miR-214-3p通过调控破骨细胞分化对乳腺癌溶骨性骨转移的影响

Clinical treatment for osteolytic bone metastasis of breast cancer remains a major challenge. Many studies demonstrated that miRNAs play an important role in the pathogenesis of osteolytic bone metastasis of breast cancer through regulating osteoclast differentiation and osteoclastic bone resorption. Our preliminary data showed that miR-214-3p induced osteoclast differentiation and osteoclastic bone resorption through targeted inhibition of tumor necrosis factor receptor-associated factor 3 (Traf3). Next, we found that miR-214-3p level and osteoclast differentiation-related parameters were both higher in bone tissues form patients with osteolytic bone metastasis of breast cancer and xenografted nude mice models of human breast cancer metastasis, whereas the level of TRAF3 protein was lower when compared with their corresponding control groups. Furthermore, the data from a small sample size implied that targeted miR-214-3p inhibition within osteoclasts could attenuate bone resorption and bone metastasis in xenografted nude mice. All these evidences fully support our further hypothesis that miR-214-3p could contribute osteolytic bone metastasis of breast cancer. We will test the hypothesis through two in vivo studies, including the enlargement the sample size of human breast cancer metastasis-xenografted nude mice during targeted treatment with miR-214-3p (miR-214-3p targeted treatment) and constructing xenografted model of human breast cancer metastasis in osteoclast-specific miR-214-3p knock-out mice (miR-214-3p gene intervention). The current proposal would provide a novel drug targets for therapeutic intervention in osteolytic bone metastasis of breast cancer.

乳腺癌骨转移的临床治疗仍面临严峻挑战。大量研究表明miRNAs调控的破骨细胞分化及其骨吸收功能在肿瘤骨转移发病中起着重要的作用。我们前期研究发现miR-214-3p可靶向抑制肿瘤坏死因子受体相关因子3（Traf3）的表达来促进破骨细胞的分化及其骨吸收功能；在乳腺癌骨转移患者和移植性人乳腺癌骨转移裸鼠的骨组织中，miR-214-3p和破骨细胞相关的指标都是升高的，而TRAF3表达则是降低的；抑制破骨细胞内miR-214-3p后，小样本量的数据提示骨转移裸鼠的骨破坏和骨转移程度有所减轻。这些证据充分支持我们进一步的体内研究假设：通过扩大乳腺癌骨转移裸鼠靶向治疗的样本量和构建破骨细胞内特异性敲除miR-214-3p的乳腺癌骨转移模型，从miR-214-3p的靶向治疗和基因敲除两方面，检测miR-214-3p对乳腺癌骨转移的影响，获得的证据有望为乳腺癌骨转移的干预治疗提供新的药物作用靶点。

乳腺癌骨转移的临床治疗仍面临严峻挑战。大量研究表明miRNAs调控的破骨细胞分化及其骨吸收功能在肿瘤骨转移发病中起着重要的作用。我们的研究发现：在乳腺癌溶骨性骨转移患者中，miR-214-3p以及Trap和Ctsk mRNA的表达明显高于非骨转移患者，并且miR-214-3p的表达水平分别与Trap和Ctsk mRNA的表达水平呈正相关；在人乳腺癌骨转移裸鼠的骨组织中，miR-214-3p、破骨细胞数量和破骨细胞吸收表面也是逐渐增加的，并且骨组织中miR-214-3p的表达水平分别与破骨细胞数量和破骨细胞吸收表面是呈正相关的。分子生物学预测软件和荧光素酶报告基因实验证实miR-214-3p可通过靶向抑制肿瘤坏死因子受体相关因子3（TRAF3）的蛋白表达，抑制了NFATc1及其TRAF3下游信号分子NF-κB（p65）和NF-κB 诱导激酶 (NIK)的表达，从而抑制了破骨细胞的分化。为了进一步验证上述实验结果及miR-214-3p对乳腺癌骨转移的影响，一方面，我们通过左心室注射方式，将萤光素酶标记的人源性乳腺癌MDA-MB-231-luc-D3H2LN细胞悬液注射到裸鼠左心室，构建移植性人乳腺癌溶骨性骨转移裸鼠模型，实验结果发现移植性人乳腺癌溶骨性骨转移裸鼠给予antagomir-214-3p后，可显著性抑制破骨细胞内miR-214-3p的含量，进而减少了骨组织中破骨细胞的数量，降低了骨破坏的程度和转移灶的发生率。另一方面，构建破骨细胞内miR-214-3p特异性敲除的移植性人乳腺癌骨转移裸鼠模型，miR-214-3p基因敲除后，也可显著性抑制破骨细胞内miR-214-3p的含量，进而减少了骨组织中破骨细胞的数量，降低了骨破坏的程度和转移灶的发生率，提示抑制破骨细胞内的miR-214-3p可减轻了乳腺癌诱发的溶骨性骨转移。本研究进一步阐明了乳腺癌骨转移的发病机理，为乳腺癌骨转移的干预治疗提供新的药物作用靶点。.通过本项目的实施，申请者以第一作者或通讯作者身份，现已在Scientific Reports、Frontiers in Endocrinology、Frontiers in Pharmacology、Oxidative Medicine and Cellular Longevity等杂志发表学术论文15篇。