Influence of the DCC gene on proliferation and carcinoembryonic antigen expression in the human colorectal cancer cell line SW1116.

This study investigated the effects of stable transfection of the exogenous wild-type DCC gene on growth of the human colorectal carcinoma cell line SW1116 in vitro. The DCC gene was amplified from normal human colon tissue by reverse transcription-polymerase chain reaction and used to construct a recombinant expression plasmid, pcDNA3.1(+)-DCC. DCC-negative SW1116 cells were transfected with pcDNA3.1(+)-DCC. Cell viability was tested by the methyl thiazolyl tetrazolium (MTT) assay. Immunofluorescence staining was used to determine the effects of pcDNA3.1(+)-DCC on carcinoembryonic antigen (CEA) expression in transfected cells. The number of cells in the population transfected with pcDNA3.1(+)-DCC was lower than in that transfected with the control pcDNA3.1(+) plasmid or in normal cells (t1 = 3.645, P1 < 0.05, t2 = 3.132, P2 < 0.05) at 3-6 days after transfection, and the proliferation rate of pcDNA3.1(+)-DCC transfected cells was also lower (t1 = 2.134, P2 < 0.05; t2 = 2.736, P2 < 0.05). The total viability of pcDNA3.1(+)-DCC transfected cells was lower than that of normal cells (t1 = 3.053, P1 < 0.05) at 2-6 days after transfection, and of control-transfected cells (t2 = 2.816, P2 < 0.05) after 2, 4, 5, and 6 days. The population of pcDNA3.1(+)-DCC transfected colored of green fluorescent cells and their fluorescent intensities were lower than those of control-transfected and normal cells. Therefore, the transfected DCC gene can suppress cell proliferation and lead to downregulation of CEA expression in SW1116 cells, which might weaken its infiltration and metastasis abilities.