[Experimental study on apoptosis of gastric cancer cell line MKN45 induced by continuous irradiation from iodine-125 seeds].
OBJECTIVE
To investigate the apoptotic effect of iodine-125 seeds on gastric cancer cell line MKN45 and its changes, including the changes of cellular morphosis, early apoptotic rate and Bcl-2/Bax expression, and to provide further evidence for the clinical application of iodine-125 seeds on gastric cancer.


METHODS
Human gastric cancer cell line MKN45 in treatment group was continuously exposed to discoid radiative sources made by seven iodine-125 seeds, while the control group not treated. 72 hours later, the gastric cancer cells in each group were collected, and observed respectively under light and electron microscope. Apoptotic rate were detected with DAPI staining. Early apoptotic rate was detected by flow cytometry (FCM). And Bcl-2/Bax expression was detected by RT-PCR.


RESULTS
1) Typical morphologic changes of apoptotic cells were observed under light and electronic microscope in treatment group. 2) Apoptotic rate detected with DAPI staining in treatment group was higher than that in control group (p<0.01). 3) Early apoptotic rate in treatment group was higher than that in control group (P<0.01). 4) Increased intracellular Bax expression level detected by RT-PCR in treatment group was observed (P<0.01). 5) Bax expression level in treatment group was increased obviously, with the decrese of Bcl-2 expression by semi-quantitative RT-PCR detection. The ratio of Bcl-2 to Bax in treatment group was lower than that in control group.


CONCLUSIONS
Continous irradiation by iodine-125 seeds can induce apoptosis of human gastric cancer cell line MKN45. The decreasing ratio of Bcl-2 to Bax may be one of the mechanism of human gastric cancer cell line MKN45's apoptosis.
He
Qi-ming
QM
Department of General Surgery, West China Hospital, Sichuan University, Chengdu 61004, China.
Wu
Xiao-ting
XT
D017209:Apoptosis / Q000528:radiation effects*; D045744:Cell Line, Tumor; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D013274:Stomach Neoplasms / Q000473:pathology*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects
D007457:Iodine Radioisotopes; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein