title: Cytokine activation of phosphoinositide 3-kinase sensitizes hematopoietic cells to cisplatin-induced death.
abstract: Cytokine growth factors regulate the normal proliferation of hematopoietic cells but can also override irradiation-induced growth arrest checkpoints through activation of a phosphoinositide 3-kinase (PI3K) signaling pathway. In the present study, we assessed the effect that erythropoietin and interleukin-3 have on cisplatin-treated hematopoietic cells. When cultured in the presence of cytokine, cisplatin-treated 32D cells transiently accumulated in a G(2)-M phase arrest and ultimately died by a nonapoptotic mechanism. By comparison, reduction of cytokine-induced PI3K activity, either through cytokine receptor mutation or direct inhibition with LY294002, caused cisplatin-treated cells to enter a biphasic G(1) and G(2)-M arrest. The arrest of these cells coincided with an absence of cyclin-dependent kinase (Cdk)1 and Cdk2 activity and significantly reduced cell death during cisplatin treatment. Indeed, LY294002 treatment during cisplatin exposure allowed the recovery of a viable, proliferating cell population after removal of cisplatin. In contrast, Cdks remained active in the G(2)-M-arrested population of cisplatin-treated cells with continuous cytokine activation of PI3K, and even transient exposure to cisplatin resulted in death of the entire population. These data suggest that cytokine activation of PI3K signaling pathways overrides cisplatin-induced growth arrest checkpoints, thereby sensitizing hematopoietic cells to DNA damage-induced death.
authors.affiliation: Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
authors.forename: Dipali
authors.initials: D
authors.lastname: Nimbalkar
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Henry
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Quelle
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D002945:Cisplatin / Q000008:administration & dosage / Q000494:pharmacology*; D004249:DNA Damage; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004921:Erythropoietin / Q000008:administration & dosage / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D007377:Interleukin-3 / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008938:Mitosis / Q000187:drug effects; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D002945:Cisplatin; D004791:Enzyme Inhibitors; D004921:Erythropoietin; D007377:Interleukin-3; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one