Fig. 1

Chronic hypoxia increases breast cancer cell resistance to PTX and HIF-2α expression. a mRNA levels of HIF-1α and HIF-2α in MCF7 cells under normoxia or hypoxia for 6–48 h were detected by qRT-PCR. b mRNA levels of HIF-1α and HIF-2α in MCF7 cells under normoxia or hypoxia for 16–48 h were analyzed from GSE47533. c mRNA levels of HIF-1α and HIF-2α in MCF7 and MCF7 MS cells. d mRNA levels of HIF-1α and HIF-2α in MCF7 and MCF7 MS cells from GSE58383. e Protein levels of HIF-1α and HIF-2α in MCF7 and MCF7 MS cells. Statistical significance of detected protein expression is also shown. f Left panel: Cell viability of MCF7 cells treated with PTX (0–300 nM) under normoxia (20% O₂) or hypoxia (1% O₂) for 48 h was detected by MTT assay. Right panel: Comparison of IC₅₀ values of MCF7 and MCF7 MS cells treated with different concentrations of PTX for 48 h. Data are the mean ± SD from three independent experiments. ^*P < 0.05, ^**P < 0.01, ^***P < 0.0001 compared with the normoxia group