R132 mutations in canine isocitrate dehydrogenase 1 (IDH1) lead to functional changes

Glioma is the second most common intracranial neoplasia in dogs, but the pathogenic mechanisms remain unclear. In humans, isocitrate dehydrogenase 1 (IDH1) is frequently mutated in gliomas. Although almost all human IDH1 mutations have been identified as involving the Arg132 codon, few studies have reported structural, functional, and mutational information for canine IDH1. Therefore, in this study, we cloned the canine IDH1 homologue and used PCR mutagenesis to substitute the wildtype (WT) Arg132 with His (R132H) or Ser (R132S). WT and mutated IDH1 were overexpressed in HeLa cells, and their presence was confirmed by immunoblotting and immunocytochemistry using mutation-specific antibodies. The IDH1 activity between WT, R132H, and R132S transfectants was compared by measuring the production of NADH and NADPH. NADPH production in R132H and R132S transfectants was lower than that in WT, but NADH levels were not significantly different. Finally, we detected increased expression of hypoxia inducible factor 1 alpha (HIF-1α) in the R132H and R132S transfectants. These results indicated that the canine IDH1 Arg132 mutation has the potential to induce carcinogenesis in canine somatic cells.

Functional alteration of canine isocitrate dehydrogenase 2 (IDH2) via an R174K mutation

Gliomas are common intracranial neoplasias in dogs. However, the underlying pathogenic mechanisms remain unclear. In humans, isocitrate dehydrogenase 2 (IDH2) is often mutated in gliomas. Although almost human IDH2 mutations have been identified at the Arg172 codon, few studies have reported structural, functional or mutational information for canine IDH2. In this study, we cloned the full-length canine IDH2 (cIDH2) cDNA and substituted wild type Arg174 (cIDH2 WT: corresponding to R172 of human IDH2) with Lys (cIDH2 R174K). The cIDH2 WT and R174K proteins were overexpressed in HeLa cells, and their presence was confirmed using an anti-human IDH2-WT mAb (clone: KrMab-3) and an anti-IDH2-R172K mAb (clone: KMab-1). The IDH2 activity between cIDH2 WT and cIDH2 R174K transfectants was compared by measuring the production of NADH and NADPH. NADPH production was lower for cIDH2 R174K than that for cIDH2 WT transfectants. Finally, we detected increased expression of hypoxia inducible factor-1 alpha (HIF-1α) in cIDH2 R174K transfectants. This indicates that mutations at R174 can potentially induce carcinogenesis in canine somatic cells.

Disseminated histiocytic sarcoma with hemophagocytosis in a rabbit

A 7-year-old female domestic rabbit suffered from labored respiration, poor appetite, mild anemia and thrombocytopenia. Radioscopic examination revealed masses in multiple locations including the intrapleural cavity and spleen. Forty-three days after the first visit to a private veterinary clinic, the rabbit died of severe respiratory distress. Microscopically, all of the masses were composed of round to polygonal neoplastic cells with distinct cell borders that were arranged in a sheet pattern. Multinucleated giant neoplastic cells were often observed. Some neoplastic cells had phagocytozed one or more erythrocytes. Immunohistochemical staining revealed that the neoplastic cells expressed vimentin, CD204, Iba-1 and lysozyme, but not CD163. Based on the morphological and immunohistochemical findings, this case was diagnosed as disseminated histiocytic sarcoma with hemophagocytosis.

Canine REIC/Dkk-3 interacts with SGTA and restores androgen receptor signalling in androgen-independent prostate cancer cell lines

Background

The pathological condition of canine prostate cancer resembles that of human androgen-independent prostate cancer. Both canine and human androgen receptor (AR) signalling are inhibited by overexpression of the dimerized co-chaperone small glutamine-rich tetratricopeptide repeat-containing protein α (SGTA), which is considered to cause the development of androgen-independency. Reduced expression in immortalised cells (REIC/Dkk-3) interferes with SGTA dimerization and rescues AR signalling. This study aimed to assess the effects of REIC/Dkk-3 and SGTA interactions on AR signalling in the canine androgen-independent prostate cancer cell line CHP-1.

Results

Mammalian two-hybrid and Halo-tagged pull-down assays showed that canine REIC/Dkk-3 interacted with SGTA and interfered with SGTA dimerization. Additionally, reporter assays revealed that canine REIC/Dkk-3 restored AR signalling in both human and canine androgen-independent prostate cancer cells. Therefore, we confirmed the interaction between canine SGTA and REIC/Dkk-3, as well as their role in AR signalling.

Conclusions

Our results suggest that this interaction might contribute to the development of a novel strategy for androgen-independent prostate cancer treatment. Moreover, we established the canine androgen-independent prostate cancer model as a suitable animal model for the study of this type of treatment-refractory human cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1094-4) contains supplementary material, which is available to authorized users.

Identification of tumor-initiating cells derived from two canine rhabdomyosarcoma cell lines

Cancer stem cells or tumor-initiating cells (TICs) are a small subpopulation of cells that have the capacity to self-renew, differentiate and initiate tumors. These cells may function in tumor initiation, aggression and recurrence. Whether spheres derived from canine rhabdomyosarcoma cells have stem cell-like properties is unclear. We induced sphere formation in the canine rhabdomyosarcoma cell lines, CMS-C and CMS-J, and characterized the spheres in vitro and in vivo. Sphere-forming cells were more resistant to vincristine, mitoxantrone and doxorubicin than adherent cells. Xenograft transplantation demonstrated that 1 × 10³ sphere-forming cells derived from CMS-C were sufficient for tumor formation. The sphere assay showed that the sphere-forming cells were present in these tumors. These results suggest that the spheres derived from canine rhabdomyosarcoma cells may possess characteristics of TICs. This study provides the foundation for elucidating the contribution of TICs to rhabdomyosarcoma tumorigenesis.

Pancreatic neuroendocrine carcinoma with exocrine differentiation in a young cat

A 35-mo-old spayed female mixed-breed cat with continuous vomiting, emaciation, and abdominal distention for 2 wk was presented to a private veterinary clinic for evaluation. At 71 d after the initial visit, the cat died with anemia, jaundice, and hypoalbuminemia, and was subjected to autopsy. Grossly, numerous firm masses, 0.5-2.5 cm diameter, were randomly located in the left lobe of the pancreas. Histologic examination revealed that the pancreatic mass consisted of 2 tumor cell types: mostly small round cells with a minority of epithelial cells. The small cells were arranged in nests of various sizes, which were separated by thin fibrous stroma, and had small, round, hyperchromatic nuclei, scant cytoplasm containing argyrophilic granules, and often formed rosettes. The epithelial cells formed luminal structures. Metastases were observed in the liver, greater omentum, and pancreatic, gastric, pulmonary, and mediastinal lymph nodes. Immunohistochemical examination revealed that the small cells were positive for vimentin, neuron-specific enolase, chromogranin A, cytokeratin (CK) AE1/AE3, and trypsin, whereas the epithelial cells were positive for AE1/AE3, trypsin, CK19, and nestin. Ultrastructurally, the small cells contained abundant electron-dense granules, ~200 nm diameter, whereas the epithelial cells had apical microvilli and numerous zymogen granules, ~300 nm diameter. These findings indicated that the tumor was a pancreatic neuroendocrine carcinoma with exocrine differentiation and systemic metastases.

Oncocytic carcinoma of the salivary gland in a dog

A 3-y-old male miniature Dachshund was presented with an ~0.8 cm diameter mass in the right mandibular region. Fourteen months later, the mass was 5 × 4 × 3 cm. Grossly, the mass was encapsulated and was homogeneously gray-white on cut surface. Microscopically, the mass was composed of large, round to polygonal tumor cells that were arranged in solid nests and cords separated by a fibrovascular stroma. Tumor cells had large, round, hypochromatic nuclei containing large prominent nucleoli and abundant eosinophilic cytoplasm containing dark blue granules visible with phosphotungstic acid-hematoxylin stain. Metastasis was observed in the mandibular lymph node. Immunohistochemically, tumor cells were positive for CK AE1/AE3, low-molecular-weight CK (CAM5.2), E-cadherin, mitochondria ATPase beta subunit, and S100, but were negative for vimentin, carcinoembryonic antigen, p63, CK14, CD10, and chromogranin A. Ultrastructurally, tumor cells contained numerous mitochondria. Therefore, the tumor was diagnosed as an oncocytic carcinoma of the mandibular gland.

Tumor suppressor REIC/DKK-3 and co-chaperone SGTA: Their interaction and roles in the androgen sensitivity

REIC/DKK-3 is a tumor suppressor, however, its intracellular physiological functions and interacting molecules have not been fully clarified. Using yeast two-hybrid screening, we found that small glutamine-rich tetratricopeptide repeat-containing protein α (SGTA), known as a negative modulator of cytoplasmic androgen receptor (AR) signaling, is a novel interacting partner of REIC/DKK-3. Mammalian two-hybrid and pull-down assay results indicated that the SGTA-REIC/DKK-3 interaction involved the N-terminal regions of both REIC/DKK-3 and SGTA and that REIC/DKK-3 interfered with the dimerization of SGTA, which is a component of the AR complex and a suppressor of dynein motor-dependent AR transport and signaling. A reporter assay in human prostate cancer cells that displayed suppressed AR signaling by SGTA showed recovery of AR signaling by REIC/DKK-3 expression. Considering these results and our previous data that REIC/DKK-3 interacts with the dynein light chain TCTEX-1, we propose that the REIC/DKK-3 protein interferes with SGTA dimerization, promotes dynein-dependent AR transport and then upregulates AR signaling.

Molecular Characterization of the Cytidine Monophosphate-N-Acetylneuraminic Acid Hydroxylase (CMAH) Gene Associated with the Feline AB Blood Group System

Cat’s AB blood group system (blood types A, B, and AB) is of major importance in feline transfusion medicine. Type A and type B antigens are Neu5Gc and Neu5Ac, respectively, and the enzyme CMAH participating in the synthesis of Neu5Gc from Neu5Ac is associated with this cat blood group system. Rare type AB erythrocytes express both Neu5Gc and Neu5Ac. Cat serum contains naturally occurring antibodies against antigens occurring in the other blood types. To understand the molecular genetic basis of this blood group system, we investigated the distribution of AB blood group antigens, CMAH gene structure, mutation, diplotypes, and haplotypes of the cat CMAH genes. Blood-typing revealed that 734 of the cats analyzed type A (95.1%), 38 cats were type B (4.9%), and none were type AB. A family of three Ragdoll cats including two type AB cats and one type A was also used in this study. CMAH sequence analyses showed that the CMAH protein was generated from two mRNA isoforms differing in exon 1. Analyses of the nucleotide sequences of the 16 exons including the coding region of CMAH examined in the 34 type B cats and in the family of type AB cats carried the CMAH variants, and revealed multiple novel diplotypes comprising several polymorphisms. Haplotype inference, which was focused on non-synonymous SNPs revealed that eight haplotypes carried one to four mutations in CMAH, and all cats with type B (n = 34) and AB (n = 2) blood carried two alleles derived from the mutated CMAH gene. These results suggested that double haploids selected from multiple recessive alleles in the cat CMAH loci were highly associated with the expression of the Neu5Ac on erythrocyte membrane in types B and AB of the feline AB blood group system.

Proliferative and necrotizing otitis externa in a kitten: successful treatment with intralesional and topical corticosteroid therapy

Proliferative and necrotising otitis externa (PNOE) is a very rare disease affecting the ear canals and concave pinnae of kittens. This report describes a 5-month-old cat with PNOE. Histopathological examination confirmed the diagnosis. Treatment was initiated with local injection of methylprednisolone acetate into the lesions. The cat was subsequently treated with clobetasol propionate cream, a potent topical glucocorticoid ointment. The cat showed marked improvement. While topical treatment with tacrolimus, an immunosuppressive agent, is reported to be an effective therapy, to the best of our knowledge, this is the first report to treat PNOE with local corticosteroid therapy.

Measurement of transepidermal water loss (TEWL) in cats with experimental skin barrier dysfunction using a closed chamber system

BACKGROUND

A closed chamber evaporimeter is suitable for measuring transepidermal water loss (TEWL) in cats because of the compact device size, tolerance to sudden movement and short measuring time. TEWL is a representative parameter for skin barrier dysfunction, which is one of the clinical signs of atopic dermatitis in humans and dogs. Measurement of feline TEWL has been reported, but applicability of this parameter has not been validated.

HYPOTHESIS/OBJECTIVES

The aims of this study were to determine if tape stripping is a valid experimental model in cats for studying TEWL and to determine if a closed chambered system is a suitable measurement tool for cats.

ANIMALS

Ten clinically normal cats.

METHODS

In order to evaluate variation of the measured values, TEWL was measured at the right and left side of the three clipped regions (axillae, lateral thigh and groin). Subsequently, TEWL was measured using sequential tape stripping of the stratum corneum as a model of acute barrier disruption.

RESULTS

The variations between both sides of the three regions showed no significant difference. Sequential tape stripping was associated with increasing values for TEWL.

CONCLUSIONS AND CLINICAL IMPORTANCE

Feline TEWL was shown to reflect changes in the skin barrier in an experimental model using a closed chamber system and has the potential for evaluating skin barrier function in cats with skin diseases.

Properties of the feline tumour suppressor reduced expression in immortalized cells (REIC/Dkk-3)

Reduced expression in immortalized cells (REIC/Dkk-3), a member of the human Dickkopf (Dkk) family, is a growth suppressor in human and canine mammary tumours. Mammary gland tumours are common neoplasms with high malignancy in female cats. The purpose of this study was to clone the feline REIC/Dkk-3 homolog, investigate its expression in cell lines established from feline mammary gland tumours, and test its tumour suppressor function. Western blot analysis revealed that expression of the REIC/Dkk-3 protein was reduced in feline mammary carcinoma cell lines. Forced expression of REIC/Dkk-3 induced apoptosis in feline mammary tumour cell lines. These results demonstrate that REIC/Dkk-3 expression, which is downregulated in feline mammary tumour cell lines, results in the induction of apoptosis in these cells. Our findings suggest that feline REIC/Dkk-3 represents a potential molecular target for the development of therapies against feline mammary cancers.

Primary T-cell high-grade lymphoma of the feline uterus

A 12-year-old female American shorthair cat presented with a one-month history of hematuria and general lethargy. Abdominal ultrasonography revealed complete thickening of the left uterine wall. At a diagnostic laparotomy, a large mass arising from the left uterine horn was discovered, and ovariohysterectomy was performed. Histological diagnosis revealed a T-cell high-grade lymphoma of the uterus. After the ovariohysterectomy, the patient achieved complete remission and was maintained by combination chemotherapy from 14 days after surgery. However, relapse occurred in the urinary bladder wall on day 287, and the patient died of postrenal acute renal failure on day 310. This is the first report of a feline case of primary uterine lymphoma that was treated with ovariohysterectomy followed by systemic chemotherapy.

The modified corneocyte surface area measurement as an index of epidermal barrier properties: inverse correlation with transepidermal water loss

BACKGROUND

Corneocyte surface area (CSA) is as established parameter for skin barrier function in humans. Measurement of canine CSA has been previously reported but has not been validated.

HYPOTHESIS/OBJECTIVES

The aim of this study was to evaluate the validity of CSA as a barrier function parameter in dogs.

ANIMALS

Six clinically normal beagle dogs.

METHODS

CSA was measured and compared with transepidermal water loss (TEWL) using sequential tape stripping of the stratum corneum as a model of acute barrier disruption. Then, CSA and TEWL were measured at four anatomical sites (groin, lower back, nasal bridge and pinna). The correlation between the two indices was also evaluated.

RESULTS

From the results of sequential tape stripping, CSA values gradually decreased with increasing number of tape strippings. The CSA values were inversely correlated with the TEWL ones. The two indices at different sites were variable and were strongly correlated.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine CSA was demonstrated to be a useful parameter for the canine skin barrier function. The results from the anatomical sites imply that the cephalic sites (nasal bridge and pinna) were lower than others in skin barrier function.

The canine prostate cancer cell line CHP-1 shows over-expression of the co-chaperone small glutamine-rich tetratricopeptide repeat-containing protein α

Although androgen therapy resistance and poor clinical outcomes are seen in most canine prostate cancer cases, there are only a few tools for analysing canine prostate cancer by using a cell biological approach. Therefore, to evaluate androgen-independent neoplastic cell growth, a new canine prostate cancer cell line (CHP-1) was established in this study. CHP-1 over-expressed the co-chaperone small glutamine-rich tetratricopeptide repeat-containing protein α (SGTA), which is over-expressed in human androgen-independent prostate cancer. The CHP-1 xenograft also showed SGTA over-expression. Although CHP-1 shows poor androgen receptor (AR) signalling upon dihydrotestosterone stimulation, forced expression of AR enabled evaluation of AR signalling. Taken together, these results suggest that CHP-1 will be a useful model for investigating the pathogenesis of androgen-dependent and androgen-independent canine prostate cancer.

Analyses of a satiety factor NUCB2/nesfatin-1; gene expressions and modulation by different dietary components in dogs

Nesfatin-1 is an anorexic peptide derived from a precursor, nucleobindin-2 (NUCB2), which is distributed in various organs, coexists with ghrelin in the gastric X/A-like cells and closely relates to an appetite control in rodents and humans. Nesfatin-1 may be a significant factor addressing the satiety also in veterinary medicine, however, there are few reports about nesfatin-1 in dogs. In the present study, we detected canine NUCB2/nesfatin-1 mRNA in various tissues, especially abundant in pancreas, gastrointestinal tracts, testis and cerebellum. We examined circulating nesfatin-1 concentrations and NUCB2/nesfatin-1 mRNA expressions in upper gastrointestinal tracts (gastric corpus, pyloric antrum and duodenum) in dogs fed on different types of diets. Plasma nesfatin-1 concentrations in the dogs were approximately 4 ng/ml and they did not change after feeding through the study, however, NUCB2/nesfatin-1 mRNA expressions in pyloric antrum were 1.84-fold higher in the dogs fed on a High fiber/High protein diet (P<0.001), 1.48-fold higher in the dogs fed on a High fat/Low protein diet (P<0.05) and 1.02-fold higher in the dogs fed on a Low fat/High carbohydrate diet (not significant) comparing to those on a control diet. It was concluded that High fiber/High protein and High fat/Low protein diets increased NUCB2/nesfatin-1 production in canine gastrointestinal tracts. These results may set the stage for further investigations of canine NUCB2/nesfatin-1, which may relate to satiety effects in dogs.

Genetic variants of the unsaturated fatty acid receptor GPR120 relating to obesity in dogs

G protein-coupled receptor (GPR) 120 is an unsaturated fatty acid receptor, which is associated with various physiological functions. It is reported that the genetic variant of GPR120, p.Arg270His, is detected more in obese people, and this genetic variation functionally relates to obesity in humans. Obesity is a common nutritional disorder also in dogs, but the genetic factors have not ever been identified in dogs. In this study, we investigated the molecular structure of canine GPR120 and searched for candidate genetic variants which may relate to obesity in dogs. Canine GPR120 was highly homologous to those of other species, and seven transmembrane domains and two N-glycosylation sites were conserved. GPR120 mRNA was expressed in lung, jejunum, ileum, colon, hypothalamus, hippocampus, spinal cord, bone marrow, dermis and white adipose tissues in dogs, as those in mice and humans. Genetic variants of GPR120 were explored in client-owned 141 dogs, resulting in that 5 synonymous and 4 non-synonymous variants were found. The variant c.595C>A (p.Pro199Thr) was found in 40 dogs, and the gene frequency was significantly higher in dogs with higher body condition scores, i.e. 0.320 in BCS4–5 dogs, 0.175 in BCS3 dogs and 0.000 in BCS2 dogs. We conclude that c.595C>A (p.Pro199Thr) is a candidate variant relating to obesity, which may be helpful for nutritional management of dogs.

Decreased gene expressions of insulin signal molecules in canine hyperadrenocorticism

Hyperadrenocorticism (HAC) is a common endocrine disorder in dogs, in which excess glucocorticoid causes insulin resistance. Disturbance of insulin action may be caused by multiple factors, including transcriptional modulation of insulin signal molecules which lie downstream of insulin binding to insulin receptors. In this study, gene expressions of insulin signal molecules were examined using neutrophils of the HAC dogs (the untreated dogs and the dogs which had been treated with trilostane). Insulin receptor substrate (IRS)-1, IRS-2, phosphatidylinositol 3-kinase (PI3-K), protein kinase B/Akt kinase (Akt)-2 and protein kinase C (PKC)-lambda were analyzed in the HAC dogs and compared with those from normal dogs. The IRS-1 gene expressions decreased by 37% and 35% of the control dogs in the untreated and treated groups, respectively. The IRS-2 gene expressions decreased by 61% and 72%, the PI3-K gene expressions decreased by 47% and 55%, and the Akt-2 gene expressions decreased by 45% and 56% of the control dogs, similarly. Collectively, gene expressions of insulin signal molecules are suppressed in the HAC dogs, which may partially contribute to the induction of insulin resistance.

Identification of tumor-initiating cells in a canine hepatocellular carcinoma cell line

Tumor-initiating cells (TICs) or cancer stem cells (CSCs), a small subset of tumor cells, are involved in tumor initiation, progression, recurrence and metastasis. In human hepatocellular carcinoma (HCC), TICs are enriched with cell surface markers and have the ability to self-renew and differentiate tumors at a high frequency. We established a canine HCC cell line, HCC930599, and analyzed it for stem and progenitor cell marker expression using flow cytometry. HCC930599 showed high CD44 and CD29, moderate CD90, and low CD133, CD34, CD24, CD117, and CD13 expression. CD90(+)CD44(+) and CD90(-)CD44(+) cells were characterized using the in vitro sphere assay and an in vivo transplant model. CD90(+)CD44(+) cells acquired enhanced self-renewal capacity, proliferative activity and tumourigenicity compared with CD90(-)CD44(+) cells, suggesting that TICs exist in the HCC930599 cell line and that CD90 is a marker for enriched TICs. Understanding TIC characteristics may help elucidate hepatic carcinogenesis and HCC therapy development.

Molecular cloning and tumour suppressor function analysis of canine REIC/Dkk-3 in mammary gland tumours

REIC/Dkk-3, a member of the human Dickkopf (Dkk) family, plays a role as a suppressor of growth in several human cancers. In this study, the tumour suppression function of canine REIC/Dkk-3 was investigated. The full-length open reading frame of the canine REIC/Dkk-3 homologue was cloned and the tissue distribution of REIC/Dkk-3 mRNA was determined, along with the subcellular localisation of the REIC/Dkk-3 protein in canine cancer cell lines. Expression of REIC/Dkk-3 was lower in mammary gland tumours and in canine mammary carcinoma cell lines than in normal mammary gland tissue. Overexpression of REIC/Dkk-3 induced apoptosis in canine mammary carcinoma cell lines. These results show that expression of REIC/Dkk-3 is downregulated in canine mammary tumours and that one of the functions of this gene is induction of apoptosis.

Antitumor effect of bevacizumab in a xenograft model of canine hemangiopericytoma

Canine hemangiopericytoma (CHP) is characterized by frequent local recurrence and increased invasiveness. Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis in tumors. The aim of the present study was to investigate the effect of a single dose of bevacizumab on a xenograft model of CHP. VEGF protein was secreted from cultured CHP cells and interacted with bevacizumab. Bevacizumab treatment suppressed tumor growth by inhibiting tumor angiogenesis, whereas no significant differences were observed in the proliferation index and apoptosis rates of treated and untreated mice. Thus, bevacizumab had antitumor effects in a xenograft model of CHP.

Establishment and characterization of canine rhabdomyosarcoma cell line CMS-C

A novel canine tumor cell line designated as the CMS-C cell line was established from pleomorphic rhabdomyosarcoma (RMS) raised in the prostate gland of a 14-year-old intact male mixed-breed dog. CMS-C cells displayed the same immunohistochemical characteristics (positive for vimentin and desmin and negative for cytokeratin and smooth muscle actin) as the original tumor cells and express myoD1 and UCP3, known as striated muscle-specific molecules, as shown by RT-PCR assay. Therefore, the established CMS-C cell line appears to be of rhabdomyoblast cell origin. The CMS-C cell line established from pleomorphic RMS will be a useful tool for further studies about canine RMS.