The role of WNT10B and HMGA2 in Lung Metastasis in Triple Negative Breast Cancer

描述（由申请人提供）：乳腺癌是美国和欧洲女性中第二常见的癌症类型。我们对乳腺癌中受致癌突变影响的基因了解甚多；然而，对转移至关重要的分子事件知之甚少，而转移是癌症死亡的主要原因。三阴性（TN）（即缺乏表达[或过表达]ER和HER2，以及孕激素受体[PR]）乳腺癌亚型具有高度转移性。Wnt10b/b- catenin/HMGA2信号在三阴性乳腺癌（TNBC）和基底样癌症中过度激活。我们在一个翻译模型中发现，Wnt10b/¿-catenin信号在肿瘤启动细胞中触发高HMGA2活性和细胞周期增殖，导致人类和小鼠的三阴性乳腺肿瘤。重要的是，我们的研究小组已经证明WNT10B和HMGA2与预测TNBC的生存结果有显著的相关性，HMGA2单独可以预测TNBC的转移。TNBC有转移倾向，主要转移到脑（30%）和肺（40%）。相比之下，其他乳腺癌亚型转移到肝脏（30%）和骨骼（40%）。与其他亚型乳腺癌（ER¿和HER2阳性肿瘤）不同，TNBC没有靶向治疗方法。TNBC的治疗方案仍然是临床的一个主要挑战，因为潜在的分子机制仍然没有很好地理解-特别是它如何优先转移到肺。MMTV-Wnt10b-IRES-LacZ转基因小鼠乳腺肿瘤可引起罕见的自发性原发性肺转移（<0.30%）。然而，wnt10blacz驱动的肿瘤启动细胞在同基因小鼠中强烈诱导肺转移（bbb60 %）。分离的具有间充质干细胞特性的Wnt10bLacZ肺转移瘤细胞表达具有高表达HMGA2和转移定植关键因子的上皮-间充质转化（EMT）标志物。使用特定的Wnt/¿-catenin抑制剂ICG-001和沉默HMGA2可阻断增殖和N-CADHERIN表达，同时恢复E-CADHERIN和WNT7A水平。初步数据表明，沉默HMGA2可以在体内阻断肺转移，并可以调节H3K4me3在b-catenin/CBP hat -活性靶向基因亚群上的状态。我们将研究hmga2介导的表观遗传活性调控EMT和肺转移的主要机制。我们的第一个目标是利用HMGA2沉默的转移小鼠Wnt10bLacZTG细胞和人三阴性乳腺癌细胞系，研究HMGA2在肺转移中的体内作用。我们的第二个目标是通过使用HMGA2、H3K4me3、H3K27me3和H3K9Ac抗体，通过ChIP分析评估emt特征、分化、增殖和肿瘤抑制基因启动子上¿-catenin-CBP/ hat介导的组蛋白修饰的变化，确定HMGA2在肺转移中的功能作用。我们的发现可能会改变转移性TNBC肿瘤的治疗方法。

DESCRIPTION (provided by applicant): Breast cancer represents the second most commonly diagnosed cancer type amongst women in the United States and Europe. Much is known about the genes that are affected by cancer-causing mutations in breast cancer; however, less is known about molecular events that are crucial for metastasis, which is the major cause of cancer mortality. The triple negative (TN) (i.e. lacking expression [or overexpression] of ER and HER2, as well as progesterone receptor [PR]) breast cancer subtype is highly metastatic. Wnt10b/b- catenin/HMGA2 signaling has been shown by our group to over-activated in triple-negative breast cancers (TNBC) and basal-like cancers. We uncovered in a translational model that Wnt10b/¿-catenin signaling triggers high HMGA2 activity and cell cycle proliferation in tumor-initiating cells leading to triple-negative mammary tumors in human and mice. Importantly our group has shown that both WNT10B and HMGA2 have significant correlation with predicting survival outcome and HMGA2 alone could predict metastasis for TNBC. TNBC has a propensity to metastasize, mainly to the brain (30%) and lung (40%). In contrast, other breast cancer subtypes metastasize to liver (30%) and bone (40%). Unlike other subtypes of breast cancer (ER¿ and HER2 positive tumors) there is no targeted therapy for TNBC. A therapeutic regimen for TNBC remains a major challenge in the clinics because the underlying molecular mechanisms are still not well understood-in particular how it preferentially metastasizes to the lung. MMTV-Wnt10b-IRES-LacZ transgenic mouse mammary gland tumors give rise to rare spontaneous primary lung metastasis (<0.30%). However, Wnt10bLacZ-driven tumor-initiating cells robustly induce pulmonary metastasis (>60%) in syngeneic mice. Isolated Wnt10bLacZ lung metastasis tumors cells with mesenchymal stem-cell properties express epithelial-to- mesenchymal transition (EMT) markers featuring high expression of HMGA2 and factors critical for metastatic colonization. Utilizing both a specific Wnt/¿-catenin inhibitor ICG-001 and silencing of HMGA2 blocks proliferation and N-CADHERIN expression with concurrent restoration of E-CADHERIN and WNT7A levels. Preliminary data illustrate that silencing of HMGA2 can block lung metastasis in vivo and can regulate the status of H3K4me3 on a subset of genes that are targeted by b-catenin/CBP HAT-Activity. We will study the underlining mechanism(s) by which HMGA2-mediated epigenetic activity regulates EMT and lung metastasis. Our first aim is to study the in vivo role of HMGA2 in lung metastasis using both metastatic mouse Wnt10bLacZTG cells and human triple negative breast cancer cell lines that have been silenced for HMGA2. Our second aim is to determine the functional role of HMGA2 in lung metastasis by assessing changes in ¿-catenin-CBP/HAT-mediated histone modifications on promoters of EMT-signature, differentiation, proliferation and tumor suppressor genes by ChIP analysis using antibodies to HMGA2, H3K4me3, H3K27me3, and H3K9Ac. Our findings may alter therapeutics for the metastatic TNBC tumors.