Research Article

The Synergistic Reducing Drug Resistance Effect of Cisplatin and Ursolic Acid on Osteosarcoma through a Multistep Mechanism Involving Ferritinophagy

Figure 6

Depletion of free iron reservoirs by DFO and inhibition of autophagy by 3-MA attenuated UA/Cis-induced ferroptosis. The apoptosis rate of HOS cells treated with UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA was measured by flow cytometry (a, b) (). The viability of HOS cells treated with Cis, UA, UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA was assessed by the CCK-8 assay (c) (). Mitochondrial morphology changes and autophagy in HOS cells were observed by TEM (d) (, scale bar: 2 μm, scale bar: 1 μm). MDA and 4-HNE levels in HOS cells treated with UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA (e, f) (). Representative immunofluorescence images of BODIPY were obtained after UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA treatment (g, k) (, scale bar: 100 μm). Intracellular Fe2+ levels were measured after treatment with UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA (h, l) (, scale bar: 25 μm). Measurement of TFR level by immunofluorescence staining of HOS cells after treatment with UA/Cis, UA/Cis/DFO, or UA/Cis/3-MA (i, m) (, scale bar: 50 μm). The expression of iron metabolism-related proteins in UA/Cis-, UA/Cis/DFO-, or UA/Cis/3-MA-treated HOS cells was determined by western blotting (j) (). The data are presented as the . vs. the UA/Cis group.
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