[Antitumor effect of recombinant immunotoxin EGF-TCS in nude mice bearing human hepatocellular carcinoma].

OBJECTIVE: To evaluate the anti-tumor effect of recombinant toxin EGF-TCS against transplanted human hepatocellular carcinoma in nude mice. METHODS: Human hepatocellular carcinoma BEL-7,402 cells were inoculated subcutaneously in the right axillary region of nude mice, and 6 days later, EGF-TCS was injected intravenously at 100, 50, and 25 microg/kg. The mice were executed on the next day of drug withdrawal and the tumors were weighed and the tumor inhibition rate calculated. Immunohistochemistry was also performed on the tumor tissues to provide clue for the possible pathways of tumor inhibition. RESULTS: EGF-TCS markedly inhibited the tumor growth in nude mice, with a tumor inhibition rate of 71.3%, 60.87% and 45.22% corresponding to EGF-TCS dosage of 100, 50, and 25 microg/kg, respectively. Variance analysis suggested that EGF-Linker-TCS could significantly inhibit the tumor growth in the mice (F=8.712, P=0.006), and immunohistochemistry showed significantly inhibited angiogenesis in the tumors by EGF-TCS. No blood vessels were found in the tumor tissues in high dosage group, and there were also reduced blood vessels in the other two smaller dose groups in comparison with the untreated model group, indicating that EGF-TCS inhibited tumor growth and migration by inhibiting tumor angiogenesis. CONCLUSION: EGF-TCS can inhibit the growth of solid tumors in nude mice, suggesting the potential value of this preparation in cancer therapy.

[Gene cloning, expression and purification of fusion protein epidermal growth factor-linker-trichosanthin].

OBJECTIVE: To construct a recombinant expression vector of the fusion protein epidermal growth factor (EGF)-Linker-trichosanthin (TCS) and achieve its expression in E. coli to obtain purified EGF-linker-TCS fusion protein. METHODS: The gene fragments of EGF-linker were amplified by PCR and inserted into the expression plasmid PQE30-TCS, followed by transformation of the recombinant plasmid into E. coli M15 for expression of the fusion protein. Ni-FF column chromatography was utilized for purification of the expressed product. RESULTS: The recombinant plasmid PQE30-EGF-linker-TCS was stably and highly expressed in E. coli M15. The expressed product existed in the form of soluble protein accounting for about 40% of total cellular protein and reached a purity of above 95% after purification with Ni-FF column chromatography. CONCLUSION: The recombinant plasmid PQE30/EGF-linker-TCS has been successfully constructed, which provides a basis for further structural and functional study of EGF and TCS and their potential clinical application for cancer therapy.