Circular RNA BMI1 Serves as a Potential Target for Diagnosis and Treatment in Esophageal Cancer

AIMS: Previous studies have confirmed that BMI1 is elevated in esophageal cancer, which is a potential therapeutic target for esophageal cancer. However, the clinical significance of circular RNA BMI1 (circ-BMI1) in esophageal cancer is not yet clear. Herein, we revealed the clinical implication of circ-BMI1 in esophageal cancer, and provided a theoretical basis for molecular diagnosis and potential targeted therapy of esophageal cancer. METHODS: Firstly, 10 fresh paired esophageal cancer tissues and paracancer tissues, 49 esophageal cancer serum samples and 28 healthy control serum samples were involved in our study. Differential expression and clinical significance of circ-BMI1 in esophageal cancer patients and healthy controls were evaluated by quantitative Real-time RT-PCR (RT-qPCR). Secondly, effects of circ-BMI1 differential expression on biological function of esophageal cancer cell line Eca109 were analyzed. Effects of circ-BMI1 on cell proliferation, migration and colony forming ability were evaluated by CCK-8, wound healing, and colony-forming assay. Cell apoptosis, drug sensitivity tests were also be conducted. Finally, influence of Eca109 cells differentially expressed by circ-BMI1 on tumorigenicity in nude mice was studied. RESULTS: Expression of circ-BMI1 in serum and tissues of esophageal cancer patients was significantly decreased compared to controls (P < 0.001 and P = 0.003, respectively). Area under the receiver operating characteristic curve (ROC) was 0.726. Cell proliferation, migration and colony forming ability of circBMI1-Eca109 cells were obviously decreased than that of NC-Eca109 cells (P < 0.05). circBMI1-Eca109 cells were more sensitive to 5-fluorouracil and cisplatin, and tumor volume of nude mice in circBMI1-Eca109 group was smaller (P < 0.05). CONCLUSIONS: The study indicated that expression of circ-BMI1 was significantly down-regulated in esophageal cancer. Overexpression of circ-BMI1 inhibited proliferation, migration, colony formation of Eca109 cells, and tumor growth of Eca109 cells in nude mice. circ-BMI1 may be a potential target for diagnosis and treatment in esophageal cancer.