MOLECULAR STUDY OF IFN INDUCED ANTIGROWTH ACTIVITY

干扰素（IFN）具有抗增殖、抗病毒和抗肿瘤作用。 免疫调节活性。 IFN已被用于治疗许多 肿瘤包括肾细胞癌，慢性骨髓性白血病， 乳腺癌 然而，并不是所有类型的肿瘤都对化疗敏感。 IFN诱导的抗增殖活性。 选择性的原因 IFN对肿瘤细胞的治疗效果尚不清楚。 IFN 刺激导致JAK激酶的激活， 磷酸化一个潜伏的细胞质转录因子家族 STATs（信号转导和转录激活因子）。 STAT1 是IFN-γ诱导的生物活性所必需的。 我们有 最近表明，组成型活性Stat 1可以增强IFN-γ， γ诱导的NIH 3 T3细胞抗增殖活性。 在这 建议，我提出的初步数据表明，IL-2 依赖性人T细胞对IFN-γ无反应， 抑制这些细胞中的Stat 1信号通路。此外，委员会还认为， 组成性激活的Stat 1蛋白在乳腺癌中的过度表达 癌细胞未能增强IFN-γ的抗增殖活性， 这表明除了STAT之外的其他信号通路可能 参与介导IFN-γ的抗增殖活性。 这项研究计划的总体目标是研究 IFN-γ应答机制。 首先，我将研究 IL-2依赖性T细胞中IFN-γ无反应性的分子机制 细胞 我将测试是否抑制IFN-γ反应性， 这些细胞是由于存在组成性表达的 JAK激酶抑制剂：SOCS（细胞因子抑制剂） 信号）蛋白质。 组成型表达的SOCS蛋白在 IL-2依赖性T细胞将被克隆并测试它们的能力， 抑制IFN-γ应答。 我还将研究另一种选择 假设IL-2中IFN-γ应答的抑制 依赖性T细胞是增强的蛋白酪氨酸磷酸酶的结果 活动其次，我将研究Stat 1信号对IFN-γ的影响。 在许多细胞系中的γ-介导的抗增殖活性， 过表达组成型激活的突变Stat 1蛋白。 其他 丝裂原活化蛋白激酶（MAPK） 和蛋白激酶C（PKC）途径将被检查， 对IFN-γ诱导的抗增殖活性的影响。 结果 从这些实验中获得的信息将提高我们的设计能力， 使用IFN和扩增的肿瘤的有效治疗策略 我们对细胞信号调节的了解。

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.