Glioblastoma (GBM) is a prevalent and highly lethal form of glioma, with rapid tumor progression and frequent recurrence. Excessive outgrowth of pericytes in GBM governs the ecology of the perivascular niche, but their function in mediating chemoresistance has not been fully explored. Herein, we uncovered that pericytes potentiate DNA damage repair (DDR) in GBM cells residing in the perivascular niche, which induces temozolomide (TMZ) chemoresistance. We found that increased pericyte proportion correlates with accelerated tumor recurrence and worse prognosis. Genetic depletion of pericytes in GBM xenografts enhances TMZ-induced cytotoxicity and prolongs survival of tumor-bearing mice. Mechanistically, C-C motif chemokine ligand 5 (CCL5) secreted by pericytes activates C-C motif chemokine receptor 5 (CCR5) on GBM cells to enable DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-mediated DDR upon TMZ treatment. Disrupting CCL5-CCR5 paracrine signaling through the brain-penetrable CCR5 antagonist maraviroc (MVC) potently inhibits pericyte-promoted DDR and effectively improves the chemotherapeutic efficacy of TMZ. GBM patient-derived xenografts with high CCL5 expression benefit from combined treatment with TMZ and MVC. Our study reveals the role of pericytes as an extrinsic stimulator potentiating DDR signaling in GBM cells and suggests that targeting CCL5-CCR5 signaling could be an effective therapeutic strategy to improve chemotherapeutic efficacy against GBM.

Plastic phenotype convention between glioma stem cells (GSCs) and non-stem tumor cells (NSTCs) significantly fuels glioblastoma heterogeneity that causes therapeutic failure. Recent progressions indicate that glucose metabolic reprogramming could drive cell fates. However, the metabolic pattern of GSCs and NSTCs and its association with tumor cell phenotypes remain largely unknown. Here we found that GSCs were more glycolytic than NSTCs, and voltage-dependent anion channel 2 (VDAC2), a mitochondrial membrane protein, was critical for metabolic switching between GSCs and NSTCs to affect their phenotypes. VDAC2 was highly expressed in NSTCs relative to GSCs and coupled a glycolytic rate-limiting enzyme platelet-type of phosphofructokinase (PFKP) on mitochondrion to inhibit PFKP-mediated glycolysis required for GSC maintenance. Disruption of VDAC2 induced dedifferentiation of NSTCs to acquire GSC features, including the enhanced self-renewal, preferential expression of GSC markers, and increased tumorigenicity. Inversely, enforced expression ofVDAC2 impaired the self-renewal and highly tumorigenic properties of GSCs. PFK inhibitor clotrimazole compromised the effect of VDAC2 disruption on glycolytic reprogramming and GSC phenotypic transition. Clinically, VDAC2 expression inversely correlated with glioma grades (Immunohistochemical staining scores of VDAC2 were 4.7 ± 2.8, 3.2 ± 1.9, and 1.9 ± 1.9 for grade II, grade III, and IV, respectively, p < 0.05 for all) and the patients with high expression of VDAC2 had longer overall survival than those with low expression of VDAC2 (p = 0.0008). In conclusion, we demonstrate that VDAC2 is a new glycolytic regulator controlling the phenotype transition between glioma stem cells and non-stem cells and may serves as a new prognostic indicator and a potential therapeutic target for glioma patients.

Background Basal-like breast cancer (BLBC) is the most aggressive subtype of breast cancer (BC) and links to poor outcomes. As the molecular mechanism of BLBC has not yet been completely discovered, identification of key pathways and hub genes of this disease is an important way for providing new insights into exploring the mechanisms of BLBC initiation and progression. Objective The aim of this study was to identify potential gene signatures of the development and progression of the BLBC via bioinformatics analysis. Methods and results The differential expressed genes (DEGs) including 40 up-regulated and 21 down-regulated DEGs were identified between GSE25066 and GSE21422 microarrays, and these DEGs were significantly enriched in the terms related to oncogenic or suppressive roles in BLBC progression. In addition, KEGG pathway and GSEA (Gene Set Enrichment Analysis) enrichment analyses were performed for DEGs between the basal type and non-basal-type breast cancer from GSE25066 microarray. These DEGs were enriched in pathways such as cell cycle, cytokine-cytokine receptor interaction, chemokine signaling pathway, central carbon metabolism signaling and TNF signaling pathway. Moreover, the protein-protein interaction (PPI) network was constructed with those 61 DEGs using the Cytoscape software, and the biological significance of putative modules was established using MCODE. The module 1 was found to be closely related with a term of mitosis regulation and enriched in cell cycle pathway, and thus confirmed the pathological characteristic of BLBC with a high mitotic index. Furthermore, prediction values of the top 10 hub genes such as CCNB2 , BUB1 , NDC80 , CENPE , KIF2C , TOP2A , MELK , TPX2 , CKS2 and KIF20A were validated using Oncomine and Kaplan-Meier plotter. Conclusion Our results suggest the intriguing possibility that the hub genes and modules in the PPI network contributed to in-depth knowledge about the molecular mechanism of BLBC, paving a way for more accurate discovery of potential treatment targets for BLBC patients.

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