Pan-tumour analysis of COX-2 expression in dogs

Cyclooxgenase-2 (COX-2) is associated with inflammatory microenvironment and tumour progression. COX-2 expression was reported in canine tumours, and anti-COX treatment showed therapeutic effects in selected tumour types. Currently, direct comparisons between different tumour types or reports were impossible due to varying evaluation protocols. Additionally, COX-2 expression in relatively uncommon tumours were yet to be evaluated. Here, we analysed COX-2 expression across various tumour types in dogs in a consistent protocol, aiming to revisit accumulated evidence in the field and report novel candidate tumours for anti-COX therapy. COX-2 expression in 32 histological types of tumours, which consisted of 347 samples in total, was investigated using immunohistochemistry followed by the Belshaw's method scoring (range: 0-12). More than the half of the samples expressed COX-2 in mast cell tumours, transitional cell carcinoma in the urinary tract, squamous cell carcinoma, liposarcoma, and melanoma, with COX-2 median scores ranging from 1-8. On the other hand, <20% tissues expressed COX-2 in the half of tumour types investigated. Overall COX-2 positive rate was 27%. In conclusion, the results confirmed COX-2 expression in the well-known COX-2-expresing tumour types and suggested novel candidate tumours for anti-COX-2 therapy. At the same time, overall COX-2 expression was low, and inter- and intra-histology heterogeneity was apparent. This study will provide a foundation reference for future research in canine tumours.

Podoplanin Drives Amoeboid Invasion in Canine and Human Mucosal Melanoma

Mucosal melanoma metastasizes at an early stage of the disease in human and dog. We revealed that overexpression of podoplanin in tumor invasion fronts (IF) was related to poor prognosis of dogs with mucosal melanoma. Moreover, podoplanin expressed in canine mucosal melanoma cells promotes proliferation and aggressive amoeboid invasion by activating Rho-associated kinase (ROCK)-myosin light chain 2 (MLC2) signaling. PDPN-ROCK-MLC2 signaling plays a role in cell-cycle arrest and cellular senescence escape as a mechanism for regulating proliferation. Podoplanin induces amoeboid invasion in the IFs of mouse xenografted tumor tissues, similar to canine mucosal melanoma clinical samples. We further identified that podoplanin expression was related to poor prognosis of human patients with mucosal melanoma, and human mucosal melanoma with podoplanin-high expression enriched gene signatures related to amoeboid invasion, similar to canine mucosal melanoma. Overall, we propose that podoplanin promotes canine and human mucosal melanoma metastasis by inducing aggressive amoeboid invasion and naturally occurring canine mucosal melanoma can be a novel research model for podoplanin expressing human mucosal melanoma.

IMPLICATIONS

Podoplanin could be a new therapeutic target to restrict the metastatic dissemination of canine and human mucosal melanoma.

Co-administration of JQ1, a bromodomain-containing protein 4 inhibitor, enhances the antitumor effect of combretastatin A4, a microtubule inhibitor, while attenuating its cardiotoxicity

Combretastatin A4 (CA4) inhibits microtubule polymerization, and clinical trials of the prodrug, CA4 disodium phosphate (CA4DP), as an anti-cancer agent have been conducted. However, CA4DP has not been marketed to date because the margin between the effective dose and the cardiotoxic dose is insufficient. Meanwhile, bromodomain-containing protein 4 (BRD4) has been reported to be required for recovery from mitotic arrests induced by anti-microtubule drugs. BRD4 has also been reported to be involved in the progression of heart failure. Therefore, we hypothesized that the combined use of CA4DP with BRD4 inhibitors can enhance the antitumor effect and attenuate CA4DP-induced cardiotoxicity. In this study, the antitumor effect and cardiotoxicity caused by the co-administration of CA4DP with JQ1, a BRD4 inhibitor, were evaluated. CA4 or JQ1 alone reduced the viability of cultured canine mammary tumor cells (CHMp-13a). Viability was further reduced by co-administration, through the suppression of c-Myc. BRD4 positivity in CHMp-13a cytoplasm showed a significant increase when treated with CA4 alone, while the increase was not significant following co-administration. In CHMp-13a xenograft-transplanted mice, co-administration of CA4DP and JQ1 suppressed tumor growth significantly. In CA4DP-induced cardiac injury model rats, echocardiography showed a CA4DP-induced decrease in cardiac function and histopathology showed cardiomyocyte necrosis. Meanwhile, these cardiac changes tended to be milder following the co-administration of CA4DP and JQ1. These results suggest that CA4DP-JQ1 co-administration enhances the antitumor effect of CA4DP while attenuating its cardiotoxicity and therefore potentially open the doors to the development of a novel cancer chemotherapy with reduced cardiotoxicity risks.

Expression of podoplanin in various types of feline tumor tissues

Podoplanin is expressed in various human tumors where it promotes tumor progression, epithelial-mesenchymal transition, and distant metastasis. Podoplanin is also expressed in cancer-associated fibroblasts and induces tumor malignancy. The objective of this study was to evaluate podoplanin expression in various types of feline tumor tissues. Immunohistochemical analysis revealed that podoplanin was expressed in cells of 13/15 (87%) squamous cell carcinomas and 5/19 (26%) fibrosarcomas. Moreover, cancer-associated fibroblasts expressed podoplanin in most tumor types, including 18/21 (86%) mammary adenocarcinoma tissues. Our findings demonstrate that various types of feline tumor tissues expressed podoplanin, indicating the importance of the comparative aspects of podoplanin expression, which may be used as a novel research model for podoplanin biology.

Detection of indoleamine 2,3-dioxygenase 1-expressing cells in canine normal and tumor tissues

Cancer immunotherapy is a novel cancer treatment for canine tumors. Indoleamine 2,3-dioxygenase 1 (IDO1) is overexpressed in some human tumors and inhibits antitumor immunity. In this study, we comprehensively evaluated expression pattern of IDO1 and the nature of IDO1-expressing cells in canine normal and tumor tissues. In normal tissue samples, IDO1 expression was detected only in the lymph nodes, spleen, tonsil tissues, and colon tissues. In contrast, IDO1-positive tumor cells were observed in several tumor tissue types. This is the first study to evaluate IDO1 expression in canine normal and tumor tissues, and the results suggest that IDO1 is a promising target for novel cancer immunotherapy in dogs with tumors.

Phase I/II Clinical Trial of the Anti-Podoplanin Monoclonal Antibody Therapy in Dogs with Malignant Melanoma

Podoplanin (PDPN), a small transmembrane mucin-like glycoprotein, is ectopically expressed on tumor cells. PDPN is known to be linked with several aspects of tumor malignancies in certain types of human and canine tumors. Therefore, it is considered to be a novel therapeutic target. Monoclonal antibodies targeting PDPN expressed in human tumor cells showed obvious anti-tumor effects in preclinical studies using mouse models. Previously, we generated a cancer-specific mouse-dog chimeric anti-PDPN antibody, P38Bf, which specifically recognizes PDPN expressed in canine tumor cells. In this study, we investigated the safety and anti-tumor effects of P38Bf in preclinical and clinical trials. P38Bf showed dose-dependent antibody-dependent cellular cytotoxicity against canine malignant melanoma cells. In a preclinical trial with one healthy dog, P38Bf administration did not induce adverse effects over approximately 2 months. In phase I/II clinical trials of three dogs with malignant melanoma, one dog vomited, and all dogs had increased serum levels of C-reactive protein, although all adverse effects were grade 1 or 2. Severe adverse effects leading to withdrawal of the clinical trial were not observed. Furthermore, one dog had stable disease with P38Bf injections. This is the first reported clinical trial of anti-PDPN antibody therapy using spontaneously occurring canine tumor models.

Evaluation of epithelial and mesenchymal cell markers in canine urinary bladder transitional cell carcinoma

Canine transitional cell carcinoma (cTCC) is the most common malignant tumour in the urinary bladder: it is highly invasive and exhibits metastatic characteristics. Inflammation is also strongly related to cTCC. Epithelial tumours often exhibit a mesenchymal cell phenotype during tumour invasion and metastasis owing to epithelial-mesenchymal transition (EMT), which is often induced in chronic inflammation. The aim of this retrospective study was to investigate the expression of epithelial and mesenchymal cell markers in tumour cells and to evaluate its relationship with prognosis of cTCC. In this study, 29 dogs with cTCC who underwent surgical treatment were enrolled. Clinical parameters were reviewed using medical records. Tissue expression of epithelial and mesenchymal markers was evaluated by immunohistochemical analysis. The association between the expression of mesenchymal cell markers and clinical parameters, including prognosis, was statistically examined. In five normal bladder tissues used as controls, no expression of mesenchymal markers was observed, except for one tissue that expressed fibronectin. Conversely, epithelial tumour cells expressed vimentin and fibronectin in 23/29 and 19/28 cTCC tissues, respectively. Regarding clinical parameters, vimentin score in Miniature Dachshunds was significantly higher than those in other dog breeds (P < 0.001). Multivariate survival analyses revealed that age>12 years was related to shorter progression-free survival (P = 0.02). Higher vimentin score, lower fibronectin score, and advanced clinical T stage were significantly correlated with shorter median survival time (P < 0.05). The results of this study indicate that vimentin expression was associated with cTCC progression. Further studies are needed to examine the incidence and relevance of EMT in cTCC.

Aberrant expression of the COX2/PGE2 axis is induced by activation of the RAF/MEK/ERK pathway in BRAFV595E canine urothelial carcinoma

Cancer-promoting inflammation is an important event in cancer development. Canine urothelial carcinoma (cUC) overexpresses prostaglandin E2 (PGE2) and has a unique sensitivity to cyclooxygenase 2 (COX2)-inhibiting therapy. In addition, majority of cUC harbour BRAFV595E mutation. However, mechanisms underlying aberrant PGE2 production in BRAFV595E cUC patients remain unclear. Drug screening revealed that inhibition of RAF/MEK/ERK pathway, p38 and JNK pathway reduced PGE2 production in cUC cells. By pharmacological inhibition of the multiple components in the pathway, activation of the ERK MAPK pathway was shown to mediate overexpression of COX2 and production of PGE2 in BRAFV595E cUC cells. In silico gain-of-function analysis of the BRAF mutation also implicated involvement of mutation in the process. The positive association between ERK activation and COX2 expression was further validated in the clinical patients. Moreover, it was also suggested that p38 and JNK regulates PGE2 production independently of ERK pathway, possibly through COX2-dependent and COX1-/COX2- independent manner, respectively. In conclusion, this study demonstrated that activation of ERK induces production of PGE2 in BRAFV595E cUC cells, which is also independently regulated by p38 and JNK. With its unique vulnerability to COX-targeted therapy, BRAFV595E cUC may serve as a valuable model to study the tumour-promoting inflammation.

Overexpression of human epidermal growth factor receptor 2 in canine primary lung cancer

Human epidermal growth factor receptor 2 (HER2) overexpression has been reported in various human cancers. HER2-targeted therapies showed clinical responses in humans with HER2-positive tumors. The incidence of canine primary lung cancer (cPLC) is increasing, but there are no effective systemic therapies for dogs with late-stage cPLC. HER2-targeted therapy could be an option for cPLC, but HER2 expression in cPLC remains unknown. We evaluated HER2 expression in cPLC. Immunohistochemical analysis revealed that 3 samples (19%) scored 3+; 8 (50%), 2+; 5 (31%); and 1+ and 0 (0%), 0. Of the cPLC tissues, 69% were HER2 positive (scored ≥2+). These data would lead to further evaluation of the role of HER2 in cPLC as a mechanism of malignancy and therapeutic target.

Immunohistochemical evaluation of HER2 expression in canine thyroid carcinoma

The human epidermal growth factor receptor 2 (HER2) is expressed in various human cancers including thyroid cancers (TC) and is used as a diagnostic marker and therapeutic target. Canine TC (cTC), the most common endocrine malignancy in dogs, shows a high metastasis rate, and HER2-targeted therapy could be a candidate for treatment. Here, we immunohistochemically evaluated HER2 expression in 21 paraffin-embedded cTC tissues and scored the degree of expression based on intensity and positivity (score: 0–3+). Four samples (19%) scored 3+; 6 (29%), 2+; 7 (33%), 1+; and 4 (19%), 0. Therefore, 48% of the cTC tissues were HER2 positive (scored ≥2+). These data may lead to further evaluation of the role of HER2 in cTC as a mechanism of malignancy and a therapeutic target.

Detection of human epidermal growth factor receptor 2 overexpression in canine anal sac gland carcinoma

Canine anal sac gland carcinoma (ASGC) frequently occurs in the apocrine glands of the canine anal sac and shows aggressive biological behavior. The expression of human epidermal growth factor receptor 2 (HER2) has been reported in various human and canine tumors. HER2 is a promising therapeutic target of these tumors, and HER2-targeted drugs, such as trastuzumab and lapatinib, have improved the outcome of these patients. In this study, HER2 expression in ASGC was evaluated to investigate its potential as a therapeutic target for canine ASGC. HER2 mRNA expression in surgically resected ASGC tissues was significantly higher than that in normal anal sac tissue. To evaluate the expression of HER2 protein, paraffin-embedded ASGC tissues were immunohistochemically evaluated. Strong and broad staining of HER2 was detected in ASGC tissues, while HER2 was weakly to moderately stained in normal anal sac apocrine glands and squamous epithelia. The degree of HER2 expression in ASGC tissues was scored based on its intensity and positivity (score: 0-3+). Scoring of HER2 expression revealed 6 samples (24%) scored 3+, 14 (56%) scored 2+, and 5 (20%) scored 1+, with no samples scoring 0. In all, 80% of canine ASGC tissues were positive for HER2 (scored ≥2+). Furthermore, putative HER2-overexpressed cells in ASGC were detected with trastuzumab by flow cytometry. These preliminary data may lead to further evaluation of the role of HER2 in canine ASGC as a mechanism of malignancy and as a therapeutic target for HER2-targeted therapy.

Proteolysis of insulin-like growth factor-binding protein-3 is increased in urine from patients with diabetic nephropathy

The insulin-like growth factor (IGF) system has been implicated in the development of experimental diabetic nephropathy. IGF-binding protein-3 (IGFBP-3) modulates IGF actions, and proteolysis decreases its binding affinity for IGFs. The aim of this study was to explore the possibility that proteolysis of IGFBP-3 may be altered in diabetic nephropathy and may therefore modify the intrarenal effects of IGFs. IGFBP-3 proteolysis in urine from diabetic patients with normo- [albumin excretion rate (AER), <20 microg/min], micro- (AER, 20-200 microg/min), and macroalbuminuria (AER, >200 microg/min) was studied in 34 patients with noninsulin-dependent diabetes mellitus (NIDDM), 14 patients with insulin-dependent diabetes mellitus, and 9 controls. Urine samples were analyzed by Western ligand blotting and IGFBP-3 immunoblotting. Protease activity was quantitated using [125I]IGFBP-3 as a substrate. WLB showed three main bands (40-46, 35, and 26 kDa) in control urine and a fainter 18-kDa band. All but the 35-kDa band were immunoreactive with the IGFBP-3 antiserum. The same pattern of IGFBPs was seen in urine from normoalbuminuric diabetic patients. However, the urine of diabetic patients with micro- and macroalbuminuria contained little or no intact 40- to 46-kDa IGFBP-3. In patients with noninsulin-dependent diabetes mellitus, urinary IGFBP-3 protease activity in micro- (n = 13) and macroalbuminuric patients (n = 12; mean +/- SD[SCAP], 75 +/- 25% and 84 +/- 24%) was significantly higher than that in normoalbuminuric patients (29 +/- 9%; P = 0.0001). Similar results were observed in patients with insulin-dependent diabetes mellitus. Proteolytic activity in diabetic urine was due to a serine protease. In conclusion, diabetic nephropathy was associated with IGFBP-3 proteolysis in urine. As similar changes were not observed in patients' sera, this is likely to reflect changes in the kidney or urinary tract, resulting in increased local IGF bioavailability, and therefore may contribute to the structural changes of diabetic nephropathy.

Rapid changes in concentrations of essential elements in organs of rats exposed to methylmercury chloride and mercuric chloride as shown by simultaneous multielemental analysis

An in vivo study of rats given a dominant lethal dose of methylmercury chloride (MMC) or mercuric chloride (HgCl2) was conducted to elucidate the rapid biotransformation of essential elements. The elements were measured by inductively coupled plasma atomic emission spectrometry. For the rat brain Zn concentrations were higher in the MMC group than in the HgCl2 and control groups. The highest Cu concentration was found in HgCl2 dosed rat liver. For the rat kidney the highest Zn concentration was seen in the MMC group. From principal component analysis on the time dependent behaviour of each element in rat organs, characteristics specific to Cu in the liver and kidney and Mn in the brain were found after exposure to HgCl2 and Ca and Zn in the brain after exposure to MMC.

The tissue distribution of 2,3,7,8-chlorine substituted dibenzo-p-dioxins in humans who died of cancer

The tissue distribution of 2,3,7,8-chlorine substituted dibenzo-p-dioxins was conducted in 11 patients who died of cancer. The concentration of octachlorodibenzo-p-dioxin (octa-CDD) was the highest in each organ and tissue and hepta-CDD was also found at relatively high levels, second only to OCDD. The levels of 1,2,3, 7,8-penta-CDD and 1,2,3,6,7,8-hexa-CDD in the spleen were the highest, respectively. 2,3,7,8-Tetra-CDD was also detected and its concentration was the highest in the gonad (0.8-3.2 pg/g-range). From the 2,3,7,8-TCDD toxic equivalent calculations, the highest equivalent value was obtained from a 54-year-old female who died of cancerous goiter. This individual had the highest concentrations of 2,3,7,8-substituted penta- and hexa-CDDs among the 11 patients.

[Effect of mercuric chloride on phospholipid peroxidation in rat]

Individual molecular species of mercuric chloride induced phospholipid peroxide formed in rat brain, liver and kidney were determined using the multi-channel UV-high-performance liquid chromatography (HPLC) combined with potentiometric determination. Mercuric chloride (0.5 mg/kg/day) was administered subcutaneously to rats for 3 days. In accordance with a specified time schedule following administration (0.5, 1, 3 and 5 days), rats were decapitated and the phospholipids of brains, livers and kidneys were extracted and purified. The samples were then injected into the HPLC and the ratio (235 nm/203 nm) of peak area of each phospholipid was calculated. The peroxide value of each sample was determined using the calibration curve of the auto-oxidized standard phospholipids which were analyzed by both potentiometric determination and UV HPLC. Kidney phospholipid peroxides were easier induced than those in other organs reached their maximum peak (20.5 meq./kg) at 1 day after initial administration. Phospholipid peroxides in kidney and brain showed similar movement, while those in liver showed their maximum peak 3 days later. Of the phospholipids, phosphatidylserine and phosphatidylethanolamine seemed to be more susceptible to lipid peroxidation induced by mercuric chloride, the common feature of these two phospholipids being that both of them have primary amine group(s) on their polary heads and both are located on the cytosolic side of cell membrane. These results may be explained by mechanisms that relate to the interaction between mercurials and cell membranes or that between mercurials and primary amine groups of phospholipids. Further study is necessary to clarify the specific mechanisms involved in the induction of lipid peroxidation by mercurials and the interaction of mercurials with phospholipids.

[A report of renal cell carcinoma in a horseshoe kidney]

A case of renal cell carcinoma associated with horseshoe kidney is reported. The patient was a 67 years old man with the chief complaints of dull pain of right upper abdomen. Ultrasonography (US) revealed horseshoe kidney and abnormal mass sign at the right isthmus of the kidney. By the computed tomography (CT) and angiography, renal cell carcinoma associated with horseshoe kidney was diagnosed. Only 18 cases of this rare disease have been reported in Japan. The diagnostic procedures are discussed and the usefulness of selective arteriography of the isthmus is emphasized, as the presentation of vascular anatomy is of great value for diagnosis, surgical treatment and preoperative arterial embolization.

Enhancement of interferon-gamma production in glycyrrhizin-treated human peripheral lymphocytes in response to concanavalin A and to surface antigen of hepatitis B virus

The effects of glycyrrhizin, a component of licorice (Glycyrrhiza glabra) roots, on the production of interferon-gamma in human peripheral lymphocyte-macrophage cultures by concanavalin A (Con A) was examined. Interferon-gamma production in normal lymphocyte-macrophage cultures treated with 10 to 100 micrograms/ml of glycyrrhizin at 37 degrees C for 12 hr or longer, and then treated with 10 micrograms/ml of Con A, was enhanced four to eight times compared to control cell cultures. Lymphocyte-macrophage cultures treated with 10 to 100 micrograms/ml of glycyrrhizin alone did not produce interferon. No significant difference in the adsorption of [3H]Con A to glycyrrhizin-treated and control lymphocyte-macrophage cultures was found, but RNA and protein synthesis of the treated lymphocytes was increased compared to control cells; DNA synthesis, however, was reduced. Collaboration between enriched T-lymphocytes and macrophages, both treated with glycyrrhizin, was needed for the enhancement of interferon-gamma production. A smaller increase in interferon production was also observed in the glycyrrhizin-treated peripheral lymphocyte-macrophage cultures derived from an asymptomatic carrier of hepatitis B virus, in response to Con A and surface antigen of hepatitis B virus.