cGMP Phosphodiesterase, a Novel Chemoprevention Target

cGMP 磷酸二酯酶，一种新型化学预防靶点

• 批准号: 6783821
• 负责人: Gary A Piazza
• 金额: $ 11.43万
• 依托单位: SOUTHERN RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6783821
• 关键词: antineoplastics; apoptosis; biomarker; cGMP dependent protein kinase; cadherins; cancer prevention; carcinogenesis; cell line; chemoprevention; colon neoplasms; cyclic GMP; drug design /synthesis /production; enzyme activity; enzyme inhibitors; gene mutation; genetically modified animals; isozymes; laboratory mouse; neoplasm /cancer pharmacology; neoplastic cell; nonsteroidal antiinflammatory agent; pharmacokinetics; phosphodiesterases; prostaglandin endoperoxide synthase; protein degradation

DESCRIPTION (provided by applicant): The overall objective of this proposal is to validate cyclic GMP phosphodiesterase (cGMP PDE) as a novel drug target for cancer chemoprevention. Previous studies have suggested that the chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) involve a cyclooxygenase (COX)-dependent and independent mechanism of action, although the precise target(s) and pathways responsible for their apoptosis inducing activity have not been well defined. In support of a COX-independent mechanism, structurally related drugs such as sulindac sulfone have been shown to have broad chemopreventive efficacy in clinical and preclinical studies without inhibiting COX-1 or -2 isozymes. Moreover, high dosages of NSAIDs and COX-2 inhibitors appear to be required for chemopreventive efficacy relative to their anti-inflammatory activity. The possibility of disassociating COX inhibitory activity from their antineoplastic activity has significant implications for developing safer and more efficacious drugs given that the chemopreventive efficacy of NSAIDs, including COX-2 selective inhibitors, is limited by COX-dependent toxicity. Recently, sulindac sulfone was reported to inhibit cGMP PDE and elevate intracellular cGMP levels to activate protein kinase G (PKG). This pathway has been linked to apoptosis induction by a novel mechanism involving PKG-mediated phosphorylation and degradation of beta-catenin to inhibit Tcf-dependent transcription of cell survival genes. We hypothesize that the chemopreventive activity of certain NSAIDs and COX-2 selective inhibitors is also mediated by cGMP PDE inhibition which may provide a highly selective mechanism for inducing apoptosis of neoplastic cells that harbor Apc or beta-catenin mutations. The proposed studies will focus on colon carcinogenesis that involves Apc gene mutations and can be inhibited by NSAIDs in a COX-independent manner. In vitro and in vivo studies are proposed to determine if cGMP PDE is responsible for the chemopreventive efficacy of NSAIDs and COX-2 inhibitors. Initial studies will determine if the growth inhibitory and apoptosis inducing activity of a panel of structurally diverse NSAIDs and COX-2 selective inhibitors correlate with cGMP PDE inhibition and will be compared to inhibitory effects on cAMP PDE as well as COX-1 and COX-2. The effects of PDE inhibitory NSAIDs (PiNs) on intracellular cGMP and cAMP levels will be measured to study potential isozyme selectivity in intact colon tumor cells. The activation of PKG and potential effects on PKA as well as a downstream pathway involving beta-catenin degradation and inhibition of Tcf-dependent transcription will be investigated. In vivo studies in the ApcMin mouse model of colon tumorigenesis will be performed to compare the efficacy of a PIN and a non-COX inhibitory cGMP PDE inhibitor. Finally, cGMP and cAMP levels will be measured in tumors and plasma samples from this study to determine if PDE inhibition occurs in vivo and the utility of cyclic nucleotides as biomarkers.

描述（由申请人提供）： 该提案的总体目标是验证环 GMP 磷酸二酯酶 (cGMP PDE) 作为癌症化学预防的新型药物靶点。先前的研究表明，非甾体抗炎药（NSAID）的化学预防功效涉及环氧合酶（COX）依赖性和独立的作用机制，尽管其细胞凋亡诱导活性的精确靶点和途径尚未明确。为了支持 COX 独立机制，结构相关的药物（如舒林酸砜）已在临床和临床前研究中显示出广泛的化学预防功效，且不抑制 COX-1 或 -2 同工酶。此外，相对于其抗炎活性，似乎需要高剂量的 NSAID 和 COX-2 抑制剂才能发挥化学预防功效。鉴于包括 COX-2 选择性抑制剂在内的 NSAID 的化学预防功效受到 COX 依赖性毒性的限制，将 COX 抑制活性与其抗肿瘤活性分开的可能性对于开发更安全、更有效的药物具有重要意义。最近，据报道，舒林酸砜可抑制 cGMP PDE 并提高细胞内 cGMP 水平，从而激活蛋白激酶 G (PKG)。该途径通过一种新机制与细胞凋亡诱导相关，该机制涉及 PKG 介导的磷酸化和 β-catenin 降解，从而抑制细胞存活基因的 Tcf 依赖性转录。我们假设某些 NSAID 和 COX-2 选择性抑制剂的化学预防活性也是由 cGMP PDE 抑制介导的，这可能为诱导含有 Apc 或 β-catenin 突变的肿瘤细胞凋亡提供高度选择性的机制。拟议的研究将重点关注涉及 Apc 基因突变的结肠癌发生，并且可以通过非甾体抗炎药以不依赖于 COX 的方式抑制。建议进行体外和体内研究以确定 cGMP PDE 是否与 NSAID 和 COX-2 抑制剂的化学预防功效有关。初步研究将确定一组结构多样的 NSAID 和 COX-2 选择性抑制剂的生长抑制和细胞凋亡诱导活性是否与 cGMP PDE 抑制相关，并将与对 cAMP PDE 以及 COX-1 和 COX-2 的抑制作用进行比较。将测量 PDE 抑制性 NSAID (PiN) 对细胞内 cGMP 和 cAMP 水平的影响，以研究完整结肠肿瘤细胞中潜在的同工酶选择性。将研究 PKG 的激活和对 PKA 的潜在影响，以及涉及 β-catenin 降解和 Tcf 依赖性转录抑制的下游途径。将在结肠肿瘤发生的 ApcMin 小鼠模型中进行体内研究，以比较 PIN 和非 COX 抑制性 cGMP PDE 抑制剂的功效。最后，将测量本研究的肿瘤和血浆样本中的 cGMP 和 cAMP 水平，以确定体内是否发生 PDE 抑制以及环核苷酸作为生物标志物的效用。