Detection of progressive and regressive phase and LINE-1 retrotransposon in transfected dogs with transmissible venereal tumor during chemotherapy

Canine transmissible venereal tumor (CTVT) is a tumor that commonly occurs in genital and extragenital sites of both genders. Long interspersed nuclear elements (LINE-1) retrotransposon has a pivotal role in allogenic transfection among uncontrolled dog populations. This study aimed to perform pathomorphological, immunohistochemical, and in situ polymerase chain reaction (PCR) evaluation of CTVT (n = 18) in transfected dogs during chemotherapy. Immunohistochemically, tumor phases were investigated by using specific markers (CD3, CD4, CD8, CD79, and transforming growth factor beta [TGF-β]), and investigated an amplified specific sequence of TVT LINE-1 retrotransposon by in situ PCR. Polyhedral-shaped neoplastic cells that had large, round, hypo/hyperchromatic nuclei and eosinophilic cytoplasm were detected. All marker results were positive, especially in the early weeks of recovery. CD4 and TGF-β markers were conspicuously positive at the initial stage. In situ PCR LINE-1 sequence was initially positive in only four cases. It is believed that the CD and TGF-β markers provide phase identification at tumor initiation and during chemotherapy. It is thought that presence of T and B lymphocytes, which have roles in cellular and humoral immunity, is needed so that regression of the tumor is possible.

Cell proliferation markers in the transplanted canine transmissible venereal tumor / Marcadores de proliferação celular no tumor venéreo transmissível canino transplantado

Adult male mongrel dogs were subcutaneously transplanted with the canine transmissible venereal tumor (TVT) on the hypogastric region. Twelve specimens of tumors were collected, half during the proliferative phase and the other half during the regressive phase. Fragments of the tumor were fixed in 10 percent buffered formalin and routinely processed for light microscopy. Sections of 4µm were stained by Schorr or AgNOR or either immunostained for MIB1 (Ki67). Schorr stain, AgNOR and MIB1 showed an increased proliferative activity through mitotic index, nuclear argyrophilic protein stain and cycling tumoral cells in the growing tumors, respectively. All of the three cell proliferation markers were able to distinguish the TVT in both evolution phases. MIB1 monoclonal antibody was the best in the morphologic evaluation of growth and regression of TVT. This resulted in higher values than AgNORs counting and mitotic index. MIB1 immunostaining was the most effective parameter of the proliferative activity of TVT. However, a significant correlation has been detected only between mitosis counting and AgNORs.

Cães machos, adultos, mestiços, foram transplantados com células do tumor venéreo transmissível canino (TVTC), na região hipogástrica. Foram coletados doze espécimes do TVTC, sendo metade durante a fase proliferativa e metade durante a fase regressiva. Fragmentos do tumor foram fixados em formol a 10 por cento, tamponado e processado rotineiramente para microscopia de luz. Secções de 4µm foram coradas pelo Shorr, ou pela AgNOR, ou ainda, imunocorado para MIB 1 (Ki67). As colorações pelo Shorr, AgNOR, ou MIB 1 mostraram um aumento do índice mitótico, coloração da proteína argirofílica nuclear e células tumorais ciclando em tumores em crescimento, respectivamente. Todos os três marcadores de proliferação celular foram capazes de distinguir o TVTC em ambas as fases de evolução. O anticorpo monoclonal MIB 1 foi o melhor na avaliação morfológica, de crescimento e regressão do TVTC. Isto resultou em um valor maior que a contagem de AgNOR e do índice mitótico. A imunomarcação com MIB1 foi o parâmetro mais efetivo da atividade proliferativa. No entanto, só foi observada uma correlação positiva entre a contagem de mitose e a AgNOR.

TP53 Polymorphisms allow for genetic sub-grouping of the canine transmissible venereal tumor

The canine transmissible venereal tumor (CTVT) is found mainly in dogs' sexual organs. Currently, it is widely accepted that all samples of CTVT show similar histopathological characteristics and share common genetic alterations. Despite the common genetic origin of CTVT, mutations in the P53 gene have been reported. In this study, we proposed that tumor samples can be genetically grouped using this gene. The presence of different subgroups of CTVT was determined in Mexican dogs using the TP53 gene sequence in CTVT samples. Four new polymorphisms were found and therefore, the CTVT samples were classified in five subgroups.