Overexpression of miRNA-433-5p protects acute spinal cord injury through activating MAPK1.

OBJECTIVE: The aim of this study was to clarify the role of microRNA-433-5p (miRNA-433-5p) in influencing pathological lesions following acute spinal cord injury (SCI) by targeting mitogen-activated protein kinase 1 (MAPK1). PATIENTS AND METHODS: SCI model was successfully established in mice by performing hitting injury procedures. Serum levels of miRNA-433-5p and MAPK1 in SCI patients and mice were determined. Grip strengths of both forelimbs in SCI mice and controls were determined. Dual-Luciferase reporter gene assay was applied to verify the binding relation between miRNA-433-5p and MAPK1. After overexpression of miRNA-433-5p and MAPK1 in vivo, the grip strength changes in SCI mice were assessed. Furthermore, the protein level of inflammatory factor iNOS in 293T cells influenced by miRNA-433-5p and MAPK1 was detected by Western blot. RESULTS: MiRNA-433-5p was significantly downregulated in the serum of SCI patients and mice, whereas MAPK1 was up-regulated. Grip strengths of SCI mice were significantly lower than those of controls at different postoperative time points. However, this could be markedly reversed by the in vivo overexpression of miRNA-433-5p. Western blot indicated that the protein level of iNOS was remarkably downregulated in 293T cells overexpressing miRNA-433-5p. MAPK1 was confirmed as the target of miRNA-433-5p, whose expression level was negatively regulated by miRNA-433-5p. Importantly, MAPK1 partially reversed the protective role of miRNA-433-5p in grip strength of SCI mice and inflammatory response at post-SCI. CONCLUSIONS: Overexpression of miRNA-433-5p protects SCI-induced motor dysfunction and inflammatory response by targeting MAPK1.

miRNA-21 sensitizes gastrointestinal stromal tumors (GISTs) cells to Imatinib via targeting B-cell lymphoma 2 (Bcl-2).

OBJECTIVE: miRNA-21 (miRNA-21) has recently been recognized to tumor suppressive in various types of cancers. However, the role of miRNA-21 in gastrointestinal stromal tumors (GISTs) is still ambiguous. In this study, we investigated the regulation by miRNA-21 on the sensitivity of gastrointestinal stromal tumors (GISTs) cells to Imatinib. MATERIALS AND METHODS: We examined the expression of miRNA-21 and B-cell lymphoma 2 (Bcl-2) in GIST specimens by the real-time quantitative PCR assay (RT-qPCR). Then we explored the regulation by miRNA-21 on the Bcl-2 expression by the RT-qPCR assay, Western blotting assay and the luciferase assay in GIST-T1 cells. In addition, we examined the influence of miRNA-21 on the sensitivity to Imatinib of GIST-T1 cells with colony forming assay and apoptotic assay. RESULTS: Results indicated that miRNA-21 expression was suppressed in GIST tissues. And we identified putative miRNA-21 binding sites within the 3'-untranslated region (3'-UTR) of the human Bcl-2 gene. Transient transfection of miRNA-21 mimics into human GIST GIST-T1 cell line significantly downregulated the Bcl-2 expression in both mRNA and protein levels. Moreover, the miRNA-21 mimics transfection markedly aggravated the Imatinib-mediated growth inhibition and apoptosis induction in GIST-T1 cells. CONCLUSIONS: Our results demonstrated that miRNA-21 suppressed Bcl-2 expression in GIST cells and could function as a potent tumor suppressor in GIST. And the miRNA-21 promotion could sensitize GIST cells to Imatinib. It implies a potential role in the GIST treatment.