In vitro efficacy of a first-generation valosin-containing protein inhibitor (CB-5083) against canine lymphoma.

Valosin-containing protein (VCP), through its critical role in the maintenance of protein homeostasis, is a promising target for the treatment of several malignancies, including canine lymphoma. CB-5083, a first-in-class VCP inhibitor, exerts cytotoxicity through the induction of irreversible proteotoxic stress and possesses a broad spectrum of anticancer activity. Here, we determined the cytotoxicity CB-5083 in canine lymphoma cells and its mechanism of action in vitro. Canine lymphoma cell lines were treated with varying concentrations of CB-5083 and assessed for viability by trypan blue exclusion and apoptosis by caspase activity assays. The mechanism of CB-5083 action was determined by immunoblotting and RT-qPCR analyses of Lys48 ubiquitination and markers of ER stress (DDIT3), autophagy (SQSTM1, MAP1LC3A) and DNA damage (γH2AX). Unfolded protein response markers were also evaluated by immunoblotting (eIF2α, P-eIF2α) and RT-qPCR (ATF4). CB-5083 treatment resulted in preferential cytotoxicity in canine lymphoma cell lines over control peripheral blood mononuclear cells. CB-5083 rapidly disrupted the ubiquitin-dependent protein degradation system, inducing sustained ER stress as indicated by a dramatic increase in DDIT3. Activation of the unfolded protein response occurred through the increase eIF2α phosphorylation and increased transcription of ATF4, but did not re-establish protein homeostasis. Cells rapidly underwent apoptosis through activation of the caspase cascade. These results further validate VCP as an attractive target for the treatment of canine lymphoma and identify CB-5083 as a novel therapy with clinical potential for this malignancy.

Prospective evaluation of Doppler echocardiography, tissue Doppler imaging and biomarkers measurement for the detection of doxorubicin-induced cardiotoxicity in dogs: A pilot study.

The purpose of this pilot study was to evaluate the usefulness of selected echocardiographic parameters, NT-proBNP and cardiac troponin I (cTnI) in the detection of cardiotoxicity in dogs treated with doxorubicin for various malignancies. Echocardiographic studies and biomarker measurements were performed before each administration of doxorubicin, then 1 and 3 months after completion of therapy. Thirteen dogs were included, with a total cumulative dose of doxorubicin ranging from 30 to 150 mg/m(2). E/A ratio significantly decreased during doxorubicin administration (p=0.047). cTnI level was also significantly affected by treatment (p=0.046), increasing above normal at least at one time point in 11 of 13 dogs. The results of this pilot study suggest that monitoring of left ventricular diastolic function and cTnI level measurement might be useful in the early detection of cardiotoxic signs of doxorubicin therapy in dogs.

Pain induced by a minor medical procedure (bone marrow aspiration) in dogs: comparison of pain scales in a pilot study.

BACKGROUND: Bone marrow aspiration (BMA) is a clinical procedure frequently performed in dogs. OBJECTIVE: To compare levels of pain intensity induced by 3 different BMA procedures using several pain scoring instruments. ANIMALS: Sixteen healthy Beagles. METHODS: A prospective experimental pilot study was conducted using blinded observers. Dogs were randomized into 3 groups: iliac BMA under sedation (Iliac-Sed, n = 4), sternum BMA under sedation (Stern-Sed, n = 4), and sternum BMA on conscious dogs without sedation (Stern-No-Sed, n = 8). RESULTS: Using the SF-Glasgow pain scale, the overall pain score in the Stern-No-Sed group was lower than that in the Stern-Sed group (P = 0.04). Using the 4A-VET pain scale, the effects of procedures over time on pain scores did not differ between and within groups. An inactivity index indicated that the overall score for the Stern-No-Sed group was significantly lower than the scores for the Stern-Sed and Iliac-Sed groups (P ≤ 0.01). There was a significant association in pain assessment using the SF-Glasgow and 4A-VET pain scales (P = 0.0004). When comparing the SF-Glasgowscale to the 4A-VET pain scale, the scores for the Stern-No-Sed group were lower compared to those of the Stern-Sed scores (P = 0.03). Based on telemetered motor activity, the Iliac-Sed group may have experienced more discomfort during the post-procedural period. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs may experience mild to moderate pain after BMA procedures, and the sternal site should be preferred. The SF-Glasgow pain scale showed better interobserver reliability, but the 4A-VET scale was less biased by sedation.

Prospective evaluation of clinically relevant type B hyperlactatemia in dogs with cancer.

BACKGROUND: Cancer is considered a cause of type B hyperlactatemia in dogs. However, studies evaluating cancer as a cause of clinically relevant type B hyperlactatemia (>2.5 mmol/L) are lacking. Cancer cells have a higher lactate production because of increased aerobic glycolysis, known as the "Warburg effect." The mechanisms through which aerobic glycolysis occurs are not well elucidated, but neoplasia may cause type B hyperlactatemia via this process. OBJECTIVES: To determine if malignant tumors of dogs are associated with clinically relevant type B hyperlactatemia (>2.5 mmol/L). ANIMALS: Thirty-seven client-owned dogs with malignant tumors: 22 with hematopoietic and 15 with solid tumors. METHODS: Histology was used to confirm the diagnosis (cytology was considered adequate for diagnosis of lymphoma). Confounding conditions associated with hyperlactatemia were excluded. Lactate measurements were immediately performed on free-flow jugular whole blood samples using the LactatePro analyzer. RESULTS: All dogs had lactate concentrations<2.5 mmol/L. Mean blood lactate concentration was 1.09 mmol/L. Mean blood lactate concentrations for solid and hematopoietic tumors were 0.95 and 1.19 mmol/L, respectively. Dogs with lymphoma (n=18) had a mean blood lactate concentration of 1.15 mmol/L. CONCLUSIONS: Malignant tumors were not considered a cause of clinically relevant type B hyperlactatemia. Therefore, cancer-related type B hyperlactatemia in dogs is uncommon, and hyperlactatemia should prompt careful investigation for causes other than cancer.