Abstract 303: A tissue microarray-based study of the basal cell in canine prostatic hyperplastic, pre-neoplastic and neoplastic lesions.

Abstract

Abstract It has been stated that dog is the best natural model to study carcinogenesis in comparison with men. In addition, the loss of the basal cell layer integrity is one of the main characteristics in human pre-neoplastic and neoplastic prostatic lesions. In human normal prostate, the basal cells selectively express p63 in their nuclei, demonstrating basal cell layer integrity. However, in both primary and metastatic prostate carcinomas, has been described absence of p63 immunoexpression. This study aimed to evaluate the involvement of basal cells (p63 and 34βE12) and proliferative index (ki-67) in prostatic pre-neoplastic and neoplastic lesions from dogs. A tissue microarray (TMA) was constructed using 66 canine prostatic paraffin-embedded lesions, selecting appropriate and representative areas of normal tissue (n=7), benign prostatic hyperplasia (BPH, n= 18), prostatic inflammatory atrophy (PIA, n=22) and prostatic carcinoma (PCa, n=19). Immunohistochemistry was performed using peroxidase method and DAB. The immunohistochemical staining was assessed by scores according the distribution of positive cells for p63 and 34βE12 (score 1: <25% cells positive, 2: 26% to 50%, 3: being 51% and 75% and 4:> 75%) and for Ki67, positive nuclei were counted in each lesion. Chi-square or Fisher exact test was used to determine the association between the categorical variables and student t test to compare proliferative index among lesions. Concerning the p63 protein, we found higher number of cases with more than 75% of positive basal cells in CaP (p=0.002) and PIA (p= 0.0042) when compared to normal tissue and BPH. CaP and PIA showed 34βE12 protein expression when compared to normal prostatic tissue and BPH (p= 0.032, p=0.0064). There was no statistically significant difference in the comparison between PIA and BPH. Ki67 showed higher proliferative index in PCa (p= 0.0028) and PIA (p= 0.01) compared to normal tissue and BPH. Higher p63 and 34βE12 immunohistochemical staining as well as higher proliferative index in these cells were observed in canine pre-neoplastic lesion (PIA) and prostate carcinoma indicate the involvement of basal cells in these lesions in dogs, different from humans. These results do not support the dog as the best natural model to the study of all types of prostatic carcinomas in men. Financial support: Fapesp Citation Format: Renée Laufer Amorim, Carlos Eduardo Fonseca-Alves, Marcela M p Rodrigues, Silvia Regina Rogatto. A tissue microarray-based study of the basal cell in canine prostatic hyperplastic, pre-neoplastic and neoplastic lesions. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 303. doi:10.1158/1538-7445.AM2013-303