Chemoprevention of tobacco carcinogen-induced bladder cancer

描述(由申请人提供)： 膀胱癌是第五大最常见的癌症；接触一次/二手烟是主要的致病因素。约80%的患者表现为局限于粘膜的浅表疾病。复发是常见的侵犯肌肉甚至远处转移的致命后果。膀胱癌的进展包括通过突变或表观遗传机制激活特定的癌基因和生长因子/趋化因子，如CXCL-1和/或肿瘤抑制基因(p53、视网膜母细胞瘤、BIM、p21、RASSF1A、RUNX3和p16INK4)的失活。在烟草致癌物介导的膀胱癌进展过程中，基因沉默的表观遗传机制占主导地位；据报道，至少有50个基因经历了表观遗传修饰。这种基因沉默的机制涉及到组蛋白的特定翻译后修饰，特别是组蛋白H3和H4。组蛋白H3、K9和K27三甲基化增加和组蛋白H4 K20三甲基化缺失是癌症中常见的异常现象。因此，能够逆转富含癌症的组蛋白修饰的药物不仅在治疗浸润性膀胱癌方面应该有效，而且在防止浅表性病变向侵袭性病变进展方面也是有效的。我们已经开发出一种名为LC-1的化合物，它在体内和体外都能抑制膀胱癌细胞的生长。这种药物最初是作为转录因子NF-B的抑制剂而开发的，它可以抑制膀胱癌细胞中依赖于NF-B的CXCL-1的表达。此外，LC-1降低了“坏”表观遗传调节因子的水平，如多梳蛋白EZH2、组蛋白脱乙酰酶HADC1和CtBP-1。此外，它还降低了组蛋白H3K9和K27的三甲基化水平，但增加了组蛋白H4K20的三甲基化水平。这些LC-1诱导的组蛋白修饰与组蛋白H3K9三甲基酶SUV39H1的表达降低和肿瘤抑制基因RUNX3、BIM和p21的表达增加有关。假设：LC-1是一种独特的药物，可以通过抑制核因子-β和逆转癌症相关的表观遗传学变化来防止膀胱癌的进展。目的：探讨LC-1对烟草致癌物诱导的小鼠和Wister大鼠膀胱癌的化学预防作用及其与p21、BIM(LC-1诱导型)、EZH2、VEGF、SUV39H1(LC-1抑制)的表达水平的关系。意义：我们的研究具有直接的翻译潜力，因为LC-1已经经过了几次毒性和药代动力学研究，目前正处于白血病的I期临床试验。一项成功的白血病试验可以立即转化为针对浅表膀胱病变患者的膀胱癌化学预防试验。

DESCRIPTION (provided by applicant): Bladder cancer is the fifth most prevalent cancer; primary/second-hand tobacco exposure is the major etiologic factor. ~80% of patients present with superficial disease confined to the mucosa. Recurrence is common with invasion into muscle or even distant metastasis with fatal consequences. Bladder cancer progression involves activation of specific oncogenes and growth factors/chemokines such as CXCL-1 and/or inactivation of tumor suppressor genes (p53, retinoblastoma, BIM, p21, RASSF1A, RUNX3, and p16INK4) through mutations or epigenetic mechanisms. Epigenetic mechanism of gene silencing is dominant during tobacco carcinogen mediated bladder cancer progression; at least 50 genes are reported to undergo epigenetic modification. This mechanism of gene silencing involves specific post-translational modifications of histones, particularly histones H3 and H4. Increased histone H3 K9 and K27 trimethylation and loss of histone H4 K20 trimethylation are common abnormalities in cancers. Therefore, drugs that can reverse cancer-enriched histone modifications should be effective in not only treating invasive bladder cancer but also in preventing progression from superficial to invasive lesion. We have developed a compound called LC-1, which inhibits bladder cancer cell growth both in vivo and in vitro. This drug was originally developed as an inhibitor of the transcription factor NF-?B and it inhibited NF-?B-dependent expression of CXCL-1 in bladder cancer cells. Additionally, LC-1 reduced the levels of "bad" epigenetic regulators such as polycomb protein EZH2, histone deacetylase HADC1, and CtBP-1. Furthermore, it reduced the levels of histone H3 K9 and K27 trimethylation but increased the levels of histone H4 K20 trimethylation. These LC-1 induced histone modifications correlated with reduced expression of the histone H3 K9 trimethylase SUV39h1 and increased expression of tumor suppressors RUNX3, BIM, and p21 in LC-1 treated cells. Hypothesis: LC-1 is a unique drug that can prevent bladder cancer progression by inhibiting NF-?B as well as reversing cancer-associated epigenetic changes. Specific aim: Investigate the chemopreventive activity of LC-1 in tobacco carcinogen-induced bladder cancer in established ICR mice and Wister rat models and relate chemopreventive activity with the expression levels of p21, BIM (LC-1 inducible), EZH2, VEGF, and SUV39h1 (LC-1 repressed). Significance: Our study has immediate translational potential because LC-1 has already gone through several toxicity and pharmacokinetic studies and is currently in phase I clinical trial for leukemia. A successful leukemia trial can be translated immediately to bladder cancer chemoprevention trial for patients with superficial bladder lesions.