Modulation of Urinary Lipid Peroxidation Products in Breast Cancer and Design of Mimetic 4-HNE (4-HNEM) as SIRT2 Inhibitor

Background: Dysregulated metabolism, including lipid peroxidation, contributes to the various stages of breast cancer, including initiation and progression. However, 4-HNE mimetic as a new class of drugs of epigenetic enzymes is not explored. Objective: The objective of this study was to explore the relevance of lipid peroxidation products in breast cancer and the design of mimetic 4-HNE as an inhibitor of SIRT2. Methods: The metabolite profiling of 4-HNE was collected from the urine of breast cancer patients and healthy subjects by employing an in-house developed vertical tube gel electrophoresis (VTGE) tool and LC-HRMS. The determination of lipid peroxidation products MDA was estimated by thiobarbituric acid-reactive substance (TBARS) assay. Mimetic 4-HNE (4-HNEM) was designed and evaluated for their inhibitory binding affinity upon a potential target SIRT2 using molecular docking and molecular dynamics (MD) simulations. Results: Metabolic profiling of 4-HNE indicated detectable levels in the urine of breast cancer patients over non-detectable levels in healthy subjects. Also, the level of TBARS MDA appeared to be reduced in the urine of breast cancer patients over healthy control. Computational tool-assisted molecular docking-based screening data predicted that 4-HNE has a good inhibitory binding affinity (-7.0 kcal/mol) upon SIRT2. Furthermore, the designed mimetic 4-HNEM projected an improved inhibitory binding affinity (-8.7 kcal/mol) against SIRT2. Furthermore, mimetic 4-HNEM exhibited equivalent strong binding affinity and specific interacting amino acid residues (ARG97, PHE119, ALA186, PHE234, PHE235) similar to a known SIRT2 inhibitor 8NO. ADMET profiles of 4-HNEM, including drug-induced liver injury and cytotoxicity, were found to be slightly better than a known SIRT2 inhibitor 8NO. Conclusion: This study emphasizes the relevance of 4-HNE and MDA as biomarkers in breast cancer. A mimetic 4-HNEM is projected to be a novel small-molecule inhibitor of SIRT2 that could be explored as a potential combinatorial anticancer agent.