Journal Article

HIF-1α and HIF-2α Differently Regulate the Radiation Sensitivity of NSCLC Cells

Barbeau, Lydie M. O., van Gisbergen, Marike W., Yaromina, Ala, Olivo Pimentel, Veronica, Moreno Roig, Eloy, Dubois, Ludwig J., Hendrickx, Tessa C., Vooijs, Marc A., Groot, Arjan J., Giuranno, Lorena, Dams, Glenn, Ient, Jonathan

2019

Overview

The hypoxia-inducible transcription factors (HIF)-1/2α are the main oxygen sensors which regulate the adaptation to intratumoral hypoxia. The aim of this study was to assess the role of the HIF proteins in regulating the radiation response of a non-small cell lung cancer (NSCLC) in vitro model. To directly assess the unique and overlapping functions of HIF-1α and HIF-2α, we use CRISPR gene-editing to generate isogenic H1299 non-small cell lung carcinoma cells lacking HIF-1α, HIF-2α or both. We found that in HIF1 knockout cells, HIF-2α was strongly induced by hypoxia compared to wild type but the reverse was not seen in HIF2 knockout cells. Cells lacking HIF-1α were more radiation resistant than HIF2 knockout and wildtype cells upon hypoxia, which was associated with a reduced recruitment of γH2AX foci directly after irradiation and not due to differences in proliferation. Conversely, double-HIF1/2 knockout cells were most radiation sensitive and had increased γH2AX recruitment and cell cycle delay. Compensatory HIF-2α activity in HIF1 knockout cells is the main cause of this radioprotective effect. Under hypoxia, HIF1 knockout cells uniquely had a strong increase in lactate production and decrease in extracellular pH. Using genetically identical HIF-α isoform-deficient cells we identified a strong radiosensitizing of HIF1, but not of HIF2, which was associated with a reduced extracellular pH and reduced glycolysis.

• Publisher: MDPI AG,MDPI
• Subject: Adaptation / Basic Helix-Loop-Helix Transcription Factors - genetics / Basic Helix-Loop-Helix Transcription Factors - physiology / Cancer therapies / Carcinoma, Non-Small-Cell Lung - genetics / Carcinoma, Non-Small-Cell Lung - radiotherapy / Cell cycle / Cell Line, Tumor / Cell proliferation / CRISPR / Gene expression / Gene Knockout Techniques / Genotype & phenotype / Glycolysis / HIF / Humans / Hypoxia / Hypoxia-inducible factor 1 / Hypoxia-Inducible Factor 1, alpha Subunit - genetics / Hypoxia-Inducible Factor 1, alpha Subunit - physiology / Hypoxia-inducible factor 1a / Lactic acid / Lung carcinoma / Lung Neoplasms - genetics / Lung Neoplasms - radiotherapy / Medical prognosis / Metabolism / Non-small cell lung carcinoma / pH effects / Proteins / Radiation / Radiation Tolerance - genetics / radiotherapy / Small cell lung carcinoma / Transcription factors / Tumors