Analysis of cell cycle-related Ki-67 and p120 expression by flow cytometric BrdUrd-Hoechst/7AAD and immunolabeling technique

Abstract

Flow cytometric multiparameter analysis of two proliferation associated antigens, Ki-67 and p120, was combined with cell cycle kinetic analysis, achieved by continuous labeling with 5-Bromodeoxyuridine (BrdUrd), followed by staining with Hoechst 33258 and 7-Aminoactinomycin D (7AAD). Exponential and plateau phase monolayer cultures of the human bladder carcinoma cell line J82 were examined. Resting cells, characterized by their absent BrdUrd incorporation, showed no reactivity with the MIB1 antibody, which was used for the detection of the Ki-67 antigen. Proliferating cells revealed a cell cycle phase dependent Ki-67 staining intensity, which was partially related to the time period spent in G1 after mitosis. In contrast to the Ki-67 antigen expression, no decrease in p120 immunofluorescence staining intensity of non-cycling cells could be observed. We could demonstrate that a dissection of the history of cell replication, obtained by the BrdUrd/Hoechst technique combined with a simultaneous immunofluorescence staining reveals detailed information, on a single cell level, about time dependent expression of proliferation associated antigens in all cell cycle compartments.