Astrocyte‐derived CCL20 reinforces HIF‐1‐mediated hypoxic responses in glioblastoma by stimulating the CCR6‐NF‐kB signaling pathway

Abstract

During tumor development, stromal cells are co‐opted to the tumor milieu and provide favorable conditions for the tumor. Hypoxia stimulates cancer cells to acquire a more malignant phenotype via activation of hypoxia‐inducible factor 1 (HIF‐1). Given that cancer cells and astrocytes in glioblastomas coexist in a hypoxic microenvironment, we examined whether astrocytes affect the adaptation of glioblastoma cells to hypoxia. Immunoblotting, reporter assays, quantitative RT‐PCR, and chromatin immunoprecipitation were performed to evaluate HIF‐1 signaling in glioblastoma cells. Astrocyte‐derived chemokine C‐C motif ligand 20 (CCL20) was identified using cytokine arrays, and its role in glioblastoma development was evaluated in orthotopic xenografts. Astrocytes augmented HIF‐1a expression in glioblastoma cells under hypoxia. The expression of HIF‐1 downstream genes, cancer colony formation, and Matrigel invasion of glioblastoma cells were stimulated by conditioned medium from astrocytes pre‐exposed to hypoxia. CCL20 was secreted in a hypoxia‐dependent manner from astrocytes and busted the hypoxic induction of HIF‐1a in glioblastoma cells. Mechanistically, the CCL20/CCR6 signaling pathway upregulates HIF‐1a by stimulating nuclear factor kappa B‐driven transactivation of the HIF1A gene. Compared with the control tumors, CCR6‐deficient glioblastoma xenografts grew more slowly, with poor vascularization, and expressed lower levels of HIF‐1a and its downstream proteins. Furthermore, CCR6 expression was correlated with HIF‐1a expression in GEO and TCGA datasets from human glioblastoma tissues. These results suggest that glioblastoma cells adapt well to hypoxic stress by virtue of CCL20 derived from neighboring astrocytes.Support or Funding InformationThis work was supported by the National Research Foundation of Korea (2016R1A2A1A05005082). Jin received a scholarship from the BK21‐plus education program and Park JW was supported by the Education and Research Encouragement Fund of Seoul National University Hospital.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.