This is a proposal to investigate the molecular mechanisms underlying tumor cell invasion. Acquistion ofinvasive potential confers on tumor cells the ability to detach from the primary tumor and spread to distalsites. Using an invasive melanoma cell line as a model system, we have found that the small GTP-bindingprotein, ARF6, regulates cell invasion. In recent years, ARF6 has emerged as an important signalingmolecule and has been shown to regulate endosome cycling, and actin remodeling in a variety of cell types,both of which can impinge on the acquisition of cell migratory/invasive potential. Our studies demonstratethat ARF6 activation is linked to the activation of ERK via a signaling pathway that appears to be essentialfor cell invasion. Silencing of ARF6 by siRNAs or expression of an ARF6 dominant negative mutantabolishes invasion in cell-based in vitro assays. We have also shown that activation of endogenous ARF6increases in response to physiological stimuli that stimulate tumor cell invasion. In this application, we aim toinvestigate the mechanisms by which ARF6 regulates cell invasion. Based on preliminary findings, wehypothesize that ARF6 activation promotes tumor cell invasion at least in part, by regulating (1) thetrafficking of metalloproteases and (2) cytoskeletal remodeling required for invadopodia formation. By usingcell biological, molecular and biochemical approaches in both, cell and animal model systems, we willinvestigate the role of ARF6 in tumor cell invasion. We propose three specific aims.
In aim 1, we willinvestigate the role of ARF6 in the regulation of protease traffic by examining its regulation of MT1-MMPtraffic and the release of proteases from the cell surface.
In aim 2, we will elucidate the signal transductionpathway linking ARF6 to Rac1 activation during cell invasion and ask if invadopodia formation is importantfor protease secretion.
In aim 3, we will investigate the role of the ARF6 GTPase cycle in melanoma cellinvasion in vivo using a mouse model system. We believe that the information gained from investigationswill provide new insights into the regulation of protease trafficking, a relatively understudied area of cancerbiology, and will broaden existing knowledge on the molecular changes that occur during tumor progression.It is hoped that these findings will ultimately aid in the design of new strategies for diagnostic and/ortherapeutic intervention of cancer progression.
| Muralidharan-Chari, Vandhana; Clancy, James W; Sedgwick, Alanna et al. (2010) Microvesicles: mediators of extracellular communication during cancer progression. J Cell Sci 123:1603-11 |
| Muralidharan-Chari, Vandhana; Hoover, Holly; Clancy, James et al. (2009) ADP-ribosylation factor 6 regulates tumorigenic and invasive properties in vivo. Cancer Res 69:2201-9 |
| Hu, Bo; Shi, Binhai; Jarzynka, Michael J et al. (2009) ADP-ribosylation factor 6 regulates glioma cell invasion through the IQ-domain GTPase-activating protein 1-Rac1-mediated pathway. Cancer Res 69:794-801 |
| Muralidharan-Chari, Vandhana; Clancy, James; Plou, Carolyn et al. (2009) ARF6-regulated shedding of tumor cell-derived plasma membrane microvesicles. Curr Biol 19:1875-85 |
