Molecular Mechanism Of MiR-202-5p Promoting The Proliferation Of Colorectal Cancer Cells By Inhibiting PTEN

Background & Objective Colorectal cancer(CRC)is still one of the leading cause of cancer-associated death in modern society.The biological function of miR-202-5p to CRC development remains controversial,largely owing to the fact that miR-202-5p can be tumor-suppressive or oncogenic in different contexts.In the current study,we show that aberrant expression of miR-202-5p has been observed in majority of human CRC.Specifically,miR-202-5p is shown to be transcriptional upregulated responsive to c-Myc and functions to promote the activation of PI3K/Akt signaling pathway by suppressing PTEN directly.Importantly,we further demonstrated that silencing or enforced expression of miR-202-5p resulted in CRC cell proliferation inhibition and enhancement,respectively.Moreover,we measured that decreased PTEN level was frequently associated with elevated miR-202-5p expression in colorectal cancer tissues.We conclude that increased miR-202-5p may serves as a tumor promoter in colorectal cancer.Methods1.The expression of miR-202-5p in colorectal cancer tissues was detected by qPCR.Then,the biological function was verified,and the cell proliferation ability was detected by cell counting and clone formation experiment after transfection of miR-202-5p mimics or inhibitors.2.EdU and flow cytometry were used to identify how miR-202-5p affected cell proliferation.3.The target genes of miR-202-5p were predicted,and the combination of miR-202-5p and target genes was verified by double luciferase assay.WB was used to detect whether the regulation of miR-202-5p on target genes was positive or negative.4.The potential c-Myc binding sites in the promoter region of miR-202-5p were analyzed and confirmed by Ch IP assay.Whether miR-202-5p is regulated by c-Myc was confirmed by luciferase assay after c-Myc overexpression and knockdown respectively.5.The correlation between the expression of miR-202-5p and c-Myc,p-Akt and PTEN was statistically analyzed by using continuous immunohistochemical sections of the tissue samples from colorectal cancer patients.Results1.MiR-202-5p was highly expressed in colorectal cancer tissues and cells.2.MiR-202-5p enhanced cell proliferation and cell cycle progression.3.MiR-202-5p directly targeted PTEN and increases Akt activation.4.MiR-202-5p was transcriptionally regulated by c-Myc.5.The c-Myc-miR-202-5p-PTEN-pAkt axis played an important clinical role in colorectal cancer.ConclusionOur findings suggested that c-Myc-miR-202-5p-PTEN-pAkt axis played an important role in promoting tumorigenesis and exhibited miR-202-5p as a valuable target in CRC therapy.