Browsing by Subject "KEAP1"

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    Inhibition of TXNRD or SOD1 overcomes NRF2-mediated resistance to β-lapachone
    (Elsevier, 2020-02) Torrente, Laura; Prieto-Farigua, Nicolas; Falzone, Aimee; Elkins, Cody M.; Boothman, David A.; Haura, Eric B.; DeNicola, Gina M.; Biochemistry and Molecular Biology, School of Medicine
    Alterations in the NRF2/KEAP1 pathway result in the constitutive activation of NRF2, leading to the aberrant induction of antioxidant and detoxification enzymes, including NQO1. The NQO1 bioactivatable agent β-lapachone can target cells with high NQO1 expression but relies in the generation of reactive oxygen species (ROS), which are actively scavenged in cells with NRF2/KEAP1 mutations. However, whether NRF2/KEAP1 mutations influence the response to β-lapachone treatment remains unknown. To address this question, we assessed the cytotoxicity of β-lapachone in a panel of NSCLC cell lines bearing either wild-type or mutant KEAP1. We found that, despite overexpression of NQO1, KEAP1 mutant cells were resistant to β-lapachone due to enhanced detoxification of ROS, which prevented DNA damage and cell death. To evaluate whether specific inhibition of the NRF2-regulated antioxidant enzymes could abrogate resistance to β-lapachone, we systematically inhibited the four major antioxidant cellular systems using genetic and/or pharmacologic approaches. We demonstrated that inhibition of the thioredoxin-dependent system or copper-zinc superoxide dismutase (SOD1) could abrogate NRF2-mediated resistance to β-lapachone, while depletion of catalase or glutathione was ineffective. Interestingly, inhibition of SOD1 selectively sensitized KEAP1 mutant cells to β-lapachone exposure. Our results suggest that NRF2/KEAP1 mutational status might serve as a predictive biomarker for response to NQO1-bioactivatable quinones in patients. Further, our results suggest SOD1 inhibition may have potential utility in combination with other ROS inducers in patients with KEAP1/NRF2 mutations.
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    KEAP1-Mutant Lung Cancers Weaken Anti-Tumor Immunity and Promote an M2-like Macrophage Phenotype
    (MDPI, 2024-03-20) Occhiuto, Christopher J.; Liby, Karen T.; Medicine, School of Medicine
    Considerable advances have been made in lung cancer therapies, but there is still an unmet clinical need to improve survival for lung cancer patients. Immunotherapies have improved survival, although only 20–30% of patients respond to these treatments. Interestingly, cancers with mutations in Kelch-like ECH-associated protein 1 (KEAP1), the negative regulator of the nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor, are resistant to immune checkpoint inhibition and correlate with decreased lymphoid cell infiltration. NRF2 is known for promoting an anti-inflammatory phenotype when activated in immune cells, but the study of NRF2 activation in cancer cells has not been adequately assessed. The objective of this study was to determine how lung cancer cells with constitutive NRF2 activity interact with the immune microenvironment to promote cancer progression. To assess, we generated CRISPR-edited mouse lung cancer cell lines by knocking out the KEAP1 or NFE2L2 genes and utilized a publicly available single-cell dataset through the Gene Expression Omnibus to investigate tumor/immune cell interactions. We show here that KEAP1-mutant cancers promote immunosuppression of the tumor microenvironment. Our data suggest KEAP1 deletion is sufficient to alter the secretion of cytokines, increase expression of immune checkpoint markers on cancer cells, and alter recruitment and differential polarization of immunosuppressive macrophages that ultimately lead to T-cell suppression.