Mechanisms underlying therapeutic effect of a new compound Isorhapontigenin (ISO)

描述（由申请人提供）：膀胱尿路上皮癌（或膀胱癌，BC）是西方世界最常见的癌症之一。由于高级别浸润性膀胱癌（HGIBC）可能发展为危及生命的转移，因此鉴定特异性抑制BC浸润和转移的天然化合物对于潜在降低这种疾病导致的死亡率非常重要。异甘草素（Isorhapontigenin，ISO）是一种新的二苯乙烯衍生物，从一种中药中分离得到，在中国用于治疗膀胱癌已有数百年的历史，但对其分子机制尚不清楚。因此，本提案的目标是确定ISO潜在的治疗效果和负责这种抗癌活性的分子机制。我们的初步研究发现，X连锁的凋亡抑制蛋白（XIAP）在所有检测的人类浸润性BC组织中极高表达，但在所有相邻的正常膀胱组织中几乎检测不到，在BBN诱导的p53-/-/pRb-/-小鼠的侵袭性BC组织中，XIAP表达水平也显著高于野生型小鼠和致癌Ras-/pRb-/-小鼠。导致低等级的BC。我们还发现，XIAP是显着较高的培养的人BC细胞来源于HGIBC比那些来自低级别乳头状膀胱肿瘤（LGPBT）。此外，我们发现用ISO处理BC细胞抑制HGIBC T24 T细胞的迁移和侵袭，伴随着在转录水平特异性抑制Sp-1反式激活和XIAP下调，而在5-10 μ M的剂量下不影响细胞增殖。因此，我们假设ISO是通过下调Sp-1/XIAP途径抑制BC体外侵袭和BC体内侵袭和转移的有效治疗剂。我们将用以下目的对此进行检验：1：检验ISO下调XIAP是其在缺乏p53和pRb的小鼠中抑制BBN诱导的BC形成的原因的假设; 2：评估SP-1是体外和体内BC中ISO下调XIAP的主要靶标的假设; 3：明确ISO在体内外抑制BC发生的分子机制。建议的成功将有助我们了解ISO化合物的抗癌作用的分子机制。这一新的发现将为设计更有效的策略以利用ISO或合成用于治疗BC和其他癌症的其他新的构象约束衍生物提供有价值的信息。考虑到BC是最常见的恶性肿瘤，每年全球有336，000例新发病例和132，000例死亡，这些研究反过来应该有助于改善BC患者的临床结局。

DESCRIPTION (provided by applicant): Urothelial carcinoma of the bladder (or bladder cancer, BC) is one of the most common cancers in the Western world. Because high-grade invasive bladder cancers (HGIBC) can progress to life threatening metastases, identifying a natural compound that specifically inhibits BC invasion and metastasis is of tremendous importance for potentially reducing mortality as a result of this disease. Isorhapontigenin (ISO) i a new derivative of stilbene, and isolated from a Chinese herb that has been used in China for treatment of BCs for hundreds of years without understanding of molecular mechanisms. Thus, the goal of this proposal is to determine the ISO potential therapeutic effect and the molecular mechanisms responsible for this anti-cancer activity. Our preliminary studies found that the X-linked inhibitor of the apoptosis protein (XIAP) was extremely highly expressed in all of the human invasive BC tissues that were tested, but it was barely detectable in all adjacent normal bladder tissues, and that XIAP expression level was also markedly elevated in BBN-induced invasive BC tissues in p53-/-/pRb-/- mice as compared with that from wild-type mice and oncogenic Ras- induced low-grade BCs. We also found that XIAP was significantly higher in cultured human BC cells derived from HGIBC than from those derived from low-grade papillary bladder tumors (LGPBT). Moreover, we showed that treatment of BC cells with ISO inhibited HGIBC T24T cell migration and invasion, was accompanied with specific inhibition of Sp-1 transactivation and XIAP downregulation at the transcription level without affecting cell proliferation at doses of 5-10 ¿M. Thus, we hypothesize that ISO is an effective therapeutic agent for the inhibition of BC invasion in vitro and BC invasion and metastasis in vivo via downregulation of the Sp-1/XIAP pathway. We will test this with the following aims: 1: To test the hypothesis that XIAP downregulation by ISO is responsible for its inhibition of BBN-induced BC formation in the mice lacking both p53 and pRb; 2: To evaluate the hypothesis that SP-1 is a major target for ISO downregulation of XIAP in BC in vitro and in vivo; 3: To define the molecular mechanisms whereby ISO inhibits the BC development in vitro and in vivo. Success of the proposal will facilitate our understanding of the molecular mechanism(s) responsible for the anti-cancer effects of ISO compound. This novel finding will provide valuable information for the design of more effective strategies for utilization of ISO or for the synthesis of other novel conformation- constrained derivatives for the treatment of BCs and other cancers. Taken together with the fact that BC is the most common malignant tumors, responsible for 336,000 new cases and 132,000 deaths annually worldwide, the studies should in turn help improve the clinical outcome of patients with BCs.