No abstract

Tumour-associated macrophages (TAMs) have been implicated in carcinogenesis including an important role in angiogenesis. In this study, we describe the relationship between TAMs and angiogenesis in canine mammary tumours (CMT). Formalin-fixed paraffin-embedded CMT samples [(n = 128: malignant (n = 97) and benign (n = 31)] were submitted to immunohistochemical staining to detect MAC387, vascular endothelial growth factor VEGF and CD31 expression. A statistical analysis was carried out to assess possible associations with clinicopathological variables and biological markers of tumour angiogenesis. TAMs, detected by MAC387 expression, were significantly associated with malignant CMT (P < 0.001) and VEGF positive tumours (P = 0.002) and also associated with VEGF expression within malignant CMT (P = 0.043). Associations with clinicopathological variables were found between TAMs and the presence of infiltrative growth (P = 0.031), low tubule formation (P = 0.040) and lymph node metastasis (P = 0.016). The results support the hypothesis that TAMs influence angiogenesis in CMT suggesting TAMs may represent a therapeutic target in this disease.

COX-2 expression affects mammary tumourigenesis by promoting angiogenesis and cell proliferation, encouraging metastatic spread and tumour-associated inflammation. Samples of canine mammary tumours (n = 109) were submitted to immunohistochemistry to detect COX-2, CD31, VEGF, Ki-67, CD3 and MAC387 expression. Concurrent high expression of COX-2/CD31, COX-2/VEGF, COX-2/Ki-67, COX-2/CD3 and COX-2/MAC was associated with elevated grade of malignancy, presence of intravascular emboli and presence of lymph node metastasis. Tumours with high COX-2 (P < 0.001) and tumours with concurrent expression of high COX-2 and high CD31 (P = 0.008); high VEGF (P < 0.001); high Ki-67 (P < 0.001); high CD3+ T-lymphocytes (P = 0.002) and elevated MAC387 macrophages (P = 0.024) were associated with shorter overall survival (OS) time. Interestingly the groups with high COX-2/CD31 and high COX-2/VEGF retained their significance after multivariate analysis arising as independent predictors of OS. Present data highlight the importance of COX-2 in canine mammary tumourigenesis.

Inflammatory breast cancer (IBC) in humans is the most aggressive form of mammary gland cancer and shares clinical, pathologic, and molecular patterns of disease with canine inflammatory mammary carcinoma (CIMC). Despite the use of multimodal therapeutic approaches, including targeted therapies, the prognosis for IBC/CIMC remains poor. The aim of this review is to critically analyze IBC and CIMC in terms of biology and clinical features. While rodent cancer models have formed the basis of our understanding of cancer biology, the translation of this knowledge into improved outcomes has been limited. However, it is possible that a comparative "one health" approach to research, using a natural canine model of the disease, may help advance our knowledge on the biology of the disease. This will translate into better clinical outcomes for both species. We propose that CIMC has the potential to be a useful model for developing and testing novel therapies for IBC. Further, this strategy could significantly improve and accelerate the design and establishment of new clinical trials to identify novel and improved therapies for this devastating disease in a more predictable way.

Tumour-associated macrophages (TAMs) have already been associated in human breast cancer to a poor prognosis. As a part of a tumoural microenvironment, TAMs have an important contribution influencing neoplastic progression. Hitherto, in canine mammary tumours (CMT) the prognostic value of TAMs has not been reported. In this study, MAC387 immunohistochemical expression was evaluated in 59 CMTs (20 benign and 39 malignant). The TAM value was significantly higher in malignant than benign CMT (P = 0.011). In malignant CMT, TAMs were associated with skin ulceration (P = 0.022), histological type (P = 0.044), nuclear grade (P = 0.031) and tubular differentiation (P = 0.042). The survival analysis revealed a significant association between tumours with higher levels of TAMs and the decrease in overall survival (P = 0.030). TAMs have proven to have a prognostic value. These findings suggest the future possibility of using TAMs as a novel therapeutic target in CMT.

BackgroundCanine mammary carcinoma is the most common cancer in female dogs and is often fatal due to the development of distance metastasis. The microenvironment of a tumour often contains abundant infiltrates of macrophages called tumour-associated macrophages (TAMs). TAMs express an activated phenotype, termed M2, which sustains proliferation of cancer cells, and has been correlated with poor clinical outcomes in human cancer patients. Cancer cells themselves have been implicated in stimulating the conversion of macrophages to a TAM with an M2 phenotype. This process has yet to be fully elucidated. Here we investigate the interplay between cancer cells and macrophages in the context of canine mammary carcinoma.ResultsWe show that cancer cells inhibit lipopolysaccharide (LPS)-induced macrophage activation. Further, we show that macrophage associated proteins, colony-stimulating factor (CSF)-1 and C-C motif ligand (CCL)-2, stimulate macrophages and are responsible for the effects of cancer cells on macrophages. We suggest the existence of a feedback loop between macrophages and cancer cells; while cancer cells influence the phenotype of the TAMs through CSF-1 and CCL2, the macrophages induce canine mammary cancer cells to upregulate their own expression of the receptors for CSF-1 and CCL2 and increase the cancer cellular metabolic activity. However, these cytokines in isolation induce a phenotypic state in macrophages that is between M1 and M2 phenotypes.ConclusionsOverall, our results demonstrate the extent to which canine mammary carcinoma cells influence the macrophage phenotype and the relevance of a feedback loop between these cells, involving CSF-1 and CCL2 as important mediators.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0473-y) contains supplementary material, which is available to authorized users.

COX-2 overexpression is associated with several hallmarks of carcinogenesis such as proliferation, angiogenesis, invasion and metastasis. Fifty cases of canine mast cell tumours (MCT) were retrospectively evaluated and submitted to immunohistochemistry for COX-2, CD31, Ki-67, MAC-387 and CD3. Furthermore its relationship with clinicopathological variables and overall survival (OS) was analysed. COX-2 intensity (P = 0.016), but not COX-2 extension nor score was associated with decreased OS and higher grades of malignancy according to Patnaik (P = 0.002) and Kiupel (P < 0.001) grading systems. Cox-2 intensity was also associated with higher Ki-67 scores (P = 0.009), higher mitotic index (P = 0.022) and higher microvascularization density (P = 0.045). No association was observed for COX-2 intensity and CD3-T lymphocyte (P = 0.377) and macrophage infiltration (P = 0.261) by MAC-387 immunollabelling, suggesting an active role of COX-2 in MCT oncogenesis mainly through proliferation and angiogenesis stimulation making it a potentially clinical relevant prognosis marker and therapeutic target.

Cyclooxygenase-2 (COX-2) is known to be involved in tumour progression and has been suggested as a therapeutic target in many human and animal malignancies. A number of different pathways subjacent to cancer hallmarks are considered to be involved in COX-2-mediated tumour progression, although these are still largely undefined. Our aim is to investigate associations between COX-2 expression and angiogenesis, proliferation and the inflammatory microenvironment in canine melanocytic tumours. Understanding the involvement of COX-2 with cancer hallmarks might enable us to adapt therapeutic strategies for canine melanomas, an aggressive and often lethal malignancy with value in comparative oncology. Immunohistochemical staining of COX-2, Ki-67 (proliferation index), vascular endothelial growth factor (VEGF), factor VIII (microvessel density), CD3 (lymphocytes) and MAC387 (macrophages) was performed in 51 melanocytic tumours (31 malignant melanomas, 20 melanocytomas). Statistical associations between COX-2 and the other parameters detected were analysed. In melanocytic tumours (n=51), both COX-2 labelling extension and intensity showed a statistically significant association with angiogenesis by factor VIII, VEGF, Ki-67, CD3+ T lymphocytes and MAC387. Within malignant melanomas, COX-2 expression has shown significant associations with microvessel density (factor VIII), lymphocyte and macrophage infiltration and, considering all melanocytic tumours, COX-2 was also associated with VEGF intensity and Ki-67 cell proliferation. Our results point to a role for COX-2 in angiogenesis and in the establishment of an inflammatory microenvironment, favourable to melanoma tumour progression. Further mechanistic studies are warranted to dissect molecular pathways in which COX-2 is involved. Present evidence suggests that COX-2 inhibitors might be useful as an adjuvant treatment to hinder canine melanoma progression.