Fig. 5: Sildenafil prevents the oncogenic growth of GC by inhibiting PDE5 to directly activate PKG for the regulation of c-MYC and IL-6. | Communications Biology

Fig. 5: Sildenafil prevents the oncogenic growth of GC by inhibiting PDE5 to directly activate PKG for the regulation of c-MYC and IL-6.

From: Repurposing of phosphodiesterase-5 inhibitor sildenafil as a therapeutic agent to prevent gastric cancer growth through suppressing c-MYC stability for IL-6 transcription

Fig. 5

A A heatmap illustrated differentially expressed genes in the IL-6/JAK/STAT3 signaling pathway in PDE5-overexpressing GC cells after sildenafil treatment (150 μM) compared to vehicle control for 48 h. Red indicates upregulated expression, while blue indicates downregulated expression. B Western blotting analysis was performed on the indicated proteins in PDE5-overexpressing GC cells transfected with IL-6-knockdown siRNA and treated with sildenafil (150 μM) for 48 h. β-actin was used as a loading control. C The correlation among PDE5, IL-6, and c-MYC gene expression was analyzed by using the TCGA-STAD database. D, E Western blotting analysis assessed c-MYC and IL-6 expressions in PDE5-knockdown and PDE5-overexpressing GC cells treated with c-MYC-knockdown siRNA and sildenafil (150 μM) for 48 h respectively. F Primer sequences for the canonical c-MYC binding site. G A schematic representation of the IL-6 promoter shows the translational start site, with the regions indicated for luciferase reporter assays. H Luciferase activity analysis was conducted on the mutant fragments of the IL-6 promoter reporter vector after transfecting into GC cells and treated with sildenafil (150 μM) for 48 h. Data are presented from technical replicates (n = 3). I Chromatin immunoprecipitation using specific antibodies demonstrated the binding of c-MYC to the IL-6 promoter, with data shown from technical replicates (n = 5). J Western blotting analysis of the indicated proteins was conducted in PDE5-overexpressing GC cells treated with the PDE5 inhibitor sildenafil (150 μM), the PKG inhibitor KT5823 (20 μM), and the proteasome inhibitor MG132 (20 μM) for 48 h. K IHC staining of PDE5, c-MYC, and IL-6 expression in human GC tumor tissues, with scale bars of 200 μm (10×) and 20 μm (40×). L The correlation among PDE5, c-MYC, and IL-6 expression in human GC tumor tissues (n = 30) was analyzed. M A schematic diagram illustrated the key roles of the PDE5 inhibitor sildenafil in GC. This image and every element of this image were originally created and draw by using the BioRender online drawing website (https://biorender.com) after obtaining published permissions. Statistical significance is indicated as follows: ns, P-value > 0.05; *, P-value < 0.05; **, P-value < 0.01; ***, P-value < 0.001.

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