Different inhibition of Nrf2 by two Keap1 isoforms α and β to shape malignant behaviour of human hepatocellular carcinoma

Chen, Feilong; Xiao, Mei; Feng, Jing; Wufuer, Reziyamu; Liu, Keli; Hu, Shaofan; Sun, Guan; Zhang, Yiguo

doi:10.1101/2022.07.15.500244

Cited by 3 publications

(1 citation statement)

References 42 publications

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“…Although we cannot rule out that aberrant NRF2 signalling may be partially responsible for the selective killing of ARID1A-KO cells following KEAP1 perturbation, our findings suggest that functions of KEAP1 outside of NRF2 regulation may underlie the genetic dependency we report herein. While KEAP1 has been extensively studied in the context of NRF2 regulation, it also has reported roles in the regulation of proteostasis, cytoskeleton formation and the cell cycle 58,59 . In fact, KEAP1 is an essential component of the KEAP1-CUL3-RBX1 ubiquitin ligase complex that targets various proteins for degradation, and also functions in autophagy with its interacting partner, p62 58,60,61 .…”

Section: Discussionmentioning

confidence: 99%

Genome-wide CRISPR screen identifies KEAP1 as a genetic dependency of ARID1A-deficient cells

Fournier,

Kalantari,

Wells

et al. 2023

Preprint

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ARID1A is the core DNA binding subunit of the BAF chromatin remodeling complex and is mutated in about ~8% of all cancers. The frequency of ARID1A loss varies between cancer subtypes, with clear cell ovarian carcinoma (CCOC) presenting the highest incidence at >50% of cases. Despite a growing understanding of the consequences of ARID1A-loss in cancer, there remains limited targeted therapeutic options for ARID1A-deficient cancers. Using a genome-wide CRISPR screening approach, we identify KEAP1 as a synthetic lethal partner of ARID1A in CCOC. Depletion or chemical inhibition of KEAP1 results in the selective killing of ARID1A-KO cells. While we confirm that KEAP1-NRF2 signalling is dysregulated in ARID1A-KO cells, we suggest that this synthetic lethality is not due to aberrant NRF2 signalling. Rather, we find that KEAP1 perturbation exacerbates genome instability phenotypes associated with ARID1A-deficiency. We also confirm the selective killing of ARID1A-KO cells by the KEAP1 inhibitor AI-1 in edited primary endometrial epithelial cells and organoids. Together, our findings uncover a novel therapeutic avenue for the treatment of cancers harboring ARID1A mutations.AUTHOR SUMMARYARID1A, a component of a protein complex that regulates DNA accessibility, is frequently mutated in various cancers. Ovarian clear cell carcinoma (CCOC) is particularly affected, with over 50% of cases showing ARID1A loss. Despite growing knowledge on ARID1A loss in cancer, therapeutic options for ARID1A-deficient tumors remain limited. Using high throughput CRISPR screening, we identified KEAP1 perturbation as a sensitivity of ARID1A-deficient cells in cell lines and patient-derived samples. While the exact mechanism underlying this sensitivity remains uncertain, we showed that perturbation of KEAP1 exacerbates the heightened DNA damage states associated with ARID1A-deficiency. Taking advantage of these findings, we showed that combination treatment against KEAP1 and the DNA repair protein ATR results in improved killing of ARID1A-depleted cancer cells. Ultimately, our results provide new knowledge on the consequences of ARID1A loss in cancer and suggest that KEAP1 inhibition may provide clinical benefit to selectively eliminate ARID1A-deficient tumours.

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Section: Discussionmentioning

confidence: 99%

Genome-wide CRISPR screen identifies KEAP1 as a genetic dependency of ARID1A-deficient cells

Fournier,

Kalantari,

Wells

et al. 2023

Preprint

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A novel crosstalk between Nrf2 and Smad2/3 bridged by two nuanced Keap1 isoforms

Chen

Xiao

Lou

et al. 2022

Preprint

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The Keap1-Nrf2 signalling to transcriptionally regulate antioxidant response element (ARE)-driven target genes has been accepted as key redox-sensitive pathway governing a vast variety of cellular stresses during healthy survival and disease development. Herein, we identified two nuanced isoforms α and β of Keap1, arising from its first and another in-frame translation starting codons, respectively. Those common and specific genes monitored by Keap1α and/or Keap1β were unravelled by transcriptomic sequencing of indicated experimental cell lines. Amongst them, an unusual interaction of Keap1 with Smad2/3 was discovered by parsing transcriptome sequencing, protein profiling, and immunoprecipitation data. Further examinations validated that Smad2/3 enable physical interaction with Keap1, as well as its isoforms α and β, by both EDGETSD and DLG motifs in the linker regions between their MH1 and MH2 domains, such that the stability of Smad2/3 and its transcriptional activity are enhanced with the prolonged half-lives and signalling responsiveness from the cytoplasmic to nuclear compartments. Such activation of Smad2/3 by Keap1, Keap1α or Keap1β was contributable to a competitively inhibitory effect of Nrf2. Overall, this discovery presents a novel functional bridge crossing the Keap1-Nrf2 and the TGF-β1-Smad2/3 signalling pathways in healthy growth and development.

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Age-Dependent Changes in Nrf2/Keap1 and Target Antioxidant Protein Expression Correlate to Lipoxidative Adducts, and Are Modulated by Dietary N-3 LCPUFA in the Hippocampus of Mice

Díaz,

Valdés-Baizabal,

de Pablo

et al. 2024

Antioxidants

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The brain has a high metabolism rate that may generate reactive oxygen and nitrogen species. Consequently, nerve cells require highly efficient antioxidant defenses in order to prevent a condition of deleterious oxidative stress. This is particularly relevant in the hippocampus, a highly complex cerebral area involved in processing superior cognitive functions. Most current evidence points to hippocampal oxidative damage as a causal effect for neurodegenerative disorders, especially Alzheimer’s disease. Nuclear factor erythroid-2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) is a master key for the transcriptional regulation of antioxidant and detoxifying systems. It is ubiquitously expressed in brain areas, mainly supporting glial cells. In the present study, we have analyzed the relationships between Nrf2 and Keap1 isoforms in hippocampal tissue in response to aging and dietary long-chain polyunsaturated fatty acids (LCPUFA) supplementation. The possible involvement of lipoxidative and nitrosative by-products in the dynamics of the Nrf2/Keap1 complex was examined though determination of protein adducts, namely malondialdehyde (MDA), 4-hydroxynonenal (HNE), and 3-nitro-tyrosine (NTyr) under basal conditions. The results were correlated to the expression of target proteins heme-oxygenase-1 (HO-1) and glutathione peroxidase 4 (GPx4), whose expressions are known to be regulated by Nrf2/Keap1 signaling activation. All variables in this study were obtained simultaneously from the same preparations, allowing multivariate approaches. The results demonstrate a complex modification of the protein expression patterns together with the formation of adducts in response to aging and diet supplementation. Both parameters exhibited a strong interaction. Noticeably, LCPUFA supplementation to aged animals restored the Nrf2/Keap1/target protein patterns to the status observed in young animals, therefore driving a “rejuvenation” of hippocampal antioxidant defense.

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Different inhibition of Nrf2 by two Keap1 isoforms α and β to shape malignant behaviour of human hepatocellular carcinoma

Cited by 3 publications

References 42 publications

Genome-wide CRISPR screen identifies KEAP1 as a genetic dependency of ARID1A-deficient cells

Genome-wide CRISPR screen identifies KEAP1 as a genetic dependency of ARID1A-deficient cells

A novel crosstalk between Nrf2 and Smad2/3 bridged by two nuanced Keap1 isoforms

Age-Dependent Changes in Nrf2/Keap1 and Target Antioxidant Protein Expression Correlate to Lipoxidative Adducts, and Are Modulated by Dietary N-3 LCPUFA in the Hippocampus of Mice

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