Institute of Cytology of the Russian Academy of Sciences, 194064 St. Petersburg, Russia.
InterBioscreen, 142432 Chernogolovka, Russia.
Int J Mol Sci. 2021 Feb 3;22(4):1520. doi: 10.3390/ijms22041520.
Hypoxia, which commonly accompanies tumor growth, depending on its strength may cause the enhancement of tumorigenicity of cancer cells or their death. One of the proteins targeted by hypoxia is glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and we demonstrated here that hypoxia mimicked by treating C6 rat glioblastoma cells with cobalt chloride caused an up-regulation of the enzyme expression, while further elevation of hypoxic stress caused the enzyme aggregation concomitantly with cell death. Reduction or elevation of GAPDH performed with the aid of specific shRNAs resulted in the augmentation of the tumorigenicity of C6 cells or their sensitization to hypoxic stress. Another hypoxia-regulated protein, Hsp70 chaperone, was shown to prevent the aggregation of oxidized GAPDH and to reduce hypoxia-mediated cell death. In order to release the enzyme molecules from the chaperone, we employed its inhibitor, derivative of colchicine. The compound was found to substantially increase aggregation of GAPDH and to sensitize C6 cells to hypoxia both in vitro and in animals bearing tumors with distinct levels of the enzyme expression. In conclusion, blocking the chaperonic activity of Hsp70 and its interaction with GAPDH may become a promising strategy to overcome tumor resistance to multiple environmental stresses and enhance existing therapeutic tools.
缺氧通常伴随着肿瘤的生长，其强度可能导致癌细胞的致瘤性增强或死亡。受缺氧影响的蛋白质之一是甘油醛-3-磷酸脱氢酶（GAPDH），我们在这里证明，用氯化钴处理大鼠 C6 神经胶质瘤细胞来模拟缺氧会引起酶表达的上调，而进一步增加缺氧应激会导致酶聚集，同时伴随着细胞死亡。借助特异性 shRNA 降低或升高 GAPDH 的表达水平会导致 C6 细胞的致瘤性增强或对缺氧应激的敏感性增加。另一种受缺氧调节的蛋白质，热休克蛋白 70 伴侣，被证明可以防止氧化 GAPDH 的聚集，并减少缺氧介导的细胞死亡。为了将酶分子从伴侣中释放出来，我们使用了它的抑制剂，秋水仙碱衍生物。该化合物被发现可以显著增加 GAPDH 的聚集，并在体外和体内具有不同酶表达水平的肿瘤动物中增加 C6 细胞对缺氧的敏感性。总之，阻断热休克蛋白 70 的伴侣活性及其与 GAPDH 的相互作用可能成为克服肿瘤对多种环境应激的抵抗并增强现有治疗工具的有前途的策略。
