its stimulative effect on cell cycle arrest and apoptosis. In general, this article disclosed that NEAT1 could facilitate the radio-resistance of cervical cancer via competitively binding miR-193b-3p to up-regulate the expression of cyclin D1.

MiR-193b regulates breast cancer cell migration and vasculogenic mimicry by targeting dimethylarginine dimethylaminohydrolase 1

Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is responsible for metabolism of an endogenous inhibitor of nitric oxide synthase (NOS), asymmetric dimethylarginine (ADMA), which plays a key role in modulating angiogenesis. In addition to angiogenesis, tumours can establish a vascular network by forming vessel-like structures from tumour cells; a process termed vasculogenic mimicry (VM). Here, we identified over-expression of DDAH1 in aggressive MDA-MB-231, MDA-MB-453 and BT549 breast cancer cell lines when compared to normal mammary epithelial cells. DDAH1 expression was inversely correlated with the microRNA miR-193b. In DDAH1⁺ MDA-MB-231 cells, ectopic expression of miR-193b reduced DDAH1 expression and the conversion of ADMA to citrulline. In DDAH1⁻ MCF7 cells, inhibition of miR-193b elevated DDAH1 expression. Luciferase reporter assays demonstrated DDAH1 as a direct target of miR-193b. MDA-MB-231 cells organised into tube structures in an in vitro assay of VM, which was significantly inhibited by DDAH1 knockdown or miR-193b expression. Mechanistically, we found miR-193b regulates cell proliferation and migration of MDA-MB-231 cells, whilst DDAH1 knockdown inhibited cell migration. These studies represent the first evidence for DDAH1 expression, regulation and function in breast cancer cells, and highlights that targeting DDAH1 expression and/or enzymatic activity may be a valid option in the treatment of aggressive breast cancers.

The association between polymorphisms in microRNA genes and cervical cancer in a Chinese Han population

Several studies have confirmed the crucial roles of microRNAs (miRNAs) in cancer occurrence. In addition, single nucleotide polymorphisms (SNPs) in miRNA genes have been associated with various cancers. The aim of the present study was to investigate the association of SNPs in miRNA genes with cervical intraepithelial neoplasia (CIN) and cervical cancer in a Chinese Han population. We searched SNPs in nineteen miRNAs by sequencing healthy individuals (n=50). Then, a total of 400 patients with CIN, 609 patients with cervical cancer and 583 healthy individuals were recruited to genotype the SNPs using a Taqman assay. The results showed that only five of the nineteen miRNAs had SNPs (rs11134527 in pri-miR-218-2; rs74693964 in pri-miR-145; rs6062251 in pri-miR-133a2; rs531564 in pri-miR-124-1; and rs1834306 in pri-miR-100) in this Chinese Han population. The frequency of the rs11134527A allele was significantly higher in the control group than in CIN and cervical cancer groups (P=0.011 and 0.035, respectively). The frequency of the rs531564G allele was higher in the CIN and control groups than in the cervical cancer group (P=0.019 and 0.017, respectively). These results indicated that rs11134527 in pri-miR-218-2 and rs531564 in pri-miR-124-1 could be associated with CIN and cervical cancer in the Chinese Han population.

ErbB2 signaling epigenetically suppresses microRNA-205 transcription via Ras/Raf/MEK/ERK pathway in breast cancer

We previously reported that microRNA-205 (miR-205) is downregulated by overexpression of the receptor tyrosine kinase ErbB2 and that ectopic transfection of miR-205 precursor decreases ErbB2 tumorigenicity in soft agar. In this study, we further analyzed the regulatory mechanisms linking ErbB2 overexpression and miR-205 downregulation. In ErbB2-overexpressing breast epithelial cells, miR-205 expression was significantly increased by treatment with MEK inhibitor U0126 or PD98059, Raf-1 inhibitor ZM-336372, and ERK inhibitor SCH772984, but PI3K inhibitor LY294002 and p38 MAPK inhibitor SB203580 had no effect. We established breast epithelial cells overexpressing RafCAAX, a constitutively active form of Raf-1, and showed that overexpression of RafCAAX dramatically reduced miR-205 expression. In RafCAAX-overexpressing cells, miR-205 expression was also significantly increased by SCH772984. Moreover, miR-205 expression was significantly increased by treatment with DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine and expression of several DNMT family members was increased in both ErbB2- and RafCAAX-overexpressing cells. DNA methylation analysis by bisulfite sequencing revealed that the putative miR-205 promoters were predominantly hypermethylated in both ErbB2- and RafCAAX-overexpressing cells. Reporter activity of the putative miR-205 promoters was reduced in both ErbB2-overexpressing and RafCAAX-overexpressing cells. Together, these findings indicate that ErbB2 signaling epigenetically suppresses miR-205 transcription via the Ras/Raf/MEK/ERK pathway.

Molecular approaches for HPV genotyping and HPV-DNA physical status

Persistent infection with high-risk human papillomavirus (HPV) genotypes is the leading cause of cervical cancer development. To this end several studies have focused on designing molecular assays for HPV genotyping, which are considered as the gold standard for the early diagnosis of HPV infection. Moreover, the tendency of HPV DNA to be integrated into the host chromosome is a determining event for cervical oncogenesis. Thus, the establishment of molecular techniques was promoted in order to investigate the physical status of the HPV DNA and the locus of viral insertion into the host chromosome. The molecular approaches that have been developed recently facilitate the collection of a wide spectrum of valuable information specific to each individual patient and therefore can significantly contribute to the establishment of a personalised prognosis, diagnosis and treatment of HPV-positive patients. The present review focuses on state of the art molecular assays for HPV detection and genotyping for intra-lesion analyses, it examines molecular approaches for the determination of HPV-DNA physical status and it discusses the criteria for selecting the most appropriate regions of viral DNA to be incorporated in HPV genotyping and in the determination of HPV-DNA physical status.

Regulatory mechanisms of microRNA expression

MicroRNAs (miRs, miRNAs) are small molecules of 18-22 nucleotides that serve as important regulators of gene expression at the post-transcriptional level. One of the mechanisms through which miRNAs regulate gene expression involves the interaction of their "seed" sequences primarily with 3'-end and more rarely with 5'-end, of mRNA transcribed from target genes. Numerous studies over the past decade have been devoted to quantitative and qualitative assessment of miRNAs expression and have shown remarkable changes in miRNA expression profiles in various diseases. Thus, profiling of miRNA expression can be an important tool for diagnostics and treatment of disease. However, less attention has been paid towards understanding the underlying reasons for changes in miRNA expression, especially in cancer cells. The purpose of this review is to analyze and systematize current data that explains reasons for changes in the expression of miRNAs. The review will cover both transcriptional (changes in gene expression and promoter hypermethylation) and post-transcriptional (changes in miRNA processing) mechanisms of regulation of miRNA expression, as well as effects of endogenous (hormones, cytokines) and exogenous (xenobiotics) compounds on the miRNA expression. The review will summarize the complex multilevel regulation of miRNA expression, in relation to cell type, physiological state of the body and various external factors.