Proliferative Activity, Apoptosis and Expression of Oestrogen Receptor and Bcl-2 Oncoprotein in Canine Mammary Gland Tumours

Evidence for heterogeneity in response to treatment in mammary tumors of dogs as happens in humans

Tumors are formed by various clones developed over a long time. This gives rise to a heterogeneous nature. This heterogeneity is the hardest challenge in the treatment of cancers because it is the main reason for drug resistance. This is a well-known fact in human cancer. Therefore, we have reasoned that if the tumor heterogeneity in canine mammary gland tumors (CMGTs) could be shown by an ex vivo assay, which will be used first time in veterinary oncology practice, this could be used further in clinics. To achieve this, twenty-six patients were included in the study. Tumor tissues were obtained from animals during routine surgery. Tumor cells were isolated and seeded ex vivo. The cells were exposed to anticancer drugs that are clinically used. Seven days after the treatment, chemosensitivity has luminometrically been assayed by ATP-tumor chemosensitivity assay (ATP-TCA). It has clearly been shown that all the tumor tissues have responded to treatment differently, implying that heterogeneity exists in mammary tumors. There has also been found that there was a weak to moderate statistically significant correlation between tumor size and drug index. However, there has been no correlation between drug index and metastasis to lymph nodes. Hyperplasic areas had relatively higher PCNA values. The results of our study demonstrate the heterogeneity in responses to in vitro drugs. Clinical trials based on test results and follow-up studies with large numbers of animals are needed to prove that such chemotherapeutic activity assessment tests can be clinically useful in predicting drug responses in CMGTs.

Hormonal Homologies between Canine Mammary Cancer and Human Breast Cancer in a Series of Cases

Simple Summary

There is worldwide interest in understanding the cancerous diseases that are causing increasing deaths in humans. In recent years, interest has grown in finding suitable models of different types of cancer in animals to lead the scientific community to a better understanding of the disease, in order to win the battle against cancer. The aim of this investigation was to compare breast cancer samples and canine mammary tumors from a hormonal point of view to validate the canine species as a model to study human breast cancer. There was a close similarity between premenopausal human breast cancer and canine mammary cancer in terms of hormonal receptors. In both species, all hormones assayed were increased in tumors compared to normal mammary gland samples. This research not only further supports canine mammary cancer as a spontaneous model for the study of human breast cancer but is also important in providing a deeper understanding of the hormonal pathogenesis of breast/mammary cancer in each independent species.

Abstract

The validity of spontaneous canine mammary cancer (CMC) as a natural model for the study of human breast cancer (HBC) from a hormonal point of view has never been thoroughly investigated. In this study, we analyzed the immunohistochemical expression of aromatase (Arom) and steroid receptors [estrogen receptor α (ER α), estrogen receptor β (ER β), progesterone receptor (PR) and androgen receptor (AR)] and intratumor steroid hormone levels of 17β-estradiol (E2), estrone sulfate (SO4E1), progesterone (P4), androstenedione (A4), dehydroepiandrosterone (DHEA), and testosterone (T) in 78 samples of mammary cancer—51 human breast cancer (HBC) and 27 canine mammary cancer (CMC)—and corresponding controls. Frequency of tumors expressing Arom, ERβ, PR, and AR was similar in both species, whereas ERα+ tumors were less frequent in the canine species. There was a closer similarity between premenopausal HBC and CMC. In HBC and CMC, all hormones assayed were increased in tumors compared to control samples. Intratumor androgen levels were similar in the two species, although levels of progesterone and estrogens were higher in the HBC samples than the CMC samples. Statistical associations among Arom, receptors, and hormones analyzed suggest that the major hormonal influence in both species is estrogenic through the ER, being the α isoform predominant in the human samples. Our findings further support CMC as a spontaneous model for the study of HBC, especially premenopausal HBC, although several differences, such as the more prevalent ERα immunoexpression and higher intratumor levels of estrogens and P4 in HBC, should be taken into account in comparative hormonal studies.

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) loss in canine mammary carcinoma

Escaping apoptosis is a hallmark of cancer. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), a central molecule that regulates the extrinsic apoptotic pathway, has been widely investigated in human oncology; however, investigations focusing on the endogenous expression of TRAIL in canine tumours are lacking. Therefore, we aimed to examine the expression of endogenous TRAIL in canine mammary tumours and analysed its correlation with downstream molecules Fas-associated protein with death domain (FADD) and caspase-3, and to the apoptotic index. A total of 147 samples, classified as normal mammary gland (n = 9), mammary adenoma (n = 30), low-grade carcinoma (n = 42) and high-grade carcinoma (n = 66), were included in the immunohistochemical analyses, and 43 samples with sufficient levels of RNA were analysed via RNA in situ hybridization and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay. In immunohistochemistry, TRAIL protein expression was significantly decreased in high-grade carcinoma compared to those in normal mammary gland and adenoma, with similar downregulation of TRAIL mRNA expression. Also, FADD and caspase-3 expression positively correlated with TRAIL expression. However, the apoptotic index was paradoxically elevated in high-grade tumours. Overall, these results suggest that the loss of TRAIL accompanied by dysregulation of TRAIL-induced extrinsic apoptotic pathway molecules could affect malignant progression of canine mammary tumours.

Pathological and Immunohistochemical Microscopy of Natural Cases of Canine and Feline Neoplastic Mammary Lesions

Mammary cancer is the second most common tumor worldwide. Small animal mammary neoplasms provide an outstanding model to study cancer in humans, as tumors in both share a similar environment, histopathologic features, and biological behavior. This study aims to investigate the percentage and microscopy of breast tumors in affected dogs and cats; its relationship to breed, age, and sex; and the immunohistochemical expression of estrogen receptor (ER), progesterone receptor (PR), Ki-67, and cytokeratin 8. Twenty-four females (12 dogs and 12 cats) and one male were examined from February 2018 to February 2020. The highest percentage of mammary neoplasia from the highest to the lowest manifested as tubular carcinoma, leiomyosarcoma, fibroadenoma, and cystic papillary carcinoma. The current study reported the second micropapillary invasive carcinoma in a male cat and the third lipid-rich carcinoma in a female cat. Although tubular carcinoma was the most common mammary neoplasm in cats, leiomyosarcoma was the most common in dogs. The immunohistochemical staining revealed diffuse and intense cytoplasmic immunoreactivity for cytokeratin 8 in lipid-rich carcinomas. However, moderate expression of ER in benign tumors and slight to moderate ER expression in malignant mammary lesions were reported. On the contrary, there was a negative PR expression in benign lesion. It could be concluded that a close relationship between ER expression and nuclear antigen Ki-67 was found.

Prevalence of malignancy in masses from the mammary gland region of dogs with single or multiple masses

OBJECTIVE

To determine the prevalence of malignancy in masses from the mammary gland region of dogs with single or multiple masses.

ANIMALS

95 female dogs from which mammary gland masses had been excised.

PROCEDURES

Medical records of all female dogs from which mammary gland tissue was submitted to the Angell Animal Medical Center Pathology Department from 2009 through 2014 were reviewed. For each dog, data were obtained on breed, body weight, age, reproductive status, and number, location, and histologic classification of masses. The prevalence of malignancy was compared between dogs with single versus multiple masses and among the 5 pairs of mammary glands. Dogs with single versus multiple masses were also compared with respect to age and reproductive status.

RESULTS

Among 161 evaluated masses, 137 (85%) were classified as benign or nonneoplastic and 24 (15%) as malignant. Five of 95 (5%) dogs had masses that were not of mammary gland origin. Age, reproductive status, and quantity of masses (single vs multiple) were not significantly associated with the prevalence of malignancy. The prevalence of malignancy in masses from the fourth (caudal abdominal) mammary gland was significantly lower than that in the other 4 mammary glands combined.

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs with multiple masses in the mammary gland region were not significantly more likely than dogs with single masses to have a malignancy, suggesting that these 2 groups could be managed similarly. Further studies are needed to evaluate the clinical relevance of the lower prevalence of malignancy in masses from the fourth mammary gland.

Low-quality rice straw forage increases the permeability of mammary epithelial tight junctions in lactating dairy cows

BACKGROUND

It is known that milking frequency and plasma hormones play important roles in regulating mammary permeability. However, it is still not known whether nutritional factors can influence udder permeability.

DESIGN

This study was conducted to investigate mammary epithelial tight-junction permeability in lactating dairy cows fed different forage-based diets. Twenty mid-lactating dairy cows were allocated to ten blocks based on their parity and milk yield and then randomly assigned into rice straw-based diet and alfalfa-based diet groups. Both diets contained 15% corn silage and 55% concentrate (dry matter basis). In terms of forage sources, rice straw-based diets (RS) contained 30% rice straw, whereas alfalfa-based diets (AH) contained 23% alfalfa hay plus 7% Chinese wild rye hay.

RESULTS

The concentrations of Na⁺ , Na⁺ /K⁺ ratio, bovine serum albumin, and plasmin in the milk, the plasma lactose concentration, and the mRNA abundance of BCL2 associated agonist of cell death, phosphatase and tensin homolog, and insulin like growth factor binding protein 5 in the mammary gland were greater in RS-fed cows than in AH-fed animals. Mammary expression of proliferating cell nuclear antigen and occludin was lower in RS-fed cows compared with the AH-fed group. The expressions of growth hormone receptor, claudin-1, -3, -4, and ZO-1 were similar in the two diet groups.

CONCLUSION

The cows fed RS showed higher mammary alveolar permeability, likely due to its effect on proliferation/apoptosis rates of mammary epithelial cells. © 2018 Society of Chemical Industry.

Current biomarkers of canine mammary tumors

Mammary tumors are the second most common neoplasia in dogs. Due to the high similarity of canine mammary tumors (CMT) to human breast cancers (HBC), human biomarkers of HBC are also detectable in cases of CMT. The evaluation of biomarkers enables clinical diagnoses, treatment options and prognosis for bitches suffering from this disease. The aim of this article is to give a short summary of the biomarkers of CMT based on current literature. Very promising biomarkers are miRNAs, cancer stem cells, and circulating tumor cells, as well as mutations of the breast cancer 1 gene (BRCA1) and breast cancer 2 gene (BRCA2). Until now, the most studied and reliable biomarkers of CMT have remained antigen Ki-67 (Ki-67), endothelial growth factor receptor, human epidermal growth factor receptor 2 (HER-2), estrogen receptor, progesterone receptor and cyclooxygenase 1 (COX-2), which can be detected in both serum and tissue samples using different molecular methods. However, carcinoembryonic antigen and cancer antigen 15-3 (CA 15-3), while poorly studied, seem to be good biomarkers, especially for the early detection and prognosis of CMT. We will also mention the following: proliferative cell nuclear antigen, tumor protein p53 (p53), E-cadherin, vascular endothelial growth factor, microRNAs, cancer stem cells and circulating tumor cells, which can also be useful biomarkers. Although many studies have been conducted so far, the estimation of biomarkers in cases of CMT is still not a common practice, and more detailed research should be done.

Comparative histopathology and immunohistochemistry of human and canine mammary tumors

This study aimed at establishing aspects of comparison between canine and human mammary gland tumors. In order to achieve that, 44 specimens of canine mammary tumors and 70 specimens of human breast tumors were examined in order to state points of similarity in morphology, cells of origin, behavior and existence of tissue markers. We found that the ratio of benign to malignant forms was 4.5% to 95.5% in canine samples and 45.7% to 54.3% in human samples. In both species, malignant tumors composed of infiltrating ductal cells were in the forefront despite dissimilarity in nomenclature. Other kinds of lower rate of existence included, invasive micro-papillary carcinoma, mucinous carcinoma and invasive comedo-carcinoma which have displayed similar morphology and terminology in both species. Chondroid and squamous differentiation were found in human and canine specimens. In human samples, fibro-adenoma mounted up to 30 out of 32 benign tumors (93.8%). Her-2 and Ki-67 were detected in the specimens of both species but ER was detected in human specimens only. Our findings suggest a significant degree of resemblance between certain mammary tumor in canine and human. Such findings are in support of employing dogs in research investigation for human mammary tumors.

Immunohistochemical evaluation of bcl-2, ER-alpha, caspase -3, -8, -9, PCNA and Ki-67 expressions in canine mammary carcinomas

We investigated the expression of bcl-2, estrogen receptor alpha (ER-alpha), caspase-3, -8, -9, proliferating cell nuclear antigen (PCNA) and Ki-67 in canine mammary carcinomas. We used 65 paraffin embedded and re-diagnosed archival canine mammary tumor samples to which we applied the routine streptavidin-biotin-peroxidase technique. Seventeen cases were re-diagnosed as tubulopapillary carcinoma, 31 were re-diagnosed as complex carcinoma and 17 were re-diagnosed as carcinosarcoma. Differences of expression of bcl-2 and PCNA were statistically significant according to tumor type. Differences in expression of ER-alpha, caspase-3, -8, -9 and Ki-67 were not statistically significant. Differences of expression of bcl-2 and PCNA were statistically significant compared to ER-alpha, caspase-3, -8, -9 and Ki-67 in carcinosarcomas. We report the prognostic significance of bcl-2 and PCNA expression in canine mammary carcinosarcomas.

Hematoporphyrin monomethyl ether combined with He-Ne laser irradiation-induced apoptosis in canine breast cancer cells through the mitochondrial pathway

Hematoporphyrin monomethyl ether (HMME) combined with He-Ne laser irradiation is a novel and promising photodynamic therapy (PDT)-induced apoptosis that can be applied in vitro on canine breast cancer cells. However, the exact pathway responsible for HMME-PDT in canine breast cancer cells remains unknown. CHMm cells morphology and apoptosis were analyzed using optical microscope, terminal deoxynucleotidyl transferase dUTP nick end labeling fluorescein staining and DNA ladder assays. Apoptotic pathway was further confirmed by Real-time-polymerase chain reaction and Western blotting assays. Our results showed that HMME-PDT induced significant changes in cell morphology, such as formation of cytoplasmic vacuoles and the gradual rounding of cells coupled with decreased size and detachment. DNA fragmentation and cell death was shown to occur in a time-dependent manner. Furthermore, HMME-PDT increased the activities of caspase-9 and caspase-3, and released cytochrome c from mitochondria into the cytoplasm. HMME-PDT also significantly increased both mRNA and protein levels of Bax and decreased P53 gene expression in a time-dependent manner, while the mRNA and protein expression of Bcl-2 were repressed. These alterations suggest that HMME-PDT induced CHMm cell apoptosis via the mitochondrial apoptosis pathway and had anti-canine breast cancer effects in vitro.

Binding Specificity of Radiolabeled Cyclic Peptide 153Sm-DTPA-c(CGRRAGGSC) to MHCC97-H Human Liver Cancer Cells and its Antitumor Effects in vivo

Objective:

This objective of this study is to investigate the effects of the radiolabeled cyclic peptide 153Sm-DTPA-c(CGRRAGGSC) on MHCC97-H human liver cancer cells in vitro and in vivo.

Methods:

The protein expression levels were examined by Western blot analysis. Biological activity of 153Sm-DTPA-c(CGRRAGGSC) was assessed with the radioligand binding assay and competitive inhibition experiment. Subcellular localization of the cyclic peptide was observed by fluorescence microscopy. Animals were implanted with MHCC97-H cells and administered with 153Sm-DTPA-c(CGRRAGGSC). Hematoxylin and eosin staining, electron microscopy, and immunohistochemistry were performed to evaluate the effects of 153Sm-DTPA-c(CGRRAGGSC) on implanted tumors.

Result:

The expression levels of interleukin 11 receptor were significantly elevated, by 2-to 5-fold, in tumor cell lines, especially for MHCC97-H cells. Characterization of 153Sm-DTPA-c(CGRRAGGSC) showed that the biological activity of the cyclic peptide was not altered after labeling, and the radiolabeled cyclic peptide exhibited sufficient binding affinity to interleukin 11 receptor . The cyclic peptide of c(CGRRAGGSC) was mainly distributed in the cytoplasm and on the cell membrane of MHCC97-H cells. The in vivo experiments showed that the tumor growth was significantly inhibited by the treatment of 153Sm-DTPA-c(CGRRAGGSC). The inhibitory effect of 153Sm-DTPA-c(CGRRAGGSC) on tumor growth was further confirmed by Hematoxylin and eosin staining, electron microscopy, and immunohistochemistry. Moreover, the expression levels of interleukin 11 receptor in implanted tumors were significantly decreased in the treatment groups.

Conclusion:

153Sm-DTPA-c (CGRRAGGSC) could specifically bind to interleukin 11 receptor on MHCC97-H liver tumor cells, inhibiting the cell proliferation and inducing cellular apoptosis. These findings provide experimental evidence for the development of individual treatment of liver cancers, as well as recurrence and metastasis.

Evaluation of apoptosis-associated protein (Bcl-2, Bax, cleaved caspase-3 and p53) expression in canine mammary tumors: An immunohistochemical and prognostic study

Apoptosis is an important process involved in pathogenesis and progression of neoplasia. However, it has been not so far extensively investigated in canine mammary tumors (CMTs). Therefore the aim of our study was to determine Bcl-2, Bax, cleaved caspase-3 (CC3) and p53 expression in CMTs and evaluate their correlation with host/tumor factors, and overall survival (OS). Bcl-2 expression was often found in benign lesions and in patients with low TNM stage. Expression of Bax, CC3 and p53 was observed in malignant CMTs. The expression of apoptosis-associated proteins was not significantly associated with OS. A positive-p53 status was significantly related with poorer tumor differentiation, higher mitotic index (MI), more invasive growth, necrosis, and occurred often in CMTs from large breed dogs. In the shorter-survival group of dogs (≤18 months), a positive correlation was found between CC3 and Bcl-2 expression; CC3 and MI, ERα and p53 expression, while in the longer-survival group (>18 months) CC3 expression was negatively correlated with ERα, whereas p53 expression was positively correlated with MI. We confirmed the usefulness of such parameters as: tumor size, MI, type of growth, tumor metastasis and TNM stage in predicting OS in a univariate analysis. In multivariate analysis we identified age as an independent prognostic factor for OS. Expression of single apoptosis-associated protein should not be used as a prognostic marker. However, we showed significant correlation patterns of expression of proteins involved in apoptotic-signaling pathways in shorter- and longer survival groups. So far, there have been only a few similar reports published.

Sequence and partial functional analysis of canine Bcl-2 family proteins

Dogs present with spontaneous neoplasms biologically similar to human cancers. Apoptotic pathways are deregulated during cancer genesis and progression and are important for therapy. We have assessed the degree of conservation of a set of canine Bcl-2 family members with the human and murine orthologs. To this end, seven complete canine open reading frames were cloned in this family, four of which are novel for the dog, their sequences were analyzed, and their functional interactions were studied in yeasts. We found a high degree of overall and domain sequence homology between canine and human proteins. It was slightly higher than between murine and human proteins. Functional interactions between canine pro-apoptotic Bax and Bak and anti-apoptotic Bcl-xL, Bcl-w, and Mcl-1 were recapitulated in yeasts. Our data provide support for the notion that systems based on canine-derived proteins might faithfully reproduce Bcl-2 family member interactions known from other species and establish the yeast as a useful tool for functional studies with canine proteins.

Tarantula cubensis extract alters the degree of apoptosis and mitosis in canine mammary adenocarcinomas

In the present study, 13 clinical cases of canine mammary adenocarcinoma were evaluated in order to understand the effect of Tarantula cubensis extract (TCE) on tumor tissue. Punch biopsies were taken from the tumors before treatment with TCE. Subcutaneous injections of TCE were administered three times at weekly intervals (3 mL per dog). Between days 7 and 10 after the third injection, the tumor masses were extirpated by complete unilateral mastectomy. Pre- and post-treatment tumor tissues were immunohistochemically assessed. The expression of B-cell lymphoma 2 (Bcl-2) was found to be higher in pre-treatment compared to post-treatment tissues (p < 0.01) whereas Ki-67 expression was lower in post-treatment tissues (p < 0.01). No significant differences in fibroblast growth factor or vascular endothelial growth factor expression were observed between pre- and post-treatment tissues (p > 0.05). The apoptotic index was determined to be low before treatment and increased during treatment. These results suggest that TCE may be effective for controlling the local growth of canine mammary adenocarcinoma by regulating apoptosis.

IgE-based immunotherapy of cancer: challenges and chances

Passive immunotherapy with monoclonal antibodies is an indispensable cornerstone of clinical oncology. Notably, all FDA-approved antibodies comprise the IgG class, although numerous research articles proposed monoclonal antibodies of the IgM, IgG, IgA and IgE classes directed specifically against tumor-associated antigens. In particular, for the IgE isotype class, several recent studies could demonstrate high tumoricidic efficacy. Therefore, this review specifically highlights the latest developments toward IgE-based immunotherapy of cancer. Possible mechanisms and safety aspects of IgE-mediated tumor cell death are discussed with special focus on the attracted immune cells. An outlook is given on how especially comparative oncology could contribute to further developments. Humans and dogs have a highly comparable IgE biology, suggesting that translational AllergoOncology studies in patients with canine cancer could have predictive value for the potential of IgE-based anticancer immunotherapy in human clinical oncology.

Canine mammary tumors: a review and consensus of standard guidelines on epithelial and myoepithelial phenotype markers, HER2, and hormone receptor assessment using immunohistochemistry

Although there have been several studies on the use of immunohistochemical biomarkers of canine mammary tumors (CMTs), the results are difficult to compare. This article provides guidelines on the most useful immunohistochemical markers to standardize their use and understand how outcomes are measured, thus ensuring reproducibility of results. We have reviewed the biomarkers of canine mammary epithelial and myoepithelial cells and identified those biomarkers that are most useful and those biomarkers for invasion and lymph node micrometastatic disease. A 10% threshold for positive reaction for most of these markers is recommended. Guidelines on immunolabeling for HER2, estrogen receptors (ERs), and progesterone receptors (PRs) are provided along with the specific recommendations for interpretation of the results for each of these biomarkers in CMTs. Only 3+ HER2-positive tumors should be considered positive, as found in human breast cancer. The lack of any known response to adjuvant endocrine therapy of ER- and PR-positive CMTs prevents the use of the biological positive/negative threshold used in human breast cancer. Immunohistochemistry results of ER and PR in CMTs should be reported as the sum of the percentage of positive cells and the intensity of immunolabeling (Allred score). Incorporation of these recommendations in future studies, either prospective or retrospective, will provide a mechanism for the direct comparison of studies and will help to determine whether these biomarkers have prognostic significance. Finally, these biomarkers may ascertain the most appropriate treatment(s) for canine malignant mammary neoplasms.

Diagnosis, classification and grading of canine mammary tumours as a model to study human breast cancer: an Clinico-Cytohistopathological study with environmental factors influencing public health and medicine

BACKGROUND

The human "Elston and Ellis grading method" was utilized in dogs with mammary tumor to examine its relation to prognosis in this species, based on a 2-year follow-up period. Although cytopathology is widely used for early diagnosis of human neoplasms, it is not commonly performed in veterinary medicine. Our objectives in this study were to identify cytopathology criteria of malignancy for canine mammary tumors and the frequency of different types of mammary lesions and their relationship with histologic grade was investigated. Another aim of this study was to differentiate the simple and adenocarcinoma tumors from the complex or mixed tumor described by Elston and Ellis grading method.

METHODS

The study was performed in 15 pure or mixed-breed female dogs submitted to surgical resections of mammary tumours. The mammary tumours were excised by simple mastectomy or regional mastectomy, with or without the superficial inguinal lymph nodes. Female dogs were mainly terriers (9 dogs) or mixed (3 dogs), the 3 other animals were a German shepherd, Dachshund and Pekingese. Before surgical excision of the tumour, FNAC was performed using a 0.6 mm diameter needle attached to a 10 ml syringe held in a standard metal syringe holder. The cytological sample was smeared onto a glass slide and either air-dried for May-Grünwald-stain, or ethanol-fixed for Papanicolaou stain and masses were surgically removed, the tumours were grossly examined and tissue samples were fixed in 10%-buffered-formalin and embedded in paraffin. Sections 4 μm thick were obtained from each sample and H&E stained.

RESULTS

We obtained a correct cytohistological correlation in 14/15 cases (93.3%) when all cytopathological examinations were considered. Of the 15 cases examined, 2(13.3%) had well-differentiated (grade I), 6(40%) had moderately differentiated (grade II) and 7(46.7%) had poorly differentiated (grade III) tumours. Classification of all canine mammary gland lesions revealed 13(86.7%) malignant and 2(13.3%) benign tumors. The histological examination showed that the most common tumor types of mammary glands in bitches were: complex carcinoma, adenocarcinoma, malignant mixed tumour, benign mixed tumour, simple carcinoma- (5/15; 33.3%), (3/15; 20%), (3/15; 20%) and (2/15;13.3%), respectively. Simple carcinoma and cystic hyperplasia were less common - (1/15; 6.7%), and (1/15; 6.7%), respectively. Moreover, the most often tumors occur in inguinal mammary (60%) and abdominal (27%) glands.

CONCLUSIONS

Our results demonstrate that, because of the similarity of the cytohistopathological findings in the human and canine mammary gland tumours, it is possible to use the same cytopathological criteria applied in human pathology for the diagnosis of canine mammary gland tumours. Furthemoer, routine use of this human grading method would help the clinician to make a more accurate prognosis in the interests of post-surgical management in dogs with mammary carcinomas. Furthermore, this research will allow a more discriminating classification of mammary tumors and probably has a bearing on cytohistopathology, epidemiology, pathogenesis and prognosis. The most often tumors occur in inguinal mammary (60%) and abdominal (27%) glands. This interesting regional difference may be due to a) the duration of the growth before the diagnosis; b) the age of the dogs; and c) high prevelance of unspayed animals. Moreover, the most common type of tumor was complex carcinoma - 33.3% (5 cases).

Therapeutic efficacy of ABT-737, a Bcl-2 inhibitor, in a canine melanoma cell line

The small molecule inhibitor, ABT-737, inhibits Bcl-2 that is overexpressed in many tumor cell lines and, in combination with an anticancer drug, can strongly enhance proapoptotic activity. In the present study, we evaluated the inhibitory activity of ABT-737 on the survival of a canine melanoma cell line (MCM-N1). MCM-N1 cell viability was decreased following 24- and 48-hr culture with ABT-737, depending on ABT-737 concentration, while cell viability was unchanged in controls. ABT-737 synergized with carboplatin to promote cell death. Notably, approximately 50% of MCM-N1 cells survived following culture with 2-4 µg/ml of carboplatin; whereas, less than 20% of MCM-N1 cells survived following culture with ABT-737 (1 mM) plus carboplatin (2-10 µg/ml).

Correlation of Foxp3 positive regulatory T cells with prognostic factors in canine mammary carcinomas

Regulatory T cells (Treg) cells play a crucial role in tumor progression by suppressing anti-tumor immunity, but are not well-documented in veterinary oncology. To identify the characteristics of Treg cells in tumor microenvironments, the numbers of Treg cells were analyzed and compared with histological prognostic factors and molecular biomarkers in canine mammary carcinoma (MC) tissues (n=37). Abundant Treg cells were associated with high histological grade and lymphatic invasion. The numbers of Treg cells infiltrating intratumoral areas markedly increased in tumors with poor prognostic factors, such as high histological grade, lymphatic invasion, and necrosis. These findings suggest that Treg cells play a role in canine MC progression. Furthermore, Treg cell numbers in intratumoral compartments may provide a potential prognostic factor when assessing canine MCs, which may in turn lead to the development of new immunologic therapeutics.

Canine mammary tumours, an overview

Canine mammary tumours (CMTs) are the most common neoplasms in intact female dogs. Although the prevalence of these tumours decreases in regions where preventive ovari(ohyster)ectomy is performed, it remains an important disease entity in veterinary medicine. Moreover, treatment options are limited in comparison with human breast cancer. Nevertheless, recent human treatment protocols might have potential in bitches suffering from CMTs.

Molecular carcinogenesis of canine mammary tumors: news from an old disease

Studies focusing on the molecular basis of canine mammary tumors (CMT) have long been hampered by limited numbers of molecular tools specific to the canine species. The lack of molecular information for CMT has impeded the identification of clinically relevant tumor markers beyond histopathology and the introduction of new therapeutic concepts. Additionally, the potential use for the dog as a model for human breast cancer is debatable until questions are answered regarding cellular origin, mechanisms, and cellular pathways. During the past years, increasing numbers of canine molecular tools have been developed on the genomic, RNA, and protein levels, and an increasing number of studies have shed light on specific aspects of canine carcinogenesis, particularly of the mammary gland. This review summarizes current knowledge on the molecular carcinogenesis of CMT, including the role of specific oncogenes, tumor suppressors, regulators of apoptosis and DNA repair, proliferation indices, adhesion molecules, circulating tumor cells, and mediators of angiogenesis in CMT progression and clinical behavior. Whereas the data available are far from complete, knowledge of molecular pathways has a significant potential to complement and refine the current diagnostic and therapeutic approach to this tumor type. Furthermore, current data show that significant similarities and differences exist between canine and human mammary tumors at the molecular level. Clearly, this is only the beginning of an understanding of the molecular mechanisms of CMT and their application in clinical patient management.

Prevalence and Classification of Spontaneous Mammary Intraepithelial Lesions in Dogs Without Clinical Mammary Disease

Mammary intraepithelial lesions (IELs) are noninvasive epithelial proliferations that include ductal hyperplasia (DH), atypical DH (ADH), and ductal carcinoma in situ (DCIS). In women, IELs are associated with increased risk of invasive breast cancer and form a basis for therapeutic decisions. Similarly, in female dogs, IELs are common in tumor-bearing glands and in non-tumor-bearing glands. To determine the prevalence and types of spontaneous IELs, mammary glands from 108 female dogs without clinical mammary disease were evaluated histologically and immunohistochemically. Within this population, 56 dogs (52%) had at least one type of spontaneous IEL, including DH (49 dogs), ADH (14 dogs), low-grade DCIS (19 dogs), intermediate-grade DCIS (12 dogs), and high-grade DCIS (1 dog). Twenty-one dogs had two or more different IEL types. In 23 of 24 dogs with atypical IELs (ADH or DCIS), immunohistochemical expression was determined for estrogen receptor α (ER-α), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2/neu), and Ki-67. For all markers examined, low-grade DCIS had significantly lower scores than did adjacent nonlesional gland; PR expression was significantly decreased in low-grade DCIS compared to other atypical lesions. Sixty-one lesions were ER-α negative (12 ADH, 36 low-grade DCIS, 13 intermediate-grade DCIS), and no lesions overexpressed HER-2/neu. Based on the dog’s prevalence of spontaneous mammary IELs that precede clinical mammary disease, the remarkable histologic similarity between canine and human IELs, and the loss of ER expression in certain IELs in both species, the dog shows promise as a model for human breast preneoplasia.

Secreted frizzled related protein 2 (sFRP2) decreases susceptibility to UV-induced apoptosis in primary culture of canine mammary gland tumors by NF-kappaB activation or JNK suppression

Tumor formation can result from a decrease in cell death, as well as an increase in cell proliferation. In spite of the high incidence of mammary gland tumors (MGTs) in female dogs, the understanding of its etiology is still poor. Consistent with several proto-oncogenes (such as Wnt) for the mammary gland, sFRP2 is expressed in canine MGTs which is normally silent in the mammary gland. To elucidate the roles of SFRP2 in the tumorigenesis of MGTs, apoptosis regulation mediated by sFRP2 was investigated by overexpression of sFRP2 in MGT cells. DNA fragmentation and TUNEL assays showed a decreased susceptibility of the cells to UV-induced apoptosis in the context of sFRP2 overexpression. To analyze the pathways through which sFRP2 transduces anti-apoptosis signals, multiple-color immunofluorescence staining, immunoprecipitation, and immunoblotting were carried out. sFRP2 was found co-localized in the extracellular matrix of MGTs and the tyrosine phosphorylation of FAK was enhanced. Moreover, JNK was suppressed and NF-kB was activated in the cells expressing sFRP2 after UV-induced apoptosis analyzed by immunoblotting and electrophoretic mobility shift assay (EMSA). Taken together, these results suggest that sFRP2 exerts its anti-apoptotic function in mammary cancer cells through NF-kappaB activation or JNK suppression.