Apoptotic mechanisms in NSAID chemoprevention

描述(申请人提供)：本提案的重点是确定非甾体类抗炎药诱导的、非COX依赖的、癌前和恶性口腔细胞的凋亡和生长抑制的化学预防机制和分子靶点。需要检验的假设是，NSAIDs对人类癌前和恶性口腔细胞表型的化学预防作用与线粒体触发导致细胞凋亡的分子事件有关。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着关键作用。我们的初步数据表明，塞来昔布通过作用于调节线粒体膜电位稳定性的信号通路的多个组成部分，诱导细胞凋亡和生长抑制，而不是抑制COX-2，并伴随着长时间的细胞周期停滞。线粒体膜电位的丧失导致caspase 9、3和8的激活。这一假设将在人类口腔细胞培养模型(正常、癌前和恶性口腔细胞系)和异种口腔癌细胞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)进行验证。药理学和基因组学方法将被用来确定导致药物诱导的线粒体膜不稳定、细胞凋亡和生长抑制的信号通路的分子靶点。具体目标1将解决假说，并确定塞来昔布/衍生物诱导癌前和恶性口腔细胞凋亡的机制。特异靶2旨在了解塞来昔布及其衍生物诱导的细胞周期停滞与细胞凋亡的关系。具体目标3将验证体外抑制生长和细胞凋亡的分子机制可防止肿瘤在体内扩散和复发的假说。在特定目标4中，我们将在体内确定抑制异种移植瘤生长的分子靶点。本研究的意义在于加深对线粒体在化学预防性药物诱导的口腔癌细胞凋亡中作用的认识，发现和鉴定与非甾体抗炎药诱导的细胞凋亡相关的新的分子靶点，为开发新的口腔癌化学预防性药物奠定基础。

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.