Journal: Theranostics
Article Title: Crosstalk between macrophage-derived PGE 2 and tumor UHRF1 drives hepatocellular carcinoma progression
doi: 10.7150/thno.69494
Figure Lengend Snippet: TAMs promote HCC progression via the UHRF1 and CSF1 network. (A) Left: Immunofluorescent staining of CD68 + TAMs (red) in xenograft H22 tumors expressing nonsense control shRNA (shNC) or shUhrf1. The nuclei (blue) were stained by DAPI. Scale bar, 50 µm. Right: CD68 positive cells per field. Six randomly selected microscopic fields per sample. n = 6 samples per group, *P = 0.0007. Student's t -test. (B, C) PGE 2 secretion (B) and COX-2 expression (C) in human HCC TAMs. TAMs were incubated with the supernatants of HepG2 cells expressing control vector (HepG2 Ctrl sup.) or UHRF1 (HepG2 UHRF1 sup.) for 24 hours. n = 3, *P = 0.0031. Student's t -test. (D, E) The relevant mRNA levels in HepG2 cells stably expressing nonsense control shRNA (shNC) and shUHRF1 (D) , or expressing empty vector (Vector) and UHRF1 (E) . n = 3, *P < 0.05, versus corresponding control (shNC or Vector). Student's t -test. (F) CSF1 and CCL14 protein levels in HepG2 cells stably expressing empty vector (Vector) or UHRF1. (G) COX-2 protein levels in TAMs incubated with the supernatants from HepG2 cells or UHRF1-overexpressing HepG2 cells. HepG2 cells were treated without or with CSF1 neutralizing antibody (anti-CSF1, 2 μg/mL) for 24 hours. (H) PGE 2 secretion from human HCC TAMs. TAMs were incubated with the supernatants from HepG2 cells or UHRF1-overexpressing HepG2 cells that were treated without or with anti-CSF1 (2 µg/mL) for 48 hours. Isotype IgG as an antibody control. n = 3, *P = 0.03117. Student's t -test. (I) COX-2 protein levels in human HCC TAMs incubated with the supernatants from HepG2 cells or UHRF1-overexpressing HepG2 cells that were treated without or with siRNA against CSF1 (siCSF1) for 48 hours. (J) Left: Schematics showing transwell assays analyzing human HCC TAMs. Human TAMs were seeded in the upper chamber. HepG2 cells (HepG2 Ctrl ) or UHRF1-overexpressing HepG2 cells (HepG2 UHRF1 ) were seeded in the lower chamber. TAMs were cultured in the medium without or with anti-CSF1 (2 μg/mL). Isotype IgG as an antibody control. Right: Percentages of migrated TAMs relative to total TAMs. n = 3 with replicates. *P = 1.39 × 10 -4 , versus Control (HepG2 Ctrl in medium without anti-CSF1). One-way ANOVA with Dunnett's multiple comparisons test. (K) DNA methylation of CpG islands in the CSF1 promoter in HepG2 cells stably expressing control vector (Vector), UHRF1, shNC or shUHRF1. Closed circles indicate methylated CpGs. Open circles represent unmethylated CpGs. Percentage of DNA methylation (methylated CpGs/ total CpGs) is given at the bottom of each panel. (L) Pearson correlation between UHRF1 mRNA levels and CSF1 promoter methylation levels in human HCC tissues. 16 HCC patients. (M) ChIP assay showing DNMT1 abundance on the CSF1 promoter in HepG2 cells stably expressing shNC or shUHRF1. (N) CSF1 protein levels in HepG2 cells and shUHRF1-expressing HepG2 cells that were transfected without or with siRNA against DNMT1 (siDNMT1). (O, P) Tumor growth (O) and overall survival (P) of the mice. Mice were subcutaneously inoculated with H22 cells stably expressing shUhrf1 (H22 shUhrf1 ) or shNC (H22 shNC ). Half of the mice in each group were intraperitoneally injected with Clodronate liposomes to deplete macrophages (H22 shUhrf1 + MΦ-dep., and H22 shNC + MΦ-dep.). n = 4 per group. In O , *P = 0.0006, H22 shNC + MΦ-dep. versus H22 shNC ; P = 0.0740 (N.S.), H22 shUhrf1 + MΦ-dep. versus H22 shUhrf1 ; Student's t -test. In P , *P = 0.0169, H22 shNC + MΦ-dep. versus H22 shNC ; P = 0.1753, H22 shUhrf1 + MΦ-dep. versus H22 shUhrf1 ; Log-rank (Mantel-Cox) test. (Q) Effect of celecoxib on tumor growth. H22 cells were inoculated into the left posterior flank of the Balb/c mice. The tumor bearing mice were then treated with daily oral administration of celecoxib (CXB, 150 mg/kg, n = 6) or solvent (Control, n = 6). Left panel: once tumors started growing, their sizes were measured twice weekly and tumor volume was calculated. Right panel: photographs of isolated tumors from each group. *P = 0.042. Student's t -test. (R) UHRF1 staining analysis of tissue sections from celecoxib(CXB)-treated and solvent(Control)-treated H22 tumor bearing mice (n = 6 per group). Scale bar, 1 cm. *P = 0.022. Student's t -test. (S) Schematic model showing the interactions between TAMs and HCC cells. TAMs produce and release PGE 2 into the tumor microenvironment. (I) PGE 2 inhibits miR-520 transcription by dissociating KLF6 from the miR-520 promoter. (II) Reduced miR-520 permits UHRF1 upregulation. (III) High-level UHRF1 epigenetically suppresses KLF6 expression via H3K9 hypermethylation. (IV) Dampened KLF6 lowers miR-520, thus allowing further elevation of UHRF1 protein level. (V) Concurrently, high-level UHRF1 epigenetically promotes CSF1 expression via DNA hypomethylation. (VI) CSF1 secreted from HCC cells promotes COX-2 expression in TAMs, leading to macrophage tumor infiltration and activation. The upregulated COX-2 in TAMs stimulates additional PGE 2 production .
Article Snippet: Protein extracts were probed with antibodies against human UHRF1 (sc-373750, Santa Cruz biotechnology, USA), KLF6 (sc-7158, Santa Cruz biotechnology, USA), COX-2 (A5787, ABclonal, USA), CSF1 (AF216, R&D Systems, USA), DNMT1 (sc-271729, Santa Cruz biotechnology, USA), and CCL14 (MAB3241, R&D Systems, USA) or β-actin (A5441, Sigma, USA).
Techniques: Staining, Expressing, Control, shRNA, Incubation, Plasmid Preparation, Stable Transfection, Cell Culture, DNA Methylation Assay, Methylation, Transfection, Injection, Liposomes, Solvent, Isolation, Activation Assay