Repositioning of FDA-Approved antifungal agents to interrogate Acyl-CoA synthetase long chain family member 4 (ACSL4) in ferroptosis.

Ferroptosis, first coined in 2012, is an iron-dependent regulated cell death (RCD) characterized by the accumulation of lipid peroxides to toxic levels. This mechanism is currently being evaluated as a target for a variety of diseases offering new opportunities for drug design and development. Recent reports uncovered acyl-CoA synthetase long-chain 4 (ACSL4) as a critical contributor to ferroptosis execution. Therefore, ACSL4 inhibitors are emerging as attractive anti-ferroptotic agents. Herein, we developed a robust screening cascade with orthogonal biophysical and biochemical techniques to identify original human ACSL4 inhibitors. By screening an FDA-approved drug library, we were able to identify and validate new inhibitors with micromolar-range activities against ACSL4. With an IC50 of 280 nM against hACSL4, antifungal agent sertaconazole is to our knowledge, the most potent ACSL4 inhibitor identified so far. In addition, sertaconazole significantly reduced lipid peroxidation and ferroptosis in human differentiated dopaminergic neurons (Lund human mesencephalic LUHMES cells), demonstrating that it is a valuable chemical tool for further investigating the role of ACSL4 in ferroptosis. This study highlights the phenethyl-imidazole scaffold as a novel and promising starting point for the development of anti-ferroptotic agents targeting ACSL4.

Anti-alcohol abuse drug disulfiram inhibits human PHGDH via disruption of its active tetrameric form through a specific cysteine oxidation.

Due to rising costs and the difficulty to identify new targets, drug repurposing appears as a viable strategy for the development of new anti-cancer treatments. Although the interest of disulfiram (DSF), an anti-alcohol drug, to treat cancer was reported for many years, it is only very recently that one anticancer mechanism-of-action was highlighted. This would involve the inhibition of the p97 segregase adaptor NPL4, which is essential for the turnover of proteins involved in multiple regulatory and stress-response intracellular pathways. However, recently DSF was also reported as one of the first phosphoglycerate dehydrogenase (PHGDH) inhibitors, a tetrameric enzyme catalyzing the initial step of the serine synthetic pathway that is highly expressed in numerous cancer types. Here, we investigated the structure-activity relationships (SAR) of PHGDH inhibition by disulfiram analogues as well as the mechanism of action of DSF on PHGDH via enzymatic and cell-based evaluation, mass spectrometric and mutagenesis experiments.

Challenges and Opportunities in the Development of Serine Synthetic Pathway Inhibitors for Cancer Therapy.

Recent advances in the understanding of the relationship between cancer and metabolism have highlighted the relevance of the serine synthetic pathway (SSP), which consists of three successive enzymatic reactions. Enzymes of the SSP, such as phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase 1 (PSAT-1), were recently highlighted because they are amplified in a significant subset of human tumors, and their suppression by RNAi caused a decrease in cancer cell survival and growth. Currently, the discovery of drugs that inhibit these enzymes is still in its infancy, and the identification of suitable inhibitors could serve to understand the emerging biology of these metabolic enzymes. In this review, we present the SSP as a significant and novel emerging area for medicinal chemistry and we provide an overview of one of the key enzymes of the pathway, PHGDH.