M1 and M2 tumour-associated macrophages subsets in canine malignant mammary tumours: An immunohistochemical study

Among the innate and adaptative immune cells recruited to the tumour site, tumour associated macrophages (TAMs) are particularly abundant and by simplified classification can be classified into (M1) and (M2) TAMs. In the present study, we quantified by immunohistochemistry ionized calcium binding adaptor molecule 1 (Iba1)-positive total and CD204-positive M2-polarized TAMs in 60 canine malignant mammary tumours (CMMTs) to analyze the relationship between M1 or M2 response and the histopathologic features of examined CMMTs, the dogs' body condition score (BCS) and the progression of the neoplastic disease. The mean number of total and CD204+ TAMS were significantly higher in solid and in grade III than in grades I and II carcinomas. Moreover, the mean number of CD204-positive TAMs was significantly higher in CMMTs with lymphatic invasion and necrosis rather than CMMTs without. The presence of higher number of CD204-positive M2-polarized TAMs was associated with a worst outcome of the neoplastic disease: bitches bearing CMMTs with a prevalent M2-polarized TAM response had a median cancer-specific survival time of 449 days, while in animals with a M1-polarized TAM response the median cancer-specific survival time was 1209 days. The results of our study confirm that in CMMTs the presence of a M2-polarized TAMs response might affect the tumour development and behaviour. Finally, it strongly suggests the potential of CD204 expression as a prognostic factor.

Chemokine gene expression influences metastasis and survival time of female dogs with mammary carcinoma

Chemokines are signaling proteins secreted by immune cells which regulate leukocyte trafficking. The aberrant expression of chemokines and their receptors by neoplastic cells influences the behaviour of many human cancers. This study evaluated gene-expression of the chemokines: CCL5, CXCL10, CXCL12 and the chemokine receptors: CXCR3, CXCR4, CXCR7, CCR4, CCR9 in 41 histologically-malignant, outcome-known, canine mammary tumours. These chemokines and chemokine receptors were selected as all were previously shown to influence the behaviour of human breast cancers. The expression of chemokines CCL5 and CXCL12 were significantly higher in tumours which subsequently metastasised than tumours that did not metastasise (p < 0.05). Increased expression of these chemokines was also correlated with shorter survival times of the dogs (CCL5: r_s = -0.40, p = 0.02, CXCL12: r_s = -0.40, p = 0.03) while CCL5 was independently prognostic of survival times (p = 0.026). A significantly higher proportion of tumours that subsequently metastasised expressed CXCR3 (p = 0.037), CXCR4 (p = 0.026), CXCR7 (p = 0.025) and CCR9 (p = 0.039) receptors while the survival times of the dogs with tumours that expressed CXCR4 (p = 0.045) and CCR9 (p = 0.039) receptors were significantly shorter than dogs with tumours that did not express these receptors. Chemokine and chemokine receptor gene-expression has not been previously correlated with disease outcome of canine mammary tumours. These findings indicate that altered expression of chemokines and their receptors influences the behaviour of canine mammary tumours suggesting a potential role of them as prognostic markers or therapeutic targets.

Malignant canine mammary tumours: Preliminary genomic insights using oligonucleotide array comparative genomic hybridisation analysis

Neoplastic mammary disease in female dogs represents a major health concern for dog owners and veterinarians, but the genomic basis of the disease is poorly understood. In this study, we performed high resolution oligonucleotide array comparative genomic hybridisation (oaCGH) to assess genome wide DNA copy number changes in 10 malignant canine mammary tumours from seven female dogs, including multiple tumours collected at one time from each of three female dogs. In all but two tumours, genomic imbalances were detected, with losses being more common than gains. Canine chromosomes 9, 22, 26, 27, 34 and X were most frequently affected. Dissimilar oaCGH ratio profiles were observed in multiple tumours from the same dogs, providing preliminary evidence for probable independent pathogenesis. Analysis of adjacent samples of one tumour revealed regional differences in the number of genomic imbalances, suggesting heterogeneity within tumours.

Significance of caveolin-1 and matrix metalloproteinase 14 gene expression in canine mammary tumours

Canine mammary tumours (CMTs) are the most common neoplasms affecting female dogs. There is an urgent need for molecular biomarkers that can detect early stages of the disease in order to improve accuracy of CMT diagnosis. The aim of this study was to examine whether caveolin-1 (Cav-1) and matrix metalloproteinase 14 (MMP14) are associated with CMT histological malignancy and invasion. Sixty-five benign and malignant CMT samples and six normal canine mammary glands were analysed using quantitative reverse transcription-polymerase chain reaction. Cav-1 and MMP14 genes were highly expressed in CMT tissues compared to normal tissues. Cav-1 especially was overexpressed in malignant and invasive CMT tissues. When a CMT cell line was cultured on fluorescent gelatin-coated coverslips, localisation of Cav-1 was observed at invadopodia-mediated degradation sites of the gelatin matrix. These findings suggest that Cav-1 may be involved in CMT invasion and that the markers may be useful for estimating CMT malignancy.

Heat shock protein 70 and nitric oxide concentrations in non-tumorous and neoplastic canine mammary tissues: preliminary results - Short communication

The concentrations of heat shock protein 70 (Hsp70) and nitric oxide ions (NO), measured as nitrite, were determined in canine mammary tumours and nontumorous mammary gland tissues. The concentrations of Hsp70 and NO were significantly higher in both benign and malignant tumours than in non-tumorous mammary tissues. Hsp70 concentration decreased with the increase in the grade of histological malignancy. A strong positive correlation was found between the concentrations of Hsp70 and NO in the benign tumours as well as in grade I and grade II malignant tumours. The results indicate that the process of neoplastic transformation in the canine mammary gland is related to a significant increase in Hsp70 and NO concentration in tumour tissues, and an interdependence between Hsp70 and nitrite ion production can be observed.

EGFR and microvessel density in canine malignant mammary tumours

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.