SBIR-STTR Award

Enhanced metabolic and mitochondrial activity inherent in actively proliferating cancer cells generates an excessive amount of reactive oxygen species (ROS), associated with intracellular redox imbalance that impacts cellular viability.To survive chronic oxidative stress, cancer cells evolve to activate scavenging/anti-oxidant enzymes to restore redox balance. This differential activation of antioxidant pathways compared to normal cells provides a therapeutic window for novel cellular targets. Moreover, the effects of chemo- and radiotherapy (in part) are attributed to oxidative stress that causes irreversible oxidative damage and cell death, and activation of redox-regulating pathways is thought to promote resistance to such therapies. The obligatory dependence of cancer cells on antioxidant defense pathways as a fundamental pro-survival mechanism suggests the broad translational utility of their targeting in breast cancer. Modulation of redox-adaptation mechanisms represents a feasible strategy to eradicate cancer cells and/or restore chemosensitivity to conventional therapies. For the first time, we identified the heme (Fe2+-protoporphyrin IX) catabolic enzyme BLVRB (biliverdin IXß reductase) as a new cellular target in breast cancer. We demonstrated the requisite and non-redundant pro- survival antioxidant function of BLVRB in breast cancer cells, coupled with therapy resistance and poor outcomes in breast cancer patients. The primary hypothesis of this application is that BLVRB functions in a redox- regulated pathway of antioxidant handling and cytoprotection in breast cancer cells. The secondary hypothesis is that BLVRB-selective inhibitor(s) may be developed as a novel and potentially non-toxic strategy for breast cancer treatment with minimal predicted off-target effects in normal cells. Using (1) BLVRB/inhibitor co-crystal structures, (2) computational RMSD matrices for SARs, and (3) extensive ADME/T and PK studies, we identified two lead compounds with excellent bioavailability and oral PK characteristics that selectively block BLVRB redox coupling. The objectives of this proposal are (1) to extend initial proof-of-principle studies for BLVRB pre-clinical target validation using in vivo breast cancer models, and (2) to characterize first-in-class BLVRB-selective inhibitors for in vitro and in vivo efficacy. Study Design: We will apply in vivo genetic models for target validation, simultaneously addressing redox-dependent mechanisms by gene complementation studies using BLVRB+/+ and BLVRB-/- breast cancer isogenic lines: (1) to confirm requisite functions in tumor growth and metastatic burden; (2) to establish redox-dependent phenotype (Aim 1). Aim 2 will validate the pre-clinical efficacy of lead compounds using well-established phenotypic read-outs in vitro and in orthotopic breast cancer implantation models. We will also address synthetic lethality BLVRB inhibitors with standard-of-care chemotherapy in vivo. Impact: If successful, the proposed work would be first-in-class pre-clinical validation of redox inhibitors in breast cancer, representing a potential paradigm shift for cancer therapeutics.

Public Health Relevance Statement:
The goals of this proposal are 1) to validate in mouse models BLVRB (biliverdin IXß reductase) as a new cellular target in breast cancer, and 2) to develop new BLVRB inhibitors as a novel breast cancer therapy with the predicted minimal toxicity to normal cells. If successful, our study would be pre-clinical validation of first-in-class BLVRB redox inhibitors in breast cancer, representing a potential paradigm shift for cancer therapeutics.

Project Terms:
Acceleration; Animals; inhibitor; Antioxidants; anti-oxidant; Biliverdine; Biliverdin; Dehydrobilirubin; Ooecyan; Uteroverdine; Biochemistry; Biological Chemistry; Biological Assay; Assay; Bioassay; Biologic Assays; Biological Availability; Bioavailability; Physiologic Availability; Blood Cells; Peripheral Blood Cell; malignant breast neoplasm; Breast Cancer; malignant breast tumor; Malignant Neoplasms; Cancers; Malignant Tumor; malignancy; neoplasm/cancer; Cell Death; necrocytosis; Cell Survival; Cell Viability; Pharmaceutical Chemistry; Medicinal Chemistry; Pharmaceutic Chemistry; Enzymes; Enzyme Gene; Equilibrium; balance; balance function; Feasibility Studies; Goals; Heme; Ferroprotoporphyrin; Protoheme; ferroheme; Human; Modern Man; Human Genetics; In Vitro; Laboratories; Lead; Pb element; heavy metal Pb; heavy metal lead; Lipid Peroxidation; Mitochondria; mitochondrial; Genetic Models; Mus; Mice; Mice Mammals; Murine; Names; name; named; naming; Oxidation-Reduction; Redox; oxidation reduction reaction; Oxidoreductase; Dehydrogenases; Oxidoreductase Gene; Reductases; Phenotype; Radiation therapy; Radiotherapeutics; Radiotherapy; radiation treatment; treatment with radiation; Reagent; Research Design; Study Type; study design; Research Support; Technology; Time; Tissues; Body Tissues; Work; protoporphyrin IX; Generations; Active Oxygen; Oxygen Radicals; Pro-Oxidants; Reactive Oxygen Species; gene complementation; Chronic; Phase; Biochemical; Oxidative Stress; Intellectual Property; Therapeutic; Metabolic; Genetic; cancer cell; Malignant Cell; Dependence; Oral; Cytoprotection; Cell Protection; cytoprotective; Ablation; tumor growth; cellular targeting; Toxic effect; Toxicities; Structure; novel; Modeling; Intervention; Intervention Strategies; interventional strategy; Normal Cell; Address; Breast Cancer Model; Breast tumor model; mammary cancer model; mammary tumor model; Breast Cancer Treatment; Data; Breast Cancer Cell; breast tumor cell; Inhibition of Cancer Cell Growth; Pre-Clinical Model; Preclinical Models; Proliferating; Reproducibility; in vitro Assay; in vivo; in vivo Model; Cancer Biology; Translational Research; Translational Science; translation research; translational investigation; Validation; validations; Characteristics; Development; developmental; Pathway interactions; pathway; pre-clinical; preclinical; intervention efficacy; therapeutic efficacy; therapy efficacy; Treatment Efficacy; Outcome; Coupled; Coupling; innovate; innovative; innovation; resistant; Resistance; anticancer therapeutic; anti-cancer therapeutic; Cellular model; Cell model; clinical relevance; clinically relevant; implantation; chemotherapy; murine model; mouse model; commercialization; standard of care; conventional treatment; conventional therapy; oxidative injury; oxidative damage; pre-clinical efficacy; preclinical efficacy; anti-oxidant enzyme; antioxidant enzyme; Genetic study; Breast Tumor Patient; Breast Cancer Patient; Breast Cancer therapy; pre-clinical development; preclinical development; model of human; human model; orthotopic breast adenocarcinoma; orthotopic breast carcinoma; orthotopic breast tumor; orthotopic breast cancer; Infrastructure; chemoresistant; chemotherapy resistance; chemotherapy resistant; Chemoresistance; pharmacologic