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）：在检查有效的新型高亲和力PPAR3激动剂RS5444作为候选癌症治疗时，我们发现RS5444与观察到的抗肿瘤效应一起，将RHOB mRNA和蛋白质迅速上调。这促使我们研究了以下新的假设，即下游RHOB的作用部分介导了PPAR3对癌症发病机理的贡献。 RHOB是一个小的GTPase调节肌动蛋白组织，囊泡转运未在癌症中突变。但是，RHOB抑制了增殖。我们先前已经显示了RS5444，并且可以在体外和体内结合紫杉醇在甲状腺甲状腺癌（ATC）模型中协同组合，并且Cyclin激酶抑制剂P21WAF1/CIP1（P21）是PPAR3介导的生长抑制作用所必需的。我们现在报告说，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，沉默的RHOB导致5444卢比的生长抑制活性损失，加强了我们的假设，并导致我们首次证明RHOB上调导致ATC中的癌细胞死亡。这些数据以及我们档案ATC组织中RHOB下调的初步数据使我们假设RHOB在ATC和ATC发病机理的化学敏感性中很重要。基于这些发现，将1/2阶段的临床试验结合起来，将RS5444和紫杉醇合并为ATC，以改善紫杉醇3在这种几乎统一致命的癌症中的单一药物效应。随着早期反应与患者结局的相关，与该试验结合使用的肿瘤活检将允许测量RHOB和P21诱导。仅RS5444在ATC中诱导G0/G1细胞周期停滞而没有凋亡，而强迫表达RHOB（TET RHOB）则足以诱导P21，G2/M停滞和凋亡。这些观察结果以及另一个发现，RHOB错误地与细胞核差异，在核复合物中与p21共定位，其中包括蛋白激酶C相关的激酶One（PRK1），一种已知的RHOB相互作用的蛋白质和丝氨酸/三氨酸激酶。这种复合物是由RS5444产生的，并且强迫RHOB表达导致我们假设这种新型的核复合物通过与细胞周期机械复合物直接相互作用以及P21的翻译后修饰导致其物理与G0/G1/G1/G2/M细胞周期的物理缔合在此直接相互作用。在AIM 1中，我们将详细说明RHOB通过这种新型核复合物介导细胞周期停滞和凋亡的机制。在AIM 2中，RHOB在凋亡和抗肿瘤协同作用中的作用将在动物模型中定义，并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AIM 3中，我们将制定预后指标以应对治疗。我们的数据表明RHOB是一种新型分子开关，指示细胞命运。因此，拟议的研究不仅具有提高对RHOB信号传导的理解的潜力，而且最终导致ATC的治疗方法改善。 公共卫生相关性：RHOB是一个小的GTPase，已被发现是一种新型抗肿瘤信号通路中的关键联系。使用新型的ppargamma激动剂与紫杉醇结合使用，这对于组合治疗抗肿瘤协同作用至关重要。现在，我们建议扩展研究，以更充分地阐明Rho B对组合疗法中Rho B对细胞增殖和细胞死亡的影响，抗肿瘤协同作用的影响，并检查在1/2阶段ATC临床试验中对治疗反应的分子相关性。