ABSTRACT
BACKGROUND: Human microRNA 452 (MIR452) has been linked to both colorectal cancer (CRC) tissues and dextran sulfate sodium (DSS)-induced colitis. OBJECTIVE: We analyzed the correlation between MIR452 and its putative target gene in human CRC cells and in mouse colitis tissues. METHODS: Luciferase reporter assay confirmed that Src homologous and collagen adaptor protein 1 (SHC1) is a direct target of MIR452. Furthermore, the expression of proteins or mRNA was assessed by immunohistochemical analysis, Western blot, or quantitative RT-PCR (qRT-PCR). RESULTS: We found that MIR452 has a potential binding site at 3'-UTR of SHC1. Likewise, MIR452 or siSHC1 transfection dramatically reduced the level of cellular SHC1 in CRC cells. The expression of SHC1 was frequently downregulated in both human CRC tissues and mouse colitis tissues. In CRC cells, we demonstrated that MIR452 regulated the expression of genes involved in the SHC1-mediated KRAS-MAPK signal transduction pathways. CONCLUSION: These findings suggest a potential defense mechanism in which MIR452 regulation of the adaptor protein SHC1 maintains cellular homeostasis during carcinogenesis or chronic inflammation. Therefore, MIR452 may have therapeutic value for human early-stage CRC and colitis.
Subject(s)
Colitis , Colorectal Neoplasms , MicroRNAs , Humans , Mice , Animals , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Colitis/chemically induced , Colitis/genetics , Colitis/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Signal Transduction/genetics , Inflammation , Src Homology 2 Domain-Containing, Transforming Protein 1/genetics , Src Homology 2 Domain-Containing, Transforming Protein 1/adverse effects , Src Homology 2 Domain-Containing, Transforming Protein 1/metabolismABSTRACT
Previous studies showed that miR-124 had a protective role by reducing oxidant stress and preventing cell apoptosis and autophagy. However, its role in doxorubicin-induced cardiomyopathy was less known. In our study, we confirmed increased ROS and decreased expression of miR-124 in doxorubicin-treated heart tissues and primary cardiomyocytes. The oxidative stress and cell apoptosis were alleviated by overexpressing miR-124, characterized by decreased activity of MDA and increased activity of SOD. While inhibiting miR-124 generated opposed effects. Mechanistically, our bioinformatic prediction and luciferase assay confirmed that miR-124 inhibited the expression of p66Shc, a proapoptotic signaling pathway. Our results suggested that miR-124 was hopeful to become a therapeutic target in doxorubicin-related cardiomyopathy.
