Wang Liyan, Li Bin, Yi Xiaoyuan, Xiao Xuhua, Zheng Qinghua, Ma Lei
Digestive Department, Affiliated Hospital of Guilin Medical College, Guilin City, Guangxi Zhuang Autonomous Region, China.
Cell Prolif. 2021 Mar;54(3):e12981. doi: 10.1111/cpr.12981. Epub 2021 Jan 17.
Circular RNAs (circRNAs) are essential participants in tumour progression. This study focused on investigating the mechanism of a novel functional circRNA in gastric cancer (GC).
Gene expression was detected by qRT-PCR or Western blot. Survival curves were generated via Kaplan-Meier method. In vitro and in vivo assays were used to investigate the impact of circ_SMAD4 on GC cell growth and tumorigenesis. Agarose gel electrophoresis assay, RNase R treatment and Sanger sequencing were utilized for confirming the circular structure of circ_SMAD4. Relationship between molecules was monitored by a series of mechanical experiments, as needed.
Circ_SMAD4 expression was potentiated in GC. Circ_SMAD4 depletion impeded GC cell growth in vitro and restrained tumorigenesis in vivo. Mechanically, nuclear circ_SMAD4 recruited TCF4 to facilitate CTNNB1 transcription, while cytoplasmic circ_SMAD4 sequestered miR-1276 to prevent the silence of CTNNB1 mRNA, leading to activation of Wnt/β-catenin pathway. Rescue experiments validated that circ_SMAD4 depended on miR-1276/TCF4-regulated CTNNB1 to elicit accelerating effects on GC cell growth.
Circ_SMAD4 facilitated GC tumorigenesis by activating CTNNB1-dependent Wnt/β-catenin pathway. Hopefully, the findings could provide new clues for improving GC prognosis and treatment.
环状RNA（circRNAs）是肿瘤进展的重要参与者。本研究聚焦于探究一种新型功能性circRNA在胃癌（GC）中的作用机制。
采用qRT-PCR或蛋白质免疫印迹法检测基因表达。通过Kaplan-Meier法绘制生存曲线。运用体外和体内实验研究circ_SMAD4对GC细胞生长和肿瘤发生的影响。利用琼脂糖凝胶电泳分析、RNase R处理和Sanger测序确认circ_SMAD4的环状结构。根据需要，通过一系列机制实验监测分子间的关系。
circ_SMAD4在GC中表达增强。circ_SMAD4缺失在体外抑制GC细胞生长，在体内抑制肿瘤发生。机制上，细胞核中的circ_SMAD4招募TCF4以促进CTNNB1转录，而细胞质中的circ_SMAD4隔离miR-1276以防止CTNNB1 mRNA沉默，导致Wnt/β-连环蛋白通路激活。挽救实验证实，circ_SMAD4依赖miR-1276/TCF4调节的CTNNB1对GC细胞生长产生促进作用。
circ_SMAD4通过激活CTNNB1依赖的Wnt/β-连环蛋白通路促进GC肿瘤发生。有望这些发现可为改善GC预后和治疗提供新线索。
