Mitochondrial DNA depletion promotes vasculogenic properties through mesenchymal alteration in glioblastoma

Glioblastoma, the most aggressive brain tumour with high and heterogenic vascularity, frequently courses with mtDNA depletion. However, the effects of mtDNA depletion on mesenchymal characteristics responsible for aggressiveness and vasculogenic mimicry in glioblastoma, have not been thoroughly revealed. We aimed to investigate the effects of mtDNA depletion on EMT and vasculogenic properties in glioblastoma. mtDNA depletion was induced by low-dose ethidium bromide and then its effects on EMT and related vascular changes were analyzed. Mesenchymal and endothelial markers were analyzed by qRT-PCR and flow cytometry. Vasculogenic properties were determined through the Matrigel angiogenesis assay, periodic acid-Schiff (PAS) staining and the endothelial differentiation assay. SLUG gene, a key EMT regulator, was downregulated using RNA interference to confirm the contribution of EMT in vasculogenesis. mtDNA depletion increased mesenchymal markers, subsequent vasculogenic properties and aggressive phenotype. These were reversed by downregulating SLUG. The novel linkage between mtDNA depletion and accelerated vasculogenesis after EMT was demonstrated.

胶质母细胞瘤（Glioblastoma）是恶性程度最高的脑肿瘤，兼具高异质性血管生成特性，且常伴随线粒体DNA（mtDNA）耗竭。然而，线粒体DNA耗竭对胶质母细胞瘤中与恶性侵袭性及血管生成拟态相关的间充质特性的调控机制，尚未得到充分阐明。本研究旨在探讨线粒体DNA耗竭对胶质母细胞瘤上皮间质转化（Epithelial-Mesenchymal Transition, EMT）及血管生成特性的影响。研究通过低剂量溴化乙锭诱导细胞发生mtDNA耗竭，随后分析其对EMT及相关血管改变的调控作用；采用实时定量聚合酶链反应（qRT-PCR）与流式细胞术检测间充质及内皮标志物的表达水平，通过基质胶（Matrigel）血管生成实验、过碘酸希夫（PAS）染色及内皮分化实验评估细胞的血管生成特性；为验证EMT在血管生成过程中的贡献，本研究通过RNA干扰（RNAi）下调关键EMT调控因子SLUG基因的表达。实验结果显示，mtDNA耗竭可上调间充质标志物的表达，增强细胞的血管生成特性与恶性表型，而SLUG基因下调可逆转上述效应。本研究证实了mtDNA耗竭与EMT介导的加速血管生成之间存在新型关联。