Neuronal pentraxin II (NPTX2) is frequently down-regulated by promoter hypermethylation in pancreatic cancers.
BACKGROUND
Gene silencing via promoter hypermethylation plays a crucial role in the pathogenesis of cancers. Neuronal pentraxin II (NPTX2) has been observed to be hypermethylated in pancreatic cancers. Methylation of NPTX2 might provide a novel diagnostic marker for pancreatic cancers.


OBJECTIVE
The objective of this study is to investigate the abnormal patterns of DNA methylation of NPTX2 in pancreatic cancers, and its role in the transcriptional silencing of NPTX2.


METHODS
NPTX2 expression was detected by reverse-transcription polymerase chain reaction (RT-PCR), and the methylation status of NPTX2 was assessed by methylation-specific polymerase chain reaction (MSP). Immunohistochemistry was used to examine the NPTX2 protein expression. The pancreatic cancer cell lines were treated with the DNA methyltransferase inhibitor, histone deacetylase inhibitors, either alone or in combination.


RESULTS
The MSP analysis revealed that the promoter region of NPTX2 gene was largely unmethylated in normal pancreatic tissues, while NPTX2 was frequently hypermethylated in pancreatic cancer cells and in primary pancreatic carcinomas. Quantitative RT-PCR revealed that the mean mRNA expression level of NPTX2 in the pancreatic cancer tissues was significantly lower than that in the paired adjacent normal tissues (0.96 ± 0.91 vs. 2.78 ± 1.42, P < 0.001). Consistent with RT-PCR detection, treatment with 5Aza-dC resulted in different degrees of induction of NPTX2 protein in the various cancer cell lines.


CONCLUSIONS
We demonstrate that the NPTX2 protein is down-regulated in human primary pancreatic cancers and in pancreatic cancer cell lines. This study provides the first evidence that the down-regulation of NPTX2 tightly correlates with its promoter hypermethylation.
Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai 200433, China.
Ling
L
Zhang
Jun
J
Gao
Zhaoshen
Z
Li
Yanfang
Y
Gong
D000230:Adenocarcinoma / Q000378:metabolism*; D014408:Biomarkers, Tumor; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D008780:Methyltransferases / Q000037:antagonists & inhibitors; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000099153:Pentraxins
D014408:Biomarkers, Tumor; D002097:C-Reactive Protein; D008780:Methyltransferases; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000099153:Pentraxins