ABSTRACT
Objective: To investigate the effect of taraxerol on autophagy of breast cancer MCF-7 cells in vitro, and explore the related mechanisms. Method: The effect of various doses of taraxerol (12.5, 25, 50, 100, 200 μmol·L-1) on proliferation of MCF-7 cells was detected by methye thiazolye telrazlium (MTT) assay. The autophagy-inducing effect of taraxerol was observed by acridine orange staining, transmission electron microscope (TEM) and immunofluorescence. The expressions of autophagy-related proteins and the changes of mammalian target of rapamycin (mTOR) signaling pathway were determined by Western blot analysis. Result: The viability of MCF-7 cells was significantly inhibited by taraxerol. Acridine orange staining indicated that the acidic lysosomes increased significantly after treatment with taraxerol in MCF-7 cells. The autophagic structure in the treated group was observed by TEM. Immunofluorescence showed that the expression of microtubule-associated protein 1 light chain 3 (LC3) in the cells of the drug group was increased. Western blot demonstrated that the protein expressions of LC3-Ⅱ and Beclin-1 were increased in taraxerol-treated MCF-7 cells (PP-1 taraxerol group, combination group (taraxerol + 3-methyladenine, 3-MA) showed the down-regulation of LC3-Ⅱ in the MCF-7 cells (PPPConclusion: Taraxerol can induce autophagy in MCF-7 cells, which may be related to the inhibition of mTOR signaling pathway.