Evaluation of novel FoxM1 inhibitors against liver cancer

描述（由申请人提供）：人类肝细胞癌（HCC）是全球第五大常见癌症，也是全球第三大癌症死亡原因。所有传统的肝癌治疗方法都充满了副作用，而且效率有限。因此，寻找针对HCC生长的潜在分子事件并通过阻断细胞分裂和选择性诱导肿瘤细胞凋亡来干扰HCC发展的新药是很重要的。叉头盒M1 （FoxM1）是近年来因其在包括HCC在内的许多癌症中的重要性而受到关注的一个特殊基因。FoxM1是一种转录因子，它调节许多参与细胞周期调节的基因的表达。有趣的是，研究发现FoxM1对于小鼠HCC的发展至关重要，这表明抑制FoxM1可能是治疗HCC的一种有希望的策略。在我们的初步研究中，我们确定了抗生素噻唑类化合物Siomycin A和thiiostrepton是FoxM1的有效抑制剂。本课题旨在探讨Siomycin A/thiostrepton的分子作用机制，并在小鼠肝癌模型中检测其体内疗效。在第一个特定目标中，我们将确定Siomycin A/thiostrepton如何抑制FoxM1的转录活性。接下来，我们将验证FoxM1下调是Siomycin a / thiiostrepton诱导细胞凋亡的关键事件的假设。为了评价Siomycin A/ thiiostrepton作为体内抗癌药物的疗效，我们将在体外用3株对噻唑类抗生素敏感的人肝癌细胞株诱导胸腺小鼠移植瘤。Siomycin A/thiostrepton治疗对异种移植肿瘤FoxM1表达和生长的影响将在这些小鼠中进行研究。此外，为了测试噻唑类抗生素的抗癌特性，我们将采用二乙基亚硝胺(DEN)/苯巴比妥（PB）诱导雄性小鼠肝肿瘤方案和新的ARF-/- Rosa-26 FoxM1b TG小鼠模型进行侵袭性转移性肝癌的研究。我们将测试Siomycin A/thiostrepton是否可以抑制这些小鼠的HCC生长和转移。此外，我们将测试代表脱氢哌替啶核心的硫链顿的小片段是否也抑制FoxM1，并表现出抗癌肝癌的特性。这些数据不仅有助于开发新的抗肝癌药物，也将有助于更好地了解HCC的病因。如果噻唑类抗生素的毒性较低，并能导致小鼠肝肿瘤消退，我们将得出结论，这些化合物可能具有进一步临床开发抗肝癌的潜力。

DESCRIPTION (provided by applicant): Human hepatocellular carcinoma (HCC) is the fifth most common cancer, and the third leading cause of cancer death worldwide. All conventional treatments for liver cancer are fraught with side effects and limited efficiency. Hence, it is important to identify novel drugs that target the underlying molecular events of HCC growth and interfere with HCC development by blocking cell division and selectively inducing tumor cell apoptosis. One particular gene that has gained attention in recent years due to its importance in a number of cancers including HCC is Forkhead Box M1 (FoxM1). FoxM1 is a transcription factor that regulates the expression of a number of genes that are involved in cell cycle regulation. Interestingly, it was found that FoxM1 is essential for the development of HCC in mice, suggesting that inhibition of FoxM1 might be a promising strategy for treating HCC. In our preliminary studies, we identified the antibiotic thiazole compounds Siomycin A and thiostrepton as potent inhibitors of FoxM1. The goal of this proposal is to investigate the molecular mechanisms of action of Siomycin A/thiostrepton and to test their efficacy in vivo in mouse models of liver cancer. In the first specific aim we will determine how Siomycin A/thiostrepton inhibit the transcriptional activity of FoxM1. Next, we will test the hypothesis that downregulation of FoxM1 is a key event that leads to Siomycin A/thiostrepton-induced apoptosis. To evaluate the efficacy of Siomycin A/thiostrepton as anticancer agents in vivo, we will use 3 human liver cancer cell lines that are sensitive to thiazole antibiotics in vitro to induce xenograft tumors in athymic mice. The effect of Siomycin A/thiostrepton treatment on FoxM1 expression and growth of xenograft tumors will be examined in these mice. Furthermore, to test the anticancer properties of the thiazole antibiotics we will use a Diethylnitrosamine (DEN)/Phenobarbital (PB) liver tumor induction protocol in male mice and a new ARF-/- Rosa-26 FoxM1b TG mouse model of aggressive metastatic liver cancer. We will test if Siomycin A/thiostrepton can inhibit HCC growth and metastasis in these mice. In addition, we will test whether the small fragment of thiostrepton representing the dehydropiperidine core also inhibits FoxM1 and exhibits anticancer properties against liver cancer. These data may not only help to develop new drugs against liver cancer, but also will help to better understand the etiology of HCC. If the thiazole antibiotics have low toxicity and lead to liver tumor regression in mice, we will conclude that these compounds may have a potential for further clinical development against liver cancer. PUBLIC HEALTH RELEVANCE: Human hepatocellular carcinoma (HCC) is the fifth most common cancer, and the third leading cause of cancer death worldwide. All conventional treatments for liver cancer are fraught with side effects and limited efficiency. Hence, it is important to identify novel drugs that target the underlying molecular events of HCC growth and interfere with HCC development. It was shown that oncogene FoxM1 is essential for the development of HCC, suggesting that inhibition of FoxM1 might be a promising strategy for treating HCC. Thiazole antibiotics Siomycin A and thiostrepton were identified in our laboratory as potent inhibitors of FoxM1 and inducers of apoptosis in liver cancer cells. The goal of this proposal is to investigate the molecular mechanisms of action of Siomycin A/thiostrepton and to test their efficacy in vivo in mouse models of liver cancer. Thiazole antibiotics could be promising drugs against HCC because they induce cell death in cancer, but not in normal cells. Completion of our proposal will enable us to determine if thiazole antibiotics are suitable for further clinical development.