A comparative approach of tumor associated inflammation in mammary cancer between humans and dogs

Infiltrating cells of the immune system are widely accepted to be generic constituents of tumor microenvironment. It has been well established that the development of mammary cancer, both in humans and dogs, is associated with alterations in numbers and functions of immune cells at the sites of tumor progression. These tumor infiltrating immune cells seems to exhibit exclusive phenotypic and functional characteristics and mammary cancer cells can take advantage of signaling molecules released by them. Cancer related inflammation has an important role in mammary carcinogenesis, contributing to the acquisition of core hallmark capabilities that allow cancer cells to survive, proliferate, and disseminate. Indeed, recent studies in human breast cancer and in canine mammary tumors have identified a growing list of signaling molecules released by inflammatory cells that serve as effectors of their tumor-promoting actions. These include the COX-2, the tumor growth factor EGF, the angiogenic growth factor VEGF, other proangiogenic factors and a large variety of chemokines and cytokines that amplify the inflammatory state. This review describes the intertwined signaling pathways shared by Tlymphocytic/macrophage infiltrates and important tissue biomarkers in both human and dog mammary carcinogenesis.The work was supported partially by the Strategic Research project Pest-OE/AGR/UI0772/2011 and the Research Project UID/AGR/04033/2013, by a Ph.D. scholarship SFRH/BD/ 78771/2011 financed by the Portuguese Foundation for Science and Technology (FCT), and in part by the Austrian Science Fund (FWF), SFB F4606-B28, to Erika Jensen Jarolim