Discovery of a Small-Molecule Inhibitor Targeting the ELF3-HSP27 Interaction to Suppress Breast Cancer Progression

Background: Breast cancer remains a leading cause of cancer-related mortality in women, largely due to metastasis and treatment resistance. ELF3, an ETS transcription factor, has been linked to cancer progression; however, the mechanisms regulating its activity remain incompletely understood. Methods: ELF3 expression and its association with patient survival were analyzed using GEO datasets and the Kaplan-Meier Plotter platform. Functional studies were performed using ELF3 knockdown in breast cancer cell lines, followed by WST-1 assays and crystal violet staining. Protein-protein interactions were evaluated using co-expression analysis, immunofluorescence, split luciferase complementation, GST pull-down, and yeast two-hybrid assays. Cycloheximide chase assays were conducted to assess ELF3 protein stability. A panel of small molecules was screened to identify inhibitors of the ELF3-HSP27 interaction, and a lead compound was further validated using biochemical and functional assays. Antitumor activity was evaluated in a xenograft mouse model. Results: High ELF3 expression was associated with poorer overall survival in breast cancer patients. HSP27 was identified as a binding partner that stabilizes ELF3 protein, thereby promoting breast cancer cell proliferation. A novel small-molecule inhibitor disrupting the ELF3-HSP27 interaction suppressed cancer cell growth in vitro and reduced tumor growth in vivo. Conclusions: The ELF3-HSP27 interaction represents a previously unrecognized contributor to breast cancer progression, and its disruption provides a promising therapeutic strategy.