Characterization of HSP90 and novel isoform-specific TRAP-1 inhibitors

Abstract

[EN] Cancer is one of the main causes of death worldwide. Therefore, cancer research is essential to improve the diagnosis and treatment of patients. Nowadays novel cancer therapies include the identification of molecular targets that promote malignant cells to adapt to environmental stress. This thesis has two aims. First, to characterize non-isoform specific HSP90 inhibitors PU-H71, STA-9090, and HSP990 by analyzing U2OS (human osteosarcoma epithelial) cell survival with CCK8 assay and HSF1, HSF2, HSP70, β-tubulin, and p53 expression, in a way to understand the inhibitory effect in U2OS cell viability and cytotoxicity, HSR induction and client protein stability. Related to this, we wanted to optimize the CCK8 assay in U2OS for future applications.

Second, to characterize isoform-specific novel TRAP-1 inhibitors, which might be a promising alternative to minimize the toxicity of non-isoform-selective inhibitors. This will be done by analyzing U2OS wild-type (WT), HSF1 knockout (KO), and HSF2 KO cell viability and HSR induction in inhibitory conditions. Cells lacking HSF1 and HSF2 will allow us to understand these proteins’ function and cytotoxic effect during their absence and to know if WT and KO cells are equally sensitive to TRAP-1 inhibitors. We hypothesized that TRAP-1inhibitors should not induce HSR as they do not target all HSP90 isoforms. At the same time, we hypothesized that KO cells would be more sensitive than WT cells to TRAP-1 inhibitors, being HSF1 KO cells the most sensitive ones, as seen in Bagatell et al., 2000 and Joutsen et al., 2020, and because HSF1 is the major regulator of the cytoprotective HSR.