多发性骨髓瘤化疗药物敏感基因的鉴定与作用机理研究

Chemotherapy agents are extremely important in the treatment of liquid malignancies, such as multiple myeloma (MM). Unfortunately, chemotherapy resistance in MM therapy is the most significant cause of treatment failure. The ability to predict, treat, or circumvent resistance is extremely likely to improve clinical outcomes. Thus, identification of novel genes that play a crucial role in MM progression and chemosensitivity is necessary to understand this disease better at the molecular level. Moreover, these genes and their products may serve as new therapeutic targets for MM, whose expression could improve patient outcomes or served as a predictor for chemotherapy outcome. To identify potential chemosensitivity genes, establishing a high-throughput method for validation of targets becomes urgently needed. Toward this purpose, we have successfully developed a high-throughput siRNA based functional target validation approach and identified a group of potential chemosensitivity genes. Our preliminary studies focusing on one of the candidate gene, ZO1 (zonula occludens 1), suggested that targeting ZO1 led to tumor cell resistant to several chemotherapy agents, including doxorubicin (Dox), cisplatin (Cis), methotrexate (MTX), and bortezomib. Further analysis with 264 bortezomib treated MM patients indicated that expression level of ZO1 correlated with patient response to bortezomib treatment. Two clones and pooled RPMI 8226 MM cell line, which were developed against bortezomib treatment in our lab, showed loss of ZO1 expression, suggesting a role of ZO1 may play in bortezomib resistance development. More importantly, ZO1 targeting in myeloma cells resulted in cell resistance to bortezomib treatment. .Thus, these findings have led us to the rational for the proposed research, which will validate the roles of ZO1 gene in sensitizing chemotherapeutic agents in MM: 1) Examining the ZO1 expression in representative MM cell lines and primary samples, and overexpressing or knocking down ZO1 expression to investigate its role in sensitizing chemotherapeutic agents in MM with clinical therapy drugs, including bortezomib, thalidomide, pegylated liposomal doxorubicin, and lenalidomide; 2) Performing expression profiling for ZO1 gene in representative MM cell lines and animal models to determine the molecular mechanism of ZO1 in MM cell drug resistance development. .Taken together, successful completion of these studies will therefore reveal a novel chemosensitivity gene, which will lay the foundation for further clinical studies. Moreover, in the clinical arena, they may form a basis for algorithms to help predict chemosensitivity based on baseline gene expression profiles in the future, and may provide the strategies aimed at enhancing chemosensitivity by increasing expression of target genes of interest.

肿瘤细胞耐药性产生是肿瘤化疗失败的主要原因，特别是对于严重依赖化疗为主要治疗手段的血液肿瘤，比如骨髓瘤来说，解决耐药性产生的原因、找到决定化疗敏感性的基因是一个迫切而且意义重大的课题，不仅可以在分子水平上更好的了解肿瘤耐药性产生的机制，而且这些基因有望作为新的治疗靶点和个性化治疗检测标记物。因此我们利用 RNA 干扰文库，在国际上首次筛选出了一组化疗药物敏感候选基因，经过前期工作验证，发现ZO1（zonula occludens 1）基因的表达有可能代表了对万珂等化疗药物是否敏感的关键因子。我们据此提出了一个中心假设，即ZO1基因代表了新型骨髓瘤化疗药物敏感基因，并制定了一系列研究方案对该基因在耐药性发生上的作用进行深入验证，并对其分子作用机理展开研究。

蛋白酶体抑制剂药物在临床上的应用虽然极大改变了多发性骨髓瘤的治疗效果，但是这些药物的使用主要依靠临床经验来施行，而且肿瘤细胞耐药性的出现成为了最终治疗失败的主要原因。因此，解决耐药性产生的原因、找到决定化疗敏感性的基因是一个迫切而且意义重大的课题，不仅可以在分子水平上更好的了解肿瘤耐药性产生的机制，而且这些基因有望作为新的治疗靶点和个性化治疗检测标记物。我们首次证实了TJP1分子（也称作ZO-1）是一种新型的浆细胞蛋白酶体抑制剂易感性的决定因素。TJP1抑制具有催化活性的免疫蛋白酶体亚基PSMB8和PSMB9的表达，降低蛋白酶的活性，从而提高了蛋白酶体抑制剂在体外和体内的敏感性。对TJP1作用机理的深入研究显示：TJP1通过抑制EGFR/JAK1/STAT3信号通路来实现对PSMB8和PSMB9表达的控制。在临床上，我们发现当患者骨髓瘤细胞高表达TJP1时，患者表现出了对硼替佐米治疗的良好应答以及更长的生存期，这些发现进一步支持了TJP1作为一个生物标记物来鉴定对硼替佐米治疗效果的可能性，从而使得病人可以从蛋白酶体抑制剂的治疗中收益。.该研究成果已投递Cancer Cell，获得审稿人修改要求，正在修改之中。