title: Novel activities of pro-IGF-I E peptides: regulation of morphological differentiation and anchorage-independent growth in human neuroblastoma cells.
abstract: Insulin-like growth factor-I (IGF-I) is translated as a pre-pro-peptide that is posttranslationally processed to its mature form by proteolytic removal of the signal peptide and the E-domain peptide. Contrary to the mature human (h) IGF-I, the recombinant rtEa4 -peptide significantly reduced the anchorage-independent cell growth in human neuroblastoma cells (SK-N-F1), shown by colony formation assay in vitro. Significant inhibition of colony formation is also observed in SK-N-F1 cells stably transfected with a bicistronic expression construct encoding a secretory form of the rtEa4 peptide. Furthermore, treatment with the recombinant rtEa4 peptide, but not the mature hIGF-I, resulted in morphological differentiation of SK-N-F1 cells characterized by long neurite outgrowth. Similar morphological differentiation is also observed in SK-N-F1 cell clones stably transfected with the rtEa4 peptide expression construct. A spectrum of biological activities similar to those of rtEa4 peptide is also observed in the synthetic hEb peptide, but not-the hEa peptide. Results of further characterization reveal that neurites induced by rtEa4 or hEb peptide contain neuronal-specific MAP-2, Tau, and neurofilament (NF-160), accompanied by an increased expression of the neuronal marker gene neuropeptide tyrosine (NPY). Furthermore, effects of signal transduction inhibitors are indicative of the involvement of MAP-kinase PI-3-kinase cascades. The activation of ERK-1/-2 is markedly increased in response to rtEa-4 or hEb peptide stimulation, further indicating the involvement of MAPK signaling cascade. These unique biological activities exhibited by the rtEa4 or hEb peptide suggest that E peptide of the pro-IGF-I may play distinct roles in regulating cell growth and differentiation in neuroblastoma cells.
authors.affiliation: Department of Molecular and Cell Biology and Biotechnology Center, University of Conneticut, Storrs 06269, USA.
authors.forename: Ya-Huei
authors.initials: YH
authors.lastname: Kuo
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Chen
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000737:chemistry / Q000494:pharmacology*; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D016501:Neurites / Q000737:chemistry / Q000187:drug effects; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology*; D010455:Peptides / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011498:Protein Precursors / Q000737:chemistry / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D015415:Biomarkers; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009025:Morpholines; D010455:Peptides; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011498:Protein Precursors; D011994:Recombinant Proteins; C119953:pro-insulin-like growth factor I; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007334:Insulin-Like Growth Factor I; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one