Fibroblast growth factor signaling in the developing tracheoesophageal fistula.
OBJECTIVE
The Adriamycin-induced rat model of esophageal atresia and tracheoesophageal fistula (EA/TEF) provides a reliable system for the study of EA/TEF pathogenesis. The authors previously hypothesized that faulty branching lung morphogenesis pathways were a critical component of its pathogenesis. The authors have found evidence for faulty fibroblast growth factor (FGF) signaling related to epithelial-mesenchymal interactions in the fistula tract. To better define FGF signaling, the differential expression of FGF ligands and their receptors between lung, fistula tract, and esophagus are described.


METHODS
Time-dated pregnant, Sprague-Dawley rats were injected with Adriamycin (2 mg/kg intraperitoneally) on days 6 through 9 of gestation. Tissues were processed for histology and reverse transcriptase polymerase chain reaction. FGF-1, -7 and -10 were measured from whole lung, fistula tract, and esophagus of TEF or normal embryos. Expression of FGF2RIIIb and FGF2RIIIc receptors was measured in isolated epithelium and mesenchyme of lung and fistula tract of TEF embryos as well as lung and esophagus from normal controls.


RESULTS
FGF-1 mRNA was present in the fistula tract and normal and Adriamycin-exposed lung but absent from whole esophagus. Interestingly, FGF-7 mRNA was present only in normal lung. FGF-10 was present in all tissues examined. FGF2RIIIb mRNA was absent in fistula mesenchyme but present in all other tissues examined. However, the splice variant FGF2RIIIc mRNA was present in all tissues examined.


CONCLUSIONS
These findings support defective FGF signaling in the rat model of EA/TEF. Absence of FGF-7 mRNA in Adriamycin-exposed tissues suggests the primary effect of Adriamycin may be to inhibit FGF-7 expression. Moreover, absence of FGF2RIIIb in fistula mesenchyme may be caused by loss of positive feedback from FGF-7, its normal obligate ligand. Understanding these specific defects in FGF signaling may provide insight into faulty mechanisms of EA/TEF.
Spilde
Troy L
TL
Division of Pediatric Surgery, Childen's Mercy Hospital, Kansas City, Missouri 64108, USA.
Bhatia
Amina M
AM
Marosky
Julie K
JK
Preuett
Barry
B
Kobayashi
Hiroyuki
H
Hembree
Mark J
MJ
Prasadan
Krishna
K
Daume
Erica
E
Snyder
Charles L
CL
Gittes
George K
GK
D000014:Abnormalities, Drug-Induced / Q000209:etiology / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000015:Abnormalities, Multiple / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D004195:Disease Models, Animal; D004317:Doxorubicin / Q000633:toxicity*; D004848:Epithelium / Q000378:metabolism; D004933:Esophageal Atresia / Q000139:chemically induced / Q000196:embryology / Q000235:genetics*; D004947:Esophagus / Q000196:embryology / Q000378:metabolism; D005260:Female; D005326:Fetal Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D008168:Lung / Q000196:embryology / Q000378:metabolism; D008648:Mesoderm / Q000737:chemistry; D009024:Morphogenesis / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014132:Trachea / Q000196:embryology / Q000378:metabolism; D014138:Tracheoesophageal Fistula / Q000139:chemically induced / Q000196:embryology / Q000235:genetics*
D005326:Fetal Proteins; C496455:Fgf7 protein, rat; D017468:Receptors, Fibroblast Growth Factor; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D004317:Doxorubicin; D051497:Receptor, Fibroblast Growth Factor, Type 2; C065104:keratinocyte growth factor receptor