Inhibition of Specificity Protein 1 Is Involved in Phloretin-Induced Suppression of Prostate Cancer

Figure 4

Phloretin inhibited the activities of EGFR and its downstream PI3K/AKT, MEK/ERK, and GSK3β pathways. (a) LNCaP and PC-3 cells were incubated with phloretin (0, 20, 50, and 100 μM) for 24 h and then harvested for western blot assays to check the protein levels of p-EGFR(Y1173), EGFR, p-PI3K, PI3K, p-AKT(S473), p-AKT(T308), AKT, p-GSK3β(S9), GSK3β, and β-actin (loading control). (b) LNCaP and PC-3 cells were treated with phloretin as above and then harvested for western blot assays to check the protein levels of p-C-RAF(S338), C-RAF, p-MEK(S217/S221), MEK, p-ERK1/2(T202/Y204), ERK1/2, and β-actin (loading control). (c) LNCaP and PC-3 cells were treated with phloretin and then harvested for western blot assay to check the protein levels of p-Sp1(T453), p-Sp1(T739), Sp1, and β-actin (loading control); the ratio of p-Sp1 levels vs. total Sp1 levels was quantified using ImageJ software. ; ; ^#.

(a)

(b)

(c)