OBJECTIVETo evaluate the gene transfer and expression of enhanced green fluorescent protein (EGFP) in retrovirally transducted variant HT-29c cells in vitro and in vivo.

METHODSThe retroviral vector prkat EGFP/neo was constructed and was transfected into the 293T cell using a standard calcium phosphate precipitation method. HT-29c cells (in vivo selected HT-29 cells) were transduced by a retroviral vector encoding the EGFP gene. The fluorescence intensity of colorectal carcinoma HT-29c cells after transfected with the EGFP gene bearing retrovirus was visualized using fluorescence microscope and fluorescence activated cell sorter analysis. Multiple biological behaviors of transduced cells such as the proliferating potential and the expression of various antigens were comparatively analyzed between untransfected and transfected in vitro. EGFP expression of the fresh tumor tissue was assessed in vivo.

RESULTSAfter being transduced, HT-29c cells with the EGFP gene displayed a stable and long-term EGFP expression under the nonselective conditions in vitro. After culturing cells successively to passage 50 in vitro, EGFP expression level was still high. Their biological behaviors, such as expression of tumor antigens, proliferation rate and aggregation capability were not different compared to untransfected parental cells in vitro. In subcutaneous tumors, EGFP was stable and highly expressed.

CONCLUSIONSAn EGFP expressing retroviral vector was used to transduce HT-29c cells. The transduced cells show a stable and long-term EGFP expression in vitro and in vivo. These cells are a valuable tool for in vivo analysis of metastatic spread.