Transcriptional differences in breast cancer cells exposed to acute versus chronic hypoxia.

Our previous studies demonstrated that exposing cells to acute hypoxic conditions in vitro (24 h at 1% oxygen) does not fully recapitulate exposure to intratumoral hypoxia (Godet et al., 2019). In this study, we sought to investigate whether chronic exposure to hypoxia in vitro (10 days at 1% oxygen) would better mimic the transcriptional effects of intratumoral hypoxia. To compare acute versus chronic hypoxic conditions, MDA-MB-231 cells were cultured for 1 or 10 days under 20% or 1% O2. To investigate the effect of reoxygenation, cells cultured for 10 days under 1% O2 were then subjected to 10 days under 20% O2. RNA was extracted using the Direct-zol miniRNA kit (Zymo) and samples with RIN>9 were submitted for library preparation, RNA sequencing and preliminary analysis.