Journal: Molecular Biomedicine
Article Title: Nuclear prostaglandin E synthase 3 promotes hepatocellular carcinoma growth with immunosuppressive macrophage polarization via the SP1/TGF-β axis
doi: 10.1186/s43556-026-00431-6
Figure Lengend Snippet: Nuclear PTGES3 directly binds and transcriptionally activates SP1 . a Target identification. Venn diagram displaying the intersection between PTGES3-bound genes (identified by CUT&Tag) and known transcriptional regulators of TGFB1 (retrieved from the TRRUST v2 database). b Peak visualization. Representative Integrative Genomics Viewer (IGV) tracks showing specific PTGES3 enrichment at the SP1 promoter region. c Motif analysis. The specific G-rich motif sequence identified within the PTGES3 binding peak. d Direct binding verification (EMSA). Electrophoretic mobility shift assay with biotinylated SP1 promoter probes and purified PTGES3 protein. Lane 1: Free probe; Lane 2: Probe + Protein (Shift); Lane 3: Probe + Protein + 5 × WT Competitor (Competition); Lane 4: Probe + Protein + 5 × Mutant Competitor (No competition). e ChIP-qPCR. Chromatin immunoprecipitation validating PTGES3 recruitment to the SP1 promoter in Huh7 cells ( n = 3). Cells expressing negative control shRNA (shNC) or PTGES3 -targeting shRNA (sh PTGES3 ) were assayed using non-specific immunoglobulin G (IgG, black bars) or specific anti-PTGES3 antibodies (red bars). f Transcriptional activity. Dual-luciferase reporter assay in Huh7 cells ( n = 3). Cells were co-transfected with reporter plasmids containing either the Wild-Type (WT) or motif-mutated (Mut) SP1 promoter, alongside empty vector (Vector, white bars) or PTGES3 expression plasmids (red bars). Motif mutation completely abolishes PTGES3-mediated activation. g , mRNA regulation. qPCR analysis of SP1 mRNA levels in Huh7 cells ( n = 3). Comparisons are between shNC and sh PTGES3 groups. h Protein regulation. Western blot analysis and quantification of SP1 expression in Huh7 cells ( n = 3). Left panels: knockdown (shNC vs. sh PTGES3 ); Right panels: overexpression (Vector vs. PTGES3 ). i TGF-β secretion. ELISA quantification of TGF-β levels in the supernatant of Huh7 cells ( n = 4). Groups: siNC + Vector (control), si SP1 + Vector ( SP1 knockdown alone), siNC + PTGES3 ( PTGES3 overexpression), and si SP1 + PTGES3 (rescue). j Signaling rescue (si SP1 ). Western blot analysis of PI3K/AKT/mTOR pathway components in Huh7 cells. SP1 silencing (si SP1 + PTGES3 ) reverses pathway activation induced by PTGES3 alone (siNC + PTGES3 ). k Receptor dependency (ITD-1). Western blot analysis of the PI3K/AKT pathway in Huh7 cells treated with the selective TGF-β receptor inhibitor ITD-1 (5 μM). Groups: Vector vs. PTGES3 overexpression in the presence or absence of ITD-1. l HSP90 independence (17-AAG). Western blot analysis in Huh7 cells treated with the HSP90 inhibitor 17-AAG (0.5 μM). Statistical analysis. Data are presented as mean ± SEM. Individual values are superimposed on bars. Significance was determined using two-tailed unpaired Student's t -test (for g, h), Two-way ANOVA with Šídák's post hoc test (for e, f, i). ** P < 0.01, *** P < 0.001, **** P < 0.0001; ns, not significant. Abbreviations: CUT&Tag, Cleavage Under Targets and Tagmentation; IGV, Integrative Genomics Viewer; EMSA, electrophoretic mobility shift assay; ChIP, chromatin immunoprecipitation; qPCR, quantitative polymerase chain reaction; shRNA, short hairpin RNA; IgG, immunoglobulin G; siRNA, small interfering RNA; ELISA, enzyme-linked immunosorbent assay; WT, wild-type; Mut, mutant; PI3K, phosphoinositide 3-kinase; AKT, protein kinase B; mTOR, mechanistic target of rapamycin; TGF-β, transforming growth factor-beta; HSP90, heat shock protein 90; ANOVA, analysis of variance; SEM, standard error of the mean; NC, negative control
Article Snippet: Inhibitor Treatment: Pathway dependency was validated using Rapamycin (100 nM; Selleck Chemicals, Houston, TX, USA), ITD-1 (5 μM; Cat. No. S6713; Selleck Chemicals), or 17-AAG (0.5 μM; Cat. No. S1141; Selleck Chemicals).
Techniques: Drug discovery, Sequencing, Binding Assay, Electrophoretic Mobility Shift Assay, Purification, Mutagenesis, ChIP-qPCR, Chromatin Immunoprecipitation, Expressing, Negative Control, shRNA, Activity Assay, Luciferase, Reporter Assay, Transfection, Plasmid Preparation, Activation Assay, Western Blot, Knockdown, Over Expression, Enzyme-linked Immunosorbent Assay, Control, Two Tailed Test, Real-time Polymerase Chain Reaction, Small Interfering RNA