Design, Synthesis, Biological Evaluation, and Molecular Modeling Studies of Novel 2‐Aminothiazole Derivatives as Potential FOXM1 Inhibitors for Triple‐Negative Breast Cancer Therapy and Structure‐Activity Relationship

Triple Negative Breast Cancer (TNBC) is one of the most aggressive subtypes of breast cancer (BC), which is associated with a very poor prognosis. It is a broad category of tumors with a variety of biological, clinical, and morphological characteristics. FOXM1 is a pivotal transcription factor that modulates proliferation-associated genes through complex protein-DNA and protein-protein interactions, making it a highly attractive target in cancer therapy. However, existing small-molecule inhibitors often suffer from limited specificity and efficacy. In this study, we designed, synthesized, and evaluated novel series of 2-aminothiazole derivatives (C1-C15) as potential FOXM1 inhibitors. Molecular docking and molecular dynamics (MD) simulations were employed to investigate the binding interactions of these compounds with the FOXM1 DNA-binding domain (FOXM1-DBD). Structural analysis highlighted the importance of crucial residues, including Asn283, His287, and Arg286, in mediating inhibitory activity. Among the synthesized compounds, C11 exhibited remarkable structural alignment and interaction patterns with FOXM1-DBD, comparable to the reference inhibitor FDI-6. In vitro studies using TNBC cell lines (MDA-MB-231, BT-549, and BT-20) demonstrated that compound C11 significantly outperformed FDI-6 in potency. Western blot analysis revealed that C11 effectively suppressed FOXM1 transcriptional activity at concentrations of 10 µM in BT-549 cells and 20 µM in MDA-MB-231 cells. These findings underscore the potential of C11 as a potent FOXM1 inhibitor and highlight its promise for further development in TNBC therapy.