Targeting CDK4 in TGF-B Inactivated Gastrointestinal Cancers

最近的研究表明，TGF-1 S通过阻断细胞周期的G1期进展来抑制细胞增殖 因此，被认为是一种肿瘤抑制蛋白。大多数人类癌症 似乎已经失去了对TGF-β 1的生长抑制反应。我们的初步研究表明前肠 TGF-13信号转导失活的癌症表达高水平的细胞周期蛋白D1和CDK 4水平，提示 这些蛋白质的表达失调可能有助于这些肿瘤的发展。 已知Flavopiridol是一种用于某些癌症治疗方案的已确立的Cdk抑制剂， 大多数已知的CDK，特别是针对CDK 7、8和9的CDK，被认为是毒副作用的主要原因 在临床试验中发现了这种药物根据这些观察，我们筛选出一种化合物 用于CDK-4特异性抑制的激酶抑制剂文库，并分离了两种新分子（ON55290和 ON 27900），其表现出CDK 4抑制活性。在本申请中，我们建议进行临床前 研究来测试这些分子在胃肠道癌症治疗中的有用性。 该提案的目的是： 1.为了进一步验证CDK 4在Elf +/-、Elf +/-：Smad 3 +/-肿瘤模型系统中的作用， CDK 4 +/V Bf 1-、CDK 4 +/-：Elf/Elf '-Smad 5-和CDK 4 +A; Elf/Elf：Smad 4 +/-小鼠中的肿瘤发病率。 2. (a)为了扩大化学库，努力了解结构活性关系（SAR）的 CDK 4抑制剂和（B）进行ON 55290和ON 27900对CDK 4抑制的详细动力学分析 以获得这些化合物引起其抑制作用的机制的关键信息， CDK4. 3.为了确定ON 55290和ON 27900引起生长停滞的分子机制， 人胃肠道癌细胞的死亡。4.评估候选药物的安全性和药代动力学 在TGF-f3失活状态下发展的胃肠癌动物模型中的药物。

Recent studies have shown that TGF-IS inhibits cell proliferation by blocking cell cycle progression at the G1 phase of the cell cycle and hence, is thought to function as a tumor suppressor protein. Most human cancers appear to have lost their growth-inhibitory response to TGF-U. Our preliminary studies show that foregut cancers with inactivation of TGF-I3 signaling express high levels of cyclin D1 and CDK4 levels, suggesting that the deregulated expression of these proteins may contribute to the development of these tumors. Flavopiridol, an established Cdk inhibitor used in treatment protocols for certain cancers, is known to inhibit most known CDKs especially against CDKs 7, 8 and 9, is thought to be largely responsible for the toxic sideeffects caused by this drug in clinical trials. In light of these observations, we have screened a compound library of kinase inhibitors for CDK-4 specific inhibition and isolated two novel molecules (ON55290 and ON27900) which exhibit CDK4 inhibitory activity. In this application, we propose to carry out pre-clinical studies to test the usefulness of these molecules in gastrointestinal cancer therapy. The aims of the proposal are: 1. To further validate the role of CDK4 in Elf'', Elf/~:Smad3+/- tumor model system through evaluation of tumor incidence in CDK4+/V Bf1', CDK4+/~: Elf/Elf'-SmadS^ and CDK4+A; Elf¿/Elf:Smad4+/- mice. 2. (a) To expand the chemical library in an effort to understand the structure-activity relationship (SAR) of CDK4 inhibitors and (b) to conduct a detailed kinetic analysis of CDK4 inhibition by ON55290 and ON27900 to gain critical information on the mechanisms by which these compounds elicit their inhibitory effects on CDK4. 3. To determine the molecular mechanisms by which ON55290 and ON27900 bring about growth arrest and death of human gastrointestinal cancer cells. 4. To assess the safety and pharmacokinetics of the candidate drug in animal models of gastrointestinal cancers that develop in the TGF-f3 inactivated state.