Circular RNA MTO1 intercorrelates with microRNA-630, both associate with Enneking stage and/or pathological fracture as well as prognosis in osteosarcoma patients.

Objective: Circular RNA-mitochondrial tRNA translation optimization 1 (circ-MTO1) not only involves in bioprocess of various cancers, but also regulates osteosarcoma progression by regulating microRNA-630 (miR-630). However, the clinical role of circ-MTO1 and miR-630 in osteosarcoma is still obscure. This study aimed to assess the correlation of circ-MTO1 and miR-630 with disease features and prognosis and to explore their association with each other in osteosarcoma patients.

Methods: Forty-four osteosarcoma patients who received neoadjuvant chemotherapy to surgical resection were analyzed in this retrospective study. Then, circ-MTO1 and miR-630 expressions were evaluated in tumor and adjacent non-tumor specimens by reverse transcription quantitative polymerase chain reaction.

Results: Circ-MTO1 was lower in tumor than in non-tumor tissues (p<0.001); meanwhile, its elevated tumor expression was correlated with less advanced Enneking stage (p=0.049), good neoadjuvant chemotherapy response (p=0.029), and longer disease-free survival (DFS) (p=0.047). However, no association was found between circ-MTO1 and overall survival (OS) (p=0.122). Additionally, miR-630 in tumor was higher than in non-tumor tissues (p<0.001), while its raised tumor expression was associated with pathological fracture occurrence (p=0.003), advanced Enneking stage (p=0.036), poor neoadjuvant chemotherapy response (p=0.035), and shorter DFS (p=0.011). However, no association was found between miR-630 and OS (p=0.066). In addition, tumor circ-MTO1 was negatively associated with miR-630 (r=-0.323, p=0.032).

Conclusion: Circ-MTO1 and miR-630 expressions are inter-correlated and dysregulated in osteosarcoma patients. Besides, they associate with Enneking stage and/or pathological fracture, as well as neoadjuvant treatment response and accumulating DFS in these patients.