Retrovirus-mediated gene transfer of human endostatin inhibits growth of human liver carcinoma cells SMMC7721 in nude mice.

AIM: To study the effect of human endostatin mediated by retroviral gene transfer on the growth of human hepatocarcinoma cell line SMMC7721 in nude mice.
METHODS: Human endostatin gene together with rat serum albumin signal peptide was transferred into human liver carcinoma SMMC7721 cells by retroviral vector pLncx to build a stable transfectant (SMMC-endo). PCR and Western blot analysis were used to verify the transfection and secretion of human endostatin gene in SMMC7721 cells. The endothelial cell proliferation assay in vitro was conducted to test the biological activity of the expressed human endostatin. The inhibitory effect of endostatin expressed by transfected SMMC7721 on the growth rates of tumor cells in vivo was observed. The mean microvessel density in the specimen was also counted.
RESULTS: PCR amplification proved that the genome of SMMC-endo cells contained a 550bp specific fragment of endostatin gene. Western blot analysis confirmed the secretion of human endostatin gene in the conditioned medium of transfected SMMC-endo cells. The endothelial proliferation assay showed that the conditioned medium of SMMC-endo cells significantly inhibited the proliferation of human umbilical vein endothelial cells by 48 %, significantly higher than that of SMMC-pLncx (10.2 %, P<0.01). In vitro experiments revealed that only in 3 out of 5 mice tumors were formed and the mean size of flank tumors from SMMC-endo cells was 94.5 % smaller than that from the control SMMC-pLncx cells 22 days after tumor inoculation (P<0.001). The mean microvessel density in tumor samples from SMMC-endo cells was only 8.6+/-1.1, much fewer than that of 22.6+/-4.5 from SMMC-pLncx cells (P<0.01).
CONCLUSION: Human endostatin mediated by retroviral gene transfer can inhibit human liver carcinoma cell SMMC7721 growth in nude mice.