Specific targeting of HER2-positive human breast carcinoma SK-BR-3 cells by amygdaline-Z affibody conjugate.

Amygdalin induces apoptotic death in several carcinoma cells. Affibody is an engineered protein with a high affinity for human epidermal receptor 2 (HER2). We assessed the cytotoxic effects of the amygdalin-Z affibody conjugate on two breast carcinoma cell lines. The Z affibody gene was synthesized and transferred into E. coli BL21 as an expression host. After purification, the Z affibody was conjugated to amygdalin. The cytotoxic effects of amygdalin and its Z affibody conjugate on the SK-BR-3, with overexpression of HER2, and MCF-7 cells were evaluated by MTT assay. The effects of amygdalin and its conjugate on apoptotic death and expression of pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins were measured. Amygdalin individually showed a potent cytotoxic effect against both MCF-7 (IC = 14.2 mg ml) and SK-BR-3 cells (IC = 13.7 mg ml). However, the amygdalin-Z affibody conjugate had a more cytotoxic effect on SK-BR-3 (IC = 8.27 mg ml) than MCF-7 cells (IC = 19.8 mg ml). Amygdalin had a significant apoptotic effect on both cell lines and the effect of its conjugate on SK-BR-3 cells was significantly more potent than MCF-7 cells. Amygdalin increased Bax and decreased Bcl-2 expression in both cell lines. However, the effect of its conjugate on the Bax and Bcl-2 expression in SK-BR-3 was more potent than MCF-7 cells. In conclusion, the amygdalin-Z affibody conjugate may be considered as a valuable candidate for specific treatment of breast cancer patients with overexpression of HER2. However, further in vivo studies are required to explain the antitumoral effects of constructed amygdalin-Z affibody conjugate.