title: Insulinlike growth factor-1Ec (MGF) expression in eutopic and ectopic endometrium: characterization of the MGF E-peptide actions in vitro.
abstract: The transcription of the insulinlike growth factor 1 (igf-1) gene generates three mRNA isoforms, namely IGF-1Ea, IGF-1Eb and IGF-1Ec (or MGF [mechano growth factor]). Herein, we analyzed the expression of IGF-1 isoforms in eutopic and ectopic endometrium (red lesions and endometriotic cysts) of women with endometriosis, and we characterized the actions of a synthetic MGF E-peptide on KLE cells. Our data documented that all three igf-1 gene transcripts are expressed in the stromal cells of the eutopic and ectopic endometrium; however, endometriotic cysts contained significantly lower IGF-1 isoform expression, both at the mRNA and protein level, as was shown using semiquantitative PCR and immunohistochemical methods. In addition, the glandular cells of the eutopic endometrium did not express any of the IGF-1 isoforms; however, the glandular cells of the ectopic endometrium (red lesions) did express the IGF-1Ec at mRNA and protein level. Furthermore, synthetic MGF E-peptide, which comprised the last 24 amino acids of the MGF, stimulated the growth of the KLE cells. Experimental silencing of the type 1 IGF receptor (IGF-1R) and insulin receptor expression of KLE cells (siRNA knock-out methods) did not alter the mitogenic action of the synthetic MGF E-peptide, revealing that MGF E-peptide stimulates the growth of KLE cells via an IGF-1R-independent and insulin receptor-independent mechanism. These data suggest that the IGF-1Ec transcript might generate, apart from mature IGF-1 peptide, another posttranslational bioactive product that may have an important role in endometriosis pathophysiology.
authors.affiliation: Department of Experimental Physiology, National and Kapodistrian University of Athens, Goudi-Athens, Greece.
authors.forename: Dimitrios S
authors.initials: DS
authors.lastname: Milingos
authors.forename: Anastassios
authors.initials: A
authors.lastname: Philippou
authors.forename: Athanassios
authors.initials: A
authors.lastname: Armakolas
authors.forename: Efstathia
authors.initials: E
authors.lastname: Papageorgiou
authors.forename: Antigone
authors.initials: A
authors.lastname: Sourla
authors.forename: Athanassios
authors.initials: A
authors.lastname: Protopapas
authors.forename: Anthi
authors.initials: A
authors.lastname: Liapi
authors.forename: Aris
authors.initials: A
authors.lastname: Antsaklis
authors.forename: Minas
authors.initials: M
authors.lastname: Mastrominas
authors.forename: Michael
authors.initials: M
authors.lastname: Koutsilieris
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D045744:Cell Line, Tumor; D003593:Cytoplasm; D004717:Endometrium / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017154:Stromal Cells / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; D034741:RNA, Small Interfering; C523997:mechano-growth factor E, human; D007334:Insulin-Like Growth Factor I