RhoGDIα suppresses self-renewal and tumorigenesis of glioma stem cells

TEM8 marks neovasculogenic tumor-initiating cells in triple-negative breast cancer

Enhanced neovasculogenesis, especially vasculogenic mimicry (VM), contributes to the development of triple-negative breast cancer (TNBC). Breast tumor-initiating cells (BTICs) are involved in forming VM; however, the specific VM-forming BTIC population and the regulatory mechanisms remain undefined. We find that tumor endothelial marker 8 (TEM8) is abundantly expressed in TNBC and serves as a marker for VM-forming BTICs. Mechanistically, TEM8 increases active RhoC level and induces ROCK1-mediated phosphorylation of SMAD5, in a cascade essential for promoting stemness and VM capacity of breast cancer cells. ASB10, an estrogen receptor ERα trans-activated E3 ligase, ubiquitylates TEM8 for degradation, and its deficiency in TNBC resulted in a high homeostatic level of TEM8. In this work, we identify TEM8 as a functional marker for VM-forming BTICs in TNBC, providing a target for the development of effective therapies against TNBC targeting both BTIC self-renewal and neovasculogenesis simultaneously.

Vasculogenic mimicry (VM) contributes to the development of triple-negative breast cancer. In this study, the authors show that TEM8 is expressed in VM-forming breast cancer stem cells and it promotes stemness and VM differentiation capacity through a RhoC/ROCK1/SMAD5 axis

Novel roles of VAT1 expression in the immunosuppressive action of diffuse gliomas

Standard treatment regimen of gliomas has almost reached a bottleneck in terms of survival benefit. Immunotherapy has been explored and applied in glioma treatment. Immunosuppression, as a hallmark of glioma, could be alleviated by inhibiting certain abnormally expressed biomarkers. Here, transcriptome data of 325 whole grade gliomas were collected from the CGGA database. The TCGA RNA sequencing database was used for validation. Western blot was used to verify the expression level of VAT1 on cellular level. The results showed that the expression of VAT1 was positively correlated with the grades of glioma as classified by WHO. A higher expression level of VAT1 was observed in the mesenchymal subtype of gliomas. The area under the curve suggested that the expression level of VAT1 might be a potential prognostic marker of mesenchymal subtype. In survival analysis, we found that patients with high VAT1 expression level tended to have shorter overall survival, which indicated the prognostic value of VAT1 expression. The results of gene ontology analysis showed that most biological processes of VAT1-related genes were involved in immune and inflammatory responses. The results of GSEA analysis showed a negative correlation between VAT1 expression and immune cells. We also identified that the expression of immune checkpoints increased with VAT1 expression. Therefore, the high expression level of VAT1 in patients with glioma was a potential indicator of a lower survival rate for patients with gliomas. Remarkably, VAT1 contributed to glioma-induced immunosuppression and might be a novel target in glioma immunotherapy.

A 5-Gene Stemness Score for Rapid Determination of Risk in Multiple Myeloma

Purpose

Risk stratification in patients with multiple myeloma (MM) remains a challenge. As clinicopathological characteristics have been demonstrated insufficient for exactly defining MM risk, and molecular biomarkers have become the focuses of interests. Prognostic predictions based on gene expression profiles (GEPs) have been the most accurate to this day. The purpose of our study was to construct a risk score based on stemness genes to evaluate the prognosis in MM.

Materials and Methods

Bioinformatics studies by ingenuity pathway analyses in side population (SP) and non-SP (MP) cells of MM patients were performed. Firstly, co-expression network was built to confirm hub genes associated with the top five Kyoto Encyclopedia of Genes and Genomes pathways. Functional analyses of hub genes were used to confirm the biologic functions. Next, these selective genes were utilized for construction of prognostic model, and this model was validated in independent testing sets. Finally, five stemness genes (ROCK1, GSK3B, BRAF, MAPK1 and MAPK14) were used to build a MM side population 5 (MMSP5) gene model, which was demonstrated to be forcefully prognostic compared to usual clinical prognostic parameters by multivariate cox analysis. MM patients in MMSP5 low-risk group were significantly related to better prognosis than those in high-risk group in independent testing sets.

Conclusion

Our study provided proof-of-concept that MMSP5 model can be adopted to evaluate recurrence risk and clinical outcome for MM. The MMSP5 model evaluated in different databases clearly indicated novel risk stratification for personalized anti-MM treatments.

MicroRNA-30a suppresses self-renewal and tumorigenicity of glioma stem cells by blocking the NT5E-dependent Akt signaling pathway

Over the past decade, increasing researches have demonstrated the implication of microRNAs (miRNAs or miRs) in tumorigenicity of glioma stem cells (GSCs). The regulatory functions of miRNAs in GSCs have emerged as potential therapeutic candidates for glioma treatment. Herein, we aim to investigate the role of miR-30a in the proliferation and self-renewal of GSCs and the possible mechanism in relation to ecto-5'-nucleotidase (NT5E)-dependent Akt signaling pathway. RT-qPCR and Western blot analysis were performed to determine the expression of miR-30a and NT5E in glioma tissues and cell lines. GSCs were isolated from glioma cells and identified using flow cytometry. The relationship between miR-30a and NT5E was determined by dual-luciferase reporter gene assay. Gain- and loss-of-function experiments were performed to examine the effects of miR-30a and NT5E on sphere formation, colony formation, and proliferation of GSCs in vitro, as well as orthotopic tumor growth of GSCs in nude mice. Additionally, the Akt signaling pathway was blocked with an Akt inhibitor, LY294002, to investigate its involvement in the regulatory effect of miR30a. miR-30a was poorly expressed in glioma tissues and cell lines as well as GSCs. NT5E, highly expressed in GSCs, was identified as a target of miR-30a. In addition, miR-30a upregulation or NT5E silencing could reduce GSC sphere formation, clone formation, proliferation, and orthotopic tumor growth in nude mice. Moreover, miR-30a inhibited the activation of the Akt signaling pathway by targeting NT5E, and ultimately suppressing the self-renewal and orthotopic tumor growth of GSCs. Our results demonstrate that miR-30a targets NT5E to inhibit the Akt signaling pathway, by which could suppress the self-renewal and orthotopic tumor growth of GSCs. Those findings may provide theoretical basis of miR-30a as a therapeutic target to suppress the glioma progression.

The antibiotic clofoctol suppresses glioma stem cell proliferation by activating KLF13

Gliomas account for approximately 80% of primary malignant tumors in the central nervous system. Despite aggressive therapy, the prognosis of patients remains extremely poor. Glioma stem cells (GSCs) which considered as the potential target of therapy for their crucial role in therapeutic resistance and tumor recurrence, are believed to be key factors for the disappointing outcome. Here, we took advantage of GSCs as the cell model to perform high-throughput drug screening and the old antibiotic, clofoctol, was identified as the most effective compound, showing reduction of colony-formation and induction of apoptosis of GSCs. Moreover, growth of tumors was inhibited obviously in vivo after clofoctol treatment especially in primary patient-derived xenografts (PDXs) and transgenic xenografts. The anticancer mechanisms demonstrated by analyzing related downstream genes and discovering the targeted binding protein revealed that clofoctol exhibited the inhibition of GSCs by upregulation of Kruppel-like factor 13 (KLF13), a tumor suppressor gene, through clofoctol's targeted binding protein, Upstream of N-ras (UNR). Collectively, these data demonstrated that induction of KLF13 expression suppressed growth of gliomas and provided a potential therapy for gliomas targeting GSCs. Importantly, our results also identified the RNA-binding protein UNR as a drug target.

Acidosis enhances the self-renewal and mitochondrial respiration of stem cell-like glioma cells through CYP24A1-mediated reduction of vitamin D

Acidosis is a significant feature of the tumor microenvironment in glioma, and it is closely related to multiple biological functions of cancer stem cells. Here, we found that the self-renewal ability, the mitochondrial activity and ATP production were elevated in stem cell-like glioma cells (SLCs) under acidic microenvironment, which promoted and maintained the stemness of SLCs. Under acidosis, 25-hydroxy vitamin D₃-24-hydroxylase (CYP24A1) was upregulated and catalyzed the fast degradation of 1α,25(OH)₂D₃. We further revealed that the active form of vitamin D (1α,25(OH)₂D₃) could inhibit the expression of stemness markers, attenuate acidosis-induced increase of self-renewal ability and mitochondrial respiration in stem cell-like glioma cells. Our study indicates that the acidosis–CYP24A1–vitamin D pathway may be a key regulator of the cancer stem cell phenotype in malignant glioma and point out the potential value for the utilization of vitamin D to target cancer stem cells and to restrain the growth of malignant glioma in the future.

LC-MS-based metabolomics reveals metabolic signatures related to glioma stem-like cell self-renewal and differentiation

A metabolomic study of three glioma cell lines with different stemness were conducted. The specific metabolite signatures associated with SLC self-renewal and differentiation were characterized.