title: ERK signaling pathway is differentially involved in erythroid differentiation of K562 cells depending on time and the inducing agent.
abstract: K562 cells can be induced to differentiate along the erythroid lineage by a variety of chemical compounds, including hemin, butyrate, cisplatin and ara-C. Differential signaling through MAP kinases has been suggested to be involved in this differentiation process. We have investigated the involvement of ERK activation/inhibition in hemin-, butyrate-, cisplatin- and ara-C-induced erythroid differentiation using the K562 cell line. ERK activity decreased for 2-4h after administration of either inducing agent. ERK was then activated by hemin and cisplatin, while ERK phosphorylation remained decreased during incubation with butyrate and ara-C. There was no activation of JNK or p38. The MEK-1 inhibitors UO126 or PD98059 induced erythroid differentiation in K562 cells and acted additively with butyrate. Inhibition of MEK-1 reduced the hemoglobin accumulation by hemin and cisplatin; erythroid differentiation by ara-C was unchanged. The results suggest that inhibition of signaling through ERK in K562 cells may be needed to enter the erythroid differentiation process, while after initiation both activation and inhibition of signaling through ERK enhance erythroid differentiation, which, however, is dependent on the inducing compound.
authors.affiliation: Department of Pediatric Hematology and Oncology, Justus-Liebig-University, D 35385 Giessen, Germany. wilhelm.woessmann@paediat.med.uni-giessen.de
authors.forename: Willi
authors.initials: W
authors.lastname: Woessmann
authors.forename: Dorothea
authors.initials: D
authors.lastname: Zwanzger
authors.forename: Arndt
authors.initials: A
authors.lastname: Borkhardt
mesh_terms: D002087:Butyrates / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002945:Cisplatin / Q000494:pharmacology; D003561:Cytarabine / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D020014:K562 Cells; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism
chemical_list: D002087:Butyrates; D003561:Cytarabine; D006427:Hemin; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D002945:Cisplatin