Kohji Maruo

We analyzed the status of tumor development in dogs by breed based on tumor cases that presented to the Department of Veterinary Pathology of the Gifu University for diagnostic examinations over eight years (2005-2012). We also calculated the crude incidence of tumors in dogs by breed based on the results of a survey conducted in 2011 in Gifu Prefecture. The most common sites of tumor development included the skin, digestive organs and mammary glands. Smaller dogs showed a tendency to have a higher incidence of breast tumors. We thus identified dog breeds with a higher crude incidence of tumors (Bernese mountain dog, golden retriever, corgi, etc.) and those with a lower crude incidence of tumors (Pomeranian, poodle, Chihuahua, etc.). Unlike the current trends for domestic dogs in the US and Europe, Japan has a higher number of small dogs as pets; it is therefore necessary to develop a policy for canine cancer specific to Japan.

Malignant endothelial proliferative diseases including human angiosarcoma (AS) and canine hemangiosarcoma (HSA) are serious diseases with a grave prognosis. Establishing liquid biopsy-based biomarkers for screening has definite clinical utility; however, plasma miRNAs up- or down-regulated in these sarcomas have been unclear. For identifying possible diagnostic plasma miRNAs for these sarcomas, we investigated whether plasma miR-214 and miR-126, which miRNAs play important roles in angiogenesis and tumorigenesis, were elevated in malignant endothelial proliferative diseases. For this investigation, human angiosarcoma and canine hemangiosarcoma cell lines and clinical plasma samples of canine hemangiosarcoma were examined by performing miRNA qRT-PCR. We report here that human angiosarcoma and canine hemangiosarcoma cell lines over-secreted miR-214 and miR-126 via microvesicles; in addition, their levels in the plasma samples from canines with hemangiosarcoma were increased. Moreover, the surgical resection of primary tumors decreased the levels of plasma miR-214 and miR-126. Our findings suggest that these malignant endothelial proliferative diseases over-secreted miR-214 and miR-126, thus suggesting that these miRNAs have potential as diagnostic biomarkers for malignant endothelial proliferative diseases in canine and possible in human angiosarcoma.

Radioresistance of cats has been seen in animal radiotherapy. Feline radioresistance and its underlying mechanism(s) were investigated in fibroblast cells and lymphocytes. We hypothesized that radioresistance was attributable to an increase in the cells ability to repair DNA damage. To investigate this hypothesis, fibroblast cells were exposed to various doses of X rays and then colony formation assays were performed. Survival curves showed that potential lethal damage repair (PLDR) for feline cells were greater than that for human cells. γ-H2AX foci assays were performed to evaluate DNA double-strand breaks (DSBs) formation and repair kinetics. After PLDR, feline cells displayed a decreased residual amount of γ-H2AX foci. Formation of chromosome aberrations (dicentrics) after PLDR as an indicator of radiation-induced DNA damage and repair; human, feline and canine lymphocytes were evaluated. Human and canine lymphocytes showed two to three times the number of dicentrics compared to feline lymphocytes. Fi...

3歳2カ月齢，未避妊雌のゴールデンレトリーバーが，左前腕遠位部腫瘤の増大を主訴に来院した．X線検査にて腫瘤は高度に石灰化しており骨様の陰影を示した．細針生検にて骨軟骨系腫瘍が疑われると診断されたため，治療を兼ねた切除生検を行った．腫瘤は橈骨と尺骨の間に入り込み，完全切除はできなかった．摘出した腫瘤は病理組織学的検査にて骨軟骨腫と診断された．術後16カ月経過しているが，残存した組織の増大は認められず，良好な経過をたどっている．

Background: Human hemangiosarcoma (HSA) tends to have a poor prognosis; its tumorigenesis has not been elucidated, as there is a dearth of HSA clinical specimens and no experimental model for HSA. However, the incidence of spontaneous HSA is relatively high in canines; therefore, canine HSA has been useful in the study of human HSA. Recently, the production of angiogenic growth factors and their receptors in human and canine HSA has been reported. Moreover, the growth-factor environment of HSA is very similar to that of pathophysiological angiogenesis, which some homeobox genes regulate in the transcription of angiogenic molecules. In the present study, we established 6 xenograft canine HSA tumors and detected the expression of growth factors, their receptors, and angiogenic homeobox genes. Methods: Six primary canine HSAs were xenografted to nude mice subcutaneously and serially transplanted. Subsequently, the expressions of vascular endothelial growth factor (VEGF)-A, basic fibroblast growth factors (bFGF), flt-1 and flk-1 (receptors of VEGF-A), FGFR-1, and angiogenic homeobox genes HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 were investigated in original and xenograft tumors by histopathology, immunostaining, and reverse transcription polymerase chain reaction (RT-PCR), using canine-specific primer sets. Results: Histopathologically, xenograft tumors comprised a proliferation of neoplastic cells that were varied in shape, from spindle-shaped and polygonal to ovoid; some vascular-like structures and vascular clefts of channels were observed, similar to those in the original tumors. The expression of endothelial markers (CD31 and vWF) was detected in xenograft tumors by immunohistochemistry and RT-PCR. Moreover, the expression of VEGF-A, bFGF, flt-1, flk-1, FGFR-1, HoxA9, HoxB3, HoxB7, HoxD3, Pbx1, and Meis1 was detected in xenograft tumors. Interestingly, expressions of bFGF tended to be higher in 3 of the xenograft HSA tumors than in the other tumors. Conclusion: We established 6 xenograft canine HSA tumors in nude mice and found that the expressions of angiogenic growth factors and their receptors in xenograft HSAs were similar to those in spontaneous HSA. Furthermore, we detected the expression of angiogenic homeobox genes; therefore, xenograft models may be useful in analyzing malignant growth in HSA.

9歳，未避妊雌の柴犬が他院で前胸部腫瘤を指摘され，精査のため来院した．X線検査で腹部にも巨大な腫瘤が認められ，病理学的検査で未分化胚細胞腫およびその胸骨リンパ節への転移が疑われた． シスプラチンによる化学療法および放射線治療を行ったところ腹部，胸部の腫瘤が著しく縮小し，外科的に摘出することが可能となった． 摘出後，エトポシドによる術後補助化学療法を行った． しかし副作用が見られ投薬を中止した． 手術から現在まで約7カ月間再発等は認められていない．

卵巣子宮摘出術および去勢手術後の病理組織検査で，生殖器系腫瘍と診断され，転移が認められたあるいはその危険があった犬3例が，術後化学療法のために来院した．各症例の診断名は，腹膜播種を伴う卵巣腺癌，脈管浸潤を伴う顆粒膜細胞腫，腹腔内リンパ節転移を伴うセミノーマであった．3症例に対しシスプラチン40～50mg/m² を3週間おきに4回ないし5回腹腔内に投与したところ，2例に関しては現在までそれぞれ術後約31カ月および7カ月間転移は認められていない．リンパ節転移が認められた1例に関しては初診時に56.4×26.5mm であった下腹リンパ節が5回投与後に45.7×17.9mm まで縮小した．

Gastrointestinal stromal tumors (GISTs) of cecum (case 1) and pylorus (case 2) were surgically removed and diagnosed in two dogs. Case 1 was clinically normal 10 months after surgery, whereas case 2 died of intraperitoneal metastasis 55 days after the operation. The percentage of cells that were Ki-67 positive were 4.4%(case 1) and 19.2%(case 2), and the mitosis index was 0.25% and 1.1%, respectively. The fact that case 1 had a favorable outcome while case 2 had a very poor result may suggest that canine GISTs have various outcomes. Ki-67 and mitosis index may be good prognostic factors for canine GISTs.