放射抗拒的肺腺癌A549细胞端粒酶活性与放射敏感性的关系

Association of telomerase activity and radiosensitivity in A549 lung adenocarcinoma cell of tine tolerated to radiation

目的检测经过不同剂量的射线照射后人肺腺癌A549细胞存活后代的生长特性以及端粒酶的活性,探讨端粒酶与放射敏感性的关系。方法将同源的人肺腺癌A549细胞分为5组,分别给予0Gy、2 Gy、4 Gy、8 Gy、12 Gy的X射线照射,建立不同剂量的放射耐受模型,用TRAP-ELISA试剂盒检测A549组、A549-2组、A549-4组、A549-8组、A549-12组的端粒酶活性,用RT-PCR检测其端粒酶逆转录酶的相对表达含量,克隆形成实验检测其放射敏感性。结果经过不同剂量照射后的A549组,A549-2组,A549-4组,A549-8组的端粒酶活性分别为1.130±0.023,1.303±0.048,1.620±0.026,1.953±0.063,4组间的差异具有统计学意义(P<0.05),但A549-12组的端粒酶活性明显降低,为0.970±0.042,与以上4组的端粒酶活性差异具有统计学意义(P<0.05)。A549组、A549-2组、A549-4组、A549-8组的h TERT mRNA的相对表达含量分别为0.41±0.02,0.56±0.04,0.69±0.03,0.82±0.05,表达含量明显升高,且4组间的差异具有统计学意义(P<0.05);但A549-12组的h TERT mRNA的相对表达含量明显降低,为0.23±0.02,与以上4组h TERT mRNA的相对表达含量具有统计学意义(P<0.01)。5组细胞的放射敏感性随着放射剂量的增高而逐渐降低。A549组、A549-2组、A549-4组、A549-8组的端粒酶活性与其放射敏感性呈负相关(P<0.01),以上4组h TERT mRNA的相对表达含量与放射敏感性呈负相关(P<0.01)。结论在一定的剂量范围内,经过不同剂量的射线照射后形成的放射抗拒的人肺腺癌A549细胞系,其端粒酶活性、h TERT mRNA的相对表达含量与放射敏感性存在一定的相关性。

Objective To investigate the relationship of the telomerase activity and radiosensi- tivity of surviving progeny from different doses irradiated A549 lung ldenocarcinoma cell line. Methods The A549 cells were irradiated with 0 Gy, 2 Gy, 4 Gy, 8 Gy, 12 Gy of X-ray for three times and the surviving progeny were subcuhured. There were five groups： A549 group, A549-2 group, A549-4 group, A549-8 group and A549-12 group. The telomerase activity was measured by the polymerase chain reaction-based telomeric repeat amplification protocol cou- pled with ELISA. And the expression of the hTERT mRNA were detected by the RT-PCR as- say. The radiosensifivity index was examined by clone formation assay. Results The A549 cells were treated by different doses of irradiation. The telomerase activity of A549 group, A549-2 group, A549-4 group and A549-8 group were 1. 130 ±0. 023, 1. 303±0. 048, 1. 620± 0. 026, 1. 953 ± 0. 063 and the expression of hTERT mRNA was increased with the irradia- tion dose and was 0. 41 ± 0. 02, 0. 56 ± 0. 04, 0. 69 ± 0. 03, 0. 82± 0. 05. Each group had sig- nificant differences among the survival progenies （ P 〈 0. 05 ）. But the A549-12 group was 0. 970 ±0. 042 and 0. 23 ±0. 02 significantly reduced. Each group＇ s radiosensitivity was de- clined with the different irradiation dose. The telomerase activity and the expression of the hTERT mRNA was negatively correlated with radiosensitivity of each group （P 〈0. 01 ）. Con- clusion After different dose of irradiation, the radiosensitivity of the surviving progeny corre- lates with the telomerase activity and the expression of hTERT.