Circular RNA circMTO1 acts as an antitumor factor in rectal cancer cell lines by downregulation of miR-19b-3p.

Abstract

Rectal cancer is the frequent malignant tumor of the digestive tract. It has a strong ability to invade and metastasize, a poor clinical prognosis and a high recurrence rate. Circular RNA mitochondrial translation optimization 1 homolog (circMTO1) exerts functions of regulating tumor development. Thus, we aimed to investigate the roles and mechanisms of circMTO1 in rectal cancer. Cell activity, proliferation, migration, and incursion were tested through cell counting kit-8, bromodeoxyuridine, flow cytometry, transwell, and BioCoat Matrigel Invasion Chambers, separately. Expression of circMTO1 and other relative factors was tested through quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot. qRT-PCR revealed that circMTO1 expression was notably reduced in rectal cancer tissues. Overexpression of circMTO1 was established in SW837 and SNU-61 cells. Then we found that circMTO1 overexpression could suppress cell proliferation, migration, and incursion and induce apoptosis through downregulating miR-19b-3p. However, these trends were opposite in both cells when circMTO1 was knocked down. Besides, circMTO1 overexpression inhibited Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3) and AMP-activated protein kinase (AMPK) signal pathways via negatively regulating miR-19b-3p to play its antitumor roles. circMTO1 acted as a tumor inhibitor influencing the growth, migration, and incursion of rectal cancer cells and JAK1/STAT3 and AMPK signal pathways through downregulating miR-19b-3p.