Preproenkephalin hypermethylation in the pure pancreatic juice compared with p53 mutation in the diagnosis of pancreatic carcinoma.
BACKGROUND
Aberrant methylation of CpG islands is a common mechanism for the dysregulation of tumor suppressor genes in a variety of human malignancies. Preproenkephalin ppENK) hypermethylation is recognized in 90% of pancreatic carcinoma (PCa) tissues, but not in normal pancreas. We analyzed ppENK hypermethylation in pure pancreatic juice (PPJ) in patients with PCa, intraductal papillary mucinous neoplasms (IPMN), and chronic pancreatitis (CP), and elucidated its usefulness as a marker in the diagnosis of PCa compared with p53 mutation.


METHODS
PPJ was collected endoscopically from 28 patients with PCa, 15 patients with IPMN, and 20 patients with CP. DNA was extracted from the supernatant and the sediment of PPJ. Methylation-specific polymerase chain reaction was performed for hypermethylation analysis of ppENK. In addition, single-strand conformation polymorphism and direct sequencing were performed simultaneously to identify p53 mutations.


RESULTS
The incidence of ppENK hypermethylation in the supernatant and/or the sediment of PPJ was 50% (14 of 28) in patients with PCa. In contrast, the incidence of ppENK hypermethylation was 26.7% (4 of 15) in patients with IPMN, and 5% (1 of 20) in patients with CP (P < 0.002). The incidence of p53 mutations in the PPJ was 42.9% (12 of 28) in patients with PCa and 0% (0 of 20) in patients with CP. Furthermore, the incidence of ppENK hypermethylation and/or p53 mutations in the PPJ was enhanced to 67.9% (19 of 28) in patients with PCa in the combination assay.


CONCLUSIONS
These results suggest that ppENK hypermethylation in PPJ is specific for cancer, and the combination assay with p53 enhances the genetic diagnosis of PCa.
Ohtsubo
Koushiro
K
Department of Internal Medicine and Medical Oncology, Cancer Research Institute, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan.
Watanabe
Hiroyuki
H
Yao
Fan
F
Okada
Gensaku
G
Mouri
Hisatsugu
H
Yamaguchi
Yasushi
Y
Sawabu
Norio
N
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D021441:Carcinoma, Pancreatic Ductal / Q000378:metabolism; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D016158:Genes, p53; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010189:Pancreatic Juice / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D050500:Pancreatitis, Chronic / Q000378:metabolism; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011498:Protein Precursors / Q000378:metabolism*
D014408:Biomarkers, Tumor; D004745:Enkephalins; D011498:Protein Precursors; C033660:preproenkephalin