Hypoxia limits the tumor-suppressive effects of C/EBPd in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a horrid disease with a terrifyingly low 5- year survival rate of only 12%. While this rate has slightly increased over the past decade, the incidence of PDAC has risen faster, by about 1% every year. Pre-clinical models are being employed with the aim to better understand the underlying tumor biology but sadly, a translation into the clinic often fails due to unforeseen complications. In a previous study, we showed that the transcription factor C/EBPd has tumor-suppressive effects on PDAC cells in vitro. In this study, we take those findings a step further and assess the effect of C/EBPd in a preclinical PDAC model in mice. We establish that the lack of oxygen in vivo – hypoxia - counteracts the tumor-suppressive effects of C/EBPd in PDAC cells and suggest that this is partly mediated by a reciprocal feedback loop between C/EBPd and HIF-1a. Although RNA-sequencing shows that the tumor-suppressive effects of C/EBPd are not entirely abrogated under hypoxia, our study demonstrates the importance of considering major physiological parameters in order to make clinically relevant propositions. Overall design: MIA PaCa-2 cells were transduced with a doxycycline-inducible plasmid for CEBPD over-expression or with a control plasmid containing the doxycycline-inducible construct followed by a scrambled sequence. Cells were cultured under hypoxia (1% oxygen) and treated with 2 ug/ml doxycycline in triplicates for 48 hours prior to RNA extraction.