OBJECTIVETo investigate the association of the methylation status and expression level of Syk gene with the clinicopathological characteristics in colorectal cancer (CRC) patients.

METHODSMethylation-specific PCR(MSP) and RT-PCR techniques were used to analyze the methylation status and expression level of Syk gene in cancer and normal tissues of 120 CRC patients, meanwhile, association of the methylation status and expression level of Syk gene with the clinicopathological characteristics and the prognosis were studied.

RESULTS(1) Syk gene expression was not found in 48 cancer tissues out of 120 patients and was found in all the normal tissues.The difference was significant. (2) Loss of Syk expression was found in 37 patients with Syk hypermethylation, and in 11 out of 83 patients with Syk nonmethylation. (3) The methylation status of Syk gene was correlated with the lymph node status and the Dukes stage, but not with other clinicopathological parameters. (4) The follow-up data revealed that the 3-year survival of patients with Syk hypermethylation was lower than that of patients without Syk hypermethylation(73.5% vs.95.7%,P=0.007),and postoperative recurrence rate significantly increased in the Syk hypermethylation group (32.4% vs. 8.4%,P=0.02).

CONCLUSIONHypermethylation leads to silence of Syk gene involved in the initiation of colorectal cancer, which increases the infiltration of colorectal cancer cells, postoperative relapse and decreases the postoperative 3-year survival time.