Activation of the Akt signalling pathway as a prognostic indicator in canine soft tissue sarcoma

Canine soft tissue sarcoma (STS) is relatively common in dogs and is the generic term for tumours that originate from mesenchymal cells. While histopathological grade and immunolabelling with Ki-67 have been used for estimating prognosis, additional indicators are needed for predicting prognosis. Aberrant cell signalling pathways may contribute to disease activity and, therefore, prognostic markers. However, their role in canine STS remains poorly understood. The aim of this study was to investigate expression of phosphorylated Akt (phospho-Akt) and phosphorylated S6 (phospho-S6) as potential prognostic indicators. Immunohistochemical labelling was conducted on clinical samples of canine STS (n = 67). We found that phospho-Akt expression was positively correlated with histopathological grade (P = 0.001) and Ki-67 index (P <0.01). There was no apparent relationship between the type of STS and the expression of phospho-Akt. The number of cases that expressed phospho-S6, which is the downstream molecule of the Akt signalling pathway, was higher in immunopositive phospho-Akt cases than in immunonegative phospho-Akt cases (P <0.0001). Furthermore, phospho-Akt expression was significantly higher in recurrent and metastatic cases. We also confirmed that phosphorylation of Akt occurred in conjunction with S6 phosphorylation in three canine STS cell lines. These results suggest that immunolabelling for phospho-Akt, phospho-S6 and Ki-67 could potentially be used as a prognostic indicator and therapeutic target in canine STS.

Outcome of a dog with urinary bladder osteosarcoma treated with a total cystectomy and ureterocutaneostomy

A 10-year-old, neutered female, French bulldog was presented with a history of dysuria, hematuria, stranguria, and pollakiuria. Diagnostic tests revealed a large mass at the neck of the bladder without any evidence of metastatic disease. Total cystectomy with bilateral cutaneous ureterostomy creation was elected. Histopathology of the bladder mass revealed extraskeletal osteosarcoma, which was resected completely. Neither recurrence nor metastasis had been detected as of 65 months after surgery. Extraskeletal osteosarcomas are typically malignant and carry a poor prognosis. This is the first report of bladder osteosarcoma in a dog treated by total cystectomy and ureterocutaneostomy with excellent long-term control.

Mismatch repair deficiency in canine neoplasms

The DNA mismatch repair (MMR) system preserves genomic stability by identifying and repairing mismatched nucleotides in the DNA replication process. The dysfunction of the MMR system, also known as mismatch repair deficiency (dMMR), is implicated as a predictive biomarker for the efficacy of immune checkpoint blockade therapy regardless of the tumor type in humans. This study aimed to evaluate the immunolabeling of MMR proteins in canine tumors and to identify the types of tumors having dMMR. First, we performed immunohistochemistry in 8 different canine tumors (oral malignant melanoma, high-to-intermediate grade lymphoma, mast cell tumor, malignant mammary gland tumor, urothelial carcinoma, hepatocellular carcinoma, osteosarcoma, and hemangiosarcoma) with 15 samples each to analyze the immunolabeling of canine mismatch repair proteins (MSH2, MSH6, and MLH1) using anti-human monoclonal antibodies. We found that more than half of canine oral malignant melanoma (60%) and hepatocellular carcinoma (53%) samples and fewer of the other canine tumors had loss of immunolabeling in ≥1 MMR protein (ie, evidence of defective MMR proteins, based on the definition of dMMR in the humans). Antibodies against human MSH2, MSH6, and MLH1 were cross-reactive with the corresponding canine protein as confirmed using MMR gene knockout canine cell lines. Further studies are required to investigate the clinical outcomes in canine spontaneous tumors with dMMR to determine the potential for immune checkpoint blockade therapy for these tumor types.

Naturally occurring neoplasms in pigeons in a research colony: a retrospective study

This study reports the gross and microscopic pathology of naturally occurring neoplasms in adult pigeons that were presented for necropsy at the Indiana Animal Disease Diagnostic Laboratory from 2001 to 2011. The study population consisted of white carneau and mixed-breed pigeons used in behavioral studies in the Department of Psychological Sciences at Purdue University. Twelve types of neoplasms or proliferative disorders were identified in 28 of 83 pigeons (33.7%). Five pigeons had two or three types of neoplasms-proliferative disorders. Of the 83 pigeons, 11 (13.3%) had seminoma, five (6.0%) had thyroid adenoma, four (4.8%) had lymphoma, four (4.8%) had adenocarcinoma of female reproductive tract origin, two (2.4%) had pulmonary carcinoma, and two (2.4%) had cutaneous vascular hamartomas. Also identified were single incidences of dysgerminoma, mesothelioma, liposarcoma, cloacal papilloma, cloacal adenocarcinoma, and gizzard carcinoma. The most frequently occurring tumor was seminoma; 7/11 cases effaced both testicles and 3/11 cases had metastasis to the liver or kidney. The relatively high prevalence of neoplasms in pigeons in the present study is most likely related to the advanced ages of pigeons kept in the research colony.

ImmunoAT method: An initial assessment for the detection of abnormal isoforms of prion protein in formalin-fixed and paraffin-embedded tissues

The AT-tailing method is a labelling technique that utilises oligo(dA-dT)-dependent signal amplification. In this study, a new immunohistochemical application of the immunoAT method was developed. This method uses an oligo(dA-dT)-conjugated primary antibody (direct immunoAT method) or an oligo(dA-dT)-conjugated secondary antibody (indirect immunoAT method). Fifteen-base oligo(dA-dT)-conjugated antibodies (IgG-ATs) were prepared in advance by conjugating maleimide-activated oligo(dA-dT) to IgG via free sulfhydryl residues that had been introduced on the surface of IgG using Traut's reagent. Following the reaction with the target antigen and the IgG-AT, oligo(dA-dT) was elongated by DeltaTth DNA polymerase in the presence of dATP, dTTP and biotinylated dUTP, consequently labelling the antigen-antibody complex with a large amount of biotin. To initially evaluate the immunoAT method, the presence or absence of prion protein (PrP(sc)) was determined in formalin-fixed and paraffin-embedded sections of the medulla oblongata of cattle which had been under active surveillance for bovine spongiform encephalopathy. Sections were examined using direct and indirect immunoAT methods and the EnVision+ system (Dako) under conditions that were identical except for the differing IgG-AT and AT-tailing methods. PrP(sc) detection was consistent using all three methods. The clearest signals were obtained using the indirect immunoAT method, suggesting significant potential for this method.

Nuclear localization of Merkel cell polyomavirus large T antigen in Merkel cell carcinoma

To clarify whether mutations in the large T gene encoded by Merkel cell polyomavirus affect the expression and function of large T antigen in Merkel cell carcinoma cases, we investigated the expression of large T antigen in vitro and in vivo. Immunohistochemistry using a rabbit polyclonal antibody revealed that large T antigen was expressed in the nuclei of Merkel cell carcinoma cells with Merkel cell polyomavirus infection. Deletion mutant analyses identified an Arg-Lys-Arg-Lys sequence (amino acids 277-280) as a nuclear localization signal in large T antigen. Sequence analyses revealed that there were no mutations in the nuclear localization signal in any of the eleven Merkel cell polyomavirus strains examined. Furthermore, stop codons were not observed in the upstream of the nuclear localization signal in any of the Merkel cell carcinoma cases examined. These data suggest that the nuclear localization signal is highly conserved and functional in Merkel cell carcinoma cases.