MiR-199a-3p Overexpression Suppressed Cell Proliferation and Sensitized Chronic Myeloid Leukaemia Cells to Imatinib by Inhibiting mTOR Signalling.

INTRODUCTION: Chronic myeloid leukaemia (CML) is a myeloproliferative neoplasm characterized by constitutive activity of the tyrosine kinase BCR-ABL1. Drug resistance remains one of the major challenges in CML therapy. MicroRNA (miR)-199a-3p plays an important role in many tumours but has rarely been investigated in CML. We aimed to analyse the role and mechanism of miR-199a-3p in regulating imatinib resistance in CML. METHODS: The expression of miR-199a-3p and mammalian target of rapamycin (mTOR) in the serum of CML patients and CML cells was examined by quantitative real-time polymerase chain reaction. The levels of apoptosis-related proteins were determined using western blot. The relative cell survival rate and cell proliferation were determined using a CCK-8 assay and a bromodeoxyuridine (BrdU) assay, respectively. Cell cycle and apoptosis were analysed using flow cytometry. Moreover, a dual-luciferase reporter assay was performed to verify the correlation between miR-199a-3p and mTOR. RESULTS: MiR-199a-3p was downregulated in the serum of CML patients and in CML cells, while mTOR was upregulated. Both miR-199a-3p overexpression and mTOR silencing inhibited CML cell proliferation, promoted CML cell apoptosis, and sensitized these cells to imatinib. mTOR silencing reversed the promoting effect of miR-199a-3p inhibition on the proliferation of CML cells and the inhibitory effects on cell apoptosis and sensitivity to imatinib. MiR-199a-3p directly targeted mTOR. CONCLUSION: MiR-199a-3p suppressed cell propagation, facilitated apoptosis of CML cells, and sensitized CML cells to imatinib by downregulating mTOR signalling.

[Effect of Norcantharidin on Hematopoietic Function in Leucopenia Model Rat Induced by Cyclophosphamide].

OBJECTIVE: To explore the effect and mechanism of norcantharidin (NCTD) on hematopoiesis function in leucopenia model rat induced by cyclophosphamide (CTX). METHODS: Leucopenia model was replicated in SD rat with cyclophosphamide(CTX) and model animal was treated with NCTD. Peripheral blood and bone marrow tissue samples were collected from the rats in each experimental group. Peripheral white blood cells (WBC) were counted and analyzed by automatic blood cell analyzer. Histopathologic changes of the biopsied bone marrow tissues were observed by histopathological techniques. The cell cycle and apoptosis rate of bone marrow cells were detected by flow cytometry. Immunohistochemical method was applied to observe the expression of apoptosis-related proteins BCL-2 and BAX in bone marrow. RESULTS: After NCTD treatment in model rats, the WBC count of peripheral blood obviously increased, the cell structure of bone tissue significantly recovered, NCTD could promote the cell proliferation and cycle changes of bone marrow cells, inhibit the bone marrow cell apoptosis and necrosis induced with CTX, up-regulate the expression of apoptosis-related protein BCL-2 and downregulated the BAX. CONCLUSION: NCTD can stimulate the bone marrow hematopoiesis and promote recovery of peripheral white blood cell level in the leukopenia model induced by CTX, and its mechanism may be related with NCTD regulating bone marrow cell cycle and with NCTD inhibiting cell apoptosis.