Inhibition of enhancer of zeste homolog 2 (EZH2) expression is associated with decreased tumor cell proliferation, migration, and invasion in endometrial cancer cell lines

EZH2 regulates pancreatic cancer cells through E2F1, GLI1, CDK3, and Mcm4

Pancreatic cancer (PC) is one of the most common malignant tumors in digestive tract. To explore the role of epigenetic factor EZH2 in the malignant proliferation of PC, so as to provide effective medical help in PC. Sixty paraffin sections of PC were collected and the expression of EZH2 in PC tissues was detected by immunohistochemical assay. Three normal pancreas tissue samples were used as controls. The regulation of EZH2 gene on proliferation and migration of normal pancreatic cell and PC cell were determined by MTS, colony forming, Ki-67 antibody, scratch and Transwell assays. Through differential gene annotation and differential gene signaling pathway analysis, differentially expressed genes related to cell proliferation were selected and verified by RT-qPCR. EZH2 is mainly expressed in the nuclei of pancreatic tumor cells, but not in normal pancreatic cells. The results of cell function experiments showed that EZH2 overexpression could enhance the proliferation and migration ability of PC cell BXPC-3. Cell proliferation ability increased by 38% compared to the control group. EZH2 knockdown resulted in reduced proliferation and migration ability of cells. Compared with control, proliferation ability of cells reduced by 16%-40%. The results of bioinformatics analysis of transcriptome data and RT-qPCR demonstrated that EZH2 could regulate the expression of E2F1, GLI1, CDK3 and Mcm4 in normal and PC cells. The results revealed that EZH2 might regulate the proliferation of normal pancreatic cell and PC cell through E2F1, GLI1, CDK3 and Mcm4.

Resistance to BRAF Inhibitors: EZH2 and Its Downstream Targets as Potential Therapeutic Options in Melanoma

Activating BRAF mutations occurs in 50-60% of malignant melanomas. Although initially treatable, the development of resistance to BRAF-targeted therapies (BRAFi) is a major challenge and limits their efficacy. We have previously shown that the BRAF_V600E signaling pathway mediates the expression of EZH2, an epigenetic regulator related to melanoma progression and worse overall survival. Therefore, we wondered whether inhibition of EZH2 would be a way to overcome resistance to vemurafenib. We found that the addition of an EZH2 inhibitor to vemurafenib improved the response of melanoma cells resistant to BRAFi with regard to decreased viability, cell-cycle arrest and increased apoptosis. By next-generation sequencing, we revealed that the combined inhibition of BRAF and EZH2 dramatically suppresses pathways of mitosis and cell cycle. This effect was linked to the downregulation of Polo-kinase 1 (PLK1), a key regulator of cell cycle and proliferation. Subsequently, when we inhibited PLK1, we found decreased cell viability of melanoma cells resistant to BRAFi. When we inhibited both BRAF and PLK1, we achieved an improved response of BRAFi-resistant melanoma cells, which was comparable to the combined inhibition of BRAF and EZH2. These results thus reveal that targeting EZH2 or its downstream targets, such as PLK1, in combination with BRAF inhibitors are potential novel therapeutic options in melanomas with BRAF mutations.

Role of EZH2 in Uterine Gland Development

Enhancer of zeste homolog 2 (EZH2) is a core component of polycomb repressive complex 2 that plays a vital role in transcriptional repression of gene expression. Conditional ablation of EZH2 using progesterone receptor (Pgr)-Cre in the mouse uterus has uncovered its roles in regulating uterine epithelial cell growth and stratification, suppressing decidual myofibroblast activation, and maintaining normal female fertility. However, it is unclear whether EZH2 plays a role in the development of uterine glands, which are required for pregnancy success. Herein, we created mice with conditional deletion of Ezh2 using anti-Mullerian hormone receptor type 2 (Amhr2)-Cre recombinase that is expressed in mesenchyme-derived cells of the female reproductive tract. Strikingly, these mice showed marked defects in uterine adenogenesis. Unlike Ezh2 Pgr-Cre conditional knockout mice, deletion of Ezh2 using Amhr2-Cre did not lead to the differentiation of basal-like cells in the uterus. The deficient uterine adenogenesis was accompanied by impaired uterine function and pregnancy loss. Transcriptomic profiling using next generation sequencing revealed dysregulation of genes associated with signaling pathways that play fundamental roles in development and disease. In summary, this study has identified an unrecognized role of EZH2 in uterine gland development, a postnatal event critical for pregnancy success and female fertility.

SWI/SNF Antagonism of PRC2 Mediates Estrogen-Induced Progesterone Receptor Expression

Endometrial cancer (EC) is characterized by high estrogen levels unopposed by progesterone. Treatment with progestins is standard for early EC, but the response to progestins is dependent on progesterone receptor (PGR) expression. Here, we show that the expression of PGR in endometrial epithelial cells is dependent on ARID1A, a DNA-binding subunit of the SWI/SNF chromatin-remodeling complex that is commonly mutated in EC. In endometrial epithelial cells with estrogen receptor overexpression, we find that ARID1A promotes estrogen signaling and regulates common gene expression programs. Normally, endometrial epithelial cells expressing estrogen receptors respond to estrogen by upregulating the PGR. However, when ARID1A expression is lost, upregulation of PGR expression is significantly reduced. This phenomenon can also occur following the loss of the SWI/SNF subunit BRG1, suggesting a role for ARID1A- and BRG1-containing complexes in PGR regulation. We find that PGR is regulated by a bivalent promoter, which harbors both H3K4me3 and H3K27me3 histone tail modifications. H3K27me3 is deposited by EZH2, and inhibition of EZH2 in the context of ARID1A loss results in restoration of estrogen-induced PGR expression. Our results suggest a role for ARID1A deficiency in the loss of PGR in late-stage EC and a therapeutic utility for EZH2 inhibitors in this disease.

TCF3 is epigenetically silenced by EZH2 and DNMT3B and functions as a tumor suppressor in endometrial cancer

Endometrial cancer (EC) is the most common gynecological malignancy worldwide. However, the molecular mechanisms underlying EC progression are still largely unknown, and chemotherapeutic options for EC patients are currently very limited. In this study, we found that histone methyltransferase EZH2 and DNA methyltransferase DNMT3B were upregulated in EC samples from patients, and promoted EC cell proliferation as evidenced by assays of cell viability, cell cycle, colony formation. Mechanistically, we found that EZH2 promoted EC cell proliferation by epigenetically repressing TCF3, a direct transcriptional activator of CCKN1A (p21WAF1/Cip1), in vitro and in vivo. In addition, we found that DNMT3B specifically methylated the TCF3 promoter, repressing TCF3 expression and accelerating EC cell proliferation independently of EZH2. Importantly, elevated expression of EZH2 or DNMT3B in EC patients inversely correlated with expression of TCF3 and p21, and was associated with shorter overall survival. We show that combined treatment with GSK126 and 5-Aza-2d treatment wit synergistically inhibited methyltransferase activity of EZH2 and DNMT3B, resulting in a profound block of EC cell proliferation as well as EC tumor progression in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models. These findings reveal that TCF3 functions as a tumor suppressor epigenetically silenced by EZH2 and DNMT3B in EC, and support the notion that targeting the EZH2/DNMT3B/TCF3/p21 axis may be a novel and effective therapeutic strategy for treatment of EC.

Spatial Transcriptomics analysis of uterine gene expression in enhancer of Zeste homolog 2 (Ezh2) conditional knockout mice

Histone proteins undergo various modifications that alter chromatin structure, including addition of methyl groups. Enhancer of homolog 2 (EZH2), is a histone methyltransferase that methylates lysine residue 27, and thereby, suppresses gene expression. EZH2 plays integral role in the uterus and other reproductive organs. We have previously shown that conditional deletion of uterine EZH2 results in increased proliferation of luminal and glandular epithelial cells, and RNAseq analyses reveal several uterine transcriptomic changes in Ezh2 conditional (c) knockout (KO) mice that can affect estrogen signaling pathways. To pinpoint the origin of such gene expression changes, we used the recently developed spatial transcriptomics (ST) method with the hypotheses that Ezh2cKO mice would predominantly demonstrate changes in epithelial cells and/or ablation of this gene would disrupt normal epithelial/stromal gene expression patterns. Uteri were collected from ovariectomized adult WT and Ezh2cKO mice and analyzed by ST. Asb4, Cxcl14, Dio2, and Igfbp5 were increased, Sult1d1, Mt3, and Lcn2 were reduced in Ezh2cKO uterine epithelium vs. WT epithelium. For Ezh2cKO uterine stroma, differentially expressed key hub genes included Cald1, Fbln1, Myh11, Acta2, and Tagln. Conditional loss of uterine Ezh2 also appears to shift the balance of gene expression profiles in epithelial vs. stromal tissue toward uterine epithelial cell and gland development and proliferation, consistent with uterine gland hyperplasia in these mice. Current findings provide further insight into how EZH2 may selectively affect uterine epithelial and stromal compartments. Additionally, these transcriptome data might provide the mechanistic understanding and valuable biomarkers for human endometrial disorders with epigenetic underpinnings.

Bimodal regulation of the PRC2 complex by USP7 underlies tumorigenesis

Although overexpression of EZH2, a catalytic subunit of the polycomb repressive complex 2 (PRC2), is an eminent feature of various cancers, the regulation of its abundance and function remains insufficiently understood. We report here that the PRC2 complex is physically associated with ubiquitin-specific protease USP7 in cancer cells where USP7 acts to deubiquitinate and stabilize EZH2. Interestingly, we found that USP7-catalyzed H2BK120ub1 deubiquitination is a prerequisite for chromatin loading of PRC2 thus H3K27 trimethylation, and this process is not affected by H2AK119 ubiquitination catalyzed by PRC1. Genome-wide analysis of the transcriptional targets of the USP7/PRC2 complex identified a cohort of genes including FOXO1 that are involved in cell growth and proliferation. We demonstrated that the USP7/PRC2 complex drives cancer cell proliferation and tumorigenesis in vitro and in vivo. We showed that the expression of both USP7 and EZH2 elevates during tumor progression, corresponding to a diminished FOXO1 expression, and the level of the expression of USP7 and EZH2 strongly correlates with histological grades and prognosis of tumor patients. These results reveal a dual role for USP7 in the regulation of the abundance and function of EZH2, supporting the pursuit of USP7 as a therapeutic target for cancer intervention.

The long noncoding RNA TUNAR modulates Wnt signaling and regulates human β-cell proliferation

Many long noncoding RNAs (lncRNAs) are enriched in pancreatic islets and several lncRNAs are linked to type 2 diabetes (T2D). Although they have emerged as potential players in β-cell biology and T2D, little is known about their functions and mechanisms in human β-cells. We identified an islet-enriched lncRNA, TUNAR (TCL1 upstream neural differentiation-associated RNA), which was upregulated in β-cells of patients with T2D and promoted human β-cell proliferation via fine-tuning of the Wnt pathway. TUNAR was upregulated following Wnt agonism by a glycogen synthase kinase-3 (GSK3) inhibitor in human β-cells. Reciprocally, TUNAR repressed a Wnt antagonist Dickkopf-related protein 3 (DKK3) and stimulated Wnt pathway signaling. DKK3 was aberrantly expressed in β-cells of patients with T2D and displayed a synchronized regulatory pattern with TUNAR at the single cell level. Mechanistically, DKK3 expression was suppressed by the repressive histone modifier enhancer of zeste homolog 2 (EZH2). TUNAR interacted with EZH2 in β-cells and facilitated EZH2-mediated suppression of DKK3. These findings reveal a novel cell-specific epigenetic mechanism via islet-enriched lncRNA that fine-tunes the Wnt pathway and subsequently human β-cell proliferation.NEW & NOTEWORTHY The discovery that long noncoding RNA TUNAR regulates β-cell proliferation may be important in designing new treatments for diabetes.

Targeting Epigenetic Regulators for Endometrial Cancer Therapy: Its Molecular Biology and Potential Clinical Applications

Endometrial cancer is one of the most frequently diagnosed gynecological malignancies worldwide. However, its prognosis in advanced stages is poor, and there are only few available treatment options when it recurs. Epigenetic changes in gene function, such as DNA methylation, histone modification, and non-coding RNA, have been studied for the last two decades. Epigenetic dysregulation is often reported in the development and progression of various cancers. Recently, epigenetic changes in endometrial cancer have also been discussed. In this review, we give the main points of the role of DNA methylation and histone modification in endometrial cancer, the diagnostic tools to determine these modifications, and inhibitors targeting epigenetic regulators that are currently in preclinical studies and clinical trials.

CYP27B1 Downregulation: A New Molecular Mechanism Regulating EZH2 in Ovarian Cancer Tumorigenicity

Background

Ovarian cancer has the highest mortality rate among gynecologic cancers, and most patients are diagnosed in advanced stages. Enhancer of zeste homolog 2 (EZH2) is a major tumor marker and an effective therapeutic target for ovarian cancer, but the underlying molecular mechanism remains unclear. The present study investigated the biological effects of EZH2 knockout in SKOV3 cells in vitro and in vivo and explored the molecular mechanism by integrated analysis of messenger RNA sequencing (mRNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) data.

Methods

The CRISPR/Cas9 system was used to establish EZH2 knockout SKOV3 cells. Protein expression was evaluated by Western blotting. The effect of EZH2 on ovarian cancer was evaluated in vitro with MTT, wound healing, Transwell, and apoptosis assays and in vivo with a xenograft model. mRNA-seq and ChIP-seq were performed to explore the molecular mechanism underlying the biological function of EZH2. Immunohistochemical staining (IHC) of tissue arrays was used to analyze the correlations among EZH2 and CYP27B1 expressions and prognosis.

Results

We obtained three EZH2 knockout subclones. EZH2 knockout SKOV3 cells exhibited significantly suppressed proliferation, migration, and invasion and a significantly increased apoptosis rate. The subcutaneous tumor formation rate decreased from 100 to 0% in the EZH2 knockout group. Integrated analysis of the mRNA-seq and ChIP-seq data identified 1,455 significantly upregulated genes with matching downregulated trimethylation of histone H3 lysine 27 (H3K27me3) methylation binding sites in 1b11H cells compared to SKOV3 cells. The set of downregulated genes in EZH2 knockout cells was highly enriched in genes regulating the activation of steroid biosynthesis; the top-ranked hub gene was CYP27B1. The EZH2 and CYP27B1 expression levels showed a statistically significant inverse correlation, which was also associated with unfavorable prognosis. The in vitro experiment demonstrated that CYP27B1 can suppress the proliferation, migration, and invasion of ovarian cancer cells. Moreover, the levels of AKT and p-AKT were significantly increased, whereas STAT3 was downregulated, in 1b11H cells compared to SKOV3 cells. Moreover, STAT3 and AKT overexpression was observed in 1b11H siRNA for CYP27B1 (siCYP27B1) cells.

Conclusion

EZH2 plays an important role in promoting cell proliferation, migration, and invasion in ovarian cancer by regulating the core steroid biosynthesis gene via H3K27me3 methylation. Moreover, CYP27B1, the steroid biosynthesis hub gene, might be a novel therapeutic target for ovarian cancer.

Antihistamine Drug Ebastine Inhibits Cancer Growth by Targeting Polycomb Group Protein EZH2

Enhancer of zester homolog 2 (EZH2), a histone lysine methyltransferase and the catalytic component of polycomb repressive complex 2, has been extensively investigated as a chromatin regulator and a transcriptional suppressor by methylating H3 at lysine 27 (H3K27). EZH2 is upregulated or mutated in most cancers, and its expression levels are negatively associated with clinical outcomes. However, the current developed small-molecule inhibitors targeting EZH2 enzymatic activities could not inhibit the growth and progression of solid tumors. Here, we discovered an antihistamine drug, ebastine, as a novel EZH2 inhibitor by targeting EZH2 transcription and subsequently downregulating EZH2 protein level and H3K27 trimethylation in multiple cancer cell lines at concentrations below 10 μmol/L. The inhibition of EZH2 by ebastine further impaired the progression, migration, and invasiveness of these cancer cells. Overexpression of Ezh2 wild-type and its mutant, H689A (lacking methyltransferase activity), rescued the neoplastic properties of these cancer cells after ebastine treatment, suggesting that EZH2 targeted by ebastine is independent of its enzymatic function. Next-generation RNA-sequencing analysis also revealed that C4-2 cells treated with 8 μmol/L ebastine showed a gene profiling pattern similar to EZH2-knockdown C4-2 cells, which was distinctively different from cells treated with GSK126, an EZH2 enzyme inhibitor. In addition, ebastine treatment effectively reduced tumor growth and progression, and enhanced progression-free survival in triple-negative breast cancer and drug-resistant castration-resistant prostate cancer patient-derived xenograft mice. Our data demonstrated that ebastine is a novel, safe, and potent anticancer agent for patients with advanced cancer by targeting the oncoprotein EZH2.

Investigating the Role of Telomere and Telomerase Associated Genes and Proteins in Endometrial Cancer

Endometrial cancer (EC) is the commonest gynaecological malignancy. Current prognostic markers are inadequate to accurately predict patient survival, necessitating novel prognostic markers, to improve treatment strategies. Telomerase has a unique role within the endometrium, whilst aberrant telomerase activity is a hallmark of many cancers. The aim of the current in silico study is to investigate the role of telomere and telomerase associated genes and proteins (TTAGPs) in EC to identify potential prognostic markers and therapeutic targets. Analysis of RNA-seq data from The Cancer Genome Atlas identified differentially expressed genes (DEGs) in EC (568 TTAGPs out of 3467) and ascertained DEGs associated with histological subtypes, higher grade endometrioid tumours and late stage EC. Functional analysis demonstrated that DEGs were predominantly involved in cell cycle regulation, while the survival analysis identified 69 DEGs associated with prognosis. The protein-protein interaction network constructed facilitated the identification of hub genes, enriched transcription factor binding sites and drugs that may target the network. Thus, our in silico methods distinguished many critical genes associated with telomere maintenance that were previously unknown to contribute to EC carcinogenesis and prognosis, including NOP56, WFS1, ANAPC4 and TUBB4A. Probing the prognostic and therapeutic utility of these novel TTAGP markers will form an exciting basis for future research.

The Roles of the Histone Protein Modifier EZH2 in the Uterus and Placenta

Epigenetic modifications regulate normal physiological, as well as pathological processes in various organs, including the uterus and placenta. Both organs undergo dramatic and rapid restructuring that depends upon precise orchestration of events. Epigenetic changes that alter transcription and translation of gene-sets regulate such responses. Histone modifications alter the chromatin structure, thereby affecting transcription factor access to gene promoter regions. Binding of histones to DNA is regulated by addition or removal of subunit methyl and other groups, which can inhibit or stimulate transcription. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of polycomb repressive complex 2 (PRC2) that catalyzes tri-methylation of histone H3 at Lys 27 (H3K27me3) and subsequently suppresses transcription of genes bound by such histones. Uterine EZH2 expression exerts a critical role in development and function of this organ with deletion of this gene resulting in uterine hyperplasia and expression of cancer-associated transcripts. Elucidating the roles of EZH2 in uterus and placenta is essential as EZH2 dysregulation is associated with several uterine and placental pathologies. Herein, we discuss EZH2 functions in uterus and placenta, emphasizing its physiological and pathological importance.

Histone methyltransferase and drug resistance in cancers

A number of novel anticancer drugs have been developed in recent years. However, the mortality of cancer patients remains high because of the emergence of drug resistance. It was reported that drug resistance might involved in changes in gene expression without changing genotypes, which is similar to epigenetic modification. Some studies indicated that targeting histone methyltransferase can reverse drug resistance. Hence, the use of histone methyltransferase inhibitors or histone demethylase inhibitors opens new therapeutic approaches for cancer treatment. While the relationship between histone methyltransferase and tumor resistance has been determined, there is a lack of updated review on the association between them. In this review, we summarized the mechanisms of histone methyltransferases in cancer drug resistance and the therapeutic strategies of targeting histone methyltransferase to reverse drug resistance.

The Emerging Roles of Heterochromatin in Cell Migration

Cell migration is a key process in health and disease. In the last decade an increasing attention is given to chromatin organization in migrating cells. In various types of cells induction of migration leads to a global increase in heterochromatin levels. Heterochromatin is required for optimal cell migration capabilities, since various interventions with heterochromatin formation impeded the migration rate of numerous cell types. Heterochromatin supports the migration process by affecting both the mechanical properties of the nucleus as well as the genetic processes taking place within it. Increased heterochromatin levels elevate nuclear rigidity in a manner that allows faster cell migration in 3D environments. Condensed chromatin and a more rigid nucleus may increase nuclear durability to shear stress and prevent DNA damage during the migration process. In addition, heterochromatin reorganization in migrating cells is important for induction of migration-specific transcriptional plan together with inhibition of many other unnecessary transcriptional changes. Thus, chromatin organization appears to have a key role in the cellular migration process.

Identification of miRNA-mRNA Regulatory Network and Construction of Prognostic Signature in Cervical Cancer

Cervical cancer (CC) remains a most prevalent female cancer worldwide, but there are few biomarkers used in diagnosis and prognosis of CC. The aim of this study is to find reliable and effective biomarkers regarding CC development. Microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database to search potential miRNA-mRNA in CC. The gene ontology term enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were conducted to reveal the underlying functions and pathways of differently expressed genes (DEGs). Univariate Cox, multivariate Cox, and risk scoring methods were performed to identify a prognostic model. A total of 209 DEGs of CC were identified. In the protein-protein interaction network, hub module, and hub genes were recognized. Based on DEGs, three small molecules (thioguanosine, apigenin, and trichostatin A) were screened out as potential drugs. Two miRNAs (hsa-mir-101-3p and hsa-mir-6507-5p) and some transcription factors were found to be associated with prognosis of CC. A five-candidate gene signature (APOBEC3B, DSG2, CXCL8, ABCA8, and PLAGL1) was constructed to stratify risk subgroups for patients with CC. The risk score of the prognostic model was also found to be associated with immune cells infiltration, including mast cell activation, natural killer cells resting, dendritic cells resting, T cells regulatory (Tregs), and T cells follicular helper. The miRNA-mRNA regulatory network and the prognostic model are of great clinical significance in promoting prognosis prediction and treatment of CC.

Carcinogenic roles and therapeutic effects of EZH2 in gynecological cancers

Enhancer of Zeste Homolog 2 (EZH2) is highly expressed in kinds of malignant tumors and related to tumor occurrence, development, and prognosis. EZH2 is the catalytic subunit of the polycomb repressive complex 2 (PRC2), which promotes cell proliferation, migration, and invasion by epigenetic regulation of anti-tumor gene. It can activate numerous tumor-associated signaling pathways and interfere with DNA damage repair. In recent years, large amounts of studies have shown that EZH2 is closely related to gynecologic-related malignancies and can be used as a potential target gene for the treatment of gynecological-related malignancies. This review summarizes the oncogenic function of EZH2 and introduces the recent advances in the development of EZH2 inhibitors. On this basis, future research prospect of EZH2 is proposed.

Mice lacking uterine enhancer of zeste homolog 2 have transcriptomic changes associated with uterine epithelial proliferation

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that suppresses gene expression. Previously, we developed a conditional null model where EZH2 is knocked out in uterus. Deletion of uterine EZH2 increased proliferation of luminal and glandular epithelial cells. Herein, we used RNA-Seq in wild-type (WT) and EZH2 conditional knockout (Ezh2cKO) uteri to obtain mechanistic insights into the gene expression changes that underpin the pathogenesis observed in these mice. Ovariectomized adult Ezh2cKO mice were treated with vehicle (V) or 17β-estradiol (E2; 1 ng/g). Uteri were collected at postnatal day (PND) 75 for RNA-Seq or immunostaining for epithelial proliferation. Weighted gene coexpression network analysis was used to link uterine gene expression patterns and epithelial proliferation. In V-treated mice, 88 transcripts were differentially expressed (DEG) in Ezh2cKO mice, and Bmp5, Crabp2, Lgr5, and Sprr2f were upregulated. E2 treatment resulted in 40 DEG with Krt5, Krt15, Olig3, Crabp1, and Serpinb7 upregulated in Ezh2cKO compared with control mice. Transcript analysis relative to proliferation rates revealed two module eigengenes correlated with epithelial proliferation in WT V vs. Ezh2cKO V and WT E2 vs. Ezh2cKO E2 mice, with a positive relationship in the former and inverse in the latter. Notably, the ESR1, Wnt, and Hippo signaling pathways were among those functionally enriched in Ezh2cKO females. Current results reveal unique gene expression patterns in Ezh2cKO uterus and provide insight into how loss of this critical epigenetic regulator assumingly contributes to uterine abnormalities.

Overexpression of enhance of Zeste homolog 2 (EZH2) in endometrial carcinoma: An NRG Oncology/Gynecologic Oncology Group Study

OBJECTIVES

Enhancer of zeste homolog 2 (EZH2) is a histone methyl transferase that mediates epigenetic silencing of tumor suppressor genes. It is commonly over-expressed in several solid tumors and has been shown to be a prognostic biomarker. We investigated patterns of EZH2 expression in endometrial cancer.

METHODS

Evaluation of EZH2 expression was completed on both early and advanced stage endometrioid adenocarcinoma tissues and a subset of matched normal mullerian tissue samples, from participants enrolled in Gynecologic Oncology Group (GOG) protocol 210, using real time reverse transcription polymerase chain reaction (RT-PCR) and western blot (WB) analysis. Non-parametric methods were used to assess differences in mRNA and protein expression respectively with known clinical/pathologic prognostic factors. Survival analysis was performed using techniques including Cox proportional hazards (PH) model to evaluate differences in progression free survival (PFS) and overall survival (OS) based on EZH2 expression.

RESULTS

Eighty-seven patient samples were analyzed that included 60 tumors and 27 matched-normal tissue specimens. EZH2 mRNA (p < .0001) and protein expression (p < .0001) in tumor specimens were significantly higher than in matched-normal tissue. In primary tumors, EZH2 protein expression was associated with lympho-vascular space invasion (LVSI, p = .044), and EZH2 mRNA expression was associated with age (p = .037). Differences in EZH2 expression between primary tumors and matched normal tissue were not associated with other known clinical and pathologic factors. However, there did appear to be a trend toward decreased progression-free survival among patients with high EZH2 expression levels.

CONCLUSIONS

Our results confirm the differential expression of EZH2 in uterine cancers compared to normal tissues. However, there were no statistically significant differences in survival associated with EZH2 expression in patients with endometrial cancer. NCT #: NCT00340808.

LncRNA NEAT1 promotes endometrial cancer cell proliferation, migration and invasion by regulating the miR-144-3p/EZH2 axis

Background

Endometrial cancer (EC) is one of the most common gynaecological tumours in the worldwide. Long non-coding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) promotes cell proliferation, migration and invasion in EC cells. However, the molecular mechanisms of NEAT1 in EC have not been fully clarified. We conducted this study to reveal the function of NEAT1 in EC tissues and cell lines.

Materials and methods

Cancer and adjacent tissues were collected from EC patients. HEC-1A and Ishikawa cells were cultured in vitro. NEAT1 expression was downregulated by transfecting small hairpin RNA (shRNA) and miR-144-3p was overexpressed by transfecting miR-144-3p mimics. Cell proliferation was detected by MTT assay and colony formation assay. Cell migration and invasion abilities were assessed by transwell assay. A dual-luciferase reporter assay was used to verify the relationship among NEAT1, EZH2, and miR-144-3p. The expression level of EZH2 was measured by Western blot and qPCR.

Results

NEAT1 was highly expressed in EC tissues and cells. Knockdown of NEAT1 inhibited the proliferation, migration and invasion of EC cells. Additionally, NEAT1 acted as a ceRNA of miR-144-3p, leading to EZH2 upregulation. Overexpression of miR-144-3p suppressed the proliferation and invasion of EC cells.

Conclusions

NEAT1 promotes EC cells proliferation and invasion by regulating the miR-144-3p/EZH2 axis.

miR-137 is a tumor suppressor in endometrial cancer and is repressed by DNA hypermethylation

Endometrial cancer is the most common gynecological cancer in the United States. We wanted to identify epigenetic aberrations involving microRNAs (miRNAs), whose genes become hypermethylated in endometrial primary tumors. By integrating known miRNA sequences from the miRNA database (miRBase) with DNA methylation data from methyl-CpG-capture sequencing, we identified 111 differentially methylated regions (DMRs) associated with CpG islands (CGIs) and miRNAs. Among them, 22 DMRs related to 29 miRNAs and within 8 kb of CGIs were hypermethylated in endometrial tumors but not in normal endometrium. miR-137 was further validated in additional endometrial primary tumors. Hypermethylation of miR-137 was found in both endometrioid and serous endometrial cancer (P < 0.01), and it led to the loss of miR-137 expression. Treating hypermethylated endometrial cancer cells with epigenetic inhibitors reactivated miR-137. Moreover, genetic overexpression of miR-137 suppressed cancer cell proliferation and colony formation in vitro. When transfected cancer cells were implanted into nude mice, the cells that overexpressed miR-137 grew more slowly and formed smaller tumors (P < 0.05) than vector transfectants. Histologically, xenograft tumors from cancer cells expressing miR-137 were less proliferative (P < 0.05), partly due to inhibition of EZH2 and LSD1 expression (P < 0.01) in both the transfected cancer cells and tumors. Reporter assays indicated that miR-137 targets EZH2 and LSD1. These results suggest that miR-137 is a tumor suppressor that is repressed in endometrial cancer because the promoter of its gene becomes hypermethylated.

MicroRNA-365 targets multiple oncogenes to inhibit proliferation, invasion, and self-renewal of aggressive endometrial cancer cells

Background

MicroRNA-365 (miR-365) has been reported to be a tumor suppressor miRNA. However, the role of miR-365 in progression of endometrial cancer (EC) has not been explored, in this study, we have found that re-expression of miRNA-365 inhibits cell proliferation, causes apoptosis and senescence.

Materials and methods

Overexpression of miR-365 attenuated cell migration and invasion, inhibited sphere-forming capacity, and enhanced the chemosensitivity to paclitaxel. In silico prediction tools identified the potential targets of miR-365.

Results

We identified EZH2 and FOS as targets of miR-365 and found that downregulating these genes imitated the tumor suppressive effect of miR-365. The outcomes of the study suggested that a reverse correlation existed between low miR-365 and overexpression of FOS and EZH2 in EC tissue specimens.

Conclusion

The study concludes that miR-365 acts as an important tumor suppressor and contributes by suppressing cell invasiveness, proliferation, and self-renewal in cancer cell lines by regulating multiple oncogenes. We establish that miR-365-EZH2/FOS pathway is an important target for treating EC.

Oxidative stress and cell cycle arrest induced by short-term exposure to dustfall PM2.5 in A549 cells

It was reported that in vitro short-term exposure to PM_2.5 caused different lung diseases through inflammatory response, immune toxicity, oxidative stress, and genetic mutations. However, the complex molecular biological mechanism for its toxicity had not been fully elucidated. Therefore, the present study investigated the cytotoxicity, oxidative damage, mitochondria damage, apoptosis, and cell cycle arrest of NX and QH PM_2.5 in A549 cells. Further, cell cycle arrest-related gene levels in PM_2.5-induced A549 cells were also detected. Our results suggested that PM_2.5 reduced the cell viability in A549 cells. Simultaneously, excessive ROS decreased MMP levels and damaged mitochondrial membrane integrity and induced mitochondrial oxidative damage through the oxygen-dependent killer route, resulting in mitochondrial damage and cell apoptosis. Besides, the results also showed that PM_2.5 induced A549 cell cycle alteration in G2/M phase after co-culture for 24 h. G2/M phase arrest was induced by upregulation of p53 and p21 and downregulation of CDK1 mRNA expression. In addition, lncRNA Sox2ot might play an important role as the specific oncogenes and it participated in G2/M phase arrest by regulating the expression of EZH₂.

Anti-tumor and anti-metastasis activities of honey bee larvae powder by suppressing the expression of EZH2

Honey bee larvae products have been widely used as traditional daily supplements and complementary medicine for health promotion. However, there is little scientific evidence about their bioactivities. This study was designed to examine the anti-tumor and anti-metastasis effects of honey bee larvae powder (HLP) and explore the underlying mechanism. A subcutaneous transplantation model (murine breast cancer cell 4T1-LUC) and lung metastasis model (murine melanoma cell B16-F10) were established to evaluate the anti-tumor and anti-metastasis effects of HLP. Honey bee larvae powder extract (HLE) was obtained by 70% ethanol extraction, and its chemical composition was determined according to physiochemical methods. Cell Counting Kit-8 assay was performed to test the cytotoxicity of HLE, and qRT-PCR assays were conducted to examine the mRNA levels of tumor marker EZH2 in HLE-treated tumor cells. In vivo xenograft tumor assays in BALB/c mice revealed dose-dependent suppression of tumor growth and lung metastasis showing an inhibition rate of 37.5% and 70.4% at 6 g/kg HLP-administered group with no toxicity to the animals. In vitro studies indicated that HLE showed no cytotoxicity to cancer cells at doses up to 1000 μg/mL, however, it significantly decreased EZH2 mRNA levels in HLE (1000 μg/mL)-treated B10-F10 cells (28.49%) and 4T1-LUC cells (26.75%). Further studies to elucidate the mechanisms involved and to isolate the active components of honey bee larva may provide more valuable information for its development and application in cancer treatment.

miR-101-3p induces autophagy in endometrial carcinoma cells by targeting EZH2

OBJECTIVE

This study aimed to investigate the effect of miR-101-3p on autophagy in endometrial carcinoma (EC) cells and the connection between miR-101-3p and EZH2.

METHODS

The expression levels of miRNAs were analyzed by microarray. The expression level of autophagy related proteins was measured by western blot. The mRNA expression level of beclin-1 was determined by qRT-PCR. Autophagy in EC cells was traced by GFP-LC3 fusion protein and observed by fluorescence microscopy. The number of autophagic vacuoles was determined by transmission electron microscopy (TEM). A luciferase reporter assay was utilized to assess the target relationship between miR-101-3p and EZH2.

RESULTS

The expression level of miR-101-3p in EC tissues was lower than in normal tissues. miR-101-3p upregulated the expression levels of the autophagy-related proteins LC3-II and beclin-1 in EC cells in a time- and dose-dependent manner. Overexpression of miR-101-3p and silencing of EZH2 both promoted autophagy in EC cells. Luciferase reporter assays verified that miR-101-3p inhibited EZH2 expression by binding to its 3'-UTR region.

CONCLUSION

miR-101-3p promoted autophagy in EC cells by downregulating the expression of EZH2, and it induced autophagy in EC cells by suppressing EZH2 expression. Inhibition of miR-101-3p could reduce its autophagy induction effect on EC cells.

Role of EZH2 in cancer stem cells: from biological insight to a therapeutic target

Epigenetic modifications in cancer stem cells largely result in phenotypic and functional heterogeneity in many solid tumors. Increasing evidence indicates that enhancer of zeste homolog 2 (EZH2), the catalytic subunit of Polycomb repressor complex 2, is highly expressed in cancer stem cells of numerous malignant tumors and has a critical function in cancer stem cell expansion and maintenance. Here, we review up-to-date information regarding EZH2 expression patterns, functions, and molecular mechanisms in cancer stem cells in various malignant tumors and discuss the therapeutic potential of targeting EZH2 in tumors.

Enhancer of zeste homolog 2 blockade by RNA interference is implicated with inhibited proliferation, invasion and promoted apoptosis in endometrial carcinoma

Endometrial carcinoma is the most common gynecological malignancy of the female genital tract worldwide (2012). Enhancer of zeste homolog 2 (EZH2), a critical component of the polycomb repressive complex 2, has been found to be associated with multiple biological processes and is overexpressed in multiple types of cancer. Previous studies have demonstrated that EZH2 is associated with endometrial carcinoma. The present study investigated the expression and biology function of EZH2 in endometrial cancer (EC). It was found that EZH2 levels were markedly increased in endometrial cancer tissues compared with that in adjacent normal tissues. EZH2 was significantly overexpressed in 3 separate endometrial cancer cell lines (Ishikawa, RL95-2 and HEC1-A) when compared with the normal endometrial cell line ESC. Additionally, small interfering RNA was used to investigate the role of EZH2 in endometrial carcinoma cell proliferation, and the results showed that EZH2 knockdown suppressed the proliferation of endometrial carcinoma cells in vitro. Furthermore, EZH2 knockdown induced apoptosis of human EC cells by promoting the expression of pro-apoptosis protein caspase 3, caspase 9, BCL2 associated X and decreasing the expression of anti-apoptosis protein Bcl-2. Finally, the present study demonstrated that EZH2 knockdown suppressed the invasion of EC cells through downregulation of the epithelial-mesenchymal transition. Collectively, these data demonstrate that EZH2 is frequently overexpressed in EC cells and its overexpression is associated with promoting the proliferation and invasion and decreasing the apoptosis of EC cells, suggesting that EZH2 may provide potential therapeutic targets for treatment of endometrial carcinoma.

Oncogenic histone methyltransferase EZH2: A novel prognostic marker with therapeutic potential in endometrial cancer

The histone methyltransferase EZH2, a key epigenetic modifier, is known to be associated with human tumorigenesis. However, the physiological importance of EZH2 and its clinical relevance in endometrial cancer remain unclear. Hence, in the present study, we investigated the expression and function of EZH2 in endometrial cancer. In a quantitative real-time PCR analysis of 11 endometrial cancer cell lines and 52 clinical endometrial cancer specimens, EZH2 was significantly overexpressed in cancer cells and tissues compared to that in corresponding normal control cells and tissues. Kaplan-Meier survival analysis using data of the TCGA RNA-seq database and tissue microarrays (TMAs) indicated that EZH2 overexpression is associated with endometrial cancer prognosis. In addition, knockdown of EZH2 using specific siRNAs resulted in growth suppression and apoptosis induction of endometrial cancer cells, accompanied by attenuation of H3K27 trimethylation. Consistent with these results, treatment with GSK126, a specific EZH2 inhibitor, suppressed endometrial cancer cell growth and decreased the number of cancer cell colonies. Furthermore, GSK126 showed additive effects with doxorubicin or cisplatin, which are conventional drugs for treatment of endometrial cancer. Further studies should explore the therapeutic potential of inhibiting EZH2 in patients with endometrial cancer.

Let-7c inhibits cholangiocarcinoma growth but promotes tumor cell invasion and growth at extrahepatic sites

Cholangiocarcinoma (CCA) is a cancer type with high postoperative relapse rates and poor long-term survival largely due to tumor invasion, distant metastasis, and multidrug resistance. Deregulated microRNAs (miRNAs) are implicated in several cancer types including CCA. The specific roles of the miRNA let-7c in cholangiocarcinoma are not known and need to be further elucidated. In our translational study we show that microRNA let-7c expression was significantly downregulated in human cholangiocarcinoma tissues when compared to adjacent tissues of the same patient. Let-7c inhibited the tumorigenic properties of cholangiocarcinoma cells including their self-renewal capacity and sphere formation in vitro and subcutaneous cancer cell growth in vivo. Ectopic let-7c overexpression suppressed migration and invasion capacities of cholangiocarcinoma cell lines in vitro, however, promoted distant invasiveness in vivo. Furthermore, we found that let-7c regulated the aforementioned malignant biological properties, at least in part, through regulation of EZH2 protein expression and through the DVL3/β-catenin axis. The miRNA let-7c thus plays an important dual role in regulating tumorigenic and metastatic abilities of human cholangiocarcinoma through mechanisms involving EZH2 protein and the DVL3/β-catenin axis.

KDM2B overexpression correlates with poor prognosis and regulates glioma cell growth

Background

Gliomas are one of the most lethal cancers in the human central nervous system. Despite clinical treatment advancements, the prognosis of patients with glioma remains poor. KDM2B is a histone lysine demethylase, which has been observed in multiple tumors. But the concrete role of KDM2B in gliomas remains to be further illustrated.

Methods

The KDM2B expression in gliomas was detected with immunohistochemistry and Western blot assay. Furthermore, knockdown of KDM2B in U87 and U251 glioma cell lines, the proliferation capacity was evaluated by cell viability assay, colon formation assay and flow cytometry in vitro. Western blot assay was used to analyze the p21, EZH2 and cyclinD1 changes followed by knockdown of KDM2B.

Results

KDM2B was upregulated in tissues of glioma patients, and the expression was correlated to cancer progression. Downregulation of KDM2B in U87 and U251 glioma cell lines inhibited cell proliferation and arrested cell cycle in G0/G1 phase. In addition, silencing KDM2B promoted the upregulation of p21 while reduced the expression of EZH2 and cyclinD1.

Conclusion

Taken together, our results revealed that KDM2B might influence gliomas growth and act as a novel therapeutic target for glioma patients.

EZH2 Impairs Human Dental Pulp Cell Mineralization via the Wnt/β-Catenin Pathway

The enhancer of zeste homolog 2 (EZH2) is a catalytic subunit of PRC2 (polycomb repressor complex 2). It mediates gene silencing via methyltransferase activity and is involved in the determination of cell lineage. However, the function of EZH2 and the underlying mechanisms by which it affects the differentiation of human dental pulp cell (hDPC) have remained underexplored. In this research, we found that EZH2 expression decreased during the mineralization of hDPCs, with attenuated H3K27me3 (trimethylation on lysine 27 in histone H3). Overexpression of EZH2 impaired the odontogenic differentiation of hDPCs, while EZH2 without methyltransferase activity mutation (mutation of suppressed variegation of 3 to 9, enhancer of zeste and trithorax domain, EZH2ΔSET) did not display this phenotype. In addition, siRNA knockdown studies showed that EZH2 negatively modulated hDPC differentiation in vitro and inhibited mineralized nodule formation in transplanted β-tricalcium phosphate / hDPC composites. To further investigate the underlying mechanisms, we explored the Wnt/β-catenin signaling pathway in view of the fact that previous research had documented the essential role that it plays during hDPC mineralization, as well as its links to EZH2 in other cells. We demonstrated for the first time that EZH2 depletion activated the Wnt/β-catenin signaling pathway and enhanced the accumulation of β-catenin in hDPCs. Chromatin immunoprecipitation analysis suggested that these effects are attributable to the level of the EZH2-regulated H3K27me3 on the β-catenin promoter. We conclude that EZH2 plays a negative role during the odontogenic differentiation of hDPCs. Suppression of EZH2 could promote hDPC mineralization by epigenetically regulating the expression of β-catenin and activating the Wnt canonical signaling pathway.

Expression of EZH2 in endometrial carcinoma and its effects on proliferation and invasion of endometrial carcinoma cells

Expression of enhancer of zeste homolog 2 (EZH2) has been implicated in cancer pathology, but research on its mechanistic activity is limited. The present study sought to assess the levels expression of EZH2 in patients with endometrial carcinoma (EC) and to explore the effects of EZH2 downregulation on the biological behavior of endometrial carcinoma RL-952 cells. Samples were obtained from a total of 104 patients with EC and an immunohistochemical assay was used to detect the expression of EZH2 in cancer and adjacent tissues. The relationship between the expression of EZH2 and the clinicopathological features was analyzed. Endometrial carcinoma RL-952 cells were transfected with chemically synthesized siRNA to conduct targeting inhibition of EZH2 expression. The expression levels of EZH2 protein were detected by immunoblotting. MTT and Transwell assays were used to detect the changes of cell proliferation and invasion after EZH2 downregulation. Of the 104 cases of endometrial carcinoma samples, 71 cases showed positive expression of EZH2, with an expression rate of 68.27%. In 104 cases of adjacent tissue samples, 25 cases showed positive expression of EZH2, with an expression rate of 24.03%. The expression of EZH2 in endometrial carcinoma tissue was significantly higher than that in adjacent tissue (P<0.05). The expression of EZH2 in endometrial carcinoma tissue was not correlated with the menopausal status and age of patients (P>0.05), but was correlated with the histological grade, depth of tumor invasion, lymph node metastasis and TNM stage (P<0.05). The expression of E2H2 was significantly downregulated by si-E2H2 and the proliferation and invasion abilities of cells were significantly reduced after EZH2 downregulation (P<0.05). EZH2 is closely related to the development of endometrial carcinoma and can enhance the proliferative activity of endometrial carcinoma RL-952 cells and promote cell invasion.

EZH2 inhibition in ARID1A mutated clear cell and endometrioid ovarian and endometrioid endometrial cancers

Clear cell carcinoma and endometrioid adenocarcinoma are histologic subtypes of ovarian and uterine cancer that demonstrate unique clinical behavior but share common underlying genomic aberrations and oncogenic pathways. ARID1A mutations are more frequently identified in these tumors, in comparison to other gynecologic histologies, and loss of ARID1A tumor suppressor function is thought to be an essential component of carcinogenic transformation. Several therapeutic targets in ARID1A mutated cancers are in development, including EZH2 inhibitors. EZH2 facilitates epigenetic methylation to modulate gene expression, and both uterine and ovarian cancers show evidence of EZH2 over expression. EZH2 inhibition in ARID1A mutated tumors acts in a synthetically lethal manner to suppress cell growth and promote apoptosis, revealing a unique new therapeutic opportunity. Several phase 1 and 2 clinical trials of EZH2 inhibitors are ongoing currently and there is considerable promise in translational trials for utilization of this new targeted therapy, both to capitalize on ARID1A loss of function and to increase sensitivity to platinum-based adjuvant chemotherapies. This review will synthesize the molecular carcinogenesis of these malignancies and their unique clinical behavior, as a foundation for an emerging frontier of targeted therapeutics - the synergistic inhibition of EZH2 in ARID1A mutated cancers.

Morphoproteomics, E6/E7 in-situ hybridization, and biomedical analytics define the etiopathogenesis of HPV-associated oropharyngeal carcinoma and provide targeted therapeutic options

BACKGROUND

Human papillomavirus (HPV) has been identified as an etiopathogenetic factor in oropharyngeal squamous cell carcinoma. The HPV E6 and E7 oncogenes are instrumental in promoting proliferation and blocking differentiation leading to tumorigenesis. Although surgical intervention can remove such tumors, the potential for an etiologic field effect with recurrent disease is real. A downstream effector of E7 oncoprotein, enhancer of zeste homolog 2 (EZH2), is known to promote proliferation and to pose a block in differentiation and in turn, could lead to HPV-induced malignant transformation. However, the EZH2 pathway is amenable to low toxicity therapies designed to promote differentiation to a more benign state and prevent recurrent disease by inhibiting the incorporation of HPV into the genome. This is the first study using clinical specimens to demonstrate EZH2 protein expression in oropharyngeal carcinoma (OPC).

METHODS

The study included eight patients with oropharyngeal carcinoma, confirmed p16INK4a- positive by immunohistochemistry (IHC). The tissue expression of E6/E7 messenger RNA (mRNA) was measured by RNAscope® in-situ hybridization technology. Expression of EZH2, Ki-67, and mitotic indices were assessed by morphoproteomic analysis. Biomedical analytics expanded the results with data from Ingenuity Pathway Analysis (IPA) and KEGG databases to construct a molecular network pathway for further insights.

RESULTS

Expression of E6 and E7 oncogenes in p16INK4a- positive oropharyngeal carcinoma was confirmed. EZH2 and its correlates, including elevated proliferation index (Ki-67) and mitotic progression were also present. Biomedical analytics validated the relationship between HPV- E6 and E7 and the expression of the EZH2 pathway.

CONCLUSION

There is morphoproteomic and mRNA evidence of the association of p16INK4a-HPV infection with the E6 and E7 oncogenes and the expression of EZH2, Ki-67 and mitotic progression in oropharyngeal carcinoma. The molecular network biology was confirmed by biomedical analytics as consistent with published literature. This is significant because the biology lends itself to targeted therapeutic options using metformin, curcumin, celecoxib and sulforaphane as therapeutic strategies to prevent progression or recurrence of disease.

Epigenetics in endometrial carcinogenesis - part 2: histone modifications, chromatin remodeling and noncoding RNAs

Carcinogenesis is a multistep multifactorial process that involves the accumulation of genetic and epigenetic alterations. In the past two decades, there has been an exponential growth of knowledge establishing the importance of epigenetic changes in cancer. Our work focused on reviewing the main role of epigenetics in the pathogenesis of endometrial carcinoma, highlighting the reported results concerning each epigenetic mechanistic layer. In a previous review, we assessed DNA methylation alterations. The present review examines the contribution of histone modifications, chromatin remodeling and noncoding RNA alterations for endometrial carcinogenesis.

LncRNA-ANCR down-regulation suppresses invasion and migration of colorectal cancer cells by regulating EZH2 expression

Our study aimed to explore the effects of long noncoding RNA (lncRNA)-ANCR on the invasion and migration of colorectal cancer (CRC) cells by regulating enhancer of zeste homolog 2 (EZH2) expression. CRC tissues and adjacent normal tissues were collected and CRC SW620 cells line and normal human intestinal epithelial cells (HIECs) were incubated. CRC SW620 cells line was transfected with ANCR-siRNA. The expressions of ANCR and EZH2 mRNA were measured by real-time quantitative polymerase chain reaction (RT-qPCR). EZH2 and trimethylation of H3K27 (H3K27me3) protein expressions were detected using Western blotting. The relationship between ANCR and EZH2 was determined through RNA pull-down and co-immunoprecipitation (co-IP) assays. Cell invasion and migration were determined by Trans-well and cell scratch assays. ANCR, EZH2 and H3K27me3 expressions were up-regulated in CRC tissues and SW620 cells (all P < 0.05). After transfected with ANCR-siRNA, SW620 cells showed decreased ANCR expression and EZH2 mRNA and protein expressions (all P < 0.05). According to the results of RNA pull-down and co-IP assays, ANCR could specifically bind to EZH2. The results of Trans-well and cell scratch tests showed that when ANCR expression was decreased, the invasion and migration abilities of SW620 cells significantly declined (both P < 0.05). In conclusion, these results suggest that lncRNA-ANCR could influence the invasion and migration of CRC cells by specifically binding to EZH2.

miR-98 inhibits hepatocellular carcinoma cell proliferation via targeting EZH2 and suppressing Wnt/β-catenin signaling pathway

Hepatocellular carcinoma (HCC) is a highly aggressive solid malignancy in the word. Aberrant microRNA (miRNA) expression is involved in human diseases including cancer. In the current study, we explore the function of miR-98 in HCC cell proliferation. We found that expression level of miR-98 was significantly decreased in HCC tissues and cells lines compared with adjacent non-tumor issues and human hepatic cell line LO2. Increased expression of miR-98 suppressed HCC cell proliferation and arrested HCC cell cycle in G0/G1 phase. While, suppressed expression of miR-98 showed the opposite effect. Bioinformatics analysis revealed EZH2, a putative tumor promoter as a potential target of miR-98. Additionally, luciferase reporter assay revealed that miR-98 directly binds to the 3'-untranslated region (3'-UTR) of EZH2 mRNA. Furthermore, we demonstrated that miR-98 could reduce the Wnt/β-catenin signal pathway by suppressing EZH2 directly. Moreover, inhibition of EZH2 abrogated the effect of miR-98 inhibitor on HCC cell proliferation. Taken together, these results suggested that miR-98 functioned as a potential tumor suppressor by regulating Wnt/β-catenin signal pathway through direct suppression of EZH2 expression and might sever as a potential therapeutic target for HCC patients.

MicroRNA-506 suppresses tumor proliferation and metastasis in colon cancer by directly targeting the oncogene EZH2

Increasing evidence reveals that aberrant expression of microRNA contributes to the development and progression of colon cancer, but the roles of microRNA-506 (miR-506) in colon cancer remain elusive. Here, we demonstrated that miR-506 was down-regulated in colon cancer tissue and cells and that miR-506 expression was inversely correlated with EZH2 expression, tumor size, lymph node invasion, TNM stage and metastasis. A high level of miR-506 identified patients with a favorable prognosis. In vitro and in vivo experiments confirmed that miR-506 inhibits the proliferation and metastasis of colon cancer, and a luciferase reporter assay confirmed that EZH2 is a direct and functional target of miR-506 via the 3′UTR of EZH2. The restoration of EZH2 expression partially reversed the proliferation and invasion of miR-506-overexpressing colon cancer cells. Moreover, we confirmed that the miR-506-EZH2 axis inhibits proliferation and metastasis by activating/suppressing specific downstream tumor-associated genes and the Wnt/β-catenin signaling pathway. Taking together, our study sheds light on the role of miR-506 as a suppressor for tumor growth and metastasis and raises the intriguing possibility that miR-506 may serve as a new potential marker for monitoring and treating colon cancer.

Role of the EZH2 histone methyltransferase as a therapeutic target in cancer

Besides being a genetic disease, cancer is also an epigenetic disease. The histone methyltransferase EZH2 is the catalytic subunit of PRC2, a highly conserved protein complex that regulates gene expression by methylating lysine 27 on histone H3. Given its role in tumorigenesis and its prognostic value in several tumor types, this protein appears a relevant therapeutic target. This review focuses on the preclinical and preliminary clinical results of studies investigating EZH2 inhibitors in human malignancies. These emerging data suggest that EZH2 inhibitors represent a very promising class of drugs, which will probably have a major impact on improving outcome and reducing toxicity for patients with indolent and aggressive B-cell lymphomas and other specific solid tumors.

Tumor progression, metastasis, and modulators of epithelial-mesenchymal transition in endometrioid endometrial carcinoma: an update

Endometrioid endometrial carcinoma (EEC), also known as type 1 endometrial cancer (EC), accounts for over 70-80% of all cases that are usually associated with estrogen stimulation and often develops in a background of atypical endometrial hyperplasia. The increased incidence of EC is mainly confined to this type of cancer. Most EEC patients present at an early stage and generally have a favorable prognosis; however, up to 30% of EEC present as high risk tumors, which have invaded deep into the myometrium at diagnosis and progressively lead to local or extra pelvic metastasis. The poor survival of advanced EC is related to the lack of effective therapies, which can be attributed to poor understanding of the molecular mechanisms underlying the progression of disease toward invasion and metastasis. Multiple lines of evidence illustrate that epithelial-mesenchymal transition (EMT)-like events are central to tumor progression and malignant transformation, endowing the incipient cancer cell with invasive and metastatic properties. The aim of this review is to summarize the current knowledge on molecular events associated with EMT in progression, invasion, and metastasis of EEC. Further, the role of epigenetic modifications and microRNA regulation, tumor microenvironment, and microcystic elongated and fragmented glands like invasion pattern have been discussed. We believe this article may perhaps stimulate further research in this field that may aid in identifying high risk patients within this clinically challenging patient group and also lead to the recognition of novel targets for the prevention of metastasis - the most fatal consequence of endometrial carcinogenesis.

Targeting EZH2 in cancer

Recent genomic studies have resulted in an emerging understanding of the role of chromatin regulators in the development of cancer. EZH2, a histone methyl transferase subunit of a Polycomb repressor complex, is recurrently mutated in several forms of cancer and is highly expressed in numerous others. Notably, both gain-of-function and loss-of-function mutations occur in cancers but are associated with distinct cancer types. Here we review the spectrum of EZH2-associated mutations, discuss the mechanisms underlying EZH2 function, and synthesize a unifying perspective that the promotion of cancer arises from disruption of the role of EZH2 as a master regulator of transcription. We further discuss EZH2 inhibitors that are now showing early signs of promise in clinical trials and also additional strategies to combat roles of EZH2 in cancer.

Aberrant overexpression of EZH2 and H3K27me3 serves as poor prognostic biomarker for esophageal squamous cell carcinoma patients

It has been reported that the trimethylation of histone 3 on lysine 27 (H3K27me3) is required for enhancer of zeste homology 2 (EZH2)-mediated repression of various genes essential for tumorigenesis and tumor development. Here, we reported the expression of EZH2 and H3K27me3 in esophageal squamous cell carcinoma (ESCC) specimens was higher than the pericarcinoma esophageal specimens. Their expression was positively associated with the poor prognosis of ESCC patients. EZH2 expression, histological grade and distant lymph node metastasis were all independent factors for poor prognosis of ESCC. In addition, enforced expression of EZH2 in esophageal cancer-derived cells could increase the overall H3K27me3 level. Our results suggested the expression of EZH2 and H3K27me3 could serve as biomarkers in the prediction of ESCC patients' survival and ESCC metastasis.

MicroRNA-101 targets EZH2, MCL-1 and FOS to suppress proliferation, invasion and stem cell-like phenotype of aggressive endometrial cancer cells

MicroRNA-101 has been implicated as a tumor suppressor miRNA in human tumors. However, its potential functional impact and the underlying mechanisms in endometrial cancer progression have not been determined. Here, we report that in aggressive endometrial cancer cells, re-expression of microRNA-101 leads to inhibition of cell proliferation and induction of apoptosis and senescence. Ectopic overexpression of microRNA-101 attenuates the epithelial-mesenchymal transition-associated cancer cell migration and invasion, abrogates the sphere-forming capacity and enhances chemosensitivity to paclitaxel. Algorithm and microarray-based strategies identifies potential microRNA-101 targets. Among these, we validated EZH2, MCL-1 and FOS as direct targets of miR-101 and silencing of these genes mimics the tumor suppressive effects observed on promoting microRNA-101 function. Importantly, further results suggest an inverse correlation between low miR-101 and high EZH2, MCL-1 and FOS expression in EC specimens. We conclude that, as a crucial tumor suppressor, microRNA-101 suppresses cell proliferation, invasiveness and self-renewal in aggressive endometrial cancer cells via modulating multiple critical oncogenes. The microRNA-101-EZH2/MCL-1/FOS axis is a potential therapeutic target for endometrial cancer.

Expression and clinicopathological significance of EED, SUZ12 and EZH2 mRNA in colorectal cancer

BACKGROUND AND OBJECTIVES

Enhancer of zeste 2 (EZH2), embryonic ectoderm development (EED), and suppressor of zeste 12 homolog (SUZ12), the key component of polycomb repressive complex 2, are of great importance in human cancer pathogenesis. This study was designed to investigate the clinical and prognostic significances of EZH2, EED and SUZ12 in colorectal cancer (CRC) patients.

METHODS

The expression of EZH2, EED and SUZ12 mRNA was evaluated in 82 primary CRC and paired non-cancerous mucosa samples by qRT-PCR.

RESULTS

We found that overall EZH2, EED and SUZ12 mRNA expression in the CRC tissues was significantly increased than in the non-cancerous tissue (p < 0.05). Increased EZH2, EED and SUZ12 mRNA expression was directly correlated with primary tumor size, regional lymph node metastases, distant metastasis and AJCC stage. Furthermore, CRC patients with higher level of EED, SUZ12 or EZH2 showed a worse disease-free survival (DFS) (p < 0.01). In multivariate analysis, the increased EZH2 expression may be a risk factor for the patients' 3-year DFS (HR 2.517; 95% CI 1.104, 5.736; p = 0.028). Furthermore, the k-means cluster analysis showed that high mRNA expression of EED, SUZ12 and EZH2 was significantly correlated with the aggressive clinical behavior and poor prognosis.

CONCLUSIONS

High expression of EED, SUZ12 and EZH2 might contribute to the CRC development/progression.

Reversible inhibition of lysine specific demethylase 1 is a novel anti-tumor strategy for poorly differentiated endometrial carcinoma

BACKGROUND

Endometrial cancer is the most common gynecologic malignancy. Type II endometrial carcinoma is often poorly differentiated and patients diagnosed with Type II disease (~11%) are disproportionately represented in annual endometrial cancer deaths (48%). Recent genomic studies highlight mutations in chromatin regulators as drivers in Type II endometrial carcinoma tumorigenesis, suggesting the use of epigenetic targeted therapies could provide clinical benefit to these patients. We investigated the anti-tumor efficacy of the LSD1 inhibitor HCI2509 in two poorly differentiated Type II endometrial cancer cell lines AN3CA and KLE.

METHODS

The effects of HCI2509 on viability, proliferation, anchorage-independent growth, global histone methylation, LSD1 target gene induction, cell cycle, caspase activation and TUNEL were assayed. KLE cells were used in an orthotopic xenograft model to assess the anti-tumor activity of HCI2509.

RESULTS

Both AN3CA and KLE cells were sensitive to HCI2509 treatment with IC50s near 500 nM for cell viability. Inhibition of LSD1 with HCI2509 caused decreased proliferation and anchorage independent growth in soft agar, elevated global histone methylation, and perturbed the cell cycle in both cell lines. These effects were largely dose-dependent. HCI2509 treatment also caused apoptotic cell death. Orthotopic implantation of KLE cells resulted in slow-growing and diffuse tumors throughout the abdomen. Tumor burden was distributed log-normally. Treatment with HCI2509 resulted 5/9 tumor regressions such that treatment and regressions were significantly associated (p=0.034).

CONCLUSIONS

Our findings demonstrate the anti-cancer properties of the LSD1 inhibitor HCI2509 on poorly differentiated endometrial carcinoma cell lines, AN3CA and KLE. HCI2509 showed single-agent efficacy in orthotopic xenograft studies. Continued studies are needed to preclinically validate LSD1 inhibition as a therapeutic strategy for endometrial carcinoma.

High protein expression of EZH2 is related to unfavorable outcome to tamoxifen in metastatic breast cancer

BACKGROUND

Metastatic breast cancer (MBC) is a highly heterogeneous disease with great differences in outcome to both chemo- and endocrine therapy. Better insight into the mechanisms underlying resistance is essential to better predict outcome to therapy and to obtain a more tailored treatment approach. We have previously described that increased mRNA expression levels of Enhancer of Zeste homolog (EZH2) are associated with worse outcome to tamoxifen therapy in MBC. Here, we explored whether this is also the case for EZH2 protein expression.

PATIENTS AND METHODS

A tissue microarray (TMA) was created using formalin-fixed, paraffin-embedded estrogen receptor (ER)-positive primary breast tumor tissues of 250 MBC patients treated with first-line tamoxifen. Quantity and intensity of EZH2 expression were determined by immunohistochemistry (IHC) and both were used to generate and group scores according to a previously described method for scoring EZH2.

RESULTS

In total, 116 tumors (46%) were considered to be EZH2 positive. The presence of EZH2 protein expression was significantly associated with progression-free survival (PFS) in both univariate [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.17-1.97, P = 0.002] and multivariate analysis including traditional factors associated with tamoxifen outcome (HR 1.41, 95% CI 1.06-1.88, P = 0.017). Considering quantity irrespective of intensity, tumors with >50% EZH2-positive cells had the worst PFS (HR 2.15, 95% CI 1.42-3.27, P < 0.001), whereas intensity alone did not show a significant association with PFS. Application of other methods of scoring EZH2 positivity resulted in a similar significant association between the amount of EZH2 positive cells and PFS.

CONCLUSION

In addition to EZH2 mRNA levels, these results suggest that protein expression of EZH2 can be used as a marker to predict outcome to tamoxifen therapy. This provides new rationale to explore EZH2 inhibition in the clinical setting and increases the possibilities for a more personalized treatment approach in MBC patients.

Enhancer of zeste homolog 2 is involved in the proliferation of endometrial carcinoma

Endometrial carcinoma is the second most common gynecological malignancy of the female genital tract worldwide. Enhancer of zeste homolog 2 (EZH2), a critical component of the polycomb repressive complex 2, has been found to be involved in multiple biological processes and is overexpressed in several types of cancer. Previous studies have demonstrated that EZH2 is associated with endometrial carcinoma. The present study showed that EZH2 was overexpressed in complex hyperplasia, atypical hyperplasia and endometrial cancer, but not in simple hyperplasia and normal endometrium. Additionally, by analyzing the correlation between EZH2 expression and clinicopathological characteristics, the expression of EZH2 was found to be associated with myometrial invasion and lymph-vascular space invasion of endometrial cancer. Furthermore, small interfering RNA was utilized to investigate the role of EZH2 in endometrial carcinoma cell proliferation, and the results showed that EZH2 knockdown suppressed the proliferation of endometrial carcinoma cells in vitro. Therefore, these findings indicate that EZH2 expression may predict a more aggressive biological behavior in endometrial carcinoma and it may provide potential therapeutic targets for treatment of endometrial carcinoma.

A long noncoding RNA Sox2ot regulates lung cancer cell proliferation and is a prognostic indicator of poor survival

Sox2 overlapping transcript (Sox2ot) is a long noncoding RNA (lncRNA), localized on human chromosome 3q26.33, which is frequently amplified in lung squamous cell carcinomas (SCCs). However, its roles in lung cancer remain under investigation. In this study, we found that Sox2ot was up-regulated over two folds in 53.01% of human primary lung cancers (44/83). The expression level of Sox2ot is significantly higher in SCCs than that in adenocarcinomas (ADCs) of the lung. Further study found high Sox2ot expression predicted poor survival in lung cancer patients (P=0.0053), implying Sox2ot is a novel prognostic factor. In two human lung cancer cell lines, HCC827 and SK-MES-1, knocking down Sox2ot inhibited cell proliferation by inducing G2/M arrest, with a concomitant decrease of cells in S phase. Reduced protein levels of Cyclin B1 and Cdc2 were also observed. Importantly, knocking down Sox2ot decreased EZH2 expression and reintroduction of EZH2 allowed Sox2ot knockdown cells progressed through G2/M phase, which correlates with the restoration of Cyclin B1 and Cdc2 expressions. Altogether, our data suggested that Sox2ot plays an important role in regulating lung cancer cell proliferation, and may represent a novel prognostic indicator for the disease.

3-Deazaneplanocin A (DZNep), an inhibitor of the histone methyltransferase EZH2, induces apoptosis and reduces cell migration in chondrosarcoma cells

OBJECTIVE

Growing evidences indicate that the histone methyltransferase EZH2 (enhancer of zeste homolog 2) may be an appropriate therapeutic target in some tumors. Indeed, a high expression of EZH2 is correlated with poor prognosis and metastasis in many cancers. In addition, 3-Deazaneplanocin A (DZNep), an S-adenosyl-L homocysteine hydrolase inhibitor which induces EZH2 protein depletion, leads to cell death in several cancers and tumors. The aim of this study was to determine whether an epigenetic therapy targeting EZH2 with DZNep may be also efficient to treat chondrosarcomas.

METHODS

EZH2 expression was determined by immunohistochemistry and western-blot. Chondrosarcoma cell line CH2879 was cultured in the presence of DZNep, and its growth and survival were evaluated by counting adherent cells periodically. Apoptosis was assayed by cell cycle analysis, Apo2.7 expression using flow cytometry, and by PARP cleavage using western-blot. Cell migration was assessed by wound healing assay.

RESULTS

Chondrosarcomas (at least with high grade) highly express EZH2, at contrary to enchondromas or chondrocytes. In vitro, DZNep inhibits EZH2 protein expression, and subsequently reduces the trimethylation of lysine 27 on histone H3 (H3K27me3). Interestingly, DZNep induces cell death of chondrosarcoma cell lines by apoptosis, while it slightly reduces growth of normal chondrocytes. In addition, DZNep reduces cell migration.

CONCLUSION

These results indicate that an epigenetic therapy that pharmacologically targets EZH2 via DZNep may constitute a novel approach to treat chondrosarcomas.

EZH2 regulates cancer cell migration through repressing TIMP-3 in non-small cell lung cancer

Histone methylations play important roles in human cancer metastasis. Enhancer of zeste homolog 2 (EZH2) is a key component of the polycomb repressor complex 2, which is responsible for histone H3K27 methylation. EZH2 is overexpressed in lung cancer and epigenetically silences tumor suppressor genes. Here, we showed that EZH2 was up-regulated in lung cancer and had a positive correlation with pathologic stage, nodal involvement in lung cancer patients. Moreover, overexpression of EZH2 was correlated with reduced tissue inhibitor of metalloproteinase-3 (TIMP-3) expression, which was shown to be negatively associated with tumor metastasis. Of note, overall survival time of patients with high EZH2/low TIMP-3 expression was significantly shorter than that of patients with low EZH2/high TIMP-3 (P = 0.031). RNA interfering and pharmacologic inhibition of EZH2 reduced histone H3 lysine 27 tri-methylation level and increased TIMP-3 expression level. Knockdown of EZH2 by siRNA significantly reduced A549 cancer cell migration. In contrast, reduction of TIMP-3 in A549 cells partially rescued EZH2 deficiency-induced loss of cell migration capacity. Taken together, our findings indicate that EZH2 accelerates cancer cell migration, in part, via the repression of TIMP-3 expression, suggesting a potential mechanism by which EZH2 promotes lung cancer progression and metastasis.