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RPRD1A stabilizes NRF2 and aggravates HCC progression through competing with p62 for TRIM21 binding.

ABSTRACT: NRF2 is the master transcriptional activator of cytoprotective genes and Kelch-like ECH-associated protein 1 (Keap1), a biosensor for electrophiles and oxidation, promotes NRF2 degradation in unstressed conditions. SQSTM1/p62, an oncogenic protein aberrantly accumulated in hepatocellular carcinoma (HCC), binds and sequestrates Keap1, leading to the prevention of NRF2 degradation. Here, we show that p15INK4b-related sequence/regulation of nuclear pre-mRNA domain-containing protein 1A (RPRD1A) is highly expressed in HCC tumors and correlated with aggressive clinicopathological features. RPRD1A competitively interacts with TRIM21, an E3 ubiquitin ligase of p62, resulting in the decrease of p62 ubiquitination and the increased sequestration for Keap1. Therefore, RPRD1A enhances the nuclear translocation of NRF2, which induces gene expression for counteracting oxidative stress, maintaining cancer cells survival, and promoting HCC development. Moreover, disturbing the redox homeostasis of cancer cells by genetic knockdown of RPRD1A sensitizes cancer cells to platinum-induced cell death. Our study reveals RPRD1A is involved in the oxidative stress defense program and highlights the therapeutic benefits of targeting pathways that support antioxidation.

SUBMITTER: Feng X

PROVIDER: S-EPMC8683478 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature

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RPRD1A stabilizes NRF2 and aggravates HCC progression through competing with p62 for TRIM21 binding.

Feng Xiaofan X Jiang Tianyi T Yang Chun C Pang Shujie S Ding Zhiwen Z Hu Heping H Wang Hui H Dong Liwei L Yang Ning N

Cell death & disease 20211217 1

NRF2 is the master transcriptional activator of cytoprotective genes and Kelch-like ECH-associated protein 1 (Keap1), a biosensor for electrophiles and oxidation, promotes NRF2 degradation in unstressed conditions. SQSTM1/p62, an oncogenic protein aberrantly accumulated in hepatocellular carcinoma (HCC), binds and sequestrates Keap1, leading to the prevention of NRF2 degradation. Here, we show that p15INK4b-related sequence/regulation of nuclear pre-mRNA domain-containing protein 1A (RPRD1A) is ...[more]

PMID: 34921137

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Project description:Nuclear factor erythroid 2-related factor 2 (Nrf2) dissociates from its inhibitor, Keap1, upon stress signals and subsequently induces an antioxidant response that critically controls the viral life cycle and pathogenesis. Besides intracellular Fc receptor function, tripartite motif 21 (TRIM21) E3 ligase plays an essential role in the p62-Keap1-Nrf2 axis pathway for redox homeostasis. Specifically, TRIM21-mediated p62 ubiquitination abrogates p62 oligomerization and sequestration activity and negatively regulates the Keap1-Nrf2-mediated antioxidant response. A number of viruses target the Nrf2-mediated antioxidant response to generate an optimal environment for their life cycle. Here we report that a nonstructural protein (NSs) of severe fever with thrombocytopenia syndrome virus (SFTSV) interacts with and inhibits TRIM21 to activate the Nrf2 antioxidant signal pathway. Mass spectrometry identified TRIM21 to be a binding protein for NSs. NSs bound to the carboxyl-terminal SPRY subdomain of TRIM21, enhancing p62 stability and oligomerization. This facilitated p62-mediated Keap1 sequestration and ultimately increased Nrf2-mediated transcriptional activation of antioxidant genes, including those for heme oxygenase 1, NAD(P)H quinone oxidoreductase 1, and CD36. Mutational analysis found that the NSs-A46 mutant, which no longer interacted with TRIM21, was unable to increase Nrf2-mediated transcriptional activation. Functionally, the NS wild type (WT), but not the NSs-A46 mutant, increased the surface expression of the CD36 scavenger receptor, resulting in an increase in phagocytosis and lipid uptake. A combination of reverse genetics and assays with Ifnar-/- mouse models revealed that while the SFTSV-A46 mutant replicated similarly to wild-type SFTSV (SFTSV-WT), it showed weaker pathogenic activity than SFTSV-WT. These data suggest that the activation of the p62-Keap1-Nrf2 antioxidant response induced by the NSs-TRIM21 interaction contributes to the development of an optimal environment for the SFTSV life cycle and efficient pathogenesis.IMPORTANCE Tick-borne diseases have become a growing threat to public health. SFTSV, listed by the World Health Organization as a prioritized pathogen, is an emerging phlebovirus, and fatality rates among those infected with this virus are high. Infected Haemaphysalis longicornis ticks are the major source of human SFTSV infection. In particular, the recent spread of this tick to over 12 states in the United States has increased the potential for outbreaks of this disease beyond Far East Asia. Due to the lack of therapies and vaccines against SFTSV infection, there is a pressing need to understand SFTSV pathogenesis. As the Nrf2-mediated antioxidant response affects viral life cycles, a number of viruses deregulate Nrf2 pathways. Here we demonstrate that the SFTSV NSs inhibits the TRIM21 function to upregulate the p62-Keap1-Nrf2 antioxidant pathway for efficient viral pathogenesis. This study not only demonstrates the critical role of SFTSV NSs in viral pathogenesis but also suggests potential future therapeutic approaches to treat SFTSV-infected patients.

Project description:Background and aimsDiabetes mellitus is a risk factor for hepatocellular carcinoma (HCC) in patients with nonalcoholic steatohepatitis (NASH). Dipeptidyl peptidase-4 inhibitor (DPP4i), an antidiabetic agent, is reported to affect cell proliferation. We aimed to investigate the effects of DPP4i on the progression of NASH-related HCC and its metabolic pathway in a mouse model.MethodsA mouse model of NASH-related HCC was used in this study. Eight-week-old mice were administered either DPP4i (sitagliptin 30 mg/kg/day; DPP4i group; n = 8) or distilled water (control group; n = 8) for 10 weeks. Then, HCC progression was evaluated by computed tomography. Changes in metabolites of HCC tissue were analyzed by metabolomic analysis. The localization and expression of p62, Keap1, Nrf2, and MCM7 were evaluated by immunostaining and immunoblotting, respectively.ResultsThe number and volume of HCC were significantly lower in the DPP4i group than in the control group (1.8 ± 1.2 vs. 4.5 ± 1.7/liver, p < 0.01; 11.2 ± 20.8 vs. 37.5 ± 72.5 mm3/tumor, p < 0.05). Metabolome analysis revealed that DPP4i significantly increased 6-phosphogluconic acid and ribose 5-phosphate levels and decreased the AMP-to-adenine and GMP-to-guanine ratios (AMP-to-adenine ratio 0.7 ± 0.2 vs. 2.0 ± 1.2, p < 0.01; GMP-to-guanine ratio 0.6 ± 0.3 vs. 1.5 ± 0.7, p < 0.01). Immunostaining showed that p62 was localized in the cytoplasm of HCC in the DPP4i group, while p62 was localized in the nucleus of HCC in the control group. Keap1, Nrf2, and MCM7 expression decreased significantly in the DPP4i group compared to that in the control group.ConclusionsWe demonstrated that DDP4i prevented the progression of NASH-related HCC in a mouse model. Furthermore, metabolome analysis revealed that DDP4i downregulated the pentose phosphate pathway with suppression of the p62/Keap1/Nrf2 pathway. Thus, DDP4i may prevent tumor progression through inhibition of metabolic reprogramming in NASH-related HCC.

Project description:Background & aimsDysregulation of one-carbon metabolism is considered an early hallmark of mitochondrial dysfunction and cancer metabolism. ALDH1L2 belongs to the aldehyde dehydrogenase family and plays an important role in tumor progression. However, little is known about the precise role and underlying mechanisms of ALDH1L2 in hepatocellular carcinoma (HCC).MethodsImmunohistochemistry, western blotting, and immunofluorescence staining were used to evaluate ALDH1L2 expression in HCC samples (n = 90) and cell lines (n = 9). A series of in vitro and in vivo assays were performed to explore the role and molecular mechanism of ALDH1L2 in HCC progression.ResultsALDH1L2 upregulation is associated with poor prognosis in HCC (hazard ratio 1.923; 95% confidence interval 1.03-3.59; p = 0.04). ALDH1L2 promotes tumor cell proliferation and metastasis by activating NRF2/IL-6/STAT3 signaling. ALDH1L2 promotes mitochondrial respiration, increases ATP production and protects HCC cells from reactive oxygen species-induced cellular damage via NRF2 stabilization. NRF2 also directly binds to the ALDH1L2 promoter and increases ALDH1L2 transcription, thereby establishing a positive feedback loop to maintain the function of ALDH1L2. The interaction between tumor-associated macrophages and ALDH1L2-overexpressing HCC cells further promotes HCC progression. In addition, ALDH1L2 knockdown enhances the anti-HCC activity of the tyrosine kinase inhibitor sorafenib.ConclusionsThese findings provide the first evidence indicating that ALDH1L2 is directly involved in tumor progression by interacting with tumor-associated macrophages through the Jak2/STAT3 signaling pathway and that ALDH1L2 may be a target molecule for HCC therapy.Impact and implicationsThis research highlights that ALDH1L2 could serve as a predictive and prognostic marker in HCC. We found that a positive feedback loop between ALDH1L2 and NRF2 promotes HCC progression by activating the IL-6/Jak2/STAT3 signaling axis and tumor-associated macrophage polarization. In addition, we found that ALDH1L2 knockdown enhances the anti-HCC effect of sorafenib.

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RPRD1A stabilizes NRF2 and aggravates HCC progression through competing with p62 for TRIM21 binding.

Publications

RPRD1A stabilizes NRF2 and aggravates HCC progression through competing with p62 for TRIM21 binding.

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