[Melatonin in in vitro apoptosis of H22 hepatocarcinoma cells].
OBJECTIVE
To study the effect of melatonin (MLT) in in vitro apoptosis of hepatocarcinoma cells and its mechanism.


METHODS
The apoptotic cells, bcl-2 and bax were detected through immunocytochemical method (ICC) and Tolt-mediated x-duTP nick end labeling (TUNEL). Computer image analysis system was used to quantify the expression of bcl-2 and bax by detecting the absorbance value of positive products. Apoptosis index (AI) was used to quantify the number of apoptotic cells.


RESULTS
In vitro, AI increase was both concentration- and time-dependent through TUNEL. During the same duration, AI of medium dose group was higher than that of low dose and control group (P < 0.05); AI of high dose, medium dose and 5-Fu group were higher than those of low dose and control group (P < 0.01), however, there was no significant difference between the low dose and control group (P > 0.05). At the same dose, in high dose, medium dose and 5-Fu group, the change of AI showed significant difference from 24 to 36 hours (P < 0.05). The expression of bcl-2 was down-regulated as the MLT increased, and there was significant difference between the low dose and control group (P < 0.01). But, the expression of bax was up-regulated as the dose of MLT increased, showing significant difference between the high dose and control groups (P < 0.01). As time went on, the expression of bcl-2 was decreased and in every group, with the change in absorbance value of bcl-2 significantly different from 24 to 36 hours (P < 0.05), whereas that of bax remained almost unchanged. The ratio of bax/bcl-2 was increased with the increase in the concentration of MLT.


CONCLUSIONS
Melatonin may induce apoptosis in the hepatocarcinoma cells which is concentration- and time-dependent, in which bcl-2 and bax are involved.
Gong
Li-hua
LH
Department of Pathology, Tongji Medical College, Huazhong Uninersity of Science and Technology, Wuhan 430030, China.
Ren
Da-hong
DH
Xiong
Mi
M
Lu
Zhi-qiang
ZQ
Wang
Xi-ming
XM
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000473:pathology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy / Q000473:pathology*; D008550:Melatonin / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D013997:Time Factors; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D008550:Melatonin