Rödel Claus, Haas Joachim, Groth Anke, Grabenbauer Gerhard G, Sauer Rolf, Rödel Franz
Department of Radiation Oncology, University of Erlangen, Erlangen, Germany.
Int J Radiat Oncol Biol Phys. 2003 Apr 1;55(5):1341-7. doi: 10.1016/s0360-3016(02)04618-7.
Spontaneous apoptosis has been shown to predict tumor response to radiochemotherapy in rectal cancer in vivo. It remains to be elucidated, however, which genetic profile determines whether a tumor is more or less prone to apoptosis. Recently, a novel member of the inhibitor of apoptosis protein family, designated survivin, was identified. We investigated the impact of survivin expression on tumor cell apoptosis in three colorectal cell lines of different intrinsic radiosensitivities.
Survivin protein expression was measured by Western blot analysis, and survivin mRNA expression by quantitative TaqMan reverse transcription polymerase chain reaction, both in untreated cell and after irradiation with 2 and 8 Gy. The expression profile was then correlated to spontaneous and radiation-induced apoptosis (Tunel-Assay, DAPI-staining) in three colorectal cell lines of low (SW 480), intermediate (HCT-15), and high radiosensitivity (SW 48), as determined by the colony-forming assay.
In vitro analysis revealed higher spontaneous and higher radiation-induced apoptosis rates in the radiosensitive line (SW 48), as compared with the more resistant line (SW 480). In Western blot analysis and in TaqMan analysis, SW 480 was characterized by a higher spontaneous expression and a pronounced induction of survivin 48 h after irradiation, whereas survivin expression was low when untreated and not increased after irradiation in the most radiosensitive line SW 48. HCT-15 was intermediate, both with respect to the level of survivin mRNA and protein expression.
The inverse correlation of survivin-expression with spontaneous and radiation-induced apoptosis suggests that survivin is an important inhibitor of apoptosis in colorectal cancer cell lines. Analysis of survivin mRNA or protein expression may therefore provide predictive information on radio- and chemoresistance of individual colorectal tumors.
在直肠癌体内研究中，自发凋亡已被证明可预测肿瘤对放化疗的反应。然而，哪种基因谱决定肿瘤对凋亡的易感性高低仍有待阐明。最近，凋亡抑制蛋白家族的一个新成员——生存素被鉴定出来。我们研究了生存素表达对三种不同内在放射敏感性的结肠直肠癌细胞系中肿瘤细胞凋亡的影响。
通过蛋白质免疫印迹分析检测生存素蛋白表达，通过定量TaqMan逆转录聚合酶链反应检测生存素mRNA表达，检测对象为未处理的细胞以及接受2 Gy和8 Gy照射后的细胞。然后将表达谱与通过集落形成试验确定的低放射敏感性（SW 480）、中等放射敏感性（HCT - 15）和高放射敏感性（SW 48）的三种结肠直肠癌细胞系中的自发凋亡和辐射诱导凋亡（Tunel检测、DAPI染色）进行关联分析。
体外分析显示，与放射抗性较高的细胞系（SW 480）相比，放射敏感细胞系（SW 48）具有更高的自发凋亡率和辐射诱导凋亡率。在蛋白质免疫印迹分析和TaqMan分析中，SW 480的特征是具有较高的自发表达，且在照射后48小时生存素明显诱导表达，而在放射敏感性最高的细胞系SW 48中，未处理时生存素表达较低，照射后也未增加。HCT - 15在生存素mRNA和蛋白表达水平方面处于中间状态。
生存素表达与自发凋亡和辐射诱导凋亡呈负相关，这表明生存素是结肠直肠癌细胞系中一种重要的凋亡抑制剂。因此，分析生存素mRNA或蛋白表达可能为个体结肠直肠肿瘤的放射和化学抗性提供预测信息。
