Figure 2.

Effects of APT_STAT3-9R treatments on STAT3 phosphorylation, sensitivity to vemurafenib, and antitumor efficacy in melanomas

(A) Structure and characteristics of the cell-permeable STAT3-inhibiting peptide, APT_STAT3-9R. (B) Western blotting results for P-STAT3 (Tyr705), STAT3, and GAPDH in YUMM1.7P and YUMM1.7R cells pretreated with 10 μM APT_SCR-9R or APT_STAT3-9R for 2 h and subsequently treated with IL-6 (20 ng/mL). (C) Viability of YUMM1.7P and YUMM1.7R cells after treatment with increasing concentrations of either APT_STAT3-9R or APT_SCR-9R for 48 h. Representative results from one of three independent experiments are shown. Data are presented as means ± SEM (n = 5; ∗∗∗∗p < 0.0001, ∗∗p < 0.01; one-way ANOVA followed by Sidak’s post hoc test). (D) Viability of YUMM1.7R cells pretreated with 10 μM APT_STAT3-9R or APT_SCR-9R for 2 h and subsequently treated with vemurafenib (VEM; 5 μM) for 48 h. Representative results from one of three independent experiments are shown. Data are presented as means ± SEM (n = 5; ∗∗∗∗p < 0.0001; one-way ANOVA followed by Sidak’s post hoc test). (E) Schematic depiction of the experimental design. C57BL/6 mice were injected s.c. with YUMM1.7R cells (3 × 10⁵ cells). The mice were randomly allocated to each treatment group (n = 5 mice/group). (F) Growth curves of YUMM1.7R-derived melanoma tumors upon treatment with each modality. Tumor size is expressed as mean ± SEM (n = 5 mice/group; ∗∗∗p < 0.0001, ∗∗p < 0.01, ∗p < 0.05 versus untreated; two-way ANOVA followed by Tukey’s post hoc test). (G) Kaplan-Meier curves showing survival of each treatment condition (∗∗∗p < 0.0002, APT_STAT3-9R + VEM; Mantel-Cox log rank test). (H) Changes in body weight of each group were measured.