Imatinib Impedes EMT and Notch Signalling by Inhibiting p300 Acetyltransferase in Breast Cancer Cells

Breast cancer remains a leading cause of cancer-related mortality among women, with current therapeutic approaches often limited by resistance and recurrence, especially in aggressive subtypes like triple-negative breast cancer. Drug repurposing has emerged as a promising strategy to address these challenges. In this study, we investigate the potential of Imatinib, a repurposed tyrosine kinase inhibitor, to inhibit epithelial-mesenchymal transition (EMT) in breast cancer cells by modulating the Notch signalling pathway. Our findings reveal that Imatinib treatment leads to a significant reduction in cancer cell stemness, invasiveness, and migration potential, alongside decreased colony-forming ability. EMT reversal was marked by a 2.71-fold increase in E-cadherin expression, with concurrent downregulation of mesenchymal markers, including Fibronectin (1.78-fold) and Slug (2.15-fold). Mechanistically, Imatinib was found to inhibit p300 acetyltransferase activity, resulting in reduced levels of H3K18Ac and H3K27Ac, which in turn led to the downregulation of key Notch pathway proteins such as HES1 (2.94-fold), AKT (2.08-fold), and p21 (1.88-fold). These results highlight the ability of Imatinib to suppress EMT through modulation of the Notch signalling pathway, offering a novel therapeutic avenue for breast cancer treatment. Overall, Imatinib demonstrates considerable potential for repurposing in breast cancer management by targeting critical oncogenic pathways involved in EMT and cancer progression.