Role of Paxillin in Lung Cancer

描述（申请人提供）：肺癌是一种毁灭性的疾病，总体生存率很低。为了对这种疾病产生显著影响，必须确定新的目标和机制。肺癌的一个特征是细胞运动、迁移、侵袭和早期转移到淋巴结和其他器官。细胞骨架，特别是基于肌动蛋白的细胞骨架，本质上参与了肺癌的这些生物学功能。我们之前已经表明，局灶黏附受到各种癌基因转化的显著影响，特别是在肺癌中。特别是，68 kDa的局灶黏附蛋白paxillin在非小细胞肺癌（NSCLC）中发生显著改变（过表达并通过磷酸化激活）。在初步数据中，我们首次发现在非小细胞肺癌中存在paxillin基因的体细胞突变。例如，在大细胞癌中，突变频率高达18%。肺癌的不同组织学的突变频率存在差异。突变定位在LD结构域（对结合其他分子如FAK很重要）和LIM结构域（锌指结构域，对肌动蛋白结合很重要）之间。此外，非裔美国人、白种人和台湾人肺癌样本的paxillin基因突变也存在差异。paxillin最常见的突变是A127T，它可以提高肺癌细胞的存活率、肿瘤在体内的生长以及促进血管生成。利用二维PAGE，与野生型paxillin相比，突变体A127T也导致H522 NSCLC细胞中的差异蛋白表达。我们也发现了一个非小细胞肺癌的亚群有paxillin基因扩增。在肺癌中，帕罗西林在酪氨酸激酶c-Met受体激活的反应中也被磷酸化。有趣的是，在一些A127T突变的细胞系中，c-Met （R988C，近膜结构域）发生了突变。根据我们最近的发现，我们提出以下目标：确定paxillin在NSCLC中的表达、扩增和突变，并与人口学和临床因素、相关生物学标志物（如c-Met）和患者生存相关；2. 确定paxillin和突变paxillin在非小细胞肺癌中的生物学功能。此外，确定肺癌治疗抑制的潜力；3. 确定paxillin和c-Met在NSCLC生物学功能、血管生成和转移中的联合作用。在进行这些研究的过程中，我们将发现肺癌转化、转移和最终治疗的新机制。公共卫生相关性：肺癌是一种破坏性疾病，经常发生转移，对治疗反应差。我们已经确定细胞骨架蛋白paxillin在肺癌中起重要作用，特别是与细胞运动/迁移和最终转移有关。我们还发现paxillin基因可以在肺癌中选择性突变和/或扩增，从而使其更具侵袭性。我们的目标是研究帕罗西林在肺癌中的作用，并最终找到针对这种困难疾病的新疗法。

DESCRIPTION (provided by applicant): Lung cancer is a devastating illness with a poor overall survival. In order to dramatically impact on this disease, new targets and mechanisms have to be identified. One hallmark of lung cancer is enhanced cell motility, migration, invasion and early metastasis to lymph nodes and other organs. The cytoskeleton, especially actin-based, is intrinsically involved in these biological functions of lung cancer. We have previously shown that the focal adhesion is dramatically affected by transformation by various oncogenes, especially in lung cancer. In particular, the 68 kDa focal adhesion protein paxillin is dramatically altered (over-expressed and activated through phosphorylation) in non-small cell lung cancer (NSCLC). In preliminary data, we show for the first time that there are somatic mutations of the paxillin gene in NSCLC. In large cell carcinoma, for example, mutational frequency is up to 18%. There are differences in the mutational frequencies for the various histologies of lung cancer. The mutations were localized in between the LD domains (important for binding other molecules such as FAK) and in the LIM domains (zinc finger domains important in actin binding). Also, there were differences in paxillin gene mutations in lung cancer samples from African Americans, Caucasians, and Taiwanese. The most frequent mutation of paxillin, A127T, lead to enhanced lung cancer cell survival, tumor growth in vivo as well as enhanced angiogenesis. Using two-dimensional PAGE, the mutant A127T also led to differential protein expression in H522 NSCLC cells as compared to wild-type paxillin. We have also identified a subset of NSCLC that have amplification of the paxillin gene. Paxillin also was phosphorylated in response to activation of the receptor tyrosine kinase c-Met in lung cancer. Interestingly, in some cell lines with A127T mutation, there was a mutation of c-Met (R988C, juxtamembrane domain). Based on our most recent findings, we would propose the following aims: 1. Determine the expression, amplification, and mutations of paxillin in NSCLC and correlate with demographic and clinical factors, pertinent biological markers (such as c-Met) and patient survival; 2. Determine the biological functions of paxillin and mutated paxillin in NSCLC. Also, determine the potential for therapeutic inhibition in lung cancer; 3. Determine the combined role of paxillin and c-Met in NSCLC biological functions, angiogenesis and metastasis. In performing these studies, we will have arrived at novel mechanisms for transformation, metastasis and ultimately therapy against lung cancer. PUBLIC HEALTH RELEVANCE: Lung cancer is a devastating illness with frequent metastases and poor response to therapy. We have determined that the cytoskeletal protein paxillin plays an important role in lung cancer, especially as related to cell motility/migration with ultimate metastasis. We have also identified that paxillin gene can be selectively mutated and/or amplified in lung cancer and thereby make them more aggressive. Our goal is to study the role of paxillin in lung cancer and ultimately arrive at novel therapy against this difficult disease.