Chemoresistance and Motility: Role of Mutant p53 and NF-kB2 in Cancer

描述（由申请人提供）：p53肿瘤抑制基因突变是人类癌症的常见事件。在大多数具有p53突变的人类癌中，突变蛋白过表达，表明存在维持表达的选择性优势。我们研究的长期目标是了解p53突变如何导致肿瘤发生。短期目标是检验以下假设：p53突变体在人类细胞中的表达解除了由NF-κ B 2控制的通路，NF-κ B 2是对化疗敏感性和肿瘤进展至关重要的特性。上述假设基于以下观察：与载体转染的细胞相比，表达突变型p53的H1299 p53-null人肺癌细胞在用常规化疗剂处理时显示出化疗抗性;然而，表达反式激活缺陷型突变体的细胞显著丧失了这种功能，这表明突变型p53的反式激活对于化疗抗性至关重要。许多具有突变型p53的肺癌和乳腺癌细胞系显示出依赖于p53水平的化学抗性，因为当p53水平降低时，化学抗性降低。p53突变体诱导许多涉及细胞生长、存活、侵袭、转移和血管生成的基因的表达。NF-kB 2是其中之一。导入NF-：B2特异性的短干扰RNA使这些细胞失去化疗抗性。对人肺癌标本的初步筛选显示p53突变和NF-kB 2过表达共存，这表明在临床上，存在一个具有p53突变和NF-kB 2过表达的患者亚组。我们的数据还表明，突变型p53表达增强细胞粘附，运动性，致瘤性和转移表型。具体目标如下：1. (a)确定突变型p53过表达是否导致肺癌中NF-κ B 2水平升高。(b)确定NF-κ B 2是否参与降低表达突变型p53的癌细胞的化疗敏感性。2.确定NF-：B2是否增强表达突变型p53的细胞的运动性。3.研究突变型p53上调NF-κ B 2表达的机制。4.利用质谱分析鉴定与GOF p53突变体特异性相互作用的因子。这项研究将调查癌症中常见的p53突变体与NF-：B2通路之间的关系。未来，具有p53突变的肿瘤可以针对NF-：B2、突变型p53及其许多潜在的靶基因。化疗耐药性和运动性：突变型p53和NF-：B2在癌症中的作用。公共卫生相关性：该应用基于肿瘤来源的p53突变体上调细胞培养物中NF-κ B 2表达的新观察。对人类肿瘤的初步检查也表明，具有p53突变的肺肿瘤具有较高的NF-：B2水平。我们还发现，突变型p53的表达诱导更高的运动性和表达它们的细胞的化学抗性。我们建议确定这种上调的分子机制，并找出如何与表达突变型p53的细胞的化学抗性和更高的运动性相关。从该研究获得的结果应导致鉴定共表达NFkB 2和突变型p53的肺肿瘤亚组，其可被NF-kB途径的抑制剂靶向以防止肿瘤进展。

DESCRIPTION (provided by applicant): Mutation in the p53 tumor suppressor gene is a common event in human cancer. In the majority of human carcinomas with p53 mutations the mutant protein is over-expressed suggesting the existence of a selective advantage to maintain expression. The long-term goal of our research is to understand how p53 mutations lead to oncogenesis. The short-term objective is to test the following hypothesis: Expression of p53 mutants in human cells deregulates pathways controlled by the NF-kB2, a property critically important for chemosensitivity and tumor progression. The above-mentioned hypothesis is based on the following observations: Compared to vector transfected cells, H1299 p53-null human lung carcinoma cells expressing mutant p53 showed chemo-resistance when treated with common chemotherapeutic agents; however, cells expressing transactivation deficient mutants lose this function significantly, suggesting that transactivation by mutant p53 is crucial for chemo-resistance. A number of lung and breast cancer cell line with mutant p53 show chemo-resistance that is dependent on the level of p53 as the chemo-resistance decreases when the p53 level is lowered. p53 mutants induced expression of a number of genes involved in cell growth, survival, invasion, metastasis and angiogenesis. NF-kB2 was among this group. Introduction of short interfering RNA specific for NF-:B2 made these cells lose chemo-resistance. A preliminary screen of human lung cancer specimens shows co-existing p53 mutation and over-expression of NF-kB2 suggesting that, in the clinic, there is a subset of patients with p53 mutation and NF-kB2 over-expression. Our data also indicate that mutant p53 expression enhances cell adhesion, motility, tumorigenicity and metastatic phenotype. The following are the specific aims: 1. (a) To determine whether mutant p53 over-expression leads to higher levels of NF-kB2 in lung cancer. (b) To determine whether NF-kB2 is involved in reducing chemosensitivity in cancer cells expressing mutant p53. 2. To determine whether NF-:B2 enhances motility of cells expressing mutant p53. 3. To determine the mechanism of NF-kB2 up-regulation by mutant p53. 4. To identify factors interacting specifically with GOF p53 mutants utilizing mass spectrometric analysis. The proposed research will investigate the relationship between p53 mutants commonly found in cancer and the NF-:B2 pathway. In future, tumors with p53 mutations can be targeted at NF-:B2, mutant p53 and many of their potential target genes. Chemoresistance and Motility: Role of Mutant p53 and NF-:B2 in Cancer. PUBLIC HEALTH RELEVANCE: This application is based on a novel observation that tumor-derived p53 mutants up-regulate NF-kB2 expression in cell culture. Preliminary examination of human tumors also indicates that lung tumors with p53 mutation have a higher NF-:B2 level. We also find that mutant p53 expression induces higher motility and chemo-resistance in cells expressing them. We propose to determine the molecular mechanism of this up- regulation and find out how that is related to chemo-resistance and higher motility of cells expressing mutant p53. Results obtained from this study should lead to identification of a subset of lung tumors co- expressing NFkB2 and mutant p53 that could be targeted by inhibitors of NF-kB pathway to prevent tumor progression.