磷酸化MARCKS介导E2F1-PUMA轴对多发性骨髓瘤耐药的机制研究

多发性骨髓瘤（MM）患者出现原发性和获得性耐药是临床治疗中面临的最大难题，其机制一直未能阐明。我们前期工作中建立了MM耐药特征性的分子谱，其中磷酸化MARCKS（pMARCKS）高表达诱导p27泛素化降解，下调p27Kip1加快细胞周期进程导致耐药。进一步试验证实，多肽MPS靶向抑制pMARCKS后，PUMA异常高表达，而pMARCKS不能直接调控PUMA表达，其下游基因E2F1中可能存在PUMA启动子的结合位点，可见E2F1-PUMA轴对于pMARCKS引起的多药耐药至关重要。本研究拟在此基础上，从200例患者骨髓活检样本分析中总结pMARCKS、E2F1、PUMA对初治及难治复发MM的临床相关性及预后价值，同时从细胞水平和动物模型中深入探讨pMARCKS通过E2F1-PUMA轴在MM耐药调控中的作用位点和分子机制，解析下游效应途径及靶点，为靶向pMARCKS药物研发提供理论基础。

Primary and acquired drug resistance poses formidable challenges in treating Multiple Myeloma (MM) patients. The mechanism of drug resistance is complicated and still not completely clarified. Basing on our preliminary work, we identified and established the molecular characteristics of myeloma resistance, especially phosphorylated form of myristoylated alanine-rich C-kinase substrate (pMARCKS) was overexpressed. pMARCKS promoted cell-cycle progression by inducing p27 ubiquitination degradation and suppressing p27Kip1. This resulted in drug resistance in Myeloma .Additional preliminary experiments provided evidence that p53 upregulated modulator of apoptosis (PUMA) showed extremely high expression after the inhibition of pMARCKS using MPS peptide , however，pMARCKS does not directly activate transcription of the PUMA gene. Moreover，pMARCKS regulated downstream E2F1 which might combine with PUMA via transactivation domain. This suggested the E2F1-PUMA axis play a key role in the drug resistance caused by pMARCKS. Based on our preliminary results, we propose to examine the protein expressions of pMARCKS, E2F1 and PUMA in bone marrow biopsy samples from 200 myeloma patients and summarize the clinical relevance and prognostic value in newly diagnosed and refractory patients. Additionally, the role of pMARCKS through E2F1-PUMA axis in the regulation of drug resistance in myeloma, related molecular mechanisms and the downstream effect pathways/targets will be studied and analyzed in the cell level and animal model. This will provide a theoretical basis to develop small molecule drug targeting pMARCKS.