The combination of hypoxia-response enhancers and an oxygen-dependent proteolytic motif enables real-time imaging of absolute HIF-1 activity in tumor xenografts.
The transcriptional activity of hypoxia-inducible factor-1 (HIF-1) is associated with tumor malignancies; therefore, it is important to comprehend its dynamism in solid tumors. However, a molecular imaging strategy to accurately access it remains to be developed. We constructed here a novel HIF-1-dependent reporter gene, 5HREp-ODD-luc, in which 5 copies of the hypoxia-response element (5HRE) enhance expression of the oxygen-dependent degradation (ODD) domain and luciferase (luc) fusion under hypoxia. Because the ODD domain caused the oxygen-dependent degradation of the ODD-Luc protein, the novel reporter gene showed little leak of luminescence under normoxia. Such a property caused an increase of the hypoxia-responsiveness up to about 4.7 x 10(4) -fold. Moreover, the ODD domain caused rapid degradation of the ODD-Luc protein under normoxia, the luminescence reflected the dynamism of HIF-1 activity in real-time. The superiority of the novel reporter gene will surely accelerate analysis of the intratumoral HIF-1 activity during tumor progression and cancer treatments.
Harada
Hiroshi
H
Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. hharada@kuhp.kyoto-u.ac.jp
Kizaka-Kondoh
Shinae
S
Itasaka
Satoshi
S
Shibuya
Keiko
K
Morinibu
Akiyo
A
Shinomiya
Kazumi
K
Hiraoka
Masahiro
M
D001483:Base Sequence; D015687:Cell Hypoxia / Q000187:drug effects*; D017931:DNA Primers; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D014183:Transplantation, Heterologous
D017931:DNA Primers; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010100:Oxygen