Exogenous phosphatidylethanolamine induces apoptosis of human hepatoma HepG2 cells via the bcl-2/Bax pathway.
OBJECTIVE
To investigate the signaling pathways implicated in phosphatidylethanolamine (PE)-induced apoptosis of human hepatoma HepG2 cells.


METHODS
Inhibitory effects of PE on human hepatoma HepG2 cells were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle, apoptosis and mitochondrial transmembrane potential (DeltaPsi m) were analyzed by flow cytometry. Immunocytochemical assay and Western blotting were used to examine Bcl-2, Bax and caspase-3 protein levels in HepG2 cells treated with PE.


RESULTS
PE inhibited the growth of HepG2 cells in a dose- and time- dependent manner. It did not affect the cell cycle, but induced apoptosis. PE significantly decreased DeltaPsi m at 0.25, 0.5 and 1 mmol/L, respectively, suggesting that PE induces cell apoptosis by decreasing the mitochondrial transmembrane potential. The Bcl-2 expression level induced by different concentrations of PE was lower than that in control groups. However, the Bax expression level induced by PE was higher than that in the control group. Meanwhile, PE increased the caspase-3 expression in a dose- and time-dependent manner.


CONCLUSIONS
Exogenous PE induces apoptosis of human hepatoma HepG2 cells via the bcl-2/bax pathway.
Yao
Yu
Y
Department of Genetics and Molecular Biology, Medical School, Xi'an Jiaotong University/Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an, Shaanxi Province, China.
Huang
Chen
C
Li
Zong-Fang
ZF
Wang
Ai-Ying
AY
Liu
Li-Ying
LY
Zhao
Xiao-Ge
XG
Luo
Yu
Y
Ni
Lei
L
Zhang
Wang-Gang
WG
Song
Tu-Sheng
TS
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D010714:Phosphatidylethanolamines / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism*
D010714:Phosphatidylethanolamines; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D053148:Caspase 3