Exploring the role of microRNAs as diagnostic and prognostic biomarkers in canine mammary tumors

Canine mammary tumors (CMTs) represent a significant health concern in dogs, with a high incidence among intact female dogs. CMTs are a promising comparative model for human breast cancer, due to sharing several pathophysiological features. Additionally, CMTs have a strong genetic correlation with their human counterpart, including the expression of microRNAs (miRNAs). MiRNAs are a class of non-coding RNAs that play important roles in post-translational regulation of gene expression, being implicated in carcinogenesis, tumor progression, and metastasis. Moreover, miRNAs hold promise as diagnostic, prognostic, and metastatic biomarkers. Understanding the molecular mechanisms underlying CMTs is crucial for improving diagnosis, prognosis, and monitoring of treatments. Herein, we provide a comprehensive overview of the current knowledge on miRNAs in CMTs, highlighting their roles in carcinogenesis and their potential as biomarkers. Additionally, we highlight the current limitations and critically discuss the overarching challenges in this field, emphasizing the need for future research to translate miRNA findings into veterinary clinical practice.

Vitamin D status in female dogs with mammary gland tumors

BACKGROUND

Little information exists about vitamin D status in bitches with mammary tumors.

OBJECTIVES

To determine whether low plasma vitamin D concentrations are found in bitches with mammary tumors.

ANIMALS

Eighty-five client-owned bitches with mammary tumors (n = 21 benign, n = 64 malignant) and 39 age-matched healthy bitches.

METHODS

Case-control study. Plasma ionized and total calcium, phosphorus, magnesium, urea, creatinine, albumin, total proteins, alanine aminotransferase, alkaline phosphatase, parathyroid hormone (PTH), calcitriol (1,25-dihydroxyvitamin D), and 25-hydroxyvitamin D concentrations were measured in all bitches at the time of clinical diagnosis and before any treatments. Statistical analysis was performed to compare variables among groups (control, benign, and malignant).

RESULTS

No significant differences were found when plasma 25-hydroxyvitamin D concentrations in bitches with malignant (148.9 [59.9] ng/mL) and benign mammary tumors (150.1 [122.3] ng/mL) were compared with control group (129.9 [54.5] ng/mL). Parathyroid hormone was significantly higher in bitches with malignant (19.9 [20.5] pg/mL), and benign mammary tumors (14.6 [14.9] pg/mL) compared with control group (7.5 [7.5] pg/mL; P < .01). Only the presence of mammary tumors (P < .01) and age (P = .04; adjusted R2 = .22) was significant in predicting PTH.

CONCLUSIONS

Bitches with mammary tumors do not have low 25-hydroxyvitamin D concentrations thus vitamin D supplementation is unlikely to be useful for prevention of mammary tumors in bitches.

Studies on the association of malondialdehyde as a biomarker for oxidative stress and degree of malignancy in dogs with mammary adenocarcinomas

BACKGROUND

Mammary adenocarcinomas are one of the most common tumour diseases in bitches. The relationship between oxidative stress and the degree of malignancy of the tumour has not been sufficiently researched in veterinary medicine.

OBJECTIVES

The main objective was to investigate the potential role of MDA as a practice-relevant biomarker for the assessment of systemic oxidative stress and to determine whether this parameter can indicate the malignancy grade of a mammary adenocarcinoma.

METHODS

In the present pilot study, MDA plasma concentrations were analysed in 55 bitches with (n = 28) and without (n027) malignant adenocarcinomas of the mammary gland using two different measurement methods and the relationship to tumour size was investigated.

RESULTS

The mean MDA concentration measured by enzyme-linked immunosorbent assay (ELISA) was 289 ng/mL (range 365-634 ng/mL) in dogs with grade 1 adenocarcinoma (n = 13), 288.5 ng/mL (range 85-752 ng/mL) in dogs with grade 2 adenocarcinoma (n = 10), 332 ng/mL (range 239-947 ng/mL) in dogs with grade 3 (n = 5) adenocarcinoma and 293 ng/mL (range 175-549 ng/mL) in dogs without a mammary tumour (n = 27). When MDA was measured by HPLC, the average MDA concentration in the study group (n = 11) was 0.24 µmol/L (range 0.16-0.37) and that of the control group (n = 15) was 0.27 µmol/L (range 0.16-1.62). Thus, there were no significant differences between the study group with malignant adenocarcinomas and the control group in both examination methods (p > 0.05). Furthermore, there was no correlation between the MDA concentrations and the approximate volume of the mammary tumour.

CONCLUSION

The results highlight the challenges of providing a prognosis for the malignancy of a mammary adenocarcinoma based on MDA concentrations in plasma using ELISA or HPLC. As a result, histopathological examination remains the gold standard for diagnosing and differentiating adenocarcinomas of the mammary gland.

Domestic dogs as environmental sentinel in comparative toxicologic pathology: Assessment of metals and rare earth elements concentrations in healthy and neoplastic mammary glands

Quantification of trace element concentrations in human and animal tissues has acquired great importance in the last few years, considering the pivotal role of these elements in several physiological and pathological processes. Variations in their concentrations appear to have a role in the development and advancement of diseases in both humans and animals, for example, cancer. The purpose of this study was to investigate the concentration of rare earth elements and metals in healthy and neoplastic Formalin-Fixed Paraffin-Embedded (FFPE) mammary gland tissue of dogs. All samples were processed to have a quantitative determination of inorganic elements including metals of known toxicological interest such as Pb, Cd, Tl, As, Hg, the trace elements Mn, Fe, Co, Cu, Zn, Se, and other elements including Cr, V, Mo, Ni, Sb, W, Sn. Moreover, rare earth elements (REEs) (Sc, Y, Lu, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) were also investigated. Cu and Mo concentrations in mammary cancerous tissue were greater than those in normal mammary glands (p < 0.05). In non-neoplastic tissue increased concentrations of Cd, Co, Ni, Tl, and V were also reported (p < 0.05). The mammary tissue of healthy individuals had greater concentrations of REEs than the neoplastic mammary glands (p < 0.05). The results of our study confirmed differences in mammary inorganic element concentrations between healthy and neoplastic groups, highlighting the potential relevance of these fluctuations in toxicologic pathology.

Spontaneous tumours in dogs: A clinical and pathomorphological study in Kyrgyzstan

The aim of this study is to investigate the correlation between the incidence of spontaneous tumours of various origins and the localisation in dogs with sex, breed, and age factors. A total of 360 tumours with various localisation were studied pathomorphologically. Histopathologic data sets from 360 dog tissue samples were processed and statistically examined. A chi-square test of independence was conducted to examine the relationships among the various levels of the specified variables. Logistic regression models were employed for dichotomous outcomes to ascertain the influence of certain explanatory variables on the tumour types. Characteristic pathomorphological changes observed during examination of dogs with oncologic diseases were determined. The most common neoplasms were mammary tumours, accounting for 43% of the cases. The mammary gland tumours were most common in mongrel dogs (25%), with German Shepherds (17.3%), Poodles, Dachshunds, Central Asian Shepherds (6.7% each), and Rottweilers (5.7%) following. The highest frequency of these tumours appeared at 8 years of age, predominantly originating from the ductal epithelium, which represented 46.4% of all the malignant cases.

AGR2-mediated unconventional secretion of 14-3-3ε and α-actinin-4, responsive to ER stress and autophagy, drives chemotaxis in canine mammary tumor cells

BACKGROUND

Canine mammary tumors (CMTs) in intact female dogs provide a natural model for investigating metastatic human cancers. Our prior research identified elevated expression of Anterior Gradient 2 (AGR2), a protein disulfide isomerase (PDI) primarily found in the endoplasmic reticulum (ER), in CMT tissues, highly associated with CMT progression. We further demonstrated that increased AGR2 expression actively influences the extracellular microenvironment, promoting chemotaxis in CMT cells. Unraveling the underlying mechanisms is crucial for assessing the potential of therapeutically targeting AGR2 as a strategy to inhibit a pro-metastatic microenvironment and impede tumor metastasis.

METHODS

To identify the AGR2-modulated secretome, we employed proteomics analysis of the conditioned media (CM) from two CMT cell lines ectopically expressing AGR2, compared with corresponding vector-expressing controls. AGR2-regulated release of 14-3-3ε (gene: YWHAE) and α-actinin 4 (gene: ACTN4) was validated through ectopic expression, knockdown, and knockout of the AGR2 gene in CMT cells. Extracellular vesicles derived from CMT cells were isolated using either differential ultracentrifugation or size exclusion chromatography. The roles of 14-3-3ε and α-actinin 4 in the chemotaxis driven by the AGR2-modulated CM were investigated through gene knockdown, antibody-mediated interference, and recombinant protein supplement. Furthermore, the clinical relevance of the release of 14-3-3ε and α-actinin 4 was assessed using CMT tissue-immersed saline and sera from CMT-afflicted dogs.

RESULTS

Proteomics analysis of the AGR2-modulated secretome revealed increased abundance in 14-3-3ε and α-actinin 4. Ectopic expression of AGR2 significantly increased the release of 14-3-3ε and α-actinin 4 in the CM. Conversely, knockdown or knockout of AGR2 expression remarkably reduced their release. Silencing 14-3-3ε or α-actinin 4 expression diminished the chemotaxis driven by AGR2-modulated CM. Furthermore, AGR2 controls the release of 14-3-3ε and α-actinin 4 primarily via non-vesicular routes, responding to the endoplasmic reticulum (ER) stress and autophagy activation. Knockout of AGR2 resulted in increased α-actinin 4 accumulation and impaired 14-3-3ε translocation in autophagosomes. Depletion of extracellular 14-3-3ε or α-actinin 4 reduced the chemotaxis driven by AGR2-modulated CM, whereas supplement with recombinant 14-3-3ε in the CM enhanced the CM-driven chemotaxis. Notably, elevated levels of 14-3-3ε or α-actinin 4 were observed in CMT tissue-immersed saline compared with paired non-tumor samples and in the sera of CMT dogs compared with healthy dogs.

CONCLUSION

This study elucidates AGR2's pivotal role in orchestrating unconventional secretion of 14-3-3ε and α-actinin 4 from CMT cells, thereby contributing to paracrine-mediated chemotaxis. The insight into the intricate interplay between AGR2-involved ER stress, autophagy, and unconventional secretion provides a foundation for refining strategies aimed at impeding metastasis in both canine mammary tumors and potentially human cancers.

Domain generalization across tumor types, laboratories, and species - Insights from the 2022 edition of the Mitosis Domain Generalization Challenge

Recognition of mitotic figures in histologic tumor specimens is highly relevant to patient outcome assessment. This task is challenging for algorithms and human experts alike, with deterioration of algorithmic performance under shifts in image representations. Considerable covariate shifts occur when assessment is performed on different tumor types, images are acquired using different digitization devices, or specimens are produced in different laboratories. This observation motivated the inception of the 2022 challenge on MItosis Domain Generalization (MIDOG 2022). The challenge provided annotated histologic tumor images from six different domains and evaluated the algorithmic approaches for mitotic figure detection provided by nine challenge participants on ten independent domains. Ground truth for mitotic figure detection was established in two ways: a three-expert majority vote and an independent, immunohistochemistry-assisted set of labels. This work represents an overview of the challenge tasks, the algorithmic strategies employed by the participants, and potential factors contributing to their success. With an F1 score of 0.764 for the top-performing team, we summarize that domain generalization across various tumor domains is possible with today's deep learning-based recognition pipelines. However, we also found that domain characteristics not present in the training set (feline as new species, spindle cell shape as new morphology and a new scanner) led to small but significant decreases in performance. When assessed against the immunohistochemistry-assisted reference standard, all methods resulted in reduced recall scores, with only minor changes in the order of participants in the ranking.

Risk factor analysis and clinicopathological characteristics of female dogs with mammary tumours from a single-center retrospective study in Poland

This is a comprehensive retrospective study to characterize female dogs with canine mammary tumors (CMTs) using a dataset retrieved from the archives of the Division of Animal Pathology, Institute of Veterinary Medicine in Warsaw, and to identify prognostic factors. Clinical and histopathological data of 1447 dogs with CMTs were included. Malignant tumours were found in 83.3% (n = 1206), benign tumours in 11.7% (n = 169), and non-neoplastic lesions in 5.0% (n = 72) of dogs. Dogs most often had grade II carcinomas (38.2%, 215/562) of a single histological subtype (88.5%, 1281/1447), mostly simple carcinoma (35.3%, 510/1447). Dogs with a median age of 10 years significantly often had larger (≥ 3 cm) and malignant CMTs, whereas intact females had smaller tumours (median size 2.0 cm). However, the threshold value for the age of the dog in the differentiation of malignant and non-neoplastic/benign masses could not be determined. Most females were hormonally active (76.4%, 372/487). Hormonally active dogs significantly more often had multiple tumours. Multiple tumours were significantly smaller (median 2.5 cm) than single ones. Among pedigree dogs, small-breed dogs were mostly recorded (43%, 428/1006). Twelve breeds had an increased risk of CMTs, regardless of tumour behaviour, compared with the theoretical distribution of pedigree dogs in Poland. Four breeds were often affected only by malignant and other four breeds only by non-neoplastic/benign CMT. Large-breed dogs were significantly younger and affected by larger CMT (median 4 cm) compared with small- and medium-breed dogs. Ninety dogs with a malignant CMT and complete records were included in the full analysis of CMT-specific survival (CMT-SS) with a median follow-up time of 20.0 months. We showed that the timing of ovariohysterectomy in relation to mastectomy was significantly associated with grade, CMT-SS, and CMT-related death. We indicated the low diagnostic accuracy of palpation of regional lymph nodes (RLN) in the prediction of their metastatic involvement. By multivariable analysis, dogs with neoplastic emboli, tumour ulceration, and simple or complex carcinoma had a significantly higher risk of local recurrence. Tumour size > 3 cm was as a strong independent predictor of lung metastases. Compared with dogs with an easily separated localized tumour, dogs with a multiple/diffuse malignant CMT pattern had a fivefold higher risk of death. The risk of death was significantly higher in the presence of neoplastic emboli (~ fivefold) and tumour ulceration (~ fourfold). Furthermore, the presence of neoplastic emboli and large tumour size were independent predictors of CMT-related death.

Canine Mammary Tumors: Classification, Biomarkers, Traditional and Personalized Therapies

In recent years, many studies have focused their attention on the dog as a proper animal model for human cancer. In dogs, mammary tumors develop spontaneously, involving a complex interplay between tumor cells and the immune system and revealing several molecular and clinical similarities to human breast cancer. In this review, we summarized the major features of canine mammary tumor, risk factors, and the most important biomarkers used for diagnosis and treatment. Traditional therapy of mammary tumors in dogs includes surgery, which is the first choice, followed by chemotherapy, radiotherapy, or hormonal therapy. However, these therapeutic strategies may not always be sufficient on their own; advancements in understanding cancer mechanisms and the development of innovative treatments offer hope for improved outcomes for oncologic patients. There is still a growing interest in the use of personalized medicine, which should play an irreplaceable role in the research not only in human cancer therapy, but also in veterinary oncology. Moreover, immunotherapy may represent a novel and promising therapeutic option in canine mammary cancers. The study of novel therapeutic approaches is essential for future research in both human and veterinary oncology.

The role of lymph nodes and their drainage in canine mammary gland tumours: Systematic review

Mammary gland tumours are the most common neoplasms in intact bitches. Over the last decades, veterinary oncology has evolved in detecting and determining the lymph nodes to be removed in these patients for an accurate staging and prognosis, as well as to achieve better disease control and higher overall survival time. Our objective was to describe recent advances related to lymphatic drainage in bitches with mammary gland tumours, focusing on surgery, diagnosis, and prognosis. Through a systematic review using PubMed as the database, a thorough multi-step search reduced 316 studies to 30 for analysis. Vital dyes appear to be crucial in reducing the overall surgery time through transoperative staining of the lymph nodes. Imaging contrasts provide information regarding specific tumour drainage; however, there is still little evidence for their use. The axillary and superficial inguinal lymph nodes are well-established as regional lymph nodes of the cranial and caudal mammary glands. In sequence, accessory axillary, medial iliac, popliteal, and sternal lymph nodes should receive attention if they demonstrate contrast drainage, even considering that the literature has not shown a relationship between drainage and metastasis in these cases. In conclusion, recent studies have provided us with more support in regional lymph node excision regarding the TNM staging system. Studies are highly heterogeneous and method comparisons do not fit due to the non-uniformity of samples, materials, and procedures. We suggest further studies with a larger sample size, complete follow-up of patients, contrast use, and lymph node morphological and immunohistochemical analysis.

Profiling canine mammary tumors: A potential model for studying human breast cancer

Despite all clinical progress recorded in the last decades, human breast cancer (HBC) remains a major challenge worldwide both in terms of its incidence and its management. Canine mammary tumors (CMTs) share similarities with HBC and represent an alternative model for HBC. The utility of the canine model in studying HBC relies on their common features, include spontaneous development, subtype classification, mutational profile, alterations in gene expression profile, and incidence/prevalence. This review describes the similarities between CMTs and HBC regarding genomic landscape, microRNA expression alteration, methylation, and metabolomic changes occurring during mammary gland carcinogenesis. The primary purpose of this review is to highlight the advantages of using the canine model as a translational animal model for HBC research and to investigate the challenges and limitations of this approach.

Hormone, Targeted, and Combinational Therapies for Breast Cancers: From Humans to Dogs

Breast cancer (BC) is the most frequent cancer in women. In female dogs, canine mammary gland tumor (CMT) is also the leading neoplasm. Comparative oncology indicates similar tumor behaviors between human BCs (HBCs) and CMTs. Therefore, this review summarizes the current research in hormone and targeted therapies and describes the future prospects for HBCs and CMTs. For hormone receptor-expressing BCs, the first medical intervention is hormone therapy. Monoclonal antibodies against Her2 are proposed for the treatment of Her2+ BCs. However, the major obstacle in hormone therapy or monoclonal antibodies is drug resistance. Therefore, increasing alternatives have been developed to overcome these difficulties. We systemically reviewed publications that reported inhibitors targeting certain molecules in BC cells. The various treatment choices for humans decrease mortality in females with BC. However, the development of hormone or targeted therapies in veterinary medicine is still limited. Even though some clinical trials have been proposed, severe side effects and insufficient case numbers might restrict further explorations. This difficulty highlights the urgent need to develop updated hormone/targeted therapy or novel immunotherapies. Therefore, exploring new therapies to provide more precise use in dogs with CMTs will be the focus of future research. Furthermore, due to the similarities shared by humans and dogs, well-planned prospective clinical trials on the use of combinational or novel immunotherapies in dogs with CMTs to obtain solid results for both humans and dogs can be reasonably anticipated in the future.

Upregulation of miR-21 and pro-inflammatory cytokine genes IL-6 and TNF-α in promoting a pro-tumorigenic microenvironment in canine mammary carcinomas

This study evaluated the gene expression of the pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in canine mammary tumors (CMTs), and correlated them with gene expression of miRNAs expected to regulate the secretion of pro-inflammatory cytokines within the tumor microenvironment (TME). Furthermore, gene expression of cytokines and miRNAs involved in tumor cell proliferation and invasion (i.e. miR-21; miR-124; miR-145) were correlated with tumor proliferation index (Ki67 index) to determine the prognostic value in CMTs. Twenty-six canine mammary samples were used, including 22 CMTs and 4 control samples. MiR-21, IL-6 and TNF-α were upregulated in mammary carcinomas compared with controls (p < 0.05). MiR-146b was downregulated in CMTs compared with control cases (p < 0.05). IL-6 expression showed a significant positive correlation with miR-21 and a negative correlation with miR-146b; while, TNF-α gene expression was positively correlated with miR-21 and miR-145 in mammary carcinomas. In carcinomas, the Ki67 index correlated positively with gene expression of IL-6 and miR-21 and negatively correlated with miR-145 and miR-146b. Specifically, gene expression of IL-6 and miR-21 was positively correlated with ki67 index >33.3%, whereas, expression of miR-145 and miR-146b was negatively correlated with ki67 index <33.3%. Results reinforce the concept of interaction between tumor cells and inflammatory cells within the TME, with a central role of IL-6 and TNF-α. Since the upregulation of miR-21 reflects the gene overexpression of interleukins and the high proliferation index of tumor cells, this miRNA may be considered a biomarker with prognostic value in CMTs.

Is Osteopontin a Good Marker for Bone Metastasis in Canine Mammary Gland Tumor and Prostate Cancer?

Osteopontin (OPN) is a protein synthesized by a large number of cells, and its overexpression has been associated with the development and prognosis of cancer. OPN overexpression has been claimed to be a marker for the development of bone metastasis in human cancers, but no prior research has investigated the association between OPN expression and the metastasis of canine mammary gland tumors (MGTs) and prostate cancer (PC). Therefore, we investigated OPN expression in MGTs and PC samples from 50 canine patients with or without metastasis (bone vs. other sites). Higher OPN expression was detected in primary tumor samples from animals with bone metastasis than in those without bone involvement (p = 0.0321). In MGT samples, a significantly lower survival rate was observed in patients with higher OPN expression (p = 0.0171). In animals with PC, there was a strong trend toward lower survival in animals with positive OPN expression; however, this trend was not statistically significant (p = 0.0779). From these findings, it can be concluded that OPN may be a promising target for future MGTs and PC studies because of its role in enhancing cell invasion and metastasis.

Identifying the Risk Factors for Malignant Mammary Tumors in Dogs: A Retrospective Study

Mammary cancer is one of the main causes of death in female dogs worldwide, considering that many risk factors are involved in its development. This study aimed to elucidate the relationship between epidemiological and clinical risk factors with the histopathological diagnosis of malignant mammary tumors in dogs treated at the Veterinary Hospital of the Federal University of Uberlândia, which has one of the first veterinary oncology services in Brazil. A retrospective matched case-control study was conducted to identify risk factors for the development of malignant mammary tumors in dogs. The variables analyzed were size dog, breed, housing, type of diet, and body score. Potential risk factors were selected by univariate analysis (p < 0.25) before multivariate forward binary logistic regression. The most frequent benign tumor was the benign mixed tumor (35.2%), and the most frequent malignant tumor was the mixed carcinoma (27.4%). Size dog, breed, housing, and overweight are predictors of malignant mammary tumors in dogs. The highest risk of developing malignant mammary tumors is associated with large female dogs, Yorkshire or Poodle breeds, living outside the home, or being overweight.

Prognostic value of different forms of serum MMP-2 and MMP-9 in dogs with mammary tumors; a longitudinal study

Gelatinases (MMP-2 and MMP-9) are related to tumor invasion and metastasis. In humans, the diagnostic value of serum levels of gelatinases has been confirmed in breast cancer, but their diagnostic value in canine mammary tumors is still unknown. This study aimed to determine the serum level of gelatinases in dogs with mammary tumors in order to determine their value in the diagnosis of malignancy or benign tumors and also in predicting the possibility of metastasis and recurrence. Frequent measurement of MMP-2 and MMP-9 by gelatin zymography in serum before and after surgical treatment has not previously been studied for monitoring mammary tumors in dogs. Thus, the serum levels of MMP-2 and MMP-9 in 26 dogs with mammary tumors before surgical treatment and then 1, 4 and 12 months after surgery were evaluated by gelatin zymography. Serum samples of 26 healthy dogs with normal conditions were used as control. Dogs with benign and malignant mammary tumors showed bands of pro-MMP-2, pro-MMP-9 and active MMP-9. However, only pro-MMP-2 and pro-MMP-9 bands appeared in the serum of control group. Our results showed that the presence of active MMP-9, regardless of its level, was prognostically important for metastasis and or recurrence (M/R). However, the presence of active MMP-2 band was more important for M/R than active MMP-9, as its presence coincides with definitive M/R. It seems that serum gelatin zymography could possibly be used at regular intervals before and after surgery to evaluate the probability of M/R in dogs with mammary tumors. More research is needed in this regard.

Neoadjuvant Intratumoral Immunotherapy with Cowpea Mosaic Virus Induces Local and Systemic Antitumor Efficacy in Canine Mammary Cancer Patients

The lack of optimal models to evaluate novel agents is delaying the development of effective immunotherapies against human breast cancer (BC). In this prospective open label study, we applied neoadjuvant intratumoral immunotherapy with empty cowpea mosaic virus-like particles (eCPMV) to 11 companion dogs diagnosed with canine mammary cancer (CMC), a spontaneous tumor resembling human BC. We found that two neoadjuvant intratumoral eCPMV injections resulted in tumor reduction in injected tumors in all patients and in noninjected tumors located in the ipsilateral and contralateral mammary chains of injected dogs. Tumor reduction was independent of clinical stage, tumor size, histopathologic grade, and tumor molecular subtype. RNA-seq-based analysis of injected tumors indicated a decrease in DNA replication activity and an increase in activated dendritic cell infiltration in the tumor microenvironment. Immunohistochemistry analysis demonstrated significant intratumoral increases in neutrophils, T and B lymphocytes, and plasma cells. eCPMV intratumoral immunotherapy demonstrated antitumor efficacy without any adverse effects. This novel immunotherapy has the potential for improving outcomes for human BC patients.

Sirtuin 1 Expression in Canine Mammary Tumors: A Pilot Study

Sirtuin 1 (SIRT1) is a protein involved in aging, cell protection, and energy metabolism in mammals. Recently, SIRT1 has been intensively studied in medical oncology, but the role of SIRT1 is still controversial, as it has been proposed as both an oncogene and a tumor suppressor. The aim of this study is to investigate the expression of SIRT1 by immunohistochemistry in canine mammary tissues, and by Western blot and immunofluorescence analysis in different canine mammary cell lines. Our results showed a decrease in SIRT1 expression from normal mammary gland tissue, and from benign and well-differentiated malignant tumors (G1) to less differentiated ones (G2-G3). Furthermore, a shift in the subcellular localization of SIRT1 from the nucleus to the cytoplasm was observed in less differentiated malignant tumors. However, further studies are needed to investigate the subcellular localization of SIRT1 in canine cancer cells and the role it may play in oncogenesis in animals.

Upregulation of SLUG expression in canine mammary gland tumors and its prognostic significance

BACKGROUND

SLUG (also known as snai2), which is a transcription factor in epithelial-mesenchymal transition (EMT), plays an important role in tumorigenesis. Several human studies have revealed that SLUG expression downregulates E-cadherin activity to induce metastasis and invasion of tumor cells, and its association with tumor mechanisms is under constant evaluation. In clinical veterinary medicine, one study revealed upregulated SLUG expression in canine oral squamous cell carcinoma. However, the association between canine mammary gland tumors (MGT), the most common neoplasm in intact female dogs, and SLUG has not been investigated yet. Therefore, this study aimed to evaluate the differences in SLUG expression among canine normal mammary gland tissue and MGTs using immunohistochemistry. In addition, its prognostic significance was evaluated by analyzing the correlation with the Ki-67 proliferation index and various clinicopathological features.

RESULTS

SLUG expression increased substantially from normal mammary gland tissues to MGTs, especially showing the strongest expression in malignant MGT than in benign MGT. Negative SLUG expression was observed in mostly normal mammary gland tissues, whereas all tissues in malignant MGT showed positive SLUG expression. Furthermore, positive SLUG expression was associated with higher Ki-67 index, larger tumor size (> 3 cm), and metastasis. Kaplan-Meier survival curve analysis revealed that positive SLUG expression was significantly associated with poor overall and disease-free survival.

CONCLUSIONS

These results indicate that SLUG is upregulated in canine MGTs and positive SLUG expression is positively correlated with poor prognosis. Thus, SLUG protein can be a novel biomarker and therapeutic target for canine patients with MGT.

Prognostic Factors for Cancer-Specific Survival and Disease-Free Interval of Dogs with Mammary Carcinomas

Canine mammary tumors (CMTs) are the most diagnosed neoplasms in dogs; however, there are few studies analyzing the influence of epidemiological, clinicopathological, and histopathological data on cancer-specific survival (CSS), disease-free interval (DFI), and overall survival (OS) in a large cohort. To contribute to the understanding of the biological behavior of this neoplasm, 385 cases were analyzed, 89% malignant, 4% benign, and 7% non-neoplastic lesions. Among the dogs diagnosed with malignant neoplasms, 86% had early clinical stages (I-III), while 14% had regional or distant metastasis at the time of diagnosis. Carcinoma in a mixed tumor was the most frequent histological type with 44% of the cases and had the best prognosis. Analyzed factors such as the presence of pseudocyesis, previous history of the disease, advanced clinical stage (IV-V), and presence of ulceration obtained significant results for CSS, DFI, and OS through univariate analysis and had a negative impact on the survival of the patients. Multivariate analysis showed that histological grading and age proved to be the best independent parameters for the prognostic evaluation of CSS and DFI in this study. These factors were also significant in the overall survival analysis. Therefore, these parameters should be considered valuable risk and prognostic factors for CMTs.

Mammary Glands of Women, Female Dogs and Female Rats: Similarities and Differences to Be Considered in Breast Cancer Research

Breast cancer is one of the most common and well-known types of cancer among women worldwide and is the most frequent neoplasm in intact female dogs. Female dogs are considered attractive models or studying spontaneous breast cancer, whereas female rats are currently the most widely used animal models for breast cancer research in the laboratory context. Both female dogs and female rats have contributed to the advancement of scientific knowledge in this field, and, in a "One Health" approach, they have allowed broad understanding of specific biopathological pathways, influence of environmental factors and screening/discovery of candidate therapies. This review aims to clearly showcase the similarities and differences among woman, female dog and female rat concerning to anatomical, physiological and histological features of the mammary gland and breast/mammary cancer epidemiology, in order to better portray breast tumorigenesis, and to ensure appropriate conclusions and extrapolation of results among species. We also discuss the major aspects that stand out in these species. The mammary glands of female dogs and women share structural similarities, especially with respect to the lactiferous ducts and lymphatic drainage. In contrast, female rats have only one lactiferous duct per nipple. A comprehensive comparison between humans and dogs is given a special focus, as these species share several aspects in terms of breast/mammary cancer epidemiology, such as age of onset, hormonal etiology, risk factors, and the clinical course of the disease. Holistically, it is clear that each species has advantages and limitations that researchers must consider during the development of experimental designs and data analysis.

TLRs expression in canine mammary gland neoplasms: a pathological and molecular study

TLRs are a class of PRRs that play a vital role in innate immunity. TLRs are expressed on immune cells and mammary epithelial cells. They can promote tumor growth, angiogenesis, invasion, and viability signaling. The current study aimed to test the correlation between histologic types and grades of neoplasms and TLRs gene expression levels. Twenty-one tissue samples of canine mammary neoplasms were stained with H&E. Then, it evaluated histologic type and grade according to the methods of Goldschmidt et al. and Peña, respectively. We established real-time PCR quantification assays to measure the mRNA abundances of TLRs in normal and neoplastic mammary glands. Profile pattern of TLR 1, 2, 3, 4, 5, 6, and 9 genes expression in canine mammary glands performed in 21 samples of mammary gland neoplasms and three non-neoplastic mammary gland samples from normal dogs. TLR 3, 4, and 9 mRNA overexpression were detected. In addition, tubulopapillary carcinoma grade II, SCC grade III, and carcinoma mixed type grade II demonstrated the highest relative TLR-3, and 9 mRNA expression levels. Complex carcinoma grade I, ductal carcinoma grade II, and anaplastic carcinoma grade II showed the highest relative TLR4 mRNA expression level. Although histopathological characteristics of tumors, including histologic type, grade, and inflammation, influenced TLRs mRNA expression level, such correlation was insignificant (P > 0.05).

Immunohistochemical, pharmacovigilance, and omics analyses reveal the involvement of ATP-sensitive K+ channel subunits in cancers: role in drug-disease interactions

Background: ATP-sensitive-K+ channels (KATP) are involved in diseases, but their role in cancer is poorly described. Pituitary macroadenoma has been observed in Cantu' syndrome (C.S.), which is associated with the gain-of-function mutations of the ABCC9 and KCNJ8 genes. We tested the role of the ABCC8/Sur1, ABCC9/Sur2A/B, KCNJ11/Kir6.2, and KCNJ8/Kir6.1 genes experimentally in a minoxidil-induced renal tumor in male rats and in the female canine breast cancer, a spontaneous animal model of disease, and in the pharmacovigilance and omics databases. Methods: We performed biopsies from renal tissues of male rats (N = 5) following a sub-chronic high dosing topical administration of minoxidil (0.777-77.7 mg/kg/day) and from breast tissues of female dogs for diagnosis (N = 23) that were analyzed by immunohistochemistry. Pharmacovigilance and omics data were extracted from EudraVigilance and omics databases, respectively. Results: An elevated immunohistochemical reactivity to Sur2A-mAb was detected in the cytosol of the Ki67+/G3 cells other than in the surface membrane in the minoxidil-induced renal tumor and the breast tumor samples. KCNJ11, KCNJ8, and ABCC9 genes are upregulated in cancers but ABCC8 is downregulated. The Kir6.2-Sur2A/B-channel opener minoxidil showed 23 case reports of breast cancer and one case of ovarian cancer in line with omics data reporting, respectively, and the negative and positive prognostic roles of the ABCC9 gene in these cancers. Sulfonylureas and glinides blocking the pancreatic Kir6.2-Sur1 subunits showed a higher risk for pancreatic cancer in line with the positive prognostic role of the ABCC8 gene but low risks for common cancers. Glibenclamide, repaglinide, and glimepiride show a lower cancer risk within the KATP channel blockers. The Kir6.2-Sur1 opener diazoxide shows no cancer reactions. Conclusion: An elevated expression of the Sur2A subunit was found in proliferating cells in two animal models of cancer. Immunohistochemistry/omics/pharmacovigilance data reveal the role of the Kir6.1/2-Sur2A/B subunits as a drug target in breast/renal cancers and in C.S.

Expression of type VI collagen α3 chain in canine mammary carcinomas

This study aimed to investigate the expression of type VI collagen α3 chain (COL6a3) in neoplastic cells of canine mammary gland carcinomas (CMGCs) using immunohistochemistry (IHC) and to evaluate the association between COL6a3 expression and tumor histological features, histological grades, and the differentiation status of neoplastic epithelial cells. COL6a3 expression in carcinoma cells was significantly associated with histologically low malignancy and low mitotic indices. In addition, COL6a3+ carcinoma cells were more frequently detected in simple carcinomas (tubular and tubulopapillary types) than in solid carcinomas. These findings indicate that reduced expression of COL6a3 in carcinoma cells contributes to the malignant phenotype in CMGCs. We also showed that COL6a3 expression in the carcinoma cells was more frequently detected in CK19+/CD49f + and/or CK19+/CK5+ tumors. In addition, COL6a3+/CK19+/CD49f + and COL6a3+/CK19+/CK5+ tumors consisted of CK19+/CD49f + and CK19+/CD49f- cells, and CK19+/CK5+ and CK19+/CK5- cells, respectively. Most of these tumors more frequently expressed GATA3, but not Notch1. These results indicate that COL6a3 is expressed in CMGCs containing both luminal progenitor-like and mature luminal-like cells and showing differentiation ability into mature luminal cells. It is possible that COL6 may be involved in the differentiation of luminal progenitor-like carcinoma cells into mature luminal-like carcinoma cells in CMGCs, which may suppresses the development of malignant phenotypes in CMGCs.

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.

Surgical dose and the clinical outcome in the treatment of mammary gland tumours in female dogs: a literature review

Mammary gland tumours are the most frequent tumours in intact female dogs and surgery remains the main treatment modality. Surgery is traditionally performed according to the lymphatic drainage of the mammary glands, but robust evidence is still lacking on what surgical dose is the smallest and results in the best outcome. The objective of the study was to investigate whether choice of surgical dose influences treatment outcome in dogs with mammary tumours and to identify current gaps in research that need to be filled in future studies for identifying the smallest surgical dose with the best possible outcome. Articles for entrance into the study were identified in online databases. Information regarding outcome following use of different surgical doses was extracted for analysis. Also, known prognostic factors were mapped for each study to discuss their impact on treatment outcome. Twelve articles were identified and included. Surgical dose applied ranged from lumpectomy to radical mastectomy. Radical mastectomy was most often analysed [11/12 (92%) articles]. Less invasive surgical doses were used less often in decreasing order of invasiveness. Outcomes analysed were most often survival time [7/12 (58%) articles], frequency of recurrences [5/12 (50%) studies] and time to recurrence [5/12 (42%) studies)]. No studies demonstrated any significant association between surgical dose and outcome. Gaps in the research could be categorised as data that was not available for extraction, for example known prognostic factors. Other factors related to study design were also identified, for example small groups of dogs included into the study. No studies showed a clear benefit of choosing one surgical dose over the other. Choice of surgical dose should be based on known prognostic factors and risks for complications rather than on lymphatic drainage. In future studies all prognostic factors should be included when investigating how choice of surgical dose influences treatment outcome.

Morphological study of apocrine gland tumors in domestic Richardson's ground squirrels (Urocitellus richardsonii)

The morphology of 58 apocrine tumors from 31 domestic Richardson's ground squirrels (Urocitellus richardsonii) was examined, comparing tumor subtypes with clinical information and histological findings. The squirrels included 23 males (74%) and 8 females (26%). Of the 58 tumors, 36 (62%) were located from the cervical skin to the dorsal skin, 17 (29%) were from the perioral region to the cheek, and the location was unrecorded for the remaining 5 squirrels (9%). Histologically, 49 tumors (84%) were apocrine adenocarcinomas, 6 were apocrine adenomas (10%), and 3 were apocrine cysts (5%). The 49 apocrine adenocarcinomas were subclassified as 16 (33%) cystic papillary type, 16 (33%) tubulopapillary type, 12 (24%) solid type, and 5 (10%) micropapillary invasive type. Fisher's exact test revealed correlations between tumor subtypes and tumor diameters, nuclear atypia, tumor margins, vascular invasion, and periodic acid-Schiff (PAS) positivity. This study showed a predominance of apocrine adenocarcinomas with various histological subtypes. In addition, subclassification of these tumors was useful for predicting the biological behavior of apocrine gland tumors in Richardson's ground squirrels.

Validation of p53 Immunohistochemistry (PAb240 Clone) in Canine Tumors with Next-Generation Sequencing (NGS) Analysis

In human medicine, p53 immunohistochemistry (IHC) is a common method that is used for the identification of tumors with TP53 mutations. In veterinary medicine, several studies have performed IHC for p53 in canine tumors, but it is not known how well it actually predicts the mutation. The aim of this study was to estimate the accuracy of the IHC method for p53 (clone PAb240) using a lab-developed NGS panel to analyze TP53 mutations in a subset of malignant tumors in dogs. A total of 176 tumors were analyzed with IHC and then 41 were subjected to NGS analysis; among them, 15 were IHC positive and 26 were negative, and 16 out of 41 (39%) were found to be inadequate for NGS analysis. Excluding the non-evaluable cases at NGS, of the remaining eight IHC-positive cases, six were mutants and two were wild-type. Among the 17 IHC-negative cases, 13 were wild type, and 4 were mutants. The sensitivity was 60%, specificity was 86.7%, and the accuracy was 76%. These results suggest that when using IHC for p53 with this specific antibody to predict mutation, up to 25% wrong predictions can be expected.

Canine mammary carcinoma: current therapeutic targets and future perspectives – a review

Canine mammary carcinoma (CMC) is the most common neoplasm in bitches, and it shares many biological similarities with breast cancer in humans. Drug resistance, high epigenetic mutations, and relapse rates are among the challenges which eventually urge the need for a veterinary oncologist to discover new therapeutic approaches that are more effective and safer. Therefore, in this review, we also cover the current therapeutic strategies from human medicine for the future perspectives of tumor immunotherapy in veterinary medicine. These strategies have great potential to be employed as therapeutic or prophylactic options due to their ability to modulate a specific and potent immune response against CMC. As we acquire a better understanding of canine tumor immunology, we can move towards a brighter prognosis. Additionally, we report on the recent successful studies in breast cancer that may benefit canines as well.

Confirmation of the Prognostic Value of Foxp3+ Cells in Canine Mammary Tumors

Foxp3+ cell counts were evaluated by immunohistochemistry in 59 canine mammary tumors, 20 adenomas, and 39 carcinomas in three different compartments: intratumoral, within the adjacent stroma, and in the distant stroma. Foxp3+ lymphocyte counts were compared with histotype, grading, presence of lymphatic invasion, immunohistochemical expression of estrogen and progesterone receptors, expression of c-erbB-2, and the overall survival (OS). Our findings confirmed that Foxp3+ cells were significantly higher in canine mammary carcinomas compared to adenomas. A significantly higher number of Foxp3+ cells were detected in grade III carcinomas compared to grade II carcinomas, as well as in tumors with lymphatic invasion and loss of ER-expression. Finally, a high number of Foxp3+ cells was associated with poor prognosis. In conclusion, our findings highlighted the association of Foxp3+ lymphocytes with negative clinicopathological features and shorter overall survival (OS), thus confirming the role of Tregs as a negative prognostic marker in canine mammary carcinomas.

Expression and significance of IL-6 and IL-8 in canine mammary gland tumors

Mammary gland tumors are the most common malignant diseases which seriously threaten the health of women and female dogs. There is a lack of an effective tumor marker which can effectively assist in the early diagnosis, and prognosis of mammary gland tumors in veterinary clinical medicine. IL-6, and IL-8 as immunosuppressive factors may stimulate tumor cells growth, contribute to loco-regional relapse and metastasis that might be utilized as a marker for immunity status and monitoring of the course of tumor. The present study aimed to investigate the expression of serum/tissue IL-6, IL-8 and IL-10 in canine mammary gland tumors using Enzyme linked immunosorbent assay(ELISA), Western blot and Immunohistochemistry assay(IHC) to determine whether it is associated with tumor progression. The results showed that levels of IL-6, IL-8 and IL-10 in serum were higher in malignant tumor group than that in benign tumor and control group; the expression levels of IL-6 and IL-8 were significantly elevated in grade III than in grade I and II and was related to metastasis. Likewise, IL-6 and IL-8 were also highly expressed in malignant tumor tissues. Elevated expression of IL-6 was associated with histopathological grade and metastases in malignant tumors. Moreover, high expression of IL-6 occurred in the Basal-like subtypes whereas high expression of IL-8 occurred in the Luminal B subtypes. The results of this study indicated that changes of IL-6 and IL-8 in the tumor microenvironments were closely related to the diseases status and may be used as a potential diagnostic or biomarker in canine mammary gland tumors.

Does TLS Exist in Canine Mammary Gland Tumours? Preliminary Results in Simple Carcinomas

Neoplastic progression is influenced by the expression of tumour antigens that activate an anti-tumour immune response. Human medical studies show that this body defence is carried out in secondary lymphoid organs (SLOs) but also directly in the tumour through organized cellular aggregates that are called tertiary lymphoid structures (TLSs). However, their occurrence has different meanings in different tumour types. For example, the presence of TLSs in breast cancer is associated with the most aggressive subtypes. This paper aimed to study TLSs in canine mammary simple carcinomas. A morphological assessment of the inflammatory infiltrate was performed on H&E sections of fifty cases. Immunohistochemistry was then carried out to typify the inflammatory cells in the tumour microenvironment. Results showed that, sometimes, inflammatory infiltrates were organized in follicles close to high-grade carcinomas, simulating a lymphoid organization, as in breast cancer. Therefore, we can assume that even in canine mammary tumours, TLSs exist and they are entities to consider due to their presence in the most aggressive histotypes or tumours with a high degree of malignancy.

The Analysis of E-Cadherin, N-Cadherin, Vimentin, HER-2, CEA, CA15-3 and SF Expression in the Diagnosis of Canine Mammary Tumors

Canine mammary tumors (CMTs) are one of the most common tumors in female dogs, and they are associated with a poor prognosis owing to their high rate of recurrence and metastasis rates, which make their diagnosis especially important in clinical veterinary medicine. In this study, the characteristics of tumors were observed in dogs suffering from CMTs, and clinical diagnosis and histopathology were used to identify tumors. Furthermore, the expression levels of tumor markers for CMTs were analyzed by enzyme-linked immunosorbent assay (ELISA) and quantitative PCR (qPCR). Upon clinical examination, dogs with CMTs displayed a distinct and irregular mass in the mammary gland, and X-ray (Latero-lateral and ventro-dorsal views) and ultrasonography of the abdomen revealed a moderately echogenic mass at the mammary gland with slightly stronger density than the surrounding tissue. A total of 30 tumors were identified by histopathology, 11 benign and 19 malignant. Changes in some indicators in dogs suffering from CMTs and healthy dogs suggested that there were multiple direct or paraneoplastic changes associated with tumors that could be detected/suspected by hematological examination, and ELISA revealed the HER-2 serum concentrations were significantly different between healthy animals and those with malignant tumors. qPCR indicated that tumor markers N-cadherin, Vimentin, HER-2, CEA, CA15-3 and SF were higher in dogs with malignant tumors than healthy dogs, with a low level of E-cadherin in malignant tumors. This study verified that serological tests and molecular biological tests were essential to the early diagnosis, treatment and prognosis of dogs with tumors.

A living biobank of canine mammary tumor organoids as a comparative model for human breast cancer

Mammary tumors in dogs hold great potential as naturally occurring breast cancer models in translational oncology, as they share the same environmental risk factors, key histological features, hormone receptor expression patterns, prognostic factors, and genetic characteristics as their human counterparts. We aimed to develop in vitro tools that allow functional analysis of canine mammary tumors (CMT), as we have a poor understanding of the underlying biology that drives the growth of these heterogeneous tumors. We established the long-term culture of 24 organoid lines from 16 dogs, including organoids derived from normal mammary epithelium or benign lesions. CMT organoids recapitulated key morphological and immunohistological features of the primary tissue from which they were derived, including hormone receptor status. Furthermore, genetic characteristics (driver gene mutations, DNA copy number variations, and single-nucleotide variants) were conserved within tumor-organoid pairs. We show how CMT organoids are a suitable model for in vitro drug assays and can be used to investigate whether specific mutations predict therapy outcomes. Specifically, certain CMT subtypes, such as PIK3CA mutated, estrogen receptor-positive simple carcinomas, can be valuable in setting up a preclinical model highly relevant to human breast cancer research. In addition, we could genetically modify the CMT organoids and use them to perform pooled CRISPR/Cas9 screening, where library representation was accurately maintained. In summary, we present a robust 3D in vitro preclinical model that can be used in translational research, where organoids from normal, benign as well as malignant mammary tissues can be propagated from the same animal to study tumorigenesis.

HER2 Overexpression and Cytogenetical Patterns in Canine Mammary Carcinomas

Human epidermal growth factor receptor 2 (HER2) is a tyrosine kinase receptor that promotes tumor cell growth and is implicated in the pathogenesis of human breast cancer. The role of HER2 in canine mammary carcinomas (CMCs) is not clear. Therefore, this study aimed to examine the protein expression and cytogenetic changes of HER2 and their correlation with other clinical–pathological parameters in CMC. We retrospectively selected 112 CMCs. HER2, ER, and Ki67 were assessed by immunohistochemistry. HER2 antibody validation was investigated by immunoblot on mammary tumor cell lines. Fluorescence in situ hybridization (FISH) was performed with probes for HER2 and CRYBA1 (control gene present on CFA9). HER2 protein overexpression was detected in 15 carcinomas (13.5%). A total of 90 carcinomas were considered technically adequate by FISH, and 8 out of 90 CMC (10%) were HER2 amplified, 3 of which showed a cluster-type pattern. HER2 overexpression was correlated with an increased number of HER2 gene copies (p = 0.01; R = 0.24) and overall survival (p = 0.03), but no correlation with ER, Ki67, grade, metastases, and tumor-specific survival was found. Surprisingly, co-amplification or polysomy was identified in three tumors, characterized by an increased copy number of both HER2 and CRYBA1. A morphological translocation-fusion pattern was recognized in 20 carcinomas (22%), with a co-localized signal of HER2 and CRYBA1. HER2 is not associated with clinical–pathological parameters of increased malignancy in canine mammary tumors, but it is suitable for studying different amplification patterns.

RT-qPCR Expression Profiles of Selected Oncogenic and Oncosuppressor miRNAs in Formalin-Fixed, Paraffin-Embedded Canine Mammary Tumors

MicroRNAs (miRNAs) can act as oncogenes or oncosuppressor genes, and their involvement in nearly all cancer-associated processes makes these small molecules promising diagnostic and prognostic biomarkers in cancer, as well as specific targets for cancer therapy. This study aimed to investigate the expression of 7 miRNAs (miR-18a, miR-18b, miR-22, miR-124, miR-145, miR-21, miR-146b) in formalin-fixed, paraffin-embedded canine mammary tumors (CMTs) by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Twenty-six mammary samples were selected, including 22 CMTs (7 benign; 15 malignant) and 4 control samples (3 normal mammary gland and 1 case of lobular hyperplasia). Oncogenic miR-18a, miR-18b and miR-21 were significantly upregulated in malignant tumors compared with control tissues (p < 0.05). Conversely, oncosuppressor miR-146b was significantly downregulated in benign and malignant mammary tumors compared with control samples (p < 0.05) while, no group-related differences in the expression levels of miR-22, miR-124 and miR-145 were found (p > 0.05). Upregulated miRNAs found here, may regulate genes involved in receptor-mediated carcinogenesis and proteoglycan remodeling in cancer; while miRNA with reduced expression can regulate genes involved in Toll-like receptor and MAPK signaling pathways. According to the results obtained in the current study, the oncogenic and oncosuppressor miRNAs analyzed here are dysregulated in CMTs and the dysregulation of miRNA targets may lead to specific altered cellular processes and key pathways involved in carcinogenesis. Of note, since oncogenic miRNAs predicted to regulate neoplastic cell proliferation and hormonal activities, they may play an active role in neoplastic transformation and/or progression, having mechanistic and prognostic relevance in CMTs.

Strain and Shear-Wave Elastography and Their Relationship to Histopathological Features of Canine Mammary Nodular Lesions

Mammary gland tumours have a significant impact on the health of dogs, requiring diagnostic tools to support clinicians to develop appropriate therapeutic strategies. Sonoelastography is an emerging technology that is able to define the stiffness of the tissue and has promising applications in the evaluation of mammary gland lesions. In the present study, strain elastography (STE) and shear-wave (SWE) elastography were compared in 38 mammary nodular lesions for their ability to define the histopathological features of canine mammary lesions. Among the techniques, SWE showed better repeatability (intraclass correlation coefficient: 0.876), whereas STE was found to be only acceptable (intraclass correlation coefficient: 0.456). Mammary nodular lesions showed a wide range of tissue stiffening with a similar mean value for STE and SWE in benign (4 ± 0.3 and 115.4 ± 12.6 kPa, respectively) and malignant lesions (3.8 ± 0.1 and 115.5 ± 4.5 kPa, respectively). A significant correlation was found between lesion fibrosis and STE (STE-I: r = 0.513, p < 0.001; STE-R: r = 0.591, p < 0.001) or SWE-S (r = 0.769; p < 0.001). In conclusion, SWE was reliable and correlated with fibrosis and was similar for both benign and malignant lesions, suggesting that other collateral diagnostic techniques should be considered in conjunction with SWE to characterize mammary nodular lesions in dogs.

Rapid Evaporative Ionization Mass Spectrometry-Based Lipidomics for Identification of Canine Mammary Pathology

The present work proposes the use of a fast analytical platform for the mass spectrometric (MS) profiling of canine mammary tissues in their native form for the building of a predictive statistical model. The latter could be used as a novel diagnostic tool for the real-time identification of different cellular alterations in order to improve tissue resection during veterinary surgery, as previously validated in human oncology. Specifically, Rapid Evaporative Ionization Mass Spectrometry (REIMS) coupled with surgical electrocautery (intelligent knife—iKnife) was used to collect MS data from histologically processed mammary samples, classified into healthy, hyperplastic/dysplastic, mastitis and tumors. Differences in the lipid composition enabled tissue discrimination with an accuracy greater than 90%. The recognition capability of REIMS was tested on unknown mammary samples, and all of them were correctly identified with a correctness score of 98–100%. Triglyceride identification was increased in healthy mammary tissues, while the abundance of phospholipids was observed in altered tissues, reflecting morpho-functional changes in cell membranes, and oxidized species were also tentatively identified as discriminant features. The obtained lipidomic profiles represented unique fingerprints of the samples, suggesting that the iKnife technique is capable of differentiating mammary tissues following chemical changes in cellular metabolism.

COX-2 expression in mammary invasive micropapillary carcinoma is associated with prognostic factors and acts as a potential therapeutic target in comparative oncology

Pure human and canine mammary invasive micropapillary carcinoma is a rare malignant epithelial tumor accounting for 0.9 to 2% of all invasive mammary carcinomas and present a high rate of lymphatic invasion and metastasis, with unfavorable prognosis. Surgery and chemotherapy are standard treatments for almost all mammary cancer in both species, as well as hormonal and target therapies available for human patients. However, depending on the patient's clinical staging, satisfactory therapeutic results for invasive micropapillary carcinoma are a challenge due to its high capacity of invasion and metastasis. Cyclooxygenase-2 (COX-2) isoform is an important enzyme stimulated by cytokines, growth factors and oncogenes activation to synthetizes prostaglandins in inflammatory process. COX-2 overexpression is associated with angiogenesis and invasion and contributes to cancer development, disease progression, tumor recurrence and regional lymph node metastasis in human and canine mammary carcinomas. This enzyme can be targeted by non-steroidal anti-inflammatory drugs and its inhibition can reduce tumor growth and metastasis in several cancer types. Given the similarity between both species, the present study aims to elucidate the involvement of COX-2 mRNA and protein expression in canine (cIMPC) and human (hIMPC) pure invasive mammary micropapillary carcinoma, with clinicopathological and survival data. Twenty-nine cases of cIMPC and 17 cases of hIMPC were analyzed regarding histologic type, grade, age, tumor size, lymph node condition, extracapsular extension, inflammatory infiltrate and immunophenotype. When available, information on adjuvant treatment, recurrence, metastasis and overall survival were collected. The present study demonstrated COX-2 protein expression in 65.5% of cIMPC and 92.3% of hIMPC, and an association with more advanced histological grades in bitches and higher Ki67 in women. COX-2 mRNA expression was significantly higher in cIMPC than in hIMPC, and its expression was not associated with COX-2 protein expression in both species. COX-2 mRNA expression was associated with negative-ER hIMPC as well as higher Ki67. cIMPC demonstrated proportional early development, more regional metastasis, and a prevalence of negative estrogen receptor, than hIMPC. This is the first time COX-2 expression is associated with negative prognostic factors in both cIMPC and hIMPC, besides the overexpression of COX-2 protein in such unfavorable histological type, which suggests that COX-2 can act as a potential target in IMPC.

Sentinel Lymph Node Biopsy Is Feasible in Dogs with Scars from Prior Local Excision of Solid Malignancies

Simple Summary

Sentinel lymph node (SLN) excision is gaining relevance in the management of various canine malignancies due to its recognized impact on staging and treatment choices. However, the technologies to perform SLN mapping are only available to a few referral centers, and there is increasing demand for secondary nodal staging after prior tumor excision at the primary care institution. This retrospective study investigated the feasibility and usefulness of SLN biopsy in dogs with surgical scars resulting from the removal of various solid tumors referred for further staging and/or adjuvant treatment options. Thirty-three dogs with 34 scars underwent SLN biopsy at a median of 50 days after primary tumor excision. An SLN was identified for 31/34 scars, translating to a detection rate of 91.2%. Metastases were identified with histopathology in 13/31 dogs (41.9%) and they all had an excision of a mast cell tumor. SLN biopsy should be suggested in dogs presenting with scars from prior solid tumor excision, considering the observed detection rate and the importance of knowing the metastatic status of the SLN in oncological diseases.

Abstract

Sentinel lymph node (SLN) biopsy is a well-established staging tool in canine oncology. This study aims to explore the feasibility of SLN biopsy in dogs with scars from prior excised solid malignancies that were referred for further tumor staging and/or adjuvant treatment options. Mapping was either performed using radiopharmaceutical, methylene blue, and/or near-infrared fluorescent (NIRF) imaging. Thirty-three dogs with 34 scars from prior excision of the mast cell tumor (MCT) (n = 29), soft tissue sarcoma (n = 2), oral melanoma (n = 1), subungual melanoma (n = 1), and mammary adenocarcinoma (n = 1) were retrospectively enrolled. Primary treatment consisted of curative intent/wide tumor excisions in 50.0% of dogs and marginal excision in the remaining 50.0%. The median time between tumor excision and SLN biopsy was 50 days (range 17–110 days). The procedure was successful in 31/34 scars, translating to a detection rate of 91.2%. The SLN did not correspond to the regional lymph node in 19/31 scars (61.3%). SLN metastases were histologically identified in 13/31 (41.9%) dogs, all of them affected by MCT. Based on our results, SLN biopsy using lymphoscintigraphy/methylene blue and/or NIRF is feasible in dogs presenting with scars from the prior surgical excision of solid tumors, and should be suggested for accurate nodal staging.

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.

Reproducibility and Feasibility of Classification and National Guidelines for Histological Diagnosis of Canine Mammary Gland Tumours: A Multi-Institutional Ring Study

Simple Summary

Tumours of the mammary gland are common in humans, as in canine species. They are very heterogenous with numerous morphological variants and different biologic behaviours. In the last few decades, several efforts have been made to classify these tumours histologically and establish the level of malignancy by using histologic grading systems. However, reproducibility and diagnostic agreement of such classification and grading have been only rarely assessed. In this study, we tested the variability in diagnoses performed by 15 pathologists using the same classification and grading system. Prior to the study, pathologists agreed on guidelines regarding how to apply these systems. Pathologists worked blindly on 36 digital histologic slides of canine mammary tumours. The agreement was statistically analysed using Cohen’s kappa coefficient that, when equal to 1, indicates perfect agreement. The overall agreement in the identification of hyperplastic-dysplastic/benign/malignant lesions was substantial (kappa 0.76), while outcomes on morphological classification had only a moderate agreement (k = 0.54). Tumour grade assigned by pathologists was the least concordant and kappa could not be calculated. Although promising, the results underline that each diagnostic/grading system should be assessed and optimized for standardization and high diagnostic agreement.

Abstract

Histological diagnosis of Canine Mammary Tumours (CMTs) provides the basis for proper treatment and follow-up. Nowadays, its accuracy is poorly understood and variable interpretation of histological criteria leads to a lack of standardisation and impossibility to compare studies. This study aimed to quantify the reproducibility of histological diagnosis and grading in CMTs. A blinded ring test on 36 CMTs was performed by 15 veterinary pathologists with different levels of education, after discussion of critical points on the Davis-Thompson Foundation Classification and providing consensus guidelines. Kappa statistics were used to compare the interobserver variability. The overall concordance rate of diagnostic interpretations of WP on identification of hyperplasia-dysplasia/benign/malignant lesions showed a substantial agreement (average k ranging from 0.66 to 0.82, with a k-combined of 0.76). Instead, outcomes on ICD-O-3.2 morphological code /diagnosis of histotype had only a moderate agreement (average k ranging from 0.44 and 0.64, with a k-combined of 0.54). The results demonstrated that standardised classification and consensus guidelines can produce moderate to substantial agreement; however, further efforts are needed to increase this agreement in distinguishing benign versus malignant lesions and in histological grading.

Association of mast cell density, microvascular density and endothelial area with clinicopathological parameters and prognosis in canine mammary gland carcinomas

Background

Mast cell density has been shown to have both enhancing and inhibiting effects on tumour progression and the ability to predict breast cancer behaviour in humans. However, prognostic results have been contradictory. Some previous studies suggested involvement of mast cells in the progression of canine mammary tumours. This study investigated total, intratumoural and peritumoural mast cell densities by Giemsa staining, and their association with clinicopathological parameters and the disease outcome of canine mammary tumours. In addition, since mast cells promote angiogenesis, the microvascular density and endothelial area were evaluated by CD31 immunostaining.

Results

Intratumoural mast cell density was associated with tumour size, lymph node involvement and tumour-infiltrating lymphocyte count, while peritumoural mast cell density was associated with grade. The endothelial area was associated with grade, mitotic index, tubular formation and proliferation index. Tumours with a high grade, high total intratumoural mast cell density and a larger endothelial area were associated with shorter disease-free survival. Intratumoural mast cell density and grade were found to be independent prognostic factors.

Conclusions

These results suggest that intratumoural mast cell density and the endothelial area can be used to evaluate the aggressiveness of canine mammary carcinomas, while intratumoural mast cell density could be of use as an independent predictor of a prognosis of disease-free survival. Peritumoural mast cell density does not seem to influence tumour behaviour.

Canine and feline in situ mammary carcinoma: A comparative review

Carcinoma in situ of the breast is a well-known entity in humans. In veterinary medicine, particularly in canine and feline mammary literature, there is no agreement whether the term in situ should be used to indicate a specific carcinoma histotype or the noninvasive status of a carcinoma of any histotype. Moreover, in the most recent histologic classification of mammary tumors published by the Davis-Thompson Foundation, it is suggested to abandon the term carcinoma in situ given the lack of standardized criteria defining this entity, replacing it with epitheliosis or ductal/lobular hyperplasia with severe atypia. This publication presents a critical review of the term in situ in human and veterinary medicine considering the evolution of the term over the years and its heterogeneous use by different authors, including variations in immunohistochemical markers for classification. This review aims to point out the lack of uniformity in the nomenclature and classification issues in veterinary medicine regarding the use of the term in situ, laying the ground for a process of standardization in future publications.

Epidemiological Investigation of Canine Mammary Tumors in Mainland China Between 2017 and 2021

Epidemiological studies enable us to analyze disease behavior, define risk factors, and establish fundamental prognostic criteria. This study aimed to determine the epidemiological and clinical characteristics of canine tumors diagnosed during the years 2017–2021. The results showed that canine mammary tumors were the most common tumors, and their relative incidence for 5-years-total was 46.71% (504/1,079), with 48.41% (244/504) of benign, and 51.59% (260/504) of malignant. Pure breeds accounted for 84.13% (424/504) of submissions, and adult female dogs (9–12 years old) were most frequently involved, followed by 5–8-year-old females. Remarkably, 2.58% (13/504) occurred in the male dogs. In addition, a high prevalence of mammary tumors (77.38%, 390/504) was diagnosed in unneutered dogs, and different incidence rates were observed in different regions (Northeast, Southeast, Northwest and Southwest China). For clinical factors, the tumor size ranged from 0.5 to 28 cm, with the 0–5 cm being the most common tumor size (47.82%, 241/504), and malignant tumors (4.33 ± 2.88 cm, mean ± SD) were bigger than benign ones (3.06 ± 1.67 cm, mean ± SD) (p &lt; 0.001). The incidence of single tumor (55.36%, 279/504) was higher than that of multiple tumors in dogs, while the latter had a higher incidence of malignant tumors (74.67%, 168/225). According to this study, we also found that canine mammary tumors were more common in the last two pairs of mammary glands. In addition, multiple linear regression analysis showed that there was linear significant relationship between three independent variables (age, tumor size, and tumor number) and histological properties of canine mammary tumor [(p&gt;|t|) &lt; 0.05]. This is the first retrospective statistical analysis of such a large dataset in China to reveal the link between epidemiological clinical risks and histological diagnosis. It aids in the improvement of the host's knowledge of canine tumor disorders and the early prevention of canine mammary tumors.

Validation of AmpliSeq NGS Panel for BRCA1 and BRCA2 Variant Detection in Canine Formalin-Fixed Paraffin-Embedded Mammary Tumors

Mammary carcinomas are the most common neoplasms observed in women and in female dogs. Canine mammary tumors show epidemiological, clinical, genetic, and prognostic characteristics comparable to human breast cancers. The recent introduction of next generation sequencing (NGS) technologies has greatly improved research and diagnostics for humans, while these new tools still need to be implemented in animal models. In this study we developed and validated an AmpliSeq Panel assay for the identification of BRCA variants in twenty-two different dogs. The amplicon mean coverage was 5499× and uniformity was higher than 98% in all samples. The results of germline single nucleotide variants (SNVs) and insertions/deletions (INDELs) were fully concordant regardless of the types of samples considered (blood, fresh and FFPE tissues). Moreover, despite the high DNA degradation observed in older FFPE blocks (>5 years), the assay allowed full coverage of all amplicons for downstream analyses. We consider the NGS panel developed in this study as a useful tool for expanding information on BRCA genes in the veterinary field and for human health from a comparative oncology perspective.

Grading Systems for Canine Urothelial Carcinoma of the Bladder: A Comparative Overview

Simple Summary

Tumor histological grading systems are a tool widely used by human pathologists in oncology to support the assessment of tumor behavior and patient prognosis by clinical oncologists. In veterinary medicine, several tumor types already have a histological grading system used for these purposes, but some of these schemes lack reproducibility or correlation with clinical parameters, such as the correlation of the grade with survival time. This is the case for the grading systems proposed for canine bladder urothelial carcinoma. Over the years, some grading systems have been described for this type of tumor in dogs but without any routine use by pathologists and, consequently, without any application in clinical practice either. Based on this fact, the present study aimed to review the histological grading systems that exist in both human and veterinary medicine for bladder urothelial carcinoma, carrying out a critical analysis of their differences and thereby encouraging their real practical use and application in a relevant number of cases, prospectively. In this way, a histological grading system could be chosen or built from the existing ones and the knowledge about the behavior of this neoplasm in canine species could be improved, helping clinicians to establish a prognosis and personalized treatment for each patient with bladder urothelial carcinoma and also consider the predictive markers associated with treatment outcomes.

Abstract

The relationship between tumor morphology and clinical behavior is a key point in oncology. In this scenario, pathologists and clinicians play a pivotal role in the identification and testing of reliable grading systems based on standardized parameters to predict patient prognosis. Dogs with bladder urothelial carcinoma (BUC) were recently proposed as a “large animal” model for the study of human BUCs due to the similar morphology and metastasis locations. BUC grading systems are consolidated in human medicine, while in veterinary medicine, the BUC grading systems that have been proposed for canine tumors are not yet applied in routine diagnostics. These latter systems have been proposed, decade by decade, over the last thirty years, and the reason for their scarce application is mainly related to a lack of specific cutoff values and studies assessing their prognostic relevance. However, for any prognostic study, reliable grading is necessary. The aim of the present article was to give an overview of the BUC grading systems available in both human and veterinary pathology and provide an extensive description and a critical evaluation to support veterinary researchers in the choice of possible grading systems to apply in future studies on canine BUCs.

Utility of Serum Ki-67 as a Marker for Malignancy in Dogs

Simple Summary

Although serum tumour markers offer an uncomplicated, non-invasive examination method and possible therapeutic options, they are still rarely used in veterinary medicine. Our marker of interest, the Ki-67 protein, can only be detected in the active phases of the cell cycle. Therefore, it is a suitable marker for assessing the proliferating cell fraction of an organism and can thus provide information about potentially present, rapid-growing tumour tissue. The purpose of our study was to determine whether Ki-67 could be considered as a possible tumour marker in canine serum for veterinary medicine. We measured serum concentrations of Ki-67 in dogs with various malignant tumours, such as carcinomas, sarcomas, and lymphomas. In the dogs with malignant tumours we determined significantly higher serum Ki-67 concentrations compared with healthy dogs and dogs with non-malignant diseases. No significant difference in serum Ki-67 concentration was observed between the different types of cancer or between benign and malignant mammary tumours. Our investigations also included some inflammatory parameters measured in blood, such as neutrophils, lymphocytes, and monocytes, with mixed results. The results of our study suggest that Ki-67 may be useful as a potential serum tumour marker, providing information about the presence of malignant diseases in a dog.

Abstract

Tumour markers are scarcely used in veterinary medicine, although they are non-invasive, contribute to a faster diagnosis and new therapeutic options. The nuclear protein Ki-67 is absent in G₀-phase but is detectable throughout all active phases of the cell cycle. Consequently, it is used as a marker for the proliferating cell fraction of a cell population and thus could indicate neoplastic tissue present. Our study is designed to show whether Ki-67 can be considered as a potential canine serum tumour marker for veterinary medicine. We measured serum concentrations of Ki-67 in dogs with various malignant tumours (carcinomas (n = 35); sarcomas (n = 26); lymphomas (n = 21)) using a commercially available quantitative sandwich ELISA from mybiosource. Dogs with malignant tumours showed significantly higher serum Ki-67 concentrations compared to healthy dogs (n = 19) and non-neoplastic diseased dogs (n = 26). No significant difference in serum Ki-67 concentration was detected between carcinoma, sarcoma, and lymphoma, nor between mammary adenocarcinoma and adenoma. In our investigations we also included some inflammatory parameters measured in blood, such as neutrophils, lymphocytes, and monocytes, and gained mixed results. The results of our study suggest that Ki-67 may be useful as a potential serum tumour marker, providing information about the presence of malignancies in a dog.