Fig. 5. Effect of GSE procyanidins and active constituent B2G2 on constitutively active and Jagged-1-induced cleaved Notch1 expression in human PCa cell lines.

A) Both GSE procyanidins and B2G2 cause a dose-dependent decrease in the expression of constitutively active cleaved-Notch1 protein levels in LNCaP, C4–2B, 22Rv1, PC3, and DU145 PCa cells (under 10% FBS culture conditions). B) Both GSE procyanidins and B2G2 inhibit Jagged1 (Notch1 ligand)-induced cleaved Notch1 levels in C4–2B and DU145 cells (under serum free culture conditions). GSE procyanidins or B2G2 were added 30 min after Jagged1 treatment. At the end of the treatments, both adherent and non-adherent cells were harvested and total cell lysates were prepared. Lysates were subjected to SDS-PAGE followed by Western immunoblotting. Equal protein loading was confirmed by stripping and re-probing the membranes with β-actin. C) Decrease in the protein expression of HES-1 after exposure of C4–2B and DU145 cells with either GSE procyanidins or B2G2. Representative IF staining photomicrographs (X600 magnification using confocal microscopy) with HES-1 and DAPI as nuclear stain are shown. C4–2B cells were treated with 5μg/mL GSE or 25μM B2G2 while DU145 cells were treated with 100μg/mL GSE or 100μM B2G2 for 24 hrs. C control; GSE, grape seed extract; B2G2, procyanidin B2 3,3″-di-O-gallate.