Initiation, persistence, and progression of hepatocellular carcinoma

描述(申请人提供)：肝细胞癌是全球第三大致命性癌症。肝移植仍然是唯一一种预后良好的治疗方法，即使在这些病例中，5年存活率也很低，复发也很常见。此外，供肝供不应求，移植的成本和技术难度使少数患者无法接受治疗。显然，有必要对这种疾病进行基于药物的治疗，即使只是为了延长移植后的寿命。然而，肝脏代谢的复杂性使这一目标遥不可及。细胞质硫氧还蛋白还原酶(Txnrd1)在肝脏代谢中起重要作用。许多抗癌药物或候选药物，以及一些被认为具有抗癌活性的化合物，要么影响Txnrd1的活性，要么是Txnrd1 5，6代谢的底物。这表明Txnrd1在癌症的发生、持续和发展中起着至关重要的作用。然而，到目前为止，还没有在具有Txnrd1完全和特异性基因中断的系统中进行研究。因此，目前尚不清楚Txnrd1在对这些化合物的反应中扮演什么角色，以及未定义的“其他靶标”可能扮演什么角色。我们已经建立了第一个Txnrd1缺乏的肝细胞动物模型3。在拟议的研究中，我们将建立第一个Txnrd1缺陷的肝细胞癌动物模型，并使用该模型来研究Txnrd1基因缺失或缺失的细胞中肝细胞癌的启动、持续和进展。为了做到这一点，我们提出了两个具体目标。首先，我们将确定Txnrd1缺陷的肝细胞是否比正常肝细胞更容易或更难启动肝细胞癌。其次，我们将确定Txnrd1活性对原位肝癌细胞的持续和发展是必要的、有利的还是拮抗的。这个为期两年的开发R21项目的提出，旨在建立和公开传播一个新的和强大的动物模型来研究肝癌，并提供重要的了解Txnrd1在肿瘤的发生和持续/发展中的作用。 公共卫生相关性：在全球范围内，肝细胞癌是第三大致命性癌症，也是最常见的肝癌7。通常，它是慢性炎症性肝病的后遗症，包括乙型和丙型肝炎病毒感染、酒精性肝硬变和肝毒性暴露8。美国国家癌症研究所(NCI)将肝癌列为美国增长最快的癌症。在美国，每年有1.4万人死于肝细胞癌，在男性癌症相关死亡人数中排名第八。未经治疗，肝细胞癌通常在初诊后不到一年内死亡。由于它通常被诊断为晚期，并伴有严重的肝硬变，治疗可能复杂、无效、耐受性差，而且预后通常很差(http://pathology2.jhu.edu/liver/Intro.cfm)。首选的治疗方法是外科手术切除癌变的肝脏，并用未患病的供体--肝脏(http://www.mayoclinic.com/health/liver-cancer/DS00399/DSECTION=treatments).进行替换。等待捐献肝脏的人远远多于可供选择的肝脏。因此，迫切需要改进预防、检测和治疗肝细胞癌的策略。肝细胞癌对目前的化疗模式反应不佳。全肝置换术是唯一预后良好的治疗方法，但复发率较高。预后标记物正在改进，希望将移植指导到更有可能成功的患者，并正在努力促进早期诊断。然而，药物治疗的努力，也许与外科手术相结合，不应该被放弃。可能成为肝细胞癌潜在靶点的代谢活动的组合是巨大的，相对来说还没有被探索。持续的调查最终将导致改进策略。硫氧还蛋白还原酶1(Txnrd1)多年来一直被认为是一种有前途的抗癌药物靶点。至少有24种药物或候选药物具有Txnrd1抑制活性；另一大类化合物，包括有效的金属抗癌药物，被Txnrd1生物转化为具有不同生理活性和毒性的化合物。此外，我们已经证明，Txnrd1的干扰激活了药物代谢途径，这可能会改变肝细胞中的药物活性。在这个极其复杂的代谢-药理学难题中，有没有解决方案可以帮助提高肝细胞癌的存活率？我们相信有；然而，必须更好地了解肝脏中的代谢和反应途径，以促进更有成效的组合试验。为此，我们已经建立了第一个完全缺乏肝细胞Txnrd1的动物模型，在这里，我们建议建立第一个缺乏Txnrd1的肿瘤模型--肝癌。这些小鼠将使我们能够更准确地确定Txnrd1在癌症过程和抗癌治疗中的作用。在这个R21授权申请中，我们建议建立这个肝癌模型，并用它来研究Txnrd1在肝癌发生和发展中的作用。在未来，我们预计该模型将用于测量潜在药物组合的代谢/药代动力学方面，以及测试新的治疗策略对肝细胞癌的疗效。

DESCRIPTION (provided by applicant): Hepatocellular carcinoma (HCC) is the 3rd most lethal cancer worldwide. Liver transplant remains the only therapy with a favorable prognosis, and even in these cases, 5-year survival rates are low and recurrence is common 1. Moreover, donor livers are in short supply, and the cost and technical difficulty of transplantation puts therapy out of reach of all by a small minority of people stricken with the disease. Clearly there is a need for pharmaceutical-based therapies for this disease, even if just to extend longevity after transplant. However, the complexities of liver metabolism have kept this goal out of reach. Cytoplasmic thioredoxin reductase (Txnrd1) plays a major role in liver metabolism. Many anti-cancer drugs or drug-candidates, as well as some compounds thought to be active in prophylaxis against cancer initiation, either affect Txnrd1 activity or are substrates for metabolism by Txnrd1 5,6. This suggests that Txnrd1 plays crucial roles in cancer initiation, persistence, and progression. However, prior to now, no studies have been performed in systems having complete and specific genetic disruption of Txnrd1. Therefore, it is unclear what role Txnrd1 plays in responses to these compounds, and what roles undefined 'other targets' might play. We have developed the first animal model with Txnrd1-deficient hepatocytes 3. In the proposed study, we will develop the first animal model with Txnrd1-deficient HCC and to use this model to study initiation, persistence, and progression of HCC in cells that either have or lack Txnrd1. To do this, we have put forth two Specific Aims. First, we will determine whether Txnrd1-deficient hepatocytes are either more susceptible or more refractory than normal hepatocytes to initiation of HCC. Second, we will determine whether Txnrd1 activity is necessary, advantageous, or antagonistic for persistence and progression of HCC cells in situ. This two-year Developmental R21 project is proposed with the intention of establishing and publicly disseminating a novel and powerful animal model for studying HCC, and to provide important understanding of the roles of Txnrd1 in cancer initiation and persistence/progression. PUBLIC HEALTH RELEVANCE: Globally, hepatocellular carcinoma (HCC) is the 3rd most lethal cancer and the most prevalent liver cancer 7. Generally it is a sequelae of chronic inflammatory liver diseases, including hepatitis B and C virus infections, alcoholic cirrhosis, and hepatotoxic exposures 8. The National Cancer Institute (NCI) lists HCC as the most rapidly increasing cancer in the US. HCC causes 14,000 annual deaths in the US and ranks 8th in cancer- related deaths among men. Untreated, HCC is usually fatal within less than a year of primary diagnosis. Since it is often diagnosed at an advanced stage and associated with severe cirrhosis, treatments can be complicated, ineffective, and poorly tolerated, and the prognosis is generally poor (http://pathology2.jhu.edu/ liver/intro.cfm). The preferred treatment is surgical removal and replacement of the cancerous liver with a non- diseased donor-liver (http://www.mayoclinic.com/health/liver-cancer/DS00399/DSECTION=treatments). There are far more people on waiting lists for donor livers than there are livers available. Thus, there is a critical need for improved strategies for preventing, detecting, and treating HCC. HCC does not respond well to current modes of chemotherapy. Whole-liver replacement, the only therapy with a favorable prognosis, has a high incidence of recurrence. Prognostic markers are being refined in hopes of directing transplants to more likely successful patients and efforts are being made to promote earlier diagnosis. However, efforts toward pharmaceutical treatments, perhaps in combination with surgical procedures, should not be abandoned. The combinations of metabolic activities that could be potentially targeted in HCC are vast and relatively un-explored. Continued investigation will eventually lead to improved strategies. Thioredoxin reductase 1 (Txnrd1) has been viewed as a promising cancer drug-target for many years. There at least two dozen drugs or drug-candidates that have Txnrd1-inhibitory activities; another large group of compounds, including potent metal-based anti-cancer drugs, are bio-converted by Txnrd1 into compounds with different physiological activities and toxicities. In addition, we have shown that disruption of Txnrd1 activates drug metabolism pathways, which will likely alter drug activities in hepatocytes. Are there, somewhere in this richly complex metabolic-pharmacologic puzzle, solutions that could help increase the survivability of HCC? We believe there are; however a better understanding of the metabolic and response pathways in liver must be achieved to foster more productive combinatorial trials. To this end, we have developed the first viable animal models entirely lacking hepatocytic Txnrd1, and here we propose to develop the first cancer model, an HCC, lacking Txnrd1. These mice will allow us to far more accurately define the roles of Txnrd1 in cancerous processes and in anti-cancer therapies. In this R21 Grant Application, we propose to develop this HCC model and to use it to resolve the roles of Txnrd1 in initiation and progression of HCC. In the future, we foresee utility for this model in measuring metabolic/pharmacokinetic aspects of potential drug combinations, and in testing efficacy of novel therapeutic strategies on HCC.