TY - JOUR
T1 - Imaging of HIF-1-active tumor hypoxia using a protein effectively delivered to and specifically stabilized in HIF-1-active tumor cells
AU - Kudo, Takashi
AU - Ueda, Masashi
AU - Kuge, Yuji
AU - Mukai, Takahiro
AU - Tanaka, Shotaro
AU - Masutani, Maki
AU - Kiyono, Yasushi
AU - Kizaka-Kondoh, Shinae
AU - Hiraoka, Masahiro
AU - Saji, Hideo
PY - 2009/6/1
Y1 - 2009/6/1
N2 - Hypoxia-inducible factor-1 (HIF-1) plays an important role in malignant tumor progression and in the development of resistance to radiotherapy. We designed a novel fusion protein (PTD-ODD-SAV [POS]) consisting of a protein transduction domain (PTD), streptavidin (SAV), and a portion of the oxygen-dependent degradation domain (ODD) of HIF-1α that confers the same oxygen-dependent regulation as HIF-1α on POS. (3- 123/125Iiodobenzoyl) norbiotinamide (123/125I-IBB) was conjugated to the SAV moiety of POS to synthesize 123/125I-IBB- labeled POS (123/125I-IPOS). The purpose of this study was to evaluate the feasibility of 123I-IPOS as an imaging probe for HIF-1-active tumor hypoxia. Methods: After a 24-h incubation of 125I-IPOS with various tumor cell lines under either normoxic (20% O2) or hypoxic (0.1% O2) conditions, the intracellular radioactivity was investigated. Then, the biodistribution of 123/125I-IPOS was examined with tumor-implanted mice, and an in vivo imaging study was performed. The tumoral accumulation of 125I-IPOS was compared with HIF-1 activity using the mice carrying tumors with the HIF-1-dependent luciferase reporter gene. Furthermore, the intratumoral localization of 125I-IPOS was examined by the autoradiographic study, and then the same slide was subjected to immunostaining for pimonidazole, which is the hypoxic marker. Results: The ratios of radioactivity in hypoxic cells to that in normoxic cells were more than 2. These results indicate incorporation of 125I-IPOS into these cells and degradation of 125I-IPOS by normoxic tumor cells. In the biodistribution study, 125I-IPOS accumulated in the tumor (1.4 ± 0.3 percentage injected dose per gram) 24 h after administration. At that time, 125I-IPOS showed high tumor-to-blood and tumor-to-muscle ratios (5.1 ± 0.3 and 14.0 ± 3.9, respectively). The tumors were clearly visualized by in vivo imaging 24 h after 123I-IPOS injection (tumor-to-muscle ratio was 9.6). The tumoral accumulation of 125I-IPOS correlated with HIF-1 activity (R = 0.71, P < 0.05), and its intratumoral distribution coincided with the hypoxic regions. Conclusion: 123I-IPOS is a potential probe for the imaging of HIF-1 activity in tumors. Given the role of HIF-1 in tumor biology, its detection may be considered an indicator of aggressive cancer phenotypes.
AB - Hypoxia-inducible factor-1 (HIF-1) plays an important role in malignant tumor progression and in the development of resistance to radiotherapy. We designed a novel fusion protein (PTD-ODD-SAV [POS]) consisting of a protein transduction domain (PTD), streptavidin (SAV), and a portion of the oxygen-dependent degradation domain (ODD) of HIF-1α that confers the same oxygen-dependent regulation as HIF-1α on POS. (3- 123/125Iiodobenzoyl) norbiotinamide (123/125I-IBB) was conjugated to the SAV moiety of POS to synthesize 123/125I-IBB- labeled POS (123/125I-IPOS). The purpose of this study was to evaluate the feasibility of 123I-IPOS as an imaging probe for HIF-1-active tumor hypoxia. Methods: After a 24-h incubation of 125I-IPOS with various tumor cell lines under either normoxic (20% O2) or hypoxic (0.1% O2) conditions, the intracellular radioactivity was investigated. Then, the biodistribution of 123/125I-IPOS was examined with tumor-implanted mice, and an in vivo imaging study was performed. The tumoral accumulation of 125I-IPOS was compared with HIF-1 activity using the mice carrying tumors with the HIF-1-dependent luciferase reporter gene. Furthermore, the intratumoral localization of 125I-IPOS was examined by the autoradiographic study, and then the same slide was subjected to immunostaining for pimonidazole, which is the hypoxic marker. Results: The ratios of radioactivity in hypoxic cells to that in normoxic cells were more than 2. These results indicate incorporation of 125I-IPOS into these cells and degradation of 125I-IPOS by normoxic tumor cells. In the biodistribution study, 125I-IPOS accumulated in the tumor (1.4 ± 0.3 percentage injected dose per gram) 24 h after administration. At that time, 125I-IPOS showed high tumor-to-blood and tumor-to-muscle ratios (5.1 ± 0.3 and 14.0 ± 3.9, respectively). The tumors were clearly visualized by in vivo imaging 24 h after 123I-IPOS injection (tumor-to-muscle ratio was 9.6). The tumoral accumulation of 125I-IPOS correlated with HIF-1 activity (R = 0.71, P < 0.05), and its intratumoral distribution coincided with the hypoxic regions. Conclusion: 123I-IPOS is a potential probe for the imaging of HIF-1 activity in tumors. Given the role of HIF-1 in tumor biology, its detection may be considered an indicator of aggressive cancer phenotypes.
KW - Hypoxia-inducible factor-1 (HIF-1)
KW - Molecular imaging
KW - Oncology
KW - Oxygen-dependent degradation (ODD)
KW - Protein transduction domain (PTD)
KW - Radiopharmaceuticals
KW - Tumor hypoxia
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U2 - 10.2967/jnumed.108.061119
DO - 10.2967/jnumed.108.061119
M3 - Article
C2 - 19443598
AN - SCOPUS:66649093239
SN - 0161-5505
VL - 50
SP - 942
EP - 949
JO - Journal of Nuclear Medicine
JF - Journal of Nuclear Medicine
IS - 6
ER -