Cell Death Regulation in Lumen Formation and Oncogenesis

描述（由申请方提供）：腺组织（如乳腺）内的上皮细胞被组织成导管和特化球形结构，其中包含围绕中空管腔的单层管腔上皮细胞。这种特化结构的维持和异常细胞增殖的抑制是由限制增殖进入中空腔或在其正常小生境之外的细胞的存活的控制介导的。我们以前的研究提供的证据表明，一个主要因素，导致细胞死亡的上皮单层外缺乏适当的基质附着。此外，我们发现，细胞凋亡和非细胞凋亡的死亡过程中被激活的细胞剥夺了适当的矩阵。异常增殖细胞的存活依赖于从这两种死亡过程中逃脱。在这个建议中，我们描述了研究，使用三种不同的实验模型- 1）悬浮，基质剥夺的乳腺上皮细胞培养，2）三维腺泡结构培养在重建的基底膜蛋白，和3）终末芽（TEB）的青春期小鼠乳腺在体内。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和非凋亡性死亡的机制。此外，我们将使用偏倚通路解剖研究和无偏倚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，我们将研究促凋亡蛋白Bim在肿瘤发生和发展中的重要性。我们以前已经表明，Bim是所需的所有三个实验模型中的细胞凋亡。本申请中提出的研究将研究几种小鼠肿瘤模型中Bim表达丧失或获得的后果，并检查人乳腺肿瘤中的Bim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，并可能确定肿瘤细胞治疗消除的靶点。

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.