Islam M S, Mitsuhashi N, Akimoto T, Sakurai H, Hasegawa M, Ishikawa H, Niibe H
Department of Radiology and Radiation Oncology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan.
Oncol Rep. 2001 May-Jun;8(3):501-7. doi: 10.3892/or.8.3.501.
We investigated cell susceptibility to hyperthermia-induced apoptosis in two rat yolk sac tumor cell lines (RYSTs) and attempted to correlate this with the known potentially relevant molecular determinants of apoptosis, p53 protein status, Bcl-2 family of proteins and heat shock proteins (Hsp). Parent cell line, NMT-1 (carrying wild-type p53 gene) was radiosensitive but thermoresistant compared to the variant cell line, NMT-1R (mutated type p53), which was isolated from NMT-1 by repeated radiation exposure. Induction of apoptosis by hyperthermia at 43 degrees C was morphologically detected in both RYSTs using hematoxylin and eosin, and TUNEL staining and additionally confirmed by DNA ladder formation (the cleavage of DNA into oligonucleosomal fragments). Western blot analysis showed an increase in expression of p53, p21WAF1/CIP1, Hsp70 proteins in both cell lines after heat-shock at 43 degrees C for 30 min. Hsp90 expression increased in NMT-1 but was not affected by heating in NMT-1R cells, whereas hyperthermia exerted no effect on the endogenous expression of Bax. Bcl-2 protein could not be detected in either RYST. These results suggest that hyperthermia induced apoptosis in both NMT-1 and NMT-1R and apoptosis in RYSTs may be independent of p53-dependent signaling pathway.
我们研究了两种大鼠卵黄囊瘤细胞系（RYSTs）对热诱导凋亡的细胞敏感性，并试图将其与已知的潜在相关凋亡分子决定因素、p53蛋白状态、Bcl-2蛋白家族和热休克蛋白（Hsp）相关联。亲本细胞系NMT-1（携带野生型p53基因）对辐射敏感，但与变异细胞系NMT-1R（p53突变型）相比对热有抗性，NMT-1R是通过反复辐射暴露从NMT-1中分离出来的。使用苏木精和伊红以及TUNEL染色在两种RYSTs中通过形态学检测到43℃热疗诱导的凋亡，并通过DNA梯带形成（DNA切割成寡核小体片段）进一步证实。蛋白质印迹分析显示，在43℃热休克30分钟后，两种细胞系中p53、p21WAF1/CIP1、Hsp70蛋白的表达均增加。Hsp90在NMT-1中的表达增加，但在NMT-1R细胞中不受加热影响，而热疗对Bax的内源性表达没有影响。在两种RYST中均未检测到Bcl-2蛋白。这些结果表明，热疗在NMT-1和NMT-1R中均诱导凋亡，并且RYSTs中的凋亡可能独立于p53依赖性信号通路。
