OBJECTIVETo establish a green-fluorescent protein (GFP) labeled tumor metastasis model and to evaluate its biological characteristics.

METHODSHuman gastric carcinoma cell MGC-803 and murine cervical carcinoma cell U14 were transfected with the plasmid pEGFP-N1 and the efficiency of transfection was assessed 24 h later. Limited dilution was employed to screen and establish monoclonal cell strains, MGC-803-GFP and U14-GFP. The two fluorescent tumor cell stains were transplanted into BALB/c-nu mice and C57BL/6J mice respectively. The latency period of tumor mass appearance and the growth curve in vivo were documented. The tumor growth and metastasis were evaluated in vivo by the Viviperception Fluorescence Imagining System (VFIS). Expressions of CD44 and E-cadherin in tumor tissue were monitored by immunohistochemistry.

RESULTSThe efficiency of pEGFP-N1 transfection of MGC-803 cells and U14 cells were 30% and 60%, respectively. Monoclonal GFP(+) cell strains-MGC-803-GFP and U14-GFP were established. The latency periods of tumor formation of MGC-803-GFP and U14-GFP were 3-5 days and 2-4 days, respectively. Their tumorigenicity rates were 100% in both. The tumor growth of MGC-803-GFP was well defined by the VFIS. Only one mouse was shown to harbor lymphatic metastasis by VFIS, 60 days after transplantation. The metastasis process of U14-GFP was depicted through VFIS on 27, 37 and 52 days post-transplantation. The incidence of pulmonary metastasis and lymphatic metastasis of U14-GFP was 67% and 100% respectively when the tumor volume was >or=5 cm3. CD44 was positive and E-cadherin was negative in both tumors by immunohistochemistry.

CONCLUSIONSSuccessfully established two monoclonal tumor cell strains stably expressing GFP: MGC-803-GFP and U14-GFP. Transplantation of these cells into mice can establish tumor metastasis models which could be used for future visualized tumor research in vivo.