Serum levels of urokinase-type plasminogen activator in healthy dogs and oncologic canine patients

Targeting canine mammary neoplastic epithelial cells with a reengineered anthrax toxin: first study

Mammary tumors are the most frequent type of neoplasms in intact female dogs. New therapies that target neoplastic cells without affecting normal cells are highly sought. The Bacillus anthracis toxin has been reengineered to target tumor cells that express urokinase plasminogen activators and metalloproteinases. In previous studies carried out in our laboratory, the reengineered anthrax toxin had inhibitory effects on canine oral mucosal melanoma and canine osteosarcoma cells. In this study, five canine neoplastic epithelial cell lines (four adenocarcinomas and one adenoma) and one non-neoplastic canine mammary epithelial cell line were treated with different concentrations of reengineered anthrax toxin components. Cell viability was quantified using an MTT assay and half-maximal inhibitory concentration (IC50) values. Cell lines were considered sensitive when the IC50 was lower than 5000 ng/ml. One canine mammary adenocarcinoma cell line and one mammary adenoma cell line showed significantly decreased viability after treatment, whereas the non-neoplastic cell line was resistant. We conclude that the reengineered anthrax toxin may be considered a targeted therapy for canine mammary neoplasms while preserving normal canine mammary epithelial cells.

Prognostic significance of the urokinase plasminogen activator system in tissue and serum of dogs with appendicular osteosarcoma

Urokinase plasminogen activator (uPA) and its receptor uPAR promote cancer invasion and metastasis and are emerging therapeutic targets in both human and canine malignancies. While their clinical significance is well-characterized in multiple human tumor types, studies investigating their roles in osteosarcoma are lacking. The objectives of this study were to characterize serum and tissue uPA/uPAR expression in dogs with osteosarcoma and assess the prognostic significance. Serum samples and a tissue microarray of canine appendicular osteosarcoma were analyzed for uPA and uPAR expression by ELISA (n = 49) and immunohistochemistry (n = 38), respectively. Serum uPA activity was also measured by a chromogenic assay (n = 25). Survival analysis was performed by Kaplan-Meier survival analysis, log rank test, and Cox regression analysis. Serum uPA level was significantly higher in dogs with osteosarcoma than clinically healthy control dogs (median 1905 vs 1440 pg/ml, p = 0.008). The majority of canine osteosarcoma tissues expressed uPA (75.9%) or uPAR (77.6%), with 70.7% dual-positivity, indicating autocrine/paracrine activation of the pathway. Survival analysis revealed shorter progression free survival (PFS) in dogs with high serum uPA level in a discovery cohort (n = 29; median PFS 94 vs 266 days, p = 0.003) but not in a validation cohort (n = 23; median PFS 167 vs 490 days, p = 0.16). The difference was significant when both cohorts were combined (n = 49; median PFS 128 vs 266 days, p = 0.003). Serum uPAR and tissue uPA/uPAR levels were not prognostic. In Cox multivariate analysis, high serum uPA level and activity were both associated with poor prognosis, independent of serum ALP, tumor location, and peripheral lymphocyte/monocyte counts. These results indicate high utilization of the uPA pathway and association with disease progression in canine osteosarcoma. Further study involving prospective evaluation to confirm the prognostic significance is warranted. The high prevalence of tissue uPA and uPAR expression suggests the uPA system as a potential therapeutic target in canine osteosarcoma.

Inhibitory Effects of a Reengineered Anthrax Toxin on Canine and Human Osteosarcoma Cells

Canine and human osteosarcomas (OSA) share similarities. Novel therapies are necessary for these tumours. The Bacillus anthracis toxin was reengineered to target and kill cells with high expressions of matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA). Since canine OSA express MMPs and uPA, we assessed whether the reengineered toxin could show efficacy against these tumours. Two OSA cell lines (canine D17 and human MG63) and a non-neoplastic canine osteoblastic cell line (COBS) were used. Cells were treated with different concentrations of the reengineered anthrax toxin and cell viability was quantified using MTT assay. The cell cycle, apoptosis, and necrosis were analysed by flow cytometry. The wound-healing assay was performed to quantify the migration capacity of treated cells. D17 and MG63 cells had significantly decreased viability after 24 h of treatment. Cell cycle analysis revealed that OSA cells underwent apoptosis when treated with the toxin, whereas COBS cells arrested in the G1 phase. The wound-healing assay showed that D17 and MG63 cells had a significantly reduced migration capacity after treatment. These results point for the first time towards the in vitro inhibitory effects of the reengineered anthrax toxin on OSA cells; this reengineered toxin could be further tested as a new therapy for OSA.

Determination of urokinase-type plasminogen activator serum levels in healthy and oncologic cats

The urokinase plasminogen activator system (uPAS) has been poorly investigated in veterinary oncology. The aim of this study was to determine uPA serum concentrations in healthy and oncologic cats to understand the potential value of uPA as a cancer biomarker. Serum samples were collected from 19 healthy cats and 18 cats with spontaneous malignant neoplasms and uPA was measured through a specific enzyme-linked immunosorbent assay kit. The differences between uPA values and their relation with intrinsic factors and clinicopathological parameters were analyzed using an analysis of variance (ANOVA) and independent t-test. The average serum concentration of uPA in cancerous cats (0.54 ± 0.22 ng/mL) differed from that of healthy cats (1.10 ± 1.16 ng/mL) but was not significantly influenced by cats' clinicopathological parameters or by the presence of metastases. This study describes, for the first time, the serum concentrations of uPA in cats and proposes directions for future studies to uncover the relevance of uPAS in feline carcinogenesis.

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point-of-care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point-of-care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed.