Shuganning injection, a traditional Chinese patent medicine, induces ferroptosis and suppresses tumor growth in triple-negative breast cancer cells

Abstract

Background: Triple-negative breast cancer (TNBC), lacking targeted therapies currently, is susceptible to ferroptosis, a recently defined form of cell death.

Purpose: To evaluate the anticancer activity of Shuganning injection (SGNI), a traditional Chinese patent medicine, on TNBC cells; To elucidate the mechanism of SGNI induced ferroptosis.

Methods: The anticancer activity of SGNI was examined via in vitro cell proliferation assays and in vivo xenograft growth assay. Ferroptosis was determined by flow-cytometric analysis of lipid ROS, labile iron pool measurement, and propidium iodide exclusion assay. The dependency on heme oxygenase 1 (HO-1) of SGNI induced ferroptosis was confirmed by genetic knockdown and pharmacological inhibition of the protein.

Results: SGNI selectively inhibited the proliferation of TNBC cells compared to non-TNBC breast cancer cells and normal cells. The cell death induced by SGNI in TNBC cells showed distinct morphology from apoptosis and could not be rescued by the pan-caspase inhibitor Z-VAD(OMe)-FMK. On the other hand, SGNI induced cell death was blocked by the lipid ROS scavengers ferrostatin-1 and liproxstatin-1, the acyl-CoA synthetase long chain family member 4 inhibitor rosiglitazone, and the iron chelators 1,10-phenanthroline and deferoxamine. These data indicated that SGNI induced a ferroptotic cell death of TNBC cells. Mechanistically, SGNI induced ferroptosis was dependent on HO-1, which promotes intracellular labile iron pool accumulation, and was alleviated by HO-1 knockdown and inhibition by tin protoporphyrin IX. In line with the in vitro data, SGNI significantly inhibited the xenograft growth of TNBC cell line MD-MB-231 in nude mice.

Conclusion: Collectively, our study elaborates on a promising regimen for TNBC treatment through induction of ferroptosis by SGNI, a traditional Chinese patent medicine currently available in the clinic, which merits further investigation.

Keywords: Ferroptosis; Shuganning injection; Triple-negative breast cancer.