Meshalkina Darya A, Shevtsov Maxim A, Dobrodumov Anatoliy V, Komarova Elena Y, Voronkina Irina V, Lazarev Vladimir F, Margulis Boris A, Guzhova Irina V
Institute of Cytology of Russian Academy of Sciences, St. Petersburg 194064, Russia.
First I.P. Pavlov State Medical University of St. Petersburg, St. Petersburg 197022, Russia.
Oncotarget. 2016 Apr 19;7(16):22050-63. doi: 10.18632/oncotarget.7872.
The chaperone system based on Hsp70 and proteins of the DnaJ family is known to protect tumor cells from a variety of cytotoxic factors, including anti-tumor therapy. To analyze whether this also functions in a highly malignant brain tumor, we knocked down the expression of Hsp70 (HSPA1A) and its two most abundant co-chaperones, Hdj1 (DNAJB1) and Hdj2 (DNAJA1) in a C6 rat glioblastoma cell line. As expected, tumor depletion of Hsp70 caused a substantial reduction in its growth rate and increased the survival of tumor-bearing animals, whereas the reduction of Hdj1 expression had no effect. Unexpectedly, a reduction in the expression of Hdj2 led to the enhanced aggressiveness of the C6 tumor, demonstrated by its rapid growth, metastasis formation and a 1.5-fold reduction in the lifespan of tumor-bearing animals. The in vitro reduction of Hdj2 expression reduced spheroid density and simultaneously enhanced the migration and invasion of C6 cells. At the molecular level, a knock-down of Hdj2 led to the relocation of N-cadherin and the enhanced activity of metalloproteinases 1, 2, 8 and 9, which are markers of highly malignant cancer cells. The changes in the actin cytoskeleton in Hdj2-depleted cells indicate that the protein is also important for prevention of the amoeboid-like transition of tumor cells. The results of this study uncover a completely new role for the Hdj2 co-chaperone in tumorigenicity and suggest that the protein is a potential drug target.
基于热休克蛋白70（Hsp70）和DnaJ家族蛋白的伴侣系统已知可保护肿瘤细胞免受多种细胞毒性因子的影响，包括抗肿瘤治疗。为了分析这在高度恶性的脑肿瘤中是否也起作用，我们在C6大鼠胶质母细胞瘤细胞系中敲低了Hsp70（HSPA1A）及其两种最丰富的共伴侣蛋白Hdj1（DNAJB1）和Hdj2（DNAJA1）的表达。正如预期的那样，Hsp70的肿瘤缺失导致其生长速率大幅降低，并延长了荷瘤动物的生存期，而Hdj1表达的降低则没有影响。出乎意料的是，Hdj2表达的降低导致C6肿瘤的侵袭性增强，表现为其快速生长、转移形成以及荷瘤动物寿命缩短1.5倍。体外降低Hdj2表达降低了球体密度，同时增强了C6细胞的迁移和侵袭能力。在分子水平上，敲低Hdj2导致N-钙黏蛋白重新定位，并增强了金属蛋白酶1、2、8和9的活性，这些都是高度恶性癌细胞的标志物。Hdj2缺失细胞中肌动蛋白细胞骨架的变化表明，该蛋白对于预防肿瘤细胞的阿米巴样转变也很重要。本研究结果揭示了Hdj2共伴侣蛋白在肿瘤发生中的全新作用，并表明该蛋白是一个潜在的药物靶点。
