title: Inhibition of enriched stem cells in vivo and in vitro by the hemoregulatory peptide SK&F108636.
abstract: Replacement of the labile sulfhydryl group (-SH) of the hemoregulatory peptide monomer pyroGluGluAspCysLys (HP5b) with an isosteric methylene group yields a chemically stable compound, SK&F108636. In this study, we describe the effects of SK&F108636 on highly enriched Lin-Sca1+ hematopoietic stem cells. SK&F108636 significantly reduced the fraction of cycling progenitor cells, granulocyte macrophage colony-forming cells (GM-CFC), in vitro and in vivo. There was no effect on GM-CFC or Mix-CFC colony formation. SK&F108636 significantly inhibited proliferation of high proliferative potential (HPP)-CFC in semisolid agar cultures stimulated by stem cell factor + interleukin 3 (IL-3) + IL-1, but had no effect in cultures stimulated with M-CSF + IL-3 + IL-1. SK&F108636 was shown to act directly on the stem cells since SK&F108636 inhibited proliferation of Lin-Sca1+ cells in single cell assays. Administration of SK&F108636 to lethally irradiated mice transplanted with 2000 Lin-Sca1+ cells significantly inhibited proliferation/differentiation of cells developing into colony forming units-spleen (CFU-S) (preCFU-S) and the reconstitution of HPP-CFC and GM-CFC. There was no effect of SK&F108636 on CFU-S colony formation or mature cell regeneration in bone marrow, spleen and blood. Hence, the hemoregulatory peptide monomer SK&F108636 is a potent primitive stem cell inhibitor in vivo and in vitro. Inhibition of stem cell proliferation by small specific inhibitors may protect hematopoiesis from myelotoxic side effects during chemotherapy treatment.
authors.affiliation: Nycomed Pharma AS, Diagnostica and Exploratory Therapy R&D, Olso, Norway.
authors.forename: O P
authors.initials: OP
authors.lastname: Veiby
authors.forename: S
authors.initials: S
authors.lastname: LoCastro
authors.forename: P
authors.initials: P
authors.lastname: Bhatnagar
authors.forename: W M
authors.initials: WM
authors.lastname: Olsen
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006410:Hematopoiesis / Q000187:drug effects*; D007375:Interleukin-1 / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009842:Oligopeptides / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives
chemical_list: D007375:Interleukin-1; D007377:Interleukin-3; D009842:Oligopeptides; C102814:SK&F 108636; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011761:Pyrrolidonecarboxylic Acid