REGULATION OF BENIGN AND MALIGNANT HEPATOCYTE GROWTH

良性和恶性肝细胞生长的调节

• 批准号: 6541474
• 负责人: IAIN HUGH MCKILLOP
• 金额: $ 18.53万
• 依托单位: UNIVERSITY OF NORTH CAROLINA CHARLOTTE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-06 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6541474
• 关键词: G protein; athymic mouse; biological signal transduction; cAMP response element binding protein; cell growth regulation; cell line; cell membrane; cell proliferation; cellular oncology; disease /disorder etiology; enzyme linked immunosorbent assay; flow cytometry; fluorescence microscopy; gel mobility shift assay; hepatocellular carcinoma; insulinlike growth factor; laboratory rat; mitogen activated protein kinase; neoplasm /cancer pharmacology; neoplastic growth; neoplastic transformation; northern blottings; receptor expression; tissue /cell culture; transfection; western blottings

DESCRIPTION (provided by applicant): Hepatocellular cancer (HCC) leads to the death of more than 35,000 Americans annually in addition to being one of the leading causes of cancer death worldwide. Surgical resection is the best treatment available to patients with HCC but is a viable option for only 20-40% of those diagnosed. The failure to develop alternative treatments for HCC is due to our lack of understanding of the disease etiology at the cellular and molecular level. Previous reports from our laboratory have identified components of a mitogen activated protein kinase (MAPK) cascades as a focal point in processing signals of diverse origin including those associated with guanine nucleotide regulatory protein (C-protein) coupled and tyrosine kinase-linked receptors. Specifically, we have demonstrated altered expression and function of inhibitory G-proteins (Giproteins) in more than 80% of human HCC analyzed. Furthermore, activation of Gi-proteins in human and animal models of HCC leads to enhanced mitogenesis via a mitogen activated protein kinase (MAPK) cascade, an effect not observed in non-transformed hepatocytes. Other data from our laboratory demonstrate changes in hepatic insulin-like growth factor-I (IGF-l) expression in HCC and non-tumorigenic, histologically normal hepatic tissue in tumor burdened animals. Stimulation of HCC cells with IGF-l leads to increased cell mitogenesis via a MAPK pathway, an effect abrogated by inhibition of Gi-protein signaling.Based on these observations the central hypothesis of this proposal is that a MAPK cascade represents a focal link between transmembrane signals of diverse origin, regulation of which directly affects hepatic tumor proliferation at multiple levels and is intrinsically linked to the increased cell mitogenesis characteristic of HCC. It is the aim of this NIH-R01 First Award to "determine the mechanisms by which MAPK components regulate cell mitogenesis at the membrane, cytoplasmic and nuclear levels." Specifically we will (i) over-express constitutively active or dominant negative components of G-protein/IGF-l-MAPK signaling pathways in conjunction with specific pharmacological agents that stimulate or inhibit these pathways. These data will determine the role of C-protein subunits and TK-linked receptors and their associated second messengers in regulating cytoplasmic (MAPK) signaling pathways in HCC. (ii) determine the role of G-protein/IGF-l-MAPK pathways in regulating nuclear transcription factors and cell proliferation and survival in normal and transformed (HCC) hepatocytes.Because the mortality associated with HCC is so high, deciphering the mechanisms by which cell growth and tumor progression occurs is clearly of major clinical importance and significance. Accordingly, elucidation of the mechanisms controlling cell proliferation at the cytoplasmic and nuclear level represents a potential breakthrough in the development of new treatments for non-resectable HCC.

描述（由申请人提供）：肝细胞癌（HCC）除了是全球癌症死亡的主要原因之一外，每年还导致超过35，000名美国人死亡。手术切除是HCC患者的最佳治疗方法，但只有20-40%的确诊患者可以选择。未能开发出HCC的替代治疗方法是由于我们缺乏对细胞和分子水平上疾病病因学的了解。我们实验室以前的报告已经确定了丝裂原活化蛋白激酶（MAPK）级联的组成部分，作为处理不同来源的信号的焦点，包括与鸟嘌呤核苷酸调节蛋白（C蛋白）偶联和酪氨酸激酶连接受体相关的信号。具体来说，我们已经证明了在超过80%的人HCC分析中抑制性G蛋白（G蛋白）的表达和功能改变。此外，在HCC的人和动物模型中Gi蛋白的活化通过促分裂原活化蛋白激酶（MAPK）级联导致增强的有丝分裂发生，这是在非转化肝细胞中未观察到的效果。来自我们实验室的其他数据表明，在HCC和肿瘤负荷动物中的非致瘤性、组织学上正常的肝组织中，肝胰岛素样生长因子-I（IGF-1）表达的变化。用IGF-1刺激HCC细胞通过MAPK途径导致细胞有丝分裂发生增加，这一效应被Gi蛋白信号传导的抑制所消除。基于这些观察，该提议的中心假设是MAPK级联反应代表了不同来源的跨膜信号之间的焦点联系，其调节在多个水平上直接影响肝肿瘤增殖，并与细胞有丝分裂发生的增加内在相关HCC的特征。NIH-R 01一等奖的目的是“确定MAPK成分在膜、细胞质和细胞核水平调节细胞有丝分裂的机制。“具体来说，我们将（i）过表达G蛋白/IGF-1-MAPK信号通路的组成性活性或显性负性组分，并结合刺激或抑制这些通路的特定药理学试剂。这些数据将确定C蛋白亚基和TK连接的受体及其相关的第二信使在调节细胞质（MAPK）信号通路在HCC中的作用。(ii)确定G蛋白/IGF-1-MAPK通路在调节核转录因子和细胞增殖中的作用，以及正常和转化（HCC）肝细胞的存活。因此，阐明在细胞质和细胞核水平控制细胞增殖的机制代表了在开发用于不可切除的HCC的新治疗方法方面的潜在突破。