Effect of cisplatin combined with X-ray irradiation on proliferation of human esophageal squamous cell cancer Eca109 cells and its mechanisms / 肿瘤研究与临床

ABSTRACT

Objective To investigate the effect of cisplatin combined with X-ray irradiation on the proliferation of human esophageal squamous cell cancer Eca109 cells and its mechanism. Methods Methyl thiazolyl tetrazolium (MTT) method was used to determine 10％ inhibitory concentration (IC10) and half inhibitory concentration (IC50) of Eca109 cells after 24 h treated with cisplatin in cisplatin group. Then the irradiation group was treated by 4 Gy 6 MV-X ray, cisplatin combined with X-ray irradiation group was treated with 4 Gy 6 MV-X ray irradiation, and IC10 or IC50 cisplatin treatment. After 24 h, 36 h and 48 h of culture, MTT method was used to detect the cell growth and inhibition in each group. Flow cytometry was used to detect cell cycle and apoptosis in each group. Results After 24 h for cisplatin treatment, IC10 and IC50 of Eca109 cells was 0.894 μg/ml and 8.654 μg/ml. After 24 h, 36 h and 48 h of culture, the inhibition rates of 4 Gy+IC10 group were (26.1 ±1.2)％, (56.4 ±4.0)％ and (75.1 ±3.2)％, respectively, and 4 Gy+IC50 group were (55.4±5.9)％, (84.7±3.1)％and (93.8±5.1)％, respectively, and irradiation group were (5.1±2.6)％, (12.2±1.3)％and (37.9±5.3)％, respectively. With the prolonged culture time, the inhibition rates of the three groups were increased gradually, and the differences were statistically significant (all P< 0.01); the inhibition rate of cisplatin combined with X-ray irradiation group was higher than that of irradiation group, and the differences were statistically significant (all P< 0.01). After 48 h of culture, the proportion of G2/M phase cells in the blank control group, irradiation group, 4 Gy+IC10 group, and 4 Gy+IC50 group was increased to (3.0 ±1.5)％, (10.4±0.8)％, (24.8±3.1)％ and (38.9±1.2)％, and the differences were statistically significant (F= 224.3, P<0.001); the proportion of S phase cells in 4 Gy+IC10 group and 4 Gy+IC50 group was (23.4±7.7)％ and (23.2± 5.2)％ respectively, which were lower than that in the blank control group [(44.5 ±2.0)％], and the differences were statistically significant (all P< 0.05). The apoptosis rate of 4 Gy+IC10 group and 4 Gy+IC50 group was (14.0±4.2)％ and (17.9±3.0)％, respectively, which was higher than that of the blank control group [(4.6± 1.8)％], and the differences were statistically significant (all P< 0.05); the apoptosis rate of 4 Gy+IC50 group was also higher than that of irradiation group [(7.1±0.9)％], and the difference was statistically significant (P=0.001). Conclusions Cisplatin combined with X-ray irradiation can significantly inhibit the proliferation of human esophageal squamous cell cancer Eca109 cells in a dose and time-dependent manner. The main mechanism may be related with the fact that low-dose or high-dose cisplatin and X-ray irradiation makes the Eca109 cells arrest at G2/M phase, so that the sensitivity of cells to irradiation can be increased.