Effect of H2AX silence on radiosensitivity of esophageal cancer ECA109 cell xenograft in nude mice / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the effects of silencing H2AX gene on esophageal cancer ECA109 cell xenograft growth and sensitivity to radiotherapy in nude mice.Methods BALB/c nude mice models were established by subcutaneously inoculating differently treated ECA109 cells into nude mice.By random number table method 60 nude mice were divided into six groups,including blank group,irradiation group,negative group,negative with irradiation group,silence group and silence with irradiation group.The nude mice were irradiated with 15 Gy of 6 MV X-rays 21 d after inoculation.After irradiation 48 h,half of each mice group was terminated.The tumor specimens were processed by Western blot,RT-PCR and flow cytometry were used to detect the change in protein levels,RNA levels,and cell cycle.Results The tumor volume was (42.76 ±4.40) mm3 in silence group,significantly smaller than that of the blank group (73.18±8.80) mm3 and the negative group(71.27 ±8.40) mm3(F=67.8,P＜0.01).H2AX protein expression level in the silence group was also significantly lower (0.12 ±0.03 vs.1.12 ±0.11,1.16 ± 0.08,F =34.27,P ＜ 0.01).Relative H2AX mRNA expression level in the silence group was (0.85 ± 0.31),significantly lower than that of the blank group (1.86 ± 0.26) and the negative group (1.82 ±0.24,F =39.45,P ＜ 0.01).Co-immunoprecipitation assay showed that γ-H2AX and MDC1,53BP1 obvious interaction after irradiation,which would be weakened through silencing H2AX.The tumor volumes at different groups had significant difference after irradiation (F =13.56,P ＜ 0.01).The apoptosis rate in the silence group was significantly higher than that of the blank group and the negative group [(24.15±2.25) ％ vs.(13.26±1.54) ％,(12.78±1.47) ％ (F=54.33,P＜0.01)].G2/M phase arrested in the silence with irradiation group lower than that of the radiation group (F =10.21,P ＜ 0.01).Conclusions Silencing H2AX gene expression could inhibit the growth of esophageal cancer ECA109 cell xenograft and increase the radiosensitivity of tumor.