ELK3: A New Molecular Marker for the Diagnosis and Prognosis of Glioma

Glioma angiogenesis is boosted by ELK3 activating the HIF-1[Formula: see text]/VEGF-A signaling axis

BACKGROUND

Clinical studies have shown that first-line use of anti-angiogenetic therapy can prolong progression-free survival but little progress has been made in extending the overall survival of the patients. We explored the role of ELK3 in glioma angiogenesis to improve and design more efficacious therapies.

METHODS

A tissue microarray and immunohistochemistry analysis were used to determine the expression of ELK3 protein in 400 glioma patients. Cell proliferation, metastasis, cell cycle, and apoptosis were monitored in U87 and U251 cells using CCK-8, EdU, transwell assays, and flow cytometry. A tube-formation assay, a rat aorta ring sprouting assay, and a matrigel plug assay were performed to examine the antiangiogenic activity of ELK3. An ELISA, Western blot, and correlation analysis of the CGGA dataset were used to detect the association between ELK3 and VEGF-A or ELK3 and HIF-1[Formula: see text]. Besides, orthotopic transplantation in nude mice and histopathological and immunological analysis of in vitro tumors were used to explore the effect of ELK3 on tumor progression and median survival.

RESULTS

ELK3 was upregulated in glioma tissues and associated with a poor prognosis. In vitro, ELK3 promoted cell proliferation and cell cycle progression, induced metastasis, and suppressed apoptosis. Then, silencing ELK3 inhibited VEGF-A expression and secretion by facilitating HIF-1[Formula: see text] degradation via ubiquitination. Finally, knockdown ELK3 inhibited tumor progression and angiogenesis in vitro and in vivo, as well as prolonged nude mice's median survival.

CONCLUSIONS

Our findings first evidenced that ELK3 is crucial for glioma because it promotes angiogenesis by activating the HIF-1[Formula: see text]/VEGF-A signaling axis. Therefore, we suggest that ELK3 is a prognostic marker with a great potential for glioma angiogenesis and ELK3-targeted therapeutic strategies might hold promise in improving the efficacy of anti-angiogenic therapies.

ETS transcription factors: Multifaceted players from cancer progression to tumor immunity

The E26 transformation specific (ETS) family comprises 28 transcription factors, the majority of which are involved in tumor initiation and development. Serving as a group of functionally heterogeneous gene regulators, ETS factors possess a structurally conserved DNA-binding domain. As one of the most prominent families of transcription factors that control diverse cellular functions, ETS activation is modulated by multiple intracellular signaling pathways and post-translational modifications. Disturbances in ETS activity often lead to abnormal changes in oncogenicity, including cancer cell survival, growth, proliferation, metastasis, genetic instability, cell metabolism, and tumor immunity. This review systematically addresses the basics and advances in studying ETS factors, from their tumor relevance to clinical translational utility, with a particular focus on elucidating the role of ETS family in tumor immunity, aiming to decipher the vital role and clinical potential of regulation of ETS factors in the cancer field.

Transcription Factor ELK3 Promotes Stemness and Oxaliplatin Resistance of Glioma Cells by Regulating RNASEH2A

Oxaliplatin is a member of the platinum group that is often used to treat glioma, a common type of malignant brain tumor, though it does not come with desirable and notable effects. This study attempted to investigate how ELK3 impacts the oxaliplatin resistance of glioma cells and its molecular mechanism. Bioinformatics analysis was employed to screen mRNAs with differential expression in glioma cells and predict the possible regulator downstream. We used qRT-PCR to detect the expression of ELK3 and RNASEH2A. Dual-luciferase and ChIP assays were adopted to reassure the regulatory relationship between the two. We also evaluated cell viability and sphere formation efficiency through CCK-8 and sphere formation assay and calculated the IC50 value by using CCK-8 assay. The expression of stemness-related proteins (ALDH1 and Nanog) was assessed through western blot. Glioma cells and tissues presented a significantly high expression of ELK3, the knock-down of which would reduce the cell viability, stemness and oxaliplatin resistance dramatically. Bioinformatics analysis predicted RNASEH2A to be the downstream regulator of ELK3. RNASEH2A was remarkably upregulated in glioma tissue and cells. The results from dual luciferase assay and ChIP experiment verified the binding relationship between RNASEH2A promoter region and ELK3. Then through rescue experiments, we confirmed that overexpression of RNASEH2A could compensate for the inhibition of glioma cell progression resulting from the knock-down of ELK3. ELK3 could promote stemness and oxaliplatin resistance of glioma cells by upregulating RNASEH2A, indicating that targeting ELK3/RNASEH2A axis may be a possible solution to overcome oxaliplatin resistance of glioma cells.

ELK3-CXCL16 axis determines natural killer cell cytotoxicity via the chemotactic activity of CXCL16 in triple negative breast cancer

Triple-negative breast cancer (TNBC) is the most challenging subtype of breast cancer because of its aggressive behavior and the limited therapeutic strategies available. In the last decade, immunotherapy has become a promising treatment to prolong survival in advanced solid cancers including TNBC. However, the efficacy of immunotherapy in solid cancers remains limited because solid tumors contain few tumor-infiltrating lymphocytes. Here, we show that targeting an ETS transcription factor ELK3 (ELK3) recruits immune cells including natural killer (NK) cells into tumors via the chemotactic activity of chemokine. ELK3 depletion increases CXCL16 expression level and promotes NK cell cytotoxicity through CXCL16-mediated NK cell recruitment in TNBC. In silico analysis showed that ELK3 is negatively correlated with CXCL16 expression in breast cancer patient samples. Low expression of ELK3 and high expression of CXCL16 were associated with a better prognosis. Low expression of ELK3 and high expression of CXCL16 were associated with increased expression of NK cell-related genes. Our findings demonstrate that the ELK3-CXCL16 axis modulates NK cell recruitment to increase NK cell cytotoxicity, suggesting that targeting the ELK3 gene could be an adjuvant strategy for increasing the efficacy of immunotherapy in TNBC.

ELK3 Targeting AEG1 Promotes Migration and Invasion of Ovarian Cancer Cells under Hypoxia

Ovarian cancer (OC) is one of the most common tumors in female reproductive organs with a five-year survival rate of less than 45%. Metastasis is a crucial contributor to OC development. ETS transcription factor (ELK3), as a transcriptional factor, have been involved in multiple tumor development. However, its role in OC remains elusive. In this study, we observed high expression of ELK3 and AEG1 in human OC tissues. OVCAR-3 and SKOV3 cells were treated with hypoxia to mimic tumor microenvironment in vivo. We found that the expression of ELK3 was significantly increased in cells under hypoxia compared with normoxia. ELK3 knockdown inhibited cell migration and invasion abilities under hypoxia. Moreover, ELK3 knockdown decreased β-catenin expression and inhibited the activation of Wnt/β-catenin pathway in SKOV3 cells under hypoxia. Astrocyte-elevated gene-1 (AEG1) has been reported to promote OC progression. Our results showed that the mRNA level of AEG1 was decreased when ELK3 knockdown under hypoxia. Dural luciferase assay confirmed that ELK3 bound to gene AEG1 promoter (-2005-+15) and enhanced its transcriptional activity under hypoxia. Overexpression of AEG1 increased the migration and invasion abilities of SKOV3 cell with ELK3 knockdown. In the absence of ELK3, the activation of β-catenin was recovered by AEG1 overexpression. To sum up, we conclude that ELK3 promotes AEG1 expression by binding to its promoter. ELK3 could promote migration and invasion of OC cells by targeting AEG1, which provides a potential basis for therapeutic approaches to OC.

scAB detects multiresolution cell states with clinical significance by integrating single-cell genomics and bulk sequencing data

Although single-cell sequencing has provided a powerful tool to deconvolute cellular heterogeneity of diseases like cancer, extrapolating clinical significance or identifying clinically-relevant cells remains challenging. Here, we propose a novel computational method scAB, which integrates single-cell genomics data with clinically annotated bulk sequencing data via a knowledge- and graph-guided matrix factorization model. Once combined, scAB provides a coarse- and fine-grain multiresolution perspective of phenotype-associated cell states and prognostic signatures previously not visible by single-cell genomics. We use scAB to enhance live cancer single-cell RNA-seq data, identifying clinically-relevant previously unrecognized cancer and stromal cell subsets whose signatures show a stronger poor-survival association. The identified fine-grain cell subsets are associated with distinct cancer hallmarks and prognosis power. Furthermore, scAB demonstrates its utility as a biomarker identification tool, with the ability to predict immunotherapy, drug responses and survival when applied to melanoma single-cell RNA-seq datasets and glioma single-cell ATAC-seq datasets. Across multiple single-cell and bulk datasets from different cancer types, we also demonstrate the superior performance of scAB in generating prognosis signatures and survival predictions over existing models. Overall, scAB provides an efficient tool for prioritizing clinically-relevant cell subsets and predictive signatures, utilizing large publicly available databases to improve prognosis and treatments.

Latest updates on cellular and molecular biomarkers of gliomas

Gliomas are the most common central nervous system malignancies, compromising almost 80% of all brain tumors and is associated with significant mortality. The classification of gliomas has shifted from basic histological perspective to one that is based on molecular biomarkers. Treatment of this type of tumors consists currently of surgery, chemotherapy and radiation therapy. During the past years, there was a limited development of effective glioma diagnostics and therapeutics due to multiple factors including the presence of blood-brain barrier and the heterogeneity of this type of tumors. Currently, it is necessary to highlight the advantage of molecular diagnosis of gliomas to develop patient targeted therapies based on multiple oncogenic pathway. In this review, we will evaluate the development of cellular and molecular biomarkers for the diagnosis of gliomas and the impact of these diagnostic tools for better tailored and targeted therapies.

The Value of H2BC12 for Predicting Poor Survival Outcomes in Patients With WHO Grade II and III Gliomas

Purpose: Glioma is a common primary malignant brain tumor. Grade II (GII) gliomas are prone to develop into anaplastic grade III (GIII) gliomas, which indicate a higher malignancy and poorer survival outcome. This study aimed to satisfy the increasing demand for novel sensitive biomarkers and potential therapeutic targets in the treatment of GII and GIII gliomas.

Methods: A TCGA dataset was used to investigate the expression of H2BC12 mRNA in GII and GIII gliomas and its relation to clinical pathologic characteristics. Glioma tissues were collected to verify results from the TCGA dataset, and H2BC12 mRNA was detected by RT-qPCR. ROC analysis was employed to evaluate the classification power for GII and GIII. The significance of H2BC12 mRNA GII and GIII gliomas was also investigated. In addition, H2BC12 expression-related pathways were enriched by gene set enrichment analysis (GSEA). DNA methylation level and mutation of H2BC12 were analyzed by the UALCAN and CBioPortal databases, respectively.

Results: Based on the sample data from multiple databases and RT-qPCR, higher expression of H2BC12 mRNA was found in GII and GIII glioma tissue compared to normal tissue, which was consistent with a trend with our clinical specimen. H2BC12 mRNA had a better power in distinguishing between GII and GIII and yielded an AUC of 0.706 with a sensitivity of 76.9% and specificity of 81.8%. Meanwhile, high H2BC12 levels were associated with IDH status, 1p/19q codeletion, primary therapy outcome, and the histological type of gliomas. Moreover, the overall survival (OS), disease-specific survival (DSS), and progress-free interval (PFI) of GII glioma patients with higher levels of H2BC12 were shorter than those of patients with lower levels as well as GIII patients. In the multivariate analysis, a high H2BC12 level was an independent predictor for poor survival outcomes of gliomas. The Wnt or PI3K-AKT signaling pathways, DNA repair, cellular senescence, and DNA double-strand break repair were differentially activated in phenotypes that were positively associated with H2BC12. H2BC12 DNA methylation was high in TP53 nonmutant patients, and no H2BC12 mutation was observed in gliomas patients.

Conclusion: H2BC12 is a promising biomarker for the diagnosis and prognosis of patients with WHO grade II and III gliomas.