TGF-betas in breast cancer progression

TGF-β 在乳腺癌进展中的作用

• 批准号: 7732901
• 负责人: Lalage Wakefield
• 金额: $ 75.55万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7732901
• 关键词: 1-Phosphatidylinositol 3-Kinase; Address; Alleles; Apoptotic; Biological; Biological Models; Cell Line; Cell Proliferation; Clinical; Complex; Coupled; Data; Development; Disruption; Epigenetic Process; Epithelial; Epithelial Cell Proliferation; Epithelial Cells; Epithelium; Equilibrium; Failure; Gene Dosage; Gene Expression; Gene Expression Profile; Genes; Genetic; Genetic Polymorphism; Genome; Genotype; Goals; Growth; Histology; Homeostasis; Human; Incidence; Invasive; Ligands; Maintenance; Malignant Neoplasms; Mammary gland; Mediating; Metastatic to; Mitogen-Activated Protein Kinase Kinases; Molecular; Mus; Neoplasm Metastasis; Normal tissue morphology; Oncogenic; Outcome; Output; Pathway interactions; Patients; Phosphoinositide-3-Kinase, Catalytic, Gamma Polypeptide; Play; Population; Pre-Clinical Model; Process; Production; Property; Proteins; RNA Interference; Risk; Role; Sampling; Signal Pathway; Signal Transduction; Stem cells; Testing; Transforming Growth Factor beta; Transgenic Model; Transgenic Organisms; Tumor Promotion; Tumor Suppression; Tumor Suppressor Proteins; Xenograft Model; Xenograft procedure; base; cancer cell; cancer stem cell; cancer therapy; carcinogenesis; cell type; chromatin immunoprecipitation; functional genomics; genetic regulatory protein; inhibitor/antagonist; insight; interest; malignant breast neoplasm; mammary epithelium; mouse model; neoplastic cell; novel; novel strategies; outcome forecast; prevent; promoter; response; size; tumor; tumor progression; tumorigenesis; 1-Phosphatidylinositol 3-Kinase; Address; Alleles; Apoptotic; Biological; Biological Models; Cell Line; Cell Proliferation; Clinical; Complex; Coupled; Data; Development; Disruption; Epigenetic Process; Epithelial; Epithelial Cell Proliferation; Epithelial Cells; Epithelium; Equilibrium; Failure; Gene Dosage; Gene Expression; Gene Expression Profile; Genes; Genetic; Genetic Polymorphism; Genome; Genotype; Goals; Growth; Histology; Homeostasis; Human; Incidence; Invasive; Ligands; Maintenance; Malignant Neoplasms; Mammary gland; Mediating; Metastatic to; Mitogen-Activated Protein Kinase Kinases; Molecular; Mus; Neoplasm Metastasis; Normal tissue morphology; Oncogenic; Outcome; Output; Pathway interactions; Patients; Phosphoinositide-3-Kinase, Catalytic, Gamma Polypeptide; Play; Population; Pre-Clinical Model; Process; Production; Property; Proteins; RNA Interference; Risk; Role; Sampling; Signal Pathway; Signal Transduction; Stem cells; Testing; Transforming Growth Factor beta; Transgenic Model; Transgenic Organisms; Tumor Promotion; Tumor Suppression; Tumor Suppressor Proteins; Xenograft Model; Xenograft procedure; base; cancer cell; cancer stem cell; cancer therapy; carcinogenesis; cell type; chromatin immunoprecipitation; functional genomics; genetic regulatory protein; inhibitor/antagonist; insight; interest; malignant breast neoplasm; mammary epithelium; mouse model; neoplastic cell; novel; novel strategies; outcome forecast; prevent; promoter; response; size; tumor; tumor progression; tumorigenesis

In FY08, we have focused primarily on elucidating the tumor cell-autonomous components of the switch in activity of TGF-beta from tumor suppressor to pro-progression factor. TGF-beta is a potent inhibitor of the proliferation of epithelial cells, and it has been widely assumed that this property is critical for the ability of TGF-beta to function as a tumor suppressor. However, we have identified a novel tumor suppression mechanism that is independent of direct effects on cell proliferation. Using a breast cancer xenograft model, we have shown that endogenous TGF-betas can suppress tumorigenesis by reducing the size of the putative cancer stem cell population and by promoting differentiation of the highly proliferative cancer progenitor cells. Experimental blockade of TGF-beta response in this model system converted the gene expression profile and histology of the tumor from a differentiated luminal to a less differentiated basal state, which previous clinical breast cancer studies have shown to be associated with a poorer prognosis. We identified the transcriptional regulator Id1 as a critical downstream target of TGF-beta in regulating differentiation, and we propose that molecular changes that block differentiation can selectively block this tumor suppressor effect of TGF-beta, thereby contributing to the metastatic switch. The TGF-beta signal is transduced by two structurally highly related proteins, Smad2 and Smad3, as well as by other signaling cascades such as the MAPK kinase and PI3 kinase pathways. We have hypothesized that the balance between these different signaling pathways may be critical in determining whether the output of the TGF-beta signal is tumor suppressive or tumor promoting. To systematically address this question, we have generated a panel of conditionally immortalized mammary epithelial cells from mice of differing Smad genotypes. This approach allows us more precise control over Smad2/3 levels than can be achieved through RNA interference approaches. We have found that the growth inhibitory and pro-apoptotic responses of the mammary epithelium to TGF-beta require only Smad3 and not Smad2. In contrast, the pro-migratory and pro-invasive effects of TGF-beta require obligatory cooperation between both Smads. The data suggest that Smad3 may be critical for both tumor suppressor and pro-progression responses, while Smad2 is more important for the pro-progression responses. In addition, there are interesting gene dosage effects in the requirement for Smad3, with loss of one allele of Smad3 resulting in loss of the pro-apoptotic response to TGF-beta, while still permitting the other responses. Thus, despite the critical requirement for Smad3 in both tumor suppressive and tumor promoting activities, a reduction in Smad3 is predicted selectively to promote progression. In support of this prediction, we have found that Smad3+/- mice have a higher incidence of metastasis in the MMTV-PVT transgenic mouse model of breast cancer. The potential association between Smad3 polymorphisms and risk of metastatic breast cancer will be investigated. The data from our lab and others implicates Smad3 in both the tumor suppressor and pro-progression effects of TGF-beta on the tumor cell. We hypothesize that genetic or epigenetic changes that occur during cancer progression may alter the Smad3-mediated readout of the TGF-beta signal so that tumor promoting activities dominate. To address this question, we have performed genome-wide chromatin immunoprecipitation to identify Smad3 targets in two closely related cell lines, MCF10Ca1h in which TGF-beta functions as tumor suppressor, and MCF10Ca1a in which TGF-beta functions as a pro-progression factor. Integration of the promoter occupancy data with global gene expression data has yielded core Smad3-based gene signatures that are associated with the two different outcomes. These signatures should yield important insights into mechanisms underlying the switch process, and will be exploited in gene expression based screens to find novel compounds that might reverse the switch and restore the tumor suppressor activities of TGF-beta.

在08财年，我们主要集中于阐明TGF-β从肿瘤抑制剂到促进因子的肿瘤细胞自治成分。 TGF-β是上皮细胞增殖的有效抑制剂，并且已广泛认为该特性对于TGF-β充当肿瘤抑制器的能力至关重要。但是，我们已经确定了一种新型的肿瘤抑制机制，该机制与对细胞增殖的直接影响无关。使用乳腺癌异种移植模型，我们表明内源性TGF-β可以通过减少假定的癌症干细胞群体的大小以及促进高度增殖性癌症祖细胞的分化来抑制肿瘤发生。在该模型系统中，TGF-β反应的实验阻断将肿瘤的基因表达谱和组织学从分化的腔内转化为较不分化的基础状态，以前的临床乳腺癌研究已证明与预后较差有关。我们将转录调节剂ID1确定为调节分化中TGF-beta的关键下游靶标，我们提出，分子变化可以选择性地阻断TGF-β的这种肿瘤抑制效应，从而有助于转移开关。 TGF-β信号由两个结构上高度相关的蛋白SMAD2和SMAD3以及其他信号级联反应转导，例如MAPK激酶和PI3激酶途径。我们假设这些不同的信号通路之间的平衡对于确定TGF-β信号的输出是抑制肿瘤还是肿瘤促进可能是至关重要的。为了系统地解决这个问题，我们已经产生了来自不同SMAD基因型小鼠的有条件永生的乳腺上皮细胞。与通过RNA干扰方法相比，这种方法使我们对SMAD2/3级别的控制更加精确。我们发现，乳腺上皮对TGF-β的生长抑制和促凋亡反应仅需要SMAD3而不需要SMAD2。相比之下，TGF-β的亲迁移和亲侵入性作用需要两种SMAD之间的强制性合作。数据表明，SMAD3对于抑制肿瘤和促进反应至关重要，而SMAD2对于促进反应更为重要。此外，在SMAD3的需求中存在有趣的基因剂量效应，其中一个Smad3等位基因导致对TGF-beta的促凋亡反应的丧失，同时仍允许其他反应。因此，尽管在肿瘤抑制和促进肿瘤促进活性中对SMAD3的要求至关重要，但选择性地预测SMAD3的降低以促进进展。为了支持这一预测，我们发现SMAD3 +/-小鼠在MMTV-PVT转基因小鼠模型中的转移发生率更高。将研究SMAD3多态性与转移性乳腺癌风险之间的潜在关联。我们实验室和其他的数据暗示了TGF-β对肿瘤细胞的肿瘤抑制和促进作用中的SMAD3。 我们假设癌症进展过程中发生的遗传或表观遗传变化可能会改变TGF-β信号的SMAD3介导的读数，从而促进肿瘤促进活性占主导地位。为了解决这个问题，我们已经进行了全基因组染色质免疫沉淀，以鉴定两个密切相关的细胞系中的SMAD3靶标MCF10CA1H，其中TGF-beta充当肿瘤抑制剂，而TGF-Beta在其中TGF-10CA1A充当促进因子。启动子占用数据与全局基因表达数据的集成产生了与两个不同结果相关的基于核心SMAD3的基因特征。这些特征应产生对开关过程基础机制的重要见解，并将在基于基因表达的筛选中利用，以找到可能逆转开关并恢复TGF-β肿瘤抑制活性的新型化合物。