title: Combined use of nonmyelosuppressive nitrosourea analogues with hydroxyurea in the induction of F-cell production in a human erythroleukemic cell line.
abstract: OBJECTIVE
  Although hydroxyurea (HU) has been used clinically to treat patients with sickle cell disease (SCD), not all patients benefit from HU treatment due to its toxicity. The objective of this study was to investigate the effectiveness of the use of two new Hb F-inducing nitrosourea analogues, 2-[3-(2-methyl, 2-nitroso) ureido]-2-deoxy-D-glucopyranose (MNGU) and 2-[3-(2-chloroethyl) ureido]-2-deoxy-D-glucopyranose (CGU), in combination with HU in K562 cells or erythroid progenitors.
  
  
  METHODS
  After K562 cells were cultured with different concentrations of HU with CGU or MNGU, aliquots of the cells were obtained to determine the total (benzidine-positive) hemoglobin level, number of F cells, and Hb F level. Erythroid progenitor cells of SCD patients and healthy donors were cultured with the optimal drug concentrations, and the number of BFU-E and Hb F level were determined.
  
  
  RESULTS
  Our results showed that the combined use of HU with CGU or MNGU increased the number of both benzidine-positive normoblasts and F cells in a synergistic manner. Further, a lower concentration of HU was required to induce a significant level of Hb F synthesis when combined with either of the two compounds in comparison with treatment with HU alone. On day 4, the number of benzidine-positive cells was 4.5- to 6.5-fold and the number of F cells was 5.0- to 8.0-fold higher than the respective numbers in the untreated K562 cells. Similarly, a 3.2- to 14.3-fold induction of Hb F was obtained when human erythroid progenitors from SCD patients were treated with the same drug combinations.
  
  
  CONCLUSIONS
  Based on these results, the use of CGU or MNGU in combination with HU might offer substantial benefits to patients with SCD and other hemoglobinopathies.
authors.affiliation: Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104-4399, USA. iyamu@email.chop.edu
authors.forename: Efemwonkiekie W
authors.initials: EW
authors.lastname: Iyamu
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Adunyah
authors.forename: Hugo
authors.initials: H
authors.lastname: Fasold
authors.forename: Kazumi
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Surendra
authors.initials: S
authors.lastname: Baliga
authors.forename: Kwaku
authors.initials: K
authors.lastname: Ohene-Frempong
authors.forename: Ernest A
authors.initials: EA
authors.lastname: Turner
authors.forename: Toshio
authors.initials: T
authors.lastname: Asakura
mesh_terms: D002455:Cell Division / Q000187:drug effects; D005319:Fetal Hemoglobin / Q000096:biosynthesis*; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology*; D020014:K562 Cells; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology; D009005:Monosaccharides / Q000494:pharmacology*; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: C476299:2-(3-(2-chloroethyl) ureido)-2-deoxy-D-glucopyranose; C476298:2-(3-(2-methyl, 2-nitroso) ureido)-2-deoxy-D-glucopyranose; D009005:Monosaccharides; D014508:Urea; D005319:Fetal Hemoglobin; D006918:Hydroxyurea