Bit1 as a tumor suppressor and a therapeutic target in NSCLC

 描述（申请人提供）：Bit 1作为NSCLC的肿瘤抑制因子和治疗靶点摘要在过去的三年里，本实验室的工作在Bit 1功能生物学领域做出了重大贡献，特别是在非小细胞肺癌（NSCLC）的失巢凋亡抗性和致瘤性方面，NSCLC是一种致命的和最常见的肺癌形式. Bit 1是一种线粒体蛋白， 在细胞粘附丧失后，细胞质中的细胞凋亡，并与转录调节蛋白氨基末端分裂增强子（AES）结合以触发半胱天冬酶非依赖性细胞凋亡。我们的研究表明，NSCLC细胞很可能绕过这一途径，成为抗失巢凋亡和锚定独立的，并提供了第一个证据的肿瘤抑制功能的Bit 1在NSCLC。重要的是，我们最近的研究结果表明，Bit 1除了其失巢凋亡功能外，还可以负调节NSCLC细胞中的上皮间质转化（EMT）。因此，所观察到的Bit 1的肿瘤抑制功能可能与其促进失巢凋亡和抑制EMT的双重作用有关。Bit 1的这种新的EMT调节功能强调了其规避NSCLC侵袭性和转移性表型的潜在效用。与作为肺肿瘤抑制因子的Bit 1一致，TLE 1辅阻遏物（唯一已知的Bit 1功能抑制剂）最近被鉴定为肺特异性癌基因。我们的工作有助于阐明TLE 1致癌通路的机制，部分通过阻断Bit 1凋亡通路和促进NSCLC细胞中的EMT。我们的集体数据支持一个模型，其中Bit 1的功能关闭生存和EMT促进基因调控功能的TLE 1在AES依赖的方式。在这个项目的继续，我们将调查我们的假设，Bit 1是一个抑制剂的肺上皮细胞转化在体外和肺肿瘤的发生和癌症转移在体内通过其抑制作用的致癌TLE 1转录程序。为了检验这一假设，我们提出了以下具体目标：1）研究Bit 1/AES/TLE 1途径在人肺上皮细胞恶性转化中的作用，2）确定Bit 1/AES复合物的形成和活性以及Bit 1-AES复合物对TLE 1基因调节功能的调节的潜在机制，和3）确定增强和抑制Bit 1和/或TLE 1表达对NSCLC体内致瘤性和转移的影响。这些拟议的研究将推进关于Bit 1通路调节肺癌发生和进展的机制的基础知识，并将有助于该通路在肺癌治疗中的潜在翻译。PHS 398（Rev. 5/01）页

 DESCRIPTION (provided by applicant): Bit1 as a tumor suppressor and a therapeutic target in NSCLC Abstract The work in this laboratory supported by this grant in the past three years has made significant contributions to the field of Bit1 functional biology particularly in the contxt of anoikis resistance and tumorigenicity of Non- Small Cell Lung Carcinoma (NSCLC), a deadly and the most prevalent form of lung cancer. Bit1 is a mitochondrial protein that is released to the cytoplasm following of loss of cell attachment, and associates with the transcriptional regulator protein Amino-terminal Enhancer of Split (AES) to trigger caspase-independent apoptosis. Our studies have shown that NSCLC cells are likely to bypass this pathway to become anoikis resistant and anchorage independent and provide the first evidence of the tumor suppressive function of Bit1 in NSCLC. Importantly, our recent findings indicate that Bit1 in addition to its anoikis function may negatively regulate Epithelial Mesenchymal Transition (EMT) in NSCLC cells. Hence, the observed tumor suppressive function of Bit1 may relate to its dual role in promoting anoikis and inhibiting EMT. This novel EMT regulatory function of Bit1 underscores its potential utility to circumvent the aggressive and metastatic phenotype of NSCLC. In line with Bit1 as a lung tumor suppressor, the TLE1 corepressor, a sole known inhibitor of Bit1 function, has recently been identified as a lung specific oncogene. Our work has contributed to the elucidation on the mechanism of the TLE1 oncogenic pathway, in part through blocking the Bit1 apoptotic pathway and promoting EMT in NSCLC cells. Our collective data supports a model wherein Bit1 functions to turn off the survival- and EMT-promoting gene regulatory functions of TLE1 in an AES dependent manner. In continuation of this project, we will investigate our hypothesis that Bit1 is a suppressor of lung epithelial cell transformation in vitro and lung tumorigenesis and cancer metastasis in vivo through its inhibitory effect on the oncogenic TLE1 transcriptional program. To test the hypothesis, we propose the following specific aims: 1) to study the role of the Bit1/AES/TLE1 pathway in the malignant transformation of human lung epithelial cells, 2) to determine the mechanism underlying the formation and activity of the Bit1/AES complex and the regulation of the TLE1 gene regulatory functions by the Bit1-AES complex, and 3) to determine the effects of enhanced and suppressed Bit1 and/or TLE1 expression on tumorigenicity and metastasis of NSCLC in vivo. These proposed studies will advance the fundamental knowledge on the mechanism by which the Bit1 pathway regulates lung tumorigenesis and progression and will contribute to potential translation of this pathway in the treatment of lung cancer. PHS398 (Rev. 5/01) Page Continuation Format Page