CDC7 kinase in normal and cancer cells: potential implications for cancer treatment

项目摘要/摘要 这项提案主要关注细胞分裂周期7相关蛋白(CDC7)。这项提案的首要目标是 检测抑制CDC7激酶是否代表了一种有效的治疗策略 携带突变的P53蛋白的人类癌症。在我们的研究中，我们将利用人类癌细胞系以及 小鼠癌症模型。我们的工作可能会为癌症患者带来一种新的治疗方法，特别是 靶向p53突变的人类癌细胞。CDC7是一种细胞周期激酶，它通过一种物理的 与调节亚基DBF4或DRF1相互作用。DRF1代表CDC7的激活剂 DBF4主要在体细胞分裂过程中起作用。DBF4-CDC7激酶 在G1期结束时被激活，并使复制前复合体的组分磷酸化 (RCS前)，从而触发细胞进入DNA合成期(S期)。据报道，CDC7是 在所有被研究的生物中，从酵母到人类，对细胞分裂都是必不可少的。有几份报告记录了 具有突变的p53的人类癌细胞对CDC7抑制特别敏感。CDC7蛋白耗尽， 或在p53突变的癌细胞中抑制其激酶活性可触发肿瘤细胞的凋亡。为 出于这些原因，我们决定进一步研究CDC7蛋白及其在正常细胞增殖中的作用以及 在肿瘤发生方面。其他人之前的工作已经证实，CDC7基因敲除小鼠在 妊娠，从而排除了对成年生物体中CDC7的分析。为了绕过这一限制，并 在研究CDC7功能的后期，我们的实验室开发了一种新的小鼠品系，它允许我们关闭 CDC7蛋白。这些小鼠及其衍生的细胞为我们提供了研究小鼠的分子功能的工具。 CDC7。在目标1中，我们将研究CDC7在正常和未转化细胞的细胞分裂中的分子作用。 我们的初步结果表明存在一种新的、以前未曾预料到的细胞分子机制 这一点将在这一目标中加以审查。在目标2中，我们将分析CDC7在人类中的附加功能 癌细胞，CDC7可能通过其在肿瘤发生中发挥重要作用。在目标3中，我们将利用一只鼠标 这个模型忠实地概括了p53突变的三阴性乳腺癌。使用这些老鼠，我们将测试 肿瘤发生过程中对CDC7的要求。这项提议的预期总体影响是，它将发生变化 我们对细胞分裂调控机制的理解，将阐明CDC7在肿瘤发生中的新作用。 并将测试靶向CDC7在癌症治疗中的效用。

Project Summary/Abstract This proposal focuses on cell division cycle 7-related protein (CDC7). The overarching goal of this proposal is to test whether inhibition of CDC7 kinase might represent a powerful therapeutic strategy in treatment of human cancers carrying mutated p53 protein. In our study, we will utilize human cancer cell lines as well as a mouse cancer model. Our work may lead to a novel therapeutic approach for cancer patients, specifically targeting p53-mutated human cancer cells. CDC7 is a cell cycle kinase that is activated through a physical interaction with regulatory subunits, DBF4 or DRF1. DRF1 represents the activator of CDC7 during embryogenesis, while DBF4 functions mainly during divisions of somatic cells. The DBF4-CDC7 kinase becomes activated at the end of G1 phase and phosphorylates components of the pre-replication complexes (pre-RCs), thereby triggering entry of cells into DNA synthesis phase (S phase). CDC7 was reported to be essential for cell division in all organisms studied, from yeast to humans. Several reports documented that human cancer cells with mutated p53 are particularly sensitive to CDC7 inhibition. Depletion of CDC7 protein, or inhibition of its kinase activity in p53-mutant cancer cells was shown to trigger tumor cell apoptosis. For these reasons, we decided to further study the CDC7 protein and its role in normal cell proliferation as well as in tumorigenesis. Previous work by others has established that CDC7 knockout mice die very early during gestation, thereby precluding analyses of CDC7 in an adult organism. To circumvent this limitation, and to study CDC7 function at later stages, our laboratory developed a novel mouse strain that allows us to turn off CDC7 protein. These mice and cells derived from them offer us tools to study the molecular functions of CDC7. In Aim 1, we will study the molecular role of CDC7 in cell division of normal, non-transformed cells. Our preliminary results indicate the presence of a novel, previously unanticipated molecular mechanism of cell division, which will be examined in this Aim. In Aim 2, we will analyze additional functions of CDC7 in human cancer cells, through which CDC7 may play important roles in tumorigenesis. In Aim 3, we will utilize a mouse model that faithfully recapitulates p53-mutant triple-negative breast cancers. Using these mice, we will test the requirement for CDC7 during tumorigenesis. The expected overall impact of this proposal is that it will change our understanding of mechanisms governing cell division, will elucidate novel roles of CDC7 in tumorigenesis, and will test the utility of targeting CDC7 in cancer treatment.