miR-302b调控多发性骨髓瘤微环境中成骨-破骨偶联失衡的分子机制研究

Bone destruction caused by multiple myeloma (MM) remains uncured, uncoupling of bone formation and resorption is the theoretical basis of bone destruction in MM. In recent years, the regulatory mechanism of miRNA in the MM microenvironment has attracted much attention. Our preliminary experiment showed that miR-302b was poorly expressed in bone marrow of MM patients with bone destruction, miR-302b regulated the biological function of MM cells, and further projections indicated that the target genes of miR-302b may be DKK1 and Runx2, and which were highly expressed in MM. Additionally, the literature showed that both DKK1 and Runx2 promoted the uncoupling of bone formation and resorption in MM microenvironment. Therefore, we hypothesize that on the one hand, miR-302b could preserve bone formation activity by down-regulating DKK1, and on the other hand, inhibit osteoclastic activation by down-regulating Runx2, thus reversing the uncoupling of bone formation and resorption in MM microenvironment. In this research, we designed to investigate the clinical relationship between miR-302b and MM patients with bone destruction, and elucidate the effect and downstream molecular mechanism of miR-302b of uncoupling of bone formation and resorption in the MM microenvironment through cell experiments, MM mice xenograft model of MM bone destruction and miR-302b knockout mouse model. Our research may provide a new target for the treatment of MM bone destruction.

多发性骨髓瘤（MM）引起的骨破坏仍无法治愈，MM微环境中成骨-破骨偶联失衡是MM骨破坏的理论基础。近年来，miRNA在MM微环境中的调控机制备受关注。我们前期研究表明miR-302b在MM骨破坏患者中低表达，miR-302b调控了MM细胞生物学功能，进一步预测miR-302b靶基因可能为DKK1和Runx2，且DKK1和Runx2在MM中高表达。同时文献表明，DKK1和Runx2均促进MM微环境中成骨-破骨偶联失衡。本课题提出假说，miR-302b一方面通过下调DKK1挽救成骨活性，另一方面下调Runx2而抑制破骨异常活化，逆转MM微环境中成骨-破骨偶联失衡。我们拟深入探讨miR-302b与MM骨破坏的临床相关性，通过细胞实验、MM骨破坏裸鼠模型、miR-302b基因敲除小鼠模型，揭示miR-302b调控MM微环境中成骨-破骨偶联失衡的作用及其下游分子机制，为MM骨破坏的治疗提供新的靶点。

多发性骨髓瘤（Multiple myeloma, MM）是最常见的血液系统恶性肿瘤之一，通常以骨髓中浆细胞恶性克隆增生为特征。近年来，以骨痛为首发症状的MM患者越来越多，MM溶骨性破坏引起的病理性骨折等骨相关疾病引起了骨科学界的关注。MM骨髓微环境中的成骨-破骨偶联，衡是MM骨破坏的主要原因。DKK1是一种分泌型蛋白，能与细胞膜上Wnt 受体LRP5结合，抑制成骨分化相关的Wnt/β-catenin信号通路。miRNA是一类小分子非编码RNA能够调控包括增殖、凋亡在内的多种生物学过程。前期研究基础发现，miR-302b在MM患者骨髓样本表达水平显著低于对照组。本研究将通过在细胞和分子层面探索 miRNA-302b与DKK1在MM 骨髓微环境成骨分化过程中发挥的具体调控作用；在动物实验中探索 miRNA-302b、DKK1 与 MM 骨破坏之间的相关性，为临床上 MM 骨破坏的治疗策略提供新思路。本课题从临床样本和细胞系中证明了miRNA-302b 在多发性骨髓瘤中低表达，并阐述了miRNA-302b 对多发性骨髓瘤细胞生物学功能的影响，为研究多发性 骨髓瘤的侵袭、转移提供了新的理论方向。 本课题阐述了 miRNA-302b 能够降低多发性骨髓瘤细胞对成骨分化过程的抑制作用，为研究多发性骨髓瘤成骨-破骨偶联失衡提供了新靶标。 本课题证明了 miRNA-302b 能够通过下调多发性骨髓瘤细胞中 DKK1 的表达，进而抑制多发性骨髓瘤诱导的骨破坏进程，为治疗多发性骨髓瘤骨病提供了新方向、新策略。