Geldanamycin-Induced Osteosarcoma Cell Death Is Associated with Hyperacetylation and Loss of Mitochondrial Pool of Heat Shock Protein 60 (Hsp60)

Abstract

Osteosarcoma is one of the most malignant tumors of childhood and adolescence that is often resistant to standard chemo- and radio-therapy. Geldanamycin and geldanamycin analogs have been recently studied as potential anticancer agents for osteosarcoma treatment. Here, for the first time, we have presented novel anticancer mechanisms of geldanamycin biological activity. Moreover, we demonstrated an association between the effects of geldanamycin on the major heat shock proteins (HSPs) and the overall survival of highly metastatic human osteosarcoma 143B cells. We demonstrated that the treatment of 143B cells with geldanamycin caused a subsequent upregulation of cytoplasmic Hsp90 and Hsp70 whose activity is at least partly responsible for cancer development and drug resistance. On the other hand, geldanamycin induced upregulation of Hsp60 gene expression, and a simultaneous loss of hyperacetylated Hsp60 mitochondrial protein pool resulting in decreased viability and augmented cancer cell death. Hyperacetylation of Hsp60 seems to be associated with anticancer activity of geldanamycin. In light of the fact that mitochondrial dysfunction plays a critical role in the apoptotic signaling pathway, the presented data may support a hypothesis that Hsp60 can be another functional part of mitochondria-related acetylome being a potential target for developing novel anticancer strategies.

Doxorubicin anti-tumor mechanisms include Hsp60 post-translational modifications leading to the Hsp60/p53 complex dissociation and instauration of replicative senescence

“…Loss of Hsp60 functions in a cancer cell, probably as a consequence of hyperacetylation for example after doxorubicin treatment, could lead to proteotoxic stress ultimately resulting in the switch of pro-survival signaling to cell-proliferation arrest. Our results are consistent with previous data demonstrating that hyperacetylation of Hsp60 was associated with anticancer activity of geldanamycin in osteosarcoma derived cells [32]. Hsp60 is one of the proteins that undergo acetylation in U2OS OS cells with sirtuin 3 (Sirt3) knockout [57].…”

“…Immunofluorescence was performed as described previously [32]. NCI-H292 cells were placed in 8-well microscope chamber slide at the density of 10,000 cells/well, cultured for 24 h and then treated with doxorubicin.…”

The dissociation of the Hsp60/pro-Caspase-3 complex by bis(pyridyl)oxadiazole copper complex ( CubipyOXA ) leads to cell death in NCI-H292 cancer cells

“…These findings suggest that the reduction of Hsp60 levels might have various causes, as it has been already demonstrated, in which Hsp60 could be tagged by post-translational modifications, such as hyperacetylation and ubiquitination. This could regulate the degradation of the chaperone by the ubiquitin-proteosome system [12,55]. Otherwise, the post-translational modifications could constitute a signal for extracellular secretion through the lipid raft pathway [11,49,56].…”

“…The function of extracellular Hsp60 is still under discussion. For instance, it may mediate interactions with the immune cells and other body tissues and alter the tumor microenvironment [11,12,55,57].…”

“…Our recent studies have shown that the induction of stress on cancer cells affects the Hsp60 levels [6,11,12] and it is known that this chaperone plays a crucial role in apoptosis. Furthermore, we found that Hsp60 interacts with Pro-Caspase-3 (pC3) in the mucoepidermoid carcinoma cell line NCI-H292 and this association persists after the induction of oxidative stress [5].…”