Cinobufacini Inhibits Immune Escape of Acute Myeloid Leukemia Cells Through Regulating and Controlling MYH9/USP7/c-MYC Pathway
Objective To investigate the effect of cinobufacini on immune escape of acute myeloid leukemia(AML)by regulating myosin heavy chain 9(MYH9)/ubiquitin-specific protease 7(USP7)/cellular-myelocytomatosis viral oncogene(c-MYC)pathway.Methods(1)In vivo experiment:a nude mouse xenograft tumor model was established to evaluate the effect of cinobufotalin on the growth and immune escape of AML cells in vivo.(2)In vitro experiments:human AML cell line HL-60 was treated with different concentrations of cinobufacini,cell viability was detected by cell counting kit 8(CCK-8),and HL-60 cell invasion was detected by Transwell assay.HL-60 cells were co-cultured with activated CD8+ T cells,the expression of CD25,the surface marker of CD8+ T cells,was detected by flow cytometry,the levels of cytokines[interleukin-2(IL-2)and interferon(IFN-γ)]in the co-culture supernatant were detected by enzyme-linked immunosorbent assay(ELISA).CytoTox96 non-radioactive cytotoxicity assay was used to evaluate the cytotoxicity of CD8+ T cells to HL-60 cells.The protein expressions of MYH9,USP7 and c-MYC in HL-60 cells were detected by Western Blot.The interaction between MYH9,USP7 and ubiquitination was detected by co-immunoprecipitation(Co-IP)assay.The MYH9 overexpression plasmid was tranfected to verify the mechanism of cinobufacini in AML.Results Cinobufacini treatment inhibited xerograft tumor growth in nude mice and enhanced the anti-tumor ability of CD8+ T cells.Cinobufacini treatment inhibited HL-60 cell viability and invasion in a concentration-dependent manner.Cinobufacini treatment up-regulated the expression of CD25,a surface marker of CD8+ T cells,and also up-regulated the levels of IL-2 and IFN-γ.Cinobufotalin enhanced the toxicity of CD8+ T cells to HL-60 cells.Cinobufacini inhibits the protein expressions of MYH9,USP7 and c-MYC in HL-60 cells.MYH9 promotes c-MYC deubiquitination by recruiting USP7,but cinobufacini inhibits MYH9-mediated c-MYC deubiquitination.Conclusion Cinobufacini can reduce the recruitment of c-MYC by deubiquitinating enzyme USP7 by inhibiting the expression of MYH9,and promote the ubiquitination and degradation of c-MYC,thereby inhibiting the immune escape of AML cells.
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