Knockdown of miR-411-3p induces M2 macrophage polarization and promotes colorectal cancer progression by regulation of MMP7.

Colorectal cancer (CRC) is prone to metastasis, leading to a poor prognosis. miR-411-3p exhibits a tumor-suppressive function in CRC, but its exact mechanism is unclear. The malignant biological properties of CRC cells were detected by Carboxyfluorescein diacetate succinimidyl ester (CFSE) staining, scratch-wound and transwell assay. Levels of markers associated with macrophage polarization were evaluated by flow cytometry and ELISA kits. Bioinformatics analysis to screen whether the downstream target mRNA of miR-411-3p is matrix metalloproteinase 7 (MMP7), and Dual-Luciferase reporter assay verified the targeting relationship between the two. qRT-PCR tested miR-411-3p and MMP7 levels. MMP7 level was quantified by Western blot. Additionally, a nude mouse subcutaneous graft tumor model was constructed, Ki-67 expression was detected by immunohistochemistry, and the impact of miR-411-3p/MMP7 on the polarization of M2 macrophages was explored. miR-411-3p expression is downregulated in CRC. Knockdown of miR-411-3p elevated the amount of CFSE-positive, migrating, and invading cells, decreased apoptosis, and elevated the levels of M2 macrophage polarization markers. After overexpression of miR-411-3p, all of the above metrics were reversed in CRC cells. miR-411-3p targeted negative regulation of MMP7 expression, and MMP7 overexpression further enhanced the promotional effect of knockdown of miR-411-3p on the malignant progression of CRC and M2 macrophage polarization. Furthermore, knockdown of miR-411-3p upregulated the MMP7 level, elevated Ki-67-positive cells count, and induced M2 macrophage polarization in vivo. Knockdown of miR-411-3p upregulates MMP7 and induces M2 macrophage polarization, which in turn promotes malignant biological progression of CRC.