不同亚型的生长抑素受体在胃癌组织中的表达变化及临床诊断意义

Effect of somatostatin on expression of VEGF and bFGF in human gastric cancer xenografts in nude mice

AIM: To observe the effect of somatostatin on the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in subcutaneous xenografts derived from human gastric carcinoma SGC-7901 cells in nude mice.

METHODS: An animal model of human gastric cancer xenograft was established by subcutaneously implanting SGC-7901 cells in nude mice. Twenty-four nude mice were randomly divided into four groups and treated with normal saline (group A), octreotide (group B), high-dose somatostatin (group C) and low-dose somatostatin (group D) for three weeks, respectively. After treatment, the animals were killed to take the tumors. The expression of VEGF and bFGF was examined by immunohistochemistry and Western blot.

RESULTS: Immunohistochemical analysis indicated that the integral optical density (IOD)/area (/pix²) of VEGF in groups A-D were 0.644 ± 0.022, 0.549 ± 0.002, 0.345 ± 0.019 and 0.435 ± 0.018, respectively. The expression of VEGF protein in tumor tissue was significantly higher in group A than in the other three groups (P < 0.001). Compared with group B, the expression of VEGF was reduced more significantly in groups C and D (P < 0.001 for both). The IOD/area (/pix²) of bFGF in groups A-D were 0.723 ± 0.018, 0.558 ± 0.004, 0.288 ± 0.017 and 0.595 ± 0.011, respectively. The expression of bFGF protein in tumor tissue was significantly higher in group A than in the other three groups (P < 0.001). Compared with group B, the expression of bFGF was reduced more significantly only in group C (P < 0.001). Western blot analysis indicated that the relative expression of VEGF in groups A-D were 0.98 ± 0.02, 0.76 ± 0.02, 0.53 ± 0.01 and 0.53 ± 0.01, respectively. The relative expression of bFGF in groups A-D were 0.76 ± 0.02, 0.71 ± 0.02, 0.32 ± 0.01 and 0.51 ± 0.01, respectively. The expression of bFGF and VEGF protein was significantly higher in group A than in the other three groups (P < 0.001). Compared with group B, the expression of VEGF and bFGF was reduced more significantly in groups C and D (P < 0.001).

CONCLUSION: Somatostatin can down-regulate the expression of VEGF and bFGF in subcutaneous xenografts derived from human gastric carcinoma SGC-7901 cells in nude mice, and the effect is more obvious than that of octreotide.