RhoB in cancer pathogenesis and as a target in combinatorial therapy

RhoB 在癌症发病机制中的作用及其作为组合治疗的靶点

• 批准号: 7889545
• 负责人: John A. Copland
• 金额: $ 33.58万
• 依托单位: MAYO CLINIC JACKSONVILLE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7889545
• 关键词: Actins; Affinity; Agonist; Animal Model; Antineoplastic Agents; Apoptosis; Apoptotic; Binding; Biological Markers; Biopsy; Cancer Model; Cancer cell line; Cell Cycle; Cell Cycle Arrest; Cell Death; Cell Nucleus; Cell Proliferation; Cells; Clinical Trials; Combined Modality Therapy; Complex; Coupled; Cyclin-Dependent Kinase Inhibitor; Cyclin-Dependent Kinases; Cyclins; DNA Damage; Data; Down-Regulation; Drug resistance; Event; G2/M Arrest; Growth; Histone Deacetylase Inhibitor; Human; In Vitro; Laboratories; Lead; Link; M cell; Malignant Neoplasms; Malignant neoplasm of thyroid; Measurement; Mediating; Messenger RNA; Mitosis; Modification; Molecular; Molecular Models; Molecular Target; Monomeric GTP-Binding Proteins; Mutate; Normal tissue morphology; Nuclear; Outcome; PDPK1 gene; PPAR gamma; Paclitaxel; Pathogenesis; Patients; Pharmaceutical Preparations; Phase; Phosphatidylinositols; Phosphorylation; Phosphotransferases; Post-Translational Protein Processing; Protein Kinase C; Protein-Protein Interaction Map; Protein-Serine-Threonine Kinases; Proteins; Proto-Oncogene Proteins c-akt; Reporting; Resistance; Role; Serine; Signal Pathway; Signal Transduction; Specific qualifier value; Testing; Tetanus Helper Peptide; Tetracyclines; Therapeutic; Threonine; Thyroid Gland; Time; Tissues; Transport Vesicles; Tumor-Derived; Up-Regulation; angiogenesis; base; cancer cell; caspase-3; cell transformation; chemotherapy; combinatorial; cytotoxic; evidence base; human PIK3CA protein; improved; in vivo; in vivo Model; mTOR Signaling Pathway; molecular modeling; novel; oncology; oncoprotein p21; patient population; prognostic indicator; protein complex; protein expression; public health relevance; response; rho; tumor

DESCRIPTION (Provided By Applicant): In examining the potent novel high affinity PPAR3 agonist, RS5444, as a candidate cancer therapeutic, we discovered that RhoB mRNA and protein were rapidly upregulated by RS5444 in concert with observed antineoplastic effects. This prompted us to examine the novel hypothesis that downstream RhoB effects in part mediate the contributions of PPAR3 to cancer pathogenesis. RhoB is a small GTPase regulating actin organization and vesicle transport not mutated in cancer. RhoB, however, inhibits proliferation. We had previously showed RS5444 and paclitaxel can be combined synergistically in anaplastic thyroid cancer (ATC) models in vitro and in vivo and that the cyclin kinase inhibitor, p21WAF1/CIP1 (p21), is necessary for PPAR3- mediated growth inhibition and for the apoptotic synergy induced by the combination. We now report that RhoB is critical for RS5444/PPAR3-mediated p21 mRNA and protein induction. Silencing RhoB in our laboratory resulted in loss of growth inhibitory activity by RS5444, bolstering our hypothesis, and leading us to demonstrate for the first time that forced RhoB upregulation leads to cancer cell death in ATC. These data, coupled with preliminary data of RhoB down-regulation in our archival ATC tissues, led us to hypothesize that RhoB is important in the chemosensitivity of ATC and in ATC pathogenesis. Based upon these findings, a Phase 1/2 clinical trial combining RS5444 and paclitaxel is under way in ATC in efforts to improve the single agent effects of paclitaxel 3 in this nearly uniformly fatal cancer. Tumor biopsies obtained in conjunction with this trial will allow measurement of RhoB and p21 induction as early response correlates to patient outcome. RS5444 alone induces G0/G1 cell cycle arrest without apoptosis in ATC and forced expression of RhoB (Tet RhoB) proves sufficient for induction of p21, G2/M arrest and apoptosis. These observations coupled with another discovery that RhoB mislocalizes to the nucleus, colocalizing with p21 in a nuclear complex that includes protein kinase C-related kinase one (PRK1), a known RhoB interacting protein and serine/threonine kinase. This complex forms as a result of RS5444 as well as forced RhoB expression leading us to hypothesize that this novel nuclear complex mediates RhoB antitumor activity via direct interaction with cell cycle machinery complexes and that post-translational modifications of p21 direct its physical association with either G0/G1 or G2/M cell cycle machinery thereby specifying cell cycle arrest or apoptosis. In Aim 1, we will elaborate the mechanism(s) by which RhoB mediates cell cycle arrest and apoptosis via this novel nuclear complex. In Aim 2, the role of RhoB in apoptotic and antitumor synergy will be defined in animal models as well as using other newly discovered drugs upregulating RhoB that may be useful for patients with PPAR3- negative ATC. In Aim 3, we will develop prognostic indicators for response to therapy. Our data indicate RhoB as a novel molecular switch dictating cell fate. Thusly, proposed studies have potential not only to improve understanding of RhoB signaling, but to ultimately lead to improved therapeutic approaches in ATC. PUBLIC HEALTH RELEVANCE: RhoB, a small GTPase, has been discovered as a critical link in a novel antitumor signaling pathway. It is critical for combinatorial therapy antitumor synergy using a novel PPARgamma agonist combined with paclitaxel. We now propose to extend our studies to more fully elucidate the mechanisms underlying the effects of Rho B on cell proliferation and cell death, antitumor synergy in combination therapy, and examine molecular correlates for response to therapy in a Phase 1/2 ATC clinical trial.

描述（由申请人提供）：在检查作为候选癌症治疗剂的有效新型高亲和力 PPAR3 激动剂 RS5444 时，我们发现 RhoB mRNA 和蛋白质被 RS5444 快速上调，与观察到的抗肿瘤作用一致。这促使我们检验新的假设，即下游 RhoB 效应在一定程度上介导 PPAR3 对癌症发病机制的贡献。 RhoB 是一种小型 GTP 酶，调节肌动蛋白组织和囊泡运输，在癌症中未发生突变。然而，RhoB 抑制增殖。我们之前已经证明，RS5444 和紫杉醇可以在体外和体内的未变性甲状腺癌 (ATC) 模型中协同组合，并且细胞周期蛋白激酶抑制剂 p21WAF1/CIP1 (p21) 对于 PPAR3 介导的生长抑制和组合诱导的细胞凋亡协同作用是必需的。我们现在报道 RhoB 对于 RS5444/PPAR3 介导的 p21 mRNA 和蛋白质诱导至关重要。在我们的实验室中沉默 RhoB 会导致 RS5444 失去生长抑制活性，这支持了我们的假设，并使我们首次证明强制 RhoB 上调会导致 ATC 中的癌细胞死亡。这些数据，加上我们存档的 ATC 组织中 RhoB 下调的初步数据，使我们推测 RhoB 在 ATC 的化学敏感性和 ATC 发病机制中很重要。基于这些发现，ATC 正在进行一项结合 RS5444 和紫杉醇的 1/2 期临床试验，以努力改善紫杉醇 3 在这种几乎一致致命的癌症中的单药疗效。与该试验一起获得的肿瘤活检将允许测量 RhoB 和 p21 诱导，因为早期反应与患者结果相关。 RS5444 单独诱导 ATC 中 G0/G1 细胞周期停滞而不发生细胞凋亡，并且 RhoB (Tet RhoB) 的强制表达证明足以诱导 p21、G2/M 停滞和细胞凋亡。这些观察结果与另一项发现相结合，即 RhoB 错误定位到细胞核，与 p21 共定位于核复合物中，该核复合物包括蛋白激酶 C 相关激酶一 (PRK1)、一种已知的 RhoB 相互作用蛋白和丝氨酸/苏氨酸激酶。该复合物是 RS5444 以及强制 RhoB 表达的结果，使我们推测这种新型核复合物通过与细胞周期机械复合物直接相互作用介导 RhoB 抗肿瘤活性，并且 p21 的翻译后修饰指导其与 G0/G1 或 G2/M 细胞周期机械的物理关联，从而指定细胞周期停滞或凋亡。在目标 1 中，我们将详细阐述 RhoB 通过这种新型核复合物介导细胞周期停滞和细胞凋亡的机制。在目标 2 中，将在动物模型中定义 RhoB 在细胞凋亡和抗肿瘤协同作用中的作用，以及使用其他新发现的上调 RhoB 的药物，这些药物可能对 PPAR3 阴性 ATC 患者有用。在目标 3 中，我们将制定治疗反应的预后指标。我们的数据表明 RhoB 是一种决定细胞命运的新型分子开关。因此，拟议的研究不仅有可能提高对 RhoB 信号传导的理解，而且最终有可能改进 ATC 的治疗方法。 公共健康相关性：RhoB 是一种小型 GTP 酶，已被发现是新型抗肿瘤信号通路中的关键环节。使用新型 PPARγ 激动剂与紫杉醇联合进行联合治疗抗肿瘤协同作用至关重要。我们现在建议扩展我们的研究，以更全面地阐明 Rho B 对细胞增殖和细胞死亡的影响机制、联合治疗中的抗肿瘤协同作用，并在 1/2 期 ATC 临床试验中检查治疗反应的分子相关性。