ABNORMAL TCR/CD3 SIGNAL TRANSDUCTION IN CANCER

由于尚不清楚的原因，肿瘤细胞往往不能触发足够的免疫反应。 免疫反应之前，我们证明了刺激 将IL-2基因直接导入肿瘤细胞， 使用逆转录病毒基因转移。当肿瘤在小鼠中进行性生长时 接种亲本CMS 5肿瘤细胞，那些基因工程化以 分泌IL-2被排斥或生长缓慢。此外，具有父母的小鼠 肿瘤，但不是那些缓慢生长的IL-2分泌肿瘤， 免疫抑制，反映在生化和功能异常。 我们的工作假设是，低水平的PTKs如lck干扰 有几种T细胞激活途径例如，LCK负责 用于磷酸化TcR的ζ链，这是 ZAP- 70的招募和随后的下游事件， 细胞因子的合成。lck还激活P13激酶， 与CD 28一起进入共刺激通路。我们进一步建议， 肿瘤来源的IL-2在体内的分泌改变了肿瘤的结果， 否则淋巴细胞和肿瘤细胞之间的相互作用无效， 可能通过激活与IL-2 β链相关的lck 受体的激活的lck的可用性使得能够启动 下游事件导致的扩展和维护的IL-2 响应性抗肿瘤群体。肿瘤进展可能是一个后果 亲代肿瘤携带者的免疫反应下调 动物在本申请中，我们将确定是否无反应性由于 缺乏共刺激或缺乏II类有助于 对CMS 5无反应。第二，我们将确定是否减少 与T细胞活化相关的PTK水平涉及 异常的T细胞功能和改变的信号转导， 转基因小鼠，并通过比较依赖于 在PTK上。第三，我们将确定潜在的分子机制， lck、fyn和TcR zeta的表达降低。第四，我们将定义 异常信号转导对T细胞功能的远端后果。 这个独特的模型应该使我们能够测试我们的工作假设， 获得有关潜在机制的重要信息， 免疫抑制可能会损害潜在的成功 免疫疗法这可能允许操纵局势， 优势

For reasons that are unclear tumor cells often fail to trigger an adequate immune response. Previously, we showed that it was possible to stimulate an immune response by introducing the lL-2 gene directly into tumor cells using retroviral gene transfer. While tumors grew progressively in mice inoculated with parental CMS5 tumor cells, those genetically engineered to secrete lL-2 were rejected or grew slowly. Moreover, mice with parental tumors, but not those with slowly growing lL-2 secreting tumors were immunosuppressed, reflected in biochemical and functional abnormalities. Our working hypothesis is that low levels of PTKs such as lck interfere with several T cell activation pathways. For example, lck is responsible for phosphorylating the zeta chain of the TcR which is a prerequisite to the recruitment of ZAP- 70 and the subsequent downstream events that lead to cytokine synthesis. lck also activates P13-kinase which then associates with CD28, feeding into the costimulatory pathway. We further propose that the secretion of tumor derived lL-2 in vivo alters the outcome of the otherwise ineffective interaction between lymphocytes and tumor cells, possibly by activating lck associated with the beta chain of lL-2 receptor. The availability of activated lck enables the initiation of downstream events resulting in the expansion and maintenance of an lL-2 responsive anti-tumor population. Tumor progression may be one consequence of the downregulation of the immune response in parental tumor bearing animals. In this application, we will determine whether anergy due to the lack of costimulation or the absence of class II contributes to unresponsiveness to CMS5. Second, we will determine whether decreased levels of the PTKs associated with T cell activation are implicated in abnormal T cell function and altered signal transduction by using transgenic mice and by comparing signal transduction events that depend upon PTKs. Third, we will identify the molecular mechanisms underlying decreased expression of lck, fyn, and TcR zeta. Fourth, we will define distal consequences of abnormal signal transduction on T cell function. This unique model should enable us to test our working hypothesis and to obtain important information about mechanisms underlying the immunosuppression that can compromise potentially successful immunotherapies. This may permit the manipulation of the situation to our advantage.