A new study published in Current Molecular Pharmacology reveals that gramine, a natural indole alkaloid, effectively suppresses triple-negative breast cancer by triggering ferroptosis, an iron-dependent form of programmed cell death. Researchers screened 27 indole alkaloids and identified gramine as a potent and selective inhibitor of TNBC cell growth, with IC₅₀ values around 22–28 μM and minimal toxicity to normal breast epithelial cells.
Mechanistically, gramine directly binds to the E3 ubiquitin ligase CUL3, reducing its activity toward the oncoprotein MTDH. This leads to MTDH stabilization, which in turn downregulates ferroptosis inhibitors such as GPX4 and SLC3A2, while increasing intracellular ROS, iron, and MDA levels. "We uncovered a novel regulatory pathway where gramine targets the CUL3–MTDH axis to drive ferroptosis," said Yuanliang Yan, corresponding author of the study. In both 4T1 and MDA-MB-231 mouse models, gramine significantly inhibited tumor growth without causing systemic toxicity.
These findings position gramine as a promising lead compound for TNBC therapy and open new avenues for targeting ferroptosis in drug-resistant cancers.
