MicroRNAs in the etiology of colorectal cancer: pathways and clinical implications

MicroRNA-155 increases colon cancer chemoresistance to cisplatin by targeting forkhead box O3

To investigate the effect of microRNA (miR)-155 on colon cancer chemoresistance to cisplatine and its mechanism. Reverse transcription quantitative polymerase chain reaction was used to measure the levels of miR-155 and forkhead box O3 (FOXO3) in colon cancer specimens and cell lines. Overexpression of miR-155 and miR-155 inhibitor were transfected into colon cancer cell lines to investigate its role of chemoresistance to cisplatin in colon cancer. MTS assays were used to analyse cell viability in vitro. In vivo tumor formation assays were performed in C57BL/6 wild type and miR-155 knockout mice (miR-155-/-). A luciferase reporter assay was used to measure the translation of FOXO3. Additionally, the expression of FOXO3 was detected by western blot analysis. It was identified that miR-155 was markedly upregulated in colon cancer tissue and cell lines. Overexpression of miR-155 enhanced colon cancer cell chemoresistance to cisplatin in vitro and tumorigenesis in vivo. In addition, overexpression of miR-155 was associated with decreased levels of FOXO3, primarily through inhibiting the expression of FOXO3 to increase colon cancer resistanec to cisplatin. The present study demonstrated that miR-155 increased colon cancer drug resistance and decreased FOXO3 expression in vivo and in vitro. This may provide a novel method for the treatment of drug-resistant colon cancer.

[ARTICLE WITHDRAWN] MicroRNA-539 Inhibits the Epithelial-Mesenchymal Transition of Esophageal Cancer Cells by Twist-Related Protein 1-Mediated Modulation of Melanoma-Associated Antigen A4

This article has been withdrawn at the request of the publisher in December 2020.

Regulatory miRNAs in Colorectal Carcinogenesis and Metastasis

Colorectal cancer is one of the most common malignancies and is the second-leading cause of cancer-related death world-wide, which is linked to genetic mutations, epigenetic alterations, and oncogenic signaling activation. MicroRNAs, one of the categories of epigenetics, have been demonstrated significant roles in carcinogenesis and progression through regulating of oncogenic signaling pathways, stem cells, epithelial-mesenchymal transition, and metastasis. This review summarizes the roles of microRNAs in the regulating of Wnt, Ras, TGF-β, and inflammatory signaling pathways, stemness, and epithelial-mesenchymal transition, for carcinogenesis and metastasis in colorectal cancer. Improving our understanding of the mechanisms of regulatory interactions of microRNAs with signaling pathways in colorectal cancer formation and progression will aid in determining the genes responsible for colorectal cancer initiation, progression, metastasis, and recurrence and, finally, in developing personalized approaches for cancer prevention and therapy.