Cytokine modulated model growth inhibitory mechanisms

描述（由申请人提供）：细胞因子通过诱导肿瘤中生长抑制基因的表达或通过对其进行免疫反应来调节肿瘤细胞的体内生长。干扰素家族细胞因子调节多种生理反应，如抗病毒、抗肿瘤和免疫功能。通过与其他细胞因子的相互作用，ifn成为一个庞大的细胞间信号网络的组成部分，促进体内抗肿瘤和抗病原体监测系统。在早期的研究中，我们证明了ifn诱导的抗肿瘤作用，特别是细胞凋亡，可以通过全反式维甲酸（RA）协同增强。这种维生素a代谢物本身在许多实验和临床模型中起生长抑制剂的作用。一些临床研究也证实了IFN/RA的有效肿瘤抑制作用。我们假设IFN/RA利用新的基因产物抑制肿瘤生长。为了确定IFN/ ra诱导细胞凋亡的关键分子，我们使用了一种遗传策略，并确定了几个与类视黄酮干扰素诱导死亡（GRIM）相关的基因。其中一个新的基因产物，GRIM-19，通过细胞凋亡抑制生长。我们等人的前期研究表明，其活性受到DNA病毒癌蛋白和一些细胞蛋白的抑制。这些观察结果表明其有效的抗肿瘤特性。在上一个资助期内，我们已经通过细胞系模型证明了GRIM-19与信号传感器和转录激活因子3 （STAT3）结合并抑制其促进生长的作用。STAT3是一种休眠细胞因子调控的转录因子，在许多人类肿瘤中通过致癌信号被组成性激活。STAT3活性在正常细胞中受反馈抑制剂调节。持续的STAT3活性通过刺激参与这些反应的各种细胞基因的表达来促进肿瘤细胞的存活、增殖和转移。虽然STAT3的致癌激活是一个重要的步骤，但我们认为在促进肿瘤生长之前，其抑制剂的丢失或失活也可能在这一过程中发挥关键作用。在初步研究中，我们在异种移植模型中发现GRIM-19抑制STAT3诱导的组成型肿瘤生长和转移。与此一致的是，我们在几种原发性人类肿瘤中观察到GRIM-19的表达缺失和突变，这与stat3诱导基因的强烈上调和细胞生长的促进有关。在这个更新的应用中，我们将通过敲除和转基因小鼠来研究GRIM-19与体内肿瘤生长的生物学相关性。我们将通过体外和体内模型研究（在原发肿瘤中发现的）grim19突变对癌基因诱导的肿瘤生长促进的影响。尽管在许多肿瘤中已知STAT3的失调，但其失调的分子机制，特别是其抑制剂在肿瘤发展中的作用研究甚少。本应用程序中提出的研究将确定GRIM-19中肿瘤特异性功能障碍如何影响这一新的生长调节途径的功能。公共卫生相关性：鳞状细胞癌（SCC）是一种非黑色素瘤皮肤癌（NMSC），其病例呈上升趋势，在美国每年有超过一百万的新病例，在许多鳞状细胞癌和其他癌症中发现持续激活的STAT3，这与肿瘤的侵袭性生长有关。这一提议首次明确了STAT3抑制剂GRIM-19在肿瘤抑制中的重要性。从这些研究中获得的信息将有助于开发治疗SCCs和其他癌症的设计疗法，在这些癌症中观察到异常的STAT3活性。

DESCRIPTION (provided by applicant): Cytokines regulate neoplastic cell growth in vivo either by inducing the expression of growth suppressor genes in tumors or by mounting an immune response against them. The interferon family of cytokines regulates several physiologic responses such as antiviral, antitumor, and immune functions. By interacting with other cytokines, IFNs become an integral part of a large of intercellular signaling network that promotes anti-tumor and anti-pathogen surveillance system in vivo. In an earlier study, we demonstrated that the IFN-induced anti-tumor actions, especially apoptosis, could be synergistically augmented by all-trans retinoic acid (RA). This vitamin-A metabolite by itself acts as a growth inhibitor in many experimental and clinical models. Some clinical studies also demonstrated the potent tumor inhibitory effects of IFN/RA. We hypothesized that IFN/RA employs novel gene products for suppressing tumor growth. To identify the critical molecules involved in IFN/RA-induced apoptosis, we have used a genetic strategy and identified several Genes associated with Retinoid-Interferon-induced Mortality (GRIM). One such novel gene product, GRIM-19, suppresses growth via apoptosis. Previous studies by us and others showed that its activity suppressed by DNA viral oncoproteins and some cellular proteins. These observations indicate its potent anti-oncogenic characteristics. During the last funding period we have shown that GRIM-19 binds to Signal Transducer and Activator of Transcription 3 (STAT3) and suppresses its growth promoting action using cell line models. STAT3, a dormant cytokine-regulated transcription factor, is constitutively activated in a number of human tumors by oncogenic signals. STAT3 activity is regulated in normal cells by feedback inhibitors. Persistent STAT3 activity promotes survival, proliferation, metastasis of tumor cells by stimulating the expression of various cellular genes involved in those responses. Although oncogenic activation of STAT3 is an important step, we suggest that loss or inactivation of its inhibitors may also play a critical step in this process prior to the promotion of tumor growth. In preliminary studies, we showed that GRIM-19 suppress constitutive STAT3- induced tumor growth and metastasis using xenograft models. Consistent with these, we observed a loss of expression and mutations in GRIM-19 in several primary human tumors, which correlated with a strong upregulation of STAT3-inducible genes and promotion of cell growth. In this renewal application, we will investigate the biological relevance of GRIM-19 to tumor growth in vivo using knockout and transgenic mice. We will investigate the impact of grim19 mutations (found in primary tumors) on oncogene-induced tumor growth promotion using in vitro and in vivo models. Although a deregulation of STAT3 is known in many tumors, the molecular mechanisms of its deregulation, specifically the role of its inhibitors in tumor development are poorly studied. The studies proposed in this application will define how tumor- specific dysfunctions in GRIM-19 affect the functioning of this new growth regulatory pathway. PUBLIC HEALTH RELEVANCE: Cases of Squamous cell carcinoma (SCC), a form of non-melanoma skin cancer (NMSC), are on the rise, with over a million new cases annually in U.S.A. Persistently activated STAT3 is found in many SCCs and other cancers, which correlates with an aggressive growth of tumors. This proposal for the first time will define the importance of GRIM-19, an inhibitor of STAT3, in tumor suppression. The information gained from these studies will be useful in developing designer therapies for treating SCCs and other cancers, where abnormal STAT3 activities are observed.