The promoter methylation of death-associated protein kinase influences expressions of its mRNA and protein in tissue of gastric cancer / 中华消化杂志

ABSTRACT

Objective To investigate the regulation effect of promoter methylation of deathassociated protein kinase (DAPK) on mRNA and protein expression of DAPK in tissue of primary gastric cancer (GC). Methods The cancerous and noncancerous samples from 62 patients with GC were determined by RT-PCR for mRNA expression of DAPK. The DAPK promoter methylation was detected by methylation-specific PCR. The protein expression of DAPK in 34 patients with methylation was determined by Western blot. Results mRNA and protein expre.ssions of DAPK in cancerous tissues were reduced significantly compared to noncancerous tissues (0. 2863d±0. 2027 vs 0. 57364±0. 1968,0. 2616±0. 0913 vs 0. 65294±0. 1808, P＜0.01). Methylation frequency of DAPK in cancerous tissues was higher than that in noncancerous tissues (54.8% vs 17.7%, P＜0.01). Furthermore, DAPK mRNA expression was decreased in methylation group compared to unmethylation group (0.1399±0. 0835 vs 0. 46404±0. 1569, P＜0. 01). Moreover, a significant correlation was demonstrated between the TNM stage and DAPK promoter methylation (P = 0. 04). Conclusion Expression of DAPK is down-regulated in cancerous tissues at mRNA and protein levels. Low expression of DAPK is associated with hypermethylation of the promoter of DAPK gene.