The Synergism Between Aspirin And Lenalidomide In Multiple Myeloma Cells And The Underlying Molecular Mechanisms

Objective:1. The effects of lenalidomide(LEN) and(or) aspirin(ASA) on cell proliferation, apoptosis and cycle in multiple myeloma(MM) cells were observed to explore the interaction of antimyeloma activity between ASA and LEN.2. The expressions of VEGF and wnt/β-catenin signaling pathway proteins were determined in human MM cells treated with LEN and(or) ASA to investigate the underlying mechanisms responsible for the synergism between LEN and ASA. Methods:1. The human MM cell lines MM1.S and RPMI-8226 were incubated conventionally and the cells in logarithmic phase were used to perform study.2. CCK-8 assay was used to evaluate the proliferative inhibition of MM1.S cells and RPMI-8226 cells with exposure of LEN(1 μM) plus ASA(2.5 m M) for 24 h, 48 h and 72 h.3. The apoptotic rate of MM1.S cells and RPMI-8226 cells were examined when treated with LEN alone, ASA alone and LEN plus ASA for 48 h.4. Flow cytometry was used to analyse the cell cycle of MM1.S cells and RPMI-8226 cells treated by LEN alone, ASA alone and LEN plus ASA for 48 h.5. The levels of VEGF protein of MM1.S cells and RPMI-8226 cells were examined when exposed to LEN alone, ASA alone and LEN plus ASA for 48 h.6. The levels of wnt/β-catenin signaling pathway proteins were determined in MM1.S cells and RPMI-8226 cells treated by LEN alone, ASA alone and LEN plus ASA for 72 h. Results:1. Cotreatment of LEN and ASA caused significant inhibition of cell proliferation in human MM cell lines(MM1.S and RPMI-8226) in time-dependent manner compared with LEN or ASA treatment alone. The drug interaction assay revealed that LEN and ASA synergized to exert antimyeloma activity.2. The proapoptotic rates of MM cell lines(MM1.S and RPMI-8226) were markedly higher when exposed to LEN plus ASA in comparison with LEN or ASA treatment alone for 48 h(P < 0.05).3. The higher percentage of cells in G1 phase was observed in coadministration group of LEN and ASA when compared with LEN or ASA treatment alone(P < 0.05).4. The level of VEGF protein was significantly downregulated by ASA plus LEN in comparison with exposure to ASA or LEN alone for 48 h(P < 0.05).5. In MM1.S and RPMI-8226 cells, LEN exposure for 72 h upregulated nucleus phosphorylated β-catenin and its downstream protein of cyclin D1. Whereas ASA treatment caused cytoplasm β-catenin phosphorylation, thereby decreasing the level of nucleus β-catenin and cyclin D1. Conclusions:1. Aspirin synergized to lenalidomide to exhibit antimyeloma action.2. The synergistic antimyeloma activity between ASA and LEN could be partially ascribed to inhibiting the expression of VEGF.3. ASA exerted the chemosensitive action on lenalidomide against myeloma cells via suppressing the translocation of β-catenin into the nucleus.