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The gain-of-function GLI1 transcription factor TGLI1 enhances expression of VEGF-C and TEM7 to promote glioblastoma angiogenesis.

ABSTRACT: We recently discovered that truncated glioma-associated oncogene homolog 1 (TGLI1) is highly expressed in glioblastoma (GBM) and linked to increased GBM vascularity. The mechanisms underlying TGLI1-mediated angiogenesis are unclear. In this study, we compared TGLI1- with GLI1-expressing GBM xenografts for the expression profile of 84 angiogenesis-associated genes. The results showed that expression of six genes were upregulated and five were down-regulated in TGLI1-carrying tumors compared to those with GLI1. Vascular endothelial growth factor-C (VEGF-C) and tumor endothelial marker 7 (TEM7) were selected for further investigations because of their significant correlations with high vascularity in 135 patient GBMs. TGLI1 bound to both VEGF-C and TEM7 gene promoters. Conditioned medium from TGLI1-expressing GBM cells strongly induced tubule formation of brain microvascular endothelial cells, and the induction was prevented by VEGF-C/TEM7 knockdown. Immunohistochemical analysis of 122 gliomas showed that TGLI1 expression was positively correlated with VEGF-C, TEM7 and microvessel density. Analysis of NCBI Gene Expression Omnibus datasets with 161 malignant gliomas showed an inverse relationship between tumoral VEGF-C, TEM7 or microvessel density and patient survival. Together, our findings support an important role that TGLI1 plays in GBM angiogenesis and identify VEGF-C and TEM7 as novel TGLI1 target genes of importance to GBM vascularity.

SUBMITTER: Carpenter RL

PROVIDER: S-EPMC4673189 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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The gain-of-function GLI1 transcription factor TGLI1 enhances expression of VEGF-C and TEM7 to promote glioblastoma angiogenesis.

Carpenter Richard L RL Paw Ivy I Zhu Hu H Sirkisoon Sherona S Xing Fei F Watabe Kounosuke K Debinski Waldemar W Lo Hui-Wen HW

Oncotarget 20150901 26

We recently discovered that truncated glioma-associated oncogene homolog 1 (TGLI1) is highly expressed in glioblastoma (GBM) and linked to increased GBM vascularity. The mechanisms underlying TGLI1-mediated angiogenesis are unclear. In this study, we compared TGLI1- with GLI1-expressing GBM xenografts for the expression profile of 84 angiogenesis-associated genes. The results showed that expression of six genes were upregulated and five were down-regulated in TGLI1-carrying tumors compared to th ...[more]

PMID: 26093087

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Project description:Non‑small cell lung cancer (NSCLC) accounts for over 80% of all diagnosed lung cancer cases. Lung cancer is the leading cause of cancer‑related deaths worldwide. Most NSCLC cells overexpress vascular endothelial growth factor‑A (VEGF‑A) which plays a pivotal role in tumour angiogenesis. Anti‑angiogenic therapies including VEGF‑A neutralisation have significantly improved the response rates, progression‑free survival and overall survival of patients with NSCLC. However, the median survival of these patients is shorter than 18 months, suggesting that NSCLC cells secrete VEGF‑independent angiogenic factors, which remain unknown. We aimed to explore these factors in human NSCLC cell lines, A549, Lu99 and EBC‑1 using serum‑free culture, to which only EBC‑1 cells could adapt. By mass spectrometry, we identified 1,007 proteins in the culture supernatant derived from EBC‑1 cells. Among the identified proteins, interleukin‑8 (IL‑8), macrophage migration inhibitory factor (MIF), galectin‑1, midkine (MK), IL‑18, galectin‑3, VEGF‑A, hepatoma‑derived growth factor (HDGF), osteopontin (OPN), connective tissue growth factor (CTGF) and granulin (GRN) are known to be involved in angiogenesis. Tube formation, neutralisation and RNA interference assays revealed that VEGF‑A and HDGF function as angiogenic factors in EBC‑1 cells. To confirm whether VEGF‑A and HDGF also regulate angiogenesis in the other NSCLC cell lines, we established a novel culture method. NSCLC cells were embedded in collagen gel and cultured three‑dimensionally. Tube formation, neutralisation and RNA interference assays using the three‑dimensional (3D) culture supernatant showed that VEGF‑A and HDGF were not angiogenic factors in Lu99 cells. By gene microarray in EBC‑1 and Lu99 cells, we identified 61 mRNAs expressed only in Lu99 cells. Among these mRNAs, brain‑derived neurotrophic factor (BDNF), fibroblast growth factor‑2 (FGF‑2) and FGF‑5 are known to be involved in angiogenesis. Tube formation and neutralisation assays clarified that FGF‑2 functions as an angiogenic factor in Lu99 cells. These results indicate that HDGF enhances VEGF‑dependent angiogenesis and that FGF‑2 is a VEGF‑independent angiogenic factor in human NSCLC cells.

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Dataset Information

The gain-of-function GLI1 transcription factor TGLI1 enhances expression of VEGF-C and TEM7 to promote glioblastoma angiogenesis.

Publications

The gain-of-function GLI1 transcription factor TGLI1 enhances expression of VEGF-C and TEM7 to promote glioblastoma angiogenesis.

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