Laboratory of Biology of Recognition, Universidade Estadual do Norte Fluminense, av. Alberto Lamego 2000, Campos, Rio de Janeiro, Brazil.
APMIS. 2010 Mar;118(3):179-87. doi: 10.1111/j.1600-0463.2009.02576.x.
Heat shock protein 70 kDa, Hsp70, is an important intracellular factor that protects cells from stress. Unusual plasma membrane expression of Hsp70, observed in some cancer cells, contributes to the cell's recognition and elimination by the immune system. Induction of apoptosis in cancer cells was demonstrated to increase Hsp70 translocation to the surface membrane, enhancing immunogenic effects through the stimulation of dendritic cells. As hyperthermia is proposed as a method of choice for anti-cancer therapy, we examined whether apoptosis induction by heat shock enhances Hsp70 membrane translocation in U-937 leukaemia cells. Cells were exposed to sub-lethal heat shock, and intracellular and membrane-bound Hsp70 expression was evaluated in apoptotic and viable cell sub-populations, employing flow cytometry and immunofluorescence. Heat shock induced Hsp70 membrane translocation in the viable cells that were able to enhance Hsp70 production upon heating, but not in the cells undergoing apoptosis that continued to express low basal levels of the intracellular protein. Data suggest that the protein translocation was associated with the increasing Hsp70 content rather than the apoptotic process. Apoptosis does not contribute to externalization of Hsp70, at least in the cells with low levels of this protein.
热休克蛋白 70kDa，Hsp70，是一种重要的细胞内因子，可保护细胞免受压力。在一些癌细胞中观察到的 Hsp70 异常的质膜表达有助于细胞被免疫系统识别和清除。已经证明诱导癌细胞凋亡会增加 Hsp70 向质膜的易位，通过刺激树突状细胞增强免疫原性效应。由于高温被提议作为癌症治疗的首选方法，我们研究了热休克诱导的细胞凋亡是否增强 U-937 白血病细胞中的 Hsp70 膜易位。将细胞暴露于亚致死性热休克下，并通过流式细胞术和免疫荧光评估凋亡和存活细胞亚群中的细胞内和膜结合 Hsp70 表达。热休克诱导了存活细胞的 Hsp70 质膜易位，这些细胞能够在加热时增强 Hsp70 的产生，但不会在继续表达低基础水平细胞内蛋白的凋亡细胞中发生。数据表明，蛋白易位与 Hsp70 含量的增加有关，而与凋亡过程无关。凋亡至少不会导致 Hsp70 的外排，至少在这种蛋白水平较低的细胞中是这样。
