The Role Of TKS5 SH3 Domains In Invadopodia Development And Activity

One mechanism by which cancer cells metastasize is through the formation of actin-rich structures called invadopodia. Tks5 is a Src tyrosine kinase substrate and scaffolding protein necessary for invadopodia formation and associated extracellular matrix-remodeling activity. The purpose of this study is to appreciate how the five, protein binding SH3 domains of Tks5 impact its function. Here, Tks5 SH3 domain mutants were introduced into cancer cells to study invadopodia development and activity. Mutant Tks5 constructs were introduced into LNCaP cells to study effects on extracellular matrix degradation based on a microscopic in situ zymography assay. Then, mutant Tks5 constructs were introduced into invadopodia-competent Src-transformed fibroblasts in order to observe their localization by immunofluorescent microscopy. Tks5 constructs with mutations in any of the first three SH3 domains result in an enhancement of invadopodia activity in LNCaP cells while mis-localizing to lipid-rich endosomes in Src-transformed cells and inhibiting their ability to form invadopodia. The loss of invadopodia formation was attributed to a retention of Src kinase in perinuclear endosomes. Current experimentation is focused on elucidating the mechanisms behind the observed results with particular focus on the putative intra and intermolecular Tks5 interactions that would drive the invasive/metastatic behavior of cancer cells.