Cytotoxic Effects of a Novel tagged Apoptin on Breast Cancer Cell Lines

Abstract

Backgrounds: Apoptin can induce tumor cell-specific apoptosis in a broad range of human tumor cells and is a potential anticancer therapeutic candidate to kill tumor cells. Materials and Methods: We designed two structures of apoptin fusion protein, SUMO-PTD4-Apoptin, and PTD4-Apoptin. To express these fusion proteins, E. coli BL21(DE3) was employed. MTT assay, Flow cytometry, and cell cycle analysis were used to investigate the function of proteins on two breast cancer cell lines (MDA-MB-231 and MCF-7) and MCF 10A cell line (as normal cells). Results: Expression of the recombinant SUMO-PTD4-Apoptin and PTD4-Apoptin in E. coli BL21(DE3) was successful. MTT assay results showed that the IC50 was 6.4 µg/ml for SUMO-PTD4-Apoptin in MDA-MB-231 and was 9.3 after 24 h of treatment in MCF-7. The specific cytotoxicity in both cell lines is significant in comparison with MCF-10A, which is used as a normal cell line (IC50 = 29.4). The IC50 for PTD4-Apoptin was 11.07 µg/ml after 24 h of treatment in MDA-MB-231, while the IC50 of PTD4-Apoptin for MCF7 cells was not significantly different from normal cells. The flow cytometry analysis displayed a significant increment in the apoptosis and late apoptosis number in the MDA-MB-231 cells after treatment with SUMO-PTD4-Apoptin and PTD4-Apoptin protein. PTD4-Apoptin and SUMO-PTD4-Apoptin treatment of MDA-MB-231 cells caused a noteworthy increase in the G0-G1 phase and a reduction in the cell population of S and M/G2. Conclusion: This study demonstrates that the fusion of PTD4-Apoptin to SUMO-PTD4-Apoptin could provide an effective method to help enhance the expression and solubility of heterologous Apoptin in E. coli. BL21 (DE3).