Multi-Targeted Anti-Cancer Effects of Triptophenolide in Hormone-Responsive and Triple-Negative Breast Cancer Models

Breast cancer (BC) remains a significant therapeutic challenge, necessitating novel agents with multi-target efficacy. Here, we demonstrate that triptophenolide (TRI), a bioactive compound from Tripterygium wilfordii, exerts potent anti-BC activity across hormone-responsive (MCF-7) and triple-negative (MDA-MB-231) subtypes. In vitro, TRI inhibited proliferation in a concentration-dependent manner, with IC₅₀ values decreasing from 180.3 μg/mL (24 h) to 127.2 μg/mL (48 h) in MCF-7 cells, and from 322.5 μg/mL to 262.1 μg/mL in MDA-MB-231 cells. TRI treatment induced G1-phase arrest in both breast cancer subtypes, increasing the G1 population by 22.27% in MCF-7 cells and 10.64% in MDA-MB-231 cells. Concurrently, TRI triggered apoptosis, elevating apoptotic rates from 3.36% to 9.78% in MCF-7 cells and from 7.01% to 17.02% in MDA-MB-231 cells. These effects were associated with the significant upregulation of pro-apoptotic proteins BAX, BAK1, BIM, and cytochrome c (CYCS). Notably, TRI suppressed migration by 61.5% (MCF-7) and 71.5% (MDA-MB-231). In vivo, TRI treatment inhibited MCF-7 xenograft growth and reduced tumor volume (1207.5 vs. 285 mm³) and weight (0.22 vs. 0.1 g), while extending the survival time of tumor-bearing mice from 14-20 days to 24 days. These results position TRI as a promising lead therapeutic candidate against diverse BC subtypes, with mechanistic versatility surpassing single-target agents.