[p53-dependent antiproliferation and apoptosis of H22 cell induced by melatonin].
OBJECTIVE
It has been shown that melatonin has a direct inhibitory effect on the proliferation of H22 mouse hepatoma cells in our research. This study was designed to investigate its molecular mechanism.


METHODS
(1) Animal models were established by transplanting H22 cells and treated with melatonin, and then the p53 and cyclin E of the tumor tissue were determined by immunohistochemical analysis. (2) After treatment of H22 cells with melatonin in vitro, the percentage of cells in each cell cycle phase and apoptosis rate were analyzed by flow cytometry. p53 and cyclin E were determined again by immunohistochemical analysis. The level of Fas mRNA was examined by real time polymerase chain reaction (RT-PCR).


RESULTS
(1) After treated with melatonin (1 x 10(-6) mol/L), the number of the H22 cells in phase G(0)/G(1) were elevated from 75.24% to 85.46%, while which in phase S almost decreased from 10.32% to 0, and at the same time, the number of apoptotic cells increased from 5.07% to 12.77%. (2) Compared with the control, the level of p53 elevated 42.5% (in vitro) and 19.5% (in vivo), however, the level of cyclin E decreased 31.7% (in vitro) and 39.9% (in vivo). (3) Fas mRNA increased about 44.2% after melatonin treatment (P< 0.01).


CONCLUSIONS
Melatonin inhibits the proliferation of H22 cells by arrest and apoptosis, and the mechanism perhaps interferes with increasing p53 that results in down-regulation of cyclin E indirectly and stimulates the expression of Fas gene.
She
Mei-Hua
MH
Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, P.R.China. shemh93013@hotmail.com
Chen
Bei-Bei
BB
Wang
Xi-Ming
XM
He
Shan-Shu
SS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019927:Cyclin E / Q000378:metabolism*; D053222:Fas Ligand Protein; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D019927:Cyclin E; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D008550:Melatonin