Background: As a class of endogenous noncoding RNAs, some circular RNAs (circRNAs) have recently been reported to play a role in the regulation of tumorigenesis and progression in colorectal cancer (CRC). However, the mechanisms by which most these circRNAs function in CRC are still unclear. Purpose: The objective of this study was to identify the role of circRNA-ITGA7 in CRC cell proliferation. Patients and methods: Human genome-wide circRNA microarray v2 analysis was used for expression profile analysis. Target genes were predicted using online bioinformatics database, including TargetScan, miRDB, miRTarbase and miRMap. Gene overexpression and silencing cell models were built using cell transfection. qRT-PCR and Western blot were performed for gene and protein expression assessment. CCK8, colony formation and cell cycle analysis were used for proliferation testing. Annexin V-FITC analysis was performed for apoptosis detection. Results: CircRNA sequencing analysis suggested that compared to that in adjacent normal control tissue, the expression of circ-ITGA7, a novel circRNA, is decreased significantly in CRC. Gain-of-function studies further demonstrated that circ-ITGA7 suppressed proliferation of CRC cells. Based on prediction and verification, we subsequently revealed that miR-3187-3p is a circ-ITGA7-associated miRNA. Furthermore, RNA sequencing and bioinformatics analyses showed that ASXL1-5'UTR, the target of miR-3187-3p, is upregulated in circ-ITGA7-overexpressed cells and mediates the circ-ITGA7-induced suppression of proliferation. Conclusion: Circ-ITGA7 might suppress CRC proliferation by sponging miR-3187-3p and increasing ASXL1 expression. Thus, circ-ITGA7 might be a potential diagnostic biomarker and a therapeutic target for CRC.
Keywords: ASXL1; circ-ITGA7; colorectal cancer; miR-3187-3p; proliferation.