n Experimental Research on the Relation between the Expression of Proliferation Associated Antigens and the Transition from Quiescent Phase to S-phase of Cell Cycle

PCNA is an auxiliary protein of DNA polymerase d, and synthesized during late Gl to S phases in proliferating cells. The cells expressing Ki-67 reactive antigen, another proliferation associated antigen are supposed to be cycling cells. Correlations between positive rate of these antigens and S phase ratio are often discussed, but the relations between expression of these antigens and the transition to S phase are still controversial. Quiescent cells need to express PCNA to enter the proliferating phase, but all cell expressing PCNA do not necessarily enter the S phase. It is true of Ki-67 reactive antigen positive cells, too. In this study, the order of the expression of PCNA and Ki-67 weather arnigen were observed during the transition from quiescent phase to proliferating phase of cell cycle using normal human lymphocytes stimulated by mitogenic agent of PHA (bacto-phytohemagglutinin M). As a result, at 24 hours after PHA stimulation, the PCNA positive rate began to inerease. After another 12 hours, Ki-67 reactive antigen positive rate, and at 48hours after stimulation, BrdU labeling index also began to increase. The correlations between the positive rates of PCNA and Ki-67 reactive antigen, PCNA and BrdU in human tumor tissues were also examined using 15 clinical cases. The result shows that all have significant positive correlation (PCNA:BrdU, r=0.73, p<0.05, Ki-67 reactive antigen:BrdU, r=0.82, p<0.01, PCNA:Ki-67 reactive antigen, r=0.92, p<0.01). There are some differences among the correlations, which may be caused by the order of expression of these proliferation associated antigens.

PCNA

BrdU

Ki-67

PHA刺激リンパ球

細胞周期