AIM: To explore the influence of angiostatin up-regulationon the biologic behavior of gastric cancer cells in vitro andin vivo, and the potential of angiostatin gene therapy in thetreatment of human gastric cancer.METHODS: Mouse angiostatin cDNA was subcloned intothe eukaryotic expression vector pcDNA3.1(+) and identifiedby restriction endonucleases digestion and sequencing. Therecombinant vector pcDNA3. 1(+)-angio was transfected intohuman gastric cancer cells SGC7901 with liposome andparalleled with the vector control and the mock control.Angiostatin transcription and protein expression wereexamined by RT-PCR and West blot in the stable celllines selected by G418. Cell proliferation and growth in vitroof the three groups were observed respectively undermicroscope, cell number counting and FACS. The cellsoverexpressing angiostatin, vector transfected and untreatedwere respectively implanted subcutaneously into nude mice.After 30days the size of tumors formed was measured, andmicrovessel density count (MVD) in the tumor tissues wasassessed by immunohistochemistry with the primary anti-vWF antibody.RESULTS: The recombinant vector pcDNA3.1(+)-angio wasconfirmed with the correct sequence of mouse angiostatinunder the promoter CMV. After 30 d of transfection andselection with G418, macroscopic resistant cell clones wereformed in the experimental group transfected with pcDNA3.1(+)-angio and the vector control. But no untreated cellssurvived in the mock control. Angiostatin mRNAtranscription and protein expression were detected in theexperimental group. No significant differences wereobserved among the three groups in cell morphology, cellgrowth curves and cell cycle phase distributions in vitro.However, in nude mice model, markedly inhibitedtumorigenesis and slowed tumor expansion were observedin the experimental group as compared with the controls,which was paralleled with decreased microvessel density inand around tumor tissues (P＜0. 05).CONCLUSION: Angiostatin does not directly inhibit humangastric cancer cell proliferation and growth in vitro, but exertsits anti-tumor functions through antiangiogenesis in aparacrine way in vivo.