title: Imaging and quantifying the dynamics of tumor-associated proteolysis.
abstract: The roles of proteases in cancer are dynamic. Furthermore, the roles or functions of any one protease may differ from one stage of cancer to another. Proteases from tumor-associated cells (e.g., fibroblasts, inflammatory cells, endothelial cells) as well as from tumor cells make important contributions to 'tumor proteolysis'. Many tumors exhibit increases in expression of proteases at the level of transcripts and protein; however, whether those proteases play causal roles in malignant progression is known for only a handful of proteases. What the critical substrate or substrates that are cleaved in vivo by any given protease is also known for only a few proteases. Therefore, the recent development of techniques and reagents for live cell imaging of protease activity, in conjunction with informed knowledge of critical natural substrates, should help to define protease functions. Here we describe live cell assays for imaging proteolysis, protocols for quantifying proteolysis and the use of such assays to follow the dynamics of proteolysis by tumor cells alone and tumor cells interacting with other cells found in the tumor microenvironment. In addition, we describe an in vitro model that recapitulates the architecture of the mammary gland, a model designed to determine the effects of dynamic interactions with the surrounding microenvironment on 'tumor proteolysis' and the respective contributions of various cell types to 'tumor proteolysis'. The assays and models described here could serve as screening platforms for the identification of proteolytic pathways that are potential therapeutic targets and for further development of technologies and imaging probes for in vivo use.
authors.affiliation: Department of Pharmacology, School of Medicine, Wayne State University, 540 E. Canfield, Detroit, MI 48201, USA.
authors.forename: Mansoureh
authors.initials: M
authors.lastname: Sameni
authors.forename: Dora
authors.initials: D
authors.lastname: Cavallo-Medved
authors.forename: Julie
authors.initials: J
authors.lastname: Dosescu
authors.forename: Christopher
authors.initials: C
authors.lastname: Jedeszko
authors.forename: Kamiar
authors.initials: K
authors.lastname: Moin
authors.forename: Stefanie R
authors.initials: SR
authors.lastname: Mullins
authors.forename: Mary B
authors.initials: MB
authors.lastname: Olive
authors.forename: Deborah
authors.initials: D
authors.lastname: Rudy
authors.forename: Bonnie F
authors.initials: BF
authors.lastname: Sloane
mesh_terms: D000818:Animals; D003952:Diagnostic Imaging; D006801:Humans; D009369:Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*
chemical_list: D010447:Peptide Hydrolases