PKC Beta Inhibition With Gemcitabine And Radiation In Pancreas Cancer

描述(申请人提供)：放化疗是局部晚期胰腺癌的标准治疗方法，但结果不佳，局部失败率高，转移扩散。我们小组开创了将以吉西他滨为基础的化疗与放射治疗相结合的新方案，以同时最大限度地发挥全身效应和局部辐射效应。这项建议的长期目标是通过增加PKC抑制剂enzastaurin来改善吉西他滨和放射治疗的疗效。我们的初步数据表明，在治疗胰腺癌的过程中，恩扎他林可以增强放射和吉西他滨的作用。在本申请中，我们将探索这种观察到的增强的机制。在特定的目标1中，我们将确定PKC介导的Wnt信号通路的抑制对胰腺癌放射敏感性的影响。我们假设PKC通过影响GSK3和激活Wnt信号通路来提高肿瘤存活率。我们的初步数据表明，辐射抑制GSK3？(从而增加-连环蛋白水平)，而enzastaurin可以通过抑制GSK3？的磷酸化来消除这种增加。据我们所知，Wnt通路以前从未参与过辐射反应的控制。我们将在体外研究这种抑制是否与所观察到的放射增敏有关，使用GSK3的药理调节剂和稳定的表达显性阴性和结构性活性的连环蛋白的细胞系。在特定的目标2中，我们将阐明吉西他滨与抑制胰腺癌中PKC的相互作用机制。我们的初步数据表明，在胰腺癌细胞系中，恩施他滨可增强吉西他滨的细胞毒作用。我们推测，吉西他滨通过与SA1中描述的类似的机制，诱导Wnt信号通路的激活，并且这一作用可以被苯扎托林所阻断。我们将使用类似于SA1中描述的方法在体外研究这些效应。在具体目标3中，我们将确定PKC抑制、吉西他滨和放射对Wnt信号和胰腺癌生长的联合作用。我们的初步数据显示，在患者可达到的非细胞毒性浓度下，扎他汀可增强吉西他滨和放射的细胞毒性。基于在特定目标1和2中获得的知识，我们将在体外优化这种组合，然后在携带人类肿瘤移植瘤的裸鼠身上进行优化。虽然这项应用侧重于了解与化疗和放射治疗的协同作用，主要用于局部晚期胰腺癌，但有关PKC抑制在胰腺癌中的作用的数据，特别是关于与吉西他滨的相互作用的数据，将很容易适用于转移性疾病患者。这些数据将被用于将PKC抑制合理地整合到胰腺癌的新治疗方案中。基于它的科学价值和我们在胰腺癌转化研究方面的机构记录，我们认为这项研究极有可能被证明是有益的。

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.