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A Low Membrane Hsp70 Expression in Tumor Cells With Impaired Lactate Metabolism Mediates Radiosensitization by NVP-AUY922

As overexpression and membrane localization of stress proteins together with high lactate levels promote radioresistance in tumor cells, we studied the effect of the Hsp90 inhibitor NVP-AUY922 on the cytosolic and membrane expression of heat shock proteins (HSPs) and radiosensitivity in murine melanoma (B16F10) and human colorectal (LS174T) wildtype (WT) and lactate dehydrogenases A/B double knockout (LDH-/-) tumor cells. Double knockout for LDHA/B has been found to reduce cytosolic as well as membrane HSP levels, whereas treatment with NVP-AUY922 stimulates the synthesis of Hsp27 and Hsp70, but does not affect membrane Hsp70 expression. Despite NVP-AUY922-inducing elevated levels of cytosolic HSP, radiosensitivity was significantly increased in WT cells and even more pronounced in LDH-/- cells. An impaired lipid metabolism in LDH-/- cells reduces the Hsp70 membrane-anchoring sphingolipid globotriaosylceramide (Gb3) and thereby results in a decreased Hsp70 cell surface density on tumor cells. Our results demonstrate that the membrane Hsp70 density, but not cytosolic HSP levels determines the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in LDH-/- cells.

Related Products

Cat.No. Product Name Information
S1069 Luminespib (NVP-AUY922) Luminespib (AUY-922, NVP-AUY922, VER-52296) is a highly potent HSP90 inhibitor for HSP90α/β with IC50 of 13 nM /21 nM in cell-free assays, weaker potency against the HSP90 family members GRP94 and TRAP-1, exhibits the tightest binding of any small-molecule HSP90 ligand. Luminespib (AUY-922, NVP-AUY922) effectively downregulates and destabilizes the IGF-1Rβ protein and results in growth inhibition, autophagy and apoptosis. Phase 2.

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Apoptosis related HSP (HSP90) IGF-1R Autophagy