Cancer genetics of epigenetic genes

Natural bioactive compounds targeting DNA methyltransferase enzymes in cancer: Mechanisms insights and efficiencies

The regulation of gene expression is fundamental to health and life and is essentially carried out at the promoter region of the DNA of each gene. Depending on the molecular context, this region may be accessible or non-accessible (possibility of integration of RNA polymerase or not at this region). Among enzymes that control this process, DNA methyltransferase enzymes (DNMTs), are responsible for DNA demethylation at the CpG islands, particularly at the promoter regions, to regulate transcription. The aberrant activity of these enzymes, i.e. their abnormal expression or activity, can result in the repression or overactivation of gene expression. Consequently, this can generate cellular dysregulation leading to instability and tumor development. Several reports highlighted the involvement of DNMTs in human cancers. The inhibition or activation of DNMTs is a promising therapeutic approach in many human cancers. In the present work, we provide a comprehensive and critical summary of natural bioactive molecules as primary inhibitors of DNMTs in human cancers. The active compounds hold the potential to be developed as anti-cancer epidrugs targeting DNMTs.

Epigenetic alterations fuel brain metastasis via regulating inflammatory cascade

Brain metastasis (BrM) is a major threat to the survival of melanoma, breast, and lung cancer patients. Circulating tumor cells (CTCs) cross the blood-brain barrier (BBB) and sustain in the brain microenvironment. Genetic mutations and epigenetic modifications have been found to be critical in controlling key aspects of cancer metastasis. Metastasizing cells confront inflammation and gradually adapt in the unique brain microenvironment. Currently, it is one of the major areas that has gained momentum. Researchers are interested in the factors that modulate neuroinflammation during BrM. We review here various epigenetic factors and mechanisms modulating neuroinflammation and how this helps CTCs to adapt and survive in the brain microenvironment. Since epigenetic changes could be modulated by targeting enzymes such as histone/DNA methyltransferase, deacetylases, acetyltransferases, and demethylases, we also summarize our current understanding of potential drugs targeting various aspects of epigenetic regulation in BrM.

Patient-derived organoids identify tailored therapeutic options and determinants of plasticity in sarcomatoid urothelial bladder cancer

Sarcomatoid Urothelial Bladder Cancer (SARC) is a rare and aggressive histological subtype of bladder cancer for which therapeutic options are limited and experimental models are lacking. Here, we report the establishment of a long-term 3D organoid-like model derived from a SARC patient (SarBC-01). SarBC-01 emulates aggressive morphological, phenotypical, and transcriptional features of SARC and harbors somatic mutations in genes frequently altered in sarcomatoid tumors such as TP53 (p53) and RB1 (pRB). High-throughput drug screening, using a library comprising 1567 compounds in SarBC-01 and conventional urothelial carcinoma (UroCa) organoids, identified drug candidates active against SARC cells exclusively, or UroCa cells exclusively, or both. Among those, standard-of-care chemotherapeutic drugs inhibited both SARC and UroCa cells, while a subset of targeted drugs was specifically effective in SARC cells, including agents targeting the Glucocorticoid Receptor (GR) pathway. In two independent patient cohorts and in organoid models, GR and its encoding gene NR3C1 were found to be significantly more expressed in SARC as compared to UroCa, suggesting that high GR expression is a hallmark of SARC tumors. Further, glucocorticoid treatment impaired the mesenchymal morphology, abrogated the invasive ability of SARC cells, and led to transcriptomic changes associated with reversion of epithelial-to-mesenchymal transition, at single-cell level. Altogether, our study highlights the power of organoids for precision oncology and for providing key insights into factors driving rare tumor entities.

Epigenetic Modulations for Prevention of Infectious Diseases in Shrimp Aquaculture

Aquaculture assumes a pivotal role in meeting the escalating global food demand, and shrimp farming, in particular, holds a significant role in the global economy and food security, providing a rich source of nutrients for human consumption. Nonetheless, the industry faces formidable challenges, primarily attributed to disease outbreaks and the diminishing efficacy of conventional disease management approaches, such as antibiotic usage. Consequently, there is an urgent imperative to explore alternative strategies to ensure the sustainability of the industry. In this context, the field of epigenetics emerges as a promising avenue for combating infectious diseases in shrimp aquaculture. Epigenetic modulations entail chemical alterations in DNA and proteins, orchestrating gene expression patterns without modifying the underlying DNA sequence through DNA methylation, histone modifications, and non-coding RNA molecules. Utilizing epigenetic mechanisms presents an opportunity to enhance immune gene expression and bolster disease resistance in shrimp, thereby contributing to disease management strategies and optimizing shrimp health and productivity. Additionally, the concept of epigenetic inheritability in marine animals holds immense potential for the future of the shrimp farming industry. To this end, this comprehensive review thoroughly explores the dynamics of epigenetic modulations in shrimp aquaculture, with a particular emphasis on its pivotal role in disease management. It conveys the significance of harnessing advantageous epigenetic changes to ensure the long-term viability of shrimp farming while deliberating on the potential consequences of these interventions. Overall, this appraisal highlights the promising trajectory of epigenetic applications, propelling the field toward strengthening sustainability in shrimp aquaculture.

The Interplay between T Cells and Cancer: The Basis of Immunotherapy

Over the past decade, immunotherapy has emerged as one of the most promising approaches to cancer treatment. The use of immune checkpoint inhibitors has resulted in impressive and durable clinical responses in the treatment of various cancers. Additionally, immunotherapy utilizing chimeric antigen receptor (CAR)-engineered T cells has produced robust responses in blood cancers, and T cell receptor (TCR)-engineered T cells are showing promising results in the treatment of solid cancers. Despite these noteworthy advancements in cancer immunotherapy, numerous challenges remain. Some patient populations are unresponsive to immune checkpoint inhibitor therapy, and CAR T cell therapy has yet to show efficacy against solid cancers. In this review, we first discuss the significant role that T cells play in the body's defense against cancer. We then delve into the mechanisms behind the current challenges facing immunotherapy, starting with T cell exhaustion due to immune checkpoint upregulation and changes in the transcriptional and epigenetic landscapes of dysfunctional T cells. We then discuss cancer-cell-intrinsic characteristics, including molecular alterations in cancer cells and the immunosuppressive nature of the tumor microenvironment (TME), which collectively facilitate tumor cell proliferation, survival, metastasis, and immune evasion. Finally, we examine recent advancements in cancer immunotherapy, with a specific emphasis on T-cell-based treatments.

Characterizing crosstalk in epigenetic signaling to understand disease physiology

Epigenetics, the inheritance of genomic information independent of DNA sequence, controls the interpretation of extracellular and intracellular signals in cell homeostasis, proliferation and differentiation. On the chromatin level, signal transduction leads to changes in epigenetic marks, such as histone post-translational modifications (PTMs), DNA methylation and chromatin accessibility to regulate gene expression. Crosstalk between different epigenetic mechanisms, such as that between histone PTMs and DNA methylation, leads to an intricate network of chromatin-binding proteins where pre-existing epigenetic marks promote or inhibit the writing of new marks. The recent technical advances in mass spectrometry (MS) -based proteomic methods and in genome-wide DNA sequencing approaches have broadened our understanding of epigenetic networks greatly. However, further development and wider application of these methods is vital in developing treatments for disorders and pathologies that are driven by epigenetic dysregulation.

Epigenetic reprogramming in pancreatic premalignancy and clinical implications

Pancreatic cancer (PC) is the most lethal human cancer, with less than 10% 5-year survival. Pancreatic premalignancy is a genetic and epigenomic disease and is linked to PC initiation. Pancreatic premalignant lesions include pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN), with pancreatic acinar-to-ductal metaplasia (ADM) as the major source of pancreatic premalignant lesions. Emerging evidence reveals that an epigenetic dysregulation is an early event in pancreatic tumorigenesis. The molecular mechanisms of epigenetic inheritance include chromatin remodeling; modifications in histone, DNA, and RNA; non-coding RNA expression; and alternative splicing of RNA. Changes in those epigenetic modifications contribute to the most notable alterations in chromatin structure and promoter accessibility, thus leading to the silence of tumor suppressor genes and/or activation of oncogenes. The expression profiles of various epigenetic molecules provide a promising opportunity for biomarker development for early diagnosis of PC and novel targeted treatment strategies. However, how the alterations in epigenetic regulatory machinery regulate epigenetic reprogramming in pancreatic premalignant lesions and the different stages of their initiation needs further investigation. This review will summarize the current knowledge of epigenetic reprogramming in pancreatic premalignant initiation and progression, and its clinical applications as detection and diagnostic biomarkers and therapeutic targets in PC.

mRNA expression and epigenetic-based role of chromodomain helicase DNA-binding 5 in hepatocellular carcinoma

Objective

Chromodomain helicase DNA-binding 5 (CHD5) acts as a tumor suppressor gene in some cancers. CHD5 expression levels may affect an individual’s susceptibility to hepatocellular carcinoma (HCC). This study aimed to evaluate the methylation pattern of the CHD5 promoter region and the gene’s corresponding mRNA expression in HCC patients compared with healthy individuals.

Methods

In this case–control study, CHD5 mRNA gene expression levels and DNA methylation patterns were analyzed in 81 HCC patients and 90 healthy individuals by quantitative reverse transcription polymerase chain reaction and methylation-specific polymerase chain reaction, respectively.

Results

The CHD5 gene was hypermethylated in 61.8% of the HCC patients and 54.4% of the controls, and this difference was statistically significant. The CHD5 mRNA expression levels were significantly lower in the HCC patient group.

Conclusions

Hypermethylation of the CHD5 promoter region may significantly lower the expression of this gene, affecting the incidence and severity of HCC. The methylation status of CHD5 can also be further studied as a prognostic factor in HCC.

miRNAs Copy Number Variations Repertoire as Hallmark Indicator of Cancer Species Predisposition

Aging is one of the hallmarks of multiple human diseases, including cancer. We hypothesized that variations in the number of copies (CNVs) of specific genes may protect some long-living organisms theoretically more susceptible to tumorigenesis from the onset of cancer. Based on the statistical comparison of gene copy numbers within the genomes of both cancer-prone and -resistant species, we identified novel gene targets linked to tumor predisposition, such as CD52, SAT1 and SUMO. Moreover, considering their genome-wide copy number landscape, we discovered that microRNAs (miRNAs) are among the most significant gene families enriched for cancer progression and predisposition. Through bioinformatics analyses, we identified several alterations in miRNAs copy number patterns, involving miR-221, miR-222, miR-21, miR-372, miR-30b, miR-30d and miR-31, among others. Therefore, our analyses provide the first evidence that an altered miRNAs copy number signature can statistically discriminate species more susceptible to cancer from those that are tumor resistant, paving the way for further investigations.

Epi-miRNAs: Regulators of the Histone Modification Machinery in Human Cancer

Cancer is a leading cause of death and disability worldwide. Epigenetic deregulation is one of the most critical mechanisms in carcinogenesis and can be classified into effects on DNA methylation and histone modification. MicroRNAs are small noncoding RNAs involved in fine-tuning their target genes after transcription. Various microRNAs control the expression of histone modifiers and are involved in a variety of cancers. Therefore, overexpression or downregulation of microRNAs can alter cell fate and cause malignancies. In this review, we discuss the role of microRNAs in regulating the histone modification machinery in various cancers, with a focus on the histone-modifying enzymes such as acetylases, deacetylases, methyltransferases, demethylases, kinases, phosphatases, desumoylases, ubiquitinases, and deubiquitinases. Understanding of microRNA-related aberrations underlying histone modifiers in pathogenesis of different cancers can help identify novel therapeutic targets or early detection approaches that allow better management of patients or monitoring of treatment response.

Gasdermin E-mediated programmed cell death: An unpaved path to tumor suppression

Hearing loss-associated protein gasdermin E (GSDME), an effector of secondary necrosis, has been identified in a new pathway of programmed cell death (PCD). GSDME epigenetic silencing and mutations resulting in loss-of-function have been reported in cancer tissues. Additionally, GSDME upregulation inhibits tumor proliferation as well as colony forming ability, and reduces the incidence of lymphatic metastasis, demonstrating that GSDME may act as a tumor suppressor. Here, we have focused on the molecular mechanisms of GSDME-mediated PCD, and tried to reveal the crosstalk between this cell death pathway and apoptosis, autophagy, GSDMD-mediated pyroptosis. Moreover, we concluded the anti-cancer activity of GSDME include forming permeable membranes, and triggering anti-cancer immunity. Thus, GSDME was potential to be a novel target for cancer prevention and treatment.

A Chemo-Genomic Approach Identifies Diverse Epigenetic Therapeutic Vulnerabilities in MYCN-Amplified Neuroblastoma

Although a rare disease, neuroblastoma accounts for the highest proportion of childhood cancer deaths. There is a lack of recurrent somatic mutations in neuroblastoma embryonal tumours, suggesting a possible role for epigenetic alterations in driving this cancer. While an increasing number of reports suggest an association of MYCN with epigenetic machinery, the mechanisms of these interactions are poorly understood in the neuroblastoma setting. Utilising chemo-genomic approaches we revealed global MYCN-epigenetic interactions and identified numerous epigenetic proteins as MYCN targets. The epigenetic regulators HDAC2, CBX8 and CBP (CREBBP) were all MYCN target genes and also putative MYCN interactors. MYCN-related epigenetic genes included SMARCs, HDACs, SMYDs, BRDs and CREBBP. Expression levels of the majority of MYCN-related epigenetic genes showed predictive ability for neuroblastoma patient outcome. Furthermore, a compound library screen targeting epigenetic proteins revealed broad susceptibility of neuroblastoma cells to all classes of epigenetic regulators, belonging to families of bromodomains, HDACs, HATs, histone methyltransferases, DNA methyltransferases and lysin demethylases. Ninety-six percent of the compounds reduced MYCN-amplified neuroblastoma cell viability. We show that the C646 (CBP-bromodomain targeting compound) exhibits switch-like temporal and dose response behaviour and is effective at reducing neuroblastoma viability. Responsiveness correlates with MYCN expression, with MYCN-amplified cells being more susceptible to C646 treatment. Thus, exploiting the broad vulnerability of neuroblastoma cells to epigenetic targeting compounds represents an exciting strategy in neuroblastoma treatment, particularly for high-risk MYCN-amplified tumours.

Targeting DNA methyltransferases in non-small-cell lung cancer

Despite the advances in treatment using chemotherapy or targeted therapies, due to static survival rates, non-small cell lung cancer (NSCLC) is the major cause of cancer-related deaths worldwide. Epigenetic-based therapies have been developed for NSCLC by targeting DNA methyltransferases (DNMTs) and histone-modifying enzymes. However, treatment using single epigenetic agents on solid tumours has been inadequate; whereas, treatment with a combination of DNMTs inhibitors with chemotherapy and immunotherapy has shown great promise. Dietary sources of phytochemicals could also inhibit DNMTs and cancer stem cells, representing a novel and promising way to prevent and treat cancer. Herein, we will discuss the different DNMTs, DNA methylation profiling in NSCLC as well as current demethylating agents in ongoing clinical trials. Therefore, providing a concise overview of future developments in the field of epigenetic therapy in NSCLC.

Regulation of alternative polyadenylation in the yeast Saccharomyces cerevisiae by histone H3K4 and H3K36 methyltransferases

Adjusting DNA structure via epigenetic modifications, and altering polyadenylation (pA) sites at which precursor mRNA is cleaved and polyadenylated, allows cells to quickly respond to environmental stress. Since polyadenylation occurs co-transcriptionally, and specific patterns of nucleosome positioning and chromatin modifications correlate with pA site usage, epigenetic factors potentially affect alternative polyadenylation (APA). We report that the histone H3K4 methyltransferase Set1, and the histone H3K36 methyltransferase Set2, control choice of pA site in Saccharomyces cerevisiae, a powerful model for studying evolutionarily conserved eukaryotic processes. Deletion of SET1 or SET2 causes an increase in serine-2 phosphorylation within the C-terminal domain of RNA polymerase II (RNAP II) and in the recruitment of the cleavage/polyadenylation complex, both of which could cause the observed switch in pA site usage. Chemical inhibition of TOR signaling, which causes nutritional stress, results in Set1- and Set2-dependent APA. In addition, Set1 and Set2 decrease efficiency of using single pA sites, and control nucleosome occupancy around pA sites. Overall, our study suggests that the methyltransferases Set1 and Set2 regulate APA induced by nutritional stress, affect the RNAP II C-terminal domain phosphorylation at Ser2, and control recruitment of the 3′ end processing machinery to the vicinity of pA sites.

Impairment of DYRK2 by DNMT1‑mediated transcription augments carcinogenesis in human colorectal cancer

Dual specificity tyrosine‑phosphorylation‑regulated kinase 2 (DYRK2) is a protein kinase that functions as a novel tumor suppressor. Previous studies have reported that DYRK2 expression is decreased in colorectal cancer compared with adjacent non‑tumor tissues. However, the regulatory mechanisms by which the expression of DYRK2 is diminished remain unknown. The aim of the present study was to determine the regulatory mechanisms of DYRK2 expression. The present study identified the promoter regions of the DYRK2 gene and demonstrated that they contained CpG islands in human cancer cells. In addition, the DYRK2 promoter region exhibited a higher level of methylation in colorectal cancer tissues compared with healthy tissues from clinical samples. DYRK2 expression was increased at the mRNA and protein level in colorectal cancer cell lines by treatment with 5‑Azacytidine, a demethylating agent. The results further demonstrated that knockdown of DNA methyltransferase (DNMT) 1 elevated DYRK2 expression in colorectal cancer cell lines. A colitis‑related mouse carcinogenesis model also exhibited a lower DYRK2 level in colorectal cancer tissues compared with adjacent non‑tumor tissues. In this model, nuclear staining of DNMT1 was detected in colorectal cancer cells, whereas a cytoplastic distribution pattern of DNMT1 staining was exhibited in healthy tissue. Overall, these findings suggested that DYRK2 expression was downregulated via transcriptional regulation by DNMT1 to elevate the proliferation of colorectal cancer cells.

Curcumin effect on cancer cells' multidrug resistance: An update

Chemotherapy is one of the main methods for cancer treatment. However, despite many advances in the design of anticancer drugs, their efficiency is limited due to their high toxicity and resistance of cells to chemotherapeutic drugs. In order to improve the cancer therapy, it is essential to use the compounds that can overcome drug resistance and increase treatment efficiency. Researchers have studied the effects of natural compounds for the controlling various drug resistance mechanisms. Curcumin is a natural phenolic compound which shows potent anticancer activities in different tumors, alone or as an adjuvant with other antitumor drugs to prevent or inhibit the survival and cancer progression by various mechanisms. The role of curcumin in overcoming drug resistance was followed by reviewing different applications of curcumin in cancer therapy. Afterward, the clinical impacts of curcumin, role of curcumin in decreasing drug resistance in different cancer cells and its mechanisms were discussed. It has been demonstrated that curcumin regulates signaling pathways in cancer cells, reduces the expression of proteins related to drug resistance, and increases the performance of antitumor drugs at various levels. Curcumin reverses multidrug resistance mechanisms and increases sensitivity of resistance cells to chemotherapy. This review mainly focuses on different mechanisms of drug resistance and curcumin as a nontoxic natural substance to eliminate the effects of drug resistance through modulation and controlling cell resistance pathways and eventually suggests curcumin as a potent chemosensitizer in cancers.

Overexpression of MECP2 attenuates cigarette smoke extracts induced lung epithelial cell injury by promoting CYP1B1 methylation

MECP2 (Methyl-CpG-binding protein 2) has been shown to have a critical role in regulating DNA methylation against smoke exposed lung injury. However, the biological function of MECP2 and the underlying molecular mechanism remains elusive. Human bronchial epithelial (16HBE) and alveolar type II epithelial cells (AECII) were exposed to increasing concentrations of cigarette smoke extracts (CSE) solution to establish CSE-induced lung epithelial cell injury models. Our findings revealed that MECP2 was down-regulated, while CYP1B1 was up-regulated in CSE-induced lung epithelial cell injury models by quantitative real time PCR, western blotting and immunofluorescence staining. Down-regulated CYP1B1 was ascribed to the demethylation of its promoter by methylation-specific PCR (MSP). The in vitro experiments further showed that MECP2 overexpression significantly attenuated CSE-triggered cell growth attenuation, cell cycle arrest, apoptosis and ROS generation in lung epithelial cells by CCK-8 and flow cytometry assays. In molecular level, we further demonstrated that MECP2 overexpression obviously suppressed the expression of CYP1B1 through enhancing DNA methylation. Therefore, our data suggest that MECP2 protects against CSE-induced lung epithelial cell injury possibly through down-regulating CYP1B1 expression via elevating its methylation status.

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.

Correlation between a variable number tandem repeat (VNTR) polymorphism in SMYD3 gene and breast cancer: A genotype-phenotype study

Genetic predisposition to breast cancer (BC) has become one of the most studied aspects of the disease. Advances in the field of cancer research have revealed the role of different genetic polymorphisms within genes of interest in the development of BC. This study aimed to explore the impact of a variable number tandem repeat (VNTR) genetic variant found within the SET and MYND domain containing protein 3 (SMYD3) gene on BC risk in Jordan and examine key clinical and pathological prognostic factors. Genotyping of blood samples from 180 cases with breast cancer and 180 healthy individuals from the Jordanian population was carried out via a combination of PCR and agarose gel electrophoresis. A highly significant association was found at level of genotype (P-value = 0.009) and allele (P-value = 0.0001) between BC development and the VNTR variant in the SMYD3 gene among Jordanian women. Moreover, we found that the VNTR of SMYD3 gene may interfere with BC risk among patients with different immunohistochemistry (IHC) profiles (P-value < 0.05). This study reported that there is a significant correlation between BC development and the VNTR in the SMYD3 gene. These findings can help alleviate the burden of BC in developing countries including Jordan and to fill the gaps in current literature. Since this study was carried out on Jordanian Arabs, more studies on the link between BC and the SMYD3 VNTR variant are recommended to determine this polymorphism's impact on other ethnic groups.

Study of KMT2B (MLL2) gene expression changes in patients with breast cancer

Aim: This study aimed to demonstrate misregulation of KMT2B gene expression in breast cancer tissue. Materials & methods: Cancerous and marginal tissue samples were collected from 43 female patients. After RNA extraction and cDNA synthesis, quantitative-PCR was used to evaluate the expression level of the KMT2B gene. REST, Sigma plot and SPSS software were used to analyze data. Results: KMT2B gene expression was significantly decreased in tumor tissue compared with marginal tissue (p = 0.02). No significant correlation was found between expression levels of KMT2B and clinical parameters of patients (p > 0.05) Conclusion: Our study demonstrated that downregulation of KMT2B is associated with breast cancer and its misregulation may play an important role in tumorigenesis.

Local delivery of arsenic trioxide nanoparticles for hepatocellular carcinoma treatment

Hepatocellular carcinoma (HCC) is a malignancy with a poor prognosis. Surgery combined with chemotherapy has been recommended as a curative regimen for HCC. Nevertheless, the anticancer mechanisms of chemicals in hepatocellular carcinoma remain unclear. Pyroptosis is a type of programmed necrosis, and its mechanism in hepatocellular carcinoma is poorly understood. The efficacy and mechanism of arsenic trioxide nanoparticles in the treatment of HCC were explored in this research. Arsenic trioxide alone and arsenic trioxide nanoparticles were conveniently administered to mice intratumorally using a needle. Compared with As2O3, As2O3 nanoparticles (As2O3-NPs) showed better inhibition, promoted greater LDH release, and induced cell morphology indicative of pyroptosis in vitro. Compared with the free drug, As2O3-NPs increased GSDME-N expression and decreased Dnmt3a, Dnmt3b, and Dnmt1 expression in Huh7 cells. In vivo, As2O3-NPs induced a significant decrease in the expression of Dnmt3a, Dnmt3b and Dnmt1, but significantly upregulated the expression of GSDME-N (gasdermin E (GSDME) was originally found to be related to deafness; recently, it has been defined as a gasdermin family member associated with pyroptosis). As2O3-NPs inhibited tumor growth more strongly than As2O3 or control, a finding likely attributed to the downregulation of PCNA and DNMT-related proteins and the upregulation of GSDME-N.

DNMT3a promotes proliferation by activating the STAT3 signaling pathway and depressing apoptosis in pancreatic cancer

Background

Although aberrant DNA methyltransferase 3a (DNMT3a) expression is important to the tumorigenesis of pancreatic ductal adenocarcinoma (PDAC), the role of DNMT3a in PDAC prognosis is not clarified yet due to the limited studies and lacking of underlying molecular mechanism.

Methods

The expression of DNMT3a was examined by immunohistochemistry in PDAC tissues. Gene expression profiles assays were conducted to explore the impact of DNMT3a on biological processes and signal pathways. Cell cycle and apoptosis were measured by flow cytometry. Western blotting and real-time qPCR assays were used to explore the impact of DNMT3a on expression of protein and mRNA related to cell cycle, STAT3 signaling pathway and apoptosis.

Results

DNMT3a was overexpressed and closely associated with poor outcomes of PDAC. DNMT3a knockdown restrained PDAC cell proliferation, induced cell cycle arrest and promoted apoptosis in vitro. Affymetrix GeneChip Human Transcriptome Array identified that the cell cycle-related process was most significantly associated with DNMT3a. DNMT3a knockdown induced G1-S phase transition arrest by decreasing the expression of cyclin D1, which was mediated by the reduction of IL8 and the subsequent inactivation of STAT3 signaling pathway. Furthermore, exogenous apoptosis was also promoted after DNMT3a knockdown, probably via up-regulation of DNA transcription and expression in CASP8.

Conclusion

These findings indicate that DNMT3a plays an important role in PDAC progression. DNMT3a may serve as a prognostic biomarker and a therapeutic strategy candidate in PDAC.

Investigating the structural features of chromodomain proteins in the human genome and predictive impacts of their mutations in cancers

Epigenetic readers are specific proteins which recognize histone marks and represents the underlying mechanism for chromatin regulation. Histone H3 lysine methylation is a potential epigenetic code for the chromatin organization and transcriptional control. Recognition of histone methylation is achieved by evolutionary conserved reader modules known as chromodomain, identified in several proteins, and is involved in transcriptional silencing and chromatin remodelling. Genetic perturbations within the structurally conserved chromodomain could potentially mistarget the reader protein and impair their regulatory pathways, ultimately leading to cellular chaos by setting the stage for tumor development and progression. Here, we report the structural conservations associated with diverse functions, prognostic significance and functional consequences of mutations within chromodomain of human proteins in distinct cancers. We have extensively analysed chromodomain containing human proteins in terms of their structural-functional ability to act as a molecular switch in the recognition of methyl-lysine recognition. We further investigated the combinatorial potential, target promiscuity and binding specificity associated with their underlying mechanisms. Indeed, the molecular mechanism of epigenetic silencing significantly underlies a newer cancer therapy approach. We hope that a critical understanding of chromodomains will pave the way for novel paths of research providing newer insights into the designing of effective anti-cancer therapies.

Reduction in H3K4me patterns due to aberrant expression of methyltransferases and demethylases in renal cell carcinoma: prognostic and therapeutic implications

Renal cell carcinoma (RCC) is the leading cause among cancer-related deaths due to urological cancers, which results in response to combination of genetic and epigenetic factors. Histone methylations have been implicated in renal tumorigenesis but their clinical significance and underlying pathology are unexplored. Here, we elucidated the histone 3 lysine 4 (H3K4) methylation patterns in clear cell RCC and its underlying pathology. Lower cellular levels of H3K4 mono-methylation, -dimethylation and -tri-methylation were fraternized with higher TNM staging and Fuhrman grading as well as tumor metastasis. Further, the expression profile of 20 H3K4 modifiers revealed the significant over-expression of histone demethylases compared to methyltransferases, indicating their role in the reduction of H3K4 methylation levels. In view of above facts, the role of LSD2 and KDM5A demethylases in RCC pathogenesis were explored using respective siRNAs. The RCC cells exhibited reduced cell viability after knockdown of LSD2 and KDM5A genes with concomitant induction of apoptosis. In addition, propidium iodide staining demonstrated an arrest of RCC cells at S-phase and sub-G1 phase of the cell cycle. Taken together, these observations provide new pathological insights behind the alterations of H3K4 methylation patterns in ccRCC with their prognostic and therapeutic implications.

Targeting Mybbp1a suppresses HCC progression via inhibiting IGF1/AKT pathway by CpG islands hypo-methylation dependent promotion of IGFBP5

BACKGROUND

Myb-binding protein 1A (Mybbp1a) is a nucleolar protein that can regulate rRNA metabolism, the stress response and carcinogenesis. However, the function of Mybbp1a in the progression of hepatocellular carcinoma (HCC) is unclear. We aimed to determine the role of Mybbp1a in HCC and the underlying mechanism.

METHODS

We investigated the function of Mybbp1a in HCC cell models and the xenograft mouse model. The relationship between Mybbp1a and IGFBP5 was found through expression profile chip. The molecular mechanism of Mybbp1a regulating IGFBP5 was proved through CO-IP, CHIP, Bisulfite Sequencing and Pyrosequencing.

FINDINGS

In this study, we observed that Mybbp1a was overexpressed in HCC tissues and associated with the poor prognosis of HCC patients. Suppression of Mybbp1a led to a reduction in the proliferation and migration ability of HCC cells through inhibiting the IGF1/AKT signaling pathway. Further study found that Mybbp1a could form a complex with DNMT1 and induce aberrant hyper-methylation of CpG islands of IGFBP5, which inhibits secretion of IGFBP5 and then activates IGF1/AKT signaling pathway.

INTERPRETATION

These findings extend our understanding of the function of Mybbp1a in the progression of HCC. The newly identified Mybbp1a may provide a novel biomarker for developing potential therapeutic targets of HCC. FUND: Science Technology Department of Zhejiang Province (No. 2015C03034), National Health and Family Planning Commission of China (No. 2016138643), Innovative Research Groups of National Natural Science Foundation of China (No. 81721091), Major program of National Natural Science Foundation of China (No. 91542205).

Epigenetic regulation of RET receptor tyrosine kinase and non-coding RNAs in MTC

Medullary thyroid carcinoma (MTC) is an aggressive and rare cancer with limited treatment options for metastatic disease. Due to this, there is a need for a better understanding of MTC biology in the hope of improved treatments. One area of improved understanding of cancer biology is epigenetics. Epigenetics is defined as cellular processes which alter gene expression independent of changes in the primary DNA sequence. These processes include modifications such as DNA methylation, microRNA deregulation and post-translational histone modifications, all of which have been implicated in tumorigenesis of MTC. Transcription of the main driver of MTC - the REarranged during Transfection (RET) proto-oncogene can also be modulated by epigenetic alterations. This review will present a review of MTC and its epigenetic links with a particular focus on targeting epigenetic mechanisms as novel therapeutic strategies.

Serum glycine dehydrogenase is associated with increased risk of lung cancer and promotes malignant transformation by regulating DNA methyltransferases expression

Identification of novel risk factors that are critical to the initiation of lung cancer will be key for its prevention. Recently, it has been reported that glycine dehydrogenase (GLDC) can drive the formation of lung cancer initiating cells. However, there have been no perspective studies on the association between circulating GLDC and lung cancer until now. To identify whether serum GLDC is a risk factor for lung cancer, the present study conducted a nested case‑control study within a Chinese cohort. Using ELISAs, serum GLDC was measured in 300 case subjects, who were subsequently diagnosed with lung cancer during follow‑up, and in 600 matched healthy controls. The results revealed that serum GLDC was associated with increased lung cancer risk [odds ratio=1.48; 95% confidence intervals (1.01‑2.04)]. Spearman correlation was employed to analyze the associations between age, body mass index, years of smoking and the serum concentration of GLDC. It was demonstrated that years of smoking was associated with serum GLDC (spearman's correlation, ρ=0.81) in patients with lung cancer. However, the association was attenuated in the serum of matched controls (ρ=0.48). In addition, overexpression of GLDC protein contributed to malignant transformation and inhibited microRNA (miR)‑29 family expression in normal human bronchial epithelial (NHBE) cells. Aberrant methylation of tumor suppressive gene (TSG) is an early event in the development of lung cancer, which is controlled by DNA methyltransferases (DNMTs). The present study demonstrated that GLDC promoted the expression of DNMT proteins; however, the miR‑29 family inhibited their expression in NHBE cells. Thus, it was concluded that elevated serum GLDC may increase lung cancer risk, and that smoking, GLDC, the miR‑29 family and DNMT signaling pathways may serve an important role in early malignant transformation during the development of lung cancer.

Epimutation and Cancer: Carcinogenesis Viewed as Error-Prone Inheritance of Epigenetic Information

The epimutation concept, that is, malignancy is a result of deranged patterns of gene expression due to defective epigenetic control, proposes that in the majority of adult cancers the primary (initiating) lesion adversely affects the mechanism of vertical transmission of the epigenetic pattern existing in the stem cells of differentiated tissue. Such an error-prone mechanism will result in deviant gene expression capable of accumulation at each mitosis of the affected stem cell clone. It is argued that a proportion of these proliferation products will express combinations of genes which endow them with malignant properties, such as the ability to transgress tissue boundaries and migrate to distant locations. Since the likelihood of this occurrence is dependent on the proliferation of cells manifesting the defective epigenetic transmission, the theory predicts that cancer incidence will be strongly influenced by factors regulating the turnover rate of the stem cells of the tissue in question. Evidence relating to this stipulation is examined. In addition, it would be anticipated on the basis of the selection of genes involved that the susceptibility to malignant transformation will vary according to the tissue of origin and this is also discussed.

An epigenetic regulator-related score (EpiScore) predicts survival in patients with diffuse large B cell lymphoma and identifies patients who may benefit from epigenetic therapy

Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma and shows considerable clinical and biological heterogeneity. Much research is currently focused on the identification of prognostic markers for more specific patients’ risk stratification and on the development of therapeutic approaches to improve the long-term outcome. Epigenetic alterations are involved in various cancers, including lymphoma. Interestingly, epigenetic alterations are reversible and drugs to target some of them have been developed. In this study, we demonstrated that the gene expression profile of epigenetic regulators has a prognostic value in DLBCL and identified pathways that could be involved in DLBCL poor outcome. We then designed a new risk score (EpiScore) based on the gene expression level of the epigenetic regulators DNMT3A, DOT1L, SETD8. EpiScore was predictive of overall survival in DLBCL and allowed splitting patients with DLBCL from two independent cohorts (n = 414 and n = 69) in three groups (high, intermediate and low risk). EpiScore was an independent predictor of survival when compared with previously described prognostic factors, such as the International Prognostic Index (IPI), germinal center B cell and activated B cell molecular subgroups, gene expression-based risk score (GERS) and DNA repair score. Immunohistochemistry analysis of DNMT3A in 31 DLBCL samples showed that DNMT3A overexpression (>42% of positive tumor cells) correlated with reduced overall and event-free survival. Finally, an HDAC gene signature was significantly enriched in the DLBCL samples included in the EpiScore high-risk group. We conclude that EpiScore identifies high-risk patients with DLBCL who could benefit from epigenetic therapy.

SET oncoprotein accumulation regulates transcription through DNA demethylation and histone hypoacetylation

Epigenetic modifications are essential in the control of normal cellular processes and cancer development. DNA methylation and histone acetylation are major epigenetic modifications involved in gene transcription and abnormal events driving the oncogenic process. SET protein accumulates in many cancer types, including head and neck squamous cell carcinoma (HNSCC); SET is a member of the INHAT complex that inhibits gene transcription associating with histones and preventing their acetylation. We explored how SET protein accumulation impacts on the regulation of gene expression, focusing on DNA methylation and histone acetylation. DNA methylation profile of 24 tumour suppressors evidenced that SET accumulation decreased DNA methylation in association with loss of 5-methylcytidine, formation of 5-hydroxymethylcytosine and increased TET1 levels, indicating an active DNA demethylation mechanism. However, the expression of some suppressor genes was lowered in cells with high SET levels, suggesting that loss of methylation is not the main mechanism modulating gene expression. SET accumulation also downregulated the expression of 32 genes of a panel of 84 transcription factors, and SET directly interacted with chromatin at the promoter of the downregulated genes, decreasing histone acetylation. Gene expression analysis after cell treatment with 5-aza-2′-deoxycytidine (5-AZA) and Trichostatin A (TSA) revealed that histone acetylation reversed transcription repression promoted by SET. These results suggest a new function for SET in the regulation of chromatin dynamics. In addition, TSA diminished both SET protein levels and SET capability to bind to gene promoter, suggesting that administration of epigenetic modifier agents could be efficient to reverse SET phenotype in cancer.

Rpb9-deficient cells are defective in DNA damage response and require histone H3 acetylation for survival

Rpb9 is a non-essential subunit of RNA polymerase II that is involved in DNA transcription and repair. In budding yeast, deletion of RPB9 causes several phenotypes such as slow growth and temperature sensitivity. We found that simultaneous mutation of multiple N-terminal lysines within histone H3 was lethal in rpb9Δ cells. Our results indicate that hypoacetylation of H3 leads to inefficient repair of DNA double-strand breaks, while activation of the DNA damage checkpoint regulators γH2A and Rad53 is suppressed in Rpb9-deficient cells. Combination of H3 hypoacetylation with the loss of Rpb9 leads to genomic instability, aberrant segregation of chromosomes in mitosis, and eventually to cell death. These results indicate that H3 acetylation becomes essential for efficient DNA repair and cell survival if a DNA damage checkpoint is defective.

Reduction in promotor methylation utilizing EGCG (epigallocatechin-3-gallate) restores RXRα expression in human colon cancer cells

Silencing of regulatory genes through hypermethylation of CpG islands is an important mechanism in tumorigenesis. In colon cancer, RXRα, an important dimerization partner with other nuclear transcription factors, is silenced through this mechanism. We previously found that colon tumors in Apc^Min/+ mice had diminished levels of RXRα protein and expression levels of this gene were restored by treatment with a green tea intervention, due to reduced promoter methylation of RXRα. We hypothesized that CIMP+ cell lines, which epigenetically silence key regulatory genes would also evidence silencing of RXRα and EGCG treatment would restore its expression. We indeed found EGCG to restore RXRα activity levels in the human cell lines, in a dose dependent manner and reduced RXRα promoter methylation. EGCG induced methylation changes in several other colon cancer related genes but did not cause a decrease in global methylation. Numerous epidemiological reports have shown the benefits of green tea consumption in reducing colon cancer risk but to date no studies have shown that the risk reduction may be related to the epigenetic restoration by tea polyphenols. Our results show that EGCG modulates the reversal of gene silencing involved in colon carcinogenesis providing a possible avenue for colon cancer prevention and treatment.

CpG Islands in Cancer: Heads, Tails, and Sides

DNA methylation is a dynamic epigenetic mark that characterizes different cellular developmental stages, including tissue-specific profiles. This CpG dinucleotide modification cooperates in the regulation of the output of the cellular genetic content, in both healthy and pathological conditions. According to endogenous and exogenous stimuli, DNA methylation is involved in gene transcription, alternative splicing, imprinting, X-chromosome inactivation, and control of transposable elements. When these dinucleotides are organized in dense regions are called CpG islands (CGIs), being commonly known as transcriptional regulatory regions frequently associated with the promoter region of several genes. In cancer, promoter DNA hypermethylation events sustained the mechanistic hypothesis of epigenetic transcriptional silencing of an increasing number of tumor suppressor genes. CGI hypomethylation-mediated reactivation of oncogenes was also documented in several cancer types. In this chapter, we aim to summarize the functional consequences of the differential DNA methylation at CpG dinucleotides in cancer, focused in CGIs. Interestingly, cancer methylome is being recently explored, looking for biomarkers for diagnosis, prognosis, and predictors of drug response.

Therapeutical potential of deregulated lysine methyltransferase SMYD3 as a safe target for novel anticancer agents

INTRODUCTION

SET and MYND domain containing-3 (SMYD3) is a member of the lysine methyltransferase family of proteins, and plays an important role in the methylation of various histone and non-histone targets. Proper functioning of SMYD3 is very important for the target molecules to determine their different roles in chromatin remodeling, signal transduction and cell cycle control. Due to the abnormal expression of SMYD3 in tumors, it is projected as a prognostic marker in various solid cancers. Areas covered: Here we elaborate on the general information, structure and the pathological role of SMYD3 protein. We summarize the role of SMYD3-mediated protein interactions in oncology pathways, mutational effects and regulation of SMYD3 in specific types of cancer. The efficacy and mechanisms of action of currently available SMYD3 small molecule inhibitors are also addressed. Expert opinion: The findings analyzed herein demonstrate that aberrant levels of SMYD3 protein exert tumorigenic effects by altering the epigenetic regulation of target genes. The partial involvement of SMYD3 in some distinct pathways provides a vital opportunity in targeting cancer effectively with fewer side effects. Further, identification and co-targeting of synergistic oncogenic pathways is suggested, which could provide much more beneficial effects for the treatment of solid cancers.

Integrating Epigenomics into the Understanding of Biomedical Insight

Epigenetics is one of the most rapidly expanding fields in biomedical research, and the popularity of the high-throughput next-generation sequencing (NGS) highlights the accelerating speed of epigenomics discovery over the past decade. Epigenetics studies the heritable phenotypes resulting from chromatin changes but without alteration on DNA sequence. Epigenetic factors and their interactive network regulate almost all of the fundamental biological procedures, and incorrect epigenetic information may lead to complex diseases. A comprehensive understanding of epigenetic mechanisms, their interactions, and alterations in health and diseases genome widely has become a priority in biological research. Bioinformatics is expected to make a remarkable contribution for this purpose, especially in processing and interpreting the large-scale NGS datasets. In this review, we introduce the epigenetics pioneering achievements in health status and complex diseases; next, we give a systematic review of the epigenomics data generation, summarize public resources and integrative analysis approaches, and finally outline the challenges and future directions in computational epigenomics.

Structure and dynamics of H. pylori 98-10 C5-cytosine specific DNA methyltransferase in complex with S-adenosyl-l-methionine and DNA

Helicobacter pylori is a Gram-negative bacterium that inhabits the human gastrointestinal tract, and some strains of this bacterium cause gastric ulcers and cancer. DNA methyltransferases (MTases) are promising drug targets for the treatment of cancer and other diseases that are also caused by epigenetic alternations of the genome. The C5-cytosine specific DNA methyltransferase from H. pylori (M. Hpy C5mC) catalyzes the transfer of the methyl group from the cofactor S-adenosyl-l-methionine (AdoMet) to the flipped cytosine of the substrate DNA. Herein we report the sequence analyses, 3-D structure modeling and molecular dynamics simulations of M. Hpy C5mC, when complexed with AdoMet as well as DNA. We analyzed the protein-DNA interactions prominently established by the flipped cytosine and the interactions between the protein and cofactor in the active site. We propose that the contacts made by cytosine O2 with Arg155 and Arg157, and the water-mediated interactions with cytosine N3 may be essential for the activity of methyl transfer as well as the deprotonation at the C5 position in our C5mC model. Specific recognition of DNA was mediated mainly by residues from Ser221-Arg229 and Ser243-Gln246 of the target recognition domain (TRD) and some residues of the loop Ser75-Lys83 from the large domain. These findings are further supported by alanine scanning mutagenesis studies. The results reported here explain the sequence, structure and binding features necessary for the recognition between the cofactor and the substrate by the key epigenetic enzyme, M. Hpy C5mC.

A phase I trial of panobinostat (LBH589) in patients with metastatic melanoma

Epigenetic alterations by histone/protein deacetylases (HDACs) are one of the many mechanisms that cancer cells use to alter gene expression and promote growth. HDAC inhibitors have proven to be effective in the treatment of specific malignancies, particularly in combination with other anticancer agents. We conducted a phase I trial of panobinostat in patients with unresectable stage III or IV melanoma. Patients were treated with oral panobinostat at a dose of 30 mg daily on Mondays, Wednesdays, and Fridays (Arm A). Three of the six patients on this dose experienced clinically significant thrombocytopenia requiring dose interruption. Due to this, a second treatment arm was opened and the dose was changed to 30 mg oral panobinostat three times a week every other week (Arm B). Six patients were treated on Arm A and 10 patients were enrolled to Arm B with nine patients treated. In nine patients treated on Arm B, the response rate was 0% (90% confidence interval [CI]: 0–28%) and the disease‐control rate was 22% (90% CI: 4–55%). Among all 15 patients treated, the overall response rate was 0% (90% CI: 0–17%) and the disease‐control rate was 27% (90% CI: 10–51%). There was a high rate of toxicity associated with treatment. Correlative studies suggest the presence of immune modifications after HDAC inhibition. Panobinostat is not active as a single agent in the treatment of melanoma. Further exploration of this agent in combination with other therapies may be warranted.

Human papillomaviruses in epigenetic regulations

Human Papillomaviruses (HPVs) are double-stranded DNA viruses, that infect epithelial cells and are etiologically involved in the development of human cancer. Today, over 200 types of human papillomaviruses are known. They are divided into low-risk and high-risk HPVs depending on their potential to induce carcinogenesis, driven by two major viral oncoproteins, E6 and E7. By interacting with cellular partners, these proteins are involved in interdependent viral and cell cycles in stratified differentiating epithelium, and concomitantly induce epigenetic changes in infected cells and those undergoing malignant transformation. E6 and E7 oncoproteins interact with and/or modulate expression of many proteins involved in epigenetic regulation, including DNA methyltransferases, histone-modifying enzymes and subunits of chromatin remodeling complexes, thereby influencing host cell transcription program. Furthermore, HPV oncoproteins modulate expression of cellular micro RNAs. Most of these epigenetic actions in a complex dynamic interplay participate in the maintenance of persistent infection, cell transformation, and development of invasive cancer by a considerable deregulation of tumor suppressor and oncogenes. In this study, we have undertaken to discuss a number of studies concerning epigenetic regulations in HPV-dependent cells and to focus on those that have biological relevance to cancer progression.

The interplay between the lysine demethylase KDM1A and DNA methyltransferases in cancer cells is cell cycle dependent

DNA methylation and histone modifications are key epigenetic regulators of gene expression, and tight connections are known between the two. DNA methyltransferases are upregulated in several tumors and aberrant DNA methylation profiles are a cancer hallmark. On the other hand, histone demethylases are upregulated in cancer cells. Previous work on ES cells has shown that the lysine demethylase KDM1A binds to DNMT1, thereby affecting DNA methylation. In cancer cells, the occurrence of this interaction has not been explored. Here we demonstrate in several tumor cell lines an interaction between KDM1A and both DNMT1 and DNMT3B. Intriguingly and in contrast to what is observed in ES cells, KDM1A depletion in cancer cells was found not to trigger any reduction in the DNMT1 or DNMT3B protein level or any change in DNA methylation. In the S-phase, furthermore, KDM1A and DNMT1 were found, to co-localize within the heterochromatin. Using P-LISA, we revealed substantially increased binding of KDM1A to DNMT1 during the S-phase. Together, our findings propose a mechanistic link between KDM1A and DNA methyltransferases in cancer cells and suggest that the KDM1A/DNMT1 interaction may play a role during replication. Our work also strengthens the idea that DNMTs can exert functions unrelated to act on DNA methylation.

Epigenetic Determinants of Cancer

SUMMARYEpigenetic changes are present in all human cancers and are now known to cooperate with genetic alterations to drive the cancer phenotype. These changes involve DNA methylation, histone modifiers and readers, chromatin remodelers, microRNAs, and other components of chromatin. Cancer genetics and epigenetics are inextricably linked in generating the malignant phenotype; epigenetic changes can cause mutations in genes, and, conversely, mutations are frequently observed in genes that modify the epigenome. Epigenetic therapies, in which the goal is to reverse these changes, are now one standard of care for a preleukemic disorder and form of lymphoma. The application of epigenetic therapies in the treatment of solid tumors is also emerging as a viable therapeutic route.

miRNA regulation of Sirtuin-1 expression in human astrocytoma

Sirtuins are a family of 7 histone deacetylases largely involved in the regulation of cell proliferation, survival and death. The role of sirtuins in tumorigenesis and cancer progression has been previously studied in certain cancer types. Few studies have investigated sirtuin expression in gliomas, with controversial results. The aim of the present study was to investigate the expression of sirtuin-1 (Sirt-1) in diffuse astrocytoma [low grade astrocytoma (LGA)], anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) and in primary glioma cell lines: PLGAC (primary LGA cells); PAAC (primary AA cells); and PGBMC (primary GBM cells). Tumor samples were obtained from patients who underwent craniotomy for microsurgical tumor resection at the Neurosurgery Unit of the University of Messina between 2011 and 2014. Sirt-1 expression was qualitatively analyzed in 30 human glial tumor samples and 5 non-neoplastic brain tissue (NBT) specimens using immunohistochemistry and western blotting techniques. Sirt-1 expression was quantitatively analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, Sirt-1 expression in primary cell lines was investigated by immunoblotting and RT-qPCR. Sirt-1 expression was downregulated in gliomas compared to NBTs. Sirt-1 levels also varied among different tumor grades, with more evident downregulation in high-grade (P<0.001) than low-grade tumors (P<0.01). These data were confirmed in cell lines, with the exception of upregulation of protein level in the highest malignancy grade cell lines. The present results suggest a role for miRNA-34a, miRNA-132 and miRNA-217 in the epigenetic control of Sirt-1 during gliomagenesis and progression, and demonstrate the different implications of Sirt-1 in human tissues and cell lines. Furthermore, the present results reveal that Sirt-1 may be an intrinsic regulator of tumor progression and the regulation of Sirt-1 involves complex molecular pathways. However, the biological functions of Sirt-1 in gliomagenesis require additional investigation.

Turning on the Radio: Epigenetic Inhibitors as Potential Radiopriming Agents

First introduced during the late 1800s, radiation therapy is fundamental to the treatment of cancer. In developed countries, approximately 60% of all patients receive radiation therapy (also known as the sixty percenters), which makes radioresistance in cancer an important and, to date, unsolved, clinical problem. Unfortunately, the therapeutic refractoriness of solid tumors is the rule not the exception, and the ubiquity of resistance also extends to standard chemotherapy, molecularly targeted therapy and immunotherapy. Based on extrapolation from recent clinical inroads with epigenetic agents to prime refractory tumors for maximum sensitivity to concurrent or subsequent therapies, the radioresistant phenotype is potentially reversible, since aberrant epigenetic mechanisms are critical contributors to the evolution of resistant subpopulations of malignant cells. Within the framework of a syllogism, this review explores the emerging link between epigenetics and the development of radioresistance and makes the case that a strategy of pre- or co-treatment with epigenetic agents has the potential to, not only derepress inappropriately silenced genes, but also increase reactive oxygen species production, resulting in the restoration of radiosensitivity.

SMYD3 contributes to a more aggressive phenotype of prostate cancer and targets Cyclin D2 through H4K20me3

Prostate cancer (PCa) is one of the most incident cancers worldwide but clinical and pathological parameters have limited ability to discriminate between clinically significant and indolent PCa. Altered expression of histone methyltransferases and histone methylation patterns are involved in prostate carcinogenesis. SMYD3 transcript levels have prognostic value and discriminate among PCa with different clinical aggressiveness, so we decided to investigate its putative oncogenic role on PCa.

We silenced SMYD3 and assess its impact through in vitro (cell viability, cell cycle, apoptosis, migration, invasion assays) and in vivo (tumor formation, angiogenesis). We evaluated SET domain's impact in PCa cells' phenotype. Histone marks deposition on SMYD3 putative target genes was assessed by ChIP analysis.

Knockdown of SMYD3 attenuated malignant phenotype of LNCaP and PC3 cell lines. Deletions affecting the SET domain showed phenotypic impact similar to SMYD3 silencing, suggesting that tumorigenic effect is mediated through its histone methyltransferase activity. Moreover, CCND2 was identified as a putative target gene for SMYD3 transcriptional regulation, through trimethylation of H4K20.

Our results support a proto-oncogenic role for SMYD3 in prostate carcinogenesis, mainly due to its methyltransferase enzymatic activity. Thus, SMYD3 overexpression is a potential biomarker for clinically aggressive disease and an attractive therapeutic target in PCa.