Predicting the Correlation of EZH2 and Cancer Stem Cell Markers in Esophageal Squamous Cell Carcinoma

FBP1 knockdown decreases ovarian cancer formation and cisplatin resistance through EZH2-mediated H3K27me3

Worldwide, ovarian cancer (OC) is the seventh common cancer and the second most common cause of cancer death in women. Due to high rates of relapse, there is an urgent need for the identification of new targets for OC treatment. The far-upstream element binding protein 1 (FBP1) and enhancer of zeste homolog 2 (EZH2) are emerging proto-oncogenes that regulate cell proliferation and metastasis. In the present study, Oncomine data analysis demonstrated that FBP1 was closely associated with the development of OC, and The Cancer Genome Atlas (TCGA) data analysis indicated that there was a positive correlation between FBP1 and EZH2 in ovarian tissues. Moreover, we found that FBP1 knockdown suppressed tumor formation in nude mice and cisplatin resistance of OC cells, but the role of FBP1 in the cisplatin resistance of OC cells remained unclear. In addition, we verified physical binding between FBP1 and EZH2 in OC cells, and we demonstrated that FBP1 knockdown enhanced cisplatin cytotoxicity in OC cells and down-regulated EZH2 expression and trimethylation of H3K27. These results suggested that FBP1 increases cisplatin resistance of OC cells by up-regulating EZH2/H3K27me3. Thus, FBP1 is a prospective novel target for the development of OC treatment.

EZH2-mediated epigenetic suppression of SH3BGRL potently inhibits lung cancer progression

Lung cancer is the leading cause of cancer-related deaths worldwide. Lung cancer stem cells (CSCs) are a small population of cancer cells with self-renewal, therapeutic resistance, and tumor relapse capability. Yet the molecular mechanisms underlying lung CSCs self-renewal remain largely unknown. Here, we report that SH3BGRL were down-regulated in lung cancer tissues comparing with normal lung tissues and SH3BGRL low expression was correlated with the poor clinical outcomes of patients with lung cancer. Moreover, SH3BGRL was also weakly expressed in lung CSCs compared with its corresponding lung cancer cells. We first characterize that EZH2 directly binds to SH3BGRL promoter and transcriptional represses SH3BGRL expression in epigenetic level. Functionally, overexpression of SH3BGRL potently suppresses Lung CSCs self-renewal in vitro. The gain of function study reveals that SH3BGRL acts as a novel tumor suppressor via inhibiting lung cancer cell proliferation and migration as well as Lung CSCs self-renewal in vitro. Collectively, our work demonstrates that SH3BGRL hold potential as a favorable prognostic marker and therapeutic target for patients with lung cancer in future.

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.

LncRNA SNHG6 Inhibits Apoptosis by Regulating EZH2 Expression via the Sponging of MiR-101-3p in Esophageal Squamous-Cell Carcinoma

Background

The long non-coding RNA (lncRNA) SNHG6 was significantly upregulated in esophageal squamous-cell carcinoma (ESCC), and it promoted ESCC cell proliferation, invasion, and migration. However, the effects of SNHG6 on cell apoptosis and the corresponding underlying mechanisms have not yet reported.

Methods

Apoptosis was detected by flow cytometric analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were used for mRNA and protein quantification, respectively. A luciferase reporter assay was performed to verify downstream target genes for SNHG6 and miR-101-3p.

Results

Dysregulation of SNHG6 inhibited apoptosis in ESCC cells and regulated the expression of apoptosis-related proteins such as Bcl-2, Mcl-1, Bax and Caspase-3. Functionally, miR-101-3p could compete binding with 3′-untranslated region of SNHG6 and downregulation of miR-101-3p reversed its effect on cell apoptosis in SNHG6 knockdown cells. EZH2 was confirmed as a downstream target gene of miR-101-3p, silencing EZH2 expression had the same effect on apoptosis and protein expression as knocking down SNHG6. Overexpression of EZH2 reversed the effects of miR-101-3p overexpression on cell apoptosis in ESCC cells.

Conclusion

In this study, we found that upregulation of the lncRNA SNHG6 inhibited apoptosis via miR-101-3p/EZH2 axis in ESCC. These findings may contribute to the diagnosis and treatment of ESCC.

DUB3 Facilitates Growth and Inhibits Apoptosis Through Enhancing Expression of EZH2 in Oral Squamous Cell Carcinoma

Background

Here, we probed the action mechanism of ubiquitin-specific processing proteases 17 (DUB3) in the evolution of oral squamous cell carcinoma (OSCC).

Methods

The expression of genes were calculated by qRT-PCR, and proteins were assessed by Western blot and immunohistochemistry. The cells viability and proliferation were checked by MTT and EdU assay, respectively. Flow cytometry was implemented to detect the cell cycle and apoptosis. The activity of EZH2 gene promoter was measured by luciferase reporter assay. Co-immunoprecipitation assay was used to ensure the ubiquitination of bromodomain-containing protein 4 (BRD4). The cell apoptosis of tumor tissues was assessed by TUNEL assay.

Results

DUB3 was overexpressed in OSCC tissues and cell lines, and negatively correlated with patient’s survival time. DUB3 downregulation could effectively curb OSCC cells viability and proliferation, promote cell apoptosis and the expression of cleaved-caspase-3, cleaved PARP and p21, while inhibit cyclin D1. Besides, DUB3 production was positivity correlated with enhancer of zeste homolog-2 (EZH2) and BRD4. BRD4 downregulation could repress DUB3-induced EZH2 production, and MG132 reversed DUB3 decreasing-mediated BRD4 downregulation. Downregulation of DUB3 promoted BRD4 ubiquitination. DUB3 promoted OSCC cells proliferation, while suppressing apoptosis via facilitating EZH2 production. At last, in vivo experiment indicated that the downregulation of DUB3 significantly inhibited the growth of xenograft tumor.

Conclusion

In summary, we found that DUB3 enhanced OSCC cells proliferation and xenograft tumor growth, while inhibited their apoptosis via promoting BRD4-mediated upregulation of EZH2. Our study indicated that DUB3 may be an effective anti-cancer target for OSCC therapy.

Detention and Identification of Cancer Stem Cells in Esophageal Squamous Cell Carcinoma

Cancer stem cells (CSCs) are a small subpopulation of cells associated with cancer initiation, progression, metastasis, therapy resistant, and recurrence. In esophageal squamous cell carcinoma (ESCC), several cell surface and intracellular markers, for example, CD44, ALDH, Pygo2, MAML1, Twist1, Musashi1, side population (SP), CD271, and CD90, have been proposed to identify CSCs. In addition, stem cell markers such as ALDH1, HIWI, Oct3/4, ABCG2, SOX2, SALL4, BMI-1, NANOG, CD133, and podoplanin were associated with pathological stages of cancer, cancer recurrence, prognosis, and therapy resistance of patients with ESCC. Identification and isolation of CSCs could play an important part of improved cancer management regime in ESCC. Furthermore, CSCs may be used as the predictive tool for chemoradiotherapy response in ESCC. Different methods such as in vitro functional assays, cell sorting using various intracellular, and cell surface markers and xenotransplantation techniques are frequently used for the identification and isolation of CSCs in different cancers, including ESCC. However, none of these methods solely can guarantee complete isolation of CSC population. Therefore, a combination of methods is used for reliable detection and isolation of CSCs. Herein, we describe the identification and isolation of CSCs from ESCC cells by cell sorting after Hoechst 33342 staining followed by in vitro functional assays and in vivo mouse xenotransplantation techniques.

Epigenetic Profiling Identifies LIF as a Super-enhancer-Controlled Regulator of Stem Cell-like Properties in Osteosarcoma

Osteosarcoma is an aggressive malignancy with poor prognosis. Super-enhancers (SE) have been highlighted as critical oncogenic elements required for maintaining the cancer cell characteristics. However, the regulatory role of SEs in osteosarcoma properties has not yet been elucidated. In the current study, we found that osteosarcoma cells and clinical specimens shared a significant fraction of SEs. Moreover, leukemia-inhibitory factor (LIF) was identified as an essential factor under the control of osteosarcoma-specific SE. The expression of LIF was positively correlated with the stem cell core factor genes in osteosarcoma. Furthermore, LIF recombinant protein-treated osteosarcoma cells displayed enhanced stem cell-like characteristics, such as increased sphere-forming potential, stimulated self-renewal, upregulated metastasis ability, and increased stemness-related gene expression. Notably, the histone 3 lysine 27 tri-methylation (H3K27me3) demethylase UTX was found as a key activator of LIF transcription in osteosarcoma. The UTX inhibitor, GSK-J4, induced H3K27me3 accumulation and impaired histone 3 lysine 27 acetylation (H3K27ac) at LIF gene locus, leading to LIF signaling pathway inhibition. GSK-J4 treatment resulted in profound defects in stem cell-like characteristics and stemness-related gene activation in osteosarcoma by modulating the H3K27ac of NOTCH1 signaling pathway gene loci. The NOTCH1 inhibitor Crenigacestat (TargetMol, T3633) repressed LIF-mediated activation of the stemness-related genes in osteosarcoma patient-derived primary tissues. IMPLICATIONS: This study reveals osteosarcoma SE profiles and uncovers a distinct tumor-stemness epigenetic regulatory mechanism in which an osteosarcoma-specific SE-mediated factor, LIF, promotes osteosarcoma stemness gene activation via NOTCH1 signaling pathway.

EZH2 regulates H2B phosphorylation and elevates colon cancer cell autophagy

Epigenetic alterations, especially histone modification, play vital roles in the pathogenesis of colon cancer. Upregulation of the enhancer of zeste homolog 2 (EZH2) has been reported to contribute to the initiation and progression of colon cancer. This study analyzed the association between EZH2 and phosphorylation of H2B at tyrosine 37 (H2B^Y37ph ) in colon cancer tissues and cells, along with the influences of the EZH2-H2B^Y37ph axis on colon cancer cell autophagy. Immunohistochemistry was utilized to assess EZH2 and H2B^Y37ph expressions in clinical samples of colon cancer. Cell transfection was carried out to alter EZH2 and H2B^Y37ph expressions in colon cancer cells. Co-immunoprecipitation analysis and glutathione-S-transferase (GST) pull down assay were conducted to analyze the association between EZH2 and H2B^Y37ph . Western blotting was utilized to measure proteins expressions related to cell autophagy. We found that there was a positive association between EZH2 and H2B^Y37ph in colon cancer tissues and cells. EZH2 directly interacted with H2B and promoted H2B^Y37ph in colon cancer cells using ATP as a phosphate donor. Moreover, EZH2 levated colon cancer cell autophagy in starvation condition. H2B^Y37ph was required for EZH2-elevated colon cancer cell autophagy under starvation condition. The EZH2-H2B^Y37ph axis elevated colon cancer cell autophagy possibly via activating transcriptional regulation of ATG genes. In conclusion, EZH2-elevated colon cancer initiation and progression at least in part via inducing colon cancer cell autophagy. EZH2 could phosphorylate H2B^Y37 and then induce transcription activation of ATG genes in colon cancer cells under starvation condition.