Synthetic RNA Therapeutics in Cancer.

Recent advances in the RNA delivery system have facilitated the development of a separate field of RNA therapeutics, with modalities including mRNA, microRNA (miRNA), antisense oligonucleotide (ASO), small interfering RNA, and circular (circRNA) that have been incorporated into oncology research. The main advantages of the RNA-based modalities are high flexibility in designing RNA and rapid production for clinical screening. It is challenging to eliminate tumors by tackling a single target in cancer. In the era of precision medicine, RNA-based therapeutic approaches potentially constitute suitable platforms for targeting heterogeneous tumors that possess multiple sub-clonal cancer cell populations. In this review, we discussed how synthetic coding and non-coding RNAs, such as mRNA, miRNA, ASO, and circRNA, can be applied in the development of therapeutics. SIGNIFICANCE STATEMENT: With development of vaccines against coronavirus, RNA-based therapeutics have received attention. Here, the authors discuss different types of RNA-based therapeutics potentially effective against tumor that are highly heterogeneous giving rise to resistance and relapses to the conventional therapeutics. Moreover, this study summarized recent findings suggesting combination approaches of RNA therapeutics and cancer immunotherapy.

DEP-induced ZEB2 promotes nasal polyp formation via epithelial-to-mesenchymal transition.

BACKGROUND: Diesel exhaust particles (DEPs) are associated with the prevalence and exacerbation of allergic respiratory diseases, including allergic rhinitis and allergic asthma. However, DEP-induced mechanistic pathways promoting upper airway disease and their clinical implications remain unclear. OBJECTIVE: We sought to investigate the mechanisms by which DEP exposure contributes to nasal polyposis using human-derived epithelial cells and a murine nasal polyp (NP) model. METHODS: Gene set enrichment and weighted gene coexpression network analyses were performed. Cytotoxicity, epithelial-to-mesenchymal transition (EMT) markers, and nasal polyposis were assessed. Effects of DEP exposure on EMT were determined using epithelial cells from normal people or patients with chronic rhinosinusitis with or without NPs. BALB/c mice were exposed to DEP through either a nose-only exposure system or nasal instillation, with or without house dust mite, followed by zinc finger E-box-binding homeobox (ZEB)2 small hairpin RNA delivery. RESULTS: Bioinformatics analyses revealed that DEP exposure triggered EMT features in airway epithelial cells. Similarly, DEP-exposed human nasal epithelial cells exhibited EMT characteristics, which were dependent on ZEB2 expression. Human nasal epithelial cells derived from patients with chronic rhinosinusitis presented more prominent EMT features after DEP treatment, when compared with those from control subjects and patients with NPs. Coexposure to DEP and house dust mite synergistically increased the number of NPs, epithelial disruptions, and ZEB2 expression. Most importantly, ZEB2 inhibition prevented DEP-induced EMT, thereby alleviating NP formation in mice. CONCLUSIONS: Our data show that DEP facilitated NP formation, possibly via the promotion of ZEB2-induced EMT. ZEB2 may be a therapeutic target for DEP-induced epithelial damage and related airway diseases, including NPs.

Differential roles of Sirt1 in HIF-1α and HIF-2α mediated hypoxic responses.

Hypoxia-inducible factors 1α and 2α (HIF-1α and HIF-2α) determine cancer cell fate under hypoxia. Despite the similarities of their structures, HIF-1α and HIF-2α have distinct roles in cancer growth under hypoxia, that is, HIF-1α induces growth arrest whereas HIF-2α promotes cell growth. Recently, sirtuin 1 (Sirt1) was reported to fine-tune cellular responses to hypoxia by deacetylating HIF-1α and HIF-2α. Yet, the roles of Sirt1 in HIF-1α and HIF-2α functions have been controversial. We here investigated the precise roles of Sirt1 in HIF-1α and HIF-2α regulations. Immunological analyses revealed that HIF-1α K674 and HIF-2α K741 are acetylated by PCAF and CBP, respectively, but are deacetylated commonly by Sirt1. In the Gal4 reporter systems, Sirt1 was found to repress HIF-1α activity constantly in ten cancer cell-lines but to regulate HIF-2α activity cell type-dependently. Moreover, Sirt1 determined cell growth under hypoxia depending on HIF-1α and HIF-2α. Under hypoxia, Sirt1 promoted cell proliferation of HepG2, in which Sirt1 differentially regulates HIF-1α and HIF-2α. In contrast, such an effect of Sirt1 was not shown in HCT116, in which Sirt1 inactivates both HIF-1α and HIF-2α because conflicting actions of HIF-1α and HIF-2α on cell growth may be offset. Our results provide a better understanding of the roles of Sirt1 in HIF-mediated hypoxic responses and also a basic concept for developing anticancer strategy targeting Sirt1.

Protein stabilization of ITF2 by NF-κB prevents colitis-associated cancer development.

Chronic colonic inflammation is a feature of cancer and is strongly associated with tumorigenesis, but its underlying molecular mechanisms remain poorly understood. Inflammatory conditions increased ITF2 and p65 expression both ex vivo and in vivo, and ITF2 and p65 showed positive correlations. p65 overexpression stabilized ITF2 protein levels by interfering with the binding of Parkin to ITF2. More specifically, the C-terminus of p65 binds to the N-terminus of ITF2 and inhibits ubiquitination, thereby promoting ITF2 stabilization. Parkin acts as a E3 ubiquitin ligase for ITF2 ubiquitination. Intestinal epithelial-specific deletion of ITF2 facilitated nuclear translocation of p65 and thus increased colitis-associated cancer tumorigenesis, which was mediated by Azoxymethane/Dextran sulfate sodium or dextran sulfate sodium. Upregulated ITF2 expression was lost in carcinoma tissues of colitis-associated cancer patients, whereas p65 expression much more increased in both dysplastic and carcinoma regions. Therefore, these findings indicate a critical role for ITF2 in the repression of colitis-associated cancer progression and ITF2 would be an attractive target against inflammatory diseases including colitis-associated cancer.

A novel glucagon analog with an extended half-life, HM15136, normalizes glucose levels in rodent models of congenital hyperinsulinism.

Congenital hyperinsulinism (CHI) is a rare genetic condition characterized by uncontrolled insulin secretion, resulting in hypoglycemia. Although glucagon has lately been regarded as a therapeutic option for CHI, its use is severely hampered by its poor solubility and stability at physiological pH, as well as its short duration of action. To address these constraints, we developed HM15136, a novel long-acting glucagon analog composed of a glucagon analog conjugated to the Fc fragment of human immunoglobulin G4 via a polyethylene glycol linker. In this study, we established that HM15136 was more soluble than natural glucagon (≥ 150 mg/mL vs 0.03 mg/mL). Next, we confirmed that HM15136 activated glucagon receptor in vitro and induced glycogenolysis and gluconeogenesis in rat primary hepatocytes. Pharmacokinetics (PK)/Pharmacodynamics (PD) analysis of HM15136 shows that HM15136 has a markedly longer half-life (36 h vs. < 5 min) and increased bioavailability (90%) compared to native glucagon in mice. Further, HM15136 could effectively reverse acute hypoglycemia induced by insulin challenge, and multiple doses of HM15136 could sustain increased blood glucose levels in CHI rats. In conclusion, our findings indicate that HM15136 promotes sustained elevation of blood glucose, demonstrating the potential for development as a once-weekly therapy for CHI.

Growth of Monolayer and Multilayer MoS2 Films by Selection of Growth Mode: Two Pathways via Chemisorption and Physisorption of an Inorganic Molecular Precursor.

We report facile growth methods for high-quality monolayer and multilayer MoS2 films using MoOCl4 as the vapor-phase molecular Mo precursor. Compared to the conventional covalent solid-type Mo precursors, the growth pressure of MoOCl4 can be precisely controlled. This enables the selection of growth mode by adjusting growth pressure, which facilitates the control of the growth behavior as the growth termination at a monolayer or as the continuous growth to a multilayer. In addition, the use of carbon-free precursors eliminates concerns about carbon contamination in the produced MoS2 films. Systematic studies for unveiling the growth mechanism proved two growth modes, which are predominantly the physisorption and chemisorption of MoOCl4. Consequently, the thickness of MoS2 can be controlled by our method as the application demands.

Slowed progression in models of Huntington disease by adipose stem cell transplantation.

OBJECTIVE: Adipose-derived stem cells (ASCs) are readily accessible and secrete multiple growth factors. Here, we show that ASC transplantation rescues the striatal pathology of Huntington disease (HD) models. METHODS: ASCs were isolated from human subcutaneous adipose tissue. In a quinolinic acid (QA)-induced rat model of striatal degeneration, human ASCs (1 million cells) were transplanted into the ipsilateral striatal border immediately after the QA injection. In 60-day-old R6/2 mice transgenic for HD, ASCs (0.5 million cells) were transplanted into each bilateral striata. In in vitro experiments, we treated mutant huntingtin gene-transfected cerebral neurons with ASC-conditioned media. RESULTS: In the QA model, human ASCs reduced apomorphine-induced rotation behavior, lesion volume, and striatal apoptosis. In R6/2 transgenic mice, transplantation of ASCs improved Rota-Rod performance and limb clasping, increased survival, attenuated the loss of striatal neurons, and reduced the huntingtin aggregates. ASC-transplanted R6/2 mice expressed elevated levels of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) and reactive oxygen defense enzymes and showed activation of the Akt/cAMP-response element-binding proteins. ASC-conditioned media decreased the level of N-terminal fragments of mutant huntingtin and associated apoptosis, and increased PGC-1alpha expression. INTERPRETATION: Collectively, ASC transplantation slowed striatal degeneration and behavioral deterioration of HD models, possibly via secreted factors.

Loss of EGR3 is an independent risk factor for metastatic progression in prostate cancer.

Identification of pro-metastatic genomic alterations is urgently needed to help understand and prevent the fatal course of prostate cancer. Here, we found that the transcription factor EGR3, located at chromosome 8p21.3, is a critical metastasis suppressor. Aberrant deletion of EGR3 was found in up to 59.76% (deep deletions, 16.87%; shallow deletions, 42.89%) of prostate cancer patients. In informatics analysis, EGR3 loss was associated with prostate cancer progression and low survival rates. EGR3 expression inversely correlated with the expressions of epithelial-to-mesenchymal transition (EMT) and metastasis-related gene sets in prostate cancer tissues. In prostate cancer cells, EGR3 blocked the EMT process and suppressed cell migration and invasion. In a mouse model for cancer metastasis, EGR3 overexpression significantly suppressed bone metastases of PC3 and 22Rv1 prostate cancer cells. Mechanistically, EGR3 transcriptionally activated ZFP36, GADD45B, and SOCS3 genes by directly binding to their promoter regions. The EMT-inhibitory and tumor-suppressive roles of the EGR3 downstream genes were identified through in vitro and in silico analyses. Together, our results showed that EGR3 may be a biomarker to predict clinical outcomes and that it plays an important role in the metastatic progression of prostate cancer.

Tunable Optical Transition in 2H-MoS2 via Direct Electrochemical Engineering of Vacancy Defects and Surface S-C Bonds.

Although surface engineering has been regarded to be a great approach to modulate the optical and electrical properties of nanomaterials, the spontaneous covalent functionalization on semiconducting 2H-MoS2 is a notoriously difficult process, while several reactions have been performed on metallic 1T-MoS2. This limitation in functionalization is attributed to the difficulty of electron transfer from 2H-TMD to the reacting molecules due to its semiconducting property and neutral charge state. Unfortunately, this is an all too important prerequisite step toward creating chemically reactive radical species for surface functionalization reactions. Herein, an electrochemical approach was developed for facilitating direct surface functionalization of 2H-MoS2 with 4-bromobenzene diazonium tetraborate (4-BBDT). Successful functionalization was characterized using various microscopic and spectroscopic analyses. During the course of investigating the change of optical transition seen for modified 2H-MoS2 using photoluminescence measurement combined with theoretical calculations, our study uncovered that the controlling S-C bond and sulfur vacancy generation could tune the electronic structure of functionalized 2H-MoS2.

Fabrication and Comparison of Self-Organized Ag and Au Nanodots on Ti/MgO(001) Substrates.

We analyze and compare the differences in the dewetting phenomena and crystal structure between Ag(5.0 nm) and Au(5.0 nm) layers deposited on a Ti(1.0 nm) seed layer coated onto a MgO(001) substrate. The samples are deposited at room temperature and annealed at 350-450 °C for 5 h. The surfaces of both Ag/Ti and Au/Ti films exhibit a completely separated island structure, subsequently leading to the formation of a nanodot array after annealing. Based on atomic force microscopy (AFM) analysis, we conclude that the dewetting progression speed of Ag/Ti films is higher than that of Au/Ti films. Based on X-ray diffraction (XRD) results, the Ti thin film acts as a seed layer, assisting the epitaxial growth of fcc-Ag(001) nanodots on the MgO(001) substrate, whereas in the case of Au/Ti, the Au layer grows non-epitaxially on the MgO(001) substrate, which is related to the difference in the surface energies of Ag and Au. Furthermore, the optical absorbance spectra of the self-organized Ag and Au nanodots with the Ti seed layer are obtained in the visible light range and the optical properties of Ag and Au nanodots are compared.

BRAFV600E Transduction of an SV40-Immortalized Normal Human Thyroid Cell Line Induces Dedifferentiated Thyroid Carcinogenesis in a Mouse Xenograft Model.

Background: Despite active studies of the clinical importance of BRAFV600E, suitable research models to investigate the role of this mutation in the etiopathogenesis of human thyroid cancers are limited. Thus, we generated cell lines by transducing the simian virus (SV)-40 immortalized human thyroid cell line Nthy-ori 3-1 (Nthy) with lentiviral vectors expressing either BRAFWT (Nthy/WT) or BRAFV600E. Nthy/WT and Nthy/V600E cells were then xenografted into mice to evaluate the carcinogenic role of BRAFV600E. Methods: Each cell line was subcutaneously injected into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice, and a pathological analysis was performed. The effects of the mutation were further verified by using a BRAFV600E-selective inhibitor (PLX-4032, vemurafenib). The transcriptome was analyzed by RNA sequencing and compared with data from The Cancer Cell Line Encyclopedia and Gene Expression Omnibus. Results: While Nthy/WT was not tumorigenic in vivo, Nthy/V600E formed tumors reaching 2784.343 mm3 in 4 weeks, on average. A pathological analysis indicated that Nthy/V600E tumors were dedifferentiated thyroid cancer. We found metastases in the lung, liver, and relevant lymph nodes. A transcriptomic analysis revealed 5512 differentially expressed genes (DEGs) between the mutant and wild-type cell lines, and more DEGs were shared with anaplastic thyroid cancer than with papillary thyroid cancer. BRAFV600E activated the cell cycle mainly by regulating G1/S phases. PLX-4032 treatment significantly inhibited tumor growth and metastasis. Conclusions: Our data show that BRAFV600E plays a pivotal role in the carcinogenic transformation of an SV40-transfected immortalized normal human thyroid cell line. This xenograft model is expected to contribute to studies of the etiopathogenesis and treatment of highly malignant thyroid cancers.

Oxygen sensor FIH inhibits HACE1-dependent ubiquitination of Rac1 to enhance metastatic potential in breast cancer cells.

Oxygen is an indispensable element for cell survival and maintenance. Eukaryotic cells are equipped with a series of signaling pathways that cope with hypoxia. The dioxygenase factor inhibiting HIF (FIH) is an oxygen sensor that regulates the transcriptional activity of hypoxia-inducible factor (HIF) through asparaginyl hydroxylation. Given that HACE1 was detected as an FIH-interacting protein in a previous proteomics study, we tested whether the E3 ubiquitin ligase HACE1 is a substrate for FIH. FIH interacted with HACE1, in cells and in vitro, and was determined to hydroxylate HACE1 at the N191 residue within the ankyrin repeat domain. Hydroxylation disrupted the physical association between HACE1 and its representative target, Rac1. Under hypoxic conditions, HACE1 is less hydroxylated due to the inactivation of FIH, and subsequently functions to ubiquitinate the active form of Rac1, leading to the proteasomal degradation of Rac1. Since Rac1 stimulates cell movement, HACE1 inhibits cell migration and invasion in breast cancer by removing active Rac1. Such an effect of HACE1 is reinforced under hypoxia because HACE1 escapes from FIH-mediated hydroxylation. In clinical datasets, HACE1 downregulation is associated with poor outcomes in patients with breast cancer. Taken together, FIH is likely to act as an oxygen sensor that determines oxygen-dependent cancer progression.

Nuclear FGFR2 negatively regulates hypoxia-induced cell invasion in prostate cancer by interacting with HIF-1 and HIF-2.

The fibroblast growth factor receptor 2 (FGFR2) is a membrane receptor that promotes cell proliferation and differentiation. FGFR2 is also present in the nucleus, which raises a question on a new role of FGFR2 in regulating gene expression. Hypoxia-inducible factors 1 and 2 (HIF-1 and HIF-2) are nuclear proteins that transactivate many genes essential for cancer survival and metastasis under hypoxic conditions. Here, we investigated if nuclear FGFR2 modulates the HIF-driven hypoxic response. Using the TCGA database, we found that FGFR2 downregulation is associated with poor prognosis in prostate cancer. A gene-set enrichment analysis showed that metastasis- and hypoxia-related genes are associated with a low expression of FGFR2 in prostate cancer. Thus, we tested the possibility that FGFR2 negatively regulates the hypoxia-triggered metastasis of prostate cancer. FGFR2 controls migration and invasion of prostate cancer cells under hypoxia by inhibiting the HIF-driven gene expression. FGFR2 and HIF proteins co-localize and associate in the nucleus under hypoxia. FGFR2 interacts with the transactivation domain of HIF-1α and blocks the recruitment of coactivator p300, resulting in repression of HIF target genes. Based on these results, we propose a novel function of FGFR2 as a metastasis suppressor by controlling HIF-mediated hypoxic responses.

The IFN-γ-p38, ERK kinase axis exacerbates neutrophilic chronic rhinosinusitis by inducing the epithelial-to-mesenchymal transition.

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial inflammatory disease characterized by involvement of diverse types of inflammatory cells. Asian CRS patients frequently show infiltration of neutrophils and an elevated level of interferon (IFN)-γ; by contrast, western patients exhibit eosinophil infiltration and enhanced levels of Th2-related cytokines. Neutrophilia in tissues decreases sensitivity to corticosteroids, but the mechanisms underlying the progression of neutrophilic CRS are unclear. In this study, we investigated the role of IFN-γ in CRS patients with marked neutrophil infiltration. We report that the IFN-γ level is upregulated in the tissues of these patients, particularly those with non-eosinophilic nasal polyps. The level of IFN-γ was significantly correlated with markers of the epithelial-to-mesenchymal transition (EMT). We further demonstrated that IFN-γ induced the EMT via the p38 and extracellular signal-regulated kinase (ERK) pathways in a manner distinct from the hypoxia-inducible factor (HIF)-1α, SMAD, and NF-κB signaling pathways. In a murine nasal polyp (NP) model, blocking the p38 and ERK signaling pathways prevented NP formation and chemotactic cytokine secretion by neutrophils but not eosinophils. Taken together, our results suggest that IFN-γ can induce the EMT in nasal epithelial cells, and thus blocking the p38 and ERK pathways could be an effective therapeutic strategy against neutrophil-dominant CRS.

Aberrant expression of CITED2 promotes prostate cancer metastasis by activating the nucleolin-AKT pathway.

Despite many efforts to develop hormone therapy and chemotherapy, no effective strategy to suppress prostate cancer metastasis has been established because the metastasis is not well understood. We here investigate a role of CBP/p300-interacting transactivator with E/D-rich carboxy-terminal domain-2 (CITED2) in prostate cancer metastasis. CITED2 is highly expressed in metastatic prostate cancer, and its expression is correlated with poor survival. The CITED2 gene is highly activated by ETS-related gene that is overexpressed due to chromosomal translocation. CITED2 acts as a molecular chaperone to guide PRMT5 and p300 to nucleolin, thereby activating nucleolin. Informatics and experimental data suggest that the CITED2-nucleolin axis is involved in prostate cancer metastasis. This axis stimulates cell migration through the epithelial-mesenchymal transition and promotes cancer metastasis in a xenograft mouse model. Our results suggest that CITED2 plays a metastasis-promoting role in prostate cancer and thus could be a target for preventing prostate cancer metastasis.

FIH Is an Oxygen Sensor in Ovarian Cancer for G9a/GLP-Driven Epigenetic Regulation of Metastasis-Related Genes.

The prolyl hydroxylase domain-containing proteins (PHD1-3) and the asparaginyl hydroxlyase factor inhibiting HIF (FIH) are oxygen sensors for hypoxia-inducible factor-driven transcription of hypoxia-induced genes, but whether these sensors affect oxygen-dependent epigenetic regulation more broadly is not known. Here, we show that FIH exerts an additional role as an oxygen sensor in epigenetic control by the histone lysine methyltransferases G9a and GLP. FIH hydroxylated and inhibited G9a and GLP under normoxia. When the FIH reaction was limited under hypoxia, G9a and GLP were activated and repressed metastasis suppressor genes, thereby triggering cancer cell migration and peritoneal dissemination of ovarian cancer xenografts. In clinical specimens of ovarian cancer, expression of FIH and G9a were reciprocally associated with patient outcomes. We also identified mutations of FIH target motifs in G9a and GLP, which exhibited excessive H3K9 methylation and facilitated cell invasion. This study provides insight into a new function of FIH as an upstream regulator of oxygen-dependent chromatin remodeling. It also implies that the FIH-G9a/GLP pathway could be a potential target for inhibiting hypoxia-induced cancer metastasis.Significance: These findings deepen understanding of oxygen-dependent gene regulation and cancer metastasis in response to hypoxia. Cancer Res; 78(5); 1184-99. ©2017 AACR.

NDRG3 lowers the metastatic potential in prostate cancer as a feedback controller of hypoxia-inducible factors.

Expression of hypoxia-inducible factors (HIFs) and N-myc downstream-regulated gene 3 (NDRG3) are oxygen-dependently regulated by prolyl hydroxylase domain (PHD) enzymes. Little is known about the role of NDRG3 in the cellular adaptation to hypoxia, whereas the roles of HIFs are well understood. In this study, we investigated how NDRG3 affects the hypoxic response in prostate cancer cells. Compared with HIF-1α, hypoxic induction of NDRG3 was observed at a later phase. NDRG3 reduced hypoxic expression of HIF-1α by inhibiting AKT-driven translation of HIF1A mRNA. In addition, NDRG3 functionally inhibited HIF-1 by dissociating the coactivator p300 from HIF-1α. Accordingly, NDRG3 may fine-tune the HIF-1 signaling pathway to cope with long-term hypoxia. Of the diverse effects of HIF-1α on cancer progression, hypoxia-induced cell migration was investigated. In transwell chambers, NDRG3 negatively regulated the migration and invasion of prostate cancer cells under hypoxia. An informatics analysis using Gene Expression Omnibus (GEO) revealed that NDRG3 downregulation is associated with prostate cancer metastasis and high expression of HIF-1 downstream genes. In cancer tissue arrays, NDRG3 expression was lower in prostate cancer tissues with a Gleason score of 8 or greater and was inversely correlated with HIF-1α expression. Therefore, NDRG3 may have an anti-metastatic function in prostate cancer under a hypoxic microenvironment.

The E3 ligase C-CBL inhibits cancer cell migration by neddylating the proto-oncogene c-Src.

Neddylation is a cellular process that covalently conjugates substrate proteins with the small ubiquitin-like molecule NEDD8. As neddylation is required for fast turnover of proteins in proliferating cancer cells, the neddylation process is currently regarded as a potential target for cancer therapy. However, little is known about the role of neddylation in cancer invasion and metastasis. Unexpectedly, we here found that the neddylation blockade stimulates migration of lung cancer and glioblastoma cells. Mechanistically, C-CBL acts as the E3 ligase for neddylation of the proto-oncogene c-Src. After neddylation, c-Src is poly-ubiquitinated and degraded through the proteasome, which inhibits the PI3K-AKT pathway responsible for cell migration. In human lung cancer tissues, the downregulation of C-CBL was associated with c-Src/AKT, cancer metastasis, and poor survival in patients. Therefore, C-CBL is likely to play a tumor suppressive role by antagonizing a robust oncogenic signaling driven by c-Src. This study provides new insight about the role of neddylation in cancer metastasis. It also implies that the metastasis risk should be carefully evaluated before the clinical application of neddylation inhibitors as anticancer regimens.

Astrocyte-derived CCL20 reinforces HIF-1-mediated hypoxic responses in glioblastoma by stimulating the CCR6-NF-κB signaling pathway.

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-1α 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-1α in glioblastoma cells. Mechanistically, the CCL20/CCR6 signaling pathway upregulates HIF-1α 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-1α and its downstream proteins. Furthermore, CCR6 expression was correlated with HIF-1α 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.