PKC Beta Inhibition With Gemcitabine And Radiation In Pancreas Cancer

描述（由申请人提供）：放化疗是局部晚期胰腺癌的标准治疗方法，但结果不理想，局部失败率和转移扩散率较高。我们的团队开创了将基于吉西他滨的化疗与放疗相结合的新方案，以同时最大化全身效应和局部放疗效应。该提案的长期目标是通过添加PKC抑制剂恩扎鲁肽来改善吉西他滨和放疗的疗效。我们的初步数据表明，恩扎鲁肽可以增强放射治疗以及吉西他滨在胰腺癌中的作用。在这个应用程序中，我们将探讨这种观察到的增强机制。在具体目标1中，我们将确定PKC介导的Wnt信号通路抑制对胰腺癌放射敏感性的影响。我们推测PKC通过其对GSK 3的影响和Wnt信号通路的激活促进肿瘤存活。我们的初步数据表明，辐射抑制GSK 3 <$（从而增加<$-连环蛋白的水平），enzaevin可以通过抑制GSK 3 <$的磷酸化来消除这种增加。据我们所知，Wnt通路以前从未参与控制辐射反应。我们将在体外研究这种抑制是否与使用GSK 3 <$和表达显性阴性和组成性活性<$-连环蛋白的稳定细胞系的药理学调节剂观察到的放射增敏有因果关系。在具体目标2中，我们将阐明胰腺癌中吉西他滨和PKC抑制之间的相互作用机制。我们的初步数据表明，恩杂鲁肽增强吉西他滨在胰腺癌细胞系中的细胞毒性。我们假设，通过类似于SA 1中描述的机制，吉西他滨诱导Wnt信号通路的激活，并且这种作用可以被恩扎鲁肽消除。我们将使用类似于SA 1中描述的方法在体外研究这些作用。在具体目标3中，我们将确定PKC抑制，吉西他滨和辐射对Wnt信号传导和胰腺癌生长的联合作用。我们的初步数据表明，在患者体内可达到的非细胞毒性浓度下，恩扎鲁肽增强了吉西他滨和放射的细胞毒性。基于特定目标1和2中获得的知识，我们将在体外优化该组合，然后在荷人肿瘤异种移植物的裸鼠中进行优化。尽管本申请集中于理解与放化疗的协同作用，主要用于局部晚期胰腺癌的方式，但关于胰腺癌中PKC抑制作用的数据，特别是关于与吉西他滨的相互作用的数据将容易适用于转移性疾病患者。这些数据将用于将PKC抑制合理地整合到胰腺癌的新治疗方案中。基于其科学价值和我们在胰腺癌转化研究中的机构记录，我们认为这项研究很可能会证明是有益的。

DESCRIPTION (provided by applicant): Chemoradiotherapy is the standard treatment for locally-advanced pancreas cancer, but results are suboptimal with high rates of local failure and metastatic spread. Our group has pioneered novel regimens combining gemcitabine-based chemotherapy with radiation to simultaneously maximize systemic effects and local radiation effects. The long-term goal of this proposal is to improve upon the efficacy of gemcitabine and radiation through the addition of the PKC¿ inhibitor enzastaurin. Our preliminary data suggest that enzastaurin can enhance radiation as well as gemcitabine effects in pancreas cancer. In this application we will explore the mechanism of this observed enhancement. In Specific Aim 1 we will determine the effects of PKC¿- mediated inhibition of the Wnt signaling pathway on the radiosensitivity of pancreas cancer. We hypothesize that PKC¿ promotes tumor survival through its effects on GSK3¿ and activation of the Wnt signaling pathway. Our preliminary data suggests that radiation inhibits GSK3¿ (thereby increasing levels of ¿-catenin) and enzastaurin can abrogate this increase through inhibition of phosphorylation of GSK3¿. To the best of our knowledge, the Wnt pathway has never before been implicated in control of the radiation response. We will investigate in-vitro whether this suppression is causally related to the observed radiosensitization by use of pharmacological modulators of GSK3¿ and stable cell lines expressing dominant negative and constitutively active ¿-catenin. In Specific Aim 2 we will elucidate the mechanisms of interaction between gemcitabine and PKC¿ inhibition in pancreas cancer. Our preliminary data suggests that enzastaurin enhances gemcitabine cytotoxicity in pancreas cancer cell lines. We hypothesize that through a mechanism similar to that described in SA1, gemcitabine induces activation of the Wnt signaling pathway and that this effect can be abrogated by enzastaurin. We will study these effects in-vitro using an approach similar to that described in SA1. In Specific Aim 3 we will determine the combined effects of PKC¿ inhibition, gemcitabine and radiation on Wnt signaling and pancreas cancer growth. Our preliminary data demonstrates that enzastaurin, at non-cytotoxic concentrations achievable in patients, enhances the cytotoxicity of gemcitabine and radiation. Based on knowledge gained in Specific Aims 1 and 2, we will optimize this combination in-vitro and then in nude mice bearing human tumor xenografts. Although this application focuses on understanding the synergy with chemoradiotherapy, modalities used primarily for locally advanced pancreatic cancer, data regarding the effects of PKC¿ inhibition in pancreas cancer, and in particular regarding the interaction with gemcitabine would be readily applicable to patients with metastatic disease. This data will be used to rationally integrate PKC¿ inhibition into novel treatment regimens in pancreas cancer. Based on its scientific merit and our institutional track record in translational research in pancreas cancer, we feel it is highly likely that this research will prove beneficial.