Knockdown of P4HA1 inhibits neovascularization via targeting glioma stem cell-endothelial cell transdifferentiation and disrupting vascular basement membrane

// Yiqiang Zhou 1, 2 , Guishan Jin 1, 3 , Ruifang Mi 1, 3 , Junwen Zhang 1, 3 , Jin Zhang 1, 2 , Hengzhou Xu 1, 2 , Sen Cheng 1, 2 , Yunsheng Zhang 1, 2 , Wenjie Song 1, 2 , Fusheng Liu 1, 2, 3 1 Brain Tumor Research Center, Beijing Neurosurgical Institute, Beijing 100050, P.R. China 2 Department of Neurosurgery, Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing 100050, P.R. China 3 Beijing Laboratory of Biomedical Materials, Beijing 100050, P.R. China Correspondence to: Fusheng Liu, email: liufushengs@hotmail.com Keywords: glioma stem cells, neovascularization, transdifferentiation, P4HA1 Received: November 22, 2016      Accepted: February 28, 2017      Published: March 16, 2017 ABSTRACT Emerging evidence has demonstrated transdifferentiation process of glioma stem cells (GSCs) into endothelial cells (ECs) in glioma neovascularization. Herein, we focused on screening for genes that were differentially expressed in the transdifferentiation process using microarray analysis. Bioinformatics analysis revealed differential expression of the prolyl 4-hydroxylase subunit alpha-1 (P4HA1) gene. We determined that P4HA1 expression was correlated with histological grade, the level of Ki67 and microvessel density (MVD) in human glioma specimens. Knockdown of P4HA1 inhibited the proliferation, migration and tube formation of GSCs in vitro . In vivo studies revealed that the downregulation of P4HA1 inhibited intracranial tumor growth, prolonged the overall survival time of xenograft mice and suppressed the neovascularization in brain tumors. Moreover, P4HA1 regulates the expression of vascular endothelial growth factor A (VEGF-A), especially an anti-angiogenic isoform-VEGF165b. Additionally, knockdown of P4HA1 inhibited the synthesis of collagen IV, and hence disrupted the structures of vascular basement membranes (BMs) in gliomas. Our study indicates that P4HA1 plays a pivotal role in the process of GSC-EC transdifferentiation and the structural formation of vascular BMs.