LncRNA IGFL2-AS1 as a ceRNA Promotes HCT116 Cell Malignant Proliferation via the miR-433-3p/PAK4 Axis

BACKGROUND: Colorectal cancer is a common gastrointestinal malignancy worldwide. Many studies have proved that long noncoding RNA alterations participate in colorectal cancer development. This study sought to probe the regulatory mechanism of lncRNA IGF-like family member 2 antisense RNA 1 (IGFL2-AS1) in colorectal cancer cell malignant proliferation. METHODS: LncRNA IGFL2-AS1 expression in colorectal cancer and para-cancerous tissues and colorectal cancer cell lines was detected via quantitative real-time polymerase chain reaction. HCT116 cells were transfected with si-IGFL2-AS1, microRNA (miR)-433-3p inhibitor or p21 (RAC1)-activated kinase 4, PAK4 and IGFL2-AS1 overexpression vector, followed by assessment of cell proliferation and clone formation using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay and colony formation assay. The subcellular localization of lncRNA IGFL2-AS1 was predicted and testified via the nuclear/cytosol fractionation assay. The downstream miRNA of lncRNA IGFL2-AS1 and downstream target of miRNA were predicted, and their binding relationships were testified using dual-luciferase assay and RNA immunoprediction experiment. RESULTS: LncRNA IGFL2-AS1 was abundantly expressed in colorectal cancer tissues and cells. Silencing lncRNA IGFL2-AS1 discouraged HCT116 cell malignant proliferation, while lncRNA IGFL2-AS1 overexpression played an opposite role. LncRNA IGFL2-AS1 was mainly expressed in the cytoplasm of HCT116 cells. LncRNA IGFL2-AS1 bound to miR-433-3p and inhibited its expression. miR-433-3p targeted PAK4. Silencing lncRNA IGFL2-AS1 facilitated miR-433-3p to suppress PAK4 transcription. miR-433-3p inhibition or PAK4 overexpression partly reversed the inhibition of silencing lncRNA IGFL2-AS1 on HCT116 cell malignant proliferation. CONCLUSION: LncRNA IGFL2-AS1 was abundantly expressed in colorectal cancer tissues and cells, and comparatively bound to miR-433-3p to facilitate PAK4 transcription, thus promoting HCT116 cell malignant proliferation.