Targeting CDK4 in TGF-B Inactivated Gastrointestinal Cancers

最近的研究表明，转化生长因子-IS通过在G1期阻断细胞周期进程来抑制细胞增殖 它是细胞周期的一个阶段，因此被认为是一种肿瘤抑制蛋白。大多数人类癌症 似乎已经失去了对转化生长因子-U的生长抑制反应。我们的初步研究表明， 转化生长因子-I3信号失活的癌症表达高水平的细胞周期蛋白D1和CDK4，提示 这些蛋白的失控表达可能有助于这些肿瘤的发展。 已证实的一种用于某些癌症治疗方案的CDK抑制剂--黄曲霉素醇可以抑制 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。 在临床试验中由这种药物引起的。根据这些观察结果，我们筛选出了一种化合物 特异性抑制CDK-4的激酶抑制剂文库和分离的两个新分子(ON55290和ON55290 ON27900)具有CDK4抑制活性。在这一应用中，我们建议进行临床前 测试这些分子在胃肠道癌症治疗中的有效性的研究。 这项建议的目的是： 1.进一步验证CDK4在Elf‘’，Elf/~：Smad3+/-肿瘤模型系统中的作用。 CDK4+/V Bf1‘，CDK4+/~：ELF/Elf’-Smads^和CDK4+A；Elf？/Elf：Smad4+/-小鼠的肿瘤发生率。 2.(A)扩充化学文库，以了解化合物的构效关系 CDK4抑制剂和(B)ON55290和ON27900对CDK4的抑制进行详细的动力学分析 以获得关于这些化合物引起其抑制作用的机制的关键信息 CDK4。 3.确定ON55290和ON27900导致生长停滞和 人胃肠道癌细胞死亡。4.评估候选药物的安全性和药代动力学 在转化生长因子-f3失活状态下发展的胃肠道癌症动物模型中的药物。

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.