Published online Jul 1, 2004. doi: 10.3748/wjg.v10.i13.1867
Revised: February 14, 2004
Accepted: February 21, 2004
Published online: July 1, 2004
AIM: To investigate the expression of adenovirus-mediated human endostatin (Ad/hEndo) gene transfer and its effect on the growth of hepatocellular carcinoma (HCC) BEL-7402 xenografted tumors.
METHODS: Immunohistochemistry analysis with an anti-endostatin antibody was preformed to detect endostatin protein expression in HCC BEL-7402 cells infected with Ad/hEndo. MTT assay was used to investigate the effects of Ad/hEndo on proliferation of human umbilical vein endothelial cells (HUVEC). Intra-tumoral injections of 1 × 109 pfu Ad/hEndo was given to treat BEL-7402 xenografted tumors in nude mice once weekly for 6 wk. Mice received injections of Ad/LacZ and DMEM were regarded as control groups. After intra-turmoral administration with Ad/hEndo, the endostatin mRNA expression in tumor tissue was analyzed by Northern blotting, and plasma endostatin levels were determined using enzyme-linked immunosorbent assay (ELISA).
RESULTS: High level expression of endostatin gene was detected in the infected HCC BEL-7402 cells. Ad/hEndo significantly inhibited HUVEC cell proliferation by 57.2% at a multiplicity of infection (MOI) of 20. After 6-week treatment with Ad/hEndo, the growth of treated tumors was inhibited by 46.50% compared to the Ad/LacZ control group (t = 2.729, P < 0.05) and by 48.56% compared to the DMEM control group (t = 2.485, P < 0.05). The ratio of mean tumor volume in treated animals to mean tumor volume in the control animals (T:C ratio) was less than 50% after 24 d of treatment. Endostatin mRNA in tumor tissue was clearly demonstrated as a band of approximately 1.2 kb, which was the expected size of intact and functional endostatin. Plasma endostatin levels peaked at 87.52 ± 8.34 ng/mL at d 3 after Ad/hEndo injection, which was significantly higher than the basal level (12.23 ± 2.54 ng/mL). By d 7, plasma levels dropped to nearly half the peak level (40.34 ± 4.80 ng/mL).
CONCLUSION: Adenovirus-mediated human endostatin gene can successfully express endogenous endostatin in vitro and in vivo, and significantly inhibit the growth of BEL-7402 xenografted liver tumors in nude mice.