NUCLEAR ORGANIZATION OF TRANSCRIPTIONAL DOMAINS IN BREAST CANCER

Runx2(Cbfa1/AML3)是一种主要的转录因子，激活/抑制依赖于 核电建筑。Runx2的功能活性需要独特的核基质靶向信号的保真度 (NMTS)在亚核结构域中与共调节蛋白Runx2复合体组织，包括 染色质重塑因子和ECM信号转导通路的介体(如IGF-1，整合素， 转化生长因子/骨形态发生蛋白和c-Src)用于Runx2靶基因的表达。Runx2被发现是骨骼必需的 形成和调节控制细胞生长的基因(P21)，血管募集(VEGF)， 间充质系细胞分化及细胞外基质形成和降解相关蛋白的表达 (骨桥蛋白、骨涎蛋白、基质金属蛋白酶)。最近，Runx2的高表达 转移性乳腺癌细胞系(MDA-MB-231和LCC15)导致破坏性骨溶解的研究报告 骨头上的损伤。根据我们的发现，阻止Runx2靶向功能的Runx2突变 抑制肿瘤进展和骨溶解，我们假设Runx2控制基因的表达 诱导骨内肿瘤进展和骨溶解相关的转移特性 麦克风环境。我们的具体目标是了解以下机制：1) 内源性Runx2在转移性乳腺癌细胞中的作用和2)亚核靶向缺陷 Runx2突变蛋白(STDmRunx2)抑制Runx2靶基因的表达，阻断肿瘤生长和 体内溶骨作用。人转移性乳腺癌细胞MDA-MB-231的体外分子和体内检测 表达WT和STD突变的Runx2蛋白的癌细胞，我们将解决：1)Runx2对 转移细胞中过度活跃的信号通路(项目1)；2)Runx2介导组蛋白的作用 修饰(HDACs和HATS)和SWI/SNF染色质重塑因子控制靶基因 乳腺癌细胞(项目2)；3)WT和STDmRunx2蛋白诱导的表型变化和 细胞系(项目1、2和3)在体内的命运；以及4)Runx2在肿瘤发生发展中的潜在作用。 原发乳腺肿瘤(附项目2)。 报告摘要：转移性乳腺癌最常发生在骨骼。据估计，70%的发病率 转移性乳腺癌患者的骨质破坏与肿瘤发生时有关 细胞在骨骼中生长。我们发现阻断一种主要调节蛋白Runx2的独特性质 激活转移细胞中高表达的基因，可以防止肿瘤生长和骨溶解损害 骨头。通过解决导致这种显著效果的机制，一种潜在的治疗策略 可以开发出预防这种晚期乳腺癌的药物。

Runx2 (Cbfa1/AML3) is a master transcription factor that activates/represses target genes dependent on nuclear architecture. Runx2 functional activity requires the fidelity of a unique nuclear matrix targeting signal (NMTS) that organizes in subnuclear domains Runx2 complexes with co-regulatory proteins that include chromatin remodeling factors and mediators of ECM signal transduction pathways (e.g., IGF-1, integrin, TGF/BMP and c-Src) for expression of Runx2 target genes. Runx2 was discovered as essential for skeletal formation and regulates genes that control cell growth (p21), recruitment of blood vessels(VEGF), differentiation of mesenchymal lineage cells and expression of proteins for ECM formation and degradation (osteopontin, bone sialoprotein, matrix metalloproteinases). Recently, high Runx2 expression has been reported in metastatic breast cancer cell lines (MDA-MB-231 and LCC15) that result in destructive osteolytic lesions in bone. Based on our findings that mutations in Runx2 which block Runx2 targeting functions and inhibit tumor progression and osteolysis in bone, we postulate that Runx2 controls expression of genes inducing metastatic properties associated with tumor progression and osteolysis in the bone micfoenvironment. Our specific aims are directed to understanding the mechanisms by which 1) endogenous Runx2 functions in metastatic breast cancer cells and 2) the subnuclear targeting deficient Runx2 mutant protein (STDmRunx2) inhibits expression of Runx2 target genes and blocks tumor growth and osteolysis in vivo. Using in vitro molecular and in vivo assays of human MDA-MB-231 metastatic breast cancer cells expressing WT and STDmutant Runx2 proteins, we will address: 1) the Runx2 response to signaling pathways hyperactive in metastatic cells (with Project 1); 2) the role of Runx2 mediated histone modifying (HDACs and HATs) and SWI/SNF chromatin remodeling factors in the control of target genes in breast cancer cells (with Project 2); 3) the phenotype change induced by WT and STDmRunx2 proteins and the in vivo fate of the cells lines (with Projects 1,2 and 3); and 4) a potential role of Runx2 in development of primary mammary tumors (with Project 2). Lay Summary: Metastatic breast carcinomas most frequently occur in bone. An estimated 70% morbidity of patients with metastatic breast cancer is associated with the destruction of bone that occurs when the tumor cells grow in bone. We have discovered that blocking a unique property of a master regulatory protein Runx2 that activates genes highly expressed in metastatic cells, can prevent tumor growth and osteolytic lesions in bone. By addressing the mechanisms accounting for this remarkable effect, a potential therapeutic strategy can be developed to prevent this end-stage of breast cancer.