RESUMO
OBJECTIVE: To investigate the mechanism of miR-155 promoting drug resistance of children B-ALL to Ara-C by regulating Wnt/ß-Catenin signaling pathway. METHODS: The expression of miR-155 in bone marrow tissue and cell line of B-ALL was detected by PCR. The chemotherapy resistant strain REH/ Ara-C was constructed by using REH cells. REH/ Ara-C cells were transfected with miR-155 inhibitor. The proliferation of REH/Ara-C cells was detected by EdU. The apoptosis of REH/ Ara-C cells was detected by flow cytometry. The drug resistance of REH/Ara-C cells were analyzed by CCK-8 method and colony formation assay. The expression of Wnt/ß-Catenin signaling pathway related proteins were determined by Western blot. MiR-155 inhibitor and Wnt activator agonist were used to transfect REH/Ara-C cells, and their effects on cell proliferation, apoptosis and drug resistance were determined. RESULTS: Compared with normal tissues and cells, the expression level of miR-155 in B-ALL bone marrow tissue/cell line was increased (P<0.05); Compared with drug sensitive B-ALL tissues/cell lines, the expression level of miR-155 in drug resistant B-ALL tissues and cell lines was increased (P<0.05); Inhibition of miR-155 expression decreased the proliferation of REH/Ara-C cells (P<0.05), promoted apoptosis (P<0.05), enhanced the cytotoxicity of Ara-C (P<0.05), and inhibited Wnt/ß-Catenin signaling pathway related protein and MDR1 gene expression (P<0.05), which could be reversed by activating Wnt expression (P<0.05). CONCLUSION: The expression of miR-155 is up-regulated in bone marrow of children with B-ALL, which may be related to the activation of Wnt/ß-Catenin signaling pathway promotes the proliferation of B-ALL cells and inhibits apoptosis, which leads to chemotherapy resistance.