Fig. 1.

Intermittent hypoxia induces chemo- and immuno-resistance in non-small cell lung cancer cells. a Experimental settings. Cells were cultured in the following conditions: normoxia (at 20% O₂ for 24 h, N), hypoxia (at 1% O₂ for 24 h, H), hypoxia/normoxia (12 h at 1% O₂ followed by 12 h at 20% O₂, H/N), hypoxia/normoxia/hypoxia or intermittent hypoxia (12 h at 1% O₂ followed by 12 h at 20% O₂ and 12 h at 1% O₂, H/N/H). b 28 non-small cell lung cancer cell lines were incubated as reported in a, then subjected to a 48 h treatment in normoxia (20% O₂) with increasing concentrations (from 1 × 10^− 9 to 1 × 10^− 5 M) of cisplatin (Pt) and docetaxel (Dx). Cell viability was measured by a chemiluminescence-based assay, in technical quadruplicates (n = 3 biological replicates). The IC₅₀ was calculated with the GraphPad Prism 9 software and is represented in a colorimetric scale. c 28 non-small cell lung cancer cell lines were incubated as reported in a, then subjected to flow cytometry analysis to evaluate the levels of ABCB1, ABCC1 and ABCA1, in technical duplicates (n = 3 biological replicates). The percentage of positive cells is represented in a colorimetric scale. d Representative histograms of ABCB1, ABCC1 and ABCA1 levels, measured by flow cytometry, in NCI-H2228 cells