Inhibition of Hypoxia-Inducible Factor-1α (HIF-1α) Protein Synthesis by DNA Damage Inducing Agents

• Published in: PloS one 2010-05, Vol.5 (5), p.e10522
• Main Authors: Lou, Jessica Jie Wei, Chua, Yee Liu, Chew, Eng Hui, Gao, Jie, Bushell, Martin, Hagen, Thilo
• Format: Article
• Language: English
• Subjects: Adenoviruses; Biochemistry; Biochemistry/Chemical Biology of the Cell; Biochemistry/Drug Discovery; Camptothecin; Cancer; Cyclin-dependent kinase; Damage prevention; Degradation; Deoxyribonucleic acid; DNA; DNA biosynthesis; DNA damage; DNA repair; Drug development; Drugs; Genes; Hypoxia; Hypoxia-inducible factors; Inhibition; Kinases; Medicine; Mitomycin; Mitomycin C; Molecular Biology/Translational Regulation; Mutation; Oxygen; p53 Protein; Pharmacy; Phosphorylation; Plasmids; Protein biosynthesis; Protein synthesis; Proteins; RNA polymerase; Rodents; Tissues; Transcription factors; Translation initiation; Tumorigenesis; Virology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0010522

Hypoxia-inducible factor (HIF) is a heterodimeric transcription factor that is composed of a hypoxia-inducible α subunit (HIF-1α and HIF-2α) and a constitutively expressed β subunit (HIF-1β). HIF mediates the adaptation of cells and tissues to low oxygen concentrations. It also plays an important role in tumorigenesis and constitutes an important therapeutic target in anti-tumor therapy. We have screened a number of reported HIF inhibitors for their effects on HIF-transcriptional activity and found that the DNA damage inducing agents camptothecin and mitomycin C produced the most robust effects. Camptothecin is a reported inhibitor of HIF-1α translation, while mitomycin C has been reported to induce p53-dependent HIF-1α degradation. In this study we demonstrate that the inhibitory effect of mitomycin C on HIF-1α protein expression is not dependent on p53 and protein degradation, but also involves HIF-1α translational regulation. Initiation of a DNA damage response with the small molecule p53 activator NSC-652287 (RITA) has been reported to inhibit HIF-1α protein synthesis by increasing the phosphorylation of eIF2α. However, we show here that even when eIF2α phosphorylation is prevented, the DNA damage inducing drugs mitomycin C, camptothecin and NSC-652287 still inhibit HIF-1α protein synthesis to the same extent. The inhibitory effects of camptothecin on HIF-1α expression but not that of mitomycin C and NSC-652287 were dependent on cyclin-dependent kinase activity. In conclusion, specific types of DNA damage can bring about selective inhibition of HIF-1α protein synthesis. Further characterization of the involved mechanisms may reveal important novel therapeutic targets.