Studies On The Anti-Tumor Activity And Mechanisms Of The Combination Of Lenalidomide And Clarithromycin Against Multiple Myeloma

Background and objective:Multiple myeloma(MM) is a malignant plasma cell disease, which is characterized by malignant proliferation of monoclonal plasma cell and large secretion of monoclonal immunoglobulin. In recent years, the application of proteasome inhibitor and immunomodulatory drugs(IMi Ds) contributes to the improved response rate of MM. IMi Ds show direct anti-tumor effects and immunomudulatory effects by disrupting myeloma cell microenvironment. Bi Rd regimin which is composed of the second generation IMi Ds lenalidomide, clarithromycin and dexamethasone manifests a good response in treatment-na?ve and relapsed/refractory MM patients. However, the mechanism is still not clear. This study was aimed to investigate the synergistic effect of lenalidomide and clarithromycin on MM cells and its possible mechanism, and to explore how clarithromycin contributes to the cell viability of lenalidomide-resistant cell line.Material and Method: Human MM cell lines(MM.1S,MM.1R) were treated with lenalidomide and clarithromycin alone or their combination at various concentrations, DMSO was added as a control group. Cell viability was determined by CCK-8 assay. MM cells were treated by lenalidomide or clarithromycin alone or their combinations and cell cycle and apoptotis analysis were conducted by flow cytometry. Cell cycle associated molecules were detected by western blot(WB). Lenalidomide-resistant cell line R10 R was treated with the lenalidomide or clarithromycin alone or their combinations and determined for cell viability by CCK-8 assay.Results:1. The combination of lenalidomide and clarithromycin show a significant anti-tumor effect in a dose dependent manner on MM cells. Moreover, lenalidomide combined with clarithromycin showed a synergistic anti-tumor effect on MM cells.2. The combination of lenalidomide and clarithromycin induced MM cell cycle arrest.3. The combination of lenalidomide and clarithromycin significantly induced apoptosis of MM cells.4. The combination of lenalidomide and clarithromycin upregulated p21 and downregulated CDK6 at protein level of MM cells.5. Lenalidomide combined with clarithromycin showed a significant anti-tumor effect in lenalidomide-resistant cell line R10 R,compared with lenalidomide or clarithromycin alone. Compared to being treated with clarithromycin alone, it tended to be that combination with lenalidomide showed an inhibition to R10 R cell line.Conclusion: Our study revealed that lenalidomide and clarithromycin exhibited a synergistic anti-MM effect, mainly through cell cycle arrest and induction of apoptosis. In addition, clarithromycin could overcome lenalidomide resistance. Our study provided experimental data and theoretical basis for the combination of lenalidomide and clarithromycin in treatment of MM.