Effects of aurothiomalate treatment on canine osteosarcoma in a murine xenograft model.

Osteosarcoma is a highly fatal cancer, with most patients ultimately succumbing to metastatic disease. The purpose of this study was to evaluate the effects of the antirheumatoid drug aurothiomalate on canine and human osteosarcoma cells and on canine osteosarcoma growth and metastasis in a mouse xenograft model. We hypothesized that aurothiomalate would decrease osteosarcoma cell survival, tumor cellular proliferation, tumor growth, and metastasis. After performing clonogenic assays, aurothiomalate or a placebo was administered to 54 mice inoculated with canine osteosarcoma. Survival, tumor growth, embolization, metastasis, histopathology, cell proliferation marker Ki67, and apoptosis marker caspase-3 were compared between groups. Statistical analysis was carried out using the Kaplan-Meier method with the log-rank test and one-way analysis of variance with the Tukey's test or Dunn's method. Aurothiomalate caused dose-dependent inhibition of osteosarcoma cell survival (P<0.001) and decreased tumor growth (P<0.001). Pulmonary macrometastasis and Ki67 labeling were reduced with low-dose aurothiomalate (P=0.033 and 0.005, respectively), and tumor emboli and pulmonary micrometastases were decreased with high-dose aurothiomalate (P=0.010 and 0.011, respectively). There was no difference in survival, tumor development, ulceration, mitotic indices, tumor necrosis, nonpulmonary metastases, and caspase-3 labeling. Aurothiomalate treatment inhibited osteosarcoma cell survival and reduced tumor cell proliferation, growth, embolization, and pulmonary metastasis. Given aurothiomalate's established utility in canine and human medicine, our results suggest that this compound may hold promise as an adjunctive therapy for osteosarcoma. Further translational research is warranted to better characterize the dose response of canine and human osteosarcoma to aurothiomalate.

Apoptotic effects of the tyrosine kinase inhibitor, masitinib mesylate, on canine osteosarcoma cells.

Osteosarcoma (OSA) is the most common primary bone tumor in dogs and the guarded prognosis highlights the necessity to find new treatments. Masitinib mesylate is a highly selective tyrosine kinase inhibitor that predominantly targets c-Kit and PDGFR-α/ß. This study evaluated the in-vitro activity of masitinib against three canine OSA cell lines after treatment with increasing concentrations of masitinib (0.1-50 µmol/l) at 24, 48, and 72 h. The IC50 values at 72 h for the three OSA cell lines (POS, HMPOS, and COS31) were determined to be 11.04, 7.09, and 9.74 µmol/l, respectively. In addition, increases in caspase-3/7 activity and transferase dUTP nick end labeling-positive cells indicated apoptotic cell death. Because increased levels of vascular endothelial growth factor are found in dogs with OSA, vascular endothelial growth factor in the supernatant was quantified. Overall, the study found that masitinib causes dose-time dependent OSA cell death in vitro through initiation of caspase-mediated apoptosis, which supports future OSA clinical trials.

Identification of the interleukin-8 (CXCL-8) pathway in feline oral squamous cell carcinoma - A pilot study.

The purpose of this pilot study was to detect the presence of interleukin-8 (IL-8) and the potential downstream effects of IL-8 receptor activation in 2 previously characterized feline oral squamous cell carcinoma cell lines (SCCF1 and SCCF2). Interleukin-8 messenger RNA (mRNA) was initially detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). A previously validated and commercially available enzyme-linked immunosorbent assay (ELISA) test was used to measure IL-8 production in the supernatant of the 2 cell lines. Western blot was used to detect phosphorylation of proteins (AKT, ERK1/2, JAK2, STAT3, and Src), known to be downstream of interleukin-8 receptor activation. The IL-8 receptor-specific antagonists, Reparixin and SCH527123, were used to identify effects on phosphorylation of these proteins. Interleukin-8 mRNA and protein were detected in both SCCF1 and SCCF2 by RT-PCR and ELISA, respectively. Phosphorylation of ERK1/2, STAT3, and Src was detected in both cell lines. Inhibition of the IL-8 receptor led to a decrease in phosphorylation of Src, but not ERK1/2 or STAT3. In conclusion, feline squamous cell carcinoma cell lines can produce IL-8. Phosphorylation of Src seems, at least in part, a consequence of IL-8 receptor activation. The phosphorylation of ERK1/2 and STAT3, although present, seems independent of IL-8 receptor activation. Due to its potential effects on the tumor microenvironment, in addition to its autocrine effects on Src phosphorylation, the inhibition of the IL-8 receptor may become a beneficial therapeutic tool. Evaluation of the presence of both IL-8 and Src in many cases should elucidate their importance.

Le but de cette étude pilote était de détecter la présence d'interleukine-8 (IL-8) et les effets potentiels en aval de l'activation du récepteur IL-8 dans deux lignées cellulaires de carcinome épidermoïde oral félin (SCCF1 et SCCF2) précédemment caractérisées. L'ARN messager de l'interleukine-8 (ARNm) a été initialement détecté par amplification en chaîne par la polymérase à transcription inverse quantitative (qRT-PCR). Un test immuno-enzymatique ELISA précédemment validé et disponible dans le commerce a été utilisé pour mesurer la production d'IL-8 dans le surnageant des deux lignées cellulaires. L'immunobuvardage a été utilisé pour détecter la phosphorylation des protéines (AKT, ERK1/2, JAK2, STAT3 et Src), connues pour être en aval de l'activation du récepteur de l'interleukine-8. Les antagonistes spécifiques du récepteur IL-8, Reparixin et SCH527123, ont été utilisés pour identifier les effets sur la phosphorylation de ces protéines. L'ARNm et la protéine de l'interleukine-8 ont été détectés dans SCCF1 et SCCF2 par RT-PCR et ELISA, respectivement. La phosphorylation de ERK1/2, STAT3 et Src a été détectée dans les deux lignées cellulaires. L'inhibition du récepteur IL-8 a conduit à une diminution de la phosphorylation de Src, mais pas ERK1/2 ou STAT3. En conclusion, les lignées cellulaires de carcinome épidermoïde félin sont capables de produire de l'IL-8. La phosphorylation de Src semble, au moins en partie, une conséquence de l'activation du récepteur IL-8. La phosphorylation de ERK1/2 et STAT3, bien que présente, semble indépendante de l'activation du récepteur IL-8. En raison de ses effets potentiels sur le micro-environnement tumoral, en plus de ses effets autocrines sur la phosphorylation de Src, l'inhibition du récepteur IL-8 peut devenir un outil thérapeutique bénéfique. L'évaluation de la présence à la fois d'IL-8 et de Src dans un grand nombre de cas devrait élucider leur importance.(Traduit par Docteur Serge Messier).

Development of an intramuscular xenograft model of canine osteosarcoma in mice for evaluation of the effects of radiation therapy.

OBJECTIVE: To develop an IM xenograft model of canine osteosarcoma in mice for the purpose of evaluating effects of radiation therapy on tumors. ANIMALS: 27 athymic nude mice. PROCEDURES: Mice were randomly assigned to 1 of 3 groups of 9 mice each: no treatment (control group), radiation at 10 Gy, or radiation at 15 Gy. Each mouse received 5 x 10(5) highly metastasizing parent osteosarcoma cells injected into the left gastrocnemius muscle. Maximum tumor diameter was determined with a metric circles template to generate a tumor growth curve. Conscious mice were restrained in customized plastic jigs allowing local tumor irradiation. The behavior and development of the tumor xenograft were assessed via evaluations of the interval required for tumor-bearing limbs to reach diameters of 8 and 13 mm, extent of tumor vasculature, histomorphology of tumors, degree of tumor necrosis, and existence of pulmonary metastasis and clinical disease in affected mice. RESULTS: Tumor-bearing limbs grew to a diameter of 8 mm (0.2-g tumor mass) in a mean +/- SEM interval of 7.0 +/- 0.2 days in all mice. Interval to grow from 8 to 13 mm was significantly prolonged for both radiation therapy groups, compared with that of the control group. Histologic evaluation revealed the induced tumors were highly vascular and had characteristics consistent with those of osteosarcoma. Pulmonary metastasis was not detected, and there was no significant difference in percentage of tumor necrosis between groups. CONCLUSIONS AND CLINICAL RELEVANCE: A reliable, repeatable, and easily produced IM xenograft model was developed for in vivo assessment of canine osteosarcoma.

Intrinsic radiosensitivity and repair of sublethal radiation-induced damage in canine osteosarcoma cell lines.

OBJECTIVE: To characterize the radiosensitivity and capacity for sublethal damage repair (SLDR) of radiation-induced injury in 4 canine osteosarcoma cell lines. SAMPLE POPULATION: 4 canine osteosarcoma cell lines (HMPOS, POS, COS 31, and D17). PROCEDURES: A clonogenic colony-forming assay was used to evaluate the cell lines' intrinsic radiosensitivities and SLDR capacities. Dose-response curves for the cell lines were generated by fitting the surviving fractions after radiation doses of 0 (control cells), 1, 2, 3, 6, and 9 Gy to a linear quadratic model. To evaluate SLDR, cell lines were exposed to 2 doses of 3 Gy (split-dose experiments) at an interval of 0 (single 6-Gy dose), 2, 4, 6, or 24 hours, after which the surviving fractions were assessed. RESULTS: Mean surviving fraction did not differ significantly among the 4 cell lines at the radiation doses tested. Mean surviving fraction at 2 Gy was high (0.62), and the alpha/beta ratios (predictor of tissue sensitivity to radiation therapy) for the cell lines were low (mean ratio, 3.47). The split-dose experiments revealed a 2.8- to 3.9-fold increase in cell survival when the radiation doses were applied at an interval of 24 hours, compared with cell survival after radiation doses were applied consecutively (0-hour interval). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that these canine osteosarcoma cell lines are fairly radioresistant; alpha/beta ratios were similar to those of nonneoplastic, late-responding tissues. Future clinical investigations should involve increasing the fraction size in a manner that maximizes tumor killing without adverse effects on the nonneoplastic surrounding tissues.

Development and Assessment of a Novel Canine Ex Vivo Corneal Model.

PURPOSE: To develop a novel ex vivo extended culture model of canine corneal epithelial cell wound healing. MATERIALS AND METHODS: Canine corneoscleral rims (CSR) were obtained and, after preparation for culture, were placed on a nutating scaffold and incubated in physiological conditions. In experiment 1, eight CSR in a serum-containing antimicrobial-fortified medium were monitored for epithelial integrity and bacterial infection up to 28 days in culture. CSR were assessed histologically at the end of the culture period end points 0, 7, 14, and 28 days with accompanying scanning electron microscopic (SEM) and transmission electron microscopic (TEM) evaluation. Samples for microbial culture were obtained at days 0, 3, 7, 14, and 28. In experiment 2, uniform 8-mm-diameter superficial corneal epithelial wounds were created and monitored for re-epithelialization in the same culture conditions or in a serum-free protein equivalent medium, with four CSR per group. Standardized digital images were obtained with cobalt filter at the time of fluorescein staining and media change every six hours. Image J imaging software was used to measure the area of fluorescein retention. Re-epithelialization rates were calculated and CSR then fixed for immunohistochemistry (IHC). RESULTS: All corneas survived to end points as described in experiment 1 with no evidence of contamination or compromised epithelial integrity. Histologically, a multilayered epithelium was maintained and corneal edema was not appreciated until day 14. SEM examination revealed epithelial cell layer confluence and migrating epithelial cells of normal cellular morphology with normal cell-cell interactions on TEM. In experiment 2, all eight corneas healed with a healing rate of 0.702 ± 0.130 mm2/h (1.25 mm/day epithelial cell migration rate) and were positive in IHC evaluation for markers of corneal fibrosis. CONCLUSION: This ex vivo canine corneal wound healing model is an appropriate and clinically relevant tool for assessment and modulation of epithelial wound healing.

Comparison of serological tests for the detection of natural heartworm infection in cats.

Serological tests were performed on 380 cats with necropsy-confirmed heartworm disease to compare the performance of currently available commercial laboratory and point-of-care heart-worm serological tests in a heartworm-endemic area. Overall, antigen tests detected 79.3% to 86.2% of heartworm infections and were highly specific. Most cats with false-negative antigen tests had a single male worm. Antibody tests detected 62.1% to 72.4% of heartworm infections and had a wider range of false-positive results (1.4% to 19.1%) than antigen tests (0.3% to 2.0%). Serological tests for feline heartworm infection varied in diagnostic performance. Combining results from antigen and antibody tests achieved greater sensitivity than using either test alone.

Prevalence and risk factors for heartworm infection in cats from northern Florida.

Necropsies were performed on 630 adult cats in northern Florida to determine the prevalence and risk factors for heartworm infection in cats of this region. Heartworms were identified in 4.9% of cats, and serological evidence of heartworm exposure was present in 17% of cats. Not all cats from which heartworms were recovered were seropositive for heartworm antigen or antibody. There was no association between heartworm infection and co-infection with feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV). Male cats were at higher risk of infection with heartworm, FeLV, or FIV than were females. Because even a single heartworm can cause clinical disease or death in cats, the authors conclude that cats in this region should receive heartworm prophylaxis to prevent heartworm infection.

Effect of bevacizumab on angiogenesis and growth of canine osteosarcoma cells xenografted in athymic mice.

Objective-To investigate the effects of bevacizumab, a human monoclonal antibody against vascular endothelial growth factor, on the angiogenesis and growth of canine osteosarcoma cells xenografted in mice. Animals-27 athymic nude mice. Procedures-To each mouse, highly metastasizing parent osteosarcoma cells of canine origin were injected into the left gastrocnemius muscle. Each mouse was then randomly allocated to 1 of 3 treatment groups: high-dose bevacizumab (4 mg/kg, IP), low-dose bevacizumab (2 mg/kg, IP), or control (no treatment). Tumor growth (the number of days required for the tumor to grow from 8 to 13 mm), vasculature, histomorphology, necrosis, and pulmonary metastasis were evaluated. Results-Mice in the high-dose bevacizumab group had significantly delayed tumor growth (mean ± SD, 13.4 ± 3.8 days; range, 9 to 21 days), compared with that for mice in the low-dose bevacizumab group (mean ± SD, 9.4 ± 1.5 days; range, 7 to 11 days) or control group (mean ± SD, 7. 2 ± 1.5 days; range, 4 to 9 days). Mice in the low-dose bevacizumab group also had significantly delayed tumor growth, compared with that for mice in the control group. Conclusions and Clinical Relevance-Results indicated that bevacizumab inhibited growth of canine osteosarcoma cells xenografted in mice, which suggested that vascular endothelial growth factor inhibitors may be clinically useful for the treatment of osteosarcoma in dogs. Impact for Human Medicine-Canine osteosarcoma is used as a research model for human osteosarcoma; therefore, bevacizumab may be clinically beneficial for the treatment of osteosarcoma in humans.