LncRNA ILF3-AS1 Promotes the Progression of Colon Adenocarcinoma Cells Through the miR-619-5p/CAMK1D Axis

INTRODUCTION: Colon adenocarcinoma (COAD) is the third most common tumor of the digestive tract. Recent studies reported that lncRNA’s abnormal expression might play a vital role in the occurrence and development of COAD. METHODS: In the present study, we investigated the expression of ILF3-AS1 in COAD cell lines, human normal colon epithelial cell line, patient tumor tissues and adjacent normal tissues by real-time quantitative PCR (RT-qPCR). Small interfering RNAs (siRNAs) were transfected into COAD cells to inhibit the expression of ILF3-AS1. The effects of ILF3-AS1 on cell proliferation, migration, invasion and apoptosis were measured by CCK-8 assay, transwell migration and invasion assay, and flow cytometry apoptosis assay, respectively. The direct binding of ILF3-AS1 and miR-619-5p/CAMK1D was validated by the luciferase reporter assay. The expression of CAMK1D and epithelial-mesenchymal transformation (EMT)-related proteins was detected by Western Blot analysis. Besides, in vivo experiments were conducted to demonstrate the oncogenic role of ILF3-AS1 in COAD. RESULTS: The results showed that the expression of ILF3-AS1 was significantly higher in COAD tissue than in normal adjacent samples, and this conclusion was confirmed in the available public datasets. After ILF3-AS1 knockdown, the proliferation of COAD cell lines SW480 and HT29 was significantly inhibited. At the same time, the apoptosis was increased, and the invasion and migration abilities were decreased. After further exploring the mechanisms, we found that ILF3-AS1 serves as a competitive endogenous RNA of mir-619-5p. It can bind to mir-619-5p and reduce its expression, thus regulating the target gene CAMK1D. In addition, we found that high expression of ILF3-AS1 was significantly associated with tumor grade, tumor size, and distant metastasis in COAD samples. In vivo experiments confirmed that ILF3-AS1 promotes tumor growth in COAD models. CONCLUSION: The present study demonstrated that ILF3-AS1 plays an oncogenic role in COAD through regulating the miR-619-5p/CAMK1D axis, and inhibition of ILF3-AS1 may pave the way for COAD treatment.