Figure 5.

Effects of the peptides on breast cancer growth in a xenograft mouse model. (A) The experimental design of the mouse xenograft study. MB-MDA-231 cells (2 × 10⁶) were subcutaneously inoculated at the right or left flank of each BALB/c nude mouse. After the tumors developed to a volume of approximate 60–100 mm³, the mice were randomly divided into 3 groups with 7 mice in each group. The YPB, OPB, and Cont peptides were intratumorally injected into the tumors of the mice in the three groups correspondingly with a dosage of 30 μM in 100 µL per injection and injected every other day for 22 days. The mice were sacrificed 3 days after the last injection. (B,C) Tumor volumes (B) and their relative sizes (C) from the mice in the 3 groups after the initial peptide injection. (D) Image of actual xenograft tumors excised from the mice treated by the peptides. (E,F) The weights and volumes of the excised tumors after the mice were sacrificed. (G) The body weights of the mice in the 3 groups after the initial peptide injections. (H–J) Immunohistochemical analyses of xenograft tumors. Representative images of immunohistochemical staining using antibodies against Ki-67 (H), cleaved caspase3 (I), and cleaved PARP (J) are presented in the left panels, and their quantification was shown in the right panels. The quantification was carried out under 400× magnification in 3 randomly selected areas in each tumor, and the data shown are presented as mean ± SD of 3–5 tumor samples from individual mice in each group. Values represent the mean ± S.D., ** p < 0.01, *** p < 0.001.