Dados do Resumo

Título

PROLIFERATION BIOMARKER IN CANINE SEMINOMAS: PRELIMINARY RESULTS FROM AN ANIMAL MODEL.

Introdução

Seminoma is one of the most frequent testicular tumors in dogs, mainly old ones, with orchiectomy as single curative therapy. Canine seminoma resembles spermatocytic seminoma in man. Though less aggressive and of low metastatic risk, it is an important neoplasm in man, sometimes requiring chemotherapy. Topoisomerase-2-alpha is a nuclear enzyme found in cells under mitosis and is considered a proliferation biomarker besides being a chemotherapy drug target. It is highly conserved across species.

Objetivo

To evaluate topoisomerase 2 alpha immunohistochemical expression in canine seminomas diagnosed in testicular samples retrieved from UFF Veterinary Pathological Anatomy Laboratory archive, regarding proliferation rate and investigating male dogs potential as an animal model of this tumor in man.

Métodos

UFF Ethics Committee in Animal Use approval n. 8227220922. Six formalin-fixed paraffin embedded canine testicular seminoma samples were histopathologically revaluated and processed through streptavidin-biotin-peroxidase immunohistochemical technique and analyzed under optical microscopy by two researchers. Age of included dogs was recorded when available. Sections were incubated overnight with anti-topoisomerase-2-alpha primary antibody (1:200, mouse monoclonal, Dako) and diaminobenzidine (DAB) was used as chromogen with Harris hematoxylin counterstain. Seminoma was classified regarding seminiferous tubule location in intratubular or diffuse in HE sections. Topoisomerase-2-alpha expression was calculated as positive immunostained cells percentage considering brown nuclear immunostained tumoral cells evaluated under high power fields. Results were evaluated by descriptive statistics tools.

Resultados

Age of included dogs ranged from 10 to 15 years, with average of 13,2 years old. From six seminomas, three were classified as intratubular and the other three as diffuse. Topoisomerase-2-alpha immunostaining was identified in five samples as brown granular nuclear immunostaining. One diffuse seminoma was negative. Percentage of positive cells varied from 0,22% to 1,54%, with 0,91% average in five positive samples, differing from previous reports in human seminoma, in which topoisomerase-2-alpha index range over 40% positivity. Topoisomerase-2-alpha index was low in studied samples and was not considered overexpressed in evaluated canine seminomas, differing from results in human seminoma.

Conclusões

Seminoma occurred in old male dogs, similar to spermatocytic seminoma in man around 50 years old. Topoisomerase-2-alpha immunoexpression was low in evaluated canine seminoma samples, with proliferation index not reaching 2% positivity. Further studies are required in other to fully understand this biomarker low proliferation index and its role in canine seminoma tumoral evolution.

Financiador do resumo

This study was funded/financed in part by FAPERJ—Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro.

Palavras Chave

seminoma; proliferation biomarker; animal model