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- Author or Editor: Michael S. Kent x
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Abstract
Objective—To investigate activation of the mammalian target of rapamycin (mTOR) pathway and the antitumor effect of rapamycin in canine osteosarcoma cells.
Sample Population—3 established primary canine osteosarcoma cell lines generated from naturally developing tumors.
Procedures—Expression of total and phosphorylated mTOR and p70S6 kinase was assessed by use of western blot analysis in canine osteosarcoma cells with and without the addition of rapamycin. A clonogenic assay was performed to determine the surviving fraction of osteosarcoma cells at various concentrations of rapamycin.
Results—Total and phosphorylated mTOR and p70S6 kinase expression was evident in all 3 cell lines evaluated, which was indicative of activation of this pathway. Treatment with rapamycin resulted in a time-dependent decrease in phosphorylated mTOR expression and a lack of detectable phosphorylated p70S6 kinase. No detectable change in expression of total mTOR and total p70S6 kinase was identified after rapamycin treatment. The clonogenic assay revealed a significant dose-dependent decrease in the surviving fraction for all 3 cell lines when treated with rapamycin.
Conclusions and Clinical Relevance—These data indicated that mTOR and its downstream product are present and active in canine osteosarcoma cells. The pathway can be inhibited by rapamycin, and treatment of cells with rapamycin decreased the surviving tumor cell fraction. These data support the molecular basis for further investigation into the use of mTOR inhibitors as an antineoplastic approach for dogs with osteosarcoma.
Abstract
Objective—To investigate the activation of the AKT and mammalian target of rapamycin (mTOR) pathways and assess the inhibitory effects of rapamycin on those pathways in canine malignant melanoma cells.
Sample Population—3 established primary canine melanoma cell lines generated from naturally occurring tumors.
Procedures—Expressions of total and phosphorylated AKT, mTOR, and p70 ribosomal S6 kinase 1 (p70S6K) in canine melanoma cells that were or were not exposed to 10nM rapamycin were assessed via western blot analysis. Clonogenic assays were performed to determine the surviving fraction of melanoma cells after exposure to 0.1, 1, 10, or 100nM rapamycin.
Results—Expressions of total and phosphorylated AKT, mTOR, and p70S6K proteins were detected (ie, the AKT and mTOR pathways were activated) in all 3 cell lines. Rapamycin treatment resulted in decreases in phosphorylated mTOR expression and phosphorylated p70S6K expression but no change in phosphorylated AKT expression. Expression of total AKT, mTOR, and p70S6K persisted after rapamycin treatment. There was a significant dose-dependent decrease in surviving tumor cell fraction for each cell line following treatment with rapamycin.
Conclusions and Clinical Relevance—These data indicated that AKT and mTOR, as well as their downstream product p70S6K, are present and active in canine melanoma cells. Activation of the mTOR pathway can be inhibited by rapamycin; treatment of melanoma cells with rapamycin decreased the surviving tumor cell fraction. Use of mTOR inhibitors as antineoplastic treatments in dogs with melanoma warrants investigation. Furthermore, these data support the use of canine melanoma cells as a molecular model for melanoma in humans.
Abstract
Objective—To determine expression of microRNA (miRNA) in urinary bladder samples obtained from dogs with grossly normal urinary bladders, inflammatory bladder disease, or transitional cell carcinoma (TCC) and in cells of established canine TCC cell lines.
Sample—Samples of grossly normal bladders (n = 4) and bladders from dogs with inflammatory bladder disease (13) or TCC (18), and cells of 5 established canine TCC cell lines.
Procedures—Expression of 5 miRNAs (miR-34a, let-7c, miR-16, miR-103b, and miR-106b) that target p53, Rb, or Bcl-2 protein pathways was determined for bladder samples and cells via quantitative real-time PCR assay. Effects of cisplatin (5μM) on proliferation and miRNA expression of cells were determined.
Results—Expression of miR-34a and miR-106b was significantly higher in TCC samples than it was in samples of grossly normal bladders. Expression of miR-34a, miR-16, miR-103b, and miR-106b was higher in TCC samples than it was in bladder samples from dogs with inflammatory bladder disease. Cells of established canine TCC cell lines that had the lowest growth after cisplatin treatment had increased miR-34a expression after such treatment.
Conclusions and Clinical Relevance—Findings of this study indicated results of miRNA expression assays can be used to distinguish between samples of grossly normal bladders and bladders of dogs with inflammatory bladder disease or TCC. This finding may have clinical relevance because currently available diagnostic tests cannot be used to differentiate these tissues, and inflammatory bladder disease and TCC are both prevalent in dogs. Validation of miRNA expression assays as diagnostic tests may be warranted.
Abstract
Objective—To determine progression-free and overall survival times of cats with squamous cell carcinoma (SCC) of the nasal planum following treatment with a single fraction of strontium Sr 90 (90Sr).
Design—Retrospective case series.
Animals—49 cats with SCC of the nasal planum.
Procedures—Information including FIV infection status, diagnosis of SCC vs SCC in situ (ie, evidence that the tumor did or did not penetrate the epidermal basement membrane, respectively), 90Sr dose and number of probe applications, treatment-related response and complications, and recurrence of SCC and new lesion development was obtained from medical records. The relationships of these variables with calculated progression-free and overall survival times were assessed.
Results—Of 49 cats that underwent 90Sr plesiotherapy (median dose, 128 Gy), 48 (98%) had a response to treatment and 43 (88%) had a complete response. Median progression-free and overall survival times were 1,710 and 3,076 days, respectively. Treatment complications were infrequent (4 [8%] cats) and mild. Following treatment, the SCC recurrence rate was 20% (10/49 cats); 16 (33%) cats developed new lesions in other locations. Overall survival time was significantly longer for cats with a complete response to treatment than for those with a partial response. None of the other variables evaluated had a significant effect on progression-free or overall survival time.
Conclusions and Clinical Relevance—Treatment of cats with SCC of the nasal planum with a single fraction of 90Sr appeared to be effective and well tolerated. Initial response to treatment was predictive of overall survival time.
Abstract
OBJECTIVE To determine the incidence of chyloabdomen diagnosis in cats and dogs and characterize and compare between species the corresponding clinical signs, clinicopathologic test results, and outcomes.
DESIGN Retrospective case series.
ANIMALS 36 cats and 17 dogs in which chyloabdomen was diagnosed at a veterinary teaching hospital between 1984 and 2014.
PROCEDURES Medical records were reviewed, and data retrieved included patient signalment; clinical signs at initial evaluation; results of physical examination, diagnostic tests, and imaging studies; and outcomes. Survival analyses, descriptive statistics, and comparisons between species were completed.
RESULTS The incidence of chyloabdomen at the veterinary teaching hospital during the study period was 2.0 cases/100,000 admissions for cats and 2.8 cases/100,000 admissions for dogs. The mean age at diagnosis of chyloabdomen in cats was 11.3 years, compared with 6.9 years in dogs. The most common clinical signs in dogs and cats combined were lethargy (39/51 [76%]) and anorexia (37/51 [73%]), but fewer (23/53 [43%]) had abdominal distention. Chylothorax was a common comorbidity (25/53 [47%]), with malignant neoplasia being the most common underlying diagnosis (24/53 [45%]). Survival analyses included 44 patients; median survival time from diagnosis of chyloabdomen was 31 days overall, 8 days for patients with malignant neoplasia, and 73 days for patients without neoplasia.
CONCLUSIONS AND CLINICAL RELEVANCE There were multiple causes of chyloabdomen in dogs and cats of the study, and outcome depended on underlying cause. Because of this and the rarity of chyloabdomen, a multicenter prospective study of disease progression, treatment response, and clinical outcome for dogs and cats with chyloabdomen is needed.
Abstract
Objective—To determine whether there was a decline in the percentage of dogs undergoing necropsies and whether there was substantial agreement or disagreement between clinical and pathologic diagnoses.
Design—Retrospective study.
Animals—623 dogs.
Procedure—Medical records of hospitalized dogs that died or were euthanatized and necropsied at a veterinary teaching hospital in 1989 and 1999 were reviewed. Clinical and pathologic diagnoses were recorded and compared.
Results—There was a significant decline in the necropsy rate of hospitalized dogs that died or were euthanatized in 1999, compared with 1989. In both 1989 and 1999, there was disagreement between the clinical and pathologic diagnoses in approximately a third of the cases.
Conclusions and Clinical Relevance—Despite improved diagnostic methods, the accuracy of diagnosis did not improve significantly in 1999, compared with 1989. Necropsy is the best method to assess overall diagnostic accuracy. Increased availability of teaching funds may promote efforts to have necropsies performed in veterinary teaching hospitals. ( J Am Vet Med Assoc 2004;224:403–406)
Abstract
OBJECTIVE
To describe radiotherapy outcomes for canine infiltrative lipomas and provide detailed radiotherapy planning data.
ANIMALS
24 dogs from 2000 to 2020.
METHODS
In this retrospective study, dogs received 1 to 3 surgeries prior to conventionally fractionated radiotherapy for gross (18) or microscopic (8) infiltrative lipomas. Dogs received 45 to 51 Gray (Gy) in 15 to 20 daily fractions, with 71% of dogs receiving 48 Gy in daily 3-Gy fractions.
RESULTS
Masses were regionally located as follows: limbs (7), trunk (13), head/neck (4). At analysis, 16/24 dogs were deceased, 5/24 were alive (median follow-up for alive dogs: 1,216 days [range, 741 to 1,870 days]), and 3/24 were lost to follow-up. One living dog had progressive disease 923 days after completing conventionally fractionated radiotherapy and received another surgery. The estimated median overall survival (OS) after completing radiotherapy was 4.8 years (1,760 days; 95% CI, 1,215 to 2,777 days; range, 23 to 3,499 days) for any cause of death, and no patients were reported to have been euthanized or died from their tumor. No statistically significant difference was found for dogs based on gross versus microscopic disease (gross OS, 4.8 years vs microscopic OS, 3.6 years; P = .45). Furthermore, the number of surgeries before radiotherapy did not impact survival (P = .96). The survival difference between females (median OS, 7.6 years; 95% CI, 963 days to not reached) versus males (median OS, 4.6 years; 95% CI, 335 to 2,245 days; P = .05) was statistically significant, although 4/5 living dogs were female.
CLINICAL RELEVANCE
This study demonstrates lengthy survivals with radiotherapy, even with gross disease, for dogs with infiltrative lipomas.
Abstract
Objective—To develop a computer-assisted image analysis procedure for quantitation of neovascularization in formalin-fixed paraffin-embedded specimens of thyroid gland tissue from dogs with and without thyroid gland neoplasia.
Sample Population—47 thyroid gland carcinomas, 8 thyroid gland adenomas, and 8 specimens of thyroid tissue from dogs without thyroid gland abnormalities (normal).
Procedure—Serial tissue sections were prepared and stained with antibodies against human CD31 or factor VIII-related antigen (factor VIII-rag). The areas of highest vascularity were identified in CD31- stained sections, and corresponding areas were then identified in factor VIII-rag-stained sections. Image analysis was used to calculate the total vascular density in each section, and neovascularization, expressed as a percentage, was determined as the absolute value of the total vascular density derived from factor VIII-rag-stained sections minus the vascular density derived from CD31-stained sections.
Results—Mean vascular density of thyroid gland carcinomas derived from CD31-stained sections was significantly greater than density derived from factor VIII-rag-stained sections. This incremental difference was presumed to represent degree of neovascularization. However, significant differences were not detected between vascular densities derived from CD31 and factor VIII-rag-stained sections for either normal thyroid gland tissue or thyroid gland adenomas. No significant correlations were found between vascular density in thyroid gland carcinomas and survival time following surgery.
Conclusion and Clinical Relevance—A computerassisted image analysis method was developed for quantifying neovascularization in thyroid gland tumors of dogs. This method may allow identification of dogs with tumors that are most likely to respond to treatment with novel antiangiogenesis agents. (Am J Vet Res 2002;63:363–369)
Abstract
Objective—To optimize the use of CT-guided modeling for the calculation of body surface area (BSA) in domestic rabbits (Oryctolagus cuniculus).
Animals—12 domestic rabbits.
Procedures—Adult rabbits (body weight, 1 to > 4 kg) that were client-owned animals undergoing CT for disease diagnosis or deceased laboratory animals donated from other research projects were scanned with a CT scanner. Images were transferred to a radiation therapy planning software program. Image slices were captured as contiguous slices at 100 kVp and 100 mA and processed to 0.1-cm-thick sections. The length of each contoured slice was summed to calculate a final BSA measurement. Nonlinear regression analysis was then used to derive an equation for the calculation of BSA in rabbits.
Results—The constant calculated by use of this method was 9.9 (range, 9.59 to 10). The R 2 for the goodness of fit was 0.9332. The equation that best described BSA as a function of body weight for domestic rabbits with this method was as follows: BSA = (9.9 × [body weight {in grams}]2/3)/10,000.
Conclusions and Clinical Relevance—The BSA calculated via the CT-guided method yielded results similar to those obtained with equations for other similarly sized mammals and verified the use of such equations for rabbits. Additionally, this technique can be used for species that lack equations for the accurate calculation of BSA.
Abstract
Objective—To compare associations between vaccine types and other injectable drugs with development of injection-site sarcomas in cats.
Design—Case-control study.
Animals—181 cats with soft tissue sarcomas (cases), 96 cats with tumors at non-vaccine regions (control group I), and 159 cats with basal cell tumors (control group II).
Procedures—Subjects were prospectively obtained from a large pathology database. Demographic, sarcoma location, basal cell tumor, and vaccine and other injectable history data were documented by use of a questionnaire and used to define case, control, and exposure status. Three control groups were included: cats with sarcomas at non-vaccine sites, cats with basal cell tumors, and a combined group of cats with sarcomas at non-vaccine sites and cats with basal cell tumors. χ2 tests, marginal homogeneity tests, and exact logistic regression were performed.
Results—In the broad interscapular region, the frequency of administration of long-acting corticosteroid injections (dexamethasone, methylprednisolone, and triamcinolone) was significantly higher in cases than in controls. In the broad rear limb region, case cats were significantly less likely to have received recombinant vaccines than inactivated vaccines; ORs from logistic regression analyses equaled 0.1, with 95% confidence intervals ranging from 0 to 0.4 and 0 to 0.7, depending on control group and time period of exposure used.
Conclusions and Clinical Relevance—This case-control study measuring temporal and spatial exposures efficiently detected associations between administrations of various types of vaccines (recombinant vs inactivated rabies) and other injectable products (ie, long-acting corticosteroids) with sarcoma development without the need to directly measure incidence. These findings nevertheless also indicated that no vaccines were risk free. The study is informative in allowing practitioners to weigh the relative merits and risks of commonly used pharmaceutical products.
