Function of p53 and its target genes

p53及其靶基因的功能

基本信息

批准号：
12213115
负责人：
TOKINO Takashi
金额：
$ 42.82万
依托单位：
Sapporo Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2004
项目状态：
已结题

项目摘要

1. Novel p53-target genes : Tumor suppressor p53 is a transcription factor that induces growth arrest and/or apoptosis in response to cellular stress. To identify novel p53-inducible genes, we compared the expression of genes in normal mouse embryo fibroblasts to p53-null cells by cDNA representational difference analysis (RDA). We have identified that expression of endogenous SCN3B (sodium channel subunit beta 3) and OPN (osteopontin) are upregulated in mouse embryonic fibroblasts by DNA damage in a p53-dependent manner. The p53-directed regulation of OPN expression suggests a novel model of p53 participation in immunosurveillance, involving interaction with the host immune system to prevent damaged cells from undergoing malignant transformation. The results presented above also suggest that SCN3B mediates a p53-dependent apoptotic pathway and may be a candidate for gene therapy combined with anticancer drugs.2. Biological functions of the p53 family member genes : p63 and p73 were re … More cently identified as members of the p53 gene family. In contrast to p53 however, p63 and p73 are rarely mutated in human cancers. To determine how p63 and p73 are involved in carcinogenesis and normal development, we attempted to identify target genes that are specifically regulated by p63 and/or p73 but not p53. We identified the JAG1 and JAG2 genes, encoding ligands for the Notch receptors, and the PEDF gene are direct target of p63 and p73. We also found that IL4 receptor alpha is upregulated by p73. These findings show an association between the p53 family genes and Notch signaling and suggest a potential molecular mechanism for the involvement of the p53 family genes in normal development. Our data also suggest that IL-4Ralpha could mediate, in part, certain immune responses and p73-dependent cell death.3. Adenovirus-mediated transfer of the p53 family genes, p73 and p63 induces cell cycle arrest and apoptosis in human cancer cell lines : p53 gene therapy is being tested clinically for the treatment of human cancer, however, some cancer models (in vivo and in vitro) are resistant to p53. To explore the potential use of two p53 homologues, p73 and p63, in cancer gene therapy, we introduced p53, p73 and p63 into colorectal cancer cell lines via adenoviral vectors, and compared their effects on cell growth. Among 10 cell lines tested, six cell lines displayed a similar response following transduction of p53, p73beta or p63gamma ; two lines underwent cell-cycle arrest, three lines exhibited apoptosis and one line showed no-effect following transduction. The effect on cell-cycle progression was variable in the other four cell lines. Interestingly, three cell lines were resistant to p53-mediated apoptosis, including two lines having endogenous wild-type p53 alleles, but underwent apoptosis after transduction of p73beta or p63gamma. Transduction of p73beta and p63gamma also reduced the tumorigenicity of two colorectal cancer cells in vivo. These results suggest that adenovirus-mediated p73beta and p63gamma transfer are potential novel approaches for the treatment of human cancers, particularly for tumors that are resistant to p53 gene therapy. Less

1. 新型 p53 靶基因：肿瘤抑制因子 p53 是一种转录因子，可响应细胞应激诱导生长停滞和/或凋亡。为了鉴定新型 p53 诱导基因，我们将正常小鼠胚胎成纤维细胞中的基因表达与 p53 进行了比较。 -通过 cDNA 代表性差异分析 (RDA)，我们已经鉴定了空细胞内源性 SCN3B（钠通道亚基 β 3）和 OPN（骨桥蛋白）的表达。 p53 介导的 OPN 表达调节在小鼠胚胎成纤维细胞中通过 DNA 损伤而上调，这表明 p53 参与免疫监视的新模型，涉及与宿主免疫系统的相互作用，以防止受损细胞发生恶性转化。上述结果也表明SCN3B介导p53依赖性细胞凋亡途径，可能是与抗癌药物联合进行基因治疗的候选者。 2． p53 家族成员基因：p63 和 p73 最近被鉴定为 p53 基因家族的成员，但与 p53 相比，p63 和 p73 在人类癌症中很少发生突变。在开发过程中，我们试图鉴定受 p63 和/或 p73 而不是 p53 特异性调节的靶基因，我们鉴定了编码配体的 JAG1 和 JAG2 基因。 Notch 受体和 PEDF 基因是 p63 和 p73 的直接靶标。我们还发现 p73 上调 IL4 受体 α。这些发现表明 p53 家族基因与 Notch 信号传导之间存在关联，并提出了参与其中的潜在分子机制。我们的数据还表明，IL-4Rα 可以部分介导某些免疫反应和 p73 依赖性细胞死亡。 3．家族基因、p73 和 p63 在人类癌细胞系中诱导细胞周期停滞和细胞凋亡：p53 基因疗法正在临床测试用于治疗人类癌症，然而，一些癌症模型（体内和体外）对 p53 具有抗性。为了探索两种p53同源物p73和p63在癌症基因治疗中的潜在用途，我们通过腺病毒载体将p53、p73和p63引入结直肠癌细胞系，并比较它们的在测试的 10 个细胞系中，6 个细胞系在转导 p53、p73beta 或 p63gamma 后表现出类似的反应；2 个细胞系出现细胞周期停滞，3 个细胞系显示细胞凋亡，1 个细胞系在转导后未显示任何影响。其他四种细胞系对细胞周期进程的影响各不相同，这表明，三种细胞系对 p53 介导的细胞凋亡具有抵抗力，其中两种细胞系具有内源性野生型 p53 等位基因，但在转导后发生细胞凋亡。 p73beta 或 p63gamma。p73beta 和 p63gamma 的转导也降低了两种结肠直肠癌细胞的体内致瘤性。这些结果表明，腺病毒介导的 p73beta 和 p63gamma 转移是治疗人类癌症的潜在新方法，特别是对于具有抗性的肿瘤。 p53基因治疗较少。