The polycomb group protein EZH2 induces epithelial-mesenchymal transition and pluripotent phenotype of gastric cancer cells by binding to PTEN promoter

Horizontal transfer of the stemness-related markers EZH2 and GLI1 by neuroblastoma-derived extracellular vesicles in stromal cells

Neuroblastoma (NB) is the most common extracranial pediatric solid cancer originating from undifferentiated neural crest cells. NB cells express EZH2 and GLI1 genes that are known to maintain the undifferentiated phenotype of cancer stem cells (CSC) in NB. Recent studies suggest that tumor-derived extracellular vesicles (EVs) can regulate the transformation of surrounding cells into CSC by transferring tumor-specific molecules they contain. However, the horizontal transfer of EVs molecules in NB remains largely unknown. We report the analysis of NB-derived EVs in bioengineered models of NB that are based on a collagen 1/hyaluronic acid scaffold designed to mimic the native tumor niche. Using these models, we observed an enrichment of GLI1 and EZH2 mRNAs in NB-derived EVs. As a consequence of the uptake of NB-derived EVs, the host cells increased the expression levels of GLI1 and EZH2. These results suggest the alteration of the expression profile of stromal cells through an EV-based mechanism, and point the GLI1 and EZH2 mRNAs in the EV cargo as diagnostic biomarkers in NB.

LINC00511 promotes gastric cancer progression by regulating SOX4 and epigenetically repressing PTEN to activate PI3K/AKT pathway

Gastric cancer (GC) serves as a common malignancy. Long non-coding RNAs (lncRNAs) have been proven to regulate many cancers, including GC. Long intergenic non-protein-coding RNA 511 (LINC00511) has been poorly studied in GC, but its detailed regulatory mechanism has not been identified. Here, LINC00511 was detected to be highly expressed in GC cells. Functional assays were conducted and uncovered that LINC00511 boosted cell proliferation, migration, stemness and EMT process while inhibiting the apoptosis of GC cells. From a series of mechanism experiments, it was found that at the transcriptional level, LINC00511 recruited EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit) to the promoter of PTEN (phosphatase and tensin homolog) and facilitated methylation of PTEN promoter. LINC00511 epigenetically repressed PTEN to activate the PI3K/AKT pathway. Moreover, SRY-box transcription factor 4 (SOX4) activated the transcription of LINC00511. At the post-transcriptional level, LINC00511 sponged miR-195-5p to elevate SOX4 expression in GC cells. On the whole, the present study disclosed that SOX4-induced LINC00511 activated SOX4 via competing endogenous RNA (ceRNA) pattern and epigenetically repressed PTEN to activate PI3K/AKT pathway by recruiting EZH2, thus facilitating GC cell proliferation, migration and stemness while inhibiting GC cell apoptosis.

Identification and Validation of the Immune Regulator CXCR4 as a Novel Promising Target for Gastric Cancer

Immune checkpoint blockade has attracted a lot of attention in the treatment of human malignant tumors. We are trying to establish a prognostic model of gastric cancer (GC) based on the expression profile of immunoregulatory factor-related genes. Based on the TCGA database, we identified 234 differentially expressed immunoregulatory factors. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) conducted enrichment analysis to clarify the biological functions of differential expression of immunoregulatory factors. STRING database predicted the interaction network between 234 differently expressed immune regulatory factors. The expression of 11 immunoregulatory factors was significantly related to the overall survival of gastric cancer patients. Univariate Cox regression analysis, Kaplan–Meier analysis and multivariate Cox regression analysis found that immunomodulatory factors were involved in the progression of gastric cancer and promising biomarkers for predicting prognosis. Among them, CXCR4 was related to the low survival of GC patients and a key immunomodulatory factor in GC. Based on TCGA data, the high expression of CXCR4 in GC was positively correlated with the advanced stage and grade of gastric cancer and related to poor prognosis. Univariate analysis and multivariate analysis indicated that CXCR4 was an independent prognostic indicator for TCGA gastric cancer patients. In vitro functional studies had shown that CXCR4 promoted the proliferation, migration, and invasion of gastric cancer cells. In summary, this study has determined the prognostic value of 11 immunomodulatory factors in gastric cancer. CXCR4 is an independent prognostic indicator for gastric cancer patients, which may help to improve the individualized prognostic prediction of GC and provide candidates for the diagnosis and treatment of GC.

Morphological screening of mesenchymal mammary tumor organoids to identify drugs that reverse epithelial-mesenchymal transition

The epithelial-mesenchymal transition (EMT) has been implicated in conferring stem cell properties and therapeutic resistance to cancer cells. Therefore, identification of drugs that can reprogram EMT may provide new therapeutic strategies. Here, we report that cells derived from claudin-low mammary tumors, a mesenchymal subtype of triple-negative breast cancer, exhibit a distinctive organoid structure with extended "spikes" in 3D matrices. Upon a miR-200 induced mesenchymal-epithelial transition (MET), the organoids switch to a smoother round morphology. Based on these observations, we developed a morphological screening method with accompanying analytical pipelines that leverage deep neural networks and nearest neighborhood classification to screen for EMT-reversing drugs. Through screening of a targeted epigenetic drug library, we identified multiple class I HDAC inhibitors and Bromodomain inhibitors that reverse EMT. These data support the use of morphological screening of mesenchymal mammary tumor organoids as a platform to identify drugs that reverse EMT.

Epigenetic regulation of cancer stem cell formation and maintenance

Cancerous tumours contain a rare subset of cells with stem-like properties that are termed cancer stem cells (CSCs). CSCs are defined by their ability to divide both symmetrically and asymmetrically, to initiate new tumour growth and to tolerate the foreign niches required for metastatic dissemination. Accumulating evidence suggests that tumours arise from cells with stem-like properties, the generation of CSCs is therefore likely to be an initiatory event in carcinogenesis. Furthermore, CSCs in established tumours exist in a dynamic and plastic state, with nonstem tumour cells thought to be capable of de-differentiation to CSCs. The regulation of the CSC state both during tumour initiation and within established tumours is a desirable therapeutic target and is mediated by epigenetic factors. In this review, we will explore the epigenetic parallels between induced pluripotency and the generation of CSCs, and discuss how the epigenetic regulation of CSCs opens up novel opportunities for therapeutic intervention.

The Role of HECT-Type E3 Ligase in the Development of Cardiac Disease

Despite advances in medicine, cardiac disease remains an increasing health problem associated with a high mortality rate. Maladaptive cardiac remodeling, such as cardiac hypertrophy and fibrosis, is a risk factor for heart failure; therefore, it is critical to identify new therapeutic targets. Failing heart is reported to be associated with hyper-ubiquitylation and impairment of the ubiquitin–proteasome system, indicating an importance of ubiquitylation in the development of cardiac disease. Ubiquitylation is a post-translational modification that plays a pivotal role in protein function and degradation. In 1995, homologous to E6AP C-terminus (HECT) type E3 ligases were discovered. E3 ligases are key enzymes in ubiquitylation and are classified into three families: really interesting new genes (RING), HECT, and RING-between-RINGs (RBRs). Moreover, 28 HECT-type E3 ligases have been identified in human beings. It is well conserved in evolution and is characterized by the direct attachment of ubiquitin to substrates. HECT-type E3 ligase is reported to be involved in a wide range of human diseases and health. The role of HECT-type E3 ligases in the development of cardiac diseases has been uncovered in the last decade. There are only a few review articles summarizing recent advancements regarding HECT-type E3 ligase in the field of cardiac disease. This study focused on cardiac remodeling and described the role of HECT-type E3 ligases in the development of cardiac disease. Moreover, this study revealed that the current knowledge could be exploited for the development of new clinical therapies.

Cell Plasticity and Prostate Cancer: The Role of Epithelial-Mesenchymal Transition in Tumor Progression, Invasion, Metastasis and Cancer Therapy Resistance

Simple Summary

Although epithelial-to-mesenchymal transition (EMT) is a well-known cellular process involved during normal embryogenesis and wound healing, it also has a dark side; it is a complex process that provides tumor cells with a more aggressive phenotype, facilitating tumor metastasis and even resistance to therapy. This review focuses on the key pathways of EMT in the pathogenesis of prostate cancer and the development of metastases and evasion of currently available treatments.

Abstract

Prostate cancer, the second most common malignancy in men, is characterized by high heterogeneity that poses several therapeutic challenges. Epithelial–mesenchymal transition (EMT) is a dynamic, reversible cellular process which is essential in normal embryonic morphogenesis and wound healing. However, the cellular changes that are induced by EMT suggest that it may also play a central role in tumor progression, invasion, metastasis, and resistance to current therapeutic options. These changes include enhanced motility and loss of cell–cell adhesion that form a more aggressive cellular phenotype. Moreover, the reverse process (MET) is a necessary element of the metastatic tumor process. It is highly probable that this cell plasticity reflects a hybrid state between epithelial and mesenchymal status. In this review, we describe the underlying key mechanisms of the EMT-induced phenotype modulation that contribute to prostate tumor aggressiveness and cancer therapy resistance, in an effort to provide a framework of this complex cellular process.

EPHA3 Contributes to Epigenetic Suppression of PTEN in Radioresistant Head and Neck Cancer

EPHA3, a member of the EPH family, is overexpressed in various cancers. We demonstrated previously that EPHA3 is associated with radiation resistance in head and neck cancer via the PTEN/Akt/EMT pathway; the inhibition of EPHA3 significantly enhances the efficacy of radiotherapy in vitro and in vivo. In this study, we investigated the mechanisms of PTEN regulation through EPHA3-related signaling. Increased DNA methyltransferase 1 (DNMT1) and enhancer of zeste homolog 2 (EZH2) levels, along with increased histone H3 lysine 27 trimethylation (H3K27me3) levels, correlated with decreased levels of PTEN in radioresistant head and neck cancer cells. Furthermore, PTEN is regulated in two ways: DNMT1-mediated DNA methylation, and EZH2-mediated histone methylation through EPHA3/C-myc signaling. Our results suggest that EPHA3 could display a novel regulatory mechanism for the epigenetic regulation of PTEN in radioresistant head and neck cancer cells.

Amplification and expression of c-MET correlate with poor prognosis of patients with gastric cancer and upregulate the expression of PDL1

The prognostic significance of c-MET in gastric cancer (GC) remains uncertain. In the present study, we examined the amplification, expression, and the prognostic value of c-MET, human epidermal growth factor receptor 2 (HER2), and programmed cell death 1 ligand 1 (PDL1), together with the correlations among them in a large cohort of Chinese samples. A total of 444 patients were included. The immunohistochemistry (IHC) and the dual-color silver in situ hybridization (SISH) were performed to examine their expression and amplification. Univariate and multivariate analyses were performed by the Cox proportional hazard regression model, and survival curves were estimated by the Kaplan-Meier method. The positivity determined by IHC of c-MET was 24.8%, and the MET amplification rate was 2.3%. The positivity rates of HER2 and PDL1 were 8% and 34.7%, respectively. PDL1 expression had a significantly positive association with c-MET expression. c-MET positivity played a significant prognostic role in disease-free survival (DFS) (P = 0.032). Patients with mesenchymal-epithelial transition (MET) amplification had significantly poorer prognosis on both DFS and overall survival (OS). Subgroup analysis showed that in HER2-negative patients, but not in HER2-positive patients, MET-positive patients had significantly worse DFS (P = 0.000) and OS (P = 0.006). c-MET regulated the expression of PDL1 through an AKT-dependent pathway. c-MET inhibitor enhanced the T-cell killing ability and increased the efficacy of PD1 antibody. c-MET was found to be an independent prognostic factor for DFS of GC patients. A combination of c-MET inhibitors and PD1 antibodies could enhance the killing capacity of T cells, providing a preliminary basis for the clinical research on the same combination in GC treatment.

Progress in research of EZH2 in digestive system tumors

EZH2 is a key member of the PcG protein family and a subunit of catalytic activity in the PRC2 complex. It has histone methylation transferase activity and plays an important role in epigenetic modification. A large number of studies have shown that it is closely related to the occurrence, development, and prognosis of various digestive system tumors and is highly expressed in tumor tissues, such as gastric cancer, liver cancer, colorectal cancer, pancreatic cancer, and gallbladder cancer. In this paper, we review the biological characteristics of EZH2d , its role in digestive system tumors, and the prospect of targeted therapy for EZH2.

Short-form RON (sf-RON) enhances glucose metabolism to promote cell proliferation via activating β-catenin/SIX1 signaling pathway in gastric cancer

Recepteur d'origine nantais (RON) has been implicated in cell proliferation, metastasis, and chemoresistance of various human malignancies. The short-form RON (sf-RON) encoded by RON transcripts was overexpressed in gastric cancer tissues, but its regulatory functions remain illustrated. Here, we found that sf-RON promoted gastric cancer cell proliferation by enhancing glucose metabolism. Furthermore, sf-RON was proved to induce the β-catenin expression level through the AKT1/GSK3β signaling pathway. Meanwhile, the binding sites of β-catenin were identified in the promoter region of SIX1 and it was also demonstrated that β-catenin positively regulated SIX1 expression. SIX1 enhanced the promoter activity of key proteins in glucose metabolism, such as GLUT1 and LDHA. Results indicated that sf-RON regulated the cell proliferation and glucose metabolism of gastric cancer by participating in a sf-RON/β-catenin/SIX1 signaling axis and had significant implications for choosing the therapeutic target of gastric cancer.

EMT-associated microRNAs and their roles in cancer stemness and drug resistance

Epithelial‐to‐mesenchymal transition (EMT) is implicated in a wide array of malignant behaviors of cancers, including proliferation, invasion, and metastasis. Most notably, previou studies have indicated that both cancer stem‐like properties and drug resistance were associated with EMT. Furthermore, microRNAs (miRNAs) play a pivotal role in the regulation of EMT phenotype, as a result, some miRNAs impact cancer stemness and drug resistance. Therefore, understanding the relationship between EMT‐associated miRNAs and cancer stemness/drug resistance is beneficial to both basic research and clinical treatment. In this review, we preliminarily looked into the various roles that the EMT‐associated miRNAs play in the stem‐like nature of malignant cells. Then, we reviewed the interaction between EMT‐associated miRNAs and the drug‐resistant complex signaling pathways of multiple cancers including lung cancer, gastric cancer, gynecologic cancer, breast cancer, liver cancer, colorectal cancer, pancreatic cancer, esophageal cancer, and nasopharyngeal cancer. We finally discussed the relationship between EMT, cancer stemness, and drug resistance, as well as looked forward to the potential applications of miRNA therapy for malignant tumors.

Ultrasound-Targeted Microbubble Destruction-Mediated Downregulation of EZH2 Inhibits Stemness and Epithelial-Mesenchymal Transition of Liver Cancer Stem Cells

Background

Cancer cells could show the characteristics of cancer stem cells (CSCs) through epithelial-mesenchymal transition (EMT). EZH2 was associated with EMT. Ultrasound-targeted microbubble destruction (UTMD) could enhance gene transfection efficiency. Here, we explored the effect of UTMD-mediated shEZH2 on liver CSCs.

Methods

EZH2 expression in liver cancer and the overall survival of liver cancer patients were analyzed by bioinformatics. Liver CSCs (CD133⁺HuH7) were sorted by flow cytometry. After transfection of shEZH2 through UTMD (UTMD-shEZH2) or liposome (LIP-shEZH2), the viability, proliferation, sphere formation, migration, and invasion of CD133⁺HuH7 cells were detected by MTT, colony formation, tumor-sphere formation, wound healing, and transwell assays, respectively. A mice subcutaneous-xenotransplant tumor model was established by injecting CD133⁺HuH7 or CD133⁻HuH7 cells into the limbs of mice. Tumor weight and volume were documented. The expressions of EZH2, EMT-related factors, and STAT3/PI3K/AKT pathway-related factors in CD133⁺HuH7 cells or tumor tissues were detected by RT-qPCR, Western blot, or immunohistochemical.

Results

EZH2 was high-expressed in liver cancer, and the patients with high expression of EZH2 had a poor survival. CD133⁺ HuH7 cells had higher EZH2 expression, higher viability, and stronger sphere-forming and tumor-forming abilities than CD133⁻ HuH7 cells. ShEZH2 inhibited the viability, proliferation, sphere formation, migration, and invasion of CD133⁺ HuH7 cells, decreased the weight and volume of the xenotransplant tumor, inhibited the expressions of EZH2, Vimentin, N-Cadherin, Twist-1, p-STAT3, p-PI3K, and p-AKT, and increased E-Cadherin expression. UTMD-shEZH2 caused a stronger effect on CD133⁺ HuH7 cells than LIP-shEZH2.

Conclusion

UTMD-mediated shEZH2 inhibited the stemness and EMT of liver CSCs in vitro and in vivo through regulating the STAT3/PI3K/AKT pathway.

BTEB2-Activated lncRNA TSPEAR-AS2 Drives GC Progression through Suppressing GJA1 Expression and Upregulating CLDN4 Expression

Long non-coding RNAs (lncRNAs) are characterized as key layers of the genome in various cancers. TSPEAR-AS2 was highlighted to be a candidate lncRNA potentially involved in gastric cancer (GC) progression. However, the clinical significance and mechanism of TSPEAR-AS2 in GC required clarification. The clinical significance of TSPEAR-AS2 was elucidated through Kaplan-Meier Plotter. The mechanism of TSPEAR-AS2 in GC was clarified in vitro and in vivo using luciferase reporter, chromatin immunoprecipitation, RNA immunoprecipitation assays, and animal models. TSPEAR-AS2 elevation was closely correlated with overall survival of GC patients. A basic transcription element-binding protein 2 (BTEB2)-activated TSPEAR-AS2 model was first explored in this study. TSPEAR-AS2 silencing substantially reduced tumorigenic capacities of GC cells, while TSPEAR-AS2 elevation had the opposite effect. Mechanistically, TSPEAR-AS2 bound with both polycomb repressive complex 2 (PRC2) and argonaute 2 (Ago2). TSPEAR-AS2 knockdown significantly decreased H3K27me3 levels at promoter regions of gap junction protein alpha 1 (GJA1). Ago2 was recruited by TSPEAR-AS2, which was defined to sponge miR-1207-5p, contributing to the repression of claudin 4 (CLDN4) translation. The axis of EZH2/GJA1 and miR-1207-5p/CLDN4 mediated by BTEB2-activated-TSPEAR-AS2 plays an important role in GC progression, suggesting a new therapeutic direction in GC treatment.

Novel molecular targets in gastric adenocarcinoma

Gastric adenocarcinoma (GAC) is the third leading cause of cancer-related death worldwide. A high mortality rate and resistance to treatment protocols due to a heterogeneous molecular pathogenesis has made discovering the key etiologic molecular alterations of the utmost importance. The remarkable role played by epigenetic modifications in repressing or activating many cancer-related genes and forming new epigenetic signatures can affect cancer initiation and progression. Hence, targeting the key epigenetic drivers could potentially attenuate cancer progression. MLLs, ARID1A and EZH2 are among the major epigenetic players that are frequently mutated in GACs. In this paper, we have proposed the existence of a network between these proteins that, together with PCAF and KDM6A, control the 3D chromatin structure and regulate the expression of tumor suppressor genes (TSGs) and oncogenes in GAC. Therefore, we suggest that manipulating the expression of EZH2, PCAF, and KDM6A or their downstream targets may reduce the cancerous phenotype in GAC.

Exosome-Delivered LncHEIH Promotes Gastric Cancer Progression by Upregulating EZH2 and Stimulating Methylation of the GSDME Promoter

Gastric cancer is the third leading cause of cancer-related deaths worldwide and is characterized by poor survival and high recurrence rates. Long non-coding RNAs (lncRNAs) have gained considerable attention in recent years as prognostic markers and gene regulators in various cancers. Here, we found that lncHEIH was upregulated in gastric cancer tissues and cell lines and positively correlated with high expression levels of EZH2. Mechanistically, the lncHEIH-EZH2 axis could promote the progression of gastric cancer. In addition, lncHEIH encapsulated in exosomes was released by gastric cancer cells and then absorbed by normal gastric cells. The uptake of lncHEIH resulted in the upregulation of EZH2, which inhibited the expression of the tumor suppressor GSDME by methylation of the GSDME promoter, promoting the malignant transformation of normal gastric cells. Overall, lncHEIH promotes gastric cancer progression by upregulating the expression of EZH2 and reducing the expression of GSDME in normal cells to induce malignant cell proliferation and migration, indicating its potential as a target in gastric cancer therapy.

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.

Exosome-transferred LINC01559 promotes the progression of gastric cancer via PI3K/AKT signaling pathway

Increasing evidence indicates that long non-coding RNAs (lncRNAs) are associated with the progression of human cancers. However, the expression level and function of LINC01559 (long intergenic non-protein coding RNA 1559) in gastric cancer (GC) are rarely reported. Here we found that LINC01559 was upregulated in GC tissues based on GEPIA (Gene Expression Profiling Interactive Analysis) and TCGA (The Cancer Genome Atlas) databases. Also, LINC01559 was expressed at a lower level in GC cells than in mesenchymal stem cells (MSCs). In vitro experiments revealed that silencing LINC01559 remarkably hindered GC cell proliferation, migration and stemness. Then, we identified that LINC01559 was transmitted form MSCs to GC cells via the exosomes. Immunofluorescence staining and electron microscope validated the existence of exosomes in GC cells. Mechanistically, LINC01559 sponged miR-1343-3p to upregulate PGK1 (phosphoglycerate kinase 1), therefore activating PI3K/AKT pathway. Moreover, LINC01559 recruited EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit) to PTEN (phosphatase and tensin homolog) promoter, inducing the methylation of PTEN promoter and finally resulting in PTEN repression. Of note, LINC01559 targeted both PGK1 and PTEN to promote GC progression by activating PI3K/AKT pathway. Taken together, our study demonstrated that LINC01559 accelerated GC progression via upregulating PGK1 and downregulating PTEN to trigger phosphatidylinositol 3-kinase/AKT serine/threonine kinase (PI3K/AKT) pathway, indicating LINC01559 as a potential biomarker for GC treatment.

E2F7-EZH2 axis regulates PTEN/AKT/mTOR signalling and glioblastoma progression

BACKGROUND

E2F transcription factors are considered to be important drivers of tumour growth. E2F7 is an atypical E2F factor, and its role in glioblastoma remains undefined.

METHODS

E2F7 expression was examined in patients by IHC and qRT-PCR. The overall survival probability was determined by statistical analyses. MTT assay, colony formation, cell-cycle assay, cell metastasis and the in vivo model were employed to determine the functional role of E2F7 in glioblastoma. Chromatin immunoprecipitation, luciferase assay and western blot were used to explore the underlying mechanisms.

RESULTS

E2F7 was found to be up-regulated in glioblastoma patients, and high E2F7 expression was associated with poor overall survival in glioblastoma patients. Functional studies showed that E2F7 promoted cell proliferation, cell-cycle progression, cell metastasis and tumorigenicity abilities in vitro and in vivo. E2F7 promoted the transcription of EZH2 by binding to its promoter and increased H3K27me3 level. EZH2 recruited H3K27me3 to the promoter of PTEN and inhibited PTEN expression, and then activated the AKT/mTOR signalling pathway. In addition, restored expression of EZH2 recovered the abilities of cell proliferation and metastasis in E2F7-silencing cells.

CONCLUSION

Collectively, our findings indicate that E2F7 promotes cell proliferation, cell metastasis and tumorigenesis via EZH2-mediated PTEN/AKT/mTOR pathway in glioblastoma.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

The role of histone methylation in the development of digestive cancers: a potential direction for cancer management

Digestive cancers are the leading cause of cancer-related death worldwide and have high risks of morbidity and mortality. Histone methylation, which is mediated mainly by lysine methyltransferases, lysine demethylases, and protein arginine methyltransferases, has emerged as an essential mechanism regulating pathological processes in digestive cancers. Under certain conditions, aberrant expression of these modifiers leads to abnormal histone methylation or demethylation in the corresponding cancer-related genes, which contributes to different processes and phenotypes, such as carcinogenesis, proliferation, metabolic reprogramming, epithelial–mesenchymal transition, invasion, and migration, during digestive cancer development. In this review, we focus on the association between histone methylation regulation and the development of digestive cancers, including gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer, as well as on its clinical application prospects, aiming to provide a new perspective on the management of digestive cancers.

EZH2: a novel target for cancer treatment

Enhancer of zeste homolog 2 (EZH2) is enzymatic catalytic subunit of polycomb repressive complex 2 (PRC2) that can alter downstream target genes expression by trimethylation of Lys-27 in histone 3 (H3K27me3). EZH2 could also regulate gene expression in ways besides H3K27me3. Functions of EZH2 in cells proliferation, apoptosis, and senescence have been identified. Its important roles in the pathophysiology of cancer are now widely concerned. Therefore, targeting EZH2 for cancer therapy is a hot research topic now and different types of EZH2 inhibitors have been developed. In this review, we summarize the structure and action modes of EZH2, focusing on up-to-date findings regarding the role of EZH2 in cancer initiation, progression, metastasis, metabolism, drug resistance, and immunity regulation. Furtherly, we highlight the advance of targeting EZH2 therapies in experiments and clinical studies.

The interaction of interleukin-8 and PTEN inactivation promotes the malignant progression of head and neck squamous cell carcinoma via the STAT3 pathway

Interleukin-8 (IL-8) expression correlates with poor prognosis in many cancers, including head and neck squamous cell carcinoma (HNSCC), but the underlying mechanism is poorly understood. In this study, we found that overexpression of IL-8 correlated with poor outcome in HNSCC patients. IL-8 significantly increased cellular proliferation, migration, and invasion ability both in vitro and in vivo, which could be blocked by a CXCR1/2 inhibitor. IL-8 promoted the expression of MMP2, MMP9, snail, and vimentin in HNSCC cells. Furthermore, IL-8 could inactivate PTEN via phosphorylation, and then inactivated PTEN affected the phosphorylation of STAT3. Recombinant PTEN that internalized in cytoplasm decreased the expression of phosphorylated STAT3, while knockdown of PTEN led to the increased expression of phosphorylated STAT3. A STAT3 inhibitor could reverse the upregulation of invasion-associated proteins mediated by IL-8 stimulation. Furthermore, overexpression of snail and inactivated PTEN jointly promoted the autocrine effect of IL-8 on tumor cells. Last, there were positive correlations between IL-8 and snail, vimentin expression in HNSCC tissues. In summary, our study demonstrates that PTEN acts as a novel "molecular switch" to regulate IL-8/STAT3 signaling, promoting the progression of HNSCC, and indicating that this pathway may be a potential therapeutic target for HNSCC.

Mechanisms of the Epithelial-Mesenchymal Transition and Tumor Microenvironment in Helicobacter pylori-Induced Gastric Cancer

Helicobacter pylori (H. pylori) is one of the most common human pathogens, affecting half of the world’s population. Approximately 20% of the infected patients develop gastric ulcers or neoplastic changes in the gastric stroma. An infection also leads to the progression of epithelial–mesenchymal transition within gastric tissue, increasing the probability of gastric cancer development. This paper aims to review the role of H. pylori and its virulence factors in epithelial–mesenchymal transition associated with malignant transformation within the gastric stroma. The reviewed factors included: CagA (cytotoxin-associated gene A) along with induction of cancer stem-cell properties and interaction with YAP (Yes-associated protein pathway), tumor necrosis factor α-inducing protein, Lpp20 lipoprotein, Afadin protein, penicillin-binding protein 1A, microRNA-29a-3p, programmed cell death protein 4, lysosomal-associated protein transmembrane 4β, cancer-associated fibroblasts, heparin-binding epidermal growth factor (HB-EGF), matrix metalloproteinase-7 (MMP-7), and cancer stem cells (CSCs). The review summarizes the most recent findings, providing insight into potential molecular targets and new treatment strategies for gastric cancer.

Exosome-transmitted lncRNA UFC1 promotes non-small-cell lung cancer progression by EZH2-mediated epigenetic silencing of PTEN expression

Long non-coding RNAs (LncRNAs) have been suggested as important regulators of cancer development and progression in non-small cell lung cancer (NSCLC). Nevertheless, the biological roles and clinical significance of lncRNA UFC1 in NSCLC remain unclear. We detected the expression of UFC1 in tumor tissues, serum, and serum exosomes of NSCLC patients by qRT-PCR. Gene overexpression or silencing were used to examine the biological roles of UFC1 in NSCLC. RNA immunoprecipitation and ChIP assays were performed to evaluate the interaction between UFC1 and enhancer of zeste homolog 2 (EZH2) and the binding of EZH2 to PTEN gene promoter. Rescue study was used to access the importance of PTEN regulation by UFC1 in NSCLC progression. UFC1 expression was upregulated in tumor tissues, serum, and serum exosomes of NSCLC patients and high level of UFC1 was associated with tumor infiltration. UFC1 knockdown inhibited NSCLC cell proliferation, migration and invasion while promoted cell cycle arrest and apoptosis. UFC1 overexpression led to the opposite effects. Mechanistically, UFC1 bound to EZH2 and mediated its accumulation at the promoter region of PTEN gene, resulting in the trimethylation of H3K27 and the inhibition of PTEN expression. UFC1 knockdown inhibited NSCLC growth in mouse xenograft tumor models while the simultaneous depletion of PTEN reversed this effect. NSCLC cells derived exosomes could promote NSCLC cell proliferation, migration and invasion through the transfer of UFC1. Moreover, Exosome-transmitted UFC1 promotes NSCLC progression by inhibiting PTEN expression via EZH2-mediated epigenetic silencing. Exosome-mediated transmit of UFC1 may represent a new mechanism for NSCLC progression and provide a potential marker for NSCLC diagnosis.

A TGF-β-MTA1-SOX4-EZH2 signaling axis drives epithelial-mesenchymal transition in tumor metastasis

MTA1, SOX4, EZH2, and TGF-β are all potent inducers of epithelial-mesenchymal transition (EMT) in cancer; however, the signaling relationship among these molecules in EMT is poorly understood. Here, we investigated the function of MTA1 in cancer cells and demonstrated that MTA1 overexpression efficiently activates EMT. This activation resulted in a significant increase in the migratory and invasive properties of three different cancer cell lines through a common mechanism involving SOX4 activation, screened from a gene expression profiling analysis. We showed that both SOX4 and MTA1 are induced by TGF-β and both are indispensable for TGF-β-mediated EMT. Further investigation identified that MTA1 acts upstream of SOX4 in the TGF-β pathway, emphasizing a TGF-β-MTA1-SOX4 signaling axis in EMT induction. The histone methyltransferase EZH2, a component of the polycomb (PcG) repressive complex 2 (PRC2), was identified as a critical responsive gene of the TGF-β-MTA1-SOX4 signaling in three different epithelial cancer cell lines, suggesting that this signaling acts broadly in cancer cells in vitro. The MTA1-SOX4-EZH2 signaling cascade was further verified in TCGA pan-cancer patient samples and in a colon cancer cDNA microarray, and activation of genes in this signaling pathway predicted an unfavorable prognosis in colon cancer patients. Collectively, our data uncover a SOX4-dependent EMT-inducing mechanism underlying MTA1-driven cancer metastasis and suggest a widespread TGF-β-MTA1-SOX4-EZH2 signaling axis that drives EMT in various cancers. We propose that this signaling may be used as a common therapeutic target to control epithelial cancer metastasis.

MiRNA-506 presents multiple tumor suppressor activities by targeting EZH2 in nasopharyngeal carcinoma

OBJECTIVE

MiR-506 has been reported to be associated with multiple malignancies, but its roles in nasopharyngeal cancer (NPC) are not fully understood. Our objective is to demonstrate its effects on NPC and the underlying mechanisms.

METHODS

Totally fifteen pairs of NPC and adjacent non-tumorous tissues were collected for the detection of miR-506 and enhancer of zeste homolog 2 (EZH2) expression. Dual luciferase reporter assay was employed for verifying the relationship between miR-506 and EZH2. The flow cytometry and MTT assays were employed to explore the effects of miR-506 and EZH2 on the cell apoptosis and proliferation, respectively. Wound closure and transwell assays were used to evaluate the cell migration and invasion abilities. Western blotting or RT-qPCR assays were applied to detect the alterations of miR-506, EZH2 and epithelial-mesenchymal transition (EMT)-related markers. Morphological changes of cells with EMT were assessed by light microscopy.

RESULTS

MiR-506 was significantly decreased and EZH2 was obviously increased in NPC tissues. Overexpression of miR-506 decreased the EZH2 level, promoted apoptosis, inhibited proliferation, invasion and migration of NPC cells. Accordingly, miR-506 overexpression attenuated EMT process of NPC cells as demonstrated by the alterations of EMT-related markers and the morphological changes. In addition, the luciferase assay proved that miR-506 directly targeted EZH2. Furthermore, the overexpression of EZH2 reversed the tumor-suppressive effects induced by miR-506 mimics.

CONCLUSION

MiR-506 acted as a tumor suppressor to promote apoptosis and inhibit invasion and migration via directly targeting EZH2. MiR-506 can be a candidate target for gene therapy against NPC.

LncRNA GAS5 facilitates nasopharyngeal carcinoma progression through epigenetically silencing PTEN via EZH2

Increasing evidence demonstrated that long non-coding RNA growth-arrest-specific transcript 5 (GAS5) serves as a critical regulator in cancer development and progression. However, its function and mechanism in nasopharyngeal carcinoma (NPC) is still not well elucidated. In this study, we investigate the functional role as well as the molecular mechanism of GAS5 in NPC progression. Our results indicated that GAS5 expression was elevated in NPC tissues and cells. High GAS5 expression was correlated with poor prognosis of NPC patients. GAS5 knockdown suppressed proliferation, migration and invasion, and induced apoptosis in NPC cells. Moreover, GAS5 could epigenetically suppress PTEN expression via recruiting enhancer of zeste homolog 2 (EZH2). PTEN knockdown could reverse the inhibitory effect of GAS5 inhibition on NPC progression. Furthermore, GAS5 knockdown suppressed the tumor growth in vivo. In summary, knockdown of GAS5 repressed proliferation, migration and invasion, and promoted apoptosis in NPC through epigenetically silencing PTEN via recruiting EZH2.

TRIB3 promotes lung cancer progression by activating β-catenin signaling

TRIB3 roles in tumor progression have been revealed with similar or opposite results. Here, we found that TRIB3 expression was highly expressed in lung cancer tissues and correlated with tumor grades and metastasis. Functional experiments showed that TRIB3 knockdown (KD) inhibited lung cancer cell migration, invasion, EMT (epithelial-mesenchymal transition) process and stemness. Mechanistic studies demonstrated that TRIB3 physically interacted with β-catenin and increased the recruitment of β-catenin to the promoter region of genes regulated by Wnt. Re-activation of β-catenin attenuated the inhibition of TRIB3 KD on lung cancer progression. These results suggest that TRIB3 interacts with β-catenin and thus activates β-catenin signaling, which is responsible for lung cancer progression, and blocking TRIB3 activity might be developed to treat lung cancer.

Epigenetics mechanisms mediate the miR-125a/BRMS1 axis to regulate invasion and metastasis in gastric cancer

Purpose

Altered expression of breast cancer metastasis suppressor 1 (BRMS1), is a tumor suppressor, which is found in many types of cancers, including gastric cancer (GC), but the mechanism by which BRMS1 inhibits invasion and metastasis in GC is unknown. The aim of the study was to investigate the molecular mechanisms of miR-125a/BRMS1 in GC.

Materials and methods

The expression of BRMS1 and miR-125a were detected by quantitative real-time PCR (qRT-PCR) and analyzed by bioinformatics. BSP and MSP were used to detecte the methylation status of miR-125a and BRMS1 which was treated by 5-Aza or not. Western Blot and qRT-PCR were used to analyze the expression of BRMS1 and EZH2. Transwell was performed to explore the invasion and metastasis ability of GC cells. The nude mice were used for the tumor formation assay.

Results

BRMS1 may be regulated by copy number variation (CNV), methylation and miR-125a-5p. As one of the essential components of PRC2, EZH2 is an important regulatory factor resulting in the low expression of miR-125a. An epigenetic mechanism mediates the miR-125a/BRMS1 axis to inhibit the invasion and metastasis of GC cells. In vivo experiments, it is also showed that BRMS1 is involved in invasion and metastasis but not the proliferation in GC.

Conclusion

These studies shed light on the mechanism of BRMS1 inhibition of GC invasion and metastasis and the development of new drugs targeting the miR-125a/BRMS1 axis, which will be a promising therapeutic strategy for GC and other human cancers.

PCAT-1 contributes to cisplatin resistance in gastric cancer through epigenetically silencing PTEN via recruiting EZH2

The aim of this study was to investigate the functional role and the underlying molecular mechanism of long noncoding RNA (lncRNA) prostate cancer-associated transcript 1 (PCAT-1) in cisplatin resistance of gastric cancer (GC). Our results indicated that PCAT-1 was overexpressed in CDDP-resistant GC tumor tissues and cell lines. High expression of PCAT-1 was closely correlated with short overall survival in patients with GC. Downregulation of PCAT-1 resensitized CDDP-resistant GC cells to cisplatin. In addition, PCAT-1 epigenetically silenced PTEN through binding to the histone methyltransferase enhancer of zeste homolog 2 (EZH2), thus increasing H3K27me3. More importantly, PTEN silencing counteracted PCAT-1 knockdown-mediated enhancement in cisplatin sensitivity of CDDP-resistant GC cells. In summary, PCAT-1 led to cisplatin resistance in GC cells through epigenetically suppressing PTEN expression, providing a novel therapeutic strategy for GC patients with chemoresistance.

Six2 promotes non-small cell lung cancer cell stemness via transcriptionally and epigenetically regulating E-cadherin

OBJECTIVES

The roles and related mechanisms of six2 in regulating non-small cell lung cancer (NSCLC) cells progression are unclear. This work aimed to explore the roles of six2 in NSCLC cell stemness.

MATERIALS AND METHODS

Kaplan-Meier plotter analysis was used to examine the correlation between six2 expression and the survival of NSCLC patients. Quantitative reverse transcription PCR and Western blot were performed to detect six2 expression in clinical samples. Moreover, transwell migration, tumour spheroid formation and in vivo tumour formation assays were used to examine the effects of six2 on NSCLC cell progression. Additionally, methylation analysis was carried out to measure E-cadherin methylation level in different cells. Finally, cell viability assay was performed to explore the effects of six2 on chemotherapeutic sensitivity of NSCLC cells.

RESULTS

Lung cancer patients with a higher six2 expression level displayed a shorter overall survival. Six2 expression was higher in lung cancer tissues than in normal adjacent tissues. Additionally, six2 knockdown suppressed NSCLC cell stemness. Mechanistically, six2 overexpression inhibited epithelial marker E-cadherin expression via stimulating its promoter methylation. And E-cadherin knockdown rescued six2 knockdown-induced decrease of NSCLC cancer cell stemness. Notably, six2 knockdown enhanced cisplatin sensitivity in parental NSCLC cells and attenuated cisplatin resistance in cisplatin-resistant NSCLC cells.

CONCLUSIONS

Our results suggest that six2 facilitates NSCLC cell stemness and attenuates chemotherapeutic sensitivity via suppressing E-cadherin expression.

WITHDRAWN: Tanshinone IIA-mediated inhibition on miR-125b/STARD13 axis attenuates the stemness and enhances adriamycin sensitivity of breast cancer cells

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Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit Is Required for Uterine Epithelial Integrity

Normal proliferation and differentiation of uterine epithelial cells are critical for uterine development and function. Enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), a core component of polycomb repressive complexes 2, possesses histone methyltransferase activity that catalyzes the trimethylation of lysine 27 of histone H3. EZH2 has been involved in epithelial-mesenchymal transition, a key event in development and carcinogenesis. However, its role in uterine epithelial cell function remains unknown. To determine the role of uterine EZH2, Ezh2 was conditionally deleted using progesterone receptor Cre recombinase, which is expressed in both epithelial and mesenchymal compartments of the uterus. Loss of EZH2 promoted stratification of uterine epithelium, an uncommon and detrimental event in the uterus. The abnormal epithelium expressed basal cell markers, including tumor protein 63, cytokeratin 5 (KRT5), KRT6A, and KRT14. These results suggest that EZH2 serves as a guardian of uterine epithelial integrity, partially via inhibiting the differentiation of basal-like cells and preventing epithelial stratification. The observed epithelial abnormality was accompanied by fertility defects, altered uterine growth and function, and the development of endometrial hyperplasia. Thus, the Ezh2 conditional knockout mouse model may be useful to explore mechanisms that regulate endometrial homeostasis and uterine function.

lncRNA B4GALT1-AS1 promotes colon cancer cell stemness and migration by recruiting YAP to the nucleus and enhancing YAP transcriptional activity

Here, an RNA-sequencing assay revealed long noncoding RNAs (lncRNAs) with an ectopic expression between colon cancer (CC) and normal colon epithelial cells, in which lncRNA B4GALT1-AS1 exhibited the highest change. A 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay indicated that B4GALT1-AS1 knockdown had no effect on CC cell viability, however, cell clone formation analysis showed that B4GALT1-AS1 knockdown attenuated the capacity of cell clone formation. Additionally, gene set enrichment analysis of this data set revealed that positive enrichment of stem cell-differentiated signatures and negative embryonic stem cell function and adult tissue stem module were observed in CC cells with B4GALT1-AS1 knockdown. Furthermore, B4GALT1-AS1 knockdown suppressed the stemness-marker expression, the ability of cell spheroid formation, and ALDH1 activity in CC cells. Mechanistically, RNA-sequencing data found that the Hippo pathway in cancer was shown on pathways mostly upregulated by B4GALT1-AS1 knockdown, and B4GALT1-AS1 directly bound to the yes-associated protein (YAP), a downstream executor of the Hippo pathway, and B4GALT1-AS1 knockdown promoted the nuclear cytoplasm translocation of YAP and decreased YAP transcriptional activity. Notably, YAP overexpression attenuated the inhibitory effects mediated by B4GALT1-AS1 knockdown. Our results identify the direct binding of lncRNA B4GALT1-AS1 to YAP, which is responsible for CC cell stemness.

Lnc-PDZD7 contributes to stemness properties and chemosensitivity in hepatocellular carcinoma through EZH2-mediated ATOH8 transcriptional repression

Background

Hepatocellular carcinoma (HCC) with stemness features are pivotal for tumorigenesis, chemoresistance, and progression. Long non-coding RNAs have been implicated in the regulation of HCC stemness features; however, their mechanisms remain largely unknown. Here, we found that Lnc-PDZD7 is a potential oncogene. We systematically analyzed the clinical significance and mechanism of Lnc-PDZD7 in stemness and chemosensitivity regulation.

Methods

We analyzed the Lnc-PDZD7 expression levels in liver cancer tissues and cell line by qRT-PCR and In situ hybridization. Gain- and loss-of-function experiments were conducted to investigate the biological functions of Lnc-PDZD7 in stemness and chemosensitivity regulation. Bioinformatics analysis, dual-luciferase reporter assays were performed to validate that Lnc-PDZD7 competitively regulates EZH2, Moreover, chromatin immunoprecipitation assays, bisulfite genomic sequencing and Western blot were performed to evaluate the mechanisms of EZH2 repressing ATOH8.

Results

Lnc-PDZD7 is frequently upregulated in HCC tissues. Patients with high Lnc-PDZD7 expression had poorer prognoses and a poor response to adjuvant TACE therapy. Lnc-PDZD7 could promote stemness features and suppress the sensitivity of HCC cells to anticancer drugs in vitro and in vivo. Mechanistically, Lnc-PDZD7 functioned as a molecular sponge for miR-101, antagonizing its ability to repress EZH2 expression. Subsequently, EZH2 can further inhibit the expression of the stemness regulator ATOH8 via elevating its H3K27 trimethylation and DNA methylation.

Conclusion

Lnc-PDZD7 promotes stemness properties and suppresses chemosensitivity though the miR-101/EZH2/ATOH8 pathway, providing new biomarkers for diagnosis and potential drug targets for HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1106-2) contains supplementary material, which is available to authorized users.

Inhibition of Smurf2 translation by miR-322/503 protects from ischemia-reperfusion injury by modulating EZH2/Akt/GSK3β signaling

Myocardial ischemia-reperfusion (I/R) is a common and lethal disease that threatens people's life worldwide. The underlying mechanisms are under intensive study and yet remain unclear. Here, we explored the function of miR-322/503 in myocardial I/R injury. We used isolated rat perfused heart as an in vivo model and H9c2 cells subjected with the oxygen and glucose deprivation followed by reperfusion as in vitro model to study myocardial I/R injury. 2,3,5-Triphenyltetrazolium chloride (TTC) staining was used to measure the infarct size, and terminal deoxynucleotidyl transferase dUTP-mediated nick-end label (TUNEL) staining was used to examine apoptosis. Quantitative RT-PCR and Western blot were used to determine expression levels of miR-322/503, Smad ubiquitin regulatory factor 2 (Smurf2), enhancer of zeste homolog 2 (EZH2), p-Akt, and p-GSK3β. Overexpression of miR-322/503 decreased infarct size, inhibited cell apoptosis, and promoted cell proliferation through upregualtion of p-Akt and p-GSK3β. Thus the expression of miR-322/503 was reduced during I/R process. On the molecular level, miR-322/503 directly bound Smurf2 mRNA and suppressed its translation. Smurf2 ubiquitinated EZH2 and degraded EZH2, which could activate Akt/GSK3β signaling. Our study demonstrates that miR-322/503 plays a beneficial role in myocardial I/R injury. By inhibition of Smurf2 translation, miR-322/503 induces EZH2 expression and activates Akt/GSK3β pathway, thereby protecting cells from ischemia reperfusion injury.

EZH2-mediated epigenetic suppression of EphB3 inhibits gastric cancer proliferation and metastasis by affecting E-cadherin and vimentin expression

EphB3 is a member of the EPH family of receptors and has been found to play a role in the carcinogenesis of some human cancers. However, its expression and clinical significance in gastric cancer (GC) have not been well documented. In the present study, we detected the expression of EphB3 in GC and adjacent noncancerous tissues and explored its relationships with the clinicopathological features and prognosis of GC patients. It was found that EphB3 silenced GC cells epigenetically by direct transcriptional repression of GC cells via polycomb group protein EZH2 mediation. EphB3 was downregulated in GC cells and tissues, and EphB3 depletion promoted GC cell growth and invasion, while ectopic overexpression of EphB3 produced a significant anti-tumor effect. EphB3 was found to be involved in epithelial-mesenchymal transition by regulating E-cadherin and vimentin expression. In addition, patients with reduced EphB3 expression had shorter disease-free survival (DFS), indicating that EphB3 may prove to be a biomarker for prognosis of GC. These results demonstrated that EphB3 functioned as a tumor-suppressor and prognostic biomarker in GC.

Long noncoding RNA HOTAIRM1 inhibits cell progression by regulating miR-17-5p/ PTEN axis in gastric cancer

OBJECTIVES

This study was conducted to identify the significantly altered long noncoding RNAs (lncRNAs), messenger RNA (mRNA) and pathways in gastric cancer (GC).

METHODS

We used microarray analysis to identify differentially expressed lncRNAs and mRNAs, whereas the obviously changed pathways were found by gene set enrichment analysis. The coexpression network of lncRNA and mRNA was constructed by Cytoscape, and their target relationships with miRNAs were predicted by miRcode and TargetScan. qRT-PCR and Western blot were performed to determine the expression levels of mRNAs and proteins in tissues and cell lines. Dual-luciferase reporter assay was applied to achieve the determination of the specific target relationships. Cell viability, migration, and apoptosis were detected by MTT assay, wound healing assay and flow cytometry, respectively. Through the xenograft assay, the gastric tumor was implanted into nude mice to investigate the influence of HOTAIRM1 in vivo.

RESULTS

HOTAIRM1 and phosphatase and tensin homolog (PTEN) were both downregulated in GC, whereas miR-17-5p was upregulated. Moreover, the PI3K/AKT pathway was found activated in GC. HOTAIRM1 targeted miR-17-5p, whereas PTEN was the downstream target gene of miR-17-5p. HOTAIRM1 suppressed proliferation and migration of GC cell line and induced their apoptosis, whereas miR-17-5p played the opposite role on GC cell line. HOTAIRM1 also postponed tumor growth in vivo and inhibited the PI3K/AKT pathway in GC.

CONCLUSIONS

LncRNA HORAIRM1 suppressed the PI3K/AKT pathway in GC and inhibited the progression of GC by serving as a competing endogenous RNA of miR-17-5p, mediating the expression of PTEN.

Overexpression of CLC-3 is regulated by XRCC5 and is a poor prognostic biomarker for gastric cancer

Background

Recently, many potential prognostic biomarkers for gastric cancer (GC) have been identified, but the prognosis of advanced GC patients remains poor. Chloride channels are promising cancer biomarkers, and their family member chloride channel-3 (CLC-3) is involved in multiple biological behaviors. However, whether CLC-3 is a prognostic biomarker for GC patients is rarely reported. The molecular mechanisms by which CLC-3 is regulated in GC are unclear.

Methods

The expression of CLC-3 and XRCC5 in human specimens was analyzed using immunohistochemistry. The primary biological functions and pathways related to CLC-3 were enriched by RNA sequencing. A 5′-biotin-labeled DNA probe with a promoter region between − 248 and + 226 was synthesized to pull down CLC-3 promoter-binding proteins. Functional studies were detected by MTS, clone formation, wound scratch, transwell, and xenograft mice model. Mechanistic studies were investigated by streptavidin-agarose-mediated DNA pull-down, mass spectrometry, ChIP, dual-luciferase reporter assay system, Co-IP, and immunofluorescence.

Results

The results showed that CLC-3 was overexpressed in human GC tissues and that overexpression of CLC-3 was a poor prognostic biomarker for GC patients (P = 0.012). Furthermore, higher expression of CLC-3 was correlated with deeper tumor invasion (P = 0.006) and increased lymph node metastasis (P = 0.016), and knockdown of CLC-3 inhibited cell proliferation and migration in vitro. In addition, X-ray repair cross-complementing 5 (XRCC5) was identified as a CLC-3 promoter-binding protein, and both CLC-3 (HR 1.671; 95% CI 1.012–2.758; P = 0.045) and XRCC5 (HR 1.795; 95% CI 1.076–2.994; P = 0.025) were prognostic factors of overall survival in GC patients. The in vitro and in vivo results showed that the expression and function of CLC-3 were inhibited after XRCC5 knockdown, and the inhibition effects were rescued by CLC-3 overexpression. Meanwhile, the expression and function of CLC-3 were promoted after XRCC5 overexpression, and the promotion effects were reversed by the CLC-3 knockdown. The mechanistic study revealed that knockdown of XRCC5 suppressed the binding of XRCC5 to the CLC-3 promoter and subsequent promoter activity, thus regulating CLC-3 expression at the transcriptional level by interacting with PARP1.

Conclusions

Our findings indicate that overexpression of CLC-3 is regulated by XRCC5 and is a poor prognostic biomarker for gastric cancer. Double targeting CLC-3 and XRCC5 may provide the promising therapeutic potential for GC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0660-y) contains supplementary material, which is available to authorized users.

Epigenetic Contribution of High-Mobility Group A Proteins to Stem Cell Properties

High-mobility group A (HMGA) proteins have been examined to understand their participation as structural epigenetic chromatin factors that confer stem-like properties to embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and cancer stem cells (CSCs). The function of HMGA was evaluated in conjunction with that of other epigenetic factors such as histones and microRNAs (miRs), taking into consideration the posttranscriptional modifications (PTMs) of histones (acetylation and methylation) and DNA methylation. HMGA proteins were coordinated or associated with histone and DNA modification and the expression of the factors related to pluripotency. CSCs showed remarkable differences compared with ESCs and iPSCs.