Retinoic acid-mediated differentiation protects against nitrofen-induced apoptosis.
BACKGROUND
Nitrofen is a diphenyl ether that induces a spectrum of birth defects subsequent to administration to pregnant rodents, in which the molecular etiology of these defects are poorly characterized. Because previous reports showed that nitrofen induced apoptosis in undifferentiated P19 teratocarcinoma cells, we hypothesized that undifferentiated fetal cells have greater susceptibility to nitrofen-induced apoptosis than their differentiated derivatives.


METHODS
To investigate this hypothesis, cell lines including P19 and F9 were differentiated with retinoic acid into neuronal and endodermal derivatives respectively. Apoptosis was characterized by caspase-3 cleavage and Terminal transferase dUTP nick end labeling (TUNEL) assays.


RESULTS
Both differentiated cell-types had reduced nitrofen-induced caspase-3 cleavage and DNA fragmentation compared with the naive controls, strongly suggesting that differentiation of these cells protects against nitrofen-induced apoptosis. In addition, resistance to apoptotic induction was proportional to the expression levels of the differentiation marker, p27 (kip1) while direct proportionality was not observed for the antiapoptotic protein Bcl-2.


CONCLUSIONS
These studies show that nitrofen may induce its associated birth defects via a mechanism involving apoptosis of undifferentiated fetal cells.
Aidlen
Jeremy T
JT
Pediatric Surgical Research Laboratories, Department of Pediatrics, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Nazarey
Pradeep P
PP
Kinane
T Bernard
TB
Donahoe
Patricia K
PK
Schnitzer
Jay J
JJ
Kling
David E
DE
D000014:Abnormalities, Drug-Induced / Q000209:etiology / Q000473:pathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D006540:Herbicides / Q000633:toxicity; D051379:Mice; D010647:Phenyl Ethers / Q000633:toxicity*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
D006540:Herbicides; D010647:Phenyl Ethers; D019253:Proto-Oncogene Proteins c-bcl-2; D014212:Tretinoin; C505409:Casp3 protein, mouse; D053148:Caspase 3; C007350:nitrofen