Therapy for Liver Cancer by Targeting Energy Metabolism

描述(由申请人提供)： 肝癌是世界上最致命、最无法治愈的癌症之一。在美国，由于丙型肝炎的近乎流行的上升，肝癌的发病率正在迅速增长(几乎每三年翻一番)。我们的目标是开发一种新的治疗策略，包括直接经动脉注射有效的能量代谢抑制物来治疗肝癌。大多数人类恶性肿瘤，包括肝癌，都以高速率消耗葡萄糖，导致细胞生长所必需的能量产生增加。这一特性在临床上通常用于正电子发射断层扫描(PET)，以检测癌症并评估其恶性程度。我们实验室的工作已经确定了糖酵解为快速生长的癌细胞产生能量的重要性。这一过程中的一个主要参与者是II型己糖激酶，它是位于线粒体内的葡萄糖代谢的起始酶，由于II型己糖激酶基因的扩增，在许多癌细胞中上调，导致活性显著增加。最近，在原发性和转移性肝癌以及其他人类癌症，如黑色素瘤、乳腺癌、结肠癌和胰腺癌中都发现了II型己糖激酶活性的增加。因此，II型己糖激酶为阻止糖酵解从而杀死癌细胞提供了一个新的和理想的靶点。在早期的研究中，我们发现烷化剂3-溴丙酮酸在组织培养中诱导整个大鼠肝癌细胞群快速死亡(在12小时内)。在这里，3-溴丙酮酸作为一种从未被测试为抗癌剂的药物，通过直接阻断II型己糖激酶和抑制线粒体ATP合成机制，发挥了肿瘤糖酵解的特异性抑制作用。这种双重作用会完全抑制癌细胞的能量产生能力，导致它们迅速死亡。在随后的体内研究中，通过肝动脉直接将3-溴丙酮酸单次注射到兔种植性肝肿瘤中，可导致90%以上的肿瘤破坏，而对肝脏或其他器官没有任何毒性。动脉内长时间注入3-溴丙酮酸可显著延长动物的存活时间并治愈60%以上的动物。在处死时，治疗8个月后，尸检中没有发现有存活的肿瘤组织。选择动脉途径是为了增加肿瘤内的药物浓度并最大限度地提高特异性。这项初步工作为本文提出的研究奠定了坚实的基础，该研究的重点是开发一种新的方法，通过直接动脉注射靶向能量代谢的药物来治疗肝癌。具体目标有两个，将用于：1)鉴定高糖酵解/高II型己糖激酶在人肝肿瘤(新鲜切除)中的表达，从而创建肝肿瘤文库，并建立这些肿瘤对3-溴丙酮酸的敏感性；2)研究3-溴丙酮酸动脉内治疗对VX-2兔肝癌模型长期存活和治愈的疗效。这项结合使用放射学和基础科学研究工具的转化性研究是为临床试验奠定坚实基础的必要和基础。

DESCRIPTION (provided by applicant): Liver cancer is one of the most highly lethal and incurable cancers in the world. In the United States, the incidence of liver cancer is growing rapidly (almost doubling every 3 years) due to the concomitant near-epidemic rise in hepatitis C. Our objective is to develop a new therapeutic strategy consisting of direct intraarterial delivery of potent inhibitors of energy metabolism to treat liver cancer. Most human malignant tumors including liver cancer consume glucose at high rates resulting in increased energy production essential for cell growth. This property is commonly used clinically in Positron Emission Tomography (PET) to detect cancers and assess their degree of malignancy. Work performed in our laboratory has determined the importance of glycolysis to generate energy for rapidly growing cancer cells. A major player in this process is Type II hexokinase, the initial enzyme of glucose metabolism located within the mitochondria, which is up-regulated in many cancer cells due to amplification of the Type II hexokinase gene, resulting in markedly increased activity. This increase in Type II hexokinase activity has recently been found in both primary and metastatic liver cancer as well as other human cancers, such as melanoma, breast, colon, and pancreas. Type II hexokinase therefore provides a new and ideal target for arresting glycolysis and thereby killing cancer cells. In earlier studies, we found that the alkylating agent, 3-bromopyruvate, induced rapid cell death (within 12 hours) of an entire rat hepatoma cell population in tissue culture. Here, 3-bromopyruvate, which had never been tested as an anti-cancer agent, acts as a specific inhibitor of tumor glycolysis both by blocking Type II hexokinase directly and inhibiting the mitochondrial ATP synthetic machinery. This dual action results in complete inhibition of the energy producing capabilities of cancer cells leading to their rapid death. In subsequent in-vivo studies, a single bolus injection of 3-bromopyruvate via the hepatic artery directly into rabbit implanted liver tumors caused over 90% tumor destruction without any toxicity to the liver or other organs. Prolonged intraarterial infusion of 3-bromopyruvate resulted in significantly prolonged survival and the cure of over 60% of the animals. At the time of sacrifice, 8 months after therapy, no viable tumor tissue was found at necropsy. The arterial route was selected to increase drug concentration within the tumor and maximize specificity. This preliminary work forms a firm foundation for the study proposed here, which is focused on developing a new approach in the treatment of liver cancer by direct intraarterial injection of agents that target energy metabolism. Specific aims are two-fold and will be to: 1) Characterize the expression of the high glycolytic/high Type II hexokinase phenotype in human liver tumors (freshly resected) thereby creating a library of hepatic tumors and establish the sensitivity of these tumors to 3-bromopyruvate; and 2) Study the efficacy of intraarterial therapy with 3-bromopyruvate on long-term survival and cure in the Vx-2 rabbit model of liver cancer. This translational study combining the use of radiological and basic science research tools is both necessary and fundamental to firmly lay the groundwork for clinical trials.