Study On Chemokine CCL20 Involves In Resistance Of Myeloma Cells To Elotuzumab And Lenalidomide

Objective:Multiple myeloma(MM)is a malignant plasma cell disease that is incurable till now.Immunotherapy has received more and more attention in the field of treatment of multiple myeloma because ithas low toxicity and side effects.Elotuzumab(Elo)is the second monoclonal antibody approved for the treatment of RRMM patients in combinationwith lenalidomide and dexamethasone(E-Rd regimen),and the first one is daratumumab,a CD38 monoclonal antibody.The target of elotuzumab is the lymphocyte activating molecule family member 7(SLAMF7,also known as CS1).Although the E-Rd regimen works well,some patients would finally develop into resistant to chemotherapy,and there are very few studies on drug resistance to elotuzumab till now.The aim of this study was to explore initially the relevant factors and possible mechanisms of drug resistance both in vivo and in vitro.Methods:1.Constructed cell models which resistant to elotuzumab and lenalidomide by continuous low dose drug stimulation;2.Gene expression microarray detected different expression genes in UW,UR,UE and URE cell lines;3.RT-qPCR validated CCL20 mRNA expression of four cell lines,and detected CCL20 mRNA expression in newly diagnostic MM(NDMM)and refractory/relapsed MM(RRMM);4.Bioinformatics Analysis of CCL20 expression in NDMM and RRMM;5.ELISA detected the content of CCL20 in the plasma of MM patients;6.Recovered CCL20 level could increase drug-resistant cell lines sensitivity to immunomodulatory drugs;7.Constructed lenalidomide-resistant(UR)mouse subcutaneous xenograft model to explore if CCL20 and lenalidomide treatment had influence on tumor volume's growth.Results:1.We successfully constructed cell models of drug resistance.2.Gene expression microarray identified the mRNA expression of CCL20 was down regulated in UR,UE and URE cell lines.3.RT-qPCR confirmed CCL20 was down regulated in UR,UE and URE cell lines and RRMM patients;bioinformatics analysis found the mRNA expression of CCL20 was also down regulated in RRMM patients.4.ELISA revealed that RRMM patients had lower level of CCL20 protein in their plasma compared to NDMM.5.CCL20 could increase sensitivity of UR,UE and URE cell lines to immunomodulatory drugs.6.In the xenograft mouse model,CCL20 could increase mouse' sensitivity to lenalidomide and slow down the growth of tumor.Conclusion:In the myeloma cell lines which resistant to lenalidomide and elotuzumab as well as RRMM patients,we found the expression of CCL20 gene was decreased;RRMM patients had lower CCL20 in their plasma;furthermore we found CCL20 could increase sensitivity of drug-resistant cell lines and slow down the tumor growth of mouse which resistant to lenalidomide.