Investigation on nitroalkylation as a novel endogenous regulatory mechanism and therapeutic strategy to modulate the ubiquitin proteasome system

• Applicant: Jessica Roos, Ph.D.
• Subject Area: Pharmacology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 513560451

Nitro fatty acids (NFA) are highly potent, anti-inflammatory and cytoprotective lipid derivatives, generated endogenously in humans during inflammatory processes. Notably, well tolerated NFA successfully passed clinical phase I trials and are currently evaluated in clinical phase II studies for the treatment of i.e. primary focal segmental glomerulosclerosis. NFA exert their anti-inflammatory and protective actions primary via nitroalkylation of i.e. pro-inflammatory proteins such as NF-kB or 5-lipoxygenase. In a previous publication (Kühn et al. 2018), we could demonstrate that NFA are potent tumor suppressive agents, which are able to inhibit the cell growth of colorectal carcinoma cells (CRC) under in-vitro and in-vivo conditions. However, we were not able to identify the exact molecular target. Further studies revealed the ubiquitin-proteasome system (UPS) as a novel target of NFA. Prolonged proteasome inhibition can lead to the activation or inhibition of different signaling pathways, resulting in apoptosis induction. Thus, targeting the UPS could be a possible explanation for the observed tumor suppressive effects of NFA. Beyond the NFA-mediated antineoplastic effects, nitroalkylation could also be a novel regulatory mechanism of the UPS, which could be used to identify new approaches for the inhibition of the UPS. The objective of this funding application is to characterize the effect of NFA and new synthesized NFA derivatives on the UPS (aim 1 and 2), to elucidate the structural requirements of the UPS inhibition (aim 2) and to further analyze their therapeutic potential as possible drug-candidates for the treatment of malignant diseases (aim 3). For the implementation of aim 1, we apply biochemical as well as mass spectrometric analyses. We decided to work with these two parallel approaches to guarantee a successful identification of the molecular target responsible for the tumor suppressive properties of NFA. For the structural activity relationship study we plan to systematically modify the Michael acceptor moiety, the carboxyl- and ω-end of the fatty acid backbone to create a diverse set of NFA derivatives and mimetics who will be analyzed for their UPS-inhibitory and antineoplastic activity To validate the importance of the UPS inhibition under in-vivo condition a Tumor Xenograft model with CRC is planned (aim 3a). The second part of aim 3 (aim 3b) focusses on the investigation of the therapeutic potential of NFA and/or NFA derivatives/mimetics. Thus, selected tumor subtypes will be studied under in-vitro and in-vivo conditions for their sensitivity against NFA treatment in comparison to the approved proteasome inhibitors (PIs).

• DFG Programme: Research Grants