Studies of Alternations of c-MET in SCLC

描述(申请人提供)：建议的项目将在Ravi Salgia博士的指导下进行，Ravi Salgia博士在小细胞肺癌的酪氨酸激酶、细胞骨架和侵袭/转移方面拥有丰富的专业知识。我的长期职业目标是成为一名独立的临床医生兼科学家，从事转化型癌症研究，专注于靶向治疗。我发现c-Met在小细胞肺癌中有表达和功能，有时还会发生突变。我有新的免疫组织化学发现，活化的磷酸化蛋氨酸优先定位于肿瘤侵袭前沿。在最近完成的小细胞肺癌c-Met突变分析中，我发现了c-Met的新的选择性剪接转录本和体细胞突变，特别是在SEMA结构域和邻近膜(JM)结构域。研究发现，JM突变改变了c-Met信号转导途径，增加了酪氨酸磷酸化，包括关键的粘着斑蛋白Paxlin。这被发现与JM突变增强的肿瘤形成和细胞运动/迁移有关。这些结果表明，JM-结构域在c-Met信号转导中具有独特的作用，对细胞骨架功能有显著影响。两种可用的特异性c-Met抑制剂(SU11274和PHA665752)的初步研究表明，有希望抑制小细胞肺癌的生存和运动。我现在的目标是进一步确定各种c-Met突变在小细胞肺癌中的功能意义，如生存、存活/凋亡和转化。C-Met突变对下游PI3K/Akt信号通路的影响将通过联合使用PI3K-激酶、IP/IB和PI3K抑制剂来确定。表达野生型或突变Met的细胞系将被建立并用于功能分析。将调查各种生物分析，如散布、移动/迁徙和入侵。利用针对焦点黏附蛋白的磷酸特异性抗体和延时视频显微镜，研究将集中在细胞骨架功能上。C-Met及其突变体的各种抑制剂在小细胞肺癌中的作用将进一步确定，旨在转化为新的靶向治疗药物。

DESCRIPTION (provided by applicant): The proposed project will be performed under the mentorship of Dr. Ravi Salgia, who has great expertise in the tyrosine kinases, cytoskeleton, and invasion/metastasis in SCLC. My long term career goal is to become an independent clinician-scientist in translational cancer research with focus on targeted therapeutics. I have found that c-Met is expressed, functional and sometimes mutated in SCLC. I have novel immunohistochemistry finding of the activated phospho-Met localized preferentially at the tumor invasive front. In the recently completed c-Met mutational analysis in SCLC, I have identified novel alternatively spliced transcripts and somatic mutations of c-Met, particularly in the Sema domain and the juxtamembrane (JM) domain. The JM-mutations were found to alter c-Met signaling with increased tyrosine phosphorylation including the key focal adhesion protein paxillin. This was found correlating with enhanced tumorigenesis and cell motility/migration by the JM mutations. These results suggest a unique role of the JM-domain in c-Met signaling with dramatic effects in cytoskeletal functions. Preliminary studies with two available specific c-Met inhibitors (SU11274 and PHA665752) have shown promising inhibition of viability and motility of SCLC. I now aim to further determine the functional implications of the various c-Met mutations in SCLC, such as viability, survival/ apoptosis, and transformation. Effects of the c-Met mutations on the downstream PI3K/Akt signaling pathway would be determined with combinations of PI3K-kinase assay, IP/IB, and also PI3K inhibitors. Cell lines expressing wild-type or mutated Met would be established and utilized in functional analyses. Various biological assays, such as scattering, motility/migration, and invasion would be investigated. Utilizing phosphospecific antibodies against focal adhesion proteins, and time-lapse video-microscopy, studies would be focused on cytoskeletal functions. The role of various inhibitors of c-Met and its mutants in SCLC would be further defined aiming to translate into novel targeted-therapeutics.