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.
