Abstract
Chronic inflammation in the tumor microenvironment has a prominent role in carcinogenesis and benefits the proliferation and survival of malignant cells, promoting angiogenesis and metastasis. Mammary tumors are frequently infiltrated by a heterogeneous population of immune cells where T-lymphocytes have a great importance. Interestingly, similar inflammatory cell infiltrates, cytokine and chemokine expression in humans and canine mammary tumors were recently described. However, in both species, despite all the scientific evidences that appoint for a significant role of T-lymphocytes, a definitive conclusion concerning the effectiveness of T-cell dependent immune mechanisms has not been achieved yet. In the present review, we describe similarities between human breast cancer and canine mammary tumors regarding tumor T-lymphocyte infiltration, such as relationship of TILs and mammary tumors malignancy, association of ratio CD4+/ CD8+ T-cells with low survival rates, promotion of tumor progression by Th2 cells actions, and association of great amounts of Treg cells with poor prognostic factors. This apparent parallelism together with the fact that dogs develop spontaneous tumors in the context of a natural immune system highlight the dog as a possible useful biological model for studies in human breast cancer immunology.
Highlights
The mammalian immune system comprises a coordinated and finely controlled series of interactions involving cells and molecules and has an essential role on species survival and adaptation all over the years [1]
In respect to the lymphocyte dysfunction that seems to be present in cancer patients, a tumor-directed immune response involving cytotoxic CD8+ T-cells, T helper 1 (Th1) cells, and natural killer (NK) cells appears to protect against tumor development and progression
On the contrary, showed that the increased number of Foxp3 Treg cells was significantly correlated with lymph node metastasis and immunopositivity for Ki-67, which indicates a probable relationship with a worse prognosis. [70]
Summary
Maria Isabel Carvalho, Isabel Pires, Justina Prada, and Felisbina L. We describe similarities between human breast cancer and canine mammary tumors regarding tumor T-lymphocyte infiltration, such as relationship of TILs and mammary tumors malignancy, association of ratio CD4+/ CD8+ T-cells with low survival rates, promotion of tumor progression by Th2 cells actions, and association of great amounts of Treg cells with poor prognostic factors. This apparent parallelism together with the fact that dogs develop spontaneous tumors in the context of a natural immune system highlight the dog as a possible useful biological model for studies in human breast cancer immunology
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