OBJECTIVETo investigate the effects of spleen tyrosine kinase (SYK) overexpression on proliferation and apoptosis of colorectal cancer cells and explore the possible mechanism.

METHODSThe mRNA expressions of SYK and Fra?1 in 10 clinical specimens of colorectal cancer and 10 adjacent tissues were measured with qRT?PCR, and their protein expressions were detected with Western blotting. The recombinant plasmid pcDNA.3.1?SYK was constructed and transfected into colorectal cancer cells to induce SYK overexpression, and the cell viability and proliferation were assessed using by MTT assay and BrdU assay, respectively; caspase?3 activity in the cells was evaluated with a commercial kit and the cell apoptosis was analyzed with Annexin?V FITC/PI assay.

RESULTSThe expressions of SYK were significantly decreased in colorectal cancer tissues and colorectal cancer cell lines. Transfection of pcDNA.3.1?SYK into the colorectal cancer cells induced obviously upregulated mRNA and protein expressions of SYK, which caused a significant suppression of the cell viability and proliferation and enhancement of the cell apoptosis along with a significant inhibition of Fra?1 expression.

CONCLUSIONs SYK overexpression inhibits the proliferation and promotes apoptosis of colorectal cancer cells, and these effects are possibly mediated by the regulation of Fra?1 expression by SYK.