title: Cyclin B1 expression in response to abrogation of the radiation-induced G2/M block in HeLa cells.
abstract: The G2 block is a major response of cells to DNA damage and seem to be induced independently of p53 status. It is thought that the G2 block has a protective function and allows cells to repair their DNA. The molecular events involved in the formation of the G2 block therefore are of great interest. We have used pentoxifylline, a potent G2 delay abrogator, to study the expression of an essential component of the mitosis promoting complex (MPF), cyclin B1. Cyclin B1/G2 ratios are used to show that irradiation induces a decrease in cyclin B1 expression and that pentoxifylline restores cyclin B1 expression to control level. This confirms that suppression of cyclin B1 plays a role in the formation of the G2 cell cycle delay, and that elevating cyclin B1 expression is part of the mechanism of action of pentoxifylline on G2 blocked cells.
authors.affiliation: Department of Radiation Oncology, University of Stellenbosch Medical Faculty, Tygerberg, South Africa.
authors.forename: T
authors.initials: T
authors.lastname: Theron
authors.forename: L
authors.initials: L
authors.lastname: Böhm
mesh_terms: D002453:Cell Cycle / Q000502:physiology / Q000528:radiation effects*; D019926:Cyclin B / Q000096:biosynthesis / Q000235:genetics*; D056744:Cyclin B1; D004247:DNA / Q000032:analysis; D004249:DNA Damage; D016195:G2 Phase; D005786:Gene Expression Regulation / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008938:Mitosis; D013997:Time Factors
chemical_list: C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D004247:DNA