Rap1Gap and Tumor Progression

Rap1Gap 和肿瘤进展

• 批准号: 7866633
• 负责人: JUDY L MEINKOTH
• 金额: $ 33.18万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7866633
• 关键词: Adherent Culture; Angioinvasion; Attenuated; Cell Line; Cell physiology; Cell-Cell Adhesion; Cells; Cellular Structures; Clinical; Complement; Data; Defect; Disease; Dissociation; Down-Regulation; E-Cadherin; Employee Strikes; Environment; Epithelial; Exhibits; Genes; Guanosine Triphosphate Phosphohydrolases; Human; In Vitro; Intercellular Junctions; Maintenance; Malignant Epithelial Cell; Malignant Neoplasms; Malignant neoplasm of thyroid; Molecular; Morphology; Neoplasm Metastasis; Outcome; Papillary thyroid carcinoma; Pathogenesis; Primary Neoplasm; Property; Rattus; Regulation; Role; Sampling; Signal Transduction; Specimen; Structure; Testing; Thyroid Gland; Thyroid carcinoma; Tumor Cell Line; Vimentin; base; cell motility; clinically significant; epithelial to mesenchymal transition; human tissue; lymph nodes; matrigel; neoplastic cell; outcome forecast; public health relevance; research study; thyroid neoplasm; tumor; tumor progression

DESCRIPTION (provided by applicant): One of the most critical steps in the progression to malignancy is the acquisition by tumor cells of the ability to metastasize. The hypothesis to be tested in this proposal is that downregulation of Rap1GAP contributes to thyroid tumor progression. This notion is based on data showing that Rap1GAP is highly expressed in normal human thyroid cells, and that its expression is dramatically reduced in the majority of invasive papillary thyroid carcinomas. Studies in human thyroid carcinoma cell lines revealed a striking correlation between loss of Rap1GAP and loss of epithelial structure. Rap1GAP-deficient tumor cells lacked E-cadherin and acquired the expression of vimentin, indicative of epithelial-to-mesenchymal transition. These cells exhibited enhanced migratory and invasive properties compared to tumor cells that retained Rap1GAP. Restoring Rap1GAP to Rap1GAP-deficient cells inhibited cell migration, invasion and anchorage-independent proliferation. Silencing Rap1GAP expression in thyroid carcinoma cells that retain an epithelial morphology caused the cells to disperse, enhanced the dissociation of cell aggregates, and dysregulated E-cadherin, suggestive of defects in cell/cell adhesion. As disruption of cell/cell junctions is associated with serious pathological consequences, we propose that downregulation of Rap1GAP contributes to the pathogenesis of thyroid tumors by attenuating cell/cell adhesion. In vitro studies will explore the molecular mechanism through which decreased Rap1GAP expression attenuates cell/cell adhesion and assess whether eliminating Rap1GAP endows tumor cells with altered migratory properties and invasive potential. As TSH regulation of Rap1GAP is lost from the human thyroid tumor cell lines, but is likely to be retained in primary thyroid tumors, complementary studies will be performed in differentiated rat thyroid cells. These studies will be conducted in cells in three-dimensional environments, conditions that more closely reproduce the matrix compliance of human tissues and where cell/cell contacts are maximized. The in vitro studies are complemented with studies in human tumor specimens that will identify the subtypes of thyroid tumors in which Rap1GAP expression is decreased and probe the clinical significance of loss of Rap1GAP. In summary, this proposal presents a highly cohesive plan to investigate the contribution and clinical significance of Rap1GAP depletion to the progression of human thyroid tumors. PUBLIC HEALTH RELEVANCE: This proposal investigates the contribution and clinical significance of decreased Rap1GAP expression to the progression of human thyroid tumors. Studies in human thyroid tumor cell lines will elucidate the mechanism through which downregulation of Rap1GAP attenuates cell/cell adhesion and investigate whether loss of Rap1GAP enhances migratory and invasive potential. Studies in human tumor specimens will identify the subtypes of thyroid tumors that exhibit Rap1GAP downregulation, assess whether decreased expression of Rap1GAP is correlated with the presence of metastatic disease at presentation, examine whether Rap1GAP expression is further decreased in lymph node metastases compared to primary tumors and assess whether Rap1GAP expression is correlated with the presence of angioinvasion or lymphoinvasion, markers of poor prognosis.

描述（由申请人提供）：恶性肿瘤进展的最关键步骤之一是肿瘤细胞获得转移能力。本研究拟验证的假设是Rap1GAP下调有助于甲状腺肿瘤的进展。这一观点是基于Rap1GAP在正常人甲状腺细胞中高表达的数据，而在大多数浸润性甲状腺乳头状癌中其表达显著降低。对人甲状腺癌细胞系的研究表明，Rap1GAP的缺失与上皮结构的缺失之间存在显著的相关性。rap1gap缺陷的肿瘤细胞缺乏E-cadherin，获得了vimentin的表达，表明了上皮细胞向间质细胞的转变。与保留Rap1GAP的肿瘤细胞相比，这些细胞表现出增强的迁移和侵袭特性。在Rap1GAP缺失的细胞中恢复Rap1GAP可抑制细胞迁移、侵袭和不依赖锚定的增殖。在保留上皮形态的甲状腺癌细胞中，沉默Rap1GAP表达会导致细胞分散，增强细胞聚集体的解离，并导致e -钙粘蛋白失调，提示细胞/细胞粘附缺陷。由于细胞/细胞连接的破坏与严重的病理后果相关，我们提出下调Rap1GAP通过减弱细胞/细胞粘附参与甲状腺肿瘤的发病机制。体外研究将探索Rap1GAP表达降低细胞/细胞粘附的分子机制，并评估消除Rap1GAP是否会改变肿瘤细胞的迁移特性和侵袭潜力。由于TSH对Rap1GAP的调节在人甲状腺肿瘤细胞系中缺失，但在原发性甲状腺肿瘤中可能保留，因此将在分化的大鼠甲状腺细胞中进行补充研究。这些研究将在三维环境中的细胞中进行，这些条件更接近地再现了人体组织的基质顺应性，并且细胞/细胞接触最大化。在体外研究的基础上，辅以人肿瘤标本研究，确定Rap1GAP表达降低的甲状腺肿瘤亚型，探讨Rap1GAP缺失的临床意义。总之，本提案提出了一个高度连贯的计划来研究Rap1GAP缺失对人类甲状腺肿瘤进展的贡献和临床意义。公共卫生相关性：本研究旨在探讨Rap1GAP表达降低对人甲状腺肿瘤进展的影响及其临床意义。对人甲状腺肿瘤细胞系的研究将阐明下调Rap1GAP降低细胞/细胞粘附的机制，并探讨Rap1GAP缺失是否会增强迁移和侵袭潜能。对人类肿瘤标本的研究将确定表现出Rap1GAP下调的甲状腺肿瘤亚型，评估Rap1GAP表达降低是否与出现转移性疾病相关，检查与原发肿瘤相比，淋巴结转移中Rap1GAP表达是否进一步降低，评估Rap1GAP表达是否与存在血管侵袭或淋巴侵袭相关，这些都是预后不良的标志。