OBJECTIVETo explore the relationship between SULF2 and WRN promoter methylation and chemosensitivity to irinotecan, and also the clinicopathological features in patients with gastric cancer.

METHODSThe chemosensitivity to irinotecan was tested by MTT assay. The methylation of SULF2 and WRN promoter in the fresh gastric cancer tissues was detected by methylation specific PCR. The differences of chemosensitivity and clinicopathological features of the methylation group were compared with that of the non-methylation group. The tumor growth in nude mice bearing human gastric cancer xenografts treated with CPT-11was also observed.

RESULTSThe methylation rates of SULF2 and WRN were 28.4% (29/102) and 23.5% (24/102), respectively. There were no significant association between promoter methylation and clinicopathological features of patients including age, gender, histologic type, lymphatic invasion, and TNM Stage. In all the 102 cases, there were 30 cases of irrinotecan-sensitive group, and 72 cases of the irrinotecan-resistant group. The SULF2 methylation rate was 46.7% (14/30)in the sensitive group, and 20.8% (15/72) in the resistant group (P = 0.008),The WRN methylation rate was 33.3% (10/30) in the sensitive group, and 19.4% (14/72) in the resistant group (P = 0.214). Gastric cancer tissues were more sensitive to irrinotecan when both the genes were methylated. The nude mice bearing human gastric cancer xenografts with SULF2 methylation were more sensitive to irrinotecan.

CONCLUSIONSThe detection of SULF2 and WRN promoter methylation may provide evidence for screening and targeting the most sensitive gastric cancer subpopulation suitable for personalized irrinotecan chemotherapy.