Gene transfer of somatostatin receptor type 2 by intratumoral injection inhibits established pancreatic carcinoma xenografts

AIM: To investigate the therapeutic effect of somatostatin receptor type 2 (SSTR2) gene transfection on pancreatic carcinoma xenografts in vivo in experimental cancers. METHODS: Human pancreatic cancer cell line Panc-1 was inoculated subcutaneously into the back of nude mice. When tumor nodules were grown as large as about 5 mmx5 mm days after inoculation, the mice were randomly divided into 3 groups (6 mice in each group). Group I served as untreated control group. Group II received an intratumoral injection of a combination of human cytomegalovirus promoter-6C (pCMV-6C) and lipofectamine 2000. Group III received an intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000. The rate of tumor growth was compared among these three groups. The expression of SSTR2 in these tumors was detected by immunohistochemistry and Western-blot. Apoptosis index (AI) in these tumors was examined by using TUNEL in situ. RESULTS: Intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000 resulted in the expression of SSTR2 protein. The tumor size and weight in group III (0.318 +/- 0.098 cm(3), and 0.523 +/- 0.090 g, respectively) were significantly lower than those in group I (2.058 +/- 0.176 cm(3), and 1.412 +/- 0.146 g, respectively) and group II (2.025 +/- 0.163 cm(3), and 1.365 +/- 0.116 g, respectively) (P < 0.05) The AI in group III (1.47 +/- 0.13%) was significantly higher than that in group I (0.56 +/- 0.09%) and group II (0.57 +/- 0.11%) (P < 0.05). But there were no significant differences between groups I and II. CONCLUSION: Our data demonstrate that re-expression of SSTR2 gene has antitumor effects on experimental pancreatic cancer. Restoration of SSTR2 gene expression through gene transfer in vivo might be a potential gene therapy strategy for human pancreatic cancer. (C) 2005 The WJG Press and Elsevier Inc. All rights reserved.