Liu Jia, Liu Haiying, Zeng Qingshan, Xu Pei, Liu Mingxing, Yang Ning
Department of Nutriology, The Third Affiliated Hospital of Guangzhou Medical University, 63 Duobao Road, Liwan District, Guangzhou, 510000 China.
Cancer Cell Int. 2020 May 16;20:171. doi: 10.1186/s12935-020-01256-1. eCollection 2020.
Circular RNAs (circRNAs) are a special kind of non-coding RNAs that are implicated in cancer malignant behavior, including glycolysis. However, their contributions to gastric cancer (GC) cell glycolysis are still poorly understood. In the present study, we aimed to investigate the glycolysis-related role of circ-MAT2B in GC.
Gene expression was determined by qRT-PCR analysis. Protein level was detected by Western blot. The CCK-8, colony and EdU assays were carried out to assess GC cell viability, colony formation and DNA synthesis rate. Glycolysis was determined by glucose uptake and lactate production. The positive regulatory network of circ-MAT2B/miR-515-5p/HIF-1α was identified by RNA pull-down, RIP, ChIP and luciferase reporter assays. The in vivo role of circ-MAT2B was evaluated by using xenograft tumor model.
Circ-MAT2B was notably increased in GC and could be used as a sensitive and specific indicator of GC diagnosis and prognosis. Stable knockdown of circ-MAT2B dramatically inhibited GC cell viability, colony formation, DNA synthesis, glucose uptake and lactate production in vitro, and retarded tumor growth in vivo. Mechanistically, circ-MAT2B was dominantly located in the cytoplasm and acted as a ceRNA to sponge miR-515-5p and increase HIF-1α expression. Silencing of miR-515-5p or overexpression of HIF-1α could evidently rescue the attenuated aggressive phenotype of GC cells caused by circ-MAT2B knockdown. Importantly, HIF-1α was able to directly bind to circ-MAT2B promoter and transcriptionally activate circ-MAT2B, thus forming a positive feedback loop.
Our data suggest that circ-MAT2B is a oncogenic circRNA in GC and provide a promising therapeutic target for GC patients.
环状RNA（circRNAs）是一类特殊的非编码RNA，与癌症的恶性行为有关，包括糖酵解。然而，它们对胃癌（GC）细胞糖酵解的作用仍知之甚少。在本研究中，我们旨在探讨circ-MAT2B在GC中与糖酵解相关的作用。
通过qRT-PCR分析确定基因表达。通过蛋白质印迹法检测蛋白质水平。进行CCK-8、集落和EdU试验以评估GC细胞活力、集落形成和DNA合成率。通过葡萄糖摄取和乳酸产生来确定糖酵解。通过RNA下拉、RIP、ChIP和荧光素酶报告基因试验鉴定circ-MAT2B/miR-515-5p/HIF-1α的正调控网络。通过异种移植肿瘤模型评估circ-MAT2B在体内的作用。
circ-MAT2B在GC中显著增加，可作为GC诊断和预后的敏感且特异的指标。稳定敲低circ-MAT2B可显著抑制体外GC细胞活力、集落形成、DNA合成、葡萄糖摄取和乳酸产生，并在体内抑制肿瘤生长。机制上，circ-MAT2B主要位于细胞质中，作为竞争性内源RNA（ceRNA）海绵吸附miR-515-5p并增加HIF-1α表达。沉默miR-515-5p或过表达HIF-1α可明显挽救由circ-MAT2B敲低引起的GC细胞减弱的侵袭性表型。重要的是，HIF-1α能够直接结合circ-MAT2B启动子并转录激活circ-MAT2B，从而形成正反馈环。
我们的数据表明circ-MAT2B是GC中的一种致癌circRNA，并为GC患者提供了一个有前景的治疗靶点。
