Min Feng-Ling, Zhang Hong, Li Wen-Jian, Gao Qing-Xiang, Zhou Guang-Ming
Institute of Modern Physics, Chinese Academy of Science, Lanzhou, Gansu province 730000, People's Republic of China.
In Vitro Cell Dev Biol Anim. 2005 Sep-Oct;41(8-9):284-8. doi: 10.1290/0505029R.1.
We investigated the effect of exogenous wild-type p53 on the radiation-induced cells apoptosis and necrosis at different levels of linear energy transfer (LET) to evaluate its mechanisms. The human melanoma cell line A375, which bears wild-type p53 gene status, was used, as well as the transfectant A375 cells (A375/p53) with adenoviral vector containing the wild-type p53 gene. We exposed these cells to X-rays and to accelerated carbon-ion (C-) beams. Cellular sensitivities were determined by using clonogenic assay. Apoptotic and necrotic cell deaths were determined morphologically by dual staining (acridine orange and ethidium bromide) using fluorescence microscopy. We discovered that (1) there was no significant difference in survival fraction between A375 cells and A375/p53 cells irradiated by C-beams with greater than 32 KeV/microm LET, (2) although apoptosis in the two kinds of cells increased in an LET-dependent manner, exogenous wild-type P53 induced cell apoptosis efficiently in A375/p53 relative to A375 cells with X-rays or high-LET irradiation, and (3) by high-LET irradiation, the number of necrosis in A375 cells increased significantly (P < 0.05) in comparison with A375/p53 cells. These results indicate that in high-LET irradiation apoptosis induction is p53 dependent partly and exogenous wild-type P53 plays an important role in modulating cell death type, although there was no significant difference in cellular radiosensitivities. Our observation in the study offers the potential application of high-LET radiation combined with p53 in the management of human patients with melanoma.
我们研究了外源性野生型p53在不同线性能量传递（LET）水平下对辐射诱导的细胞凋亡和坏死的影响，以评估其机制。使用了具有野生型p53基因状态的人黑色素瘤细胞系A375，以及含有野生型p53基因的腺病毒载体转染的A375细胞（A375/p53）。我们将这些细胞暴露于X射线和加速碳离子（C-）束中。通过克隆形成试验确定细胞敏感性。使用荧光显微镜通过双重染色（吖啶橙和溴化乙锭）从形态学上确定凋亡和坏死细胞死亡。我们发现：（1）LET大于32 KeV/μm的C束照射下，A375细胞和A375/p53细胞的存活分数没有显著差异；（2）尽管两种细胞中的凋亡均以LET依赖性方式增加，但相对于接受X射线或高LET照射的A375细胞，外源性野生型P53在A375/p53中有效地诱导了细胞凋亡；（3）通过高LET照射，与A375/p53细胞相比，A375细胞中的坏死数量显著增加（P<0.05）。这些结果表明，在高LET照射下，凋亡诱导部分依赖于p53，并且外源性野生型P53在调节细胞死亡类型中起重要作用，尽管细胞放射敏感性没有显著差异。我们在该研究中的观察结果为高LET辐射与p53联合应用于人类黑色素瘤患者的治疗提供了潜在应用。
