A higher degree of expression of DNA methyl transferase 1 in cervical cancer is associated with poor survival outcome

Alpha-linolenic acid-mediated epigenetic reprogramming of cervical cancer cell lines

Cervical cancer, the fourth most common cancer globally and the second most prevalent cancer among women in India, is primarily caused by Human Papilloma Virus (HPV). The association of diet with cancer etiology and prevention has been well established and nutrition has been shown to regulate cancer through modulation of epigenetic markers. Dietary fatty acids, especially omega-3, reduce the risk of cancer by preventing or reversing the progression through a variety of cellular targets, including epigenetic regulation. In this work, we have evaluated the potential of ALA (α linolenic acid), an ω-3 fatty acid, to regulate cervical cancer through epigenetic mechanisms. The effect of ALA was evaluated on the regulation of histone deacetylases1, DNA methyltransferases 1, and 3b, and global DNA methylation by ELISA. RT-PCR was utilized to assess the expression of tumor regulatory genes (hTERT, DAPK, RARβ, and CDH1) and their promoter methylation in HeLa (HPV18-positive), SiHa (HPV16-positive) and C33a (HPV-negative) cervical cancer cell lines. ALA increased DNA demethylase, HMTs, and HATs while decreasing global DNA methylation, DNMT, HDMs, and HDACs mRNA expression/activity in all cervical cancer cell lines. ALA downregulated hTERT oncogene while upregulating the mRNA expression of TSGs (Tumor Suppressor Genes) CDH1, RARβ, and DAPK in all the cell lines. ALA reduced methylation in the 5' CpG island of CDH1, RARβ, and DAPK1 promoters and reduced global DNA methylation in cervical cancer cell lines. These results suggest that ALA regulates the growth of cervical cancer cells by targeting epigenetic markers, shedding light on its potential therapeutic role in cervical cancer management.

Kaempferol Targets Global Epigenetic Modifiers to Impedes Growth and Migratory Ability of HeLa Cells

Dietary bioactive agents can curb tumour progression through chromatin alterations. Thus, this study attempts to evaluate the influence of kaempferol on epigenome modification in HeLa cells. Biochemical analysis for global DNA methylation-LINE 1, DNMTs (DNA methyltransferases), HAT (histone acetyl transferase), HDACs (histone deacetylases) and HMTs (histone methyltransferases) were examined with their transcript level expression through qPCR. Also, H3 and H4 histone modification marks were quantitated by an ELISA-based assay. Moreover, qPCR and protein profiler were performed to analyse the expression of migratory genes at both mRNA and protein levels, respectively, that was further substantiated through colony formation, invasion, and scratch wound assays. Finally, DNA methyl-sequencing was performed to analyse the promoter methylation of TSGs (tumour suppressor genes) and corroborated by analysing selected TSGs' expression. Kaempferol treatment did not alter the global DNA methylation-LINE 1 compared to untreated control, however, it reduced the expression and biochemical activities of DNMT and HDAC, which can be linked to their hypermethylation by kaempferol exposure. Concordant with the reduced expression of HMTs, HATs and other epi-enzymes, various histone H3 and H4 marks were also observed to be modulated. Kaempferol exposure led to promoter hypomethylation of various TSGs (such as WIF1, RUNX1, RARβ, SOX1), which subsequently led to enhanced expression at the mRNA level, which corresponds to their reactivation. Molecular studies were consistent with cell-based studies, which demonstrated a strong growth inhibitory and anti-migratory effect of kaempferol. This research helps to understand the probable mechanism used by kaempferol as a potential epigenetic modifier.

Dysregulation of different modes of programmed cell death by epigenetic modifications and their role in cancer

Modifications of epigenetic factors affect our lives and can give important information regarding one's state of health. In cancer, epigenetic modifications play a crucial role, as they influence various programmed cell death types. The purpose of this review is to investigate how epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs, influence various cell death processes in suppressing or promoting cancer development. Autophagy and apoptosis are the most investigated programmed cell death modes, as based on the tumor stage these cell death types can either promote or prevent cancer evolution. Therefore, our discussion focuses on how epigenetic modifications affect autophagy and apoptosis, as well as their diagnostic and therapeutical potential in combination with available chemotherapeutics. Additionally, we summarize the available data regarding the role of epigenetic modifications on other programmed cell death modes, such as ferroptosis, necroptosis, and parthanatos in cancer and discuss current advancements.

Casticin Attenuates Stemness in Cervical Cancer Stem-Like Cells by Regulating Activity and Expression of DNMT1

OBJECTIVE

To explore whether casticin (CAS) suppresses stemness in cancer stem-like cells (CSLCs) obtained from human cervical cancer (CCSLCs) and the underlying mechanism.

METHODS

Spheres from HeLa and CaSki cells were used as CCSLCs. DNA methyltransferase 1 (DNMT1) activity and mRNA levels, self-renewal capability (Nanog and Sox2), and cancer stem cell markers (CD133 and CD44), were detected by a colorimetric DNMT activity/inhibition assay kit, quantitative real-time reverse transcription-polymerase chain reaction, sphere and colony formation assays, and immunoblot, respectively. Knockdown and overexpression of DNMT1 by transfection with shRNA and cDNA, respectively, were performed to explore the mechanism for action of CAS (0, 10, 30, and 100 nmol/L).

RESULTS

DNMT1 activity was increased in CCSLCs compared with HeLa and CaSki cells (P<0.05). In addition, HeLa-derived CCSLCs transfected with DNMT1 shRNA showed reduced sphere and colony formation abilities, and lower CD133, CD44, Nanog and Sox2 protein expressions (P<0.05). Conversely, overexpression of DNMT1 in HeLa cells exhibited the oppositive effects. Furthermore, CAS significantly reduced DNMT1 activity and transcription levels as well as stemness in HeLa-derived CCSLCs (P<0.05). Interestingly, DNMT1 knockdown enhanced the inhibitory effect of CAS on stemness. As expected, DNMT1 overexpression reversed the inhibitory effect of CAS on stemness in HeLa cells.

CONCLUSION

CAS effectively inhibits stemness in CCSLCs through suppression of DNMT1 activation, suggesting that CAS acts as a promising preventive and therapeutic candidate in cervical cancer.

Inhibition of SUMOylation enhances DNA hypomethylating drug efficacy to reduce outgrowth of hematopoietic malignancies

Combination therapies targeting malignancies aim to increase treatment efficacy and reduce toxicity. Hypomethylating drug 5-Aza-2'-deoxycytidine (5-Aza-2') enhances transcription of tumor suppressor genes and induces replication errors via entrapment of DNMT1, yielding DNA-protein crosslinks. Post-translational modification by SUMO plays major roles in the DNA damage response and is required for degradation of entrapped DNMT1. Here, we combine SUMOylation inhibitor TAK981 and DNA-hypomethylating agent 5-Aza-2'-deoxycytidine to improve treatment of MYC driven hematopoietic malignancies, since MYC overexpressing tumors are sensitive to SUMOylation inhibition. We studied the classical MYC driven malignancy Burkitt lymphoma, as well as diffuse large B-cell lymphoma (DLBCL) with and without MYC translocation. SUMO inhibition prolonged the entrapment of DNMT1 to DNA, resulting in DNA damage. An increase in DNA damage was observed in cells co-treated with TAK981 and 5-Aza-2'. Both drugs synergized to reduce cell proliferation in vitro in a B cell lymphoma cell panel, including Burkitt lymphoma and DLBCL. In vivo experiments combining TAK981 (25 mg/kg) and 5-Aza-2' (2.5 mg/kg) showed a significant reduction in outgrowth of Burkitt lymphoma in an orthotopic xenograft model. Our results demonstrate the potential of tailored combination of drugs, based on insight in molecular mechanisms, to improve the efficacy of cancer therapies.

High nuclear expression of DNMT1 in correlation with inactivation of TET1 portray worst prognosis among the cervical carcinoma patients: clinical implications

In this study, we aimed to understand the interplay of the epigenetic modifier genes DNMT1 and TET1 along with HPV infection in the cervical epithelium and how it changes during tumorigenesis. For this purpose, initially the bioinformatical analysis (methylation and expression profile) of DNMT1 and TET1 was analyzed in the TCGA dataset. Next genetic (deletion) and epigenetic profiling (promoter methylation) of DNMT1 and TET1 were done in our sample pool and also validated in CACX cell lines as well. The results were further correlated with different clinicopathological parameters. Our data revealed that HPV infection in basal/parabasal layers of cervical epithelium actually disrupts the epigenetic homeostasis of DNMT1 and TET1 proteins which ultimately leads to the high expression of DNMT1 along with further reduction in TET1 protein during the development of carcinoma. Further, in-depth look into the results revealed that comparatively low methylation frequency of DNMT1 coupled with high promoter methylation and deletion frequency [22-46%] of TET1 were the plausible reasons of their antagonistic expression profile during the progression of the disease. Interestingly, the prevalence of DNMT1 [9.1%] and TET1 promoter methylation [22.7%] found in both the plasma DNA of the respective CACX patients implicated its diagnostic importance in this study. Lastly, molecular alteration of TET1 alone or in combination with DNMT1 showed the worst overall survival among the patients. Hence, it may be concluded that an inverse molecular profile of DNMT1 and TET1 genes seen in the proliferative basal-parabasal layers of the cervical epithelium was aggravated during the development of CACX along with genetic and epigenetic changes due to HPV infection.

Aberrations of DNA methylation in cancer

DNA methylation is a chromatin modification that plays an important role in the epigenetic regulation of gene expression. Changes in DNA methylation patterns are characteristic of many malignant neoplasms. DNA methylation is occurred by DNA methyltransferases (DNMTs), while demethylation is mediated by TET family proteins. Mutations and changes in the expression profile of these enzymes lead to DNA hypo- and hypermethylation and have a strong impact on carcinogenesis. In this review, we considered the key aspects of the mechanisms of regulation of DNA methylation and demethylation, and also analyzed the role of DNA methyltransferases and TET family proteins in the pathogenesis of various malignant neoplasms.During the preparation of the review, we used the following biomedical literature information bases: Scopus (504), PubMed (553), Web of Science (1568), eLibrary (190). To obtain full-text documents, the electronic resources of PubMed Central (PMC), Science Direct, Research Gate, CyberLeninka were used. To analyze the mutational profile of epigenetic regulatory enzymes, we used the cBioportal portal (https://www.cbioportal.org / ), data from The AACR Project GENIE Consortium (https://www.mycancergenome.org / ), COSMIC, Clinvar, and The Cancer Genome Atlas (TCGA).

Chrysin Modulates Aberrant Epigenetic Variations and Hampers Migratory Behavior of Human Cervical (HeLa) Cells

Purpose: Plant-derived phytochemicals have shown epigenetic modulatory effect in different types of cancer by reversing the pattern of DNA methylation and chromatin modulation, thereby restoring the function of silenced tumor-suppressor genes. In the present study, attempts have been made to explore chrysin-mediated epigenetic alterations in HeLa cells. Methods: Colony formation and migration assays followed by methylation-specific PCR for examining the methylation status of CpG promoters of various tumor-suppressor genes (TSGs) and the expression of these TSGs at the transcript and protein levels were performed. Furthermore, global DNA methylation; biochemical activities of DNA methyltransferases (DNMTs), histone methyl transferases (HMTs), histone deacetylases (HDACs), and histone acetyl transferases (HATs) along with the expression analysis of chromatin-modifying enzymes; and H3 and H4 histone modification marks analyses were performed after chrysin treatment. Results: The experimental analyses revealed that chrysin treatment encourages cytostatic behavior as well as inhibits the migration capacity of HeLa cells in a time- and dose-dependent manner. Chrysin reduces the methylation of various tumor-suppressor genes, leading to their reactivation at mRNA and protein levels. The expression levels of various chromatin-modifying enzymes viz DNMTs, HMTs, HDACs, and HATS were found to be decreased, and H3 and H4 histone modification marks were modulated too. Also, reduced global DNA methylation was observed following the treatment of chrysin. Conclusion: This study concludes that chrysin can be used as a potential epigenetic modifier for cancer treatment and warrants for further experimental validation.

Antineoplastic action of sulforaphane on HeLa cells by modulation of signaling pathways and epigenetic pathways

BACKGROUND

Epigenetic modifications alter signaling and molecular pathways; moreover, they are an important therapeutic target. This study examined the effect of sulforaphane on molecular targets in HeLa cells.

METHODS

Quantitative PCR of various molecular targets was performed. Activity of epigenetic enzymes was measured by ELISA and molecular docking analysis was conducted. Promoter methylation of some tumor suppressor genes was quantified using PCR based methylation array. In-silico protein-protein interaction network analysis was performed to understand the effect of transcriptional changes.

RESULTS

Quantitative PCR demonstrated the transcriptional modulation of genes involved in proliferation, metastasis, inflammation, signal transduction pathways and chromatin modifiers. Sulforaphane reduced the enzymatic activity of DNA methyl transferases, histone deacetylases and histone methyltransferases. Molecular docking results suggest that sulforaphane competitively inhibited several DNA methyl transferases and histone deacetylases. Promoter 5'CpG methylation levels of selected tumor suppressor genes was found to be reduced which correlated with their transcriptional increase as well modulation of epigenetic enzymes. Further, protein-protein interaction network analysis discerned the participation of genes towards cancer pathways. Functional enrichment and pathway-based analysis represented the modulation of epigenetic and signaling pathways on sulforaphane treatment.

CONCLUSIONS

The modulation in transcriptional status of epigenetic regulators, genes involved in tumorigenesis resulting in tumor suppressor genes demethylation and re-expression underscores the mechanism behind the anticancer effect of sulforaphane on HeLa cells.

Interplay between DNA Methyltransferase 1 and microRNAs During Tumorigenesis

Cancer is a genetic disease resulting from genomic changes; however, epigenetic alterations act synergistically with these changes during tumorigenesis and cancer progression. Epigenetic variations are gaining more attention as an important regulator in tumor progression, metastasis and therapy resistance. Aberrant DNA methylation at CpG islands is a central event in epigeneticmediated gene silencing of various tumor suppressor genes. DNA methyltransferase 1 (DNMT1) predominately methylates at CpG islands on hemimethylated DNA substrates in proliferation of cells. DNMT1 has been shown to be overexpressed in various cancer types and exhibits tumor-promoting potential. The major drawbacks to DNMT1-targeted cancer therapy are the adverse effects arising from nucleoside and non-nucleoside based DNMT1 inhibitors. This paper focuses on the regulation of DNMT1 by various microRNAs (miRNAs), which may be assigned as future DNMT1 modulators, and highlights how DNMT1 regulates various miRNAs involved in tumor suppression. Importantly, the role of reciprocal inhibition between DNMT1 and certain miRNAs in tumorigenic potential is approached in this review. Hence, this review seeks to project an efficient and strategic approach using certain miRNAs in conjunction with conventional DNMT1 inhibitors as a novel cancer therapy. It has also been pinpointed to select miRNA candidates associated with DNMT1 regulation that may not only serve as potential biomarkers for cancer diagnosis and prognosis, but may also predict the existence of aberrant methylation activity in cancer cells.

Glyphosate and AMPA Induce Alterations in Expression of Genes Involved in Chromatin Architecture in Human Peripheral Blood Mononuclear Cells (In Vitro)

We have determined the effect of glyphosate and aminomethylphosphonic acid (AMPA) on expression of genes involved in chromatin architecture in human peripheral blood mononuclear cells (PBMCs). The cells were incubated with glyphosate and AMPA in the concentrations ranging from 0.5 to 100 μM and from 0.5, to 250 μM, respectively. The expression profile of the following genes by quantitative Real-Time PCR was evaluated: Genes involved in the DNA methylation (DNMT1, DNMT3A) and DNA demethylation process (TET3) and those involved in chromatin remodeling: genes involved in the modification of histone methylation (EHMT1, EHMT2) and genes involved in the modification of histone deacetylation (HDAC3, HDAC5). Gene profiling showed that glyphosate changed the expression of DNMT1, DMNT3A, and HDAC3, while AMPA changed the expression of DNMT1 and HDAC3. The results also revealed that glyphosate at lower concentrations than AMPA upregulated the expression of the tested genes. Both compounds studied altered expression of genes, which are characteristic for the regulation of transcriptionally inactive chromatin. However, the unknown activity of many other proteins involved in chromatin structure regulation prevents to carry out an unambiguous evaluation of the effect of tested xenobiotics on the studied process. Undoubtedly, we have observed that glyphosate and AMPA affect epigenetic processes that regulate chromatin architecture.

MicroRNA-29a inhibits cell proliferation and arrests cell cycle by modulating p16 methylation in cervical cancer

Cervical cancer is the second most common gynecological malignancy. Accumulating evidence has suggested that microRNAs (miRNAs) are involved in the occurrence and development of cervical cancer. The present study aimed to investigate the function and underlying molecular mechanism of microRNA (miRNA/miR)-29a in cervical cancer. Reverse transcription-quantitative PCR and methylation-specific PCR were used to examine the expression of miR-29a and methylated status of p16 promoter, respectively. Cell Counting Kit-8 analysis and flow cytometry were performed to evaluate cell viability and cycle, respectively. Dual-luciferase reporter assay was performed to verify the interaction between miR-29a and its targets. Western blot analysis was performed to detect the protein levels of DNA methyltransferases (DNMT)3A and DNMT3B. The results demonstrated that miR-29a expression was downregulated in cervical cancer tissues and cells, and negatively correlated with p16 promoter hypermethylation. Furthermore, cell experiments confirmed that miR-29a suppressed cell proliferation and induced cell cycle arrest in HeLa and C-33A cells. Mechanically, miR-29a restored normal methylation pattern of the p16 gene by sponging DNMT3A and DNMT3B. Taken together, the results of the present study demonstrated the epigenetic regulation of tumor suppressor p16 by miR-29a as a unique mechanism, thus providing a rationale for the development of miRNA-based strategies in the treatment of cervical cancer.

Dietary isothiocyanates inhibit cancer progression by modulation of epigenome

Cell cycle, growth, survival and metabolism are tightly regulated together and failure in cellular regulation leads to carcinogenesis. Several signaling pathways like the PI3K, WNT, MAPK and NFKb pathway exhibit aberrations in cancer and help achieve hallmark capabilities. Clinical research and in vitro studies have highlighted the role of epigenetic alterations in cancer onset and development. Altered gene expression patterns enabled by changes in DNA methylation, histone modifications and RNA processing have proven roles in cancer hallmark acquisition. The reversible nature of epigenetic processes offers robust therapeutic targets. Dietary bioactive compounds offer a vast compendium of effective therapeutic moieties. Isothiocyanates (ITCs) sourced from cruciferous vegetables demonstrate anti-proliferative, pro-apoptotic, anti-inflammatory, anti-migratory and anti-angiogenic effect against several cancers. ITCs also modulate the redox environment, modulate signaling pathways including PI3K, MAPK, WNT, and NFkB. They also modulate the epigenetic machinery by regulating the expression and activity of DNA methyltransferases, histone modifiers and miRNA. This further enhances their transcriptional modulation of key cellular regulators. In this review, we comprehensively assess the impact of ITCs such as sulforaphane, phenethyl isothiocyanate, benzyl isothiocyanate and allyl isothiocyanate on cancer and document their effect on various molecular targets. Overall, this will facilitate consolidation of the current understanding of the anti-cancer and epigenetic modulatory potential of these compounds and recognize the gaps in literature. Further, we discuss avenues of future research to develop these compounds as potential therapeutic entities.

Methylomic Signatures of High Grade Serous Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) harbours aberrant epigenetic features, including DNA methylation. In this study we delineate pathways and networks altered by DNA methylation and associated with HGSOC initiation and progression to a platinum-resistant state. By including tumours from patients who had been treated with the hypomethylating agent (HMA) guadecitabine, we also addressed the role of HMAs in treatment of HGSOC. Tumours from patients with primary (platinum-naïve) HGSOC (n = 20) were compared to patients with recurrent platinum-resistant HGSOC and enrolled in a recently completed clinical trial (NCT01696032). Human ovarian surface epithelial cells (HOSE; n = 5 samples) served as normal controls. Genome-wide methylation profiles were determined. DNA methyltransferase (DNMT) expression levels were examined by immunohistochemistry and correlated with clinical outcomes. Cancer-related and tumorigenesis networks were enriched among differentially methylated genes (DMGs) in primary OC vs. HOSE. When comparing platinum-resistant and primary tumours, 452 CpG island (CGI)-containing gene promoters acquired DNA methylation; of those loci, decreased (P < 0.01) methylation after HMA treatment was observed in 42% (n = 189 CGI). Stem cell pluripotency and cytokine networks were enriched in recurrent platinum-resistant OC tumours, while drug metabolism and transport-related networks were downregulated in tumours from HMA-treated patients compared to HOSE. Lower DNMT1 and 3B protein levels in pre-treatment tumours were associated with improved progression-free survival. The findings provide important insight into the DNA methylation landscape of HGSOC tumorigenesis, platinum resistance and epigenetic resensitization. Epigenetic reprogramming plays an important role in HGSOC aetiology and contributes to clinical outcomes.

Epigallocatechin gallate inhibits HeLa cells by modulation of epigenetics and signaling pathways

This study examines the effect of epigallocatechin gallate (EGCG) on signaling pathways, epigenetic modulators and tumour suppressor genes in cervical cancer cells, HeLa. qRT-PCR, ELISA-based enzymatic assays and in silico studies were used to catalogue the modulation of these genes by EGCG treatment. qRT-PCR showed transcriptional modulation of several epigenetic modifiers including DNA methyltransferases and histone modifiers (DNMT1, DNMT3B, DNMT3A, AURKA, AURKC, AURKB, KDM4A, KDM5C, PRMT7, PRMT6, UBE2B, HDAC5, HDAC6, HDAC7 and HDAC11. Furthermore, ELISA-based assays showed that EGCG lowered the activity of DNA methyltransferases, histone deacetylases and histone methyltransferases (H3K9). Molecular docking results suggests that EGCG may competitively inhibit some epigenetic enzymes (DNMT1, DNMT3A, HDAC2, HDAC3, HDAC4, HDAC7 and EZH2). A functional outcome of these epigenetic alterations could be inferred from the reversal of promoter hypermethylation of tumour suppressor genes by quantitative methylation array and transcriptional re-expression of tumour suppressor genes including TP73, PTEN, SOCS1, CDH1, RARβ, and DAPK1 by qRT-PCR. Downregulation of key signaling moieties of PI3K, Wnt and MAPK pathways, cell cycle regulators, metastasis regulators and pro-inflammatory moieties including TERT, CCNB1, CCNB2, MMP2, MMP7. PIK3C2B, PIK3CA, MAPK8 and IL6 was also observed. In silico protein-protein interaction network analysis followed by KEGG analysis discerned the active participation of gene sets towards cancer pathways. This study comprehensively explains EGCG's anti-cancer mechanism via the synchronized transcriptional alteration of several molecular targets across different signaling pathways and reversal of tumour suppressor gene silencing through modulation of epigenetic enzymes.

Regulation of DNA methylation machinery by epi-miRNAs in human cancer: emerging new targets in cancer therapy

Disruption in DNA methylation processes can lead to alteration in gene expression and function that would ultimately result in malignant transformation. In this way, studies have shown that, in cancers, methylation-associated silencing inactivates tumor suppressor genes, as effectively as mutations. DNA methylation machinery is composed of several genes, including those with DNA methyltransferases activity, proteins that bind to methylated cytosine in the promoter region, and enzymes with demethylase activity. Based on a prominent body of evidence, DNA methylation machinery could be regulated by microRNAs (miRNAs) called epi-miRNAs. Numerous studies demonstrated that dysregulation in DNA methylation regulators like upstream epi-miRNAs is indispensable for carcinogenesis; consequently, the malignant capacity of these cells could be reversed by restoring of this regulatory system in cancer. Conceivably, recognition of these epi-miRNAs in cancer cells could not only reveal novel molecular entities in carcinogenesis, but also render promising targets for cancer therapy. In this review, at first, we have an overview of the methylation alteration in cancers, and the effect of this phenomenon in miRNAs expression and after that, we conduct an in-depth discussion about the regulation of DNA methylation regulators by epi-miRNAs in cancer cells.

The impact of EBV on the epigenetics of gastric carcinoma

EBV is an important human tumor virus and is closely related to the occurrence of a variety of tumors, involving 10% of gastric cancer. In EBV-associated gastric carcinoma (EBVaGC), EBV expresses restrict viral genes including EBV nuclear antigen 1, EBV encoded small RNAs, Bam HI-A rightward transcripts, latent membrane protein 2A and miRNAs. The role of EBV in gastric carcinogenesis has received increasing attention and is considered to be another pathogenic factor in addition to Helicobacter pylori. A typical characteristic of EBVaGC is the extensive methylation of viral and host genome. Combined with other epigenetic mechanisms, EBV infection acts as an epigenetic driver of EBVaGC oncogenesis. In this review we discuss recent findings of EBV effect on host epigenetic alterations in EBVaGC and its role in oncogenic process.

Targeting epigenetic regulators for cancer therapy: mechanisms and advances in clinical trials

Epigenetic alternations concern heritable yet reversible changes in histone or DNA modifications that regulate gene activity beyond the underlying sequence. Epigenetic dysregulation is often linked to human disease, notably cancer. With the development of various drugs targeting epigenetic regulators, epigenetic-targeted therapy has been applied in the treatment of hematological malignancies and has exhibited viable therapeutic potential for solid tumors in preclinical and clinical trials. In this review, we summarize the aberrant functions of enzymes in DNA methylation, histone acetylation and histone methylation during tumor progression and highlight the development of inhibitors of or drugs targeted at epigenetic enzymes.

DNMT1 recruited by EZH2-mediated silencing of miR-484 contributes to the malignancy of cervical cancer cells through MMP14 and HNF1A

BACKGROUND

Emerging evidence indicates that dysregulation of microRNAs (miRNAs) contributes to cervical cancer (CC) tumorigenesis and development. Previous work showed that miR-484 which regulated the EMT process was obviously downregulated in CC. However, little is known about the precise mechanism.

RESULTS

We found that the deficiency of EZH2-recruited DNA methyltransferases DNMT1 reduced the CpG methylation of miR-484 promoter and then increased the miR-484 expression. Furthermore, the cell membrane-bound matrix metalloproteinase (MMP14) and the hepatocyte nuclear factor 1A (HNF1A) were found to be downregulated by miR-484. miR-484 repressed the expression of MMP14 and HNF1A inhibiting CC growth and metastasis in vitro and in vivo. Upregulation of MMP14 and HNF1A promotes the CC cell adhesion and EMT, all of which contribute to cell motility and metastasis. Moreover, miR-484 negatively regulates the WNT/MAPK and TNF signaling pathway by downregulating HNF1A and MMP14 respectively. Thus, miR-484, who is downregulated by DNMT1-mediated hypermethylation in its promoter, functions as a tumor suppressor by inhibiting MMP14 and HNF1A expression in CC.

CONCLUSION

Our finding characterizes miR-484 as a key suppressive regulator in CC metastasis and reveals a DNMT1-mediated epigenetic mechanism for miR-484 silencing, expanding our understanding of the molecular mechanism underlying CC progression and metastasis.

Genistein Modulates Signaling Pathways and Targets Several Epigenetic Markers in HeLa Cells

BACKGROUND

Several epigenetic changes are responsible for transcriptional alterations of signaling pathways and tumour suppressor genes (TSGs) contributing to carcinogenesis. This study was aimed to examine the effect of the phytochemical, genistein on various molecular targets in HeLa cells.

METHODS

Quantitative PCR was used to analyze the expression of various molecular targets. Biochemical assays were employed to study the epigenetic enzymes. To correlate the transcriptional status of the selected TSGs and epigenetic modulation, their promoter 5'CpG methylation levels were evaluated by quantitative methylation array followed by methylation specific restriction digestion.

RESULTS

The expression of several genes involved in the cell cycle regulation, migration, inflammation, phosphatidylinositol 3-kinase (PI3K) and mitogen activated kinase-like protein (MAPK) pathway were found to be modulated including CCNB1, TWIST1, MMP14, TERT, AKT1, PTPRR, FOS and IL1A. Genistein modulated the expression of DNA methyltransferases (DNMTs), histone deacetylases (HDACs), histone methyltransferases (HMTs), demethylases, and histone phosphorylases. Furthermore, genistein decreased the activity of DNMTs, HDACs, and HMTs and reduced global DNA methylation levels. Promoter methylation of several TSGs, including FHIT, RUNX3, CDH1, PTEN, and SOC51, was lowered with corresponding transcriptional increase. Network analysis indicated similar effect of genistein.

CONCLUSION

This study presents a comprehensive mechanism of action of genistein showcasing effective epigenetic modulation and widespread transcriptional changes resulting in restoration of tumour suppressor gene expression. This study corroborates the development of genistein as a candidate for anti-cancer therapy.

Conversion to resectability using transcatheter arterial chemoembolization alternating with mFOLFOX6 in patients with colorectal liver metastases

Background:

Colorectal cancer is one of the most common malignancies in the world, and about 25% of colorectal cancer patients present with colorectal cancer liver metastases (CRCLM) even at new diagnosis. The study was to evaluate the safety and efficacy of transcatheter arterial chemoembolization (TACE) alternating with mFOLFOX6 in Chinese patients with unresectable CRCLM.

Materials and Methods:

In this study, by combining the systemic and regional treatment, the resectability rate, overall survival, and progression-free survival were measured with addition of TACE. Included patients had Eastern Cooperative Oncology Group performance status 0–2. Sixty-two patients received mFOLFOX6 plus one TACE after 2 weeks of chemotherapy; after 2 weeks, the next periodical treatment repeated. Patients received operation when the liver metastases were converted to resectability or severe tumor-associated complications occurred.

Results:

We found that 28 patients (45.2%) patients received operation after the treatment of TACE combined with systemic chemotherapy. The median time from initial treatment to the operation was 6 months. The median follow-up period was 41 months in all the patients. The 3-year survival rate of resected patients and unresected patients was 54% and 17%, respectively. Post-TACE syndrome was the major adverse reaction (81%). Other adverse reactions were neutropenia, nausea, and neurotoxicity. No patient died of the adverse reactions. The resection rate was related to hepatic segments and vasculature involvement.

Conclusion:

Taken together, TACE alternating with mFOLFOX6 has been proved to be safe and effective for CRCLM treatment to improve resection rate and prolong the survival time.

Epigenetic Dysregulation at the Crossroad of Women's Cancer

An increasingly number of women of all age groups are affected by cancer, despite substantial progress in our understanding of cancer pathobiology, the underlying genomic alterations and signaling cascades, and cellular-environmental interactions. Though our understanding of women’s cancer is far more complete than ever before, there is no comprehensive model to explain the reasons behind the increased incidents of certain reproductive cancer among older as well as younger women. It is generally suspected that environmental and life-style factors affecting hormonal and growth control pathways might help account for the rise of women’s cancers in younger age, as well, via epigenetic mechanisms. Epigenetic regulators play an important role in orchestrating an orderly coordination of cellular signals in gene activity in response to upstream signaling and/or epigenetic modifiers present in a dynamic extracellular milieu. Here we will discuss the broad principles of epigenetic regulation of DNA methylation and demethylation, histone acetylation and deacetylation, and RNA methylation in women’s cancers in the context of gene expression, hormonal action, and the EGFR family of cell surface receptor tyrosine kinases. We anticipate that a better understanding of the epigenetics of women’s cancers may provide new regulatory leads and further fuel the development of new epigenetic biomarkers and therapeutic approaches.

Quercetin modifies 5'CpG promoter methylation and reactivates various tumor suppressor genes by modulating epigenetic marks in human cervical cancer cells

The central role of epigenomic alterations in carcinogenesis has been widely acknowledged, particularly the impact of DNA methylation on gene expression across all stages of carcinogenesis is considered vital for both diagnostic and therapeutic strategies. Dietary phytochemicals hold great promise as safe anticancer agents and effective epigenetic modulators. This study was designed to investigate the potential of a phytochemical, quercetin as a modulator of the epigenetic pathways for anticancer strategies. Biochemical activity of DNA methyltransferases (DNMTs), histone deacetylases (HDACs), histone methyltransferases (HMTs), and global genomic DNA methylation was quantitated by an enzyme-linked immunosorbent assay based assay in quercetin-treated HeLa cells. Molecular docking studies were performed to predict the interaction of quercetin with DNMTs and HDACs. Quantitative methylation array was used to assess quercetin-mediated alterations in the promoter methylation of selected tumor suppressor genes (TSGs). Quercetin induced modulation of chromatin modifiers including DNMTs, HDACs, histone acetyltransferases (HAT) and HMTs, and TSGs were assessed by quantitative reverse transcription PCR (qRT-PCR). It was found that quercetin modulates the expression of various chromatin modifiers and decreases the activity of DNMTs, HDACs, and HMTs in a dose-dependent manner. Molecular docking results suggest that quercetin could function as a competitive inhibitor by interacting with residues in the catalytic cavity of several DNMTs and HDACs. Quercetin downregulated global DNA methylation levels in a dose- and time-dependent manner. The tested TSGs showed steep dose-dependent decline in promoter methylation with the restoration of their expression. Our study provides an understanding of the quercetin's mechanism of action and will aid in its development as a candidate for epigenetic-based anticancer therapy.

The expressions of DNA methyltransferase 1 (DNMT1) and cyclin A1 (CCNA1) in cervical carcinogenesis

OBJECTIVES

The purpose of the present study was to investigate the expressions of DNA methyltransferase 1 (DNMT1) and cyclin A1 (CCNA1) protein and mRNA in the process of cervical carcinogenesis.

METHODS

The specimens were separated into the following groups: control (n=30), low-grade squamous intraepithelial lesions (LSIL, n=30), high-grade squamous intraepithelial lesions (HSIL) and squamous cell cervical cancers (SCC, n=30). Immunohistochemical examination, Western blot and real-time quantitative PCR were used to investigate the protein and mRNA expressions of DNMT1 and CCNA1 in cervical tissues.

RESULTS

We found that the positive expression rate and intensity of DNMT1 mRNA and protein gradually increased in the process of cervical carcinogenesis. However, the increase of the positive expression rate of DNMT1 mRNA and protein form the LSIL group to HSIL group was not significant (P>0.05). After cervical intraepithelial neoplasia (CIN), the positive expression rate and intensity of CCNA1 mRNA and protein significantly decreased with the aggravation of cervical lesions (P<0.05), and there was no significant difference between the LSIL and control groups (P>0.05).

CONCLUSIONS

With the severity of cervical lesions, the expression of DNMT1 protein and mRNA increased gradually. The expression of CCNA1 protein and mRNA decreased gradually. The DNMT1 and CCNA1 expressions are associated with cervical lesions.

DNA methyltransferases in virus-associated cancers

Human tumor viruses are either casually linked or contribute in the development of human cancers. Viruses can stimulate oncogenesis through affecting diverse biological pathways in human cells. Growing data have demonstrated frequent involvement of one of the most characteristic parts of cellular epigenetic machinery, DNA methylation, in the oncogenesis. DNA methylation of cellular genes is catalyzed by DNA methyltransferases (DNMTs) as a key effector enzyme in this process. Dysregulation of DNMTs can cause aberrant gene methylation in promoter of cancer-related genes including tumor suppressor genes, resulting in gene silencing. In this regard, the role of tumor viruses is remarkable. Here, in this review, we used published information to elucidate whether tumor viruses are able to manipulate DNMT regulation, and if so, what are its consequences in the process of oncogenesis. This essay also aims to shed light on which cellular pathways have been engaged by viruses to induce DNMTs.

The role of DNA methylation in ageing and cancer

The aim of the present review paper is to survey the literature related to DNA methylation, and its association with cancer and ageing. The review will outline the key factors, including diet, which modulate DNA methylation. Our rationale for conducting this review is that ageing and diseases, including cancer, are often accompanied by aberrant DNA methylation, a key epigenetic process, which is crucial to the regulation of gene expression. Significantly, it has been observed that with age and certain disease states, DNA methylation status can become disrupted. For instance, a broad array of cancers are associated with promoter-specific hypermethylation and concomitant gene silencing. This review highlights that hypermethylation, and gene silencing, of the EN1 gene promoter, a crucial homeobox gene, has been detected in various forms of cancer. This has led to this region being proposed as a potential biomarker for diseases such as cancer. We conclude the review by describing a recently developed novel electrochemical method that can be used to quantify the level of methylation within the EN1 promoter and emphasise the growing trend in the use of electrochemical techniques for the detection of aberrant DNA methylation.