Atypical PKC signaling in lung cancer stem cells

描述（由申请人提供）：本项目的目标是阐明有助于肺癌发生和维持的蛋白激酶C（PKC）信号传导机制，并将这些机制见解转化为更好的预后和治疗策略。我们最近发现了非典型的蛋白激酶C？PRKCI基因是人类肺中的致癌基因。此外，我们发现，小鼠PKC？基因Prkci是体内致癌Kras诱导的肺肿瘤发生的最早阶段所必需的。具体而言，Prkci是Kras介导的支气管肺泡干细胞（BASC）转化所必需的，BASC是Kras介导的肺肿瘤发生的假定起源细胞。Prkci的遗传破坏，或用PKC 9抑制剂金硫代苹果酸盐（ATM）治疗，在体外和体内阻断Kras介导的BASC的扩增和形态转化，以及在体内阻断肺肿瘤生长。初步结果表明，Kras，Prkci介导的BASCs扩增涉及polycomb基因Bmi 1的诱导。Bmi 1是一种与癌症干细胞身份和自我更新有关的表观遗传染色质修饰剂/转录调节因子。与Prkci一样，Bmi 1对于Kras介导的BASC扩增和肺肿瘤发生是必需的。基于这些初步数据，我们假设Prkci驱动Kras介导的BASC转化和肺肿瘤发生，至少部分是通过激活Bmi 1信号通路。我们进一步假设，类似的PKC？- Bmi 1信号轴在人肺癌干细胞的维持、扩增和致瘤潜能中起着关键作用。最后，我们假设ATM将有效地抑制人肺癌干细胞的自我更新和致瘤潜力。我们将通过完成两个相互关联的具体目标来检验这些假设。在目标1中，我们将评估PKC？Par 6-Ect 2-Rac 1信号转导轴在BASC转化中的作用，并分析了PKC？和Bmi 1信号。在目标2，我们将确定PKC的作用？和Bmi 1信号在肺癌干细胞的自我更新和肿瘤起始活性中的作用。我们将从原发性肺肿瘤中开发并鉴定一组肺癌干细胞系。这些研究的完成将提供重要的新的致癌PKC机制的见解？在假定的肺癌干细胞中的信号传导，增强我们对Kras介导的肺肿瘤发生的理解，并评估靶向肺癌干细胞中关键致癌途径的新型治疗剂的功效。这些研究对PKC？作为治疗靶点，以及ATM作为治疗肺癌的新治疗剂的用途。 公共卫生相关性：肺癌是美国癌症死亡的头号原因。蛋白激酶C？？(PKC?)是肺癌的癌基因、预后标志物和治疗靶点。该项目将阐明PKC？驱动肺癌干细胞生长和肿瘤启动活性的信号传导机制，并确定一种新型PKC的疗效？抑制剂，aurothiomalate，阻断肺癌干细胞生长和致瘤性。最后，该项目将从人类肺癌患者中产生新的肺癌干细胞资源。这些组织资源在评估针对这些致命细胞的新疗法方面将是非常宝贵的。

DESCRIPTION (provided by applicant): The goals of this project are to elucidate protein kinase C (PKC) signaling mechanisms that contribute to lung cancer initiation and maintenance and translate these mechanistic insights into better prognostic and treatment strategies. We recently identified the atypical PKC? gene PRKCI as a human oncogene in the lung. Furthermore, we find that the mouse PKC? gene Prkci is required for the very earliest steps of lung tumorigenesis induced by oncogenic Kras in vivo. Specifically, Prkci is necessary for Kras-mediated transformation of bronchio-alveolar stem cells (BASCs), the putative cell of origin of Kras-mediated lung tumorigenesis. Genetic disruption of Prkci, or treatment with the PKC9 inhibitor aurothiomalate (ATM), blocks Kras-mediated expansion and morphological transformation of BASC in vitro and in vivo, and lung tumor growth in vivo. Preliminary results suggest that Kras-, Prkci-mediated expansion of BASCs involves induction of the polycomb gene Bmi1. Bmi1 is an epigenetic chromatin modifier/transcriptional regulator implicated in cancer stem cell identity and self-renewal. Like Prkci, Bmi1 is necessary for Kras-mediated BASC expansion and lung tumorigenesis. Based on these preliminary data, we hypothesize that Prkci drives Kras-mediated BASC transformation and lung tumorigenesis, at least in part, through activation of the Bmi1 signaling pathway. We further hypothesize that a similar PKC?-Bmi1 signaling axis plays a critical role in the maintenance, expansion and tumorigenic potential of human lung cancer stem cells. Finally, we hypothesize that ATM will effectively inhibit the self-renewal and tumorigenic potential of human lung cancer stem cells. We will test these hypotheses through completion of two interrelated specific aims. In Aim 1 we will assess the role of the PKC?-Par6-Ect2-Rac1 signaling axis in BASC transformation and dissect the mechanism of crosstalk between PKC? and Bmi1 signaling in these cells. In Aim 2 we will determine the role of PKC? and Bmi1 signaling in the self-renewal and tumor initiating activity of lung cancer stem cells. We will develop and characterize a panel of lung cancer stem cell lines from primary lung tumors. Completion of these studies will provide important new mechanistic insight into oncogenic PKC? signaling in putative lung cancer stem cells, enhance our understanding of Kras-mediated lung tumorigenesis, and assess the efficacy of a novel therapeutic agent that targets a critical oncogenic pathway in lung cancer stem cells. These studies have important implications for PKC? as a therapeutic target and for the use of ATM as a novel therapeutic for the treatment of lung cancer. PUBLIC HEALTH RELEVANCE: Lung cancer is the number one cause of cancer death in the United States. Protein kinase C??(PKC?) is an oncogene, prognostic marker and therapeutic target in lung cancer. This project will elucidate PKC? signaling mechanisms that drive lung cancer stem cell growth and tumor-initiating activity, and determine the efficacy of a novel PKC? inhibitor, aurothiomalate, to block lung cancer stem cell growth and tumorigenicity. Finally, this project will generate novel lung cancer stem cell resources from human lung cancer patients. These tissue resources will be invaluable in the assessment of novel therapeutics targeting these deadly cells.