Objective    To express and purify EGF-TCS fusion protein and observe the targeted and selective killing effect on cancer cells of the fusion protein.     Methods    The recombinant expression plasmid PQE30/EGF-TCS was transformed to E. coli. M15 and the fusion protein (EGF-TCS) was expressed. Ni-NTA Agrose affinity chromatography was used to purify the protein

flow cytometry to detect EGFR expression rate in cancer cells (BEL-7402

MCF-7

BGC-823) and normal liver LO2 cells

and the killing test to verify selective killin

g ability of EGF-TCS; The cell apoptosis detection by flow cytometry and microscopic observation were used to confirm the selective killing ability of EGF-TCS.     Results    Recombinant expression plasmid PQE30/EGF-TCS was expressed in E. coli. M15 stably and effectively. The purity of EGF-TCS was over 95% by chromatography. EGFR expression rate was highest in hepatoma cells BEL-7402 (72.33%) and lowest in normal liver LO2 cells (5.51%). The killing ability of recombinant protein was more effective to cancer cells (IC

50

of BEL-7402

MCF-7 and BGC-823 was 11.4

22.47 and 12.53 μg/ml respectively) and was weak to normal cells (IC

50

53.19 μg/ml).     Conclusion    The recombinant protein EGF-TCS that induces apoptosis of cancer cells was successfully constructed by gene engineering technology.