BACKGROUND: Circular RNAs (circRNAs) can function as sponges for microRNA (miRNA) in carcinogenesis. This study aimed to investigate the role of the circRNA of the integrin subunit alpha 5 (ITGA5) gene and microRNA-107 (miR-107) in human colorectal carcinoma (CRC) cells in vitro and tissue samples from patients with CRC and the expression of forkhead box J3 (FOXJ3) protein.

MATERIAL AND METHODS: Thirty paired CRC tissue samples and adjacent normal colon tissue samples were studied. Human CRC cell lines, including HT29, SW480, LoVo, and HIEC cells, were studied for cell proliferation using the cell counting kit-8 (CCK-8) assay. Cell migration was studied using a transwell assay, and cell apoptosis was determined using flow cytometry. The luciferase reporter assay was used to study the interactions between ITGA5 circRNA, FOXJ3, and miR-107 in human CRC cells. The expression of ITGA5 circRNA and miR-107 was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of FOXJ3 were measured by Western blot.

RESULTS: The expression of ITGA5 circRNA was significantly reduced in CRC tissues and CRC cell lines. High ITGA5 circRNA expression inhibited the proliferation and cell migration of CRC cells and promoted the apoptosis of CRC cells. The luciferase reporter assay confirmed that ITGA5 circRNA bound to miR-107, which directly targeted FOXJ3.

CONCLUSIONS: ITGA5 circRNA may act as a sponge for miR-107 to upregulate FOXJ3 expression and act as a tumor suppressor in CRC cells.

Keywords: Colorectal Neoplasms, Genes, Tumor Suppressor, RNA, Untranslated, Forkhead Transcription Factors, Integrins, RNA, Circular