CYCLIN B1 EXPRESSION IN HELA S3 CELLS STUDIED BY FLOW-CYTOMETRY

Using a procedure to stain cells simultaneously for cyclin B1 protein and DNA, we have examined cyclin B1 expression by flow cytometry in hu man cells under a variety of perturbing and nonperturbing conditions. The method described is useful for measuring relative differences in c yclin B level (immunochemically detectable epitope) as a function of c ell cycle position on an individual cell basis and thus to examine cel l cycle-related changes in cyclin B expression without prior cell sync hronization. We show that in HeLaS3 cells, cyclin B1 accumulates in ce lls only after they become 4C and have resided in G2 for a short perio d of time. During colcemid-induced mitotic arrest cyclin BI continues to accumulate in HeLa S3 cells, and under specific conditions of aphid icolin-induced unbalanced cell growth induced, cyclin B accumulates to supranormal levels prior to mitosis. Flow cytometric analysis of cycl in B expression and DNA content permits detailed examination of the ef fects of cell cycle perturbations on cyclin B expression under a varie ty of conditions. (C) 1994 Academic Press, Inc.