Protein Kinase C Signaling Mechanisms in Cancer

项目摘要 我们的长期目标是确定蛋白激酶C(PKC)的信号机制，这些信号机制有助于癌症和 将这些机械性的见解转化为更好的预后和治疗干预策略。在以前的 资助期：1)非典型pkc同工酶pkcι在非小细胞肺癌中是癌基因 (非小细胞肺癌)，美国癌症死亡的主要原因；2)建立了PKCι执行高度侵略性的 两种主要非小细胞肺癌亚型肺腺癌和肺的肿瘤起始细胞(TIC)表型 鳞状细胞癌；以及3)发现了一种具有临床应用前景的小分子蛋白激酶Cι抑制物 用于肺癌和卵巢癌的治疗。在当前的资助期内，我们表明：1)PKCι推动了 直接磷酸化并调节喉癌基因Sox2转录活性的喉癌TIC表型 谱系特异性多能干细胞因子；2)PKCι通过磷酸化建立LADC TIC表型 3)pkcι直接磷酸化并激活Rho 家族GTP酶ECT2调节其致癌活性；4)ECT2通过以下途径调节核糖体DNA转录 结合主要的rDNA转录因子上游结合因子1(Ubf1)，并招募rac1和Npm RDNA驱动体内转化生长和肺癌的形成；5)PKCι介导的ect2磷酸化 是ECT2驱动的rDNA转录所必需的。我们的初步研究表明：1)PKCι磷酸化 2)PKCι介导的Sox2 磷酸化调节Sox2与喉癌转化相关的直接转录靶点的结合；3) PKcι和ect2在SOX2依赖的喉癌遗传易感性小鼠模型中过度表达 忠实地概括了人类LSCC的许多方面。基于这些数据，我们假设：1)PKCι 通过磷酸化调节Ubf1、Ect2依赖的rRNA转录和LSCC转化 Ubf1-ECC2相互作用的依赖性调节；2)PKCι介导的Sox2磷酸化调控Sox2 LSCC TICS的转录编程；3)Sox2驱动的小鼠LSCC需要PrkCi和Ect2 体内的肿瘤发生。这些假设将通过完成设计的三个相互关联的具体目标来检验 目的：1)确定PKCι调控喉鳞状细胞癌细胞核糖体转录的机制；2) 鉴定并鉴定参与喉癌发生的直接蛋白激酶Cι-Sox2转录靶点； 3)确定PKC、ι和ECT2在SOX2依赖的喉癌体内发生中的作用。成功 这些目标的完成将为三个癌基因如何协调提供重要的新见解 在绝大多数人喉鳞状细胞中扩增和过表达，PRKCI，ECT2和SOX2，协同作用 推动喉癌的发生。通过这些研究获得的机械洞察力将提供新的治疗方法 改善喉癌治疗的机会。主要调查结果的翻译将由我们正在进行的 蛋白激酶Cι抑制剂金诺芬的临床研究进展

Project Abstract Our long-term goal is to identify protein kinase C (PKC) signaling mechanisms that contribute to cancer and translate these mechanistic insights into better prognostic and therapeutic intervention strategies. In previous funding periods, we: 1) identified atypical PKC isozyme PKCι as an oncogene in non-small cell lung cancer (NSCLC), the leading cause of cancer death in the U.S.; 2) established that PKCι enforces a highly aggressive tumor-initiating cell (TIC) phenotype in two major NSCLC subtypes, lung adenocarcinoma (LADC) and lung squamous cell carcinoma (LSCC); and 3) identified a small molecule PKCι inhibitor that shows clinical promise for lung and ovarian cancer treatment. During the current funding period we showed that: 1) PKCι drives a LSCC TIC phenotype by directly phosphorylating and regulating the transcriptional activity of Sox2, a LSCC lineage-specific pluripotent stem cell factor; 2) PKCι establishes a LADC TIC phenotype by phosphorylating and regulating Elf3, a key transcription factor in LADC; 3) PKCι directly phosphorylates and activates the Rho family GTPase GEF Ect2 to regulate its oncogenic activity; 4) Ect2 regulates ribosomal DNA transcription by binding the Upstream binding factor 1 (Ubf1), a major rDNA transcription factor, and recruiting Rac1 and Npm to rDNA to drive transformed growth and lung tumor formation in vivo; 5) PKCι-mediated Ect2 phosphorylation is required for Ect2-driven rDNA transcription. Our preliminary studies indicate that: 1) PKCι phosphorylates Ubf1 at a unique site required for Ect2 binding and rDNA transcription; 2) PKCι-mediated Sox2 phosphorylation regulates Sox2 binding to direct transcriptional targets implicated in LSCC transformation; 3) PKCι and Ect2 are overexpressed in a genetically-tractable mouse model of Sox2-dependent LSCC that faithfully recapitulates many aspects of human LSCC. Based on these data, we hypothesize that: 1) PKCι regulates Ubf1-, Ect2-dependent rRNA transcription and LSCC transformation through phosphorylation- dependent regulation of Ubf1-Ect2 binding interactions; 2) PKCι-mediated Sox2 phosphorylation controls Sox2 transcriptional programming of LSCC TICs; and 3) Prkci and Ect2 are required for Sox2-driven mouse LSCC tumorigenesis in vivo. These hypotheses will be tested by completing three interrelated specific aims designed to: 1) determine the mechanism by which PKCι regulates ribosomal RNA transcription in LSCC cells; 2) identify and functionally characterize direct PKCι-Sox2 transcriptional targets involved in LSCC tumorigenesis; and 3) determine the role of PKCι and Ect2 in Sox2-dependent LSCC tumorigenesis in vivo. Successful completion of these aims will provide significant new insight into how three oncogenes that are coordinately amplified and overexpressed in the vast majority of human LSCCs, PRKCI, ECT2 and SOX2, cooperate to drive LSCC tumorigenesis. Mechanistic insights gained through these studies will provide new therapeutic opportunities to improve treatment of LSCC. Translation of key findings will be facilitated by our ongoing clinical development of the PKCι inhibitor Auranofin.