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

描述(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)可以进展为威胁生命的转移，因此寻找一种能够特异性抑制BC侵袭和转移的天然化合物对于潜在地降低这种疾病的死亡率具有极其重要的意义。异黄体素(Isorhapontigenin，ISO)是二苯乙烯的一种新的衍生物，是从中国用来治疗胆囊炎的一种中草药中分离出来的，其分子机制尚不清楚。因此，这项建议的目标是确定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)在所有被测试的人类侵袭性BC组织中都高度表达，但在所有邻近的正常膀胱组织中几乎检测不到XIAP的表达，并且在P53-/-/PRB-/-小鼠的BBN诱导的侵袭性BC组织中，XIAP的表达水平也显著高于野生型小鼠和致癌RAS诱导的低级别BCS。我们还发现来自HGIBC的培养的人BC细胞的XIAP显著高于来自低级别乳头状膀胱肿瘤(LGPBT)的细胞。此外，我们还发现ISO处理BC细胞可抑制HGIBC T24T细胞的迁移和侵袭，并在转录水平上特异性地抑制Sp-1反式激活和XIAP的下调，而不影响细胞的增殖。因此，我们推测ISO是一种通过下调Sp-1/XIAP途径抑制BC体外侵袭和体内BC侵袭和转移的有效药物。我们将通过以下目的对此进行验证：1：验证ISO下调XIAP是其抑制BBN诱导的BC形成的假说，该假说在缺乏P53和pRb的小鼠中起作用；2：评估SP-1是ISO下调XIAP在体内外BC形成的主要靶点的假设；3：确定ISO在体外和体内抑制BC形成的分子机制。该提议的成功将有助于我们理解ISO化合物抗癌作用的分子机制(S)。这一新的发现将为设计更有效的利用ISO的策略或合成其他用于治疗BCS和其他癌症的新型构象受限衍生物提供有价值的信息。考虑到BC是最常见的恶性肿瘤，每年在全球范围内造成33.6万新病例和13.2万人死亡，这些研究反过来应该有助于改善BCS患者的临床结果。

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.