The characteristic and clinical value of SPARC CpG island methylation in pancreatic adenocarcinoma tissue

Abstract

Objective To assess the methylation patterns in CpG islands of SPARC genes and its relationship with clinicopathological parameters. Methods Bisulfite treatment of genomie DNA and sequencing analysis was used to study methylation patterns in the CpG islands of SPARC genes in fresh tissues from 6 cases of chronic pancreatitis, 6 normal pancreatic tissues, 17 pancreatic adenocarcinoma and the cancer adjacent tissues, as well as 6 normaI blood samples for normal control, and compared the results with clinicopathological parameters. Results WBC DNA showed no methylation of SPARC gene CpG islands. The methylation rates in CpG islands of SPARC genes in pancreatic adenocarcinoma, the cancer adjacent tissues, chronic pancreatitis and normal pancreatic groups (2, 3, 4, 5, 6, 7 CpG sites) were 61.6%, 47.1%, 37.5%, 24.7%, respectively. The methylation rates in CpG islands (1, 8, 9, 10, 11, 12 sites) were 52.0%, 28.7%, 16.7% and 0. The difference were statistically significant between the pancreatic adenocarcinoma and chronic pancreatitis as well as normal pancreas groups (P＜0.001), and the difference were not statistically significant between the pancreatic adenocarcinoma and the cancer adjacent tissues. CpG hypermethylation were not related to risk factors such as smoking, alcohol, history of CP, the tumor size, differentiation and TNM staging, lymph node metastasis. Conclusions CpG in SPARC gene extron 1 was hypermethylated in pancreatic cancer, and this may be an early event in the development of pancreatic cancer. Key words: Pancreatic neoplasms; SPARC; Methylation; CpG islands; Gene diagnosis