Effect of interferon-beta on the cell cycle of human glioma cell line U-251 MG: flow cytometric two-dimensional (BrdU/DNA) analysis.

This paper describes the determination of the effect of IFN-beta on U-251 MG cells using the bromodeoxyuridine (BrdU/DNA) analysis technique. The cell cycle perturbation of exponentially growing cells was estimated by a newly developed two-dimensional analysis of sequential BrdU/DNA distributions measured at 4-hr intervals after IFN-beta administration. The U-251 MG cell line was sensitive to IFN-beta, and cell proliferation was inhibited by 50.0% at 48 hr. Analysis of DNA histograms indicated that IFN-beta accumulated the cells in the S-phase, from 16 to 48 hr after treatment. In the two-dimensional analysis, labeled cells treated with IFN-beta moved from the S-phase through the G2M-phase and then entered the G1-phase within 12 hr after the initial treatment, in a pattern similar to labeled cells untreated with IFN-beta. After 16 hr, labeled cells treated with IFN-beta began to accumulate in the S-phase and remained there even after 48 hr. These results imply that IFN-beta may have an effect on the G1-phase, thereby inducing S-phase accumulation of human glioma cell line U-251 MG.