Immunoregulatory effects of novel mTOR inhibitors

描述（由申请人提供）：该项目的目标是研究一类新的癌症治疗药物如何影响淋巴细胞功能。这些化合物是观察氨酸/苏氨酸激酶mTOR（哺乳动物雷帕霉素靶点）的活性位点抑制剂。mTOR激酶存在于两个复合物中，称为mTORC1和mTORC2，具有不同的底物和功能。天然化合物雷帕霉素是一种选择性mTOR抑制剂，可有效抑制淋巴细胞增殖，临床上用于免疫抑制。然而，雷帕霉素是一种变构性mTORC1抑制剂，不会急性抑制mTORC2。新型的活性位点（atp竞争）mTOR抑制剂阻断两种mTOR复合物的所有功能，在癌细胞系中具有比雷帕霉素更有效的细胞抑制和细胞毒性作用。因此，全世界都在努力开发用于癌症治疗的活性位点mTOR抑制剂。然而，活性位点mTOR抑制剂的免疫调节特性尚未报道。确定这些药物对淋巴细胞活化的影响将揭示它们作为新型免疫抑制剂的潜力，同时也解决了在癌症治疗环境中对宿主防御和抗肿瘤免疫的关注。我们的初步数据表明，与未转化的淋巴细胞相比，活性位点mTOR抑制剂对白血病细胞具有选择性毒性。在这个项目中，我们将使用一组精心挑选的实验方法来解决一个特定的目标：比较雷帕霉素和活性位点mTOR抑制剂对淋巴细胞激活和分化的影响。我们将使用体外和体内系统，并研究T细胞和B细胞。抑制剂将在一个浓度范围内进行研究，以方便药效的比较。对于T细胞，我们将使用T细胞受体转基因系统来测量对同源抗原的增殖反应。我们将采用过继性转移方法来评估T细胞在体内的扩增。我们还将测量细胞因子介导的生存和辅助T分化。对于B细胞，我们将测量对不同丝裂原和细胞因子的增殖和存活。我们将比较B细胞向抗体分泌细胞的分化及其在免疫小鼠中产生抗体的能力。我们将把淋巴细胞的功能反应与信号转导事件联系起来，以确定抑制剂作用的分子基础。

DESCRIPTION (provided by applicant): The goal of this project is to study how a novel class of cancer therapeutics impact lymphocyte function. These compounds are active-site inhibitors of the bserine/threonine kinase mTOR (mammalian target of rapamycin). The mTOR kinase is present in two complexes, termed mTORC1 and mTORC2, with distinct substrates and function. The natural compound rapamycin is a selective mTOR inhibitor that potently suppresses lymphocyte proliferation, and is used clinically for immunosuppression. However, rapamycin is an allosteric mTORC1 inhibitor that does not acutely inhibit mTORC2. Novel, active-site (ATP-competitive) mTOR inhibitors block all functions of both mTOR complexes and have more potent cytostatic and cytotoxic effects than rapamycin in cancer cell lines. Consequently, there are worldwide efforts to develop active-site mTOR inhibitors for cancer therapy. The immunoregulatory properties of active-site mTOR inhibitors, however, have not been reported. Defining the effects of these agents on lymphocyte activation will reveal their potential as novel immunosuppressants, while also addressing concerns about host defense and anti- tumor immunity in the cancer therapy setting. Our preliminary data suggest that active-site mTOR inhibitors are selectively toxic to leukemia cells compared to nontransformed lymphocytes. In this project we will use a carefully selected set of experimental approaches to address one specific aim: to compare the effects of rapamycin and active-site mTOR inhibitors on lymphocyte activation and differentiation. We will use both in vitro and in vivo systems, and study both T cells and B cells. Inhibitors will be studied over a concentration range to facilitate comparisons of potency. For T cells, we will use T cell receptor-transgenic systems to measure proliferation in response to cognate antigen. We will employ adoptive transfer approaches to assess T cell expansion in vivo. We will also measure cytokine-mediated survival and T helper differentiation. For B cells, we will measure proliferation and survival in response to different mitogens and cytokines. We will compare the differentiation of B cells into antibody-secreting cells and their ability to produce antibodies in immunized mice. We will correlate the functional responses of lymphocytes with signal transduction events, to determine the molecular basis for inhibitor effects. PUBLIC HEALTH RELEVANCE: This project will study a newly discovered class of anti-cancer drugs and determine how they affect the immune response. This work will help us understand and predict potential side effects of these drugs on the immune system of cancer patients. In addition, we might find evidence that the drugs will be useful to treat immune-related diseases.