Steroids and receptors in canine mammary cancer

Androgen Receptors in Human Breast Cancer and Female Canine Mammary Tumors

This review explores the potential role of androgens in human breast cancer and female canine mammary tumors. Human breast cancer is one of the most common cancers affecting women globally, while female canine mammary tumors provide a natural model for the study of human breast cancer due to their similar histopathologies and molecular features. Androgen receptors, typically linked to male sex hormones, are present in up to 90% of human breast tumors. These receptors interact with estrogen-receptor signaling, suggesting their involvement in a complex mechanism in cancer progression. Androgen receptors have become key players in breast cancer biology, offering new targets for therapeutic strategies. The presence of these receptors in both human and canine tumors raises important questions about their role in the development of these malignancies. While the exact mechanisms remain to be fully elucidated, research suggests that targeting androgen-receptor signaling could be a novel therapeutic approach for both humans and canines. Further studies are necessary to fully understand the implications of androgen-receptor expression and to develop more effective targeted therapies for these cancers.

Mammary carcinoma: Comparative oncology between small animals and humans-New therapeutic tools

The poor outcomes associated with mammary carcinomas (MCs) in dogs and cats in terms of locoregional recurrence, distant metastasis and survival, highlight the need for better management of mammary cancers in small animals. By contrast, the outcomes of women with breast cancer (BC) have dramatically improved during the last 10 years, notably thanks to new therapeutic strategies. The aim of this article was to imagine what could be the future of therapy for dogs and cats with MCs if it became inspired from current practices in human BC. This article focuses on the importance of taking into account cancer stage and cancer subtypes in therapeutic plans, on locoregional treatments (surgery, radiation therapy), new developments in endocrine therapy, chemotherapy, PARP inhibitors and immunotherapy. Ideally, multimodal treatment regimens would be chosen according to cancer stage and cancer subtypes, and according to predictive factors that are still to be defined.

The inhibition of steroid hormones determines the fate of IPC-366 tumor cells, highlighting the crucial role of androgen production in tumor processes

Inflammatory mammary cancer (IMC) is a disease that affects female dogs. It is characterized by poor treatment options and no efficient targets. However, anti-androgenic and anti-estrogenic therapies could be effective because IMC has a great endocrine influence, affecting tumor progression. IPC-366 is a triple negative IMC cell line that has been postulated as a useful model to study this disease. Therefore, the aim of this study was to inhibit steroid hormones production at different points of the steroid pathway in order to determine its effect in cell viability and migration in vitro and tumor growth in vivo. For this purpose, Dutasteride (anti-5αReductase), Anastrozole (anti-aromatase) and ASP9521 (anti-17βHSD) and their combinations have been used. Results revealed that this cell line is positive to estrogen receptor β (ERβ) and androgen receptor (AR) and endocrine therapies reduce cell viability. Our results enforced the hypothesis that estrogens promote cell viability and migration in vitro due to the function of E1SO4 as an estrogen reservoir for E2 production that promotes the IMC cells proliferation. Also, an increase in androgen secretion was associated with a reduction in cell viability. Finally, in vivo assays showed large tumor reduction. Hormone assays determined that high estrogen levels and the reduction of androgen levels promote tumor growth in Balb/SCID IMC mice. In conclusion, estrogen levels reduction may be associated with a good prognosis. Also, activation of AR by increasing androgen production could result in effective therapy for IMC because their anti-proliferative effect.

Epigenetics in Canine Mammary Tumors: Upregulation of miR-18a and miR-18b Oncogenes Is Associated with Decreased ERS1 Target mRNA Expression and ERα Immunoexpression in Highly Proliferating Carcinomas

The expression of miRNAs is one of the main epigenetic mechanisms responsible for the regulation of gene expression in mammals, and in cancer, miRNAs participate by regulating the expression of protein-coding cancer-associated genes. In canine mammary tumors (CMTs), the ESR1 gene encodes for ERα, and represents a major target gene for miR-18a and miR-18b, previously found to be overexpressed in mammary carcinomas. A loss in ERα expression in CMTs is commonly associated with poor prognosis, and it is noteworthy that the downregulation of the ESR1 would appear to be more epigenetic than genetic in nature. In this study, the expression of ESR1 mRNA in formalin-fixed, paraffin-embedded (FFPE) canine mammary tumors (CMTs) was evaluated and compared with the expression levels of miR18a and miR18b, both assessed via RT-qPCR. Furthermore, the possible correlation between the miRNA expression data and the immunohistochemical prognostic factors (ERα immunoexpression; Ki67 proliferative index) was explored. A total of twenty-six FFPE mammary samples were used, including 22 CMTs (7 benign; 15 malignant) and four control samples (three normal mammary glands and one case of lobular hyperplasia). The obtained results demonstrate that miR-18a and miR-18b are upregulated in malignant CMTs, negatively correlating with the expression of target ESR1 mRNA. Of note, the upregulation of miRNAs strictly reflects the progressive loss of ERα immunoexpression and increased tumor cell proliferation as measured using the Ki67 index. The results suggest a central role of miR-18a and miR-18b in the pathophysiology of canine mammary tumors as potential epigenetic mechanisms involved in ERα downregulation. Moreover, as miRNA expression reflects ERα protein status and a high proliferative index, miR-18a and miR-18b may represent promising biomarkers with prognostic value. More detailed investigations on a larger number of cases are needed to better understand the influence of these miRNAs in canine mammary tumors.

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.

Factors related to the suppression of the antitumour immune response in female dogs with inflammatory mammary carcinoma

Inflammatory mammary carcinoma (IMC), a neoplasia affecting women and female dogs, is considered an aggressive cancer with high metastatic potential and a low survival rate. Studies focused on the tumour microenvironment indicate that the aggressive behaviour of this tumour is primarily correlated with immunological factors as well as inflammation. The objective of this study was to analyse the possible strategies used by the tumour cells to suppress the immune response in female dogs with IMC. Forty-six female dogs were divided into three groups: control (C, n = 10), IMC (n = 14) and mammary carcinoma (MC, n = 22). Clinical-pathological evaluations, survival at follow-up, immunophenotyping of leukocytes in peripheral blood and tumours, and immunohistochemical evaluation of CD4⁺, granzyme B, perforin and FAS-L were performed. Clinical and pathological results showed a higher frequency of the primary form of neoplasia, solid arrays of tumor cells and a lower survival rate in the IMC group (30 days). Morphometric analysis of inflammatory infiltrate revealed more lymphocytes and macrophages in the IMC group. Immunophenotyping analysis of peripheral blood revealed a higher frequency of CD8⁺ T-cells (p = 0.0017), a lower frequency of CD4⁺ T-cells (p <0.0001), and significantly higher mean MHCI and MHCII CD14⁺ fluorescence intensity in the IMC group (p = 0.038 and p = 0.0117, respectively). The immunohistochemical evaluation of tumour sections showed fewer FAS-L-positive inflammatory cells in the IMC group. These results suggest the important contribution of CD8⁺ T-cells, macrophages and FAS-L in the aggressiveness of IMC.

Blocking Estrogen Synthesis Leads to Different Hormonal Responses in Canine and Human Triple Negative Inflammatory Breast Cancer

Blocking estrogen synthesis by inhibitors of estrogen synthesis is a widely used therapy against estrogen receptor-positive tumors. However, these therapies are less effective in negative expression tumors. Therefore, this study determined the effectiveness of anti-aromatase and anti-sulfatase therapies in canine and human inflammatory breast cancer. Cell cultures and xenografts from IPC-366 and SUM149 were treated with different doses of letrozole (anti-aromatase) and STX-64 (anti-sulfatase), in order to observe their effectiveness in terms of cell proliferation, tumor progression, and the appearance of metastases and hormonal profiles. The results revealed that both treatments are effective in vitro since they reduce cell proliferation and decrease the secreted estrogen levels. In xenograft mice, while treatment with letrozole reduces tumor progression by 30-40%, STX-64 increases tumor progression by 20%. The hormonal results obtained determined that STX-64 produced an increase in circulating and intratumoral levels of estradiol, which led to an increase in tumor progression. However, letrozole was able to block estrogen synthesis by decreasing the levels of circulating and intratumoral estrogen and thus slowing down tumor progression. In conclusion, letrozole can be an effective treatment for canine and human inflammatory breast cancer. The knowledge of the hormonal profile of breast tumors reflects useful information on the effectiveness of different endocrine treatments.

Clinical outcome of dogs diagnosed with canine inflammatory mammary cancer treated with metronomic cyclophosphamide, a cyclooxygenase-2 inhibitor and toceranib phosphate

Canine inflammatory mammary cancer (IMC) is highly malignant, invasive and a therapeutic challenge, because effective medical treatment is still unavailable. This retrospective study compares the efficacy of an oral cyclooxygenase-2 (COX-2) inhibitor combined with toceranib phosphate and oral cyclophosphamide (multi-drug therapy [MT]) with COX-2 inhibitor therapy alone (single-drug therapy [ST]) in dogs diagnosed with secondary IMC. Clinical response, adverse events, overall survival time (OST), disease-free survival (DFS) and time to progression (TTP) were evaluated. Sixteen patients were included, eight received MT and eight receiving ST. Median OST was significantly higher in patients receiving MT (96.0 vs. 37.5 days; p = .046) and in patients with post-surgical rather than non-surgical IMC (86.5 vs. 41.5 days; p = .038). Additionally, median TTP was significantly higher in patients treated with MT (p = .010). In patients with non-surgical IMC, the clinical benefit (CB) was reached in 100% (n = 3) of patients receiving MT and in 33% (n = 1) of those receiving ST; the response duration was significantly longer in MT cases (p = .026). The absence of disease progression at day 30 of treatment was significantly associated with longer OST, DFS and TTP (p = .018, p = .002 and p < .001, respectively). Adverse events occurred more frequently in patients treated with MT compared with ST (p = .026). The MT protocol produced primarily mild to moderate toxicities, which were resolved with supportive care; therefore, the combination of drugs was adequately tolerated by most of the patients. The combination of toceranib, a COX-2 inhibitor and oral cyclophosphamide may be a protocol with potential therapeutic efficacy for dogs with IMC.

Hormonal Carcinogenesis in Canine Mammary Cancer: Molecular Mechanisms of Estradiol Involved in Malignant Progression

Mammary cancer is a frequent neoplasia in female dogs, in which most important risk factors are hormonal. Sexual hormones as estradiol play an important role in mammary carcinogenesis, being able to induce carcinogenic initiation, promotion and progression. However, the molecular mechanisms involved are incompletely understood. Estradiol is synthesized mainly in the ovaries, nevertheless, high concentrations of estradiol and some of its hormonal precursors have also been described in malignant mammary tumor tissue. The mechanisms of action of estradiol include the classic genomic effects that modulate gene transcription, and non-genomic effects, which trigger quick effects after estradiol binds to its specific receptors. These responses modulate various intracellular signaling pathways, triggering post-translational modification of several proteins. This review will discuss the well-known underlying mechanisms associated with the action of estradiol in the malignant progression of canine mammary tumors.

From Conventional to Precision Therapy in Canine Mammary Cancer: A Comprehensive Review

Canine mammary tumors (CMTs) are the most common neoplasm in intact female dogs. Canine mammary cancer (CMC) represents 50% of CMTs, and besides surgery, which is the elective treatment, additional targeted and non-targeted therapies could offer benefits in terms of survival to these patients. Also, CMC is considered a good spontaneous intermediate animal model for the research of human breast cancer (HBC), and therefore, the study of new treatments for CMC is a promising field in comparative oncology. Dogs with CMC have a comparable disease, an intact immune system, and a much shorter life span, which allows the achievement of results in a relatively short time. Besides conventional chemotherapy, innovative therapies have a large niche of opportunities. In this article, a comprehensive review of the current research in adjuvant therapies for CMC is conducted to gather available information and evaluate the perspectives. Firstly, updates are provided on the clinical-pathological approach and the use of conventional therapies, to delve later into precision therapies against therapeutic targets such as hormone receptors, tyrosine kinase receptors, p53 tumor suppressor gene, cyclooxygenases, the signaling pathways involved in epithelial-mesenchymal transition, and immunotherapy in different approaches. A comparison of the different investigations on targeted therapies in HBC is also carried out. In the last years, the increasing number of basic research studies of new promising therapeutic agents on CMC cell lines and CMC mouse xenografts is outstanding. As the main conclusion of this review, the lack of effort to bring the in vitro studies into the field of applied clinical research emerges. There is a great need for well-planned large prospective randomized clinical trials in dogs with CMC to obtain valid results for both species, humans and dogs, on the use of new therapies. Following the One Health concept, human and veterinary oncology will have to join forces to take advantage of both the economic and technological resources that are invested in HBC research, together with the innumerable advantages of dogs with CMC as a spontaneous animal model.

Do Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEAS) Play a Role in the Stress Response in Domestic Animals?

In animal husbandry, stress is often associated with poor health and welfare. Stress occurs when a physiological control system detects a state of real or presumptive threat to the animal's homeostasis or a failure to control a fitness-critical variable. The definition of stress has mostly relied on glucocorticoids measurement, even though glucocorticoids represent one stress-response system, the hypothalamus-pituitary-adrenocortical axis, which is not precise enough as it is also related to metabolic regulation and activated in non-stressful situations (pleasure, excitement, and arousal). The mammal adrenal can synthesize the androgenic steroid dehydroepiandrosterone (DHEA) and its sulfate metabolite (DHEAS), which have been associated to the stress response in several studies performed mostly in humans and laboratory animals. Although the functions of these steroids are not fully understood, available data suggest their antagonistic effects on glucocorticoids and, in humans, their secretion is affected by stress. This review explores the scientific literature on DHEA and DHEAS release in domestic animals in response to stressors of different nature (inflammatory, physical, or social) and duration, and the extra-adrenal contribution to circulating DHEA. Then, the potential use of DHEA in conjunction with cortisol to improve the definition of the stress phenotype in farmed animals is discussed. Although the focus of this review is on farmed animals, examples from other species are reported when available.

Immunohistochemical study of IGF-I and IGF-II expression in canine mammary tumours: Prognostic and diagnostic role

Mammary tumours are among the most common tumours in dogs and are of interest due to their similarities to human breast tumours. Insulin-like growth factors (IGFs) are considered important in cell growth and development. The aim of this study was to investigate the immunohistochemical expression of IGF-I and IGF-II in benign and malignant canine mammary tumours. In this study, 10 benign and 10 malignant mammary tumours from the archives of the Department of Pathology were used, and five normal breast tissues were used as controls. It was observed that the expression of IGF-I and IGF-II was low to absent in benign tumours and increased in malignant tumours. The expression of IGF-II was higher than that of IGF-I. This study showed that IGF-I and IGF-II can be used as criteria for malignancy in canine mammary tumours. The results also indicate that IGF-I and IGF-II may be used as early diagnostic markers, and their inhibition may be used for the treatment of canine and human mammary tumours in the future.

The estrogen effect; clinical and histopathological evidence of dichotomous influences in dogs with spontaneous mammary carcinomas

The purpose of this study was to investigate the associations and explore the relationships between hormonal factors (serum estrogen, estrogen receptors and ovariohysterectomy) and other clinical/histological prognostic factors and their impact on outcome in dogs with mammary carcinomas. Data from two separate prospective studies on dogs with spontaneous mammary carcinomas were used for this research. All dogs underwent standardized diagnostic testing, staging, surgery and follow-up examinations. Serum estrogen was analyzed by competitive enzyme immunoassay or radioimmunoassay, and tumor estrogen receptor (ER) expression was analyzed by immunohistochemistry. A total of 159 dogs were included; 130 were spayed and 29 remained. High serum estrogen was associated with an overall longer time to metastasis (p = 0.021). When stratifying based on spay group, the effect was only significant in spayed dogs, (p = 0.019). Positive tumor ER expression was also associated with a longer time to metastasis (p = 0.025), but similar to above, only in dogs that were spayed (p = 0.049). Further subgroup analysis revealed that high serum estrogen was significantly associated with improved survival in dogs with ER positive tumors, but only in spayed dogs (p = 0.0052). Interestingly, the effect of spaying was the opposite in dogs with ER negative tumors; here, intact dogs with high serum estrogen but ER negative tumors had a significantly longer time to metastasis (p = 0.036). Low serum estrogen was associated with increased risk for the development of non-mammary tumors in the post-operative period (p = 0.012). These results highlight the dual effect of estrogen in cancer: Estrogen acts as a pro-carcinogen in ER positive mammary tumors, but a may have a protective effect in ER negative tumors, potentially via non-receptor mechanisms. The latter is supported by the decreased risk for non-mammary tumors in dogs with high serum estrogen, and explains the increased incidence of certain non-mammary tumors in in dogs spayed at an early age.

Estrogen receptors genotypes and canine mammary neoplasia

BACKGROUND

Estrogens are essential for the development and proper function of several hormone-dependent organs. There are, however, several lines of evidence associating estrogens with mammary carcinogenesis. A marked individual genetic variability concerning estrogens biosynthesis, metabolism and mechanism of action was recognized and associated with human breast cancer susceptibility, clinical features and progression. Although some genetic variations in canine ESR1 gene were reported, their influence in clinicopathological features and progression of canine mammary tumors has not been fully evaluated. This study aims to assess the influence of SNPs in ESR1 gene (rs397512133, rs397510462, rs851327560, rs397510612, rs852887655, rs852684753 and rs852398698) in canine mammary tumors characteristics and progression. A group of 155 non-neutered bitches with mammary tumors was included in the study. Follow-up information was assessed 24 months after surgery.

RESULTS

Genetic profiles associated with a later onset of mammary tumors and less aggressive clinicopathological features, namely smaller tumor size (≤ 3 cm) with extensive tubular differentiation and low canine-adapted prognostic index (vet-NPI), were identified in this study.

CONCLUSIONS

Our data suggest that the ESR1 genetic profile may help on the decision regarding the selection of individual tailored preventive measures against canine mammary tumors development, such as early neutering.

Vasculogenic mimicry-associated ultrastructural findings in human and canine inflammatory breast cancer cell lines

Background

Human inflammatory breast cancer (IBC) and canine inflammatory mammary cancer (IMC) are the most lethal mammary cancers. An exacerbated angiogenesis and the existence of vasculogenic mimicry (VM) are hallmarks of these tumors. The information regarding VM and ultrastructural characteristics of mammary cell lines is scant.

Methods

In this study, IBC cell line SUM149 and IMC cell line IPC-366 in adherent (2D) and non-adherent (3D) (mammospheres, cancer stem cells) conditions were analyzed by transmission and scanning electron microscopy (TEM and SEM, respectively).

Results

The TEM revealed round to oval shape cells with microvilli on the surface, high numbers of peroxisomes in close apposition to lipid droplets and some extracellular derived vesicles. The TEM and the SEM mammospheres revealed group of cells clumping together with a central lumen (resembling a mammary acini). The cells joint are tight junctions and zonula adherens. By SEM two cell morphologies were observed: spherical and flattened cells. There was evidence endothelial-like cells (ELCs), which is characteristic for this disease, showing several or unique cytoplasmic empty space. ELCs were more frequent in 3D than in 2D culture conditions and contained Weibel-Palade cytoplasmic bodies, which are exclusive structures of endothelial cells.

Conclusions

Both cell lines, IPC-366 and SUM-149, shared ultrastructural characteristics, further supporting canine IMC as a model for the human disease. To the best of our knowledge, this is the first study that demonstrate the morphological differentiation of cultured cancer stem cells from cancer epithelial cell lines into endothelial-like cells, confirming the vasculogenic mimicry phenomenon from an ultrastructural point of view.

Classification, bacteriological findings, and analysis of sex hormone receptors and cytokine expression in mammary lesions of abattoir sows

Mammary lesions in sows can prevent suckling piglets from consuming colostrum that provides fundamental nutrients and protective immunity. Although mammary gross lesions are frequently found in sows at farms or slaughterhouses, with the exception of mastitis, they have received little research attention. In this study, we investigated mammary lesions observed in South Korean sows between 2015 and 2016. Mammary tissue samples of 82 sows showing gross lesions during meat inspection were histologically classified and immunohistochemical analysis was conducted to assess the expression of estrogen receptor (ER)-α, ER-β, and progesterone receptor (PR) for mammary hyperplastic lesions as well as that of cluster of differentiation (CD) 3, CD79a, interleukin (IL)-1α, IL-1β, IL-6, and IL-8 for mastitis. Furthermore, 20 swab samples were cultured, and the isolated bacteria were identified using polymerase chain reactions for 16S ribosomal RNA genes. The lesions were classified as hyperplasia, mastitis, or hyperplasia with mastitis. Immunohistochemistry results revealed that there was neither expression of ER-α nor of ER-β, but all examined hyperplastic samples expressed PR. In addition, there was a significant correlation between CD3 and IL-1β expressions, as well as between IL-1β and IL-6 expressions. Regarding the identity of the isolated bacteria, Pseudomonas spp. were most frequently detected. The results of this study have revealed the incidence and characteristics of porcine mammary lesions.

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.

Effects of indole-3-carbinol on steroid hormone profile and tumor progression in a mice model of canine inflammatory mammarycancer

Background

Indole-3-carbinol, derived from Cruciferous vegetables is an estrogen receptor antagonist considered a preventive agent that is naturally present in diet. There are no previous studies on its effects in human inflammatory breast cancer or canine inflammatory mammary cancer that is the most aggressive type of breast cancer.

Methods

The aim of this study was to analyze the effect of indole-3-carbinol on a SCID mice xenograft model of canine inflammatory mammary cancer, using equivalent human oral dose as a preventive therapy in humans for 3 weeks.

Results

Indole-3-carbinol treatment decreased tumor proliferation and increased apoptosis, although tumor embolization and liver metastasis were observed in some animals. There was a characteristic subpopulation of lipid-rich cells and increased contents of select steroid hormones in tumor homogenates and serum.

Conclusions

Our data reveal for the first time that the ingestion of indole-3-carbinol, as administered, diminishes proliferation and increases apoptosis of tumor cells in an experimental model of inflammatory breast cancer, although this effect could not be enough to avoid the appearance of tumor embolization and metastasis. Future clinical trials will be needed to clarify the usefulness of indole-3-carbinol in this cancer and to understand the molecular mechanisms involved.

Comparative aspects of canine and human inflammatory breast cancer

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.

In vitro and in vivo effect of flutamide on steroid hormone secretion in canine and human inflammatory breast cancer cell lines

The aim was to study the effects of flutamide on cell proliferation, in vivo tumour growth and steroid production in canine and human IBC cell lines. IPC-366 and SUM149 cell cultures were exposed to flutamide concentrations for 72 hours. Additionally, IPC-366 and SUM149 xenotransplanted mice were treated subcutaneously with flutamide 3 times a week for 2 weeks. Steroid hormones determination in culture media, serum and tumour homogenates (pregnenolone, progesterone, androstenedione, testosterone, dihydrotestosterone, 17β-oestradiol and oestrone sulphate) were assayed by EIA. in vitro cell proliferation percentages showed a decrease in all flutamide dosages in IPC-366 and SUM149. in vivo flutamide reduced tumour size by 55% to 65%, and metastasis rates decreased. In treated groups, androgen levels in culture media, serum and tumour homogenates were increased as oestrogen levels decreased. These results suggest that flutamide treatment inhibits cell proliferation and promotes tumour reduction by increasing androgen levels and also support future therapy approaches.

Mammary gland tumors in a male Cocker Spaniel

BACKGROUND

Mammary gland tumors are the most common tumors in sexually intact female dogs; however, they are rare in male dogs. This study was conducted to investigate the relationship between sexual hormones and mammary gland tumors in a male dog.

CASE PRESENTATION

A 13-year-old, intact male Cocker Spaniel presented to the Veterinary Teaching Hospital of Kangwon National University, Republic of Korea, with an acute right ruptured caudal abdominal mass. Physical examination revealed a 14 × 14 cm ruptured mass in the right caudal abdomen, as well as a 1.5 × 1.5 cm mass in the first right mammary gland. The estrogen and progesterone concentrations in serum were within normal levels. Total mastectomy was done on the right side mammary glands. Following surgery, the site was fully recovered; however, a mass that had grown to 2 × 2 cm was found in the left fifth mammary gland and a testis tumor was also found over the period of 4 months. Mastectomy was performed on the left caudal mammary gland and castration was also performed. After the final surgery, the dog fully recovered. Histopathological examination of all three masses revealed high grade mammary adenocarcinoma in the mammary gland and the testis was diagnosed as Leydig cell adenoma. Immunohistochemical analysis revealed that the estrogen and progesterone receptors were expressed on limited cells in mammary and testis tumors.

CONCLUSION

The results of this study suggest that mammary tumors and testes tumors can occur in male dogs without relationship to female sexual hormone.

Usefulness of immunohistochemical indicators for diagnosis and prognosis of poorly differentiated tumours

Immunohistochemical studies have become an indispensable element of establishing the correct histopathological diagnosis of poorly differentiated lesions, proving particularly suitable, and occasionally indispensable, for diagnosis of poorly differentiated neoplastic tumours. Knowledge of the mechanism of action and normal reaction of individual proteins is required in selection of the antibody pattern for a given tissue and in evaluation of the obtained results. This paper aims to promote the application of immunohistochemical techniques in routine diagnosis, especially in cases of poorly differentiated or undifferentiated tumours.

Steroid Tumor Environment in Male and Female Mice Model of Canine and Human Inflammatory Breast Cancer

Canine inflammatory mammary cancer (IMC) shares clinical and histopathological characteristics with human inflammatory breast cancer (IBC) and has been proposed as a good model for studying the human disease. The aim of this study was to evaluate the capacity of female and male mice to reproduce IMC and IBC tumors and identify the hormonal tumor environment. To perform the study sixty 6–8-week-old male and female mice were inoculated subcutaneously with a suspension of 10⁶IPC-366 and SUM149 cells. Tumors and serum were collected and used for hormonal analysis. Results revealed that IPC-366 reproduced tumors in 90% of males inoculated after 2 weeks compared with 100% of females that reproduced tumor at the same time. SUM149 reproduced tumors in 40% of males instead of 80% of females that reproduced tumors after 4 weeks. Both cell lines produce distant metastasis in lungs being higher than the metastatic rates in females. EIA analysis revealed that male tumors had higher T and SO4E1 concentrations compared to female tumors. Serum steroid levels were lower than those found in tumors. In conclusion, IBC and IMC male mouse model is useful as a tool for IBC research and those circulating estrogens and intratumoral hormonal levels are crucial in the development and progression of tumors.

Profile of Steroid Receptors and Increased Aromatase Immunoexpression in Canine Inflammatory Mammary Cancer as a Potential Therapeutic Target

Canine inflammatory mammary cancer (IMC) has been proposed as a model for the study of human inflammatory breast cancer (IBC). The aims of this study were to compare the immunohistochemical expression of aromatase (Arom) and several hormone receptors [estrogen receptor α (ERα), estrogen receptor β (ERβ), progesterone receptor (PR) and androgen receptor (AR)], in 21 IMC cases vs 19 non-IMC; and to study the possible effect of letrozole on canine IMC and human inflammatory breast cancer (IBC) in vitro using IPC-366 and SUM-149 cell lines. Significant elevations of the means of Arom Total Score (TS), ERβ TS and PR TS were found in the IMC group (p = 0.025, p = 0.038 and p = 0.037, respectively). Secondary IMC tumours expressed higher levels of Arom than primary IMC (p = 0.029). Non-IMC PR- tumours contained higher levels of Arom than non-IMC PR+ tumours (p = 0.007). After the addition of letrozole, the number of IMC and IBC cells dropped drastically. The overexpression of Arom found and the results obtained in vitro further support canine IMC as a model for the study of IBC and future approaches to the treatment of dogs with mammary cancer, and especially IMC, using Arom inhibitors.

Sequence to structure approach of estrogen receptor alpha and ligand interactions

Estrogen receptors (ERs) are steroid receptors located in the cytoplasm and on the nuclear membrane. The sequence similarities of human ERα, mouse ERα, rat ERα, dog ERα, and cat ERα are above 90%, but structures of ERα may different among species. Estrogen can be agonist and antagonist depending on its target organs. This hormone play roles in several diseases including breast cancer. There are variety of the relative binding affinity (RBA) of ER and estrogen species in comparison to 17β-estradiol (E2), which is a natural ligand of both ERα and ERβ. The RBA of the estrogen species are as following: diethyl stilbestrol (DES)>hexestrol>dienestrol>17β-estradiol (E2)>17-estradiol>moxestrol>estriol (E3)>4-OH estradiol>estrone-3-sulfate. Estrogen mimetic drugs, selective estrogen receptor modulators (SERMs), have been used as hormonal therapy for ER positive breast cancer and postmenopausal osteoporosis. In the postgenomic era, in silico models have become effective tools for modern drug discovery. These provide three dimensional structures of many transmembrane receptors and enzymes, which are important targets of de novo drug development. The estimated inhibition constants (Ki) from computational model have been used as a screening procedure before in vitro and in vivo studies.

Effect of Ovariohysterectomy at the Time of Tumor Removal in Dogs with Mammary Carcinomas: A Randomized Controlled Trial

Background

Ovarian hormones play crucial roles in mammary carcinogenesis. However, whether ovarian ablation by ovariohysterectomy (OHE) improves the prognosis in dogs with mammary carcinomas is unclear.

Objectives

Determine if OHE at the time of mastectomy improves the prognosis in dogs with mammary carcinomas and evaluate if hormonal factors influence the effect of OHE.

Animals

Sixty intact dogs with mammary carcinomas.

Methods

Dogs were randomly assigned in a 1 : 1 ratio to undergo OHE (n = 31) or not (n = 29) at the time of tumor removal. Peri‐surgical serum estradiol (E2) and progesterone concentrations were measured, tumor diagnosis was confirmed histologically, and tumor estrogen and progesterone receptor status was immunohistochemically determined. The dogs were monitored for recurrence and metastases every 3‐4 months for at least 2 years. Uni‐ and multivariable survival analyses were performed with relapse and all‐cause death as endpoints in addition to univariable subgroup analyses.

Results

Overall, OHE did not significantly decrease hazard of relapse (hazard ratio [HR], 0.64; P = .18) or all‐cause death (HR, 0.87; P = .64) in univariable analyses. In multivariable analysis OHE did not significantly influence the hazard of relapse (HR, 0.54; P = .12), but an interaction effect was identified between ER status and E2 (P = .037). Subgroup analysis identified decreased hazard of relapse in the OHE group compared to the non‐OHE group in the subsets of dogs with increased E2 (HR, 0.22; P = .012) or grade 2 tumors (HR, 0.26; P = .02).

Conclusion

Dogs with grade 2, ER‐positive tumors, or with increased peri‐surgical serum E2 concentration represent a subset of dogs with mammary carcinomas likely to benefit from OHE.

Endocrine control of canine mammary neoplasms: serum reproductive hormone levels and tissue expression of steroid hormone, prolactin and growth hormone receptors

Background

Neoplasms of the mammary gland are among the most common diseases in female domestic dogs (Canis familiaris). It is assumed that reproductive hormones influence tumorigenesis in this species, although the precise role of the endocrine milieu and reproductive state is subject to continuing discussion. In line with this, a recent systematic review of available data on the development of mammary neoplasms revealed weak evidence for risk reduction after neutering and an effect of age at neutering. Investigation of several hormone receptors has revealed decreased expression of estrogen receptor-alpha (ERα, ESR1), progesterone (P4) receptor (PGR), prolactin (PRL) receptor (PRLR) and growth hormone receptor (GHR) associated with neoplastic differentiation of mammary tissues. In other studies, increased levels of estrogens, progesterone and prolactin were found in serum and/or tissue homogenates of dogs with malignant neoplasms. However, the association between these entities within one animal population was never previously examined. Therefore, this study investigated the association between circulating serum concentrations of estradiol-17β, progesterone and prolactin, and gene expression of ERα (ESR1), ERβ (ESR2), PGR, PRLR, PRL and GHR, with respect to reproductive state (spayed vs. intact) and cycle stage (anestrus vs. diestrus). Additionally, the expression of E-cadherin (CDH-1) was evaluated as a possible indicator of metastatic potential.

Results

For all receptors, the lowest gene expression was found in malignant tumors compared to normal tissues of affected dogs. Steroid levels were not influenced by their corresponding receptor expression in mammary neoplasms, but increased PRL levels were negatively associated with low PRLR gene expression in malignant tumors. The expression of CDH-1 was influenced by tumor malignancy and cycle stage, i.e., the highest gene expression was found in benign mammary tumors in diestrous dogs compared to normal and malignant mammary tissues of anestrous and spayed dogs.

Conclusions

Herein, it has been confirmed that transformation towards malignant neoplasms is associated with significant reduction of gene expression of particular hormone receptors. Only PRLR in malignant tumors seems to be influenced by circulating PRL levels. In dogs, CDH-1 can be used as a prognostic factor; its expression, however, in benign tumors is influenced by cycle stage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0546-y) contains supplementary material, which is available to authorized users.

Serum and Tissue Steroid Hormone Levels in Canine Mammary Tumours: Clinical and Prognostic Implications

Hormonal dependency of canine mammary tumours (CMT) has been studied over the last few decades. However, studies assessing the prognostic and predictive potential of serum and/or tissue steroid hormone levels are still scarce in CMT. To the best of our knowledge, this is the first report relating serum and tissue levels of steroid hormones and prognosis in dogs. Serum and tumour tissue from 45 female dogs with spontaneous CMT were included in the study. Moreover, serum and normal mammary tissue from 13 healthy female dogs were also included as controls. Steroid hormones were determined by competitive enzyme immunoassay. Overall, levels of steroid hormones in serum and tissue homogenates were significantly different between malignant and benign mammary tumours (p < 0.01), except for progesterone (P4) serum levels that revealed no statistical differences between groups. In malignant tumours, oestrone sulphate (SO4E1), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T) and P4 elevated tissue concentrations were significantly associated with tumour relapse and/or distant metastasis during follow-up. A significant association was found between elevated tissue SO4E1 (p = 0.003), 17β-oestradiol (E2) (p = 0.036), DHEA (p = 0.022), A4 (p = 0.001) and P4 (p = 0.013) concentrations and shorter disease-free survival and overall survival in female dogs with malignant mammary tumours. The high levels of tissue steroids found in cases of poor prognosis open the possibility of additional new therapeutic approaches. Future clinical trials will be needed to clarify the usefulness of targeting steroid hormones in the treatment of this neoplastic disease.

Fetal Microchimerism in Cancer Protection and Promotion: Current Understanding in Dogs and the Implications for Human Health

Fetal microchimerism is the co-existence of small numbers of cells from genetically distinct individuals living within a mother's body following pregnancy. During pregnancy, bi-directional exchange of cells occurs resulting in maternal microchimerism and even sibling microchimerism in offspring. The presence of fetal microchimerism has been identified with lower frequency in patients with cancers such as breast and lymphoma and with higher frequency in patients with colon cancer and autoimmune diseases. Microchimeric cells have been identified in healing and healed tissues as well as normal and tumor tissues. This has led to the hypothesis that fetal microchimerism may play a protective role in some cancers and may provoke other cancers or autoimmune disease. The long periods of risk for these diseases make it a challenge to prospectively study this phenomenon in human populations. Dogs get similar cancers as humans, share our homes and environmental exposures, and live compressed life-spans, allowing easier prospective study of disease development. This review describes the current state of understanding of fetal microchimerism in humans and dogs and highlights the similarities of the common cancers mammary carcinoma, lymphoma, and colon cancer between the two species. Study of fetal microchimerism in dogs might hold the key to characterization of the type and function of microchimeric cells and their role in health and disease. Such an understanding could then be applied to preventing and treating disease in humans.

New method for recognition of sterol signalling molecules: methinium salts as receptors for sulphated steroids

In this work, we studied indolium and benzothiazolium pentamethine salts 1-3 as novel type of receptors for the recognition of sulphated signalling molecules (sulphated steroids: oestrone, pregnenolone and cholesterol sulphate). A recognition study was performed in an aqueous medium (1mM phosphate buffer (H2O:MeOH; 99:1 (v/v))) at pH 7.34. The tested salts displayed a high affinity for these sulphated analytes, mainly for cholesterol sulphate. However, no interaction between the salts and control, non-sulphated sterol analytes (cholesterol and bile acid) was observed. The highest affinity for the sulphated steroids was observed for benzothiazole salt 1. This salt also displayed different spectral behaviour from that observed for carbocyanine salts 2 and 3. In this presence of cholesterol sulphate, benzothiazole salt 1 displayed significant spectral changes depending on the medium used: a blue shift in the aqueous medium and a red shift in the methanolic one (H2O:MeOH; 2:1 (v/v)). Subsequently preliminary in vivo study showed that, salt 1 significantly inhibits a growth of breast carcinoma on Nu/nu mice model.

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.

Increased levels of interleukins 8 and 10 as findings of canine inflammatory mammary cancer

Inflammatory mammary cancer (IMC) is a distinct form of mammary cancer that affects dogs and women [in humans, IMC is known as inflammatory breast cancer (IBC)], and is characterized by a sudden onset and an aggressive clinical course. Spontaneous canine IMC shares epidemiologic, histopathological and clinical characteristics with the disease in humans and has been proposed as the best spontaneous animal model for studying IBC, although several aspects remain unstudied. Interleukins (ILs) play an important role in cancer as potential modulators of angiogenesis, leukocyte infiltration and tumor growth. The aims of the present study were to assess serum and tumor levels of several ILs (IL-1α, IL-1β, IL-6, IL-8 and IL-10) by enzyme-immunoassay in dogs bearing benign and malignant mammary tumors, including dogs with IMC, for a better understanding of this disease. Forty-eight dogs were prospectively included. Animals consisted of 7 healthy Beagles used as donors for normal mammary glands (NMG) and serum controls (SCs), 10 dogs with hyperplasias and benign mammary tumors (HBMT), 24 with non-inflammatory malignant mammary tumors (non-IMC MMT) and 7 dogs with clinical and pathological IMC. IL-8 (serum) and IL-10 (serum and tissue homogenate) levels were higher in the dogs with IMC compared with the non-IMC MMT group. ILs were increased with tumor malignancy as follows: in tumor homogenates IL-6 levels were higher in malignant tumors (IMC and non-IMC MMT) versus HBMT and versus NMG and tumor IL-8 was increased in malignant tumors versus NMG; in serum, IL-1α and IL-8 levels were higher in the malignant groups respect to HBMT and SCs; interestingly, IL-10 was elevated only in the serum of IMC animals. To the best of our knowledge, this is the first report that analyzes ILs in IMC and IL-10 in canine mammary tumors. Our results indicate a role for IL-6, IL-8 and IL-10 in canine mammary malignancy and specific differences in ILs content in IMC versus non-IMC MMT that could have future diagnostic and therapeutic implications, to be confirmed in a larger series of IMC cases. These results help to support the validity of the IMC canine model for the study of human IBC and provide insight into this uncommon malignancy in dogs.

Expressão gênica dos REα, REβ e PR em tumores mamários de cadelas por meio do q-PCR

A expressão de receptores de estrógeno (ER) e progesterona (PR) por meio da técnica de q-PCR foi avaliada em 26 cadelas portadoras de neoplasias mamárias e cinco cadelas sem afecções mamárias (grupo controle). Os resultados mostraram que os três grupos de animais estudados - com tumor maligno ou benigno e controle - expressaram receptores de estrógeno alfa, beta e progesterona. A quantificação relativa mostrou tendência para uma expressão maior de receptores no grupo controle e menor no grupo de animais com neoplasias malignas. Além disso, observou-se expressão maior de ERα em relação ao ERβ, e as neoplasias malignas de origem mista apresentaram maiores concentrações dos receptores PR, ERα e ERβ que as neoplasias de origem epitelial.

An immunohistochemical study on the expression of sex steroid receptors in canine mammary tumors

Steroid hormones are found to play a major role in the genesis and progression of mammary tumors. The aim of this study was to immunohistochemically detect the presence of estrogen receptor alpha (ER α ), estrogen receptor beta (ER β ), and progesterone receptor (PR) and also to study the association between these markers in 29 cases of benign (11) and malignant (18) canine mammary tumors. ER α immunostaining was noticed in only one case of carcinosarcoma specifically in the nuclei of epithelial and a few myoepithelial cells. ER β immunostaining was noticed in the nuclei and cytoplasm of epithelial cells and smooth muscles lining the blood vessels. Immunoexpression of ER β was 82% in benign tumors and 78% in malignant tumors. PR immunostaining was expressed in the nuclei of epithelial cells in both benign and malignant tumors. Among the 15 PR+ cases, 6 (55%) were of benign type, and 9 (50%) were of malignant type. The most common group of hormone receptor was the ER α -/PR+/ER β + (46%) in benign tumors and ER α -/PR-/ER β + (38%) in malignant tumors. Although there was no significant association between ER α and PR with ER β , the findings indicated that ER β was consistently expressed in both benign and malignant tumors, irrespective of ER α and PR status.

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.

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.

Histological, Immunohistological, and Ultrastructural Description of Vasculogenic Mimicry in Canine Mammary Cancer

Canine inflammatory mammary cancer (IMC) and human inflammatory breast cancer (IBC) are the most aggressive and lethal type of mammary cancer in female dogs and in women. The generation of microvascular channels by malignant tumor cells (endothelial-like cells [ELCs]) without endothelial cell participation (vasculogenic mimicry) has been reported in human breast cancer, including IBC, and is considered a new type of tumor angiogenesis. The aim of this study was to investigate the presence of ELCs in highly malignant canine mammary tumors (IMC and non-IMC) by histology, inmunohistochemistry (pancytokeratin, cytokeratin 14, vimentin, actin, desmin, vWF, CD31, and CD34), and electron microscopy. This retrospective study included 21 female dogs with diagnoses of IMC and 20 animals with metastatic grade III noninflammatory malignant mammary tumors (MMT). IMC tumors (33.33%) and MMT (5%) showed ELCs forming structures similar to small capillaries. The histological, immunohistochemical (positive to AE1/AE3 and cytokeratin 14, mostly negative to endothelial markers), and ultrastructural characteristics of these cells indicated vasculogenic mimicry. The higher frequency of this phenomenon in inflammatory versus noninflammatory canine mammary cancer is in agreement with previous studies in experimental and spontaneous human IBC, and it could be in relation with the extremely high lymphangiogenic capacity and metastatic lymphangiotropism characteristics of inflammatory breast cancer.

Survival time of dogs with inflammatory mammary cancer treated with palliative therapy alone or palliative therapy plus chemotherapy

Seven of 30 female dogs diagnosed with inflammatory mammary cancer were given chemotherapy and palliative treatment, and the other 23 received only palliative treatment. The median survival time of the seven dogs given chemotherapy was 57 days, compared with 35 days for the 23 given only palliative treatment.

Positive correlation of steroid hormones and EGF in canine mammary cancer

There are no published studies focused on the potential crosstalk between steroid hormones and EGF in canine mammary tumourigenesis. The objective was to investigate the role of EGF in canine mammary tumours (CMT) and the relationship with steroid hormones. Sixty-three CMT (39 malignant including 10 inflammatory mammary carcinomas (IMC); 19 benign and 5 dysplasias), and 13 normal mammary glands from dogs without history of neoplastic disease were analysed. Levels of EGF and steroid hormones [progesterone (P4); 17beta-estradiol (E2); androstenedione (A4) and dehydroepiandrosterone (DHEA)], were analysed by EIA in CMT homogenates. Levels of EGF were significantly higher in malignant compared with benign tumours, dysplasias and normal mammary glands (p<0.001). IMC presented the highest EGF levels, with statistical significant difference between IMC and non-IMC cases (p<0.05). Steroid hormone levels were also significantly higher in malignant tumours compared with benign tumours, dysplasias and normal mammary glands (p<0.001). In malignant tumours (non-IMC and IMC), a strong correlation was observed between EGF and: P4 (r=0.452; p=0.003); E2 (r=0.624; p=0.023); A4 (r=0.496; p=0.038); DHEA (r=0.431; p=0.005). These results suggest that EGF is implicated in canine mammary tumourigenesis. The positive correlation observed, opens an interesting perspective of interaction that should be further investigated.

MicroRNA expression in canine mammary cancer

MicroRNAs (miRNAs) are 18-22-nt noncoding RNAs that are involved in post-transcriptional regulation of genes. Oncomirs, a subclass of miRNAs, include genes whose expression, or lack thereof, are associated with cancers. Until the last decade, the domestic dog was an underused model for the study of various human diseases that have genetic components. The dog exhibits marked genetic and physiologic similarity to the human, thereby making it an excellent model for study and treatment of various hereditary diseases. Furthermore, because the dog presents with distinct, spontaneously occurring mammary tumors, it may serve as a model for genetic analysis and treatments of humans with malignant breast tumors. Because miRNAs have been found to act as both tumor suppressors and oncogenes in several different cancers, expression patterns of ten miRNAs (miR-15a, miR-16, miR-17-5p, miR-21, miR-29b, miR-125b, miR-145, miR-155, miR-181b, let-7f) known to be associated with human breast cancers were compared to malignant canine mammary tumors (n = 6) and normal canine mammary tissue (n = 10). Resulting data revealed miR-29b and miR-21 to have a statistically significant (p < 0.05 by MANOVA analysis) upregulation in cancerous samples. The ten canine miRNAs follow the same pattern of expression as in the human, except for miR-145 which does not show a difference in expression between the normal and cancerous canine samples. In addition, when analyzed according to specific cancer phenotypes, miR-15a and miR-16 show a significant downregulation in canine ductal carcinomas while miRsR-181b, -21, -29b, and let-7f show a significant upregulation in canine tubular papillary carcinomas.

Estrogens metabolism associated with polymorphisms: influence of COMT G482a genotype on age at onset of canine mammary tumors

Catechol-O-methyltransferase (COMT) is an important enzyme participating in inactivation of carcinogenic oestrogen metabolites. In humans there is a single nucleotide polymorphism in COMT gene (COMT val158met) that has been associated with an increased risk for developing breast cancer. In dogs, there is a single nucleotide polymorphism in COMT gene (G482A), but its relation with mammary carcinogenesis has never been investigated. The aim of this study was to focus on the evaluation of such polymorphism as a risk factor for the development of mammary tumors in bitches and on the analysis of its relationship with some clinicopathologic features (dog's age and weight, number and histologic type of the lesions, lymph node metastasis) of canine mammary neoplasms. A case-control study was conducted analyzing 90 bitches with mammary tumors and 84 bitches without evidence of neoplastic disease. The COMT G482A polymorphism was analyzed by PCR-RFLP. We found a protective effect of the polymorphism in age of onset of mammary tumors, although we could not establish a significant association between COMT genotype and other clinicopathologic parameters nor with mammary tumor risk overall. Animals carrying the variant allele have a threefold likelihood of developing mammary tumors after 9 years of age in comparison with noncarriers. The Kaplan-Meier method revealed significant differences in the waiting time for onset of malignant disease for A allele carrier (12.46 years) and noncarrier (11.13 years) animals. This investigation constitutes the first case-control study designed to assess the relationship between polymorphic genes and mammary tumor risk in dogs. Our results point to the combined effect of COMT genotype with other genetic and/or environmental risk factors as important key factors for mammary tumor etiopathogenesis.

Crosstalk between GH/IGF-I axis and steroid hormones (progesterone, 17beta-estradiol) in canine mammary tumours

Growth hormone (GH), insulin-like growth factor I (IGF-I), progesterone (P4) and 17beta-estradiol (17-E2) concentrations have been studied in 84 mammary tumours (44 dysplasias and benign tumours and 40 malignant neoplasias) from 33 female dogs. Thirteen normal mammary glands from 80 healthy female dogs were also analysed as controls. GH concentrations were determined in mammary homogenates by radio-immunoassay. IGF-I, P4 and 17-E2 tissue levels were determined by enzyme-immunoassay (EIA) techniques. The potential correlations between GH/IGF-I concentrations and P4 and 17-E2 mammary tissue levels were investigated. Tissue GH (p<0.01) and IGF-I concentrations (p<0.01) were significantly higher in malignant tumours than in benign neoplasms. Likewise, malignant tumours were the mammary lesions that displayed the highest P4 and 17-E2 tissue levels. Strong correlations between GH/IGF-I (n=84; r=0.436; p<0.001), P4/GH (n=84; r=0.562; p<0.001) and 17-E2/IGF-I (n=84; r=0.638; p<0.001) were observed in tumoral tissue homogenates. Our study provides evidence that P4 might increase autocrine GH production which might directly stimulate local or systemic IGF-I secretion. Additionally, the IGF-I effect might be influenced by local levels of 17-E2. These results suggest that all these hormones and factors might act as local growth factors stimulating the development and/or maintenance of canine mammary tumours in an autocrine/paracrine manner.

Steroid pathway and oestrone sulphate production in canine inflammatory mammary carcinoma

Spontaneous canine mammary inflammatory carcinoma (IMC) shares epidemiologic, histopathologic and clinical characteristics with the inflammatory breast carcinoma (IBC) disease in humans. We have analysed the steroids levels in serum and in tissue homogenates of IMC, the expression of two of their receptors (androgen and beta-estrogen) and of three enzymes included in the steroidogenesis pathway (aromatase (CYP19A1), steroid sulphatase (STS) and estrogen sulfotransferase (EST)) trying to explain the specific accumulation of steroids in IMC tissues generating deposits in the form of lipid droplets whose presence can be attributed to steroids secreted by IMC cells. According to our working hypothesis, oestrone sulphate would be the main component of these lipid droplets. The presence of these steroid deposits would contribute to the intense proliferation and invasive behaviour of IMC and IBC, although their involvement in angiogenesis is yet to be demonstrated.