MOLECULAR STUDY OF IFN INDUCED ANTIGROWTH ACTIVITY

干扰素(IFN)具有抗增殖、抗病毒和 免疫调节活性。干扰素已被用于治疗许多 肿瘤包括肾细胞癌、慢性粒细胞白血病、 乳腺癌。然而，并不是所有类型的肿瘤都对 干扰素诱导的抗增殖活性。选择的原因是 干扰素对肿瘤细胞的治疗效果尚不清楚。干扰素 刺激导致JAK激酶的激活，然后 使一组潜在的细胞质转录因子磷酸化 命名为STATS(信号转导和转录激活因子)。状态1 对于干扰素-γ诱导的生物活性是必不可少的。我们有 最近发现，具有结构性活性的STAT1可以增强干扰素-1。 伽马能诱导NIH3T3细胞的抗增殖活性。在这 建议，我给出的初步数据表明，IL-2 依赖性人类T细胞对干扰素-γ无反应，原因是 抑制这些细胞中的STAT1信号通路。此外， 组成型激活的STAT1蛋白在乳腺组织中的过表达 肿瘤细胞未能增强干扰素-1的抗增殖活性 Gamma提示除了STAT之外的其他信号通路可能 参与介导干扰素-γ的抗增殖活性。 这项研究计划的总体目标是研究分子 干扰素-γ的应答机制。首先，我会研究一下 IL-2依赖T细胞干扰素-γ无应答的分子机制 细胞。我将测试干扰素-伽马应答的抑制是否在 这些细胞的存在是由于结构性表达的 JAK激酶的抑制物：SOCS(细胞因子的抑制物 信号)蛋白质。重组表达的SOCS蛋白在 依赖IL-2的T细胞将被克隆并测试其能力 抑制干扰素-γ反应。我还将研究一种替代方案 IL-2对干扰素-γ反应的抑制假说 依赖T细胞是蛋白酪氨酸磷酸酶增强的结果 活动。其次，我将研究STAT1信号对干扰素-1的影响。 几种细胞系中伽马介导的抗增殖活性 过表达一个成分激活的突变的STAT1蛋白。其他 丝裂原活化蛋白激酶(MAPK)等信号通路 和蛋白激酶-C(PKC)通路将被检测其 对干扰素-γ诱导的抗增殖活性的影响。结果 从这些实验中得到的结果将提高我们的设计能力 应用IFN和Expand治疗肿瘤的有效策略 我们对细胞信号的一般规则的了解。

Interferons (IFNs) have antiproliferative, antiviral and immunomodulatory activities. IFNs have been used to treat a number of tumors including renal cell carcinoma, chronic myelogenous leukemia, breast cancer. However, not all types of tumors are sensitive to the IFN-induced antiproliferative activity. The reason for the selective therapeutic effectiveness of IFNs on tumor cells is not known. IFN stimulation leads to the activation of JAK kinases, which then phosphorylates a family of latent cytoplasmic transcription factors named STATs (signal transducer and activator of transcription). Stat1 is essential for IFN-gamma-induced biological activity. We have recently shown that the constitutively active Stat1 can enhance IFN- gamma induced antiproliferative activity in NIH3T3 cells. In this proposal, I present the preliminary data which show that the IL-2 dependent human T cells are unresponsive to IFN-gamma due to the inhibition of Stat1 signaling pathway in these cells. Furthermore, overexpression of constitutively activated Stat1 protein in breast cancer cells failed to enhance the antiproliferative activity of IFN- gamma suggesting that other signaling pathways in addition to STAT may be involved in mediating the antiproliferative activity of IFN-gamma. The overall goal of this research proposal is to study the molecular mechanism of IFN-gamma responsiveness. First, I will study the molecular mechanism of IFN-gamma unresponsiveness in IL-2 dependent T cells. I will test if the inhibition of IFN-gamma responsiveness in these cells is due to the presence of constitutively expressed inhibitors of the JAK kinases: the SOCS (Suppresser of the Cytokine Signaling) proteins. The constitutively expressed, SOCS proteins in IL-2 dependent T cells will be cloned and tested for their ability to inhibit IFN-gamma response. I will also examine an alternative hypothesis that the inhibition of IFN-gamma response in the IL-2 dependent T-cells is a result of enhanced protein tyrosine phosphatase activity. Second, I will examine the effect of Stat1 signaling on IFN- gamma-mediated antiproliferative activity in a number of cell lines by overexpressing a constitutively activated mutant Stat1 protein. Other signaling pathways such as the Mitogen-Activated Protein Kinase (MAPK) and the Protein Kinase-C (PKC) pathways will be examined for their effects on IFN-gamma-induced antiproliferative activity. Results obtained from these experiments will improve our ability to design effective therapeutic strategies for tumors employing IFNs and expand our knowledge of the regulations of cell signaling in general.