Journal: Journal of Experimental & Clinical Cancer Research : CR
Article Title: Targeting NOTCH1-KEAP1 axis retards chronic liver injury and liver cancer progression via regulating stabilization of NRF2
doi: 10.1186/s13046-025-03488-3
Figure Lengend Snippet: NOTCH1 interacts with and recruits KEAP1 in hepatocytes, leading to NRF2 polyubiquitination degradation under CCl 4 challenge. ( A ) THLE2 cells after transfection with Flag-NOTCH1 or the empty Vector were incubated with CCl 4 for 24 h simultaneously in the presence of the protein synthesis inhibitor cycloheximide (CHX; 50 µg/ml) for the indicated times (0 h, 3 h, 6 h, 9 h). Relative protein expression levels for NRF2 in transfected THLE2 cells after time-course treatment were quantified ( n = 4 per group). ( B ) Immunoblotting detection of Flag-NOTCH1 transfected THLE2 cells with/without CCl 4 (24 h), MG132 (20 µM, 12 h) and CHO (20 µM, 12 h) treatment ( n = 4 per group). ( C ) Left, the human THLE2 cells were transfected with the indicated plasmids. Anti-Nrf2 immunoprecipitates were analyzed by immunoblotting with anti-Ub antibody for the examination of ubiquitin-conjugated Nrf2. Right, the human THLE2 cells were transfected with the indicated plasmids. Anti-K48-Ub immunoprecipitates were analyzed by immunoblotting with anti-Ub antibody for the examination of ubiquitin-conjugated Nrf2. ( D ) The human THLE2 cells transfected with Ad NOTCH1 or AdGFP were incubated with CCl 4 for 24 h, and were then collected for qPCR analysis of NOTCH1 and KEAP1 ( n = 5 per group). ( E ) Western blot analysis for NOTCH1 and KEAP1 protein expression levels in 24 h of CCl 4 -treated THLE2 cells with or without Ad NOTCH1 transfection ( n = 4 per group). ( F ) Immunoprecipitation and western blot analysis indicating the binding of KEAP1 to NOTCH1 in human THLE2 cells transfected with Flag-NOTCH1 and HA-tagged KEAP1 (HA-KEAP1) under CCl 4 exposure. ( G ) Immunoprecipitation and immunoblotting assay showing the binding of KEAP1 to NOTCH1 in the liver samples of CCl 4 -treated mice; the IgG was served as a control. ( H ) Representative immunoblotting bands for GST precipitation showing NOTCH1-KEAP1 direct binding by treating purified NOTCH1-His with purified KEAP1-HA-GST or by treating KEAP1-His with purified NOTCH1-HA-GST in THLE2 cells. ( I ) Representative IF images showing NOTCH1 (green) and KEAP1 (red) in THLE2 cells challenged with/without CCl 4 for 24 h ( n = 5 independent biological replicates with 8 images per group). ( J ) Molecular docking analysis between NOTCH1 and KEAP1 protein. ( K ) Representative western blot of KEAP1 and NRF2 in THLE2 cells transfected with varying amounts of Flag-NOTCH1 with or without CCl 4 incubation for 24 h. ( L ) Luciferase assay of the fluorescence intensity of THLE2 cells transfected with increasing counts of Flag-NOTCH1 plasmids in response to HG treatment for 24 h ( n = 6 per group). ( M ) Western blot results for KEAP1 and NRF2 in the isolated hepatocytes from the shown groups ( n = 4 per group). ( N ) Schematic indicating full-length and truncated NOTCH1 (upper, left) and KEAP1 (upper, right) with representative Co-IP results (bottom) for the mapping analysis of the domains responsible for the NOTCH1-KEAP1 interaction in human THLE2 cells. ( O ) Western blots of NICD1, KEAP1, NRF2, GPX4, and p-NF-κB in human THLE2 cells transfected with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant at 24 h after CCl 4 treatment ( n = 3 per group). ( P ) DCF-DA staining, DHE staining, and Mito-SOX staining, and ( Q ) quantification for ROS production by respective staining were performed in human THLE2 cells transfected with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant in response to CCl 4 treatment for 24 h. ( R ) Lipid peroxidation was examined by C11-BODIPY in human THLE2 cells with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant under CCl 4 treatment for 24 h; red fluorescence represents the reduction form, while green fluorescence represents the oxidized form. ( S ) Mean intensity for the ratio of the oxidized form to reduced form was quantified related to C11-BODIPY staining ( n = 5 per group). ( T ) Mito-Tracker was used to examine the mitochondrial structure changes of THLE2 cells transfected with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant under CCl 4 treatment for 24 h, and the mean mitochondrial size was then quantified ( n = 6 per group). ( U ) Measurements for MDA levels, GSH contents, GSH/GSSG ratio, Fe 2+ levels and ATP levels in 24 h of CCl 4 -treated THLE2 cells with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant transfection ( n = 6 per group). ( V ) qPCR analysis for the mRNA expression levels of genes involved in oxidative stress and ferroptosis as shown in THLE2 cells transfected with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant after CCl 4 incubation for 24 h ( n = 4 in each group). ( W ) The mRNA expression levels of inflammatory genes were evaluated by qPCR in 24 h CCl 4 -incubated THLE2 cells transfected with AdGFP, Ad NOTCH1 (WT) or the ∆ANK NOTCH1/NICD1 variant ( n = 4 in each group). Data are presented as mean ± SEM. P < 0.05 indicates statistical significance. Two-tailed unpaired t -test was used to determine the p -values in ( A ), ( E ) and ( F ); Statistical comparisons in ( L ), ( M ), ( O ), ( Q ), ( S ) to ( W ) were performed using one-way ANOVA with a Tukey post-hoc analysis; the results in ( C ), ( G ) to ( I ), ( K ), and ( N ) were obtained from three independent experiments
Article Snippet: Human THLE2 cell line (#CRL-2706), human HCC-related cell lines MHCC97H, SNU-182, SNU-398 and Hep3B were purchased from the American Type Culture Collection (ATCC).
Techniques: Transfection, Plasmid Preparation, Incubation, Expressing, Western Blot, Ubiquitin Proteomics, Immunoprecipitation, Binding Assay, Control, Purification, Luciferase, Fluorescence, Isolation, Co-Immunoprecipitation Assay, Variant Assay, Staining, Two Tailed Test