Knockdown of circAPLP2 Inhibits Progression of Colorectal Cancer by Regulating miR-485-5p/FOXK1 Axis.

Abstract

Background: Circular RNAs (circRNAs) have recently been reported to play essential roles in the progression of various cancers, including colorectal cancer (CRC). However, the roles of circRNA amyloid precursor-like protein 2 (circAPLP2) in CRC and its underlying mechanism have not been investigated. Materials and Methods: The expression levels of circAPLP2, microRNA-485-5p (miR-485-5p), and forkhead-box K1 (FOXK1) were determined by quantitative real-time polymerase chain reaction. Cell proliferation, apoptosis, migration, and invasion were assessed by methylthiazolyldiphenyl-tetrazolium bromide assay, flow cytometry, and transwell assay, respectively. Western blot assay was performed to measure the protein levels of proliferating cell nuclear antigen, Bcl-2, Bax, vimentin, E-cadherin, fibronectin, and FOXK1. The interaction between miR-485-5p and circAPLP2 or FOXK1 was predicted by starBase and verified by dual-luciferase reporter assay. A xenograft tumor model was established to confirm the functions of circAPLP2 in vivo. The lactate production was measured using lactate assay kit. Results: circAPLP2 expression was enhanced in CRC tissues and cells. circAPLP2 knockdown or miR-485-5p overexpression suppressed cell proliferation, migration, and invasion, whereas it promoted apoptosis in CRC cells, which was reversed by upregulating FOXK1. Moreover, miR-485-5p could directly bind to circAPLP2 and its downregulation reversed the suppressive effect of circAPLP2 knockdown on progression of CRC cells. In addition, FOXK1 was a downstream target of miR-485-5p. Furthermore, circAPLP2 modulated FOXK1 expression by sponging miR-485-5p in CRC cells. Besides, interference of circAPLP2 suppressed tumor growth in vivo and inhibited glycolysis in vitro by upregulating miR-485-5p and downregulating FOXK1. Conclusions: circAPLP2 knockdown inhibited CRC progression through regulating miR-485-5p/FOXK1 axis, providing a novel avenue for treatment of CRC.