Output of genome-scale shRNA screen in HKO1.

Quantitative parameters of whole-genome and reductase shRNA screens.

List of shRNAs on the custom reductase library.

Primers used for amplification and Illumina® sequencing of genomic DNA samples from shRNA screens.

Suppliers of cell lines and composition of cell culture media.

Primer sequences for evaluating shRNA-mediated knockdown of POR by quantitative real-time PCR.

Evaluation of SN30000-induced bystander cell killing in a co-culture system (S1); SN30000 clonogenic survival curves for HT-29, PANC-1 cells and HKO1 (S2); Plating efficiency in HT-29, PANC-1 and HKO2 reductase screens (S3); Density distributions and correlations of reductase screen sequencing data (S4); Log2 enrichment factors of shRNAs significantly selected in the reductase screens (S5); Depletion of POR protein by shRNAs in PANC-1 and HT-29 cells (S6); Replicate SN30000 clonogenic survival assays performed in stably transduced HT-29 and PANC-1 cells (S7); Measurement of plating efficiency in HKO1 and HKO2 whole-genome screens (S8); Coincidence of shRNAs significantly selected (Z > 1.96) in HT-29 and PANC-1 reductase screens and the HKO1 genome-wide screen (S9); Validation of POR shRNAs and clonogenic survival following SN30000 treatment of POR-knockout HCT116 cells (S10); Spatial distribution of POR and CA-IX expression in tongue SCC (S11); Quantitation of POR and CA-IX expression in HNSCC (S12); POR IHC staining in isogenic xenografts used for method development (S13); POR mRNA expression and sequence variation in the TCGA HNSCC dataset (S14).

Description of additional methods and procedures used in the study. Also includes Supplementary References.

Output of genome-scale shRNA screen in HKO2.

Spearman correlation of expression of flavoproteins with SN30000 metabolism in tumor cell lines.

Supplementary Figure Legends from Identification of P450 Oxidoreductase as a Major Determinant of Sensitivity to Hypoxia-Activated Prodrugs

Spearman correlation of expression of flavoproteins with TPZ metabolism in tumor cell lines.

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. Cancer Res; 75(19); 4211–23. ©2015 AACR.