Insulin-like growth factor-binding protein-3 promotes transforming growth factor-{beta}1-mediated epithelial-to-mesenchymal transition and motility in transformed human esophageal cells.
Insulin-like growth factor-binding protein (IGFBP)-3 is overexpressed frequently in esophageal squamous cell carcinoma. Yet, the role of IGFBP3 in esophageal tumor biology remains to be elucidated. We find that IGFBP3 facilitates transforming growth factor (TGF)-beta1-mediated epithelial-to-mesenchymal transition (EMT) in transformed human esophageal epithelial cells, EPC2-hTERT-EGFR-p53(R175H). In organotypic 3D culture, a form of human tissue engineering, laser-capture microdissection revealed concurrent upregulation of TGF-beta target genes, IGFBP3 and EMT-related genes in the cells invading into the stromal compartment. IGFBP3 enhanced TGF-beta1-mediated EMT as well as transcription factors essential in EMT by allowing persistent SMAD2 and SMAD3 phosphorylation. TGF-beta1-mediated EMT and cell invasion were enhanced by ectopically expressed IGFBP3 and suppressed by RNA interference directed against IGFBP3. The IGFBP3 knockdown effect was rescued by IGFBP3(I56G/L80G/L81G), a mutant IGFBP3 lacking an insulin-like growth factor (IGF)-binding capacity. Thus, IGFBP3 can regulate TGF-beta1-mediated EMT and cell invasion in an IGF or insulin-like growth factor 1 receptor-independent manner. IGFBP3(I56G/L80G/L81G) also promoted EMT in vivo in a Ras-transformed human esophageal cell line T-TeRas upon xenograft transplantation in nude mice. In aggregate, IGFBP3 may have a novel IGF-binding independent biological function in regulation of TGF-beta1-mediated EMT and cell invasion.
Natsuizaka
Mitsuteru
M
Department of Medicine, University of Pennsylvania, Philadelphia, 19104, USA.
Ohashi
Shinya
S
Wong
Gabrielle S
GS
Ahmadi
Azal
A
Kalman
Ross A
RA
Budo
Daniela
D
Klein-Szanto
Andres J
AJ
Herlyn
Meenhard
M
Diehl
J Alan
JA
Nakagawa
Hiroshi
H
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects; D004938:Esophageal Neoplasms / Q000473:pathology; D004947:Esophagus / Q000166:cytology* / Q000187:drug effects / Q000473:pathology; D055785:Gene Knockdown Techniques; D018014:Gene Transfer Techniques; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000172:deficiency / Q000235:genetics / Q000494:pharmacology*; D016086:Lentivirus / Q000235:genetics; D008156:Luciferases / Q000235:genetics; D008648:Mesoderm / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D009361:Neoplasm Invasiveness; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D018972:Insulin-Like Growth Factor Binding Protein 3; D053773:Transforming Growth Factor beta1; D008156:Luciferases