BTK信号途径及BTK抑制剂在B-NHLs中的研究较为成熟并成功运用于临床，但在MM中的研究相对滞后。已有研究显示MM BTK过表达能导致干细胞相关基因和AKT/WNT/b-catenin上调，诱导MM细胞耐药。本课题从探讨BTK和来那度胺耐药相关性入手，前期证实BTK高表达能诱导MM细胞对来那度胺耐药，对BTK沉默的MM细胞行基因表达谱分析提示KPNA2是下调最为显著的基因之一，特别是BTK过表达和沉默能上调和下调KPNA2及其效应分子IRF4和c-MYC的表达。NCBI GEO DataSets分析显示KPNA2为MM患者的高表达基因，是影响PFS和OS的预后不良因素。据此我们推测BTK-KPNA2-IRF4/c-MYC信号轴是介导MM细胞来那度胺耐药的重要途径。本课题拟对该机制进行全面阐述，并通过体内外实验探讨BTK抑制剂克服来那度胺耐药的可行性及KPNA2在MM患者的临床预后价值。

BTK signaling pathway and BTK inhibitors (such as ibrutinib) have been widely understood and successfully used in the treatment of different B-NHLs such as chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and Waldenstrom macroglobulinemia (WM). However, the mechanism that BTK signaling pathway involved in multiple myeloma and its clinic value have not been well established yet. Our previous study has showed elevated expression of BTK in myeloma cells led to AKT/WNT/b-catenin–dependent upregulation of key stemness genes (OCT4, SOX2, NANOG and MYC) and induced resistance to widely used anti-myeloma drugs. To explore the correlation and its mechanism between BTK pathway and lenalidomide resistance in MM, we further overexpressed BTK in ARP1 myeloma cells, and found accelerated cell proliferation in ARP1 BTK OE cells compared to BTK EV cells after treatment with lenalidomide (10 uM) for six days which indicated BTK overexpression could induce myeloma cells resistant to lenalidomide. We exerted the analysis of gene expression profiles (GEP) using the Affymetrix U133 Plus 2.0 microarray between OCI-MY5 shBTK and control cells, and found KPNA2 was one of the most downregulated genes. Importantly, overexpressed BTK in ARP1 cells can upregulate the expression of KPNA2 and its effector molecules IRF4 and c-MYC, whereas knockdown of BTK in OCI-MY5 cells can downregulate their expressions. Based on GEP and data analysis from NCBI GEO DataSets (http://www.ncbi.nlm.nih.gov/geo, number GSE19554), we found the mRNA expression level of KPNA2 was obviously higher in MM patients than in patients with monoclonal gammopathy of undetermined significance (MGUS) and normal plasma cells (P<0.001). Moreover, high-risk myeloma patients had higher mRNA expression level of KPNA2 than low-risk patients (P<0.001). The survival analysis indicated higher expression of KPNA2 was a negative predictor for progress-free survival (PFS) and overall survival (OS). So, we hypothesize the overexpression of BTK mediates myeloma cells resistant to lenalidomide through regulation of KPNA2-IRF4/c-MYC axis. In this project, we will comprehensively investigate its mechanism in vitro and vivo study and evaluate the role of CGI1746 (a second-generation BTK inhibitor) in overcoming the resistance to lenalidomide and the prognostic impact of KPNA2 in MM patients which provide some clinical and experimental evidences for BTK and KPNA2 as valuable therapeutic targets.