Bisphenol A induces endoplasmic reticulum stress-associated apoptosis in mouse non-parenchymal hepatocytes.
OBJECTIVE
the effects of bisphenol A (BPA) on NCTC Clone 1469, non-parenchymal hepatocytes, were examined to clarify the molecular basis of BPA-induced liver injury.


METHODS
we analyzed the expression of C/EBP homologous protein (CHOP) mRNA, Bcl2 mRNA, caspase12, and glucose-regulated protein 78 kDa (GRP78)/Ig heavy chain-binding protein (BiP), to determine whether endoplasmic reticulum (ER) stress was involved in the 100 μM BPA-induced cell death. To examine the features of damaged hepatocytes, we analyzed the morphological changes in BPA-treated NCTC Clone 1469 by transmission electron microscopy. In addition, we analyzed the intracellular reactive oxygen species (ROS) level in BPA-treated NCTC Clone 1469 by the 2', 7'-dichlorofluorescein diacetate (DCFDA) method.


RESULTS
increases in the expression of CHOP mRNA, caspase-12, and GRP78/BiP in NCTC Clone 1469-treated with 100 μM BPA were detected (CHOP, 1.42 fold; caspase-12, 1.33 fold; GRP78/Bip, 1.36 fold). These observations suggested that BPA induced ER stress-associated apoptosis. A morphological analysis revealed remarkable elongation of the rough ER, supporting the finding of ER stress. Intracellular ROS production was increased in NCTC Clone 1469-treated with BPA, and N-acetyl-l-cysteine (NAC) prevented the cell damage induced by BPA. However, these effects of BPA were not inhibited by estrogen receptor inhibitors.


CONCLUSIONS
we found that BPA induced ER stress-associated apoptosis in non-parenchymal hepatocytes. The ER stress is due to ROS production and is independent of estrogen receptors.
Asahi
Junpei
J
Graduate School of Environmental Engineering, The University of Kitakyushu, Kitakyushu, Fukuoka, 808-0135, Japan.
Kamo
Hanako
H
Baba
Ryoko
R
Doi
Yoshiaki
Y
Yamashita
Akihisa
A
Murakami
Daisuke
D
Hanada
Ayuko
A
Hirano
Takeshi
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001559:Benzhydryl Compounds; D002999:Clone Cells; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000648:ultrastructure; D000091342:Endoplasmic Reticulum Chaperone BiP; D004968:Estrogens, Non-Steroidal / Q000633:toxicity*; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D051379:Mice; D008854:Microscopy, Electron; D010636:Phenols / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D000091342:Endoplasmic Reticulum Chaperone BiP; D004968:Estrogens, Non-Steroidal; D010636:Phenols; D017382:Reactive Oxygen Species; C000717248:Hspa5 protein, mouse; C006780:bisphenol A; D000098826:Bisphenol A Compounds