Apoptotic mechanisms in NSAID chemoprevention

描述（由申请方提供）：该提案的重点是定义负责NSAID诱导的、COX非依赖性的、癌前和恶性人口腔细胞凋亡和生长抑制的化学预防机制和分子靶点。待检验的假设是NSAID在人癌前和恶性口腔细胞表型中的化学预防作用与线粒体触发导致细胞凋亡的分子事件相关。线粒体在细胞凋亡信号的处理以及导致细胞死亡的致凋亡蛋白的储存和释放中起关键作用。我们的初步数据表明，塞来昔布诱导细胞凋亡和生长抑制，独立于考克斯-2抑制，通过作用于多个组件的信号通路调节线粒体膜电位的稳定性，并遵循延长细胞周期停滞。线粒体膜电位的丧失导致半胱天冬酶9、3和8的活化。将在人口腔细胞培养模型（正常、癌前和恶性口腔细胞系）和异种移植口腔癌细胞SCID小鼠模型中，使用塞来昔布和非COX抑制结构类似物（塞来昔布/衍生物）对该假设进行检验。药理学和基因组学方法将用于定义导致药剂诱导的线粒体膜不稳定性、细胞凋亡和生长抑制的信号传导途径中的分子靶点。具体目标1将阐述塞来昔布/衍生物诱导癌前和恶性人类口腔细胞凋亡的假设并定义机制。具体目标2旨在了解塞来昔布/衍生物诱导的细胞周期阻滞与细胞凋亡的关系。具体目标3将检验生长抑制和凋亡的体外分子机制在体内防止肿瘤扩散和复发的假设。在具体目标4中，我们将在体内鉴定负责异种移植肿瘤生长抑制的分子靶标。本课题的研究意义在于加深我们对线粒体在化学预防剂诱导的细胞凋亡中的作用的理解，鉴定和表征负责NSAID诱导的细胞凋亡的新的分子靶点，并为开发新的人类口腔癌化学预防剂奠定基础。

DESCRIPTION (provided by applicant): The focus of this proposal is to define chemopreventive mechanisms and molecular targets responsible for NSAID induced, COX-independent, apoptosis and growth inhibition of premalignant and malignant human oral cells. The hypothesis to be tested is that the chemopreventive effects of NSAIDs in human premalignant and malignant oral cell phenotypes are associated with mitochondrial triggering of molecular events leading to apoptosis. Mitochondria play a pivotal role in the processing of apoptotic signals, and in the storage and release of apoptogenic proteins leading to cell death. Our preliminary data indicate that celecoxib induces apoptosis and growth inhibition, independent of COX-2 inhibition, by acting on multiple components of signaling pathways regulating the stability of the mitochondrial membrane potential and follows prolonged cell cycle arrest. The loss of mitochondrial membrane potential leads to the activation of caspases 9, 3 and 8. The hypothesis will be tested using celecoxib and non-COX inhibiting structural analogs (celecoxib/derivatives) in a human oral cell culture model (normal, premalignant and malignant oral cell lines) and a xenografted oral cancer cell SCID mouse model. Pharmacological and genomic approaches will be used to define the molecular targets in signaling pathways leading to agent induced mitochondrial membrane instability, apoptosis and growth inhibition. Specific aim 1 will address hypotheses, and define mechanisms, by which celecoxib/derivative induce apoptosis in premalignant and malignant human oral cells. Specific aim 2 is designed to understand the relationship of celecoxib/derivative induced cell cycle arrest and apoptosis. Specific aim 3 will test the hypothesis that the in vitro molecular mechanisms for growth inhibition and apoptosis prevent tumor spread and recurrence in vivo. In specific aim 4 we will identify, in vivo, molecular targets responsible for growth inhibition of xenotransplanted tumors. The significance of this project will be to advance our understanding of the role of mitochondria in chemopreventive agent induced apoptosis, identify and characterizing novel molecular targets responsible for NSAID induced apoptosis and lay the foundation for the development of new chemopreventive agents in human oral cancer.