MicroRNA-182靶向调节PDCD4在STAT1介导的多发性骨髓瘤CAM-DR中的作用

The regulation of cell apoptosis has been reported to play a crucial role in cell adhesion mediated-drug resistance (CAM-DR) in multiple myeloma. STAT1 is essential in the process of cell apoptosis. PDCD4 is considered to participate in the progression of cell apoptosis and the development of drug resistance. Previous study demonstrated that microRNA-182 (miR-182) can promote the chemoresistance by targeting PDCD4 in various tumors. Our preliminary experiments showed that both STAT1 and PDCD4 were correlated with CAM-DR, and they could interact with each other. Furthermore, the combination of PDCD4 with STAT1 was detected to affect the stability and activity of STAT1. Based on these, we inferred that miR-182 may promote STAT1-mediated CAM-DR phenotype via targeting PDCD4 in multiple myeloma. To verify this assumption, firstly, we intend to clarify the mechanism of PDCD4 in regulating the process of CAM-DR. Secondly, the significance of miR-182 expression on targeting PDCD4 expression and sustaining CAM-DR development are determined. Furthermore, the clinical tissues and nude mouses will be used to verify our hypothesis. And the integrative action of the miR-182-PDCD4-STAT1 axis will be identified during the progression of CAM-DR. This project may provide a novel theoretical basis for a better understanding of the abnormal molecular mechanisms of drug resistance in multiple myeloma.

细胞凋亡的调节在多发性骨髓瘤（MM）细胞粘附介导的耐药（CAM-DR）中起关键作用。STAT1是调控细胞凋亡的重要信号传导分子。PDCD4与细胞凋亡、耐药过程密切相关。MicroRNA-182 (miR-182)可通过靶向抑制PDCD4促进肿瘤细胞耐药。课题组预实验发现STAT1、PDCD4均与CAM-DR有关；PDCD4可与STAT1相互作用并影响STAT1稳定性。基于此，推测miR-182可能通过靶向抑制PDCD4增强STAT1稳定性，进而参与CAM-DR进程。本项目拟首先分析PDCD4在CAM-DR中的作用；其次分析miR-182对PDCD4的调节在CAM-DR中的作用；接着分析PDCD4-STAT1相互作用调节机制及其对CAM-DR的影响；最后全面分析miR-182靶向抑制PDCD4对STAT1介导的CAM-DR的影响。课题的研究将进一步阐明CAM-DR的分子机制。

研究miR-182调控PDCD4影响CAM-DR的机制。我们首先证实过表达STAT1促进多发性骨髓瘤细胞增殖能力；接着我们发现过表达STAT1显著降低多发性骨髓瘤细胞对多柔比星的敏感性且过表达STAT1促进CAM-DR；随后我们证实过表达STAT1可增强H929以及MM.1S细胞中IRF2、Bcl-2的蛋白表达水平，并抑制Bax、Cleaved Caspase-3的蛋白表达水平；接下来，我们证实了在多发性骨髓瘤中PDCD4可以与STAT1相互作用；敲低PDCD4促进STAT1第701位酪氨酸（Y701）磷酸化；并且多发性骨髓瘤细胞粘附到纤连蛋白可下调PDCD4的表达；而PDCD4下调可促进多发性骨髓瘤CAM-DR进程；此外，我们还发现多发性骨髓瘤细胞与纤连蛋白粘附后可诱导miR-182表达；在多发性骨髓瘤细胞中miR-182可负性调节PDCD4的表达；而miR-182上调可促进多发性骨髓瘤CAM-DR进程；过表达miR-182可显著增强AKT第473位丝氨酸磷酸化；与此相似，干扰PDCD4也可增强AKT第473位丝氨酸磷酸化。