Colorectal cancer (CRC) is a malignant tumor, and the overall prognosis of patients with advanced CRC is still unsatisfactory. Circular RNAs (circRNAs) vesicle-associated membrane protein-associated protein A (circVAPA) could act as an underlying biomarker in CRC. This study aimed to explore the mechanism of circVAPA in the regulation of CRC growth. CircVAPA level was measured in CRC tumor tissues. The expression levels of circVAPA, VAPA mRNA, microRNA-125a (miR-125a), and cAMP response element binding 5 (CREB5) in CRC cells were detected by RT-qPCR. Cell cycle progression, migration and invasion, extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were measured by flow cytometry, transwell assays and Seahorse XF96 Glycolysis Analyzer, severally. The levels of glucose uptake, lactate and ATP production were examined by Glucose Uptake Colorimetric Assay kit, Lactate Assay kit and ATP Colorimetric Assay kit, respectively. The interaction between miR-125a and circVAPA or CREB5 was predicted by Starbase or DIANA TOOL, and verified by the dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. CircVAPA level was up-regulated in CRC tumor tissues. Expression levels of circVAPA and CREB5 were increased, and miR-125a was decreased in CRC cells. CircVAPA knockdown repressed CRC cells cycle progression, migration, invasion and glycolysis. CircVAPA acted as a miR-125a sponge to regulate CREB5 expression. Rescue assay confirmed that miR-125a deletion or CREB5 overexpression weakened the inhibitory effect of circVAPA knockdown on CRC growth. Our studies disclosed that circVAPA knockdown suppressed CRC cells cycle progression, migration, invasion and glycolysis partly by modulating miR-125a/CREB5 axis, suggesting a potential therapeutic strategy for CRC treatment.

中文翻译：

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环状 RNA circVAPA 敲低通过调节 miR-125a/CREB5 轴抑制结直肠癌细胞生长过程

结直肠癌（CRC）是一种恶性肿瘤，晚期结直肠癌患者的总体预后仍不理想。环状 RNA (circRNA) 囊泡相关膜蛋白相关蛋白 A (circVAPA) 可作为 CRC 的潜在生物标志物。本研究旨在探讨circVAPA在调节CRC生长中的作用机制。在 CRC 肿瘤组织中测量 CircVAPA 水平。RT-qPCR检测CRC细胞中circVAPA、VAPA mRNA、microRNA-125a（miR-125a）和cAMP反应元件结合5（CREB5）的表达水平。细胞周期进程、迁移和侵袭、细胞外酸化率 (ECAR) 和耗氧率 (OCR) 分别通过流式细胞仪、transwell 分析和 Seahorse XF96 糖酵解分析仪进行测量。葡萄糖摄取水平，分别通过葡萄糖摄取比色测定试剂盒、乳酸测定试剂盒和 ATP 比色测定试剂盒检查乳酸和 ATP 的产生。Starbase 或 DIANA TOOL 预测 miR-125a 与 circVAPA 或 CREB5 之间的相互作用，并通过双荧光素酶报告基因和 RNA 免疫沉淀 (RIP) 测定进行验证。CRC 肿瘤组织中 CircVAPA 水平上调。CRC 细胞中 circVAPA 和 CREB5 的表达水平升高，miR-125a 降低。CircVAPA 敲低抑制 CRC 细胞周期进展、迁移、侵袭和糖酵解。CircVAPA 充当 miR-125a 海绵来调节 CREB5 的表达。Rescue 试验证实 miR-125a 缺失或 CREB5 过表达削弱了 circVAPA 敲低对 CRC 生长的抑制作用。