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

描述(申请人提供)：p53肿瘤抑制基因突变是人类癌症中的常见事件。在大多数带有p53突变的人类癌症中，突变蛋白过度表达，这表明存在选择性优势来维持表达。我们研究的长期目标是了解p53突变是如何导致肿瘤发生的。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核因子-KB2控制的通路的调控，这是一种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：与载体转染细胞相比，表达突变型p53的H1299人肺癌细胞在常用化疗药物作用下表现出化疗耐药；而表达反式激活缺陷突变体的细胞显著丧失这一功能，提示突变型p53的反式激活在化疗耐药中起关键作用。一些带有突变型p53的肺癌和乳腺癌细胞株表现出化疗耐药，这种耐药取决于p53水平，因为当p53水平降低时，化疗耐药降低。P53基因突变可诱导多种基因表达，参与细胞生长、存活、侵袭、转移和血管生成。核因子-KB2就是其中之一。导入针对核因子-B2的短干扰RNA使这些细胞失去了化疗耐药性。对人类肺癌标本的初步筛查显示，P53突变和NF-KB2的过度表达共存，这表明在临床上，存在P53突变和NF-KB2过度表达的患者亚群。我们的数据还表明，突变型P53的表达增强了细胞的粘附性、运动性、致瘤性和转移表型。具体目的如下：1.(A)确定突变型P53过度表达是否导致肺癌中核因子-KB2水平升高。(B)确定核因子-KB2是否参与降低表达突变型p53的癌细胞的化疗敏感性。2.确定核因子-B2是否增强表达突变型P53的细胞的运动能力。3.探讨突变型P53上调核因子-KB2表达的机制。4.利用质谱仪鉴定与GOF P53突变体特异性相互作用的因子。这项拟议的研究将调查癌症中常见的P53突变与NF-：B2途径之间的关系。未来，携带P53基因突变的肿瘤可以针对核因子-B2、突变型P53及其许多潜在的靶向基因。化疗耐药和动力：突变型p53和核因子-：B2在癌症中的作用公共卫生相关性：这一应用是基于一项新的观察结果，即肿瘤来源的p53突变上调了细胞培养中的核因子-KB2的表达。对人类肿瘤的初步检查也表明，带有p53突变的肺癌具有较高的NF-：B2水平。我们还发现，突变型P53的表达在表达它们的细胞中诱导更高的运动性和化疗耐药性。我们建议确定这种上调的分子机制，并找出这与表达突变p53的细胞的化疗耐药性和更高的运动性之间的关系。这项研究的结果应该会导致鉴定出一组共表达NFKB2和突变型p53的肺癌，它们可以被核因子-kB途径的抑制剂作为靶点来防止肿瘤的进展。

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.