Circular RNA mitochondrial translation optimization 1 correlates with less lymph node metastasis, longer disease-free survival, and higher chemotherapy sensitivity in gastric cancer.

OBJECTIVE: Circular-mitochondrial translation optimization 1 (circ-MTO1) inhibits the progression of gastric cancer by regulating the growth, apoptosis, and invasion of tumor cells. However, its clinical potential as a biomarker for gastric cancer remains to be further evaluated. This study aimed to assess circ-MTO1 expression and its correlation with clinical features and prognosis in gastric cancer patients, as well as the effect of circ-MTO1 on the sensitivity to chemotherapy in gastric cancer cells. METHODS: Circ-MTO1 in tumor and adjacent tissues of 97 gastric cancer patients undergoing resection was examined by reverse transcription-quantitative polymerase chain reaction. HGC-27 and NCI-N87 cells transfected by circ-MOT1 overexpression plasmid (OE-circ-MOT1) and negative control (OE-NC) were treated with 0-6.4 µM oxaliplatin. Relative cell viability was detected using Cell Counting Kit-8. RESULTS: Circ-MTO1 was insufficiently expressed in gastric tumor tissue (median (interquartile range): 0.403 (0.288-0.518)) compared with adjacent tissue (median (interquartile range): 1.000 (0.715-1.524)) (p < 0.001). Besides, tumor circ-MTO1 was correlated with less lymph node metastasis (p = 0.014) and low TNM stage (p = 0.039), while was not correlated with demographic features or other clinical characteristics (all p > 0.05). Furthermore, tumor circ-MTO1 high expression was independently correlated with prolonged disease-free survival (DFS) (p = 0.013, adjusted hazard ratio (95% confidential interval): 0.314 (0.126-0.782)), but was not correlated with overall survival (p > 0.05). Lastly, in gastric cancer cells, OE-circ-MTO1 apparently decreased relative cell viabilities at oxaliplatin concentrations of 0.4, 0.8, 1.6, and 3.2 µM (all p < 0.05). CONCLUSION: Circ-MTO1 correlates with less lymph node metastasis, prolonged DFS, and improved chemotherapy sensitivity in gastric cancer.