Abstract: Objective To investigate the regulatory effects of miR-30e-5p on biological behaviors of colorectal cancer cells and the role of PTEN/CXCL12 axis in mediating these effects. Methods Bioinformatic analysis was performed to explore the differential expression of miR-30e-5p between colorectal cancer tissues and normal tissues. RT-qPCR was used to detect the differential expression of miR-30e-5p in intestinal epithelial cells and colorectal cancer cells. Bioinformatics and dual luciferase assay were used to predict and validate the targeting relationship between miR-30e-5p and PTEN. Human and murine colorectal cancer cell lines were transfected with miR-30e-5p mimics, miR-30e-5p inhibitor, miR-30e-5p mimics+LV-PTEN, or miR-30e-5p inhibitor + si-PTEN. The changes in biological behaviors of the cells were detected using plate clone formation assay, CCK-8 assay, flow cytometry, scratch healing and Transwell assays. PTEN and CXCL12 expressions in the cancer cells were detected by Western blotting. The effects of miR-30e-5p inhibitor on colorectal carcinogenesis and development were observed in nude mice. Results Bioinformatic analysis showed that miR-30e-5p expression was significantly elevated in colorectal cancer tissues compared with the adjacent tissue (P<0.01). Higher miR-30e-5p expression was detected in colorectal cancer cell lines than in intestinal epithelial cells (P<0.01). Dual luciferase assay confirmed the targeting relationship between miR-30e-5p and PTEN (P<0.05). Transfection with miR-30e-5p mimics significantly enhanced proliferation and metastasis and inhibited apoptosis of the colorectal cancer cells (P<0.05), and co-transfection with LV-PTEN obviously reversed these changes (P<0.05). MiR-30e-5p mimics significantly inhibited PTEN expression and enhanced CXCL12 expression in the cancer cells (P<0.01), and miR-30e-5p inhibitor produced the opposite effect. Transfection with miR-30e-5p inhibitor caused cell cycle arrest in the cancer cells, which was reversed by co-transfection with si-PTEN (P<0.05). In the in vivo experiments, the colorectal cancer cells transfected with miR-30e-5p inhibitor showed significantly lowered tumorigenesis. Conclusion Overexpression of miR-30e-5p promotes the malignant behaviors of colorectal cancer cells by downregulating PTEN to activate the CXCL12 axis.

Key words: colorectal cancer; miR-30e-5p; PTEN; CXCL12