Telomerase activity and immunohistochemical expression of PCNA, p53 and ki67 in testicular tumours of dogs
Testicular tumours are common in aged dogs and include germ cell tumours (seminoma, teratoma, embryonal carcinoma), sex cord-stromal tumours (Sertoli cell tumours and interstitial cell tumours) and mixed germ cell-sex cord stromal tumours. Seminoma, Sertoli cell tumours (SCTs) and interstitial cell tumours are the most common tumour types observed and occur with approximately equal frequency. The aim of this study was to examine the immunohistochemical expression of telomerase and certain established tumour markers (PCNA, p53 and ki-67) in a range of canine testicular tumour types and to examine the interrelations between them. Serial sections from 36 formalin-fixed testicular tumours (20 seminomas, 12 SCTs, 3 interstitial cell tumours and 1 mixed germ cell-cord stromal tumour) were either stained with hematoxylin and eosin or were stained immunohistochemically using primary antibodies against PCNA (Oncogene), p53 and ki-67 (both Dako), and telomerase (h-TERT,Novocastra). Immunohistohemical analysis was also performed in four normal canine testes. 15/20 seminomas and 6/12 SCTs were positive for p53. All seminomas (20/20) and SCTs (12/12) showed strong nuclear activity with PCNA while only 2/20 and 3/12 were stained with ki-67 respectively. h-TERT protein was detectd in 15 seminomas and 6 SCTs either intracytoplasmically or intranuclearly 15 of 20 seminomas were positive for p53 and the ki-67 immmunostaining was expressed in two of them. The diffuse type of the above tumours were strongly expressed h TERT. The interstitial cell tumors were immunoreactive to all examined antibodies. The mixed tumor was only positive for PCNA. Our results support the hypothesis that p53 inactivation is involved in the malignant progression of seminomas. Moreover, they suggest that quantitation of PCNA-positive nuclei provides an objective method for assessing proliferative activity in testicular tumours, while immunohistochemical examination for ki-67 may be of limited value. Telomerase activity was demonstrated in both seminomas and SCTs. Telomerase activation appears to be a rather early event in canine testicular cancer progression. Examination of the relationship of these results with telomerase expression levels in testicular tumours, a study currently under way, may further elucidate its role in testicular cancer progression
Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης, Σχολή Επιστημών Υγείας, Τμήμα Κτηνιατρικής
Proceedings of the 24th Meeting of the European Society of Veterinary Pathology,  p.79-79 [Published Version]
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