Abstract 5426: Down-regulation of cancer metabolism enhances radiosensitivity by impairing the heat shock response

Abstract Therapy (radiation) resistance can, inter alia, be caused by an increased lactate dehydrogenase (LDH) activity, elevated concentrations of the oncometabolite lactate and an overexpression of anti-apoptotic heat shock proteins (HSPs). In this study we aimed to break radioresistance by targeting the cancer metabolism. We could show, for the first time, that the lactate metabolism and heat shock response are co-regulated in two cancer cell systems (murine B16F10 melanoma cells, human LS174T colorectal adenocarcinoma cells). A CRISPR/Cas9 induced double knockout of LDHA/B (LDH−/−) as well as a pharmacological inhibition of LDH by Oxamate or GNE-140 reduces tumor growth, ROS production and synthesis of different HSPs, including Hsp90, Hsp70 and Hsp27. Moreover, the membrane Hsp70 density was significantly reduced on tumor cells after inhibition of the LDH activity as a consequence of a down-regulated lipid metabolism affecting the Hsp70-anchoring, tumor-specific glycosphingolipid Gb3. Our results demonstrate that influencing cancer metabolism increases radiation sensitivity by an impairment of the stress response. Since presently available LDH inhibitors have a low stability and high toxicity in vivo, we are currently investigating more potent LDH inhibitors with a beneficial safety profile. In summary, targeting the lactate metabolism provides a promising strategy to improve radiosensitivity by impairing the stress response. Citation Format: Melissa Schwab, Katharina Thunborg, Omid Azimzadeh, Christine von Toerne, Maxim Shevtsov, Masa Zdralevic, Jacques Pouyssegur, Kathrin Renner, Marina Kreutz, Peter Vaupel, Gabriele Multhoff. Down-regulation of cancer metabolism enhances radiosensitivity by impairing the heat shock response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5426.