Bufalin Inhibits the PI3K/AKT Pathway by Targeting GTF3C4 to Impede Breast Cancer Progression.

Breast cancer incidence is rising globally, presenting challenges such as treatment side effects and drug resistance. Bufalin is a bufadienolides compound with potential anti-cancer effects. This study shows that bufalin inhibits malignant proliferation of MDA-MB-231 and MCF-7 cells and protects mice against breast cancer. Of note, GTF3C4 was identified as the target protein by Limited Proteolysis-Mass Spectrometry. GTF3C4 is overexpressed in breast cancer and associated with poor prognosis. RNA sequencing analysis reveals that the PI3K/AKT signaling pathway is a key contributor. Using cell thermal shift assays, drug affinity response target stability assays, and surface plasmon resonance, it was verified that bufalin can specifically bind to GTF3C4. Bufalin reduces GTF3C4 protein levels in vivo and in vitro, effectively inhibiting breast cancer progression by suppressing the PI3K/AKT signaling pathway. After the knockdown of GTF3C4, the PI3K/AKT signaling pathway is also suppressed, thereby inhibiting the proliferation of breast cancer cells and promoting apoptosis. Single-cell RNA sequencing results indicated that bufalin reduces the proportions of macrophages, neutrophils, and monocytes, and affects the strength of receptor-ligand signals between cells. Collectively, this study demonstrates that bufalin targets GTF3C4 to inhibit the PI3K/AKT pathway and remodels the tumor microenvironment, thereby hindering the malignant progression of breast cancer.