Canine prostate carcinomas express markers of urothelial and prostatic differentiation

Effective detection of BRAFV595E mutation in canine urothelial and prostate carcinomas using immunohistochemistry

Canine urothelial carcinoma (UC) and prostate carcinoma (PC) frequently exhibit the BRAFV595E mutation, akin to the BRAFV600E mutation common in various human cancers. Since the initial discovery of the BRAF mutation in canine cancers in 2015, PCR has been the standard method for its detection in both liquid and tissue biopsies. Considering the similarity between the canine BRAFV595E and human BRAFV600E mutations, we hypothesized that immunohistochemistry (IHC) using a BRAFV600E-specific antibody could effectively identify the canine mutant BRAFV595E protein. We tested 122 canine UC (bladder n = 108, urethra n = 14), 21 PC, and benign tissue using IHC and performed digital droplet PCR (ddPCR) on all 122 UC and on 14 IHC positive PC cases. The results from ddPCR and IHC were concordant in 99% (135/136) of the tumours. Using IHC, BRAFV595E was detected in 72/122 (59%) UC and 14/21 (65%) PC. Staining of all benign bladder and prostate tissues was negative. If present, mutant BRAF staining was homogenous, with rare intratumour heterogeneity in three (4%) cases of UC. Additionally, the BRAFV595E mutation was more prevalent in tumours with urothelial morphology, and less common in glandular PC or UC with divergent differentiation. This study establishes that BRAFV600-specific IHC is a reliable and accurate method for detecting the mutant BRAFV595E protein in canine UC and PC. Moreover, the use of IHC, especially with tissue microarrays, provides a cost-efficient test for large-scale screening of canine cancers for the presence of BRAF mutations. This advancement paves the way for further research to define the prognostic and predictive role of this tumour marker in dogs and use IHC to stratify dogs for the treatment with BRAF inhibitors.

Canine Prostate Cancer: Current Treatments and the Role of Interventional Oncology

Prostate carcinoma is one of the most common cancers worldwide in men, with over 3 million men currently living with prostate carcinoma. In men, routine screening and successful treatment schemes, including radiation, prostatectomy, or hormone therapy, have allowed for high survivability. Dogs are recognized as one of the only mammals to spontaneously develop prostate neoplasia and are an important translational model. Within veterinary medicine, treatment options have historically been limited in efficacy or paired with high morbidity. Recently, less invasive treatment modalities have been investigated in dogs and people and demonstrated promise. Below, current treatment options available in dogs and people are reviewed, as well as a discussion of current and future trends within interventional treatment for canine PC.

Tissue S100/calgranulin expression and blood neutrophil-to-lymphocyte ratio (NLR) in prostatic disorders in dogs

BACKGROUND

Prostatic carcinoma (PCA) is a rare but severe condition in dogs that is similar to the androgen-independent form of PCA in men. In contrast to humans, PCA is difficult to diagnose in dogs as reliable biomarkers, available for PCA screening in human medicine, are currently lacking in small animal oncology. Calprotectin (S100A8/A9) and S100A12 are Ca2+-binding proteins of the innate immune system with promising potential to distinguish malignant from benign urogenital tract conditions, similar to the blood neutrophil-to-lymphocyte-ratio (NLR). However, both have not yet been extensively investigated in dogs with PCA. Thus, this study aimed to evaluate the expression of the S100/calgranulins (calprotectin, S100A12, and their ratio [Cal-ratio]) in prostatic biopsies from nine dogs with PCA and compare them to those in dogs with benign prostatic lesions (eight dogs with prostatitis and ten dogs with benign prostatic hyperplasia [BPH]) as well as five healthy controls. In addition, blood NLRs were investigated in twelve dogs with PCA and 22 dogs with benign prostatic conditions.

RESULTS

Tissue S100A8/A9+ cell counts did not differ significantly between tissue from PCA and prostatitis cases (P = 0.0659) but were significantly higher in dogs with prostatitis than BPH (P = 0.0013) or controls (P = 0.0033). S100A12+ cell counts were significantly lower in PCA tissues than in prostatitis tissue (P = 0.0458) but did not differ compared to BPH tissue (P = 0.6499) or tissue from controls (P = 0.0622). Cal-ratios did not differ significantly among the groups but were highest in prostatitis tissues and significantly higher in those dogs with poor prostatitis outcomes than in patients that were still alive at the end of the study (P = 0.0455). Blood NLR strongly correlated with prostatic tissue S100A8/A9+ cell counts in dogs with PCA (ρ = 0.81, P = 0.0499) but did not differ among the disease groups of dogs.

CONCLUSIONS

This study suggests that the S100/calgranulins play a role in malignant (PCA) and benign (prostatic inflammation) prostatic conditions and supports previous results in lower urinary tract conditions in dogs. These molecules might be linked to the inflammatory environment with potential effects on the inflammasome. The blood NLR does not appear to aid in distinguishing prostatic conditions in dogs. Further investigation of the S100/calgranulin pathways and their role in modulation of tumor development, progression, and metastasis in PCA is warranted.

A Retrospective Clinico-Pathologic Study of 35 Dogs with Urethral Transitional Cell Carcinoma Undergoing Treatment

Chemotherapy and cyclooxygenase inhibitors (COXi) are primary treatments for canine urethral transitional cell carcinoma (uTCC), a tumor known for its aggressiveness and poor prognosis. This retrospective study aimed to evaluate the clinico-pathological characteristics, treatment modalities, and prognostic factors of 35 dogs with confirmed uTCC that received chemotherapy and COXi. Upon admission, urethral obstruction (UO) and urinary tract infection (UTI) were observed in seven (20%) dogs each. Gemcitabine (n = 20; 57.1%) and vinblastine (n = 10; 28.6%) were commonly used as first-line therapies, with four dogs also receiving radiation therapy. Based on RECIST, one (2.9%) dog achieved complete remission, nine (25.7%) partial remission, 20 (57.14%) showed stable disease, and five (14.3%) progressed. Among dogs with UO, six (85.7%) showed resolution or improvement after the first chemotherapy dose. The median time to local progression was 171 days (range: 107-235), and the median survival time was 333 days (range: 158-508). Dogs with UO upon admission had a higher risk of local progression, while both UO and UTI were associated with an increased risk of overall disease progression and tumor-related death. Additionally, gemcitabine significantly improved metastatic control. This study identified UO and UTI as negative prognostic factors, highlighting the importance of a multimodal approach in managing uTCC.

Establishment of a BRAF V595E-mutant canine prostate cancer cell line and the antitumor effects of MEK inhibitors against canine prostate cancer

Canine prostate cancer (cPCa) is a malignant neoplasm with no effective therapy. The BRAF V595E mutation, corresponding to the human BRAF V600E mutation, is found frequently in cPCa. Activating BRAF mutations are recognized as oncogenic drivers, and blockade of MAPK/ERK phosphorylation may be an effective therapeutic target against BRAF-mutated tumours. The aim of this study was to establish a novel cPCa cell line and to clarify the antitumor effects of MEK inhibitors on cPCa in vitro and in vivo. We established the novel CHP-2 cPCa cell line that was derived from the prostatic tissue of a cPCa patient. Sequencing of the canine BRAF gene in two cPCa cell lines revealed the presence of the BRAF V595E mutation. MEK inhibitors (trametinib, cobimetinib and mirdametinib) strongly suppressed cell proliferation in vitro, and trametinib showed the highest efficacy against cPCa cells with minimal cytotoxicity to non-cancer COPK cells. Furthermore, we orally administered 0.3 or 1.0 mg/kg trametinib to CHP-2 xenografted mice and examined its antitumor effects in vivo. Trametinib reduced tumour volume, decreased phosphorylated ERK levels, and lowered Ki-67 expression in xenografts in a dose-dependent manner. Although no clear adverse events were observed with administration, trametinib-treated xenografts showed osteogenesis that was independent of dosage. Our results indicate that trametinib induces cell cycle arrest by inhibiting ERK activation, resulting in cPCa tumour regression in a dose-dependent manner. MEK inhibitors, in addition to BRAF inhibitors, may be a targeted agent option for cPCa with the BRAF V595E mutation.

A Review on Canine and Feline Prostate Pathology

Prostatic diseases are very common in male dogs, accounting for 3–10% of cases submitted to the veterinary practitioners. Commonly reported canine prostatic disorders include prostatic hyperplasia, prostatitis, prostatic cysts and prostatic carcinoma. However, clinical signs may be non-specific, or many cases are asymptomatic, thus leading to a difficult estimation of the actual prevalence of clinical cases. On the other side, because of the rare occurrence of prostate disease in cats, very little is known about pathogenesis, diagnostic approaches and treatment. The goal of this review is to provide detailed clinical and pathological overview of the feline and canine prostatic pathology, including the most up-to-date classification systems and histological findings. Emphasis is places on gross, cytological and histological features that are critical to reach a definitive diagnosis for a proper treatment and prognosis.

An RNA-Seq-Based Framework for Characterizing Canine Prostate Cancer and Prioritizing Clinically Relevant Biomarker Candidate Genes

Prostate cancer (PCa) in dogs is a highly malignant disease akin to its human counterpart. In contrast to the situation in humans, multi-gene approaches facilitating risk stratification of canine PCa are barely established. The aims of this study were the characterization of the transcriptional landscape of canine PCa and the identification of diagnostic, prognostic and/or therapeutic biomarkers through a multi-step screening approach. RNA-Sequencing of ten malignant tissues and fine-needle aspirations (FNA), and 14 nonmalignant tissues and FNAs was performed to find differentially expressed genes (DEGs) and deregulated pathways. The 4098 observed DEGs were involved in 49 pathways. These 49 pathways could be grouped into five superpathways summarizing the hallmarks of canine PCa: (i) inflammatory response and cytokines; (ii) regulation of the immune system and cell death; (iii) cell surface and PI3K signaling; (iv) cell cycle; and (v) phagosome and autophagy. Among the highly deregulated, moderately to strongly expressed DEGs that were members of one or more superpathways, 169 DEGs were listed in relevant databases and/or the literature and included members of the PCa pathway, oncogenes, prostate-specific genes, and druggable genes. These genes are novel and promising candidate diagnostic, prognostic and/or therapeutic canine PCa biomarkers.

Histological and immunohistochemical investigation of canine prostate carcinoma with identification of common intraductal carcinoma component

A limited number of species, including men and dogs, spontaneously develop prostate cancer (PC). The histological and molecular relevance of canine PC as a model for the disease in men remains controversial. To address this challenge, this study aimed to assess the histomorphology and expression of basal cell, urothelial and neuroendocrine markers [p63, high molecular weight cytokeratin (HMWCK), Uroplakin 3 (UPIII), neuron‐specific enolase (NSE)] in canine PC (n = 41). Based on histomorphology, 10/41 (24%), 21/41 (51%) and 9/41 (22%) were classified as adenocarcinoma (AC), urothelial carcinoma (UC), and mixed carcinoma, respectively. Tumour inflammation was common, frequently severe [20/41 (49%)], and associated with neutering (p < .02) and urothelial differentiation (p < .02). Most (36/40, 90%) cancers contained only rare cells with basal cell marker expression or were negative. The expression of UPIII was absent or weak in the majority (33/38, 87%) of tumours, with moderate to strong staining in the remaining cases. NSE expression in PC was rare and limited to 2/14 (14%) cases. Tumour extension into benign ducts and glands was a common finding with presence in 17/39 (44%) of carcinomas with and without urothelial differentiation. In conclusion, we confirm that canine PC is characterized by absent or weak expression of basal cell and urothelial markers. Although rare, NSE expression, potentially indicating neuroendocrine differentiation, is reported for the first time in canine PCa. Intraductal carcinoma of the prostate with concurrent invasive PCa (IDCP‐inv) is a frequent, not previously described, finding in dogs with PC.

Effects of the Latex of Synadenium grantii Hook F. (Euphorbiaceae) on a Preclinical Model of Canine Prostate Cancer

Prostatic cancer (PC) stands out in terms of its occurrence, pathophysiology, and unfavorable prognostics in humans and dogs. Natural drugs bear an integrative potential for conventional antineoplastic treatments. In this context, the bioproducts of Synadenium grantii have been empirically used in different parts of Brazil for the integrative treatment of prostate cancer in humans. However, there is no availability of scientific evidence of the antitumor effects of S. grantii. Therefore, this study aimed to investigate the bioactive compounds in the latex of S. grantii using the high-resolution mass spectrophotometry (HRMS) and to evaluate its cytotoxic effects on primary canine PC cell cultures. Four fragments of phorbol ester were identified as potential bioactive compounds using the HRMS. With the help of an MTT ([3-(4,5-dimethyldiazol-2-yl)-2,5 diphenyltetrazolium bromide]) assay, two canine prostatic carcinoma cell lines (PC 1 and PC2) showed a decrease in the tumor cell count, with an Inhibitory concentration 50 (IC50)of 0.8469 and 0.6068 mg/ml, respectively, for PC1 and PC2. In conclusion, the latex of S. grantii contains phorbol esters in its composition, and its aqueous solution has a cytotoxic effect on canine metastatic PC cells in vitro.

A Comparative Meta-Analysis and in silico Analysis of Differentially Expressed Genes and Proteins in Canine and Human Bladder Cancer

Canine and human bladder cancer present similar anatomical, morphological, and molecular characteristics, and dogs can be considered a model for human bladder cancer. However, the veterinary literature lacks information regarding cross-validation analysis between human and canine large-scale data. Therefore, this research aimed to perform a meta-analysis of the canine literature on bladder cancer, identifying genes and proteins previously evaluated in these studies. In addition, we also performed a cross-validation of the canine transcriptome data and the human data from The Cancer Genome Atlas (TCGA) to identify potential markers for both species. The meta-analysis was performed using the following indexing terms: “bladder” AND “carcinoma” AND “dog” in different international databases, and 385 manuscripts were identified in our initial search. Then, several inclusion criteria were applied, and only 25 studies met these criteria. Among these studies, five presented transcriptome data, and 20 evaluated only isolated genes or proteins. Regarding the studies involving isolated protein analysis, the HER-2 protein was the most studied (3/20), followed by TAG-72 (2/20), COX-2 (2/20), survivin (2/20), and CK7 (2/20), and the remaining nine studies evaluated one isolated protein each. Regarding the cross-validation analysis of human and canine transcriptome data, we identified 35 dysregulated genes, including ERBB2, TP53, EGFR, and E2F2. Our results demonstrate that the canine literature on bladder cancer previously focused on the evaluation of isolated markers with no association with patient survival. This limitation may be related to the lack of a homogenous protocol for treating patients and the lack of follow-up during treatment. In addition, the lack of information regarding tumor muscle invasion can be considered an important limitation when comparing human and canine bladder tumors. Our in silico analysis involving canine and human transcriptome data provided several genes with the potential to be markers for both human and canine bladder tumors, and these genes should be considered for future studies on canine bladder cancer.

Characterization of six canine prostate adenocarcinoma and three transitional cell carcinoma cell lines derived from primary tumor tissues as well as metastasis

Canine prostate adenocarcinoma (PAC) and transitional cell carcinoma (TCC) of prostate and urinary bladder are highly invasive and metastatic tumors of closely neighbored organs. Cell lines are valuable tools to investigate tumor mechanisms and therapeutic approaches in vitro. PAC in dogs is infrequent, difficult to differentiate from TCC and usually characterized by poor prognosis, enhancing the value of the few available cell lines. However, as cell lines adapt to culturing conditions, a thorough characterization, ideally compared to original tissue, is indispensable. Herein, six canine PAC cell lines and three TCC cell lines were profiled by immunophenotype in comparison to respective original tumor tissues. Three of the six PAC cell lines were derived from primary tumor and metastases of the same patient. Further, two of the three TCC cell lines were derived from TCCs invading into or originating from the prostate. Cell biologic parameters as doubling times and chemoresistances to commonly used drugs in cancer treatment (doxorubicin, carboplatin and meloxicam) were assessed. All cell lines were immunohistochemically close to the respective original tissue. Compared to primary tumor cell lines, metastasis-derived cell lines were more chemoresistant to doxorubicin, but equally susceptive to carboplatin treatment. Two cell lines were multiresistant. COX-2 enzyme activity was demonstrated in all cell lines. However, meloxicam inhibited prostaglandin E2 production in only seven of nine cell lines and did neither influence metabolic activity, nor proliferation. The characterized nine cell lines represent excellent tools to investigate PAC as well as TCC in prostate and urinary bladder of the dog. Furthermore, the profiled paired cell lines from PAC primary tumor and metastasis provide the unique opportunity to investigate metastasis-associated changes PAC cells undergo in tumor progression. The combination of nine differently chemoresistant PAC and TCC cell lines resembles the heterogeneity of canine lower urinary tract cancer.

Prostatic Neoplasia in the Intact and Castrated Dog: How Dangerous is Castration?

Elective gonadectomy in the dog is a topic of interest for clinicians, pet-owners, and society. Although canine prostatic neoplasia (CPN) has a low incidence (0.35%), reports of an increased risk for castrated dogs attract attention and cause concern in pet-owners. Our aim is to provide professionals and non-professionals with a detailed description of this possible side effect of gonadectomy in the dog. The mean age at diagnosis of CPN ranges from 8.5 to 11.2 years. Medium to large size breeds are more frequently affected. Symptoms and findings of non-invasive examinations are not pathognomonic, therefore, cytological or histological examinations are needed for diagnosis. Overall, the incidence of metastasis reaches up to 80%, yet lung metastasis reportedly has no negative impact on median survival time (MST). It has been reported that castrated males have a significantly higher MST than intact males. Differences in inclusion criteria for studied populations make a comparison of studies difficult. Citation of odds ratios without consideration of the context of the reference may result in premature conclusions. We conclude that elective gonadectomy of adult male dogs under six years of age cannot be excluded from the veterinary practice due to concern of causing CPN until clear and strong evidence is available.

Lower Urinary Tract Neoplasia

Lower urinary tract neoplasia in companion animals is a debilitating and often life-threatening disease. Tumors of the bladder, urethra, and prostate often occur independently, although extension of these tumors into adjacent regions of the lower urinary tract is documented frequently. The most common lower urinary tract tumor in dogs and cats is transitional cell carcinoma (TCC). In both dogs and cats, TCC affecting the urinary bladder is generally considered to be highly aggressive with both local and metastatic disease potential, and this disease poses unique treatment challenges. Whereas much literature exists regarding the TCC disease process, treatment options, and prognosis in dogs, relatively few studies on feline TCC have been published due to the lower incidence of TCC in this species. Prostate tumors, most commonly adenocarcinomas, occur less commonly in dogs and cats but serve an important role as a comparative model for prostate neoplasia in humans. This article serves as a review of the current information regarding canine and feline lower urinary tract neoplasia as well as the relevance of these diseases with respect to their human counterparts.

Outcome and prognostic factors in medically treated canine prostatic carcinomas: A multi-institutional study

Literature describing medical treatment of canine prostatic carcinoma (PC) is sparse. The aims of this study were to assess outcomes, including time to progression (TTP) and median survival time (MST), of canine PC treated with non-steroidal anti-inflammatory drugs (NSAIDs) and/or chemotherapy, and to identify prognostic factors. Records from 8 institutions were searched for dogs with cytologically or histologically confirmed PC without bladder involvement: 67 dogs were included. Presenting signs were urinary (25), gastrointestinal ([GI], 11) and systemic (3); 16 dogs had GI and urinary signs, 7 dogs had systemic signs with concurrent GI or urinary signs and in 5 dogs the tumour was an incidental finding. Out of 27 dogs, 9 (33%) had positive urine culture. Metastases were identified in 26 dogs to lymph nodes (19), lungs (10), bone (2) and liver (1). Treatment included NSAIDs and chemotherapy (32), NSAIDs alone (31) and chemotherapy alone (4). The overall MST was 82 days (range 9-752) and median TTP was 63 days (range 9-752). Dogs receiving NSAIDs combined with chemotherapy experienced a significantly longer MST (106 vs 51 days; P = .035) and TTP (76 vs 44 days; P = .02) compared to dogs receiving NSAIDs alone. Intact dogs and those with metastatic disease had significantly shorter MST (31 vs 90 days, P = .018 and 49 vs 109 days, P = .037, respectively); intact dogs also had significantly shorter TTP (25 vs 63 days, P = .0003). This study suggests that a combination of NSAIDs and chemotherapy may improve outcomes in canine PC. Metastatic disease and being entire negatively influenced prognosis.

MicroRNA expression profiling in canine prostate cancer

Canine prostate cancer (cPCa) is an untreatable malignant neoplasm resulting in local tissue invasion and distant metastasis. MicroRNAs (miRs) are small non-coding RNAs that function as oncogenes or tumor suppressors. The purpose of this study was to characterize the expression of miRs that are altered in cPCa tissue. The expression levels of 277 mature miRs in prostatic tissue (n=5, respectively) were compared between the non-tumor and tumor groups using real-time PCR. Five miRs (miR-18a, 95, 221, 222 and 330) were up-regulated, but 14 miRs (miR-127, 148a, 205, 299, 329b, 335, 376a, 376c, 379, 380, 381, 411, 487b and 495) were down-regulated specifically in cPCa (P<0.05). These miRs have potential use as early diagnosis markers for cPCa and in miR-based therapy.

Comparative Aspects of BRAF Mutations in Canine Cancers

Activating mutations of the BRAF gene lead to constitutive activation of the MAPK pathway. The characterization and discovery of BRAF mutations in a variety of human cancers has led to the development of specific inhibitors targeting the BRAF/MAPK pathway and dramatically changed clinical outcomes in BRAF-mutant melanoma patients. Recent discovery of BRAF mutation in canine cancers underscores the importance of MAPK pathway activation as an oncogenic molecular alteration evolutionarily conserved between species. A comparative approach using the domestic dog as a spontaneous cancer model will provide new insights into the dysregulation of BRAF/MAPK pathway in carcinogenesis and facilitate in vivo studies to evaluate therapeutic strategies targeting this pathway's molecules for cancer therapy. The BRAF mutation in canine cancers may also represent a molecular marker and therapeutic target in veterinary oncology. This review article summarizes the current knowledge on BRAF mutations in human and canine cancers and discusses the potential applications of this abnormality in veterinary oncology.

Different Growth Patterns of Canine Prostatic Carcinoma Suggests Different Models of Tumor-Initiating Cells

Controversies remain regarding the cell type from which human prostate cancer originates, and many attempts have been made to identify the cellular origin of canine prostate cancer but without definitive proof. This study aims to evaluate the expression of luminal (androgen receptor [AR], cytokeratin [CK]8/18) and basal (CK14, CK5) cell markers in different histologic subtypes of canine prostatic carcinoma (PC) and to suggest the most likely tumor-initiating cells. Normal prostates (n = 8) were characterized by AR+CK8/18+ luminal cells and few CK5+ basal cells, while CK14 was absent. Similar pattern was observed in all 35 prostates with benign prostatic hyperplasia, except few scattered CK14+ basal cells in 13 samples (37.14%). AR was localized in the nucleus of both normal and hyperplastic cells. In 34 samples of PC, the following growth patterns were identified: cribriform (44.12%), solid (32.35%), small acinar/ductal (20.59%), and micropapillary (2.94%). Most PCs expressed AR and CK8/18, while CK5 and CK14 expression was observed in 25% and 20% of cases, respectively. AR revealed a variable intracellular distribution, both nuclear and cytoplasmic. Solid PC was characterized by an undifferentiated or aberrant phenotype with a reduced expression of AR and CK8/18, increased number of CK14+ cells, and 7 antigen expression patterns. This study demonstrated a predominance of differentiated luminal cell types in canine prostatic tumors, although the role of basal cells in prostate carcinogenesis should also be considered. Moreover, few scattered CK5+ cells in AR+CK8/18+ tumors identified the existence of intermediate cells, from which neoplastic transformation may alternatively commence.

All lesions great and small, part 2. Diagnostic cytology in veterinary medicine

This is the second in a two‐part review of diagnostic cytopathology in veterinary medicine. As in human medicine, cytopathology is a minimally invasive, rapid, and cost‐effective diagnostic modality with broad utilization. In this second part, the diagnostic applications of cytology in respiratory, gastrointestinal, genitourinary, endocrine, ocular, and central nervous system tissues are discussed with a section describing fluid analysis in veterinary medicine. As noted in the previous manuscript, which characterized the cytology of the skin/subcutis, musculoskeletal, and lymphoid tissues, the interpretation of veterinary cytology samples must be undertaken with extensive knowledge of the breadth of animal species, including familiarity with the frequency and clinical progression of diseases, both of which can be influenced by species, breed, and husbandry conditions. Similar to part one, this review focuses on the most common domestic companion animal species (dog, cat, and horse) and highlights lesions that are either unique to veterinary species or have relevant correlates in people. The cytologic features and biological behavior of similar lesions are compared, and selected mechanisms of disease and ancillary diagnostics are reviewed when appropriate. Supporting figures illustrate a subset of lesions. While not an exhaustive archive of veterinary cytology, the goal is to give cytopathologists working in human medicine a general impression of correlates and unique entities in veterinary practice. Diagn. Cytopathol. 2014;42:544–552. © 2014 Wiley Periodicals, Inc.

Alterations of C-MYC, NKX3.1, and E-cadherin expression in canine prostate carcinogenesis

The dog (canis lupus familiaris) is the only other species besides humans that develop spontaneous prostatic carcinomas (PCa) at a high frequency. The canine model is primarily utilized for the study of the PCa molecular mechanisms and provides a natural animal model for the study of potential therapies. In humans, the PCa frequently exhibits mutations in the C-MYC and a reduced expression of the E-cadherin and NKX3.1 proteins. This study's objective was to evaluate the NKX3.1, C-MYC, and E-cadherin expression in the canine normal prostate, benign prostatic hyperplasia (BPH), proliferative inflammatory atrophy (PIA) and PCa and to verify differences in expression and subcellular localization of these proteins in the prostatic carcinogenesis. A tissue microarray (TMA) slide was constructed, and immunohistochemistry with antibodies raised against C-MYC, NKX3.1, E-cadherin and p63 was performed using the peroxidase and DAB methods. The C-MYC protein expression was elevated in the cytoplasm and nuclei of the canine PCa and PIA compared with the normal prostate (P = 0.004. The NKX3.1 protein expression was reduced in 94.75% of the PCa and 100% of the PIA compared with the normal prostate (P = 0.0022). In fact, the expression of E-cadherin trended towards a decrease in carcinomas when compared to normal prostate and PIA. By immunohistochemistry, more p63-positive basal cells were observed in the PCa and PIA when compared with the normal prostate (P = 0.0002). This study has demonstrated that the carcinogenesis of canine prostatic tissue may be related to basal cell proliferation, the gain of C-MYC function and the loss of NKX3.1 protein expression.

Metastasis of a Prostatic Carcinoma along an Omental Graft in a Dog

An 11-year-old male American Bulldog was presented for hematuria and tenesmus. It had been treated for chronic bacterial prostatitis with abscessation two years earlier and underwent castration and a prostatic omentalization procedure. There was no histologic evidence of prostatic neoplasia at that time. On physical examination, an enlarged prostate was found by rectal palpation, and it was characterized with ultrasonography and computed tomography. Surgical biopsies were obtained, and histopathology identified prostatic adenocarcinoma. It received carprofen and mitoxantrone chemotherapy in addition to palliative radiation therapy; it was euthanized six weeks later due to a progression of clinical signs. Necropsy findings included marked localized expansion of the prostatic tumor and dissemination of prostatic carcinoma cells throughout the peritoneal cavity along the omental graft with infiltration onto the serosal surfaces of most abdominal viscera and fat. This case represents a previously unreported potential complication of the omentalization procedure wherein carcinoma cells from a prostatic tumor that independently arose after omentalization may have metastasized along the surgically created omental graft.

A specific molecular beacon probe for the detection of human prostate cancer cells

The small-molecule, water-soluble molecular beacon probe 1 is hydrolyzed by the lysate and living cells of human prostate cancer cell lines (LNCaP), resulting in strong green fluorescence. In contrast, probe 1 does not undergo significant hydrolysis in either the lysate or living cells of human nontumorigenic prostate cells (RWPE-1). These results, corroborated by UV-Vis spectroscopy and fluorescent microscopy, reveal that probe 1 is a sensitive and specific fluorogenic and chromogenic sensor for the detection of human prostate cancer cells among nontumorigenic prostate cells and that carboxylesterase activity is a specific biomarker for human prostate cancer cells.

Development of a brain metastatic canine prostate cancer cell line

BACKGROUND

Prostate cancer in men has a high mortality and morbidity due to metastatic disease. The pathobiology of prostate cancer metastasis is not well understood and cell lines and animal models that recapitulate the complex nature of the disease are needed. Therefore, the goal of the study was to establish and characterize a new prostate cancer line derived from a dog with spontaneous prostate cancer.

METHODS

A new cell line (Leo) was derived from a dog with spontaneous prostate cancer. Immunohistochemistry and PCR were used to characterize the primary prostate cancer and xenografts in nude mice. Subcutaneous tumor growth and metastases in nude mice were evaluated by bioluminescent imaging, radiography and histopathology. In vitro chemosensitivity of Leo cells to therapeutic agents was measured.

RESULTS

Leo cells expressed the secretory epithelial cytokeratins (CK)8, 18, and ductal cell marker, CK7. The cell line grew in vitro (over 75 passages) and was tumorigenic in the subcutis of nude mice. Following intracardiac injection, Leo cells metastasized to the brain, spinal cord, bone, and adrenal gland. The incidence of metastases was greatest to the central nervous system (80%) with a lower incidence to bone (20%) and the adrenal glands (16%). In vitro chemosensitivity assays demonstrated that Leo cells were sensitive to Velcade and an HDAC-42 inhibitor with IC(50) concentrations of 1.9 nm and 0.95 µm, respectively.

CONCLUSION

The new prostate cancer cell line (Leo) will be a valuable model to investigate the mechanisms of the brain and bone metastases.

Histopathological and immunohistochemical characterization of canine prostate cancer

BACKGROUND

In this study we try to identify the origin of canine prostate cancer (cPC) by classifying the tumors histological subtypes and relate these subtypes to their combined expressional characteristics of several tissue specific and differentiation markers.

METHODS

cPCs were examined histomorphologically and by immunohistochemical detection of the cytokeratin markers CK14, HMWCK, CK5, CK18, and CK7, and of the markers UPIII, PSA and PSMA.

RESULTS

Histopathologically, six growth patterns could be differentiated. The most frequent patterns were solid, cribriform and micropapillary growth patterns, while sarcomatoid, small acinar/ductal, and tubulo-papillary growth patterns were less frequent present. Solid growth patterns were significantly (P = 0.027) more often seen in castrated dogs. Immunohistochemically, about half of the cPC cases showed expression of PSA (8/20) and PSMA (10/20); 85% and 60% of the cPC expressed UPIII (17/20) and CK7 (12/20), while 13 and 12 cPC expressed CK5 and CK14, respectively; all cPC expressed CK18. CK14 was significantly more often and UPIII less frequent expressed in the solid growth patterns than in the micropapillary and cribriform patterns, respectively.

CONCLUSIONS

Canine prostate cancer appear to be more aggressive and of a less differentiated type than most common human prostate cancers. Comparing the expression patterns of the markers in cPC to those in normal canine prostate tissue, cPC most likely originates from the collecting ducts rather than from the peripheral acini. Given also the fact that canine prostate cancer is unresponsive to androgen withdrawal therapy, canine prostate cancer mostly resembles human, androgen refractory, poorly differentiated prostate cancer.

Comparative characterization of the canine normal prostate in intact and castrated animals

BACKGROUND

Prostate diseases in the dog are generally regarded as representative for their human counterparts. We characterized the normal canine prostate in comparison to the normal human prostate.

METHODS

Prostates of dogs were examined histomorphologically and by immunohistochemical detection of the markers CK14, HMWCK, CK5, CK18, CK7, UPIII, PSA, and PSMA.

RESULTS

Histomorphologically, the canine prostate lacks the human zonal differentiation, has much more prominent acini, while comprising less stromal tissue. In general, the canine prostate epithelium displayed a highly differentiated character, with no cells expressing CK14, minimal amounts of cells expressing HMWCK/CK5 and the vast majority of cells expressing CK18 and PSA. After castration, the prostate epithelium regressed, and the remaining tubules were largely populated by cells showing a ductal phenotype (HMWCK+/CK5+/CK18+/CK7+).

CONCLUSIONS

The human and canine prostate are histologically differently organized. The general scheme of cellular differentiation of the prostate epithelium may however be applicable to both species.

A population study of neutering status as a risk factor for canine prostate cancer

BACKGROUND

Prostate cancer has been reported to occur more commonly in neutered than intact male dogs in several case series. This study was undertaken to evaluate risk of prostate cancer in a large population database. The hypothesis was that castration is a risk factor for prostate cancer in male companion dogs.

METHODS

Data were derived from recorded visits to North American veterinary teaching hospitals. The Veterinary Medical Databases (VMDB) were queried to yield male dogs with urinary bladder transitional cell carcinoma (TCC), prostate adenocarcinoma (ACA), prostate TCC, prostate carcinoma (CA), and prostate tumors. A second query yielded all male dogs over the age of 4 years without a diagnosis of urinary tract cancer. These populations were compared to determine relative risks for developing each disease, singly and collectively, associated with neutering status. Odds ratios were calculated for breed as a risk factor.

RESULTS

Neutered males had a significantly increased risk for each form of cancer. Neutered males had an odds ratio of 3.56 (3.02-4.21) for urinary bladder TCC, 8.00 (5.60-11.42) for prostate TCC, 2.12 (1.80-2.49) for prostate adenocarcinoma, 3.86 (3.13-4.16) for prostate carcinoma, and 2.84 (2.57-3.14) for all prostate cancers. Relative risks were highly similar when cases were limited to those with a histologically confirmed diagnosis.

CONCLUSIONS

Breed predisposition suggests that genetic factors play a role in the development of prostate cancer. The risk associated with being neutered is highest for TCC, supporting previous work identifying the urothelium and ductular rather than acinar epithelium as the source of these tumors.

Herapin-binding proteins of canine seminal plasma

Heparin-binding proteins (HBP) from seminal plasma have been expected to participate in modulation of the acrosomal reaction, and have been correlated with fertility in some species. However, they have not been described in the dog. The aim of this study was to document the HBPs of canine seminal plasma. Six pooled samples of seminal plasma from three crossbred dogs were used. The HBPs were isolated by heparin affinity chromatography and the fractions recovered were pooled. One-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was carried out on 12 and 18% vertical minigels. The stained gels were scanned and the molecular weight (kDa) values for each band within a lane were calculated by image analysis software. The electrophoresis analysis of the pooled eluded fractions identified 19 bands, with molecular weights varying from 61.5 to 5.2 kDa. Previous studies, using one-dimensional SDS-PAGE, identified two bands (67 and 58.6 kDa), which were positively correlated with some semen parameters (sperm motility, sperm vigor, percentage of morphologically normal sperm and plasma membrane integrity). The 61.5 kDa band detected in the present study apparently corresponded to the 58.6 kDa band identified previously. Canine seminal plasma contained HBP; since HBP modulate the acrosome reaction in other species, they may have the same function in the dog. Further studies are necessary to better characterize this protein and determine if it is associated with fertility in the dog.