Several lines of evidence, however, show that all neoplasms, not just those arising on the background of chronic inflammation, thrive with inflammatory cell stimuli. Indeed, many times the tumor elicited immune response is unable to eliminate a rapidly growing population of cells that is always one step ahead due to the natural selection advantage. Instead, it shapes the tumor stroma in favor of cancer cell survival and expansion
in a manner similar to that observed in tissue remodeling and repair , ,  and . In that sense, the view of cancer as “a wound that does not heal”  has been further solidified. Consequently, key regulators of wound healing, such as immune cells and proteases, are now recognized RG7422 nmr as fundamental rather than secondary players in neoplasmatogenesis . One such regulator is urokinase-type plasminogen activator (uPA), a protease that has a dominant role in the proteolytic network and is primarily involved in fibrinolysis, tissue remodeling, and cell migration , ,  and . uPA catalyzes the conversion of plasminogen to plasmin and also activates other important proteases, including cathepsin B and matrix metalloproteinases. The targets of uPA in turn activate an array of proteins with a broad spectrum of biologic activities  and . In the tumor microenvironment, the complex cascades initiated
by uPA EPZ015666 order promote tumor progression. First, they facilitate neoplastic cell invasion, motility, and metastasis by degrading epithelial basement
membranes and the extracellular matrix. Second, they support tumor growth by stroma remodeling and angiogenesis. Finally, they are involved in proliferating and antiapoptotic tumor cell signaling , , , ,  and . These facts, supported by many studies in both animal models , , , ,  and  and humans  and , have placed uPA among the tumor promoting molecules with emerging importance. To date, uPA is considered as a poor prognosis factor and a potential therapeutic target for most types of cancer including colorectal cancer ,  and . Transforming growth factor–β1 Megestrol Acetate (TGF-β1) is one of the most important factors activated by the uPA-generated plasmin  and . TGF-β1 is ubiquitously produced by a variety of cells and excreted in the extracellular matrix in a latent form. The cleavage of this form by plasmin results in the production of the biologically active TGF-β1 , which has been shown to act as a tumor suppressor in the early stages of tumor development and as a major regulator of immune events in the tumor microenvironment  and . As with the corruption of normal TGF-β1 signaling pathways at the gene level  and , the lack of extracellular active TGF-β1 protein may also increase the risk of cancer initiation. Following this reasoning, we hypothesized that uPA and TGF-β1 may have an interlinked tumor-suppressive function.