Knock-down of Hdj2/DNAJA1 co-chaperone results in an unexpected burst of tumorigenicity of C6 glioblastoma cells

Abstract

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.

Discovery and optimization of cardenolides inhibiting HSF1 activation in human colon HCT-116 cancer cells

“…The reduction of chaperones expression was correlated with the diminished cell growth rate (Figure 2F ). This phenomenon is a well-known characteristic of cancer cells depleted of the HSR [ 16 , 17 ]. Moreover, the flow cytometry data showed that the growth of a considerable portion of the population of HCT-116 cells stopped at the phase G0/G1 (Figure 2G ), suggesting that, taken alone, the compound possesses growth inhibitory activity, as do most of the other pharmacological inhibitors of HSR, exemplified by KRIBB11 [ 18 ].…”

“…Primary mouse monoclonal anti-Hsp70 (Clone 2H9) and anti-Hsp40 (Clone J32) antibodies were produced previously in our laboratory [ 16 , 29 ]. Mouse monoclonal anti-GAPDH (Clone 6C5) antibodies were kindly provided by Prof. Vladimir Muronetz (Moscow State University, Russia).…”

Sensitizing tumor cells to conventional drugs: HSP70 chaperone inhibitors, their selection and application in cancer models

“…To determine whether AEAC is able to elevate antitumor capacity of doxorubicin, we used two animal models: mouse melanoma B16 growing subcutaneously and the intracranial rat C6 glioblastoma 15 – 17 . After tumor cell inoculation and treatment with doxorubicin alone or in combination with AEAC (see Materials and Methods for details), we measured tumor size in B16-bearing mice on the day 20 after tumor grafting.…”

Molecular subtyping of glioblastoma based on immune-related genes for prognosis

“…Nine of these 14 genes were previously suggested to be involved in malignant transformation, pathogenesis, progression, and immune microenvironment of GBM, including S100A9, HSPA1A, GALR2, EDNRB, IL13RA2, ELN, NR1D1, HDGF, and MET [30][31][32][33][34][35] . They were markedly correlated with patient survival and prognosis, which means that our bioinformatic mining displayed a high reliability and accuracy.…”