Fig. 4

Overexpression of HIF-2α induces stem phenotype conversion and drug resistance by activating the Notch pathway. a Expression of Notch pathway-related proteins was detected in HIF-2α overexpressing MCF7 and MDA-MB-231 cells by western blot. b Expression of HIF-2α and Notch pathway-related proteins was detected after HIF-2α–overexpressing MCF7 cells were treated with L685,458 (2 μM) for 48 h by western blot. c Top: Cell viability was determined in HIF-2α–overexpressing MCF7 cells incubated with PTX and L685,458 (2 μM) for 48 h using the MTT assay. Bottom: Comparison of IC₅₀ values and resistance index. d Cell apoptosis was measured after HIF-2α overexpressing MCF7 cells were incubated with PTX (3 nM) and L685,458 (2 μM) for 48 h by flow cytometry. Quantification values are shown. e Self-renew ability was analyzed after stable HIF-2α–cDNA transfected MCF7 cells were incubated with PTX (3 nM) and L685,458 (2 μM) for 48 h. f Expression of c-Myc, OCT4 and Nanog proteins was detected after HIF-2α–overexpressing MCF7 cells were treated with L685,458 (2 μM) for 48 h. Data are the mean ± SD of three independent experiments performed in triplicate. ^*P < 0.05, ^**P < 0.01, ^***P < 0.0001 compared with the NC-cDNA group. ^#P < 0.05, ^###P < 0.0001 compared with the HIF-2α-cDNA group