title: 1,10-Phenanthroline inhibition of lymphoblast cell cycle.
abstract: The effects of the metal-chelating agent, 1,10-phenanthroline (OP), on the cell cycle progression of CCRF-CEM lymphoblasts has been studied by flow microfluorometry. Lymphoblasts were incubated with 2,3-dihydro-1H-imidazo[1,2-b]pyrazole in order to block them in G1-early S. The block was then reversed by incubating the cells in fresh media. Within 2 to 4 hr, approximately 90% of the cells were in S phase and, by 6 hr, approximately 80% were in late S. Aliquots of these latter cells then were incubated with podophyllotoxin to block them in G2-M. These cells divided within 4 hr of reversal of the podophyllotoxin block. Lymphoblast populations in G1-early S, mid-S, or G2-M were then incubated with 4 micronM OP. OP blocked entry of G1 cells into S as well as progression through S but had no effect on progression from G2-M to G1. The OP effects were reversed by addition of Zn2+, Cu2+, or Fe2+ or by dilution of the chelating agent in the growth media. Incubation of CCRF-CEM lymphoblasts with 1,7-phenanthroline, a nonchelating analog of OP, did not affect the cell cycle. The data indicate that OP reversibly blocks progression of cells from G1 to S and through S by chelation of metals involved in processes essential for those cell cycle events.
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000032:analysis; D007536:Isomerism; D007938:Leukemia / Q000378:metabolism / Q000473:pathology; D008214:Lymphocytes / Q000032:analysis / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010618:Phenanthrolines / Q000494:pharmacology*; D015032:Zinc / Q000378:metabolism
chemical_list: D010618:Phenanthrolines; D004247:DNA; D015032:Zinc