Signaling of Integrin Alpha 7

整合素 Alpha 7 的信号转导

• 批准号: 8267061
• 负责人: JIANHUA LUO
• 金额: $ 25.55万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8267061
• 关键词: Amino Acid Motifs; Amino Acids; Anchorage-Independent Growth; Apoptosis; Binding; Biological; Biological Assay; Breast; Cell Death; Cell Death Induction; Cell Death Inhibition; Cell Differentiation process; Cell Line; Cells; Clinical; Cyclin-Dependent Kinase Inhibitor 3; Cytoskeleton; DU145; Data; Deceleration; Detection; Development; Diagnosis; Disease; Down-Regulation; Epithelial Cells; Event; Extracellular Matrix; Frequencies; Genes; Genome; Glioblastoma; Growth; Heterogeneity; ITGA7 gene; In Situ Nick-End Labeling; In Vitro; Indolent; Induction of Apoptosis; Integrins; Knock-out; Knockout Mice; Lead; Life; Link; Liver; Malignant Neoplasms; Malignant neoplasm of prostate; Mass Spectrum Analysis; Mediating; Meta-Analysis; Micro Array Data; Mouse Strains; Mus; Mutate; Mutation; Mutation Analysis; Neoplasm Metastasis; Organogenesis; Patients; Peptide Hydrolases; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Point Mutation; Primary carcinoma of the liver cells; Prostate; Prostate Adenocarcinoma; Prostate Leiomyosarcoma; Prostate-Specific Antigen; Prostatic Neoplasms; Protein-Serine-Threonine Kinases; Proteins; Publishing; Relapse; Respiratory Diaphragm; Role; Screening procedure; Serum; Signal Pathway; Signal Transduction; Small Interfering RNA; Staining method; Stains; Structural Protein; System; TdT-Mediated dUTP Nick End Labeling Assay; Testing; Tissues; Tumor Suppression; Tumor Suppressor Genes; Tumor Volume; Wound Healing; Xenograft procedure; annexin A5; base; cancer cell; caspase-3; cell growth; cell motility; clinically relevant; expression vector; human ITGA7 protein; integrin-linked kinase; knock-down; leiomyosarcoma; matrigel; migration; mortality; mouse model; mutant; myopodin; neoplastic cell; overexpression; programs; public health relevance; restoration; soft tissue; tumor growth; tumorigenesis; vector; yeast two hybrid system

DESCRIPTION (provided by applicant): Studies in liver and breast have indicated that extracellular matrix plays a critical role in limiting the growth and promoting the differentiation of epithelial cells. However, the signaling mechanism that leads to inhibition of over-growth of epithelial cells is not well understood. Recently, we performed a mutational analysis on ITGA7 gene (ITGA7). We found mutations on ITGA7 in prostate cancer, hepatocellular carcinoma, leiomyosarcoma and glioblastoma multiforms with frequencies ranging from 25% to 83%. Many of these mutations caused truncation, micro-deletion or frameshift of the protein. Interestingly, patients with ITGA7 mutations had higher rate of clinical relapse in both prostate cancer and hepatocellular carcinoma. Mouse model of PC3 and Du145 xenografted prostate tumors showed a dramatic reduction in tumor volume, rate of metastasis and rate of mortality when expression of ITGA7 was restored in these cell lines. ITGA7 induced the expression of cyclin dependent kinase inhibitor 3 (CDKN3) and RACGAP1. siRNA knocking down of CDKN3 and RACGAP1 completely reversed the growth inhibition effect of IGGA7, while only partially reversed the migration inhibition activity. Recently, Annexin V staining and TUNEL assays indicated that over-expression of ITGA7 induced apoptosis in PC3 cells. Through a Yeast two-hybrid system, we identified that the C-terminus of ITGA7 interacted with HtrA2, a cell death protein. A 30 amino acid motif located in the C-terminus of ITGA7 was identified as critical for its interaction with HtrA2. Expression of ITGA7 induced protease activity of HtrA2. siRNA knocking down of HtrA2 abolished the cell death induction by ITGA7. Separately, expression of ITGA7 induced the kinase activity of integrin link kinease (ILK). Interestingly, we also found that ILK, a serine/threonine kinase and structural protein associated with integrins and the cytoskeleton, bound and phosphorlyated a tumor suppressor gene called myopodin, which regulates cell growth and cell motility. Based on these preliminary data, we hypothesize that ITGA7 activates HtrA2 and ILK signaling pathways to achieve induction of apoptosis, cell growth inhibition and migration deceleration. In this study, we propose: 1) To elucidate the role of ITGA7/HtrA2 interaction in mediating cell death and inhibition of cancer invasion by analyzing the mutant ITGA7 molecule defective of binding with HtrA2 in PC3 and DU145 cells; 2) To investigate the role of ILK/myopodin interaction in ITGA7 regulated cell motility, cell growth and inhibition of invasiveness by analyzing myopodin defective cell system; 3) To study the impact of ITGA7 knock-out on the carciongenesis of TRAMP mice, and to investigate the biological role of ITGA7 in prostate gland tissue development, cell differentiation and tumorigenesis in pure ITGA7 knockout mice. PUBLIC HEALTH RELEVANCE: The project is to investigate how integrin ?7 dictates cell growth, migration, cell death and invasiveness in prostate cancer, what role integrin ?7 plays in prostate gland organogenesis and prostate cancer development, and whether restoration of integrin ?7 expression has a role in suppressing metastasis for prostate cancer.

描述（申请人提供）：肝脏和乳腺研究表明，细胞外基质在限制上皮细胞生长和促进分化方面发挥着关键作用。然而，导致抑制上皮细胞过度生长的信号传导机制尚不清楚。最近，我们对ITGA7基因（ITGA7）进行了突变分析。我们在前列腺癌、肝细胞癌、平滑肌肉瘤和多形性胶质母细胞瘤中发现 ITGA7 突变，频率范围为 25% 至 83%。许多突变导致蛋白质截短、微缺失或移码。有趣的是，ITGA7突变患者的前列腺癌和肝细胞癌临床复发率较高。 PC3 和 Du145 异种移植前列腺肿瘤的小鼠模型显示，当这些细胞系中恢复 ITGA7 的表达时，肿瘤体积、转移率和死亡率显着降低。 ITGA7 诱导细胞周期蛋白依赖性激酶抑制剂 3 (CDKN3) 和 RACGAP1 的表达。 siRNA敲低CDKN3和RACGAP1完全逆转了IGGA7的生长抑制作用，而仅部分逆转了迁移抑制活性。最近，Annexin V 染色和 TUNEL 检测表明 ITGA7 的过度表达诱导 PC3 细胞凋亡。通过酵母双杂交系统，我们发现 ITGA7 的 C 末端与细胞死亡蛋白 HtrA2 相互作用。位于 ITGA7 C 末端的 30 个氨基酸基序被确定为其与 HtrA2 相互作用的关键。 ITGA7 的表达诱导 HtrA2 的蛋白酶活性。 siRNA 敲低 HtrA2 消除了 ITGA7 诱导的细胞死亡。另外，ITGA7 的表达诱导整合素连接激酶 (ILK) 的激酶活性。有趣的是，我们还发现ILK（一种丝氨酸/苏氨酸激酶和与整联蛋白和细胞骨架相关的结构蛋白）结合并磷酸化称为肌足蛋白（myopodin）的肿瘤抑制基因，该基因调节细胞生长和细胞运动。基于这些初步数据，我们假设ITGA7激活HtrA2和ILK信号通路以实现诱导细胞凋亡、抑制细胞生长和减缓迁移。在本研究中，我们建议：1）通过分析PC3和DU145细胞中与HtrA2结合缺陷的突变ITGA7分子，阐明ITGA7/HtrA2相互作用在介导细胞死亡和抑制癌症侵袭中的作用； 2）通过分析Myopodin缺陷细胞系统，探讨ILK/Myopodin相互作用在ITGA7调节细胞运动、细胞生长和抑制侵袭性中的作用； 3）研究ITGA7敲除对TRAMP小鼠致癌的影响，并探讨ITGA7在纯ITGA7敲除小鼠前列腺组织发育、细胞分化和肿瘤发生中的生物学作用。 公共健康相关性：该项目旨在研究整合素 ?7 如何决定前列腺癌中的细胞生长、迁移、细胞死亡和侵袭性，整合素 ?7 在前列腺器官发生和前列腺癌发展中发挥什么作用，以及整合素 ?7 表达的恢复是否在抑制前列腺癌转移中发挥作用。