The extracellular matrix is an important regulatory component of tumor cell invasion and migration. Specifically, the alternatively spliced V region of fibronectin (FN) is important to these progresses since only FN miniproteins (V+H and V+H-) containing this region induce increased invasion and migration of squamous cell carcinoma (SCC) cells in vitro. In contrast, primary normal keratinocytes and fibroblasts undergo apoptosis when treated with the V+H-FN protein. In fibroblasts, this mechanism is mediated by chondroitin sulfate proteoglycans, possibly by the alpha 4 integrin, by a caspase cascade involving caspase-1 and -3, by alterations in p53 and c-myc, and by a concomitant decrease in pp125 FAK. These data suggest that tumorigenicity has enabled SCC cells to bypass the apoptotic pathway and instead take on an invasive and migratory phenotype in response to the V+H- protein. It is hypothesized that SCC cells undergo increased migratory phenotype in response to the V+H- protein. It is hypothesized that SCC cells undergo increased invasion and migration in response to the alternatively spliced V region of FN via cell surface proteoglycan and integrin receptors, which initiate a signal transduction pathway that differs from that in primary non- transformed receptors, which initiate a signal transduction pathway that differs from that in primary non-surface receptor(s) involved in mediating increased migration and invasion induced by the V-containing FN fragments. Specifically, determine whether condroitin sulfate proteoglycans and the alpha4 integrin are involved in this mechanism of invasion and migration, since these receptors regulate the apoptotic pathway triggered by the V-containing FN fragment in fibroblasts. (2) Examine the SCC cell signaling response involved in mediating increased migration and invasion induced by the V-containing FN fragments. Specifically, determine whether p53 and c-myc are modulated as in the primary cells. These studies will help explain some of the basic mechanisms underlying the cell-matrix interactions and signaling mechanism that regulate tumor cell biology. In addition, since squamous cell carcinoma is the most common type of malignant oral neoplasm, accounting for a major portion of deaths related to oral cancer, these studies may provide potentially useful avenues for therapeutic intervention.
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