Evaluation of novel FoxM1 inhibitors against liver cancer

描述(申请人提供)：人类肝细胞癌是世界上第五大常见癌症，也是导致癌症死亡的第三大原因。所有传统的肝癌治疗方法都充满了副作用和有限的疗效。因此，寻找针对肝癌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预肝癌发展的新型药物是非常重要的。近年来，由于其在包括肝癌在内的多种癌症中的重要性而受到关注的一个特定基因是Forkhead Box M1(FOXM1)。FOXM1是一种转录因子，可调节参与细胞周期调控的多个基因的表达。有趣的是，FOXM1被发现对小鼠肝细胞癌的发展是必不可少的，这表明抑制FOXM1可能是治疗肝细胞癌的一种有前途的策略。在我们的初步研究中，我们确定了抗生素噻唑类化合物西奥霉素A和硫代链球菌素是FOXM1的有效抑制剂。本研究的目的是研究西奥霉素A/硫代链球菌素的分子作用机制，并在小鼠肝癌模型上测试其体内疗效。在第一个特定目标中，我们将确定西奥霉素A/硫链霉菌如何抑制FOXM1的转录活性。接下来，我们将验证FOXM1下调是导致西奥霉素A/硫链霉菌诱导细胞凋亡的关键事件的假设。为了评价西奥霉素A/硫代链球菌素作为体内抗癌药物的效果，我们用3株对噻唑类抗生素敏感的人肝癌细胞株在体外诱导裸鼠移植瘤。将在这些小鼠中检测西霉素A/硫链霉菌治疗对FOXM1表达和异种移植瘤生长的影响。此外，为了测试噻唑类抗生素的抗癌性能，我们将使用二乙基亚硝胺(DEN)/苯巴比妥(PB)诱导雄性小鼠肝癌的方案和一种新的ARF-/-ROSA-26 FoxM1b TG小鼠侵袭性转移性肝癌模型。我们将测试西奥霉素A/硫代链球菌素是否能抑制这些小鼠的肝癌生长和转移。此外，我们还将测试代表脱氢哌啶核心的硫链霉菌小片段是否也抑制FOXM1，并显示出抗癌活性。这些数据不仅可能有助于开发抗肝癌的新药，还将有助于更好地了解肝细胞癌的病因。如果噻唑类抗生素具有低毒，并能使小鼠肝肿瘤消退，我们将得出结论，这些化合物可能具有进一步开发抗肝癌临床应用的潜力。 公共卫生相关性：人类肝细胞癌是全球第五大常见癌症，也是导致癌症死亡的第三大原因。所有传统的肝癌治疗方法都充满了副作用和有限的疗效。因此，寻找针对肝细胞癌生长的潜在分子事件并干扰肝细胞癌发展的新型药物是很重要的。结果表明，癌基因FOXM1在肝细胞癌的发生发展中起重要作用，提示抑制FOXM1可能是治疗肝细胞癌的一种有前景的策略。噻唑类抗生素西奥霉素A和硫代链球菌素是本实验室鉴定的FOXM1的有效抑制剂和肝癌细胞的凋亡诱导剂。本研究的目的是研究西奥霉素A/硫代链球菌素的分子作用机制，并在小鼠肝癌模型上测试其体内疗效。噻唑类抗生素可能是很有前途的抗肝癌药物，因为它们会导致癌细胞死亡，但不会导致正常细胞死亡。完成我们的建议将使我们能够确定噻唑类抗生素是否适合进一步的临床开发。

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.