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Transforming growth factor-β (TGFβ) and FoxP3 regulatory T cells (Treg) are involved in human breast carcinogenesis. This topic is not well documented in canine mammary tumors (CMT). In this work, the tumoral TGFβ expression was assessed by immunohistochemistry in 67 malignant CMT and its correlation to previously determined FoxP3, VEGF, and CD31 markers and other clinicopathologic parameters was evaluated. The high levels of TGFβ were statistically significantly associated with skin ulceration, tumor necrosis, high histological grade of malignancy (HGM), presence of neoplastic intravascular emboli and presence of lymph node metastases. The observed levels of TGFβ were positively correlated with intratumoral FoxP3 (strong correlation), VEGF (weak correlation) and CD31 (moderate correlation). Tumors that presented a concurrent high expression of TGFβ/FoxP3, TGFβ/VEGF, and TGFβ/CD31 markers were statistically significantly associated with parameters of tumor malignancy (high HGM, presence of vascular emboli and nodal metastasis). Additionally, shorter overall survival (OS) time was statistically significantly associated with tumors with an abundant TGFβ expression and with concurrent high expression of TGFβ/FoxP3, TGFβ/VEGF, and TGFβ/CD31. The presence of lymph node metastasis increased 11 times the risk of disease-related death, arising as an independent predictor of poor prognosis in the multivariable analysis. In conclusion, TGFβ and Treg cells seem involved in tumor progression emerging as potential therapeutic targets for future immunotherapy studies.

This study aims to evaluate the efficacy and side effects of low dose cyclophosphamide chemotherapy plus meloxicam as an adjuvant treatment, compared with high dose doxorubicin or surgery alone in cats with mammary carcinoma. Medical records of 228 female cats treated for mammary carcinoma between 2008 and 2018, were reviewed in eight veterinary institutions. Only cats with complete tumour staging and radical mastectomy were included in the study. One hundred and thirty-seven cats were divided into three treatment groups: group 1 (n = 80) cats treated with surgery, group 2 (n = 34) cats that had surgery and adjuvant treatment with doxorubicin, and group 3 (n = 23) cats with surgery and adjuvant treatment with low dose metronomic cyclophosphamide and meloxicam. The study endpoints were disease free interval (DFI) and overall survival (OS). Toxicity was evaluated according to the VCOG-CTCAE criteria. The median DFI was 270, 226 and 372 days in groups 1, 2 and 3, respectively. The median OS was 338 (group 1), 421 (group 2) and 430 (group 3) days. The differences between groups were not significant (DFI P = .280 and OS P = .186). Toxicity was observed in 52.9% (n = 18) of cats in group 2 and 39.1% (n = 9) of cats in group 3, with mild to moderate intensity. Differences were not significant (P = .306). In conclusion, adjuvant chemotherapy treatment did not improve survival and the overall benefit remains unproven. Randomized prospective trials are necessary to clarify the effectiveness of adjuvant chemotherapy treatment for feline mammary carcinomas., (© 2020 John Wiley & Sons Ltd.)

Blood leukocyte counts and respective derived ratios have been described as potential prognostic markers in several tumours in veterinary oncology. This study aimed to evaluate peripheral blood leukocyte subpopulations and neutrophil-to-lymphocyte ratio (NLR) as prognostic factors for feline mammary carcinomas (FMC). Medical records from cats diagnosed with FMC between 2017 to 2019 were reviewed. Cats were included if fully staged, classified as WHO stage I to III, and submitted to mastectomy. Cats were excluded if they had evidence of other diseases. Forty-nine cats were included. The study endpoints were disease-free interval (DFI) and tumour-specific survival (TSS). The median DFI and TSS were 389 days and 528 days respectively. In the univariate analysis, higher values of total white blood cell count (WBC), neutrophil count (NEU) and NLR were identified as significant prognostic factors for both endpoints (P < .05). On the multivariate analysis, NLR remained an independent prognostic factor for TSS (P = .024). In the receiver operating characteristic curve analysis, the estimated cut-off for WBC was 8.49 × 10 9 /L (DFI and TSS); for NEU was 4.62 × 10 9 /L (DFI) and 6.65 × 10 9 /L (TSS) and for NLR was 2.46. These cut-offs were significant prognostic factors for DFI and TSS (P < .05). NLR cut-off remained an independent prognostic factor for both DFI (P = .032) and TSS (P = .043) in the multivariable analysis. Our results suggest that NLR, NEU, and WBC can be important non-invasive presurgical prognostic markers, and that NLR is an independent prognostic marker for FMC. Prospective studies are warranted to validate its clinical use., (© 2021 John Wiley & Sons Ltd.)

Background/aim: IL-35 has a prominent immunosuppressive role and its overexpression has been reported in human breast cancer. However, the impact of IL-35 in canine mammary carcinogenesis has not been addressed yet. The present study determined the clinicopathological significance of IL-35 immunoexpression and its correlation with overall survival (OS) in 72 malignant canine mammary tumor (CMT) patients., Materials and Methods: Formalin-fixed paraffin-embedded malignant CMT samples (n=72) were submitted to immunohistochemical staining to detect IL-35 expression. Survival curves were obtained by the Kaplan-Meier method and the log-rank test was used for the survival estimates. Cox proportional hazard model for multivariate analysis was also performed., Results: IL-35 overexpression was associated with: skin ulceration, tumor necrosis, mitotic index, nuclear pleomorphism, tumor differentiation, histological grade of malignancy (HGM), neoplastic intravascular emboli and lymph node metastasis. Additionally, IL-35 was also correlated with a worse overall survival in multivariate analysis, arising as an independent predictor of poor prognosis., Conclusion: IL-35 is associated with carcinogenesis and worse prognosis of CMT., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: Our aim was to investigate the crosstalk between tumor and immune cells (M2 macrophages) and its effects on cyclo-oxygenase-2 (COX2) regulation in canine mammary tumors (CMT)., Materials and Methods: Sh1b CMT cells and human BT474 mammary or HT29 colon cancer cells were co-cultured with canine peripheral blood mononuclear cells (PBMCs) or with macrophage-like differentiated THP1 monocytes (dTHP1). Intracellular COX2 expression by PBMCs, dTHP1 and cancer cells was evaluated by flow cytometry., Results: Co-culturing of Sh1b and canine PBMCs induced COX2 overexpression in CMT cells. In turn, COX2 expression by PBMCs, mostly CD68 + macrophages, was attenuated by co-culture with Sh1b (p=0.0001). In accordance, co-culture with dTHP1 prompted intracellular production of COX2 in both Sh1b CMT cells and HT29 human colon cancer cells and reduced production of COX2 in BT474 human mammary cancer cells. The intracellular COX2 expression from dTHP1 decreased when treated with conditioned medium from cultured Sh1b and HT29 cancer cells., Conclusion: Bidirectional COX2 regulation between cancer and monocytes/macrophages might shape a tolerogenic tumor microenvironment in CMT., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The activity of regulatory T cells (Tregs) is closely associated with the expression of FoxP3 transcription factor. FoxP3 regulatory T cells (FoxP3Treg) have immunosuppressive properties and can work for prevention of harmful autoimmune responses, however can also interfere with beneficial anti-tumor immunity. In human breast cancer these cells play a crucial role in tumor progression. In canine mammary tumors (CMT) this topic is not well-documented. This study included 80 malignant CMT and studied, by immunohistochemistry, the intratumoral FoxP3 expression together with microvessel density (MVD), vascular endothelial growth factor (VEGF) and several clinicopathological characteristics. Abundant FoxP3Treg cells were associated with tumor necrosis (p=0.001), high mitotic grade (p<0.001), more marked nuclear polymorphism (p=0.001), poor differentiation of tumors (p<0.001), high histological grade of malignancy (HGM) (p<0.001), presence of neoplastic intravascular emboli (p<0.001) and presence of lymph node metastasis (p<0.001). Intratumoral FoxP3 was correlated with MVD (r=0.827; p<0.001) and associated with VEGF (p=0.001). Additionally tumors with abundant FoxP3Treg cells were associated with shorter overall survival (OS) time in univariate and multivariate analysis (p<0.001 Kaplan-Meier curves and 7.97 hazard ratio, p<0.001 Cox proportional hazard model). Results suggest that Treg cells play a role in CMT progression and may contribute to increased angiogenesis and aggression in these tumors. The association of intratumoral FoxP3 expression with shorter OS in multivariate analysis suggests the usefulness of Treg cells as an independent prognostic marker., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Canine inflammatory mammary cancer (IMC) and its human counterpart, inflammatory breast cancer, are extremely aggressive types of cancer. Our aim was to characterize immunohistochemical expression of C-C chemokine receptor 2, colony stimulating factor 1 receptor and metalloproteinase-9 in canine IMC versus non-IMC and to analyze associations with clinicopathological variables., Materials and Methods: Immunohistochemical staining of CCR2, CSF1R and MMP9 was performed in a series of 25 IMC and 15 non-IMC tumors., Results: No differences in the expression of these biomarkers between IMC and non-IMC were observed. Distinct nuclear subcellular expression of CCR2 was observed in IMC (p<0.001). For IMC, higher CCR2 expression was associated with increased nuclear grade (p=0.037), and higher neoplastic MMP9 expression was associated with fewer mitoses (p=0.022), higher nuclear grade (p=0.047) and increased CSF1R expression (p=0.025)., Conclusion: Expression of CCR2, CSF1R and MMP9 in canine IMC could contribute to increased nuclear pleomorphism, but the biological mechanisms involved warrant further investigation., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Unlabelled: Fifty canine mammary gland tumours (CMGT) (18 benign and 32 malignant) were studied by immunohistochemical detection of active caspase-3 and Ki-67 antigens in order to determine their association with several clinicopathological parameters. The percentage of caspase-3 positive cells was significantly higher in benign tumours as compared to their malignant counterparts (P ≤ 0.001). In the group of malignant tumours there was no significant association between active caspase-3 and the clinicopathological variables considered. The percentage of Ki- 67 positive cells was significantly higher in malignant tumours compared to the benign ones (P ≤ 0.001). In the group of malignant tumours, Ki-67 expression showed a statistically significant association with tumour size (P = 0.025), histological type (P = 0.010), mitotic grade (P ≤ 0.001), nuclear grade (P = 0.025), differentiation grade (P = 0.004), histological grade of malignancy (P = 0.002), and presence of metastases in regional lymph nodes (P = 0.025). Furthermore, this study revealed a negative correlation between the percentages of active caspase-3 and Ki-67 (r = -0.39; P = 0.04). Thus, our results suggest a loss of balance between cell death and cell division in CMGT., Key Words: Apoptosis, caspase-3, Ki.

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 in dogs, is associated with alterations in numbers and functions of immune cells at the sites of tumor progression. These tumor infiltrating immune cells seem 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 EGF, the angiogenic 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 T-lymphocytic/macrophage infiltrates and important tissue biomarkers in both human and dog mammary carcinogenesis., Competing Interests: The authors declare that they have no conflict of interests concerning the contents of this article.

Background/aim: The ability of tumors to evade the immune system is one of cancer hallmarks. In breast cancer, it has been demonstrated that the cyclooxygenase-2(+)/ epidermal growth factor receptor(+) (COX-2(+)/EGFR(+)) status might influence tumor microenvironment allowing escape of cancer cells to the immune system. This topic is unknown in canine mammary tumors (CMT). Therefore, the potential relationship between CD3(+) T-lymphocytes and concurrent COX-2/EGFR expression was investigated., Materials and Methods: Formalin-fixed paraffin-embedded malignant CMT samples (n=63) were submitted to immunohistochemical staining to detect CD3, COX-2 and EGFR., Results: Tumoral CD3(+) T-lymphocytes were significantly associated with tubular differentiation grade (p=0.006), tumor necrosis (p=0.025), histological grade of malignancy (p=0.027) and presence of lymph node metastasis (p=0.009). A correlation between COX-2 and EGFR was observed (r=0.741, p<0.0001). The COX-2(+)/EGFR(+) group was associated with tumor size (p=0.002), mitotic index (p=0.019), histological grade of malignancy (p=0.035) and presence of lymph node metastasis (p=0.041). CD3(+) T-lymphocytes and COX-2/EGFR groups were significantly associated (p=0.025) and positively correlated (r=0.399; p=0.003)., Conclusion: The present results suggest that the COX-2(+)/EGFR(+) status may be part of a strategy adopted by tumor cells to evade the cytotoxic tumor-specific immune responses., (Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

In this study 80 malignant CMT were submitted to immunohistochemical detection of CD3, c-kit, VEGF, and CD31, together with clinicopathological parameters of tumor aggressiveness. CD3+ T-cells and c-kit overexpression revealed a positive correlation with VEGF (r = 0.503, P < 0.0001; r = 0.284, P = 0.023 for CD3 and c-kit, resp.) and CD31 (r = 0.654, P < 0.0001; r = 0.365, P = 0.003 for CD3 and c-kit, resp.). A significant association (P = 0.039) and a positive correlation (r = 0.263, P = 0.039) between CD3 and c-kit were also observed. High CD3/VEGF, c-kit/VEGF, and CD3/c-kit tumors were associated with elevated grade of malignancy (P < 0.0001 for all groups), presence of intravascular emboli (P < 0.0001 for CD3/VEGF and CD3/c-kit; P = 0.002 for c-kit/VEGF), and presence of lymph node metastasis (P < 0.0001 for all groups). Tumors with high CD3/VEGF (P = 0.006), c-kit/VEGF (P < 0.0001), and CD3/c-kit (P = 0.002) were associated with poor prognosis. Interestingly high c-kit/VEGF tumors retained their significance by multivariate analysis arising as independent prognostic factor.

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.

The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor which has been shown to have an important role in human breast cancer. Its role appears to be associated with increased angiogenesis and metastasis. In order to clarify its role in canine mammary tumours (CMT), 61 malignant neoplasms were studied by using immunohistochemistry, comparing expression of EGFR, microvessel density (MVD) by CD31 immunolabelling and characteristics of tumour aggressiveness. High EGFR immunoexpression was statistically significantly associated with tumour size, tumour necrosis, mitotic grade, histological grade of malignancy and clinical stage. High CD31 immunoreactivity was statistically significantly associated with tubule formation, histological grade of malignancy and clinical stage. A positive correlation between EGFR and CD31 immunoexpression (r = 0.843; P < 0.001) was also observed. Results suggest that an over-expression of EGFR may contribute to increased angiogenesis and aggression in malignant CMT, presenting the possibility of using EGFR inhibitors in the context of metastatic disease treatment., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

We describe the case of a 14-year-old Domestic Short Hair male cat that presented with a single mammary tumour one centimetre in diameter, classified as invasive micropapillary carcinoma. Histology and immunohistochemistry revealed a high mitotic index, a KI-67 index of 10%, a lack of reactivity to myoepithelial markers, and a dense infiltration with T and B lymphocytes at the periphery of the tumour. Micrometastases were detected in the regional lymph node at the time of surgery. Overall survival time was 10 months with a disease-free interval of 7.5 months. Distant metastases in the sublumbar lymph nodes confirmed the aggressiveness of this tumour, which has recently been subtyped in female cats. This is the first case reported in male cats with a complete follow-up, highlighting the importance of prompt and aggressive treatment in the presence of mammary tumours in male cats.

This study was designed to investigate the possible roles of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in canine mammary cancer angiogenesis. Immunohistochemistry was performed on 70 tumours (28 benign and 42 malignant) in order to detect COX-2 and VEGF expression. Microvessel density (MVD) was determined by CD31 immunolabelling to assess tumour angiogenesis. There was a significantly higher expression of COX-2 (P<0.001), VEGF (P<0.001) and MVD (P<0.001) in malignant compared to benign tumours. In the malignant group, the MVD of COX-2 positive tumours was significantly higher than that of COX-2 negative tumours (P=0.026). A similar association was observed for VEGF (P<0.001) positive tumours. The results from this study suggested that over-expression of COX-2 and VEGF may contribute to increased angiogenesis and aggression in malignant tumours., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Clinical and molecular similarities between canine mammary tumours and human breast cancer have been described in recent decades. Clinically, the similarities are very strong: spontaneous tumours, hormonal aetiology, age of onset and an identical course of the disease. The clinical characteristics that have an impact on the clinical outcome are also identical: tumour size, lymph node invasiveness and clinical stage. Nowadays, as far as human medicine is concerned, the goal is to identify prognostic factors, mainly at the molecular level, such as those involved in metastasis, which could be used as therapeutic targets to support a better outcome. Moreover, in this area, canine mammary tumours seem to mimic human breast cancer, as a range of similarities are found at the molecular level concerning the overexpression of steroid receptors, proliferation markers, epidermal growth factor, p53 supressor gene mutations, metalloproteinases, cyclooxygenases, among many others. Clinical and molecular data that support canine mammary tumours as a model to study human breast cancer are analysed in this review. Additionally, it is shown that some recent molecular targets in canine mammary tumours may be seen as indicators for similar research to be performed in the corresponding human disease.

Immunohistochemical detection of Cyclooxygenase (Cox)-1 and -2 enzymes in canine mammary tumours (CMT) has recently been described. However, the prognostic value of their expression needs to be established. The aim of this study was to investigate Cox (-1 and -2) prognostic value in malignant CMT by evaluating its correlation with clinicopathological parameters (tumour size, histological type, necrosis, lymph node metastasis) and with Disease Free Survival (DFS) and Overall Survival (OS). Twenty seven female dogs with malignant tumours were included. Cox-2 expression was associated with lymph node metastasis at surgery time, development of distant metastasis during follow-up (p=0.038), DFS (p=0.03) and OS (p=0.04). Multivariate survival analysis showed that Cox-2 did not retain its significance as an independent prognostic factor. For Cox-1 expression, no statistically significant association was observed. Present study suggests the usefulness of testing Cox-2 specific inhibitors as part of an adjuvant therapy in female dogs with malignant mammary neoplasias., (Copyright 2009 Elsevier Ltd. All rights reserved.)