Heavy ion irradiation increases apoptosis and STAT-3 expression, led to the cells arrested at G2/M phase in human hepatoma SMMC-7721 cells.
BACKGROUND
The impact of STAT-3 expression on the apoptosis of human hepatomas cell SMMC-7721 line induced by X-ray and carbon ion irradiations was investigated.


METHODS
Human hepatoma SMMC-7721 cells were irradiated with a carbon ion beam and X-ray. Cell survival was determined by a standard colony-forming assay. STAT-3 protein expression was analysed by Western Immunoblots. Cell cycle and apoptosis were performed by flow cytometry.


RESULTS
The viability of SMMC-7721 cells decreased with increasing dose of the carbon ion beam, and the high-LET carbon ion beam led to the cells getting arrested at G(2)/M phase. Western Blot analyses show that STAT-3 expression increased with increasing radiation dose. The carbon ion irradiation induced cell apoptosis and significantly promoted the expression of STAT-3 gene compared with the X-ray irradiation. The apoptosis rate is correlated with the expression of STAT-3 in human hepatoma SMMC-7721 cells after exposure to different doses of X-ray and heavy ion beam.


CONCLUSIONS
Heavy ion irradiation increases the expression of STAT-3 gene, makes SMMC-7721 cells arrested at G(2)/M phase and increases cell apoptosis in comparison with that induced by low-LET X-ray. The STAT-3 expression may be regarded as a protected reaction when the cancerous cells suffer a strong stimulus such as high-LET irradiation. The interaction of STAT-3 expression and other cytokines in human hepatoma and the relationship between STAT-3 and radiation-induced apoptosis remain to be clarified in the future.
Ma
Jianxun
J
Department of General Surgery, The Peoples Hospital of Gansu Province, Lanzhou, People's Republic of China.
Ye
Lanping
L
Da
Mingxu
M
Wang
Xiaopeng
X
D017209:Apoptosis / Q000528:radiation effects*; D002244:Carbon; D045744:Cell Line, Tumor; D004307:Dose-Response Relationship, Radiation; D016195:G2 Phase / Q000528:radiation effects*; D063193:Heavy Ion Radiotherapy; D006801:Humans; D050796:STAT3 Transcription Factor / Q000096:biosynthesis / Q000528:radiation effects*; D014965:X-Rays
D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D002244:Carbon