Evaluation of Cell Proliferation in Canine Tumors by the Bromodeoxyuridine Labeling Method, Immunostaining of Ki-67 Antigen and Proliferating Cell Nuclear Antigen

Abstract

Cell proliferation activity and correlation between the LI (labeling index) of BrdU (5-bromo-2'-deoxy-uridine) and the expression of the Ki-67 antigen or PCNA (proliferating cell nuclear antigen) were evaluated by immunohistochemistry in 18 canine spontaneous neoplasms. Spearman's rank correlation coefficient and linear regression analysis revealed a significant correlation between the BrdU LI and Ki-67 LI, BrdU LI and PCNA LI, and BrdU LI and MI (mitotic index) in each case [rs = 0.917, P < 0.01 (BrdU LI vs. Ki-67 LI), rs = 0.736, P < 0.01 (BrdU LI vs. PCNA LI), rs = 0.748, P < 0.01 (BrdU LI vs. MI) by Spearman's rank correlation coefficient; and r = 0.918, P < 0.01 (BrdU LI vs. Ki-67 LI), r = 0.626, P < 0.01 (BrdU LI vs. PCNA LI), r = 0.763, P < 0.01 (BrdU LI vs. MI) by linear regression analysis]. Ki-67 LIs were more closely correlated with BrdU LIs than PCNA LIs or MIs, and the Ki-67 antigen is useful as an endogenous proliferation marker in canine neoplasms.