[The theory of flow cytometric analysis of the cell cycle and their applications in biology and oncology].

The clockwise concept of cell cycle kinetics has changed since molecular biology made rapid advances in this area and added somewhat to cell cycle analysis by DNA histogram. During the last decade, it has been made possible to measure many cell-cycle-regulating gene products flow cytometrically. Application of bromodeoxyuridine (BrdU) to cell cycle analysis contributes to scientific progression in many fields of biology and oncology. In this article, we attempt to summarize the outline of new concepts regarding the cell cycle by means of flow cytometric techniques and to describe their application in biology and oncology. For this purpose, probes, biological differences amongst the dyes used, DNA analysis using DNA histograms and their limitations are explained. Next, new methods to analyse cell cycle kinetics by means of BrdU, Ki-67 antigen, cyclin, etc. discussed. As far as application of flow cytometric cell cycle analysis are concerned, influences of nutrition, growth factors and hormones, relationships between DNA index or cell cycle and the prognosis of patients with cancer, and the effect of anticancer drugs on the cell cycle are discussed. Finally, we emphasize the importance of multiparameter analysis of cell cycle kinetics using flow cytometry.