连接蛋白Cx43羧基末端信号在MM细胞归巢及生存中的作用

Multiple myeloma(MM) is a fatal hematological malignancy that develops within the bone marrow microenvironment and characterized by the uncontrolled clonal proliferation of malignant plasma cells within the bone marrow. Despite the presence of a variety of chromosomal aberrations, translocations and mutations in essential growth and tumor suppressor genes in MM cells, oncogenomic studies have identified few differences distinguishing monoclonal gammopathy of unknown significance from MM. This finding highlights the essential role of the bone marrow (BM) microenvironment in disease maintenance and progression. Indeed, direct and indirect interactions with other cells within the liquid milieu of the BM environment are key requirements for MM pathogenesis, MM cell growth, survival, migration and drug resistance. How this microenvironment becomes so supportive of MM, and the contribution and interaction of the various components of the microenvironment to enhancing MM growth are only beginning to be understood. This microenvironment is composed of generically denominated stromal cells and osteoblasts(OBs). Cell-to-cell contact between bone OBs and stromal cells and MM cells has been recently proposed as a pivotal regulatory interaction in the growth and survival of malignant plasma cells. Gap junctions (GJs) represent the best known intercellular communication (IC) system and are membrane-spanning channels that facilitate intercellular communication by allowing small signaling molecules to pass from cell to cell. Studies showed that Cx43 in particular has a supportive function on normal hematopoiesis, and GJs thereby contribute to the stromal regulation of clonal growth of hematopoietic progenitors. Our previous studies showed that OBsinduced from bone marrow mesenchymal stem cells supported survival and proliferation of MM cells, especially when the MM cells were cultured in medium containing dexamethasone. we demonstrated that MM do express Cx43, that they can in fact communicate with OBs through GJs, and we continue to elucidate the mechanisms by which MM interact with OBs. However, the specific role of Cx43 in the growth and survival of MM cells remains largely unknown. In addition to the identification of permeable metabolites affecting growth it is essential to characterize connexin-linked intracellular signaling pathways and their role in growth-related gene expression. In this context, identification and study of the multiple interacting partners of connexins, and the regulation of connexin function by phosphorylation of its various sites stand to provide important cues. The attractive, but still theoretical, possibility of direct,nuclear effects of connexins or connexin fragments merits further investigation. In addition,specific pathway of connexin Cx43 in MM may be exploited therapeutically.

多发性骨髓瘤（MM）是一种恶性浆细胞疾病，具有干细胞特性的MM细胞归巢并定居于骨髓,是肿瘤的发生和发展的关键。细胞间隙连接蛋白Cx43，其羧基端有多个磷酸化位点，并可作为胞内蛋白质相互作用平台，在肿瘤的生长和转移中发挥作用，近年倍受关注。我们的前期研究发现成骨细胞（OBs）及前体细胞主要表达Cx43；支持MM细胞生长，抑制地塞米松诱导的细胞调亡，共培养后触发OBs细胞Cx43羧基末端磷酸化及多种生长相关基因表达变化，促进MM细胞膜表面黏附分子重分布并激发其极化，可能参与MM的归巢和生存，但确切机制尚需进一步探讨。本研究以Cx43为靶分子，拟采用定点突变、shRNA干扰、流式细胞术、qPCR、蛋白印迹及活体显象等方法分析Cx43非通道依赖信号在MM细胞生存、迁移及体内分布中作用，观察Cx43羧基末端信号在MM细胞归巢和生存调节中的作用，从不同角度探讨MM的发病机，并寻找新靶分子。

多发性骨髓瘤（MM）是浆细胞恶性增殖性疾病，目前仍是一种不可治愈的疾病。在MM发病初期骨髓瘤细胞首先进入外周循环血液，再进入骨髓，并依靠患者骨髓微环境进行增殖、浸润，最终发病并引起一系列相关症状。骨髓微环境是一个具有多重功能的复杂网络结构，由多种细胞组成，MM占据的成骨细胞（OBs）巢,在肿瘤的发生和发展的关键,近年倍受关注。Cx43是一种重要的细胞间隙连接蛋白。我们的前期研究发现OBs主要表达Cx43,并支持MM细胞生长，抑制地塞米松诱导的细胞调亡。可能与BOs和MM细胞相互作用有关，但确切机制尚需进一步探讨本研究以OBs巢为切入点，Cx43为靶分子，观察Cx43分子胞内段信号大该过程中的作用。本研究采用多种生物学方法分析OBs在MM细胞生存及增殖中的作用，尤其是细胞相互作用过程中Cx43羧基端信号变化对MM生存、增殖及细胞因子分泌的影响，在此基础上，构建了含有Cx43-N和Cx43-C的转基因细胞，建立了Cx43基因敲除的小鼠模型，探讨Cx43信号对MM细胞迁移、增殖体及内分布的作用从不同角度探讨MM的发病机制，寻找新的靶分子。