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

Alterations in Tumor Aggression Following Androgen Receptor Signaling Restoration in Canine Prostate Cancer Cell Lines

In prostate cancer (PCa), androgens upregulate tumorigenesis, whereas in benign tissue, the revival of androgen receptor (AR) signaling suppresses aggressive behaviors, suggesting therapeutic potential. Dogs, natural PCa models, often lack AR in PCa. We restored AR in dog PCa to investigate resultant characteristics. Three AR-null canine PCa lines (1508, Leo, 1258) were transfected with canine wild-type AR and treated with dihydrotestosterone (DHT). In 1508, AR restoration decreased clonogenicity (p = 0.03), viability (p = 0.004), migration (p = 0.03), invasion (p = 0.01), and increased expression of the tumor suppressor NKX3.1, an AR transcriptional target (p = 0.001). In Leo, AR decreased clonogenicity (p = 0.04) and the expression of another AR transcriptional target FOLH1 (p < 0.001) and increased the expression of NKX3.1 (p = 0.01). In 1258, AR increased migration (p = 0.006) and invasion (p = 0.03). Epithelial-mesenchymal transition (EMT) marker (Vimentin, N-cadherin, SNAIL1) expression increased with AR restoration in Leo and 1258 but not 1508; siRNA vimentin knockdown abrogated AR-induced 1258 migration only. Overall, 1508 showed AR-mediated tumor suppression; AR affected proliferation in Leo but not migration or invasion; and EMT and AR regulated migration and invasion in 1258 but not proliferation. This study highlights the heterogeneous nature of PCa in dogs and cell line-specific effects of AR abrogation on aggressive behaviors.

Advances in organoid technology for veterinary disease modeling

Organoids are in vitro organ-like structures that faithfully recapitulate many characteristics of a specific organ. During the past decades, major progress has been accomplished in establishing three-dimensional (3D) culture systems toward stem cell-derived organoids. As a significant technological breakthrough, these amazing 3D organoid constructs bridge the conventional 2D in vitro models and in vivo animal models and provide an unprecedented opportunity to investigate the complexities of veterinary diseases ranging from their pathogenesis to the prevention, therapy, or even future organ replacement strategies. In this review, we briefly discuss several definitions used in organoid research and highlight the currently known achievements in modeling veterinary diseases, including infectious and inflammatory diseases, cancers, and metabolic diseases. The applications of organoid technology in veterinary disease modeling are still in their infancy stage but the future is promising.

MDR1 Inhibition Reverses Doxorubicin-Resistance in Six Doxorubicin-Resistant Canine Prostate and Bladder Cancer Cell Lines

Acquired chemoresistance during chemotherapy, often accompanied by cross- and multi-resistance, limits therapeutic outcomes and leads to recurrence. In order to create in vitro model systems to understand acquired doxorubicin-resistance, we generated doxorubicin-resistant sublines of canine prostate adenocarcinoma and urothelial cell carcinoma cell lines. Chemoresistance to doxorubicin, cross-resistance to carboplatin, and the reversibility of the acquired resistance by the specific MDR1-inhibitor tariquidar were quantified in metabolic assays. Resistance mechanisms were characterized by expression of the efflux transporters MDR1 and RALBP1, as well as the molecular target of doxorubicin, TOP2A, with qPCR and Western blotting. Six out of nine cell lines established stable resistance to 2 µM doxorubicin. Drug efflux via massive MDR1 overexpression was identified as common, driving resistance mechanism in all sublines. MDR1 inhibition with tariquidar extensively reduced or reversed the acquired, and also partly the parental resistance. Three cell lines developed additional, non-MDR1-dependent resistance. RALBP1 was upregulated in one resistant subline at the protein level, while TOP2A expression was not altered. Combination therapies aiming to inhibit MDR1 activity can now be screened for synergistic effects using our resistant sublines. Nevertheless, detailed resistance mechanisms and maintained molecular target expression in the resistant sublines are still to be examined.

Establishment and characterization of urothelial carcinoma cell lines with and without BRAF mutation (V595E) in dogs

Each 5 urothelial carcinoma (UC) cell lines with and without the v-Raf murine sarcoma virus oncogene homolog B (BRAF) gene mutation (V595E) were established and examined V595E-related tumorigenic characteristics in dogs. No typical morphological features were observed in cloned cells with and without V595E. The cell proliferation of both cloned cells showed logarithmic growth curve and those doubling time were 24.9 ± 4.1 h in V595E ( +) and 29.3 ± 11.3 h in V595E ( -). On the growth curve of xenotransplanted tumor in severe combined immunodeficiency mice, 3 out of 5 V595E ( +) and 2 out of 5 V595E ( -) cloned cells revealed gradually and remarkably increasing curve, indicating clearly tumorigenicity. The xenotransplanted tumors with V595E ( +) showed typical features of UC, such as solid proliferation of pleomorphic tumor cells, formation of papillary structure, and glandular structure. Additionally, various vascular formation was observed, probably indicating an advanced growth phase of UC. In mitogen-activated protein kinase (MAPK) signaling pathway, cytoplasmic phosphorylated-BRAF (pBRAF) and cytoplasmic and nuclear phosphorylated-ERK1/2 (pERK1/2) were detected in all 4 tumors with V595E ( +), whereas only cytoplasmic and nuclear pERK1/2 was detected in tumors with V595E ( -). Since V595E can directly activate MAPK signaling pathway, coincidence of V595E with pBRAF (phosphor Thr598/Ser601) indicates acquired resistance to BRAF inhibitors. These established UC cell lines, especially V595E ( +) cell lines, are useful tool for understanding pathophysiological states and controlling therapeutic manners of UC in dogs.

Comparative Pathobiology of Canine and Human Prostate Cancer: State of the Art and Future Directions

First described in 1817, prostate cancer is considered a complex neoplastic entity, and one of the main causes of death in men in the western world. In dogs, prostatic carcinoma (PC) exhibits undifferentiated morphology with different phenotypes, is hormonally independent of aggressive character, and has high rates of metastasis to different organs. Although in humans, the risk factors for tumor development are known, in dogs, this scenario is still unclear, especially regarding castration. Therefore, with the advent of molecular biology, studies were and are carried out with the aim of identifying the main molecular mechanisms and signaling pathways involved in the carcinogenesis and progression of canine PC, aiming to identify potential biomarkers for diagnosis, prognosis, and targeted treatment. However, there are extensive gaps to be filled, especially when considering the dog as experimental model for the study of this neoplasm in humans. Thus, due to the complexity of the subject, the objective of this review is to present the main pathobiological aspects of canine PC from a comparative point of view to the same neoplasm in the human species, addressing the historical context and current understanding in the scientific field.

Evaluation of the therapeutic potential of masitinib and expression of its specific targets c-Kit, PDGFR-α, PDGFR-β, and Lyn in canine prostate cancer cell lines

Canine prostate cancer is classified into adenocarcinoma, transitional cell carcinoma with prostatic involvement, and mixed forms. Early metastatic spread leads to poor prognosis and limited treatment options. Masitinib is approved for the treatment of canine mast cell tumours and inhibits tyrosine kinase c-Kit, tyrosine-protein kinase Lyn (Lyn), and platelet-derived growth factor receptors alpha and beta (PDGFR-α, PDGFR-β), which are known to be expressed in canine prostate cancer. The aim of this study was to evaluate masitinib in an in vitro model consisting of cell lines from primary prostate adenocarcinoma, the associated lymph node metastasis of the same patient, and transitional cell carcinoma. To assess the suitability of the model system, the targets of masitinib were investigated by immunocytochemistry in the cell lines and by immunohistochemistry in the respective formalin-fixed, paraffin-embedded (FFPE) original neoplastic tissue. After exposure to masitinib, cell viability, cell count, apoptosis induction, and protein expression of c-Kit, Lyn, PDGFR-α, and PDGFR-β were assessed. To hedge the efficacy, two application protocols of masitinib (single application or 12-h double-dose regimen) were compared. Immunocytochemical and immunohistochemical analysis revealed increased Lyn, PDGFR-α, and PDGFR-β expression in cell lines and FFPE original neoplastic tissue compared to healthy prostate tissue. Masitinib exposure increased apoptosis, while the cell counts and cell viability decreased in a dose- and application interval-dependent manner, with increased impact in the 12-h double-dose regimen. These in vitro effects of masitinib in canine prostate cancer and associated metastasis support further in vivo research and modifications of the clinical treatment protocol in future studies.

Characteristics and Applications of Canine In Vitro Models of Bladder Cancer in Veterinary Medicine: An Up-to-Date Mini Review

Simple Summary

Bladder cancer (BC) in dogs is often lethal at the time of diagnosis. Therefore, there is a constant need for novel research on improvements of its characterization and treatment. Due to high cost and limited number of available dog patients, in vitro models of canine BC have been increasingly used for the last 25 years. In the present article, we present existing in vitro models of canine BC, including available simple (two-dimensional) and more complex (three-dimensional) models.

Abstract

Bladder cancer (BC) constitutes approximately 2% of all spontaneously occurring cancers in dogs. It is characterized by a devastating clinical course in most cases, which emphasizes a constant need for the development of novel methods of disease characterization and treatment. Over the past years, advances in cell engineering have resulted in the development of various canine in vitro models of BC, emerging as complements for in vivo research. In this article, we aimed to review the available data on existing in vitro models of canine BC, focusing primarily on their characteristics, applications in veterinary medicine, as well as advantages and disadvantages. The most commonly used in vitro models of canine BC comprise immortalized cell lines grown as adherent monolayers. They provide an unlimited supply of research material, however, they do not faithfully reflect the conditions prevailing in vivo, since the spatial cellular interactions are lost. The importance of the three-dimensional (3D) features of solid tumors in relation to carcinogenesis or drug response process has resulted in the development of the first canine 3D models of BC available for in vitro research. So far, results obtained with in vitro and in vivo research should be interpreted together. With the constantly growing complexity of in vitro models of BC cancer, animal-based research might be reduced in the future.

RNA-seq of nine canine prostate cancer cell lines reveals diverse therapeutic target signatures

BACKGROUND

Canine prostate adenocarcinoma (PAC) and transitional cell carcinoma (TCC) are typically characterized by metastasis and chemoresistance. Cell lines are important model systems for developing new therapeutic strategies. However, as they adapt to culturing conditions and undergo clonal selection, they can diverge from the tissue from which they were originally derived. Therefore, a comprehensive characterization of cell lines and their original tissues is paramount.

METHODS

This study compared the transcriptomes of nine canine cell lines derived from PAC, PAC metastasis and TCC to their respective original primary tumor or metastasis tissues. Special interests were laid on cell culture-related differences, epithelial to mesenchymal transition (EMT), the prostate and bladder cancer pathways, therapeutic targets in the PI3K-AKT signaling pathway and genes correlated with chemoresistance towards doxorubicin and carboplatin.

RESULTS

Independent analyses for PAC, PAC metastasis and TCC revealed 1743, 3941 and 463 genes, respectively, differentially expressed in the cell lines relative to their original tissues (DEGs). While genes associated with tumor microenvironment were mostly downregulated in the cell lines, patient-specific EMT features were conserved. Furthermore, examination of the prostate and bladder cancer pathways revealed extensive concordance between cell lines and tissues. Interestingly, all cell lines preserved downstream PI3K-AKT signaling, but each featured a unique therapeutic target signature. Additionally, resistance towards doxorubicin was associated with G2/M cell cycle transition and cell membrane biosynthesis, while carboplatin resistance correlated with histone, m- and tRNA processing.

CONCLUSION

Comparative whole-transcriptome profiling of cell lines and their original tissues identifies models with conserved therapeutic target expression. Moreover, it is useful for selecting suitable negative controls, i.e., cell lines lacking therapeutic target expression, increasing the transfer efficiency from in vitro to primary neoplasias for new therapeutic protocols. In summary, the dataset presented here constitutes a rich resource for canine prostate and bladder cancer research.

Comparative pathology of dog and human prostate cancer

Though relatively rare in dogs, prostate cancer (PCa) is the most common non-cutaneous cancer in men. Human and canine prostate glands share many functional, anatomical and physiological features. Due to these similarities, canine PCa has been proposed as a model for PCa in men. PCa is typically androgen-dependent at diagnosis in men and for this reason, androgen deprivation therapies (ADT) are important treatments for advanced PCa in men. In contrast, there is some evidence that PCa is diagnosed more commonly in castrate dogs, at which point, limited therapeutic options are available. In men, a major limitation of current ADT is that progression to a lethal and incurable form of PCa, termed castrate-resistant prostate cancer (CRPC), is common. There is, therefore, an urgent need for a better understanding of the mechanism of PCa initiation and progression to CRPC to enable the development of novel therapeutic approaches. This review focuses on the functional, physiological, endocrine and histopathological similarities and differences in the prostate gland of these species. In particular, we focus on common physiological roles for androgen signalling in the prostate of men and dogs, we review the short- and longer-term effects of castration on PCa incidence and progression in the dog and relate how this knowledge may be relevant to understanding the mechanisms of CRPC in men.

Ablation of Red Stable Transfected Claudin Expressing Canine Prostate Adenocarcinoma and Transitional Cell Carcinoma Cell Lines by C-CPE Gold-Nanoparticle-Mediated Laser Intervention

Claudin (CLDN) proteins are commonly expressed in cancers and targeted in novel therapeutic approaches. The C-terminal of Clostridium perfringens enterotoxin (C-CPE) efficiently binds several claudins. In this study, recombinant C-CPE conjugated to gold nanoparticles (AuNPs) has been used for prostate adenocarcinoma (PAC) and transitional cell carcinoma (TCC) cell killing in vitro using gold-nanoparticle-mediated laser perforation (GNOME-LP). A PAC and TCC cell lines, as well as red fluorescence variants, allowing deep tissue imaging, were used. CLDN-3, -4, and -7 expression was confirmed by qPCR and immunofluorescences. The binding of C-CPE-AuNPs complexes on the cell surface was examined by scanning electron microscopy (SEM). Further, transcriptome analysis was carried out to evaluate the effect of C-CPE binder on the biological response of treated cells. Directed C-CPE-AuNP binding verified the capability to target CLDN receptors. Transcriptome analysis showed that C-CPE binding may activate immune and inflammatory responses but does not directly affect cell survival. Cancer cells ablation was demonstrated using a combination of GNOME-LP and C-CPE-AuNPs treatment reducing tumor cell viability to less than 10% depending on cell line. The fluorescent cell lines and the verified proof of concept in vitro provide the basis for perspective xenograft studies in an animal model.

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.

Metformin and sodium dichloroacetate effects on proliferation, apoptosis, and metabolic activity tested alone and in combination in a canine prostate and a bladder cancer cell line

An important approach in tumor therapy is combining substances with different action mechanisms aiming to enhance the antineoplastic effect, decrease the therapeutic dosage, and avoid resistance mechanisms. Moreover, evaluating compounds already approved for the treatment of non-neoplastic diseases is promising for new antineoplastic therapies. Sodium dichloroacetate (DCA) reactivates oxidative phosphorylation in the cancer cell mitochondria, reducing apoptosis resistance in cancer cells. Furthermore, metformin inhibits the proliferation of tumor cells and CD133+ cancer -stem-like cells. In the present study, we evaluated the independent and synergistic effect of metformin and DCA on the metabolic activity, cell proliferation, and apoptosis of a canine prostate adenocarcinoma (Adcarc1258) and a transitional cell carcinoma cell line (TCC1506) in comparison to a primary canine fibroblast culture. Determining metformin uptake in tumor cells was performed by quantitative HPLC. Depending on the dosage, metformin as a single agent inhibited the metabolic activity and cell proliferation of the tumor cells, showing only minor effects on the fibroblasts. Furthermore, 1 mM metformin increased apoptosis over 96 h in the tumor cell lines but not in fibroblasts. Additionally, metformin uptake into the tumor cells in vitro was measurable by quantitative HPLC. Synergistic effects for the combination therapy were observed in both neoplastic cell lines as well as in the fibroblasts. Based on these results, metformin might be a promising therapeutic agent for canine urogenital tumors. Further studies on kinetics, toxicology, bioavailability, and application of metformin in dogs are necessary.

Evaluation of combination protocols of the chemotherapeutic agent FX-9 with azacitidine, dichloroacetic acid, doxorubicin or carboplatin on prostate carcinoma cell lines

The isoquinolinamine FX-9 is a novel potential chemotherapeutic agent showing antiproliferative effects against hematologic and prostate cancer cell lines such as B- and T-acute lymphoblastic leukemia and prostate cancer (PC) of different species. Interestingly, FX-9 shows no hemolytic activity and low toxicity in benign adherent cells. The detailed FX-9 molecular mode of action is currently not fully understood. But application on neoplastic cells induces pro-apoptotic and antimitotic effects. Canine prostate cancer (cPC) represents a unique spontaneous occurring animal model for human androgen-independent PC. Human androgen-independent PC as well as cPC are currently not satisfactorily treatable with chemotherapeutic protocols. Accordingly, the evaluation of novel agent combinations bears significant potential for identifying novel treatment strategies. In this study, we combined FX-9 with the currently approved therapeutic agents doxorubicin, carboplatin, the demethylating substance azacitidine as well as further potentially antitumorigenic agents such as dichloroacetic acid (DCA) in order to evaluate the respective synergistic potential. The combinations with 1–5 μM FX-9 were evaluated regarding the effect after 72 hours on cell viability, cell count and apoptotic/necrotic cells in two human prostate cancer cell lines (LNCaP, PC-3) and a canine prostate cancer cell line (Adcarc1258) representing androgen-dependent and -independent PC/cPC forms. FX-9 in combination with azacitidine decreases cell viability and increases cell death with positive Bliss values. Furthermore, this decreases the cell count with neutral Bliss values on PC-3. Carboplatin in combination with FX-9 reduces cell viability with a neutral Bliss value and increases cell death on LNCaP with calculated positive Bliss values. DCA or doxorubicin in combination with FX-9 do not show synergistic or additive effects on the cell viability. Based on these results, azacitidine or carboplatin in combination with FX-9 offers synergistic/additive efficacy against prostate adenocarcinoma cell lines in vitro. The beneficial effects of both combinations are worth further investigation.

PDA Indolylmaleimides Induce Anti-Tumor Effects in Prostate Carcinoma Cell Lines Through Mitotic Death

Castrate resistant prostate cancer in men shares several characteristics with canine prostate cancer (PCa). Due to current insufficient therapies, evaluating novel therapeutic agents for late-stage PCa is of considerable interest for both species. PDA indolylmaleimides showed anticancer effects in several neoplastic cell lines. Herein, a comparative characterization of PDA-66 and PDA-377 mediated effects was performed in human and canine PCa cell lines, which is also the first detailed characterization of these agents on cells derived from solid tumors in general. While PDA-377 showed only weak growth inhibition on human PCa cell lines, PDA-66 inhibited proliferation and induced apoptosis in human and canine cell lines with concentrations in the low micromolar range. Morphological characterization and whole transcriptome sequencing revealed that PDA-66 induces mitotic death through its microtubule-depolymerizing ability. PDA-66 appears to be a worthwhile anti-mitotic agent for further evaluation. The similarities in cellular and molecular response observed in the cell lines of both origins form a solid basis for the use of canine PCa in vivo models to gain valuable interchangeable data to the advantage of both species.