基于Connexin43介导的缝隙连接细胞间通讯的乳腺癌溶骨性骨转移机制研究

Breast cancer bone metastasis is an important cause of death in breast cancer patients. With its pathogenesis remains unclear, the tranditional therapeutic strategies targeting osteoclasts are not effective for bone metastasis treatment. Osteocytes account for approximately 90% amongst all cell types in bone tissue, while their roles in bone metastasis remain to futher elucidate. Gap junction is the most important structural and functional feature of osteocyte. Previously we found breast cancer bone metastasis could trigger changes in the expression and distribution of Connexin43(Cx43), weaken gap junction and induce osteocyte apoptosis, suggesting a potential role of osteocytic Cx43-mediated gap junction in bone metastasis. Based on established tumor bone metastasis mouse model and in vitro cell-cell coculture system, this project aims to illustrate the effects and regulatory mechanisms of breast cancer cells on Cx43-mediated gap junction and apoptosis in osteocytes, clarify the biological roles and functional mechanisms of osteocytic Cx43-mediated gap junction changes, and explore the influences of conditional knock-out of osteocytic Cx43 on breast cancer bone metastasis using transgenic mice model. The implementation of this project is expected to further reveal the importance of osteocytes in bone pathology, and provide new ideas for the development of bone metastasis therapeutic strategies targeting interactions between tumor and bone microenvironment.

乳腺癌骨转移是导致乳腺癌患者死亡的重要原因。目前乳腺癌骨转移的病理机制仍不十分明确，传统的仅抑制破骨细胞活性的治疗方案无法有效治疗骨转移。骨组织细胞中90%以上是骨细胞，而其在骨转移中的角色研究甚少。缝隙连接是骨细胞的重要结构与功能特征。前期我们发现乳腺癌骨转移引起骨细胞缝隙连接蛋白43（Connexin43，Cx43）表达与分布改变，缝隙连接减弱及细胞凋亡，提示骨细胞Cx43介导的缝隙连接可能参与了骨转移。本项目拟利用骨转移动物模型和体外细胞共培养模型，阐明乳腺癌细胞对骨细胞Cx43介导的缝隙连接与凋亡的影响及调控机制，明确乳腺癌骨转移中骨细胞Cx43缝隙连接变化的生物学功能与作用机制，并利用转基因小鼠模型探究条件性敲除骨细胞Cx43对乳腺癌骨转移的影响。项目的实施有望进一步揭示骨细胞在骨病理中的重要性，为靶向肿瘤细胞-骨微环境相互作用的骨转移防治策略开发提供新思路。

乳腺癌骨转移是晚期乳腺癌患者常见病症，传统仅抑制破骨细胞活性的治疗方式无法有效治疗骨转移，影响患者存活期与生存质量，目前其机制尚未完全明确。在本项目资助下，我们成功构建了乳腺癌骨转移体内、外研究模型；通过乳腺癌细胞与骨细胞共培养前后的转录组测序及实时定量聚合酶链反应等检测手段，成功筛选出乳腺癌细胞调控骨细胞连接蛋白Cx43表达的重要调控因子TNFSF9，并探究了其影响Cx43表达的作用与调控机制；通过多种手段研究了乳腺癌细胞分泌因子TNFSF9调控骨细胞Cx43影响破骨与成骨的作用与机制。本研究初步阐明了乳腺癌细胞影响骨细胞Cx43参与调控乳腺癌骨转移、影响骨微环境稳态的新作用与新机制，为溶骨性骨转移等骨疾病的治疗提供了理论基础和新的思路。