The transcription factor NRF2 is a central regulator of cellular redox balance. Mutations in NRF2 and its negative
regulator KEAP1 are found in 15-34% of non-small cell lung cancer (NSCLC). The result of these mutations is
constitutive NRF2 activation and chronic induction of a battery of NRF2 target genes, which confers resistance
to chemo/radiation therapy. While targeting NRF2 holds great therapeutic potential, there is no effective strategy
to inhibit the consequences of pathogenic KEAP1/NRF2 signaling. It is therefore critical to identify and
understand vulnerabilities of KEAP1/NRF2 mutant NSCLC to develop effective therapies for patients harboring
these mutations. NRF2 controls the transcription of many antioxidant enzymes, thereby regulating the
detoxification of reactive oxygen species. However, it remains largely unknown which specific antioxidant
enzymes can be therapeutically targeted to reverse the profound resistance of NRF2/KEAP1 mutations to
oxidative stress, the key mediator of chemo/radiation therapy. Glutathione (GSH)/GSH reductase (GSR) and
thioredoxin (TXN)/thioredoxin reductase (TXNRD) are two parallel, compensating thiol-dependent antioxidant
pathways that critically regulate and maintain cellular thiol redox homeostasis and protein dithiol/disulfide
balance. My preliminary results indicate that both GSR and TXNRD1 are strongly induced by NRF2 activation
and contribute to the intrinsic resistance to the pro-oxidant therapies. However, they play unique roles in different
cellular compartments. Specifically, NRF2 induced GSR acts to protect mitochondria from oxidation, while
TXNRD1 protects the cytosol. Further, TXNRD1 upregulation is associated with the suppression of other
selenoproteins, suggesting that NRF2 activation causes an imbalance in selenium distribution. Given the key
role of selenoprotein in redox biology, the switch in the production of the different selenoproteins induced by
NRF2 activation may create novel vulnerabilities of NRF2 active NSCLC with therapeutic potential. This proposal
is designed to further strengthen these observations by defining the mechanistic basis of how GSR contributes
to NRF2-mediated resistance to oxidative stress, and to leverage the imbalanced selenoprotein translation to
develop potent therapeutic strategies for KEAP1/NRF2 mutant NSCLC. The following specific aims are pursued
in this application: Aim 1. Investigate the role of GSR in NRF2-mediated resistance to oxidative stress. Aim 2.
Define the role of NRF2 as a modulator of the selenoproteome in NSCLC. The knowledge and scientific expertise
that I acquire from these proposed studies will facilitate my transition to an independent position. My long-term
goal is to study the antioxidant enzymes in cancer, with a major focus on selenoproteins. In addition to the
scientific goal, I have outlined a detailed career development plan to obtain skillsets that are key for leading a
research laboratory and establishing a strong research program. I will conduct the proposed research and carry
out the training plan under the guidance of my mentoring committee. I will embark on the excellent academic
environment provided by Moffitt Cancer Center to achieve these goals and transition to an independent position.