miR-140-3p inhibits colorectal cancer progression and its liver metastasis by targeting BCL9 and BCL2

Abstract

Recent studies have identified microRNAs (miRNAs) as a compelling novel class of biomarker in colorectal cancer (CRC) development and metastasis. Here, we demonstrated that the level of plasma exosomal miR-140-3p in CRC patients was lower than that in healthy controls. The decreased miR-140-3p level was also observed in CRC patients with liver metastasis. The expression of miR-140-3p in CRC tissues were significantly lower than that in matched normal tissues. Functionally, miR-140-3p overexpression suppressed proliferation, migration, invasion, and β-catenin nuclear translocation, as well as promoted apoptosis in LoVo cells, while inhibition of miR-140-3p reversed these cellular processes in HCT 116 cells. Notably, BCL9 and BCL2 were recognized as direct targets of miR-140-3p. BCL9 knockdown abrogated miR-140-3p inhibitor-induced effects on HCT 116 cells with decreased proliferation, migration, and invasion. BCL2 knockdown increased apoptosis of miR-140-3p inhibitor-transfected HCT 116 cells. In vivo experiments revealed that miR-140-3p overexpression inhibited tumor growth in LoVo xenograft model and diminished metastatic nodules in nude mice liver. Taken together, this work supports that miR-140-3p exerts as a tumor suppressor in CRC progression via targeting BCL9 and BCL2, and suggests miR-140-3p-BCL9/BCL2 axis may be applied in miRNA-based therapy and prognostication of CRC.