Hypermethylation of multiple genes in pancreatic adenocarcinoma.
Hypermethylation of CpG islands is a common mechanism by which tumor suppressor genes are inactivated. We studied 45 pancreatic carcinomas and 14 normal pancreata for aberrant DNA methylation of CpG islands of multiple genes and clones using methylation-specific PCR (MSP) and bisulfite-modified sequencing. Using MSP, we detected aberrant methylation of at least one locus in 60% of carcinomas. The genes analyzed included RARbeta (methylated in 20%), p16 (18%), CACNA1G (16%), TIMP-3 (11%), E-cad (7%), THBS1 (7%), hMLH1 (4%), DAP kinase (2%), and MGMT (0%). In addition, aberrant methylation was found in three CpG islands (MINT31, -1, and -2) in 38, 38, and 14% of carcinomas, respectively. Hypermethylation was largely confined to the carcinomas with only three loci (E-cad, DAP kinase, and MINT2) harboring methylation in some normal pancreata (36, 21, and 14%, respectively). Simultaneous methylation of at least four loci was observed in 5 of 36 (14%) pancreatic adenocarcinomas. We defined this subgroup of pancreatic adenocarcinomas as "CpG island-methylator-phenotype positive (CIMP+)." Two of four carcinomas with microsatellite instability harbored promoter hypermethylation of hMLH1, and both cases were CIMP+. Thus, we conclude that many pancreatic carcinomas hypermethylate a small percentage of genes, whereas a subset displays a CIMP+ phenotype.
Ueki
T
T
Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA.
Toyota
M
M
Sohn
T
T
Yeo
C J
CJ
Issa
J P
JP
Hruban
R H
RH
Goggins
M
M
D000230:Adenocarcinoma / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins; D020747:Calcium Channels, T-Type / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D019175:DNA Methylation; D064550:Death-Associated Protein Kinases; D015226:Dinucleoside Phosphates / Q000737:chemistry; D006801:Humans; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics; D010179:Pancreas / Q000378:metabolism / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000235:genetics*; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000235:genetics; D019699:Thrombospondins / Q000235:genetics; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics; D014183:Transplantation, Heterologous
D051017:Apoptosis Regulatory Proteins; D020747:Calcium Channels, T-Type; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D064550:Death-Associated Protein Kinases; D015226:Dinucleoside Phosphates; D019853:O(6)-Methylguanine-DNA Methyltransferase; D018168:Receptors, Retinoic Acid; D019699:Thrombospondins; D019717:Tissue Inhibitor of Metalloproteinase-3; C082925:retinoic acid receptor beta; C015772:CpG dinucleotide