Promoter hypermethylation of DAP‐kinase is associated with poor survival in primary biliary tract carcinoma patients

Abstract

To clarify the clinicopathological significance of promoter hypermethylation of tumor suppressor and tumor-related genes in biliary tract carcinomas, we examined the promoter methylation status of multiple genes in primary biliary tract carcinomas. These consisted of carcinomas of the bile duct, gallbladder, and duodenal ampulla. Surgical specimens were obtained from a total of 37 patients with biliary tract carcinoma. The cohort consisted of 23 patients with bile duct carcinoma, 9 patients with gallbladder carcinoma, and 5 patients with ampullary carcinoma. The methylation status of CHFR, DAP-kinase, E-cadherin, hMLH1, p16, RASSF1A, and RUNX3 was examined by methylation-specific polymerase chain reaction (MSP). The correlation between methylation status and clinicopathological characteristics was then assessed. The methylation frequencies of CHFR, DAP-kinase, E-cadherin, hMLH1, p16, RASSF1A, and RUNX3 genes were 16.2%, 21.4%, 27.0%, 8.1%, 24.3%, 27.0%, and 56.8%, respectively, in primary biliary tract carcinomas. The number of methylated genes per sample was 2.17 ± ± ± ±0.28 (average ± ± ± ±SD) in bile duct carcinomas, 1.80 ± ± ± ±0.97 in ampullary carcinomas, and 0.89 ± ± ± ±0.35 in gallbladder carcinomas, with a statistically significant difference between bile duct carcinomas and gallbladder carcinomas (P = = = =0.02). As for clinicopathological significance, patients with a methylated RUNX3 promoter were significantly older than those with unmethylated RUNX3 (P = = = =0.01), and DAP-kinase methylation was more frequent in poorly differentiated tumors than in well to moderately differentiated ones (P = = = =0.04). The overall survival rate was significantly lower in patients with methylated DAP-kinase (P = = = =0.009) or RUNX3 (P = = = =0.034) compared to those with unmethylated genes. Furthermore, DAP-kinase methylation-positive status was independently associated with poor survival in multivariate analyses (hazard ratio = = = =8.71, P = = = =0.024). A significant proportion of primary biliary tract carcinomas exhibited promoter hypermethylation of tumor suppressor and tumor-related genes, although bile duct carcinomas are more prone to being affected by promoter methylation than are gallbladder carcinomas. Hypermethylation of DAP-kinase appears to be a significant prognostic factor in primary biliary tract carcinomas. iliary tract carcinoma is a disease with a poor prognosis. The 5-year survival rate is less than 25% for intra-and extrahepatic bile duct carcinoma, and 32% to 61% for gallbladder carcinoma, even after radical resection of the tumor.1-3) There is no effective therapy for biliary tract carcinomas except surgical resection. Moreover, the molecular-biological mechanisms of the development of biliary tract carcinomas are less well understood than those of carcinomas of the colon, stomach, and liver.DNA methylation is an important epigenetic mechanism for suppressing gene activity by changing the chromatin structure. 4,5) It has become clear that aberrant DNA methylation of promoter region CpG isl...

Two distinct pathways of p16 gene inactivation in gallbladder cancer

“…The frequency in our study was comparatively higher than that in previous studies. Previous studies have revealed that the frequency of p16 promoter hypermethylation is not associated with tumor progression and clinicopathological characteristics [30,31] . Similarly, we found that p16 hypermethylation was not associated with any clinicopathological features.…”

“…P r o m o t e r hy p e r m e t hy l a t i o n o f p 1 6 l e a d s t o inactivation of the gene in various cancers. In gallbladder cancer, the frequency of p16 promoter hypermethylation ranges from 24% to 56% [12,[29][30][31] . In our study, p16 hypermethylation was found in 72.5% (37/51) of the tumors.…”

Runx3 is required for the differentiation of lung epithelial cells and suppression of lung cancer

“…RUNX3 was also identified as one of the five most informative genes of the CpG island methylator phenotype of colorectal cancer (Weisenberger et al, 2006). In addition to gastric and colon cancer, RUNX3 is frequently inactivated in cancers of the lung, bladder, pancreas, liver, prostate, bile duct, breast, larynx, esophagus, and testicular yolk sac by either DNA hypermethylation or mislocalization of the protein in the cytoplasm (Kato et al, 2003;Goel et al, 2004;Kang et al, 2004;Li et al, 2004;Tozawa et al, 2004;Xiao and Liu, 2004;Ito et al, 2005;Kim et al, 2005b;Lau et al, 2006). Among the lung cancers, RUNX3 promoter hypermethylation is preferentially found in lung adenocarcinomas (Sato et al, 2006).…”

DAPk Protein Family and Cancer

“…41 Additionally, loss of DAP-kinase expression in pituitary tumors, biliary tract tumors and urinary tract and gastric cancers and hepatocellular carcinoma was associated with advanced tumor stage and aggressive phenotype. 33,[42][43][44][45][46] A survey of breast tumors revealed that DAPk hypermethylation was observed mostly in the invasive subtype of tumors and was associated with poor prognosis. 31,47 In brain metastases of various solid tumors, DAPk silencing by methylation was observed in the majority of cases.…”