Cell Death Regulation in Lumen Formation and Oncogenesis

描述(申请人提供)：腺体组织中的上皮细胞，如乳房，被组织成导管和特殊的球形结构，其中包含围绕中空管腔的单层腔上皮细胞。维持这种特殊的结构和抑制异常的细胞增殖是通过控制限制细胞的生存来实现的，这些细胞增殖到中空的腔内或正常的壁龛外。我们以前的研究已经提供了证据表明，导致上皮单分子层外细胞死亡的一个主要因素是缺乏适当的基质附着。此外，我们发现，在缺乏适当基质的细胞中，凋亡和非凋亡性死亡过程都被激活。异常增殖细胞的存活依赖于对这两个死亡过程的逃避。在这个方案中，我们描述了三种不同的实验模型-1)培养中悬浮的、无基质的乳腺上皮细胞，2)在重组基底膜蛋白中培养的3D腺泡结构，以及3)青春期小鼠乳腺的末端芽(TEB)在体内。利用这些模型系统，我们将阐明缺乏适当基质附着的细胞的凋亡性和非凋亡性死亡的机制。此外，我们将使用有偏见的通路解剖研究和无偏见的siRNA筛选来研究癌基因介导的逃避这些死亡机制的机制。最后，我们将研究促凋亡蛋白Bim在肿瘤发生和发展中的重要性。我们之前已经证明，在所有三个实验模型中，BIM都是细胞凋亡所必需的。本申请中提出的研究将调查Bim在几个小鼠肿瘤模型中表达缺失或增加的后果，并检测Bim在人类乳腺肿瘤中的表达。这些研究将提供维持肿瘤细胞存活所需的细胞通路、凋亡蛋白在乳腺肿瘤进展中的作用等有价值的信息，并有可能确定治疗消除肿瘤细胞的靶点。

DESCRIPTION (provided by applicant): Epithelial cells within glandular tissues, like the breast, are organized into ducts and specialized spherical structures containing a monolayer of luminal epithelial cells surrounding a hollow lumen. Maintenance of this specialized architecture and suppression of aberrant cell proliferation is mediated by controls that restrict the survival of cells which proliferate into the hollow lumen or outside of their normal niche. Our previous studies have provided evidence that a major factor contributing to death of cells outside the epithelial monolayer is lack of appropriate matrix attachment. In addition, we found that both apoptotic and non-apoptotic death processes are activated in cells deprived of their appropriate matrix. Survival of aberrant proliferating cells is dependent on escape from both of these death processes. In this proposal, we describe studies, using three different experimental models- 1) Suspended, matrix-deprived breast epithelial cells in culture, 2) 3D acinar structures cultured in reconstituted basement membrane proteins, and 3) Terminal end buds (TEBs) of pubertal mouse mammary glands in vivo. Using these model systems, we will elucidate the mechanisms apoptotic and non- apoptotic death of cells lacking proper matrix attachment. In addition, we will examine the mechanisms involved in oncogene-mediated escape from these death mechanisms using both biased pathway dissection studies and unbiased siRNA screens. Lastly, we will examine the importance of one proapoptotic protein, Bim, in tumor initiation and progression. We have previously shown that Bim is required for apoptosis in all three experimental models. The studies proposed in this application will investigate the consequences of loss or gain of Bim expression in several mouse tumor models and examine Bim expression in human breast tumors. These studies will provide valuable information on the cellular pathways that are required for maintenance of tumor cell survival, the role of apoptotic proteins in breast tumor progression, and potentially identify targets for therapeutic elimination of tumor cells.