Cell Death Regulation in Lumen Formation and Oncogenesis

描述（由申请人提供）：腺体组织内的上皮细胞，如乳腺，被组织成导管和特殊的球形结构，其中包含单层管腔上皮细胞围绕中空管腔。这种特殊结构的维持和异常细胞增殖的抑制是通过控制细胞的存活来调节的，这些细胞增殖到空腔或正常生态位之外。我们之前的研究已经提供证据表明，导致上皮单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，凋亡和非凋亡死亡过程都被激活。异常增殖细胞的存活依赖于逃避这两种死亡过程。在这篇文章中，我们描述了使用三种不同的实验模型进行的研究：1)培养的悬浮的、无基质的乳腺上皮细胞，2)重建基底膜蛋白培养的3D腺泡结构，以及3)在体内培养的青春期小鼠乳腺终末芽（TEBs）。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和非凋亡死亡机制。此外，我们将使用偏倚途径解剖研究和无偏倚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，我们将研究一种促凋亡蛋白Bim在肿瘤发生和发展中的重要性。我们之前已经证明，在所有三种实验模型中，Bim都是细胞凋亡所必需的。本申请中提出的研究将调查几种小鼠肿瘤模型中Bim表达缺失或增加的后果，并检查人类乳腺肿瘤中Bim的表达。这些研究将为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提供有价值的信息，并有可能确定治疗性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.