Circular RNA SMARCA5 correlates with favorable clinical tumor features and prognosis, and increases chemotherapy sensitivity in intrahepatic cholangiocarcinoma

OBJECTIVE: This present study aimed to investigate the correlation of circular RNA SMARCA5 (circ‐SMARCA5) with clinicopathological features and overall survival (OS), and the effect of circ‐SMARCA5 on cell proliferation and chemotherapy sensitivity to cisplatin/gemcitabine in intrahepatic cholangiocarcinoma (ICC). METHODS: Totally 92 primary ICC patients who underwent resection were recruited, and their tumor tissues and adjacent tissues were collected for circ‐SMARCA5 detection. The effect of circ‐SMARCA5 on cell proliferation and chemotherapy sensitivity was detected after circ‐SMARCA5 overexpression plasmid transfection into TFK‐1 and HuH‐28 ICC cells. RESULTS: Circ‐SMARCA5 expression was reduced in ICC tumor tissues compared to adjacent tissues. Tumor circ‐SMARCA5 high expression was negatively associated with Eastern Cooperative Oncology Group performance score, T stage, N stage, TNM stage, and abnormal CA199 status. Furthermore, OS was increased in patients with tumor circ‐SMARCA5 high expression compared with those with low expression, and further multivariate Cox's regression demonstrated that tumor circ‐SMARCA5 high expression was an independent predictive factor for longer OS. In TFK‐1 and HuH‐28 ICC cells, circ‐SMARCA5 upregulation decreased cell proliferation, reduced relative cell viability in cisplatin‐treated as well as gemcitabine‐treated cells, and also decreased inhibitory concentration by 50% value (IC(50)) of cisplatin and gemcitabine. CONCLUSION: The correlation of circ‐SMARCA5 with favorable clinical tumor features, survival profile, and its promoting effect on chemotherapy sensitivity implies its potential as a valuable biomarker in monitoring disease progression and prognosis of ICC.