Abstract |
Hypoxia is a prevalent feature of many tumors contributing to disease progression and treatment resistance, and therefore constitutes an attractive therapeutic target. Several hypoxia-activated prodrugs (HAP) have been developed, including the phase III candidate TH-302 ( evofosfamide) and the preclinical agent SN30000, which is an optimized analogue of the well-studied HAP tirapazamine. Experience with this therapeutic class highlights an urgent need to identify biomarkers of HAP sensitivity, including enzymes responsible for prodrug activation during hypoxia. Using genome-scale shRNA screens and a high-representation library enriched for oxidoreductases, we identified the flavoprotein P450 ( cytochrome) oxidoreductase (POR) as the predominant determinant of sensitivity to SN30000 in three different genetic backgrounds. No other genes consistently modified SN30000 sensitivity, even within a POR-negative background. Knockdown or genetic knockout of POR reduced SN30000 reductive metabolism and clonogenic cell death and similarly reduced sensitivity to TH-302 under hypoxia. A retrospective evaluation of head and neck squamous cell carcinomas showed heterogeneous POR expression and suggested a possible relationship between human papillomavirus status and HAP sensitivity. Taken together, our study identifies POR as a potential predictive biomarker of HAP sensitivity that should be explored during the clinical development of SN30000, TH-302, and other hypoxia-directed agents.
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Authors | Francis W Hunter, Richard J Young, Zvi Shalev, Ravi N Vellanki, Jingli Wang, Yongchuan Gu, Naveen Joshi, Sreevalsan Sreebhavan, Ilan Weinreb, David P Goldstein, Jason Moffat, Troy Ketela, Kevin R Brown, Marianne Koritzinsky, Benjamin Solomon, Danny Rischin, William R Wilson, Bradly G Wouters |
Journal | Cancer research
(Cancer Res)
Vol. 75
Issue 19
Pg. 4211-23
(Oct 01 2015)
ISSN: 1538-7445 [Electronic] United States |
PMID | 26297733
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Copyright | ©2015 American Association for Cancer Research. |
Chemical References |
- Antineoplastic Agents
- Biomarkers
- CEN-209
- Cyclic N-Oxides
- Neoplasm Proteins
- Nitroimidazoles
- POR protein, human
- Phosphoramide Mustards
- Prodrugs
- RNA, Messenger
- RNA, Small Interfering
- TH 302
- Triazines
- Tirapazamine
- Cytochrome P-450 Enzyme System
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Topics |
- Activation, Metabolic
- Antineoplastic Agents
(pharmacokinetics, therapeutic use)
- Biomarkers
- Carcinoma, Squamous Cell
(enzymology, therapy, virology)
- Cell Hypoxia
(physiology)
- Cell Line, Tumor
- Chemoradiotherapy
- Cyclic N-Oxides
(pharmacokinetics)
- Cytochrome P-450 Enzyme System
(biosynthesis, genetics, physiology)
- Head and Neck Neoplasms
(enzymology, virology)
- High-Throughput Screening Assays
- Humans
- Neoplasm Proteins
(antagonists & inhibitors, biosynthesis, genetics, physiology)
- Nitroimidazoles
(pharmacokinetics)
- Papillomaviridae
(isolation & purification)
- Papillomavirus Infections
(virology)
- Phosphoramide Mustards
(pharmacokinetics)
- Prodrugs
(pharmacokinetics, therapeutic use)
- RNA Interference
- RNA, Messenger
(biosynthesis, genetics)
- RNA, Small Interfering
(pharmacology)
- Retrospective Studies
- Tirapazamine
- Triazines
(pharmacokinetics, therapeutic use)
- Tumor Microenvironment
- Tumor Stem Cell Assay
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