Immunohistochemical expression of dog TERT in canine testicular tumours in relation to PCNA, ki67 and p53 expression.

The objective of the study was to determine the immunohistochemical expression of canine TERT in canine testicular tumours comparing two different antibodies for TERT, and to correlate them with well established markers specific to dividing cells such as PCNA and ki67, and with expression of the p53 tumour suppressor gene. The study included 36 cases of canine testicular tumours, which were categorized as 12 Sertoli Cell Tumours (SCT), 20 seminomas, 3 interstitial cell tumours and 1 mixed germ cell-sex cord stromal tumour (MT). Two antibodies for hTERT were examined; a highly specific TERT antibody, RCK-hTERT, was evaluated for the first time. Immunodetection of RCK-hTERT was observed in 31% of tumours examined (6/20 Seminomas, 4/12 SCT, 1/3 interstitial cell tumour and 0/1 mixed germ cell-sex cord stromal tumour), while the NCL-hTERT in 67% of them (15/20 Seminomas, 6/12 SCT, 3/3 interstitial cell tumour and 0/1 ΜΤ). PCNA immunoreactivity was detected in all cases. Regarding ki67, 3 SCT, 12 seminomas and all interstitial cell tumours showed clear immunoreaction. p53 immunoreactivity was detected in 6 SCT, 15 seminomas and all interstitial cell tumours. The immunohistochemical expression of both TERT antibodies are discussed and compared in order to clarify their potential usefulness in canine testicular malignancies in relation to the expression of well known cell cycle markers. Our results indicate that TERT and PCNA are useful proliferation markers but not helpful to evaluate prognosis. Instead of that ki67 and p53 could be used for predicting aggressiveness in this group of tumours.