Inhibition of autophagic flux by the curcumin analog EF-24 and its antiproliferative effect on MCF-7 cancer cells.

Abstract

5-Bis[(2-fluorophenyl)methylene]-4-piperidinone (EF-24) is a curcumin analog, which was identified for its physiochemical stability and diverse pharmacological functions. In the present study, EF-24 was added to the breast cancer cell line MCF-7 and its cellular effects were characterized. The results indicated that EF-24 possessed antiproliferative and antimigratory activities on MCF-7 cells as determined by MTT assay, wound healing, and transwell assay, respectively. In addition, the autophagosomal vesicles could be detected by acridine orange staining and electron microscope analysis in EF-24-treated cells. Conversion of LC3-I to LC3-II was also investigated following EF-24 treatment of the cells. However, the expression analysis of p62 and LC3 revealed that EF-24 could inhibit autophagic flux in MCF-7 cells. Confocal microscopy suggested that EF-24 could inhibit the degradation of autophagic vesicles by blocking the fusion of autophagosomes with lysosomes. EF-24 could also induce apoptosis of MCF-7 cells as determined by Hoechst 33342 staining, flow cytometry analysis, and western blot analysis. Moreover, treatment of the cells with the autophagy inhibitor 3-MA enhanced the PARP1 cleavage of EF-24-treated MCF-7 cells, which indicated the crosstalk between autophagy and apoptosis in breast cancer cells. Additional investigation of EF-24 should be performed in future studies to assess its antiproliferation and antimigratory effects on MCF-7 cells. However, the current results provide a solid foundation for the potential in vivo anticancer activity of this compound.