Inhibitory effect of endostatin gene therapy combined with phosphorus-32 colloid on tumour growth in Wistar rats

Eighty healthy male Wistar rats, aged 5 weeks, weighing 100–120 g, were utilized for establishing tumour-bearing models by immediate Walker-256 cancerous ascites injection and randomly divided to four groups (n=20) treated with 0.2 ml solution containing saline, (32)P-colloid (0.3 mCi), endostatin gene (20 μg), endostatin gene combined with colloid (32)P. The effect of endostatin combined with a small dose of (32)P-colloidal on tumour growth in vivo was evaluated and the potential mechanism underlying the combined therapy was explored. We found that (32)P-colloid combined with endostatin exhibited higher inhibitory effect upon tumour growth compared with application of (32)P-colloid or endostatin alone, although three therapies all significantly inhibited tumour growth compared with saline control group. The higher inhibitory effect of (32)P-colloid combined with endostatin upon tumour growth might be attributed to a synergistic effect of inhibiting angiogenesis by endostatin and inducing apoptosis by (32)P-colloid, as demonstrated by microvessel density (MVD) and apoptotic index (AI) measurement. Combined therapy of (32)P-colloid and endostatin probably serves as a novel and efficacious therapy of tumour growth.