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

项目概要/摘要 该提案重点关注细胞分裂周期 7 相关蛋白 (CDC7)。该提案的总体目标是 测试 CDC7 激酶的抑制是否可能代表一种强有力的治疗策略 携带突变 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，通过物理作用激活 与调节亚基 DBF4 或 DRF1 相互作用。 DRF1 代表 CDC7 的激活剂 胚胎发生，而 DBF4 主要在体细胞分裂过程中发挥作用。 DBF4-CDC7 激酶 在 G1 期末被激活并使复制前复合物的成分磷酸化 （pre-RCs），从而触发细胞进入DNA合成阶段（S期）。据报道，CDC7 对于所有研究的生物体（从酵母到人类）的细胞分裂至关重要。多份报告记录了 具有 p53 突变的人类癌细胞对 CDC7 抑制特别敏感。 CDC7蛋白的耗尽， 或抑制 p53 突变癌细胞中的激酶活性可引发肿瘤细胞凋亡。对于 由于这些原因，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 在肿瘤发生中。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。为了规避这个限制，并 在研究 CDC7 功能的后期阶段，我们的实验室开发了一种新型小鼠品系，可以让我们关闭 CDC7 蛋白。这些小鼠和源自它们的细胞为我们提供了研究分子功能的工具 疾病预防控制中心7。在目标 1 中，我们将研究 CDC7 在正常非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颖的、以前未预料到的细胞分子机制 部门，这将在本目标中进行审查。在目标 2 中，我们将分析 CDC7 在人类中的其他功能 CDC7可能在肿瘤发生中发挥重要作用。在目标 3 中，我们将使用鼠标 忠实再现 p53 突变三阴性乳腺癌的模型。使用这些小鼠，我们将测试 肿瘤发生过程中对 CDC7 的需求。该提案的预期总体影响是它将改变 我们对细胞分裂机制的理解将阐明 CDC7 在肿瘤发生中的新作用， 并将测试针对 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.