CircN4BP2L2 promotes colorectal cancer growth and metastasis through regulation of the miR-340-5p/CXCR4 axis.

Colorectal cancer (CRC) is the third leading cause of cancer-related death worldwide. Dysregulation of circular RNAs (circRNAs) appears to be a critical factor in CRC progression. However, mechanistic studies delineating the role of circRNAs in CRC remain limited. In this study, qRT-PCR and western blot assays were used to measure the expression of genes and proteins. Migration, invasion, proliferation, and apoptosis were examined by wound-healing, transwell, CCK-8, colony formation, and flow cytometry assays, respectively. Molecular interactions were validated by a dual-luciferase report system. A xenograft animal model was established to examine in vivo tumor growth and lung metastasis. Our data indicated that circN4BP2L2 expression was increased in CRC tissues and cell lines. Notably, inhibition of circN4BP2L2 effectively inhibited proliferation, migration, and invasion of LoVo cells, and inhibited tumor growth and metastasis in vivo, whereas the forced expression of circN4BP2L2 facilitated the proliferation, migration, and invasion of HT-29 cells. Mechanistic studies revealed that circN4BP2L2 acted as a molecular sponge of miR-340-5p to competitively promote CXCR4 expression. Furthermore, inhibition of miR-340-5p reversed the anti-cancer effects of circN4BP2L2 or CXCR4 silencing. Our data indicated an oncogenic role of circN4BP2L2 in CRC via regulation of the miR-340-5p/CXCR4 axis, which may be a promising biomarker and target for CRC treatment.