Figure 1.

B49 targets BST-2 in cancer cells to prevent cell adhesion in vitro and tumor growth in vivo. (A) Cartoon depiction of a non-targeting control peptide (Control, green) and a BST-2-targeting peptide (B49, gray). On the N-terminus, both peptides contain penetratin (CPP). (B) Adherence of E0771 shControl (shCTL, pink) and E0771 shBST-2 (blue) breast cancer cells to E0771 shControl monolayers pre-treated with vehicle (1:8 (v/v) acetonitrile:water) or with 200 ng/well of the Control peptide (green) or B49 peptide (gray). (C) Adherence of 4T1 shControl (shCTL, pink) and 4T1 shBST-2 (blue) breast cancer cells to 4T1 shControl monolayers pre-treated with vehicle (1:8 (v/v) acetonitrile:water) or with 200 ng/well of the Control peptide (green) or B49 peptide (gray). (D,E) Adherence of (D) 4T1 shCTL cells or (E) 4T1 shBST-2 cells to 4T1 shControl monolayers pre-treated with 0, 200, 400 or 600 ng/well of B49. (F) Tumor volume over time computed as TV = 0.5 (length × width²) from mice (n = 15) bearing 4T1 tumors treated with a control peptide (green) or with B49 (gray). Once tumors reached 100 mm³, mice were treated intratumorally every three days with 0.3 μg/μl of peptide at 0.33 μl/mm³ tumor. Y-axis is represented as a percentage were initial tumor volume prior to peptide treatments was set to 100%. Tumor volume (%) = (Tumor volume on day X * 100)/100 mm³). (G) Anti-tumor activity of Control and B49 peptide calculated by averaging the tumor volumes from day 10 to day 35 (experimental end-point). (H) Kaplan–Meier survival plot of mice bearing 4T1 tumors treated with Control or B49 peptides over the course of 35 days. Median survival time is shown for each group. Error bars correspond to SEM. Significance was taken at *P < 0.05, ***P < 0.001 and ****P < 0.0001. ns = not significant.