Role of pRb in Osteogenesis, Cell Cycle Exit and Cancer

pRb 在成骨、细胞周期退出和癌症中的作用

• 批准号: 7213528
• 负责人: Philip W. Hinds
• 金额: $ 34.59万
• 依托单位: TUFTS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7213528
• 关键词: Abnormal Cell; Adherens Junction; Automobile Driving; Biochemical Pathway; Biological; Cell Aging; Cell Cycle; Cell Proliferation; Cell Shape; Cell division; Cell physiology; Cell surface; Cells; Cellular Stress; Cellular biology; Complex; Data; Development; ERM protein; Event; Gene Expression; Generic Drugs; Genes; Genomics; Growth; Human; In Vitro; Knock-out; Knowledge; Link; Longevity; Malignant Neoplasms; Mediating; Messenger RNA; Modification; Molecular; Mouse Strains; Mus; N-Cadherin; Osteoblasts; Osteogenesis; Pathway interactions; Pattern; Pediatric Neoplasm; Phenotype; Play; Primary Cell Cultures; Process; Property; Proteins; Proteomics; Range; Regulation; Research Personnel; Retinoblastoma; Retinoblastoma Protein; Role; Shapes; Staging; System; Therapeutic Intervention; Time; Tissues; Tumor Suppressor Proteins; Undifferentiated; Withdrawal; Work; bone; cancer cell; cdc Genes; cell type; density; design; ezrin; gene repression; in vivo; insight; knock-down; neoplastic cell; novel; osteosarcoma; p107 protein; prevent; programs; promoter; recombinase; research study; senescence; tumor; tumor growth; tumorigenesis; tumorigenic; vector

DESCRIPTION (provided by applicant): The relationships between differentiation, proliferation and senescence are fundamental to cell biology, recapitulated in multiple tissue systems. Molecules identified either as regulators of differentiation or of cellular proliferation have turned out to possess pleiotropic and often unexpected roles in other systems. For example, the retinoblastoma protein (pRb) was initially identified as a tumor suppressor protein and cell cycle regulator critical to the genesis of the childhood tumor, retinoblastoma, but has since been shown to play key roles both in cellular senescence and development in a wide range of cell types and associated tumors. Despite this clear association of pRb with tumor-suppressive mechanisms in most human tumors, a detailed understanding of pRb's role in these processes is lacking. We have found that aspects of the senescent state engendered by the pRb tumor suppressor depend on activation of cdk5 and modification and increased expression of ERM proteins. The experiments described below are designed to elucidate pRb's function in activation of cdk5 and to explore the consequences of this on senescent cell biology in the context of tumor growth. Intriguingly, our work on the role of pRb in differentiation of normal mouse osteoblasts both in vivo and in culture suggests that pRb may also work through cdk5 to influence the osteoblast's ability to sense cell-cell contact and undergo proliferative arrest. Further, we find that loss of pRb has multiple effects on gene expression patterns during osteoblast differentiation that result in accumulation of cells with apparent osteoprogenitor potential, thus likely predisposing osteoblasts to tumorigenic conversion. In order to understand the mechanisms involved in pRb-mediated senescence and differentiation, and in particular to ascertain pRb's role in a terminal cell cycle exit program associated with these functions, four specific aims are proposed: (1) Determine the mechanism of activation of cdk5 in senescent cells. (2) Ascertain the effects of constitutive cdk5 or ERM "knock-down" or loss on proliferation and tumorigenesis. (3) Investigate the mechanistic role of pRb in osteoblast differentiation in detail through use of targeted knockout mouse strains and genomic and proteomic analyses of osteoblasts derived from them. (4) Investigate the role of pRb and cdk5 in controlling cell surface expression of N-cadherin and ?-catenin in primary and immortal osteoblasts. Cancer results in part from the loss of mechanisms that restrict cell division in the end stages of tissue development and after cellular stress. Recent work from our lab and others has identified the retinoblastoma protein, pRb, as a key effector of this growth suppression, and indeed pRb function is lost in most cancer cells. We propose to investigate the molecular mechanism(s) used by pRb to prevent abnormal cell division in order to identify proteins and processes appropriate for eventual therapeutic intervention.

描述（由申请人提供）：分化、增殖和衰老之间的关系是细胞生物学的基础，在多个组织系统中重现。被鉴定为分化或细胞增殖的调节剂的分子已经证明在其他系统中具有多效性和通常意想不到的作用。例如，视网膜母细胞瘤蛋白（pRb）最初被鉴定为对儿童肿瘤视网膜母细胞瘤的发生至关重要的肿瘤抑制蛋白和细胞周期调节剂，但此后已显示在广泛的细胞类型和相关肿瘤的细胞衰老和发育中起关键作用。尽管在大多数人类肿瘤中pRb与肿瘤抑制机制有明确的联系，但对pRb在这些过程中的作用缺乏详细的了解。我们已经发现，pRb肿瘤抑制因子引起的衰老状态的各个方面依赖于cdk 5的激活和ERM蛋白的修饰和表达增加。下面描述的实验旨在阐明pRb在cdk 5活化中的功能，并探索在肿瘤生长的背景下这对衰老细胞生物学的影响。有趣的是，我们对pRb在体内和培养中正常小鼠成骨细胞分化中的作用的研究表明，pRb也可能通过cdk 5影响成骨细胞感知细胞-细胞接触和增殖停滞的能力。此外，我们发现，pRb的损失在成骨细胞分化过程中的基因表达模式有多种影响，导致积累的细胞具有明显的骨祖细胞的潜力，从而可能诱发成骨细胞的肿瘤转化。为了了解pRb介导的衰老和分化的机制，特别是为了确定pRb在与这些功能相关的终末细胞周期退出程序中的作用，提出了四个具体目标：（1）确定衰老细胞中cdk 5的激活机制。(2)确定组成性cdk 5或ERM“敲低”或缺失对增殖和肿瘤发生的影响。(3)研究pRb在成骨细胞分化中的机制作用，通过使用靶向敲除小鼠品系和基因组学和蛋白质组学分析，从它们衍生的成骨细胞。(4)研究pRb和cdk 5在控制细胞表面N-钙粘蛋白和？-钙粘蛋白表达中的作用。在初级和永生成骨细胞中的连环蛋白。癌症的部分原因是在组织发育的最后阶段和细胞应激后限制细胞分裂的机制的丧失。我们实验室和其他实验室最近的工作已经确定了视网膜母细胞瘤蛋白pRb是这种生长抑制的关键效应子，实际上pRb功能在大多数癌细胞中丢失。我们建议研究pRb用于防止异常细胞分裂的分子机制，以确定适合于最终治疗干预的蛋白质和过程。