MOLECULAR MECHANISM OF CELL CYCLE ARREST BY APIGENIN

描述：芹菜素是一种植物类黄酮， 具有显著的化学预防活性， 诱导和紫外线诱导的小鼠皮肤癌 模型虽然芹菜素显示出作为化学预防剂的前景， 关于其作用的分子机制知之甚少。的 研究人员的初步结果表明， 培养的角质形成细胞产生大量的G2/M细胞周期停滞， 抑制细胞周期蛋白依赖性激酶p34 cdc 2激酶活性 其调节哺乳动物细胞中的G2/M转换。额外 实验表明，芹菜素对稳态无影响 p34 cdc 2激酶的蛋白水平，但可能影响p34 cdc 2 磷酸化状态。在本申请中，研究者 我建议测试芹菜素作为化学预防剂的假设， 通过抑制细胞周期而诱导细胞周期停滞在G2/M期的皮肤中的药物 p34 cdc 2激酶是细胞周期蛋白依赖性激酶， 哺乳动物细胞中的G2/M转换。以下目标将测试 这一假设在体外和体内，在表皮细胞， 肿瘤发生的各个阶段：（1）目的1将调查是否 芹菜素通过影响角质形成细胞的磷酸化而将角质形成细胞阻滞在G2/M期 p34 cdc 2激酶的状态，从而抑制其活性。(2)目标2 将研究芹菜素是否通过作用于G2/M期细胞， 细胞周期蛋白B的水平，通过（a）抑制细胞周期蛋白B的积累， G2期细胞周期蛋白B，（B）抑制细胞周期蛋白B的结合 与细胞周期蛋白依赖性激酶p34 cdc 2结合，或（c）促进细胞周期蛋白依赖性激酶p34 cdc 2结合， 细胞周期蛋白抑制剂与细胞周期蛋白/细胞周期蛋白依赖性 激酶复合物(3)目标#3将研究芹菜素是否能够 诱导角质形成细胞系在不同阶段的G2/M期阻滞 肿瘤的发生。(4)目标#4将采用UV-B致癌作用 在SKH-1小鼠模型中检查芹菜素治疗小鼠皮肤是否 可以抑制体内皮肤肿瘤细胞的生长， 存在肿瘤细胞。

DESCRIPTION: Apigenin is a plant flavonoid which has been shown to possess significant chemopreventive activity in inhibiting chemically- induced and ultraviolet light-induced skin cancer in the mouse skin model. Although apigenin shows promise as a chemopreventive agent, little is known about its molecular mechanism of action. The investigators' preliminary results indicate that apigenin treatment of cultured keratinocytes produces substantial G2/M cell cycle arrest and inhibition of p34cdc2 kinase activity, the cyclin dependent kinase which regulates G2/M transition in mammalian cells. Additional experiments indicated that apigenin had no effect on steady-state protein levels of p34cdc2 Kinase but may effect the p34cdc2 phosphorylation status. In the present application the investigators propose to test the hypothesis that apigenin acts as a chemopreventive agent in skin by inducing cell cycle arrest at G2/M via inhibition of p34cdc2 kinase, the cyclin dependent kinase which is responsible for the G2/M transition in mammalian cells. The following Aims will test this hypothesis both in vitro and in vivo, in epidermal cells at various stages of tumorigenesis: (1) Aim 1 will investigate whether apigenin arrest keratinocytes in G2/M by affecting the phosphorylation state of p34cdc2 kinase, thereby inhibiting its activity. (2) Aim #2 will study whether apigenin is arresting cells at G2/M by acting at the level of cyclin B, either by (a) inhibiting the accumulation of cyclin B during G2, (b) inhibiting the association of cyclin B with the cyclin-dependent kinase p34cdc2, or (c) promoting the association of a cyclin inhibitor with the cyclin/cyclin-dependent kinase complex. (3) Aim #3 will investigate whether apigenin is able to induce G2/M arrest in keratinocyte cell lines at various stages of tumorigenesis. (4) Aim #4 will employ the UV-B carcinogenesis model in SKH-1 mice to examine whether apigenin treatment of mouse skin can inhibit the growth of skin tumor cells in vivo even after foci of tumor cells are present.