Morphological Changes Induced by TKS4 Deficiency Can Be Reversed by EZH2 Inhibition in Colorectal Carcinoma Cells

BACKGROUND

The scaffold protein tyrosine kinase substrate 4 (TKS4) undergoes tyrosine phosphorylation by the epidermal growth factor receptor (EGFR) pathway via Src kinase. The TKS4 deficiency in humans is responsible for the manifestation of a genetic disorder known as Frank-Ter Haar syndrome (FTHS). Based on our earlier investigation, the absence of TKS4 triggers migration, invasion, and epithelial-mesenchymal transition (EMT)-like phenomena while concurrently suppressing cell proliferation in HCT116 colorectal carcinoma cells. This indicates that TKS4 may play a unique role in the progression of cancer. In this study, we demonstrated that the enhancer of zeste homolog 2 (EZH2) and the histone methyltransferase of polycomb repressive complex 2 (PRC2) are involved in the migration, invasion, and EMT-like changes in TKS4-deficient cells (KO). EZH2 is responsible for the maintenance of the trimethylated lysine 27 on histone H3 (H3K27me3).

METHODS

We performed transcriptome sequencing, chromatin immunoprecipitation, protein and RNA quantitative studies, cell mobility, invasion, and proliferation studies combined with/without the EZH2 activity inhibitor 3-deazanoplanocine (DZNep).

RESULTS

We detected an elevation of global H3K27me3 levels in the TKS4 KO cells, which could be reduced with treatment with DZNep, an EZH2 inhibitor. Inhibition of EZH2 activity reversed the phenotypic effects of the knockout of TKS4, reducing the migration speed and wound healing capacity of the cells as well as decreasing the invasion capacity, while the decrease in cell proliferation became stronger. In addition, inhibition of EZH2 activity also reversed most epithelial and mesenchymal markers. We investigated the wider impact of TKS4 deletion on the gene expression profile of colorectal cancer cells using transcriptome sequencing of wild-type and TKS4 knockout cells, particularly before and after treatment with DZNep. Additionally, we observed changes in the expression of several protein-coding genes and long non-coding RNAs that showed a recovery in expression levels following EZH2 inhibition.

CONCLUSIONS

Our results indicate that the removal of TKS4 causes a notable disruption in the gene expression pattern, leading to the disruption of several signal transduction pathways. Inhibiting the activity of EZH2 can restore most of these transcriptomics and phenotypic effects in colorectal carcinoma cells.

Enhancer of zeste homolog 2 facilitates phenotypic transition of vascular smooth muscle cells leading to aortic aneurysm/dissection

Thoracic aortic aneurysms (TAAs) are a major cause of death owing to weaker blood vessel walls and higher rupture rates in affected individuals. Vascular smooth muscle cells (VSMCs) are the predominant cell type within the aortic wall and their dysregulation may contribute to TAA progression. Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, is involved in several pathological processes; however, the biological functions and mechanisms underlying VSMC phenotype transition and vascular intimal hyperplasia remain unclear. The present study aimed to determine the involvement of EZH2 in mediating VSMC function in the development of TAAs. The expression of EZH2 was revealed to be elevated in patients with thoracic aortic dissection and TAA mouse model through western blotting and reverse transcription-quantitative PCR experiments. Subsequently, a mouse model was established using β-aminopropionitrile. In vitro, EdU labeling, Transwell assay, wound healing assay and hematoxylin-eosin staining revealed that knocking down the Ezh2 gene could reduce the proliferation, invasion, migration, and calcification of mouse primary aortic smooth muscle cells. Flow cytometry analysis found that EZH2 deficiency increased cell apoptosis. Depletion of Ezh2 in mouse primary aortic VSMCs promoted the transformation of VSMCs from a synthetic to a contractile phenotype. Using RNA-sequencing analysis, it was demonstrated that Ezh2 regulated a group of genes, including integrin β3 (Itgb3), which are critically involved in the extracellular matrix signaling pathway. qChIP found Ezh2 occupies the Itgb3 promoter, thereby suppressing the expression of Itgb3. Ezh2 promotes the invasion and calcification of VSMCs, and this promoting effect is partially reversed by co-knocking down Itgb3. In conclusion, the present study identified a previously unrecognized EZH2-ITGB3 regulatory axis and thus provides novel mechanistic insights into the pathophysiological function of EZH2. EZH2 may thus serve as a potential target for the management of TAAs.

Participation of Long Noncoding RNA FOXP4-AS1 in the Development and Progression of Endometrioid Carcinoma with Epigenetically Silencing DUSP5

Background: Long noncoding RNAs (lncRNAs), as emerging regulators of a wide variety of biological processes via diverse mechanisms, have been demonstrated to be of increasing importance in biology. Genome-wide association studies of tumor samples have identified several lncRNAs as either oncogenes or tumor suppressors in various types of cancers. In recent years, the importance of lncRNAs, especially in endometrioid cancer (EEC), has become increasingly well understood. The lncRNA Forkhead box P4 antisense RNA 1 (FOXP4-AS1) has been reported to fulfill roles in several types of cancers; however, the main biological function and associated underlying molecular mechanism of FOXP4-AS1 in EEC have yet to be fully elucidated. Materials and Methods: The present study therefore aimed to investigate how RNA FOXP4-AS1 may participate in the development and progression of endometrioid carcinoma tissues. To meet this aim, in the present study, the expression level of FOXP4-AS1 was investigated in endometrioid carcinoma tissues and matching nearby normal endometrial tissues collected from patients receiving surgery at the hospital, and a series of molecular biological assays were performed to investigate the effect of FOXP4-AS1 on cell proliferation, cell migration, and cell invasion, and so on. Results: An increased concentration of FOXP4-AS1 was identified in endometrioid carcinoma samples and cell lines compared with the corresponding controls, and this lncRNA was found to be positively correlated with advanced FIGO stages in patients with endometrial cancer. Furthermore, knocking down endogenous FOXP4-AS1 led to a significant reduction in the colony formation number and a significant inhibition of cell proliferation, cell migration, and cell invasion in endometrioid carcinoma cells. Moreover, dual-specificity phosphatase 5 (DUSP5), which is lowly expressed in endometrioid carcinoma tissues cells and negatively modulated by FOXP4-AS1, was identified as the downstream target molecule of FOXP4-AS1. Subsequently, the mechanistic experiments confirmed that, through binding to enhancer of zeste homolog 2 (EZH2; one of the catalytic subunits of polycomb repressive complex 2 [PRC2]), FOXP4-AS1 could epigenetically suppress the expression of DUSP5. Finally, the oncogenic function of the FOXP4-AS1/EZH2/DUSP5 axis in endometrioid carcinoma was confirmed via rescue assays. Conclusions: The findings of the present study have highlighted how FOXP4-AS1 fulfills an oncogenic role in endometrioid carcinoma, and targeting FOXP4-AS1 and its pathway may provide new biomarkers for patients with endometrioid carcinoma.

Cyclohexene oxide CA, a derivative of zeylenone, exhibits anti-cancer activity in glioblastoma by inducing G0/G1 phase arrest through interference with EZH2

Introduction: Due to its highly aggressiveness and malignancy, glioblastoma (GBM) urgently requires a safe and effective treatment strategy. Zeylenone, a natural polyoxygenated cyclohexenes compound isolated from Uvaria grandiflora, has exhibited potential biological activities in various human diseases, including tumors. Methods: We designed and synthesized a series of (+)-Zeylenone analogues and evaluated their anti-GBM roles through structural-activity analysis. Cell Counting Kit-8, TUNEL, transwell and flow cytometry were employed for investigating the anticancer effects of CA on GBM cells. Western blotting, molecular docking, qRT-PCR and ChIP assays were performed to reveal the underlying mechanisms by which CA regulates the GBM cell cycle. The nude mouse xenograft model, HE staining, immunohistochemistry and was used to evaluate the anticancer effect of CA in vivo. Results: We identified CA ((1R, 2R, 3S)-3-p-fluorobenzoyl-zeylenone) as having the lowest IC50 value in GBM cells. CA treatment significantly inhibited the malignant behaviors of GBM cells and induced G0/G1 phase arrest in vitro. Furthermore, we validated the molecular mechanism by which CA interferes with EZH2, attenuating the down-regulation of cyclin-dependent kinase inhibitors p27 and p16 by the PRC2 complex. By establishing orthotopic nude mice models, we further validated the inhibitory role of CA on tumorigenesis of GBM cells in vivo and its potential values to synergistically potentiate the anti-tumor effects of EZH2 inhibitors. Conclusion: Overall, this paper elucidated the anti-GBM effects and potential mechanisms of CA, and may provide a therapeutic drug candidate for GBM treatment.

The Role of Hypoxia on the Trimethylation of H3K27 in Podocytes

Epigenetic alterations contribute to the pathogenesis of chronic diseases such as diabetes mellitus. Previous studies of our group showed that diabetic conditions reduce the trimethylation of H3K27 in podocytes in a NIPP1- (nuclear inhibitor of protein phosphatase 1) and EZH2- (enhancer of zeste homolog 2) dependent manner. It has been previously reported that in differentiated podocytes, hypoxia decreases the expression of slit diaphragm proteins and promotes foot process effacement, thereby contributing to the progression of renal disease. The exact mechanisms are, however, not completely understood. The aim of this study was to analyze the role of hypoxia and HIFs (hypoxia-inducible factor) on epigenetic changes in podocytes affecting NIPP1, EZH2 and H3K27me3, in vitro and in vivo. In vivo studies were performed with mice exposed to 10% systemic hypoxia for 3 days or injected with 3,4-DHB (dihydroxybenzoate), a PHD (prolyl hydroxylase) inhibitor, 24 h prior analyses. Immunodetection of H3K27me3, NIPP1 and EZH2 in glomerular podocytes revealed, to the best of our knowledge for the first time, that hypoxic conditions and pharmacological HIFs activation significantly reduce the expression of NIPP1 and EZH2 and diminish H3K27 trimethylation. These findings are also supported by in vitro studies using murine-differentiated podocytes.

EZH2 Contributes to Anoikis Resistance and Promotes Epithelial Ovarian Cancer Peritoneal Metastasis by Regulating m6A

OBJECTIVE

Histone modification has a significant effect on gene expression. Enhancer of zeste homolog 2 (EZH2) contributes to the epigenetic silencing of target chromatin through its roles as a histone-lysine N-methyltransferase enzyme. The development of anoikis resistance in tumor cells is considered to be a critical step in the metastatic process of primary malignant tumors. The purpose of this study was to investigate the effect and mechanism of anoikis resistance in ovarian adenocarcinoma peritoneal metastasis.

METHODS

In addition to examining EZH2 protein expression in ovarian cancer omental metastatic tissues, we established a model of ovarian cancer cell anoikis and a xenograft tumor model in nude mice. Anoikis resistance and ovarian cancer progression were tested after EZH2 and N6-methyladenosine (m6A) levels were modified.

RESULTS

EZH2 expression was significantly higher in ovarian cancer omental metastatic tissues than in normal ovarian tissues. Reducing the level of EZH2 decreased the level of m6A and ovarian cancer cell anoikis resistance in vitro and inhibited ovarian cancer progression in vivo. M6a regulation altered the effect of EZH2 on anoikis resistance.

CONCLUSION

Our results indicate that EZH2 contributes to anoikis resistance and promotes ovarian adenocarcinoma abdominal metastasis by m6A modification. Our findings imply the potential of the clinical application of m6A and EZH2 for patients with ovarian cancer.

CRISPR/Cas9‑mediated EZH2 knockout suppresses the proliferation and migration of triple‑negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive subtype of BC characterized by extensive intratumoral heterogeneity. Compared with other types of BC, TNBC is more prone to invasion and metastasis. The aim of the present study was to determine whether adenovirus-mediated clustered regulatory interspaced short palindromic repeats (CRISPR)/Cas9 system is capable of effectively targeting enhancer of zeste homolog 2 (EZH2) in TNBC cells and lay an experimental basis for the investigation of the CRISPR/Cas9 system as a gene therapy for BC. In the present study, EZH2 was knocked out in MDA-MB-231 cells using the CRISPR/Cas9 gene editing tool to create EZH2-knockout (KO) group (EZH2-KO group). Moreover, the GFP knockout group (control group), and a blank group (Blank group), were employed. The success of vector construction and EZH2-KO were verified by T7 endonuclease I (T7EI) restriction enzyme digestion, mRNA detection and western blotting. Changes in proliferation and migration ability of MDA-MB-231 cells following gene editing were detected by MTT, wound healing, Transwell and in vivo tumor biology assays. As indicated by the results of mRNA and protein detection, the mRNA and protein expression of EZH2 were significantly downregulated in the EZH2-KO group. The difference in EZH2 mRNA and protein between the EZH2-KO and the two control groups was statistically significant. MTT, wound healing and transwell assay suggested that the proliferation and migration ability of MDA-MB-231 cells in the EZH2-KO group were significantly decreased after EZH2 knockout. In vivo, the tumor growth rate in the EZH2-KO group was significantly lower than that in the control groups. In brief, the present study revealed that the biological functions of tumor cells were inhibited after EZH2 knockout in MDA-MB-231 cells. The aforementioned findings suggested that EZH2 can have a key role in the development of TNBC.

Targeting B7‑H3 through EZH2 inhibition in MYC‑positive Group 3 medulloblastoma

The most aggressive subtype of medulloblastoma (MB), Group 3, is characterized by MYC amplifications. However, targeting MYC has proven unsuccessful, and there remains a lack of therapeutic targets for treating MB. Studies have shown that the B7 homolog 3 (B7‑H3) promotes cell proliferation and tumor cell invasion in a variety of cancers. Similarly, it was recently revealed that B7‑H3 promotes angiogenesis in Group 3 MB and likely facilitates MB metastasis through exosome biogenesis. While therapies targeting B7‑H3 remain in the early stages of development, targeting upstream regulators of B7‑H3 expression may be more effective for halting MB progression. Notably, MYC and the enhancer of zeste homolog 2 (EZH2) are known to regulate B7‑H3 expression, and a previous study by the authors suggested that B7‑H3 amplifications present in MB are likely the result of EZH2‑MYC mediated activities. In the present study, it was reported that overexpression of EZH2 is associated with lower overall survival in Group 3 MB patients. It was also revealed that inhibition of EZH2 significantly reduces B7‑H3 and MYC transcript levels and upregulates miR‑29a, indicating that EZH2 post‑transcriptionally regulates B7‑H3 expression in Group 3 MB cells. Pharmacological inhibition of EZH2 using EPZ005687 attenuated MB cell viability and reduced the expression of B7‑H3. Similarly, pharmacological inhibition and knockdown of EZH2 led to the downregulation of MYC, B7‑H3, and H3K27me3. Further, EZH2 silencing induced apoptosis and reduced colony‑forming ability in MB cells, whereas EZH2 inhibition in MYC‑amplified C17.2 neural stem cells induced G2/M phase arrest while downregulating B7‑H3 expression. Collectively, the current study positions EZH2 as a viable target for the future development of MB treatments and that targeting EZH2 in combination with B7‑H3 immunotherapy may be an effective treatment for halting MB progression.

Epigenetic cues regulating airway development in human lung organoids: Polycomb repressive complex 2 and altered chromatin accessibility determine cell fate

Today, human organoids are becoming an integrated part of genomics and epigenomics, as they provide a platform that can be used for the definite study of molecular and cellular mechanisms occurring at different stages of development, particularly organogenesis, within the human body. Airway development is a complex process heavily influenced by epigenetic regulatory mechanisms in response to environmental changes, and as such, human lung organoids are an indispensable asset for further exploration of these mechanisms as a mode of transition from human in vitro to human ex vivo studies. Cultured primarily in compounds mimicking the extracellular matrix, such as Matrigel, these lung organoids have helped us to come to a better understanding of the role of polycomb repressive complex 2 (PRC2) and enhancer of zeste homolog 2 (EZH2) in lung epithelial cell differentiation and airway development, which was first reported in the FASEB journal in 2019. The following is an extended account of how the histone methylation-regulating PRC2 comes to play in the molding of the human bronchial tree, along with further epigenetic insights based on more recently developed human lung organoids.

EZH2: An Accomplice of Gastric Cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Understanding the factors influencing the therapeutic effects in gastric cancer patients and the molecular mechanism behind gastric cancer is still facing challenges. In addition to genetic alterations and environmental factors, it has been demonstrated that epigenetic mechanisms can also induce the occurrence and progression of gastric cancer. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressor complex 2 (PRC2), which trimethylates histone 3 at Lys-27 and regulates the expression of downstream target genes through epigenetic mechanisms. It has been found that EZH2 is overexpressed in the stomach, which promotes the progression of gastric cancer through multiple pathways. In addition, targeted inhibition of EZH2 expression can effectively delay the progression of gastric cancer and improve its resistance to chemotherapeutic agents. Given the many effects of EZH2 in gastric cancer, there are no studies to comprehensively describe this mechanism. Therefore, in this review, we first introduce EZH2 and clarify the mechanisms of abnormal expression of EZH2 in cancer. Secondly, we summarize the role of EZH2 in gastric cancer, which includes the association of the EZH2 gene with genetic susceptibility to GC, the correlation of the EZH2 gene with gastric carcinogenesis and invasive metastasis, the resistance to chemotherapeutic drugs of gastric cancer mediated by EZH2 and the high expression of EZH2 leading to poor prognosis of gastric cancer patients. Finally, we also clarify some of the current statuses of drug development regarding targeted inhibition of EZH2/PRC2 activity.

MLL1:EZH2 Ratio in Uterine Secretions and Endometrial Receptivity in Patients with Endometriosis

OBJECTIVE

To establish a novel approach for diagnosing endometriosis (EM) in patients with impaired endometrial receptivity.

METHOD

Mixed lineage leukemia 1 (MLL1) and enhancer of zeste homolog 2 (EZH2) levels were analyzed. The MLL1:EZH2 ratio in identifying impaired endometrial receptivity has been established and validated.

RESULTS

In normal endometrial tissue, the MLL1:EZH2 ratio increased significantly in the midsecretory phase, compared with that in the proliferative phase. In the midsecretory phase, the MLL1:EZH2 ratio in endometrial tissues and uterine secretions accurately identifies patients with EM who have impaired endometrial receptivity. In the validation group, the sensitivity and specificity of the MLL1:EZH2 ratio in the uterine secretions of the midsecretory phase, in diagnosing patients EM who have impaired endometrial receptivity, were 100% and 96.55%, respectively.

CONCLUSIONS

The MLL1:EZH2 ratio in uterine secretions of the midsecretory phase may serve as a marker to diagnose EM in patients with impaired endometrial receptivity.

LncRNA colorectal neoplasia differentially expressed promotes glycolysis of liver cancer cells by regulating hypoxia-inducible factor 1α

LncRNAs are associated with tumorigenesis of liver cancer. LncRNA Colorectal Neoplasia Differentially Expressed (CRNDE) was identified as an oncogenic lncRNA and involved in tumor growth and metastasis. The role of CRNDE in liver cancer was investigated. CRNDE was elevated in liver cancer cells. Knockdown of CRNDE decreased cell viability and inhibited proliferation of liver cancer. Moreover, knockdown of CRNDE reduced levels of extracellular acidification rate, glucose consumption, and lactate production to repress glycolysis of liver cancer. Silence of CRNDE enhanced the expression of miR-142 and reduced enhancer of zeste homolog 2 (EZH2) and hypoxia-inducible factor 1α (HIF-1α). Over-expression of HIF-1α attenuated CRNDE silence-induced decrease of glucose consumption and lactate production. Injection with sh-CRNDE virus reduced in vivo tumor growth of liver cancer through up-regulation of miR-142 and down-regulation of EZH2 and HIF-1α. In conclusion, knockdown of CRNDE suppressed cell proliferation, glycolysis, and tumor growth of liver cancer through EZH2/miR-142/HIF-1α.

Selective EZH2 inhibitor zld1039 alleviates inflammation in cisplatin-induced acute kidney injury partially by enhancing RKIP and suppressing NF-κB p65 pathway

Enhancer of zeste homolog 2 (EZH2), a component of polycomb repressive complex 2 (PRC2), is a histone lysine methyltransferase mediating trimethylation of histone H3 at lysine 27 (H3K27me3), which is a repressive marker at the transcriptional level. EZH2 sustains normal renal function and its overexpression has bad properties. Inhibition of EZH2 overexpression exerts protective effect against acute kidney injury (AKI). A small-molecule compound zld1039 has been developed as an efficient and selective EZH2 inhibitor. In this study, we evaluated the efficacy of zld1039 in the treatment of cisplatin-induced AKI in mice. Before injection of cisplatin (20 mg/kg, i.p.), mice were administered zld1039 (100, 200 mg/kg, i.g.) once, then in the following 3 days. We found that cisplatin-treated mice displayed serious AKI symptoms, evidenced by kidney dysfunction and kidney histological injury, accompanied by EZH2 upregulation in the nucleus of renal tubular epithelial cells. Administration of zld1039 dose-dependently alleviated renal dysfunction as well as the histological injury, inflammation and cell apoptosis in cisplatin-treated mice. We revealed that zld1039 administration exerted an anti-inflammatory effect in kidney of cisplatin-treated mice via H3K27me3 inhibition, raf kinase inhibitor protein (RKIP) upregulation and NF-κB p65 repression. In the cisplatin-treated mouse renal tubular epithelial (TCMK-1) cells, silencing of RKIP with siRNA did not abolish the anti-inflammatory effect of EZH2 inhibition, suggesting that RKIP was partially involved in the anti-inflammatory effect of zld1039. Collectively, EZH2 inhibition alleviates inflammation in cisplatin-induced mouse AKI via upregulating RKIP and blocking NF-κB p65 signaling in cisplatin-induced AKI. The potent and selective EZH2 inhibitor zld1039 has the potential as a promising agent for the treatment of AKI.

Circular RNA_ANKIB1 accelerates chemo-resistance of osteosarcoma via binding microRNA-26b-5p and modulating enhancer of zeste homolog 2

Osteosarcoma is a common bone malignancy in children and adolescents. Chemotherapeutic drug resistance is the major factor impacting the surgical outcome and prognosis of patients with osteosarcoma. This investigation assessed the role and mechanism of circular RNA_ANKIB1 in the development of osteosarcoma. The circular RNA (circ) _ANKIB1, microRNA (miR)-26b-5p, enhancer of zeste homolog 2 (EZH2) expression in OS samples was investigated through RT-qPCR. The EZH2, multidrug resistance protein 1 (MRP1), P-gp, and lipoprotein receptor-related protein (LRP) protein expressions were analyzed through western blot. The association between circ_ANKIB1 and the occurrence of clinic-pathological features in OS patients was assessed; the circular features of circ_ANKIB1 were analyzed. The hFOB1.19, KHOS, U2-OS OS cells were used to study the semi-inhibitory concentration IC50 of Doxorubicin (DXR)-resistant cells, clone formation, invasion, and apoptosis. The luciferase assay was used to study the binding of circ-ANKIB1 with miR-26b-5p and the targeting of miR-26b-5p with EZH2. In vivo experiments were performed via subcutaneous tumorigenic experiments. MiR-26b-5p in OS tissues and cells and DXR-resistant OS tissues and cells was silenced while circ_ANKIB1 and EZH2 were elevated. Circ_ANKIB1 silencing elevated miR-26b-5p, repressed EZH2, MRP1, P-gp, LRP, IC50, and elevated OS advancement. Circ_ANKIB1 bind miR-26b-5p. Reduced miR-26b-5p revered the influence of silencing circ_ANKIB1 on DXR resistant OS cells. MiR-26b-5p targeted EZH2, and EZH2 elevation reversed the impact of increasing miR-26b-5p on DXR resistant cells. Circ_ANKIB1 silencing suppressed DXR-resistant OS cells in vivo. In conclusion, Circ_ANKIB1 binds miR-26b-5p and modulates EZH2 to accelerate the chemo-resistance of osteosarcoma.

Histone methyltransferase enhancer of zeste 2 polycomb repressive complex 2 subunit exacerbates inflammation in depression rats by modulating microglia polarization

Depression is a major cause of emotional agony and degraded living quality. Enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) is involved in histone methylation in human diseases. This experiment was designed to investigate the mechanism of EZH2 on depression. Depression rat model was established via the treatment of chronic unpredictable mild stress (CUMS) to identify rat depression-like behaviors. EZH2 expression was determined and then silenced to assess its effect on depression-like behaviors and neuroinflammation. Microglia were isolated, cultured, identified and activated to assess EZH2 expression. Effect of EZH2 on microglia polarization was evaluated. Next, the binding relation between microRNA (miR)-29b-3p and EZH2 or matrix metallopeptidase 2 (MMP2) was analyzed. Levels of miR-29b-3p expression and MMP2 transcription were examined. Additionally, the role of miR-29b-3p in microglia polarization was tested. Depression-like behaviors were exhibited after CUMS induction. EZH2 was overexpressed in CUMS-treated rats and lipopolysaccharide (LPS)-induced microglia. EZH2 silencing reversed depression-like behaviors. EZH2 silencing mitigated inflammation in depression by manipulating microglia M2-type polarization. EZH2 targeted miR-29b-3p expression to promote MMP2 transcription. Inhibition of miR-29b-3p reversed the role of EZH2 silencing in microglia M2-type polarization and promoted inflammation. EZH2 inhibited miR-29b-3p expression by combining with miR-29b-3p promoter and trimethylation of histone H3-lysine 27-trimethylated upregulation, and then elevated MMP2 transcription and triggered microglia M1-type polarization, thus exacerbating depression-like behaviors and neuroinflammation of depression.

[Relationship between Expression of Runt-related Transcription Factor 3 and Enhancer of zeste Homolog 2 Proteins and Sensitivity to Neoadjuvant Chemotherapy in Locally Advanced Rectal Cancer]

Objective To investigate the expression and correlation of Runt-related transcription factor 3(RUNX3)and enhancer of zeste homolog 2(EZH2)in rectal cancer,and to reveal the relationship between the expression of RUNX3 and EZH2 and the sensitivity of XELOX regimen to neoadjuvant chemotherapy in locally advanced rectal cancer patients. Methods The carcinoma and paracancerous tissues of 31 patients with rectal adenocarcinoma and no preoperative antitumor therapy were selected as cancer group and paracancer group,respectively.The relative mRNA levels of RUNX3 and EZH2 in the two groups were measured by real-time quantitative reverse transcription-polymerase chain reaction,and the protein levels were determined by immunohistochemical assay.The expression of RUNX3 and EZH2 was compared between cancer tissue and paracancerous tissue.The pre-treatment wax blocks of 26 patients with locally advanced rectal cancer who received 3 cycles of XELOX regimen as neoadjuvant chemotherapy before surgery were selected as the pre-neoadjuvant therapy group,and the postoperative pathological wax blocks were selected as the post-neoadjuvant treatment group.Tumor regression grade(TRG)was determined to evaluate the efficacy of neoadjuvant therapy.Immunohistochemical assay was used to detect the protein levels of RUNX3 and EZH2 in the two groups,and then the relationship between the expression patterns of the two proteins and the efficacy of neoadjuvant chemotherapy was analyzed. Results Compared with paracancerous tissue,the cancer tissue showed down-regulated mRNA level and reduced positive protein expression rate of RUNX3,while up-regulated mRNA level(P=0.001)and increased positive protein expression rate of EZH2(P=0.022).The mRNA levels of RUNX3 and EZH2 in the cancer group were negatively correlated(r=-0.599,P=0.000).Twelve patients who received neoadjuvant chemotherapy reached TRG0-TRG2,and the overall effective rate of neoadjuvant chemotherapy was 46.15%(12/26).Compared with pre-neoadjuvant therapy group,the post-neoadjuvant therapy group had increased positive expression rate of RUNX3 protein(P=0.163)and decreased positive expression rate of EZH2 protein(P=0.095).In the pre-neoadjuvant therapy group,the effective rate of neoadjuvant chemotherapy was 75.00%(9/12)in patients with positive RUNX3 expression,77.78%(7/9)in patients with negative EZH2 expression,and 100%(7/7)in patients with positive expression of RUNX3 and negative expression of EZH2.Multivariate Logistic regression showed that the expression of RUNX3 protein was the factor influencing the efficacy of neoadjuvant chemotherapy. Conclusions The positive expression rate of RUNX3 in cancer tissue was lower than that in paracancerous tissue,while that of EZH2 showed the opposite trend.Neoadjuvant chemotherapy may affect the expression of RUNX3 and EZH2 in rectal cancer.The patients with high RUNX3 expression and low EZH2 expression in locally advanced rectal cancer were more sensitive to neoadjuvant chemotherapy with XELOX regimen.

The chromatin repressors EZH2 and Suv4-20h coregulate cell fate specification during hippocampal development

The cell fate transition from radial glial-like (RGL) cells to neurons and astrocytes is crucial for development and pathological conditions. Two chromatin repressors-the enhancer of zeste homolog 2 and suppressor of variegation 4-20 homolog-are expressed in RGL cells in the hippocampus, implicating these epigenetic regulators in hippocampal cell fate commitment. Using a double knockout mouse model, we demonstrated that loss of both chromatin repressors in the RGL population leads to deficits in hippocampal development. Single-nuclei RNA-Seq revealed differential gene expression and provided mechanistic insight into how the two chromatin repressors are critical for the maintenance of cycling cells in the dentate gyrus as well as the balance of cell trajectories between neuronal and astroglial lineages.

Zinc-finger protein 750 mitigates malignant biological behavior of oral CSC-like cells enriched from parental CAL-27 cells

Oral squamous cell carcinoma (OSCC) is the most commonly occurring oral malignancy. Cancer stem cells (CSCs) are known to be responsible for cancer recurrence and metastasis. Zinc-finger protein 750 (ZNF750) has been reported to inhibit OSCC cell proliferation and invasion. The present study aimed to elucidate the role of ZNF750 in the inhibition of the renewal ability of CSCs derived from the OSCC cell line, CAL-27. The effects of ZNF750 on CSC-like properties were examined using aldehyde dehydrogenase (ALDH), tumor sphere formation and colony formation assays. Reverse transcription-quantitative PCR and western blotting were performed to detect the expression levels of octamer-binding transcription factor 4, sex-determining region Y-box 2, the enhancer of zeste homolog 2 (Ezh2), embryonic ectoderm development (EED) and SUZ12 polycomb repressive complex 2 subunit (SUZ12), and for the identification of genes associated with metastasis. ZNF750 effectively attenuated CSC-like cell self-renewal abilities; ZNF750 decreased the ALDH-positive cell population, tumor sphere and colony formation abilities, cell viability and stemness factors. Furthermore, the expression levels of Ezh2, EED and SUZ12 were decreased by ZNF750. ZNF750 inhibited MMP1, 3, 9 and 13 expression levels, and decreased the cell invasion and migratory abilities. Moreover, the expression of tissue inhibitors of matrix metalloproteinases-1 was increased by ZNF750. However, opposite effects were observed following the knockdown of the ZNF750 gene. Overall, the present study demonstrated that ZNF750 has the potential to inhibit the renewal of CSC-like cells enriched from parental CAL-27 cells.

LncRNA SNHG1 promotes tumor progression and cisplatin resistance through epigenetically silencing miR-381 in breast cancer

The long-non-coding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) is a known cause of tumorigenesis. Nevertheless, it’s yet unclear how lncRNA SNHG1 influences breast cancer. Herein, we explored the mechanisms through which SNHG1 modulates breast cancer tumor progression. Our findings demonstrated that SNHG1 is significantly upregulated in breast cancer tissues and cells. High SNHG1 levels were closely linked to reduced survival rates in breast cancer patients. SNHG1 silencing has been shown to inhibit the proliferative, migratory, and invasive activity of breast cancer cells. Moreover, SNHG1 silencing enhanced cisplatin (DDP) sensitivity of these cells through improving DDP-induced cell apoptosis. Mechanistically, SNHG1 was found to interact with enhancer of zeste homolog 2 (EZH2), recruiting EZH2 to trigger trimethylation of histone H3 lysine 27 (H3K27me3), thus epigenetically inhibiting miR-381 transcription in these cells. Overexpression of miR-381 inhibited tumor progression and sensitized cells to the chemotherapeutic reagent DDP. More importantly, rescue experiments demonstrated that miR-381 inhibition could inverse the tumor-suppressive effect of SNHG1 silencing in breast cancer. In summary, SNHG1 silencing suppressed tumor progression and overcame breast cancer cell DDP resistance via the epigenetic suppression of miR-381 expression. Our study revealed that SNHG1 served as a novel therapeutic target for breast cancer chemoresistance.

Ilicicolin A Exerts Antitumor Effect in Castration-Resistant Prostate Cancer Via Suppressing EZH2 Signaling Pathway

The Polycomb protein enhancer of zeste homolog 2 (EZH2) has critical roles in prostate cancer (PCa) progression and drug-resistance, which remains an obstacle for PCa treatment. Enzalutamide (ENZ) is a second-generation androgen receptor antagonist employed for treatment of metastatic castration-resistant prostate cancer A considerable proportion of tumors eventually develop resistance during treatment. Thus, agents that can overcome resistance to PCa are needed urgently. Ilicicolin A (Ili-A), an ascochlorin derivative isolated from the coral-derived fungus Acremonium sclerotigenum GXIMD 02501, shows antiproliferative activity in human PCa cells, but its mechanism of action against Castration-resistant prostate cancer is not known. Herein, RNA-sequencing showed the EZH2 pathway to be involved in PCa proliferation. Ili-A at low doses reduced the protein level of EZH2, leading to transcriptional change. Interestingly, Ili-A suppressed the binding of EZH2 to promoter regions in AR/serine/threonine polo-like kinase-1/aurora kinase A. Moreover, Ili-A could enhance the anticancer activity of enzalutamide in CRPC cancer models. These data suggest that Ili-A could be used in combination with enzalutamide to treat CRPC.

Combination of curcumin with N-n-butyl haloperidol iodide inhibits hepatocellular carcinoma malignant proliferation by downregulating enhancer of zeste homolog 2 (EZH2) - lncRNA H19 to silence Wnt/β-catenin signaling

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common cause of cancer-related death worldwide. Curcumin (C) has been extensively investigated in different types of malignancies, including hepatocellular carcinoma, but its physicochemical properties have significantly influenced its clinical use. Several approaches are being explored to enhance curcumin's therapeutic response, including its combination with various drugs.

PURPOSE

This study aimed to evaluate the anti-tumor effect of curcumin (C) in combination with F2 (N-n-butyl haloperidol iodide) on hepatocellular carcinoma and its potential underlying mechanism in vitro and in vivo.

METHODS

Cell proliferation was evaluated by CCK-8 and colony formation assays, and apoptosis was measured by flow cytometry. The migratory and invasive abilities of Hep3B and SMMC-7721 cells were measured by wound-healing and matrigel transwell assays. In order to investigate the molecular pathways, various experiments such as western blotting, qPCR, RNA-seq, immunostaining and transfection were performed. To evaluate the anti-HCC effects in vivo, a xenograft tumor model was used.

RESULTS

Our findings showed that the combination of curcumin (C) & F2 (F2C) strongly inhibited malignant proliferation and migration in SMMC-7721 and Hep3B cells. The F2C treatment downregulates enhancer of zeste homolog 2 (EZH2) transcription and protein expression, which is key epigenetic regulator responsible for HCC development. Moreover, the inhibition of EZH2 by F2C led to Wnt/β-catenin signaling inhibition by decreasing tri-methylation of histone H3 at lysine 27 (H3K27me3) and long non-coding RNA H19 expression. The inhibition of F2C was associated with the suppression of tumorigenicity in xenograft HCC models.

CONCLUSION

These findings suggested that, F2C inhibited HCC formation, migration and its modulatory mechanism seemed to be associated with downregulation of EZH2, silencing Wnt/β-catenin signaling by interacting with H19, suggesting that F2C may be a promising drug in the clinical treatment of HCC.

Intermittent High Glucose Elevates Nuclear Localization of EZH2 to Cause H3K27me3-Dependent Repression of KLF2 Leading to Endothelial Inflammation

Epigenetic mechanisms have emerged as one of the key pathways promoting diabetes-associated complications. Herein, we explored the role of enhancer of zeste homolog 2 (EZH2) and its product histone 3 lysine 27 trimethylation (H3K27me3) in high glucose-mediated endothelial inflammation. To examine this, we treated cultured primary endothelial cells (EC) with different treatment conditions-namely, constant or intermittent or transient high glucose. Intermittent high glucose maximally induced endothelial inflammation by upregulating transcript and/or protein-level expression of ICAM1 and P-selectin and downregulating eNOS, KLF2, and KLF4 protein levels. We next investigated the underlining epigenetic mechanisms responsible for intermittent hyperglycemia-dependent endothelial inflammation. Compared with other high glucose treatment groups, intermittent high glucose-exposed EC exhibited an increased level of H3K27me3 caused by reduction in EZH2 threonine 367 phosphorylation and nuclear retention of EZH2. Intermittent high glucose also promoted polycomb repressive complex-2 (PRC2) assembly and EZH2's recruitment to histone H3. Abrupt enrichment of H3K27me3 on KLF2 and KLF4 gene promoters caused repression of these genes, further supporting endothelial inflammation. In contrast, reducing H3K27me3 through small molecule and/or siRNA-mediated inhibition of EZH2 rescued KLF2 level and inhibited endothelial inflammation in intermittent high glucose-challenged cultured EC and isolated rat aorta. These findings indicate that abrupt chromatin modifications cause high glucose-dependent inflammatory switch of EC.

TGF-β-MTA1-SMAD7-SMAD3-SOX4-EZH2 Signaling Axis Promotes Viability, Migration, Invasion and EMT of Hepatocellular Carcinoma Cells

Introduction

Enhancer of zeste homolog 2 (EZH2) is implicated in hepatocellular carcinoma (HCC), but whether transforming growth factor-β (TGF-β)-metastasis associated 1 (MTA1)-SMAD7-SMAD3-SRY-Box Transcription Factor 4 (SOX4)-EZH2 signaling axis, in which EZH2 participates, is also involved in HCC remained unknown.

Methods

Data on EZH2 expression in liver hepatocellular carcinoma (LIHC) and its relation with prognosis of HCC patients were predicted and analyzed using online databases. Following transfection with or without TGF-β1, HCC cell viability, migration and invasion were determined with MTT, Scratch and Transwell assays. Relative expressions of epithelial-to-mesenchymal transition (EMT)-related factors (N-Cadherin, Vimentin, and E-Cadherin) and TGF-β-MTA1-SMAD7-SMAD3-SOX4-EZH2 signaling axis factors (TGF-β, MTA1, SMAD7, phosphorylated-SMAD3, SOX4 and EZH2) were calculated via reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot.

Results

EZH2 was upregulated in HCC, which was related to poor prognosis. Silencing EZH2 suppressed EZH2 expression and HCC cell viability, migration, and invasion, and increased E-Cadherin expression yet decreased N-Cadherin and Vimentin expression, whereas EZH2 overexpression did conversely. Also, silencing EZH2 reversed the effects of TGF-β1 on promoting viability, migration, and invasion, as well as N-Cadherin and Vimentin expressions, yet suppressing E-Cadherin expression in HCC cells. In addition, TGF-β1 promoted TGF-β, MTA1, SOX4 and EZH2 expressions and p-SMAD3/SMAD3 ratio yet suppressed SMAD7, whereas silencing EZH2 solely reversed the effects of TGF-β1 on EZH2 expression in HCC cells.

Conclusion

The present study provides a theoretical basis for TGF-β-MTA1-SMAD7-SMAD3-SOX4-EZH2 signaling cascade in viability, migration, invasion, and EMT of HCC cells. Inhibiting these signals may represent a therapeutic pathway for the treatment of metastatic HCC.

Sevoflurane Inhibits Traumatic Brain Injury-Induced Neuron Apoptosis via EZH2-Downregulated KLF4/p38 Axis

Traumatic brain injury (TBI) is characterized by physical damage to the brain tissues, ensuing transitory or permanent neurological dysfunction featured with neuronal loss and subsequent brain damage. Sevoflurane, a widely used halogenated anesthetic in clinical settings, has been reported to alleviate neuron apoptosis in TBI. Nevertheless, the underlying mechanism behind this alleviation remains unknown, and thus was the focus of the current study. First, Feeney models were established to induce TBI in rats. Subsequently, evaluation of the modified neurological severity scores, measurement of brain water content, Nissl staining, and TUNEL assay were employed to investigate the neuroprotective effects of sevoflurane. Immunofluorescence and Western blot analysis were further applied to detect the expression patterns of apoptosis-related proteins as well as the activation of the p38-mitogen-activated protein kinase (MAPK) signaling pathway within the lesioned cortex. Additionally, a stretch injury model comprising cultured neurons was established, followed by neuron-specific enolase staining and Sholl analysis. Mechanistic analyses were performed using dual-luciferase reporter gene and chromatin immunoprecipitation assays. The results demonstrated sevoflurane treatment brought about a decrease blood-brain barrier (BBB) permeability, brain water content, brain injury and neuron apoptosis, to improve neurological function. The neuroprotective action of sevoflurane could be attenuated by inactivation of the p38-MAPK signaling pathway. Mechanistically, sevoflurane exerted an inhibitory effect on neuron apoptosis by up-regulating enhancer of zeste homolog 2 (EZH2), which targeted Krüppel-like factor 4 (KLF4) and inhibited KLF4 transcription. Collectively, our findings indicate that sevoflurane suppresses neuron apoptosis induced by TBI through activation of the p38-MAPK signaling pathway via the EZH2/KLF4 axis, providing a novel mechanistic explanation for neuroprotection of sevoflurane in TBI.

Phase II study of tazemetostat for relapsed or refractory B-cell non-Hodgkin lymphoma with EZH2 mutation in Japan

Tazemetostat is a selective, reversible, small-molecule inhibitor of the histone methyltransferase enzyme, enhancer of zest homolog 2 (EZH2). In this multicenter, open-label, phase II study, we assessed the efficacy and safety of tazemetostat in Japanese patients with relapsed or refractory (R/R) B-cell non-Hodgkin lymphoma harboring the EZH2 mutation. Tazemetostat (800 mg twice daily) was given orally (28-day cycle) until disease progression or unacceptable toxicity. Among the 20 eligible patients, 17 were enrolled in cohort 1 (follicular lymphoma [FL]), and three were enrolled in cohort 2 (diffuse large B-cell lymphoma). At data cut-off, the objective response rate in cohort 1 was 76.5%, including six patients (35.3%) with complete response and seven patients (41.2%) with partial response (PR). All three patients in cohort 2 achieved PR. In cohort 1, median progression-free survival (PFS) was not reached at the median follow-up of 12.9 months. The estimated PFS rate at 12 and 15 months was 94.1% and 73.2%, respectively. The most common grade 3 treatment-emergent adverse event (TEAE) was lymphopenia (n = 2). Grade 4 TEAEs included hypertriglyceridemia and pneumonia aspiration (n = 1 each), which were not related to tazemetostat. Treatment-emergent adverse events leading to study drug discontinuation were reported in four of the 20 patients, indicating that the safety profile of tazemetostat was acceptable and manageable. Tazemetostat 800 mg twice daily showed encouraging efficacy in patients with R/R EZH2 mutation-positive FL with a manageable safety profile in the overall population. Thus, tazemetostat could be a potential treatment for R/R EZH2 mutation-positive FL.

lncRNA HCP5 acts as a ceRNA to regulate EZH2 by sponging miR‑138‑5p in cutaneous squamous cell carcinoma

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are essential for the progression of tumors, including cutaneous squamous cell carcinoma (CSCC). The present study aimed to examine the competing endogenous RNA (ceRNA) network in CSCC. Differentially expressed genes in CSCC were analyzed using the GSE66359 microarray data set, and the upstream miRNAs and lncRNAs were predicted using online database analysis (TargetScan 7.1, mirDIP 4.1, miRSearch V3.0, miRDB and RNA22 2.0) and were verified in clinical tissues. RNA pull-down and dual luciferase reporter gene assays were used to verify the targeting relationships among lncRNA human histocompatibility leukocyte antigen complex P5 (HCP5), miR-138-5p and enhancer of zeste homolog 2 (EZH2). Cell lines with a high and low HCP5 expression were screened, and a pcDNA-3.1-HCP5 overexpression vector, small interfering RNA against HCP5, miR-138-5p mimics and miR-138-5p inhibitors were transfected into the CSCC cells. Cell viability, invasion, migration, apoptotic rate and autophagy were evaluated. The effects of HCP5 on autophagy and apoptosis of CSCC cells were verified in vivo using Ki67 and TUNEL staining. EZH2 was demonstrated to be upregulated in CSCC cells. miR-138-5p target sequences were identified in HCP5 and EZH2. HCP5 was revealed to function as a putative ceRNA of miR-138-5p to positively regulate EZH2, and EZH2 was shown to regulate autophagy and apoptosis of CSCC cells through the STAT3/VEGFR2 pathway. HCP5 overexpression decreased miR-138-5p levels, increased EZH2 levels and promoted cell malignant behaviors and autophagy but decreased the apoptosis rate. These trends were opposite when HCP5 was silenced. In conclusion, HCP5 may competitively bind to miR-138-5p to regulate EZH2 in CSCC cells, promoting autophagy and reducing apoptosis through the STAT3/VEGFR2 pathway. This study may provide a new perspective for understanding the molecular mechanism and treatment of CSCC.

lncRNA ILF3-AS1 promotes proliferation and metastasis of colorectal cancer cells by recruiting histone methylase EZH2

The role of long non-coding RNA (lncRNA) has been displayed in colorectal cancer (CRC). Here, we aimed to discuss the role of lncRNA interleukin enhancer-binding factor 3-antisense RNA 1 (ILF3-AS1)/enhancer of zeste homolog 2 (EZH2)/cyclin-dependent kinase inhibitor 2 (CDKN2A)/histone 3 (H3) lysine 27 trimethylation (H3K27me3) in cell proliferation and metastasis of CRC. ILF3-AS1, EZH2, and CDKN2A levels in CRC tissues and cells were detected. The relationship between ILF3-AS1/EZH2 expression and the clinicopathological features of CRC was analyzed. High/low expression of ILF3-AS1/EZH2 plasmids were composed to explore the function of ILF3-AS1/EZH2 in invasion, migration, proliferation, colony formation, and apoptosis of CRC cells. The growth status of nude mice was observed to verify the in vitro results from in vivo experiment. ILF3-AS1 and EZH2 increased, whereas CDKN2A reduced in CRC tissues and cells. ILF3-AS1 and EZH2 expression was linked to Dukes stage, distant metastasis, vascular invasion, and lymph node metastasis of CRC patients. Depleted ILF3-AS1 or reduced EZH2 suppressed proliferation, migration, colony-formation, and invasion ability, as well as facilitated apoptosis of CRC cells and attenuated the tumor growth in CRC mice. ILF3-AS1 accelerates the proliferation and metastasis of CRC cells by recruiting histone methylase EZH2 to induce trimethylation of H3K27 and downregulate CDKN2A.

Role of enhancer of zeste homolog 2 in osteoclast formation and periodontitis development by downregulating microRNA-101-regulated VCAM-1

The enhancer of zeste homolog 2 (EZH2) represents a potential target for periodontitis treatment; however, its role in the development of periodontitis remains unclear. The current study aimed to elucidate the role of EZH2 in osteoclasts (OCs) growth as well as the mechanism underpinning the related process. The potential interaction among EZH2, microRNA-101 (miR-101), and vascular cell adhesion molecule 1 (VCAM-1) was evaluated using chromatin immunoprecipitation and dual-luciferase reporter gene assay. The expressions of EZH2 and miR-101 in OCs were examined by Western blot analysis and reverse transcription squantitative polymerase chain reaction. Loss- and gain-function assays were then performed to determine the role of EZH2/miR-101/VCAM-1 in periodontitis and OCs proliferation, followed by OC growth and proliferation detected using tartrate resistant acid phosphatase (TRAP) and 5-ethynyl-2'-deoxyuridine staining. Enzyme-linked immunoassay was conducted to determine the expression of interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α). A periodontitis rat model was established to investigate the effect of EZH2 and VCAM-1 in vivo. EZH2 was overexpressed, while miR-101 was downregulated in the OCs of periodontitis. Silencing of EZH2, VCAM-1 repression, or miR-101 elevation suppressed the growth and proliferation of OC while acting to encumber the release of IL-1β and TNF-α. EZH2 negatively targeted miR-101, while miR-101 negatively targeted VCAM-1. Moreover, silencing of EZH2 or VCAM-1 was observed to attenuate periodontitis which was evidenced by an increase in BMD, BV/TV, and BS/BV as well as reduction in TRAP and cathepsin K in vivo. Taken together, the key findings of the current study demonstrate that EZH2 knockdown inhibited OC formation by elevating the expression of miR-101 via suppression of VCAM-1, ultimately attenuating periodontitis.

LINC02678 as a Novel Prognostic Marker Promotes Aggressive Non-small-cell Lung Cancer

Non-small-cell lung carcinoma (NSCLC) is considered to be a fatal disease and characterized by a poor prognosis. Long non-coding RNAs (lncRNAs) have been reported to act as biomarkers and therapeutic targets in solid tumors. However, the expression of lncRNAs and their clinical relevance in NSCLC remain undetermined. The gene expression data profiled in The Cancer Genome Atlas and Gene Expression Omnibus (GSE81089) were employed to screen differentially expressed lncRNAs in NSCLC. LINC02678 was found to be upregulated in NSCLC and exhibited hypomethylation of the promoter region in NSCLC tissues. LINC02678 (also called RP11-336A10.5) was associated with poorer overall survival and relapse-free survival in NSCLC patients. In vitro models of gain- and loss-of-function demonstrated that LINC02678 promotes NSCLC progression by promoting NSCLC cell proliferation and cell cycle progression, as well as inducing NSCLC cell migration, invasion and epithelial-mesenchymal transition. LINC02678 was primarily located in the nucleus and could bind with the enhancer of zeste homolog 2 (EZH2). Moreover, we found that LINC02678 knockdown impaired the occupancy capacity of EZH2 and trimethylation of lysine 27 on histone 3 (H3K27me3) at the promoter region of cyclin dependent kinase inhibitor 1B (CDKN1B) and E-cadherin, as confirmed by ChIP-qPCR. A mouse transplantation model further demonstrated that LINC02678 could promote the tumorigenic and metastatic capacities of NSCLC cells. We identified LINC02678 as a tumor promoter in NSCLC, which enhanced the growth and metastasis of NSCLC cells by binding with EZH2, indicating that LINC02678 may serve as a potential biomarker for cancer diagnosis and treatment.

EZH2-mediated inhibition of KLF14 expression promotes HSCs activation and liver fibrosis by downregulating PPARγ

OBJECTIVES

Induction of deactivation and apoptosis of hepatic stellate cells (HSCs) are principal therapeutic strategies for liver fibrosis. Krüppel-like factor 14 (KLF14) regulates various biological processes, however, roles, mechanisms and implications of KLF14 in liver fibrosis are unknown.

MATERIALS AND METHODS

KLF14 expression was detected in human, rat and mouse fibrotic models, and its effects on HSCs were assessed. Chromatin immunoprecipitation assays were utilized to investigate the binding of KLF14 to peroxisome proliferator-activated receptor γ (PPARγ) promoter, and the binding of enhancer of zeste homolog 2 (EZH2) to KLF14 promoter. In vivo, KLF14-overexpressing adenovirus was injected via tail vein to thioacetamide (TAA)-treated rats to investigate the role of KLF14 in liver fibrosis progression. EZH2 inhibitor EPZ-6438 was utilized to treat TAA-induced rat liver fibrosis.

RESULTS

KLF14 expression was remarkably decreased in human, rat and mouse fibrotic liver tissues. Overexpression of KLF14 increased LD accumulation, inhibited HSCs activation, proliferation, migration and induced G2/M arrest and apoptosis. Mechanistically, KLF14 transactivated PPARγ promoter activity. Inhibition of PPARγ blocked the suppressive role of KLF14 overexpression in HSCs. Downregulation of KLF14 in activated HSCs was mediated by EZH2-regulated histone H3 lysine 27 trimethylation. Adenovirus-mediated KLF14 overexpression ameliorated TAA-induced rat liver fibrosis in PPARγ-dependent manner. Furthermore, EPZ-6438 dramatically alleviated TAA-induced rat liver fibrosis. Importantly, KLF14 expression was decreased in human with liver fibrosis, which was significantly correlated with EZH2 upregulation and PPARγ downregulation.

CONCLUSIONS

KLF14 exerts a critical anti-fibrotic role in liver fibrosis, and targeting the EZH2/KLF14/PPARγ axis might be a novel therapeutic strategy for liver fibrosis.

Prognostic value of MTA1, SOX4 and EZH2 expression in esophageal squamous cell carcinoma

Esophageal cancer has always been one of the major malignant tumor types affecting the health of the Chinese population. Metastasis-associated protein 1 (MTA1), SOX4 and enhancer of zeste homolog 2 (EZH2) are all potent inducers of invasion and metastasis in esophageal squamous cell carcinoma (ESCC). However, the role of these signaling molecules and their implication in ESCC have remained largely elusive. In the present study, the effects of MTA1, SOX4 and EZH2 on the prognosis of patients with ESCC were explored. Immunohistochemistry was used to examine the expression levels of MTA1, SOX4 and EZH2. The χ² test was used to analyze the association between protein expression and clinicopathological parameters. Kaplan-Meier curves and Cox proportional hazards model survival analysis was performed to investigate the effects of the three proteins examined on disease prognosis. The results indicated that MTA1 may be used as a prognostic and diagnostic marker for ESCC. To the best of our knowledge, the present study was the first to demonstrate that MTA1-SOX4 signaling is associated with prognosis in ESCC. However, no significant association was noted between SOX4 and EZH2 in the present study, which was inconsistent with previously reported findings. The function of the MTA1-SOX4-EZH2 axis and the interactions of the proteins involved require further investigation.

EZH2 Inhibition Interferes With the Activation of Type I Interferon Signaling Pathway and Ameliorates Lupus Nephritis in NZB/NZW F1 Mice

Enhancer of zeste homolog 2 (EZH2) is a histone-lysine N-methyltransferase mediating trimethylation of H3K27, which represses gene expression and is critical to immune regulation. Inhibition of EZH2 is proved to have the potential of treating many diseases. However, whether inhibition of EZH2 affects type I interferon (IFN-I) signaling pathway, the abnormality of which is an important pathogenic mechanism for SLE, is still elusive. Here, we report, unexpectedly, a positive regulatory function of EZH2 in IFN-I signaling pathway, which contributes to the overactivation of IFN-I signaling pathway in SLE. We show that the expression of EZH2 was upregulated and positively correlated with the overexpression of interferon stimulated genes (ISGs) in both peripheral blood mononuclear cells and renal tissues of SLE patients. In vitro inhibition of EZH2 by either siRNAs or chemical inhibitors reduced the phosphorylation of STAT1 and the induction of ISGs stimulated by IFN-I. Additionally, inhibition of EZH2 interfered with the in vivo and ex vivo activation of IFN-I signaling pathway elicited by intravenous injection of adenovirus vector expressing mouse IFN-α5 and exogeneous stimulation with IFN-α, respectively. We evaluated the therapeutic effects of EZH2 inhibitor in NZB/NZW F1 mice which depend on IFN-I signaling pathway for the lupus-like disease development. Administration of EZH2 inhibitor prolonged the survival, reduced the levels of anti-dsDNA autoantibodies, and improved lupus nephritis of the mice. What’s more, EZH2 inhibitor attenuated the expression of ISGs in the kidneys of these mice. In summary, we show that excessive EZH2 contributes to the overactivation of IFN-I signaling pathway in SLE. EZH2 inhibitor has the potential to inhibit IFN-I signaling pathway and alleviate lupus nephritis. Additionally, diverse disease driving pathways exist among systemic lupus erythematosus (SLE) patient, and even in the same patients. Common regulators of different pathogenic pathways can be multivalent therapeutic targets. Together with previous studies showing EZH2 is involved in T-cell and B-cell mediated immune responses, EZH2 could be a potent multivalent therapeutic target for SLE.

LncRNA PART1 promotes cell proliferation and inhibits apoptosis of oral squamous cell carcinoma by blocking EZH2 degradation

Long noncoding RNAs (lncRNAs) have been considered as novel regulators in oral squamous cell carcinoma (OSCC). Enhancer of zeste homolog 2 (EZH2) can act as an oncogene in OSCC. This study intended to investigate whether lncRNA PART1 can exert its role in OSCC by regulating EZH2. The expression of PART1 in OSCC samples, tumors tissues, or OSCC cell lines was detected by qRT-PCR. The proliferation and apoptosis of OSCC cells were detected by CCK-8 and flow cytometry assays, respectively. The expression of PART1 and EZH2 were highly expressed in clinical OSCC tumors and cell lines. The expression level of PART1 was positively correlated to the size, clinical stage, and node metastasis of OSCC patients. Functionally, PART1 knockdown inhibited proliferation and facilitated apoptosis of OSCC cells. Mechanically, FUS interacted with PART1 and EZH2. Additionally, PART1 knockdown reduced the mRNA expression of EZH2, which was offset by FUS overexpression. The overexpression of FUS abrogated the effects of PART1 silence on proliferation and apoptosis of OSCC cells. The in vivo experiment revealed that PART1 knockdown inhibited tumor growth of OSCC cells in nude mice. This study indicated that PART1 exerts a carcinogenic role in OSCC by enhancing the stability of EZH2 protein.

LINC00511-dependent inhibition of IL-24 contributes to the oncogenic role of HNF4α in colorectal cancer

Hepatocyte nuclear factor 4 α (HNF4α) is an important transcription factor that acts as a pro-proliferative mediator during tumorigenesis, yet its function in colorectal cancer (CRC) remain unclear. Hence, this study aims to explore roles that HNF4α plays in the CRC development. RNA quantification analysis was conducted to characterize the expression pattern of long intergenic noncoding RNA 00511 (LINC00511)/HNF4α/IL-24 in CRC tissues and cell lines. Using gain- and loss-of-function approaches, effects of HNF4α/LINC00511/IL-24 axis on biological processes such as proliferative, migrating, invading, apoptotic, and tumorigenic functions of CRC cells were evaluated. We further identified the interactions among HNF4α/LINC00511/EZH2/IL-24 using RNA binding protein immunoprecipitation, RNA pull-down along with chromatin immunoprecipitation (ChIP). LINC00511 was an upregulated lncRNA in CRC tissues and cells, which played an oncogenic role by strengthening the malignant phenotypes of CRC cells. LINC00511 downregulated IL-24 expression by interacting with EZH2. HNF4α could enhance LINC00511 transcription in an epigenetic manner, which finally accelerated cancer progression and tumorigenesis through LINC00511-mediated inhibition of IL-24. Those data together demonstrated the contribution of HNF4α to the progression of CRC through mediating the LINC00511/EZH2/IL-24 axis. Hence, our study provides a promising therapeutic target for CRC.NEW & NOTEWORTHY Our findings on the roles of hepatocyte nuclear factor 4 α/long intergenic noncoding RNA 00511/IL-24 axis provide new insights into the CRC and offer potential targets for translational applications.

EZH2 inhibitor GSK343 inhibits sepsis-induced intestinal disorders

Enhancer of zeste homolog 2 (EZH2) is positively associated with poor clinical outcomes in a number of aggressive tumors. Recent studies have demonstrated that inhibition of EZH2 also suppressed the inflammatory response during sepsis. The present study aimed to investigate whether an inhibitor of EZH2, GSK343, could protect the intestine against sepsis-induced injury in vivo. Mice underwent cecal ligation and perforation (CLP) to induce sepsis and were assigned into three groups: Sham, CLP and CLP + GSK343. For GSK343 treatment, the septic mice were intravenously injected with GSK343 at 6 h post-CLP. The results indicated that EZH2 was highly expressed while tight junction (TJ) proteins ZO-1, occludin and claudin-1 expression was reduced in the intestinal tissue of mice subjected to CLP compared with the sham group. CLP operation also caused intestinal pathological injury and the production of inflammatory cytokines including TNF-α, IL-1β and IL-6 in both serum and intestinal tissues. Meanwhile, CLP induced cell apoptosis of intestinal tissue based on the increased number of apoptotic cells, reduced expression of Bcl-2 and higher expression of caspase-3 and Bax. However, the presence of GSK343 partially rescued intestinal pathological injury, reduced the level of inflammatory cytokines, repressed cell apoptosis and promoted TJ protein expression. Finally, the decreased number of Paneth cells caused by CLP operation was reversed by GSK343 treatment. In conclusion, the results of the present study demonstrated that GSK343 could protect the intestine against sepsis-induced injury in vivo. Inhibition of EZH2 may provide a therapeutic approach for intestinal dysfunction during sepsis.

Phase 1 study of tazemetostat in Japanese patients with relapsed or refractory B-cell lymphoma

Background

Tazemetostat is a selective and orally available inhibitor of enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and epigenetic regulator of cellular differentiation programs. We carried out a phase I study of tazemetostat in Japanese patients with relapsed or refractory B‐cell non‐Hodgkin‐type lymphoma (B‐NHL) to evaluate its tolerability, safety, pharmacokinetics, and preliminary antitumor activity.

Methods

Tazemetostat was given orally at a single dose of 800 mg on the first day and 800 mg twice daily (BID: total 1600 mg/d) on following days in a 28‐day/cycle manner. Tazemetostat dose‐limiting toxicity (DLT) was evaluated up to the end of the first treatment cycle. Archival tumor tissues were analyzed for hotspot EZH2 mutations.

Results

As of 15 January 2018, seven patients (four follicular lymphoma [FL] and three diffuse large B‐cell lymphoma [DLBCL]) were enrolled. The median age was 73 (range, 59‐85) years, and the median number of prior chemotherapy regimens was three (range, one to five). No DLT was observed (one patient was not evaluable due to early disease progression). The common treatment‐related adverse events (AEs) were thrombocytopenia and dysgeusia (three patients each; 42.9%). No treatment‐related serious AEs were observed. The objective response rate was 57% (4/7 patients), including responses in three of four patients with FL and one of three patients with DLBCL. An EZH2 mutation was detected in one patient with FL responding to treatment.

Conclusions

Tazemetostat at 800 mg BID showed an acceptable safety profile and promising antitumor activity in Japanese patients with relapsed or refractory B‐NHL.

Enhancer of zeste homolog 2 participates in the process of atherosclerosis by modulating microRNA-139-5p methylation and signal transducer and activator of transcription 1 expression

Atherosclerosis (AS) is the main cause of coronary heart disease, in which enhancer of zeste homolog 2 (EZH2) has been implied to participate in this process. Thus, this work proposed to explore the effect of EZH2 on AS from microRNA-139-5p (miR-139-5p)/signal transducer and activator of transcription 1 (STAT1) axis. EZH2, miR-139-5p, and STAT1 expression in arterial tissues of AS patients were detected. Human arterial smooth muscle cells (HASMCs) induced with oxidized low-density lipoprotein (ox-LDL) and the mice fed with high fat diet were treated with silenced EZH2 or upregulated miR-139-5p to explore their roles in proliferation and apoptosis of HASMCs, together with inflammation response and oxidative stress of mice. Chromatin immunoprecipitation experiment was applied to verify the regulatory effect of EZH2 on miR-139-5p through methylation of H3K27me3. The targeting relationship between miR-139-5p and STAT1 was verified by online website and luciferase activity assay. Reduced miR-139-5p and overexpressed EHZ2 and STAT1 were found in AS. Silenced EZH2 or elevated miR-139-5p decreased the production of cholesterol and inhibited inflammation reaction in serum of mice with AS. Silenced EZH2 or elevated miR-139-5p facilitated proliferation and restrained apoptosis of ox-LDL-treated HASMCs, and restrained oxidative stress and cell apoptosis in arterial tissues of AS mice. EZH2 regulated miR-139-5p through H3K27me3, and miR-139-5p targeted STAT1. miR-139-5p silencing antagonized the effects of EZH2 down-regulation on AS. This study manifests that down-regulated EZH2 or elevated miR-139-5p inhibits ox-LDL-induced HASMCs apoptosis, plaque formation, and inflammatory response in AS mice, which may be related to down-regulated STAT1.

Effect of EZH2 on pulmonary artery smooth muscle cell migration in pulmonary hypertension

Pulmonary hypertension (PH) is a life‑threatening disease that often involves vascular remodeling. Although pulmonary arterial smooth muscle cells (PASMCs) are the primary participants in vascular remodeling, their biological role is not entirely clear. The present study analyzed the role of enhancer of zeste homolog 2 (EZH2) in vascular remodeling of PH by investigating the behavior of PASMCs. The expression levels of EZH2 in PASMCs in chronic thromboembolic pulmonary hypertension (CTEPH), a type of PH, were detected. The role of EZH2 in PASMC migration was investigated by wound‑healing assay following overexpression and knockdown. Functional enrichment analysis of the whole‑genome expression profiles of PASMCs with EZH2 overexpression was performed using an mRNA Human Gene Expression Microarray. Quantitative (q)PCR was performed to confirm the results of the microarray. EZH2 expression levels increased in CTEPH cell models. The overexpression of EZH2 enhanced PASMC migration compared with control conditions. Functional enrichment analysis of the differentially expressed genes following EZH2 overexpression indicated a strong link between EZH2 and the immune inflammatory response and oxidoreductase activity in PASMCs. mRNA expression levels of superoxide dismutase 3 were verified by qPCR. The results suggested that EZH2 was involved in the migration of PASMCs in PH, and may serve as a potential target for the treatment of PH.

Downregulation of hsa_circ_0026123 suppresses ovarian cancer cell metastasis and proliferation through the miR‑124‑3p/EZH2 signaling pathway

Circular RNAs (circRNAs) play a role in various types of cancer. The present study suggested that hsa_ circ_0026123 expression was upregulated in ovarian cancer (OVA), which was associated with its role in OVA. However, the role of hsa_circ_0026123 in OVA cell invasion and proliferation remains unclear. In the present study, OVA tissues and cell lines were used to investigate the functions of hsa_circ_0026123. The associations between hsa_circ_0026123, miR-124-3p and enhancer of zeste homolog 2 (EZH2) were examined using a luciferase reporter assay. RT-qPCR and western blot analysis were used for gene and protein expression analysis, respectively. Tumor growth was detected using nude mouse tumor xenografts derived from SKOV3 cells, with or without hsa_circ_0026123 downregulation. The results confirmed that hsa_circ_0026123 expression was upregulated in OVA tissues and cell lines, while hsa_circ_0026123 silencing suppressed cell proliferation and migration; it also suppressed the expression of cancer stem cell (CSC) differentiation-related markers in either in vivoor in vitro experiments. The data revealed that hsa_circ_0026123 downregulation suppressed EZH2 expression by miR-124-3p 'sponging', which was confirmed by rescue experiments and luciferase reporter assays. The results revealed that hsa_circ_0026123 silencing suppressed ovarian cancer cell progression via the miR-124-3p/EZH2 signaling pathway. Overall, the findings demonstrated that hsa_circ_0026123 knockdown inhibited OVA cell progression by regulating the miR-124-3p/EZH2 axis. This methodology may thus be used for the targeted therapy of OVA, as well as a candidate biomarker for the diagnosis and treatment of OVA.

LncRNA MAGI2-AS3 Overexpression Sensitizes Esophageal Cancer Cells to Irradiation Through Down-Regulation of HOXB7 via EZH2

Background

Accumulating evidence has suggested that aberrant expression of long non-coding RNAs (lncRNAs) may contribute to cancer progression in association with radioresistance. The current study aimed to identify the potential role of lncRNA MAGI2-AS3 and the underlying mechanism in its regulation of the radio-sensitivity of esophageal cancer cells.

Methods and Results

Initially, we detected high expression of HOXB7 from microarray-based gene expression profiling of esophageal cancer. Then, we identified the interactions among MAGI2-AS3, HOXB7, and EZH2 by dual-luciferase reporter gene assay, RNA pull-down assay, RIP assay and ChIP assay. HOXB7 was highly-expressed, while MAGI2-AS3 was poorly-expressed in esophageal cancer tissues and cells. The effect of MAGI2-AS3 and HOXB7 on esophageal cancer cell proliferation and apoptosis as well as tumorigenicity of radioresistant cells was examined by gain- and loss-of-function experiments. Interestingly, MAGI2-AS3 down-regulated HOXB7 through interaction with EZH2, which promoted cell apoptosis and inhibited proliferation and radio-resistance. Besides, down-regulation of MAGI2-AS3 exerted a promoting effect on these malignant phenotypes.

Conclusion

Taken together, our results reveal the potential role of MAGI2-AS3 over-expression in controlling esophageal cancer resistance to radiotherapy by down-regulating HOXB7, this providing a candidate biomarker for resistance to radiotherapy.

LINC00565 promotes the progression of colorectal cancer by upregulating EZH2

The present study aimed to illustrate the role of LINC00565 in aggravating colorectal cancer (CRC) by targeting enhancer of zeste homolog 2 (EZH2). The relative levels of LINC00565 and EZH2 in CRC tissues, based on their Tumor-Node-Metastasis stage and tumor size, were detected by reverse transcription-quantitative polymerase chain reaction. The diagnostic value of LINC00565 in CRC was assessed by depicting receiver operating characteristic curves. Pearson's correlation test was applied to analyze the expression correlation between LINC00565 and EZH2 in CRC tissues. The transfection efficacy of three LINC00565 small interfering RNAs was examined in CRC HCT116 and SW480 cell lines. After knockdown of LINC00565, the proliferative and migratory abilities of CRC cells were detected by Cell Counting Kit-8 and Transwell assays, respectively. The subcellular distribution of LINC00565 was analyzed, and the interaction between LINC00565 and EZH2 was determined by RNA immunoprecipitation. Finally, co-regulation of LINC00565 and EZH2 on CRC cell functions was explored by performing rescue experiments. Results showed that LINC00565 was upregulated in CRC tissues, especially in patients with stage III+IV and in those with large tumor sizes, suggesting its diagnostic value in CRC. EZH2 was also upregulated in CRC tissues, showing a positive correlation with LINC00565. LINC00565 was mainly expressed in the cytoplasm and was found to bind with EZH2. Validation was performed by overexpressing EZH2, which abolished the role of silenced LINC00565 in regulating proliferative and migratory abilities in CRC. Therefore, the upregulation of LINC00565 in CRC tissues was found to stimulate the aggravation of CRC by upregulating EZH2.

MBD2 and EZH2 regulate the expression of SFRP1 without affecting its methylation status in a colorectal cancer cell line

Secreted frizzled-related protein 1 (SFRP1), which is an extracellular inhibitor involved in Wnt signalling, is downregulated by promoter hypermethylation in the early stages of colorectal tumorigenesis. Polycomb (PCG) and methyl-CpG-binding domain (MBD) proteins that serve a role in epigenetic gene regulation. The aim of the present study was to determine the role of PCG and MBD proteins in the regulation of SFRP1 gene expression in colorectal cancer (CRC), specifically in CRC cell lines and the human embryo intestinal mucosa cell line CCC-HIE-2. The methylation status of the SFRP1 gene promoter were analysed using methylation-specific PCR (MSP), whereas SFRP1 mRNA expression was analysed using reverse transcription-quantitative PCR. The association between PCG and MBD proteins and the SFRP1 gene was assessed, where associated proteins were screened by chromatin immunoprecipitation and their expression were subsequently knocked down using RNA interference to determine their role in the regulation of SFRP1 gene expression. The SFRP1 promoter was demonstrated to be hypermethylated in CRC cell lines and partially methylated in the non-cancerous cell line CCC-HIE-2. SFRP1 mRNA expression was significantly lower in CRC cell lines compared with that of CCC-HIE-2 cells. The expression of PCGs enhancer of zeste homolog 2 (EZH2) and BMI1, along with MBD2, was indicated to be upregulated with SFRP1 methylation in HCT116 and SW480 cells. The SFRP1 promoter region was enriched with EZH2 in CCC-HIE-2 cells and enriched with EZH2 and MBD2 in SW480 cells, whereas none of the proteins examined were indicated on the SFRP1 promoter in HCT116 cells. The expression of SFRP1 was reactivated by MBD2 small interfering (si)RNA but not by EZH2 siRNA in SW480 cells, but combined MBD2 and EZH2 knockdown effectively restored SFRP1 gene expression without affecting the methylation status of the SFRP1 promoter. In conclusion, data from the present study revealed that MBD2 and EZH2 regulated SFRP1 expression without affecting the hypermethylation of SFRP1 in CRC cell lines. Instead, the regulation of SFRP1 expression may be through a distinct mechanism, which warrants further investigation.

Polycomb repressor complex 2 function in breast cancer (Review)

Epigenetic modifications are important contributors to the regulation of genes within the chromatin. The polycomb repressive complex 2 (PRC2) is a multi‑subunit protein complex that is involved in silencing gene expression through the trimethylation of lysine 27 at histone 3 (H3K27me3). The dysregulation of this modification has been associated with tumorigenicity through the increased repression of tumour suppressor genes via condensing DNA to reduce access to the transcription start site (TSS) within tumor suppressor gene promoters. In the present review, the core proteins of PRC2, as well as key accessory proteins, will be described. In addition, mechanisms controlling the recruitment of the PRC2 complex to H3K27 will be outlined. Finally, literature identifying the role of PRC2 in breast cancer proliferation, apoptosis and migration, including the potential roles of long non‑coding RNAs and the miR‑200 family will be summarized as will the potential use of the PRC2 complex as a therapeutic target.

EZH2 as a Regulator of CD8+ T Cell Fate and Function

Enhancer of zeste 2 (EZH2) is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) that mediates di- and trimethylation of histone 3 lysine 27 effectively precluding successful gene transcription at these loci. This class of epigenetic modifications facilitates the maintenance of tissue-specific cellular transcriptional programs as cells undergoing successive rounds of proliferation. CD8+ T cells are effective mediators of adaptive immunity and function to eliminate virus- and bacteria-infected cells as well as tumor cells. Upon recognition of cognate antigen, T cells undergo activation/proliferation to clear the target cells. The heterogeneous population of responding T cells formed during these proliferative events thus rely on epigenetic modifications to ensure identity and confer functional capabilities. In this review, we will focus on the role of the dynamic expression EZH2 in shaping the epigenetic landscape of CD8+ T cell fate and function, with a particular emphasis on infection and cancer. We also explore competing hypotheses pertaining to EZH2 function and the prospects of clinical EZH2 inhibitors in fine-tuning T cell responses.

Inhibition of EZH2 (Enhancer of Zeste Homolog 2) Attenuates Neuroinflammation via H3k27me3/SOCS3/TRAF6/NF-κB (Trimethylation of Histone 3 Lysine 27/Suppressor of Cytokine Signaling 3/Tumor Necrosis Factor Receptor Family 6/Nuclear Factor-κB) in a Rat Model of Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Neuroinflammation has been proven to play an important role in the pathogenesis of early brain injury after subarachnoid hemorrhage (SAH). EZH2 (enhancer of zeste homolog 2)-mediated H3K27Me3 (trimethylation of histone 3 lysine 27) has been recognized to play a critical role in multiple inflammatory diseases. However, there is still a lack of evidence to address the effect of EZH2 on the immune response of SAH. Therefore, the aim of this study was to determine the role of EZH2 in SAH-induced neuroinflammation and explore the effect of EZH2 inhibition with its specific inhibitor EPZ6438.

METHODS

The endovascular perforation method was performed on rats to induce subarachnoid hemorrhage. EPZ6438, a specific EZH2 inhibitor, was administered intraperitoneally at 1 hour after SAH. SOCS3 (Suppressor of cytokine signaling 3) siRNA and H3K27me3 CRISPR were administered intracerebroventricularly at 48 hours before SAH to explore potential mechanisms. The SAH grade, short-term and long-term neurobehavioral tests, immunofluorescence staining, and western blots were performed after SAH.

RESULTS

The expression of EZH2 and H3K27me3 peaked at 24 hours after SAH. In addition, inhibition of EZH2 with EPZ6438 significantly improved neurological deficits both in short-term and long-term outcome studies. Moreover, EPZ6438 treatment significantly decreased the levels of EZH2, H3K27Me3, pathway-related proteins TRAF6 (TNF [tumor necrosis factor] receptor family 6), NF-κB (nuclear factor-κB) p65, proinflammatory cytokines TNF-α, IL (interleukin)-6, IL-1β, but increased the expression levels of SOCS3 and anti-inflammatory cytokine IL-10. Furthermore, administration of SOCS3 siRNA and H3k27me3-activating CRISPR partly abolished the neuroprotective effect of EPZ6438, which indicated that the neuroprotective effect of EPZ6438 acted, at least partly, through activation of SOCS3.

CONCLUSIONS

In summary, the inhibition of EZH2 by EPZ6438 attenuated neuroinflammation via H3K27me3/SOCS3/TRAF6/NF-κB signaling pathway after SAH in rats. By targeting EZH2, this study may provide an innovative method to ameliorate early brain injury after SAH.

STAT3-Induced Upregulation of lncRNA CASC9 Promotes the Progression of Bladder Cancer by Interacting with EZH2 and Affecting the Expression of PTEN

Objective

Long non-coding RNA (lncRNA) cancer susceptibility candidate 9 (CASC9) has been reported to play a vital role in tumorigenesis. This study explored the biological role of CASC9 and its regulation mechanism in bladder cancer (BC).

Methods

Gene expression was evaluated using quantitative reverse transcription polymerase chain reaction and Western blot. The functional role of CASC9 in BC was studied using Cell Counting Kit-8, colony formation assay, scratch wound healing assay, transwell invasion assay, and xenograft tumor assay. In addition, the mechanism of CASC9 function in BC was determined using RNA immunoprecipitation assay and chromatin immunoprecipitation assay.

Results

CASC9 was upregulated in BC tissues and cell lines, and correlated with the staging and metastasis in BC. Knockdown of CASC9 inhibited the proliferation, migration, and invasion of BC cells. Similarly, silencing of CASC9 inhibited tumor growth in vivo. Signal transducer and activator of transcription 3 (STAT3) was upregulated in BC tissues and cell lines, and positively correlated with CASC9 in BC tissues. Moreover, CASC9 was shown to be regulated by STAT3 in BC cells. Furthermore, CASC9 regulated phosphatase and tensin homolog (PTEN) expression by interacting with enhancer of zeste homolog 2 (EZH2). More significantly, CASC9 silencing-mediated inhibition of BC progression was partly reversed by EZH2 overexpression or PTEN inhibition.

Conclusion

Upregulation of CASC9 induced by STAT3 promoted the progression of BC by interacting with EZH2 and affecting the expression of PTEN, representing a novel regulatory mechanism for BC progression.

Effect of enhancer of zeste homolog 2 mutations on the prognosis of patients with myelodysplastic syndrome: A meta-analysis

BACKGROUND

Gene mutations with important prognostic roles have been identified in patients with myelodysplastic syndrome (MDS). Overall, it is not yet fully clear whether enhancer of zeste homolog 2 (EZH2) is affected and contributes to the disease in MDS patients. Thus, we performed a meta-analysis to investigate the effects of EZH2 mutations on the prognosis of patients with MDS.

METHODS

We searched English-language databases (PubMed, Embase, and Cochrane Library) for studies published on the effects of EZH2 mutations in MDS patients. The study had to include at least 1 of the following indices as therapeutic evaluation data: overall survival (OS), transformation time to leukemia, and International Prognostic Scoring System risk. Revman, version 5.2 software was used for all statistical processing. We calculated the risk ratio and the 95% confidence interval (CI) of continuous variables, and determined the hazard ratio and 95% CI of time-to-event data.

RESULTS

We included 5 studies with a total enrolment of 994 patients. There was a significant adverse effect on OS in the EZH2-mutation group compared to the unmutated group (hazard ratio = 2.47, 95% CI: 1.37-4.47, P < .00001), while the heterogeneity was relatively high (I = 68%). There was no significant correlation between EZH2 mutations and IPSS risk (low/int-1 vs int-2/high) (odds ratio: 0.69, 95% CI: 0.14-3.39, P = .65), with significant heterogeneity (I = 78%). The analysis did not show significant publication bias in the studies.

CONCLUSION

This meta-analysis indicated an adverse effect of EZH2 mutations with regard to OS in patients with MDS. However, larger cohort trials are still needed to better understand the prognostic impacts of EZH2 mutations on MDS patients.

Determination of long non-coding RNAs associated with EZH2 in neuroblastoma by RIP-seq, RNA-seq and ChIP-seq

Neuroblastoma (NB) is the most common type of extracranial solid tumor found in children. Despite several treatment options, patients with advanced stage disease have a poor prognosis. Previous studies have reported that enhancer of zeste homolog 2 (EZH2) and long non-coding RNAs (lncRNAs) have abnormal expression levels in NB and participate in tumorigenesis and NB development. However, the association between EZH2 and lncRNAs remain unclear. In the present study, RNA immunoprecipitation-sequencing (RIP-seq) was used to analyze the lncRNAs binding to EZH2. Following EZH2 knockdown via short hairpin RNA, RNA-seq was performed in shEZH2 and control groups in SH-SY5Y cells. Chromatin IP (ChIP)-seq was used to determine the genes that may be regulated by EZH2. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to identify the signaling pathways involved in NB. The results from RIP-seq identified 94 lncRNAs, including SNHG7, SNHG22, KTN-AS1 and Linc00843. Furthermore, results from RNA-seq demonstrated that, following EZH2 knockdown, 448 genes were up- and 571 genes were downregulated, with 32 lncRNAs up- and 35 downregulated and differentially expressed compared with control groups. Certain lncRNAs, including MALAT1, H19, Linc01021 and SNHG5, were differentially expressed in EZH2-knockdown group compared with the control group. ChIP-seq identified EZH2 located in the promoter region of 138 lncRNAs including CASC16, CASC15, LINC00694 and TBX5-AS1. In summary, the present study demonstrated that certain lncRNAs directly bound EZH2 and regulated EZH2 expression levels. A number of these lncRNAs that are associated with EZH2 may participate in NB tumorigenesis.

Epigenetic Silencing of miR-9 Promotes Migration and Invasion by EZH2 in Glioblastoma Cells

Glioblastoma (GBM) is the most common primary brain tumor in adults. Tumor invasion is the major reason for treatment failure and poor prognosis in GBM. Inhibiting migration and invasion has become an important therapeutic strategy for GBM treatment. Enhancer of zeste homolog 2 (EZH2) and C-X-C motif chemokine receptor 4 (CXCR4) have been determined to have important roles in the occurrence and development of tumors, but the specific relationship between EZH2 and CXCR4 expression in GBM is less well characterized. In this study, we report that EZH2 and CXCR4 were overexpressed in glioma patients. Furthermore, elevated EZH2 and CXCR4 were correlated with shorter disease-free survival. In three human GBM cell lines, EZH2 modulated the expression of miR-9, which directly targeted the oncogenic signaling of CXCR4 in GBM. The ectopic expression of miR-9 dramatically inhibited the migratory capacity of GBM cells in vitro. Taken together, our results indicate that miR-9, functioning as a tumor-suppressive miRNA in GBM, is suppressed through epigenetic silencing by EZH2. Thus, miR-9 may be an attractive target for therapeutic intervention in GBM.

Inhibition of EZH2 alleviates angiogenesis in a model of corneal neovascularization by blocking FoxO3a-mediated oxidative stress

Enhancer of zeste homolog 2 (EZH2), a well-known methyltransferase, mediates histone H3 lysine 27 trimethylation (H3K27me3) and plays a vital role in ophthalmological disease. However, its role in corneal neovascularization (CoNV) remains unclear. In vitro and in vivo models were assessed in hypoxia-stimulated angiogenesis and in a mouse model of alkali burn-induced CoNV. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions and different reoxygenation times to identify the molecular mechanisms involved in this process. In this study, we found that EZH2 was positively related to corneal alkali burn-induced injury. Inhibition of EZH2 with 3-Deazaneplanocin A (DZNeP) alleviated corneal injury, including oxidative stress and neovascularization in vivo. Similarly, inhibition of EZH2 with either DZNeP or small interfering RNA (siRNA) exerted an inhibitory effect on hypoxia/reoxygenation (H/R)-induced oxidative stress and angiogenesis in HUVECs. Moreover, our study revealed that ablation of reactive oxygen species (ROS) with N-acetyl-cysteine suppressed angiogenesis in HUVECs exposed to H/R stimulation. Furthermore, Forkhead-box protein O3a (FoxO3a), which was positively associated with ROS production and angiogenesis, was elevated during H/R. This effect could be reversed through the suppression of the transcription activity of EZH2 with DZNeP or siRNA. In addition, the PI3K/Akt pathway, which is the upstream of FoxO3a, was activated in both DZNeP-treated mice and EZH2-inhibited HUVECs. Collectively, our results demonstrated that the inhibition of EZH2 alleviated corneal angiogenesis by inhibiting FoxO3a-dependent ROS production through the PI3K/Akt signaling pathway. These findings indicate that EZH2 may be a valuable therapeutic target for CoNV.