title: Inhibition of hematopoietic progenitor cell growth by Tyr-MIF, an endogenous opiate modulator, and its degradation products.
abstract: There is increasing evidence that neuronal factors can affect hematopoietic cell proliferation. Endogenous opioids with specificity for several opioid receptor classes were tested for their ability to inhibit murine and human hematopoietic progenitor cell proliferation. Tyr-MIF, an opioid tetrapeptide (H-Tyr-Pro-Leu-Gly-NH2), demonstrated a dose-dependent inhibition of colony formation at concentrations < 10 uM, inhibiting M-CSF and G-CSF-responsive progenitor cells equally. Tyr-MIF did not inhibit the number of colonies responsive to recombinant interleukin 3 (rmIL-3) or recombinant murine granulocyte-macrophage colony stimulating factor (rmGM-CSF), but significantly reduced colony size of GM-CSF responsive colonies. Colony formation by human low density and CD34+ marrow cells in response to G-CSF was also inhibited by Tyr-MIF and was more sensitive to inhibition than murine progenitor cells. Colony formation by single CD34+ cells was also inhibited by Tyr-MIF, indicating an effect directly on progenitor cells. Incubation of marrow cells in liquid culture and removal of Tyr-MIF prior to quantitating progenitor cell proliferation demonstrated that opioid-induced inhibition was reversible. The inhibitory effect of Tyr-MIF was not blocked by naloxone, a mu receptor specific antagonist, or diminished in mu opioid receptor deficient mice. HPLC analysis of cell-free culture medium containing Tyr-MIF showed no presence of the parent peptide after 24 h while progenitor cell inhibitory activity was retained. Analysis of potential degradation products of Tyr-MIF indicated that only H-Gly-NH9 or H-Gly-NH2 containing peptides inhibited colony forming unit (CFU) proliferation. These results indicate that Tyr-MIF is a reversible inhibitor of mature hematopoietic progenitor cell proliferation, and that this effect is most likely mediated by the degradation product H-Gly-NH2. Potential applications including protection of myeloid cells after cytosuppresive therapy are discussed.
authors.affiliation: Microbial, Musculoskeletal and Proliferative Disease CEDD, GlaxoSmithKline, Collegeville, PA 19426, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Horowitz
authors.forename: James F
authors.initials: JF
authors.lastname: Callahan
authors.forename: Louis M
authors.initials: LM
authors.lastname: Pelus
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Andrew G
authors.initials: AG
authors.lastname: King
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006131:Growth Inhibitors / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018847:Opioid Peptides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011247:Pregnancy; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D006131:Growth Inhibitors; D018847:Opioid Peptides; D017450:Receptors, Opioid, mu; C036930:tyrosyl-prolyl-leucyl-glycinamide; D009075:MSH Release-Inhibiting Hormone