Mutant GNAS detected in duodenal collections of secretin-stimulated pancreatic juice indicates the presence or emergence of pancreatic cysts

ArticleinGut 62(7) · August 2012with36 Reads
DOI: 10.1136/gutjnl-2012-302823 · Source: PubMed
Abstract
Objective Pancreatic cysts are commonly detected in patients undergoing pancreatic imaging. Better approaches are needed to characterise these lesions. In this study we evaluated the utility of detecting mutant DNA in secretin-stimulated pancreatic juice. Design Secretin-stimulated pancreatic juice was collected from the duodenum of 291 subjects enrolled in Cancer of the Pancreas Screening trials at five US academic medical centres. The study population included subjects with a familial predisposition to pancreatic cancer who underwent pancreatic screening, and disease controls with normal pancreata, chronic pancreatitis, sporadic intraductal papillary mucinous neoplasm (IPMN) or other neoplasms. Somatic GNAS mutations (reported prevalence ∼66% of IPMNs) were measured using digital high-resolution melt-curve analysis and pyrosequencing. Results GNAS mutations were detected in secretin-stimulated pancreatic juice samples of 50 of 78 familial and sporadic cases of IPMN(s) (64.1%), 15 of 33 (45.5%) with only diminutive cysts (<5 mm), but none of 57 disease controls. GNAS mutations were also detected in five of 123 screened subjects without a pancreatic cyst. Among 97 subjects who had serial pancreatic evaluations, GNAS mutations detected in baseline juice samples predicted subsequent emergence or increasing size of pancreatic cysts. Conclusion Duodenal collections of secretin-stimulated pancreatic juice from patients with IPMNs have a similar prevalence of mutant GNAS to primary IPMNs, indicating that these samples are an excellent source of mutant DNA from the pancreas. The detection of GNAS mutations before an IPMN is visible suggests that analysis of pancreatic juice has the potential to help in the risk stratification and surveillance of patients undergoing pancreatic screening.
    • "There is a need to understand the molecular mechanisms responsible for pancreatic cancer development and progression in order to identify effective therapeutic targets for this disease and whenever possible ensure its early detection. Pancreatic ductal adenocarcinomas develop as a result of clonallyselected genetic events most commonly involving the genes KRAS, CDKN2A, TP53 and SMAD423456, less commonly ATM and others [3, 5, 7, 8], and for pancreatic ductal adenocarcinomas arising from intraductal papillary mucinous neoplasms, most commonly KRAS, CDKN2A, TP53, as well as GNAS and RNF4391011. Previous studies have demonstrated that aberrant expression of epigenetically regulated genes contributes to pancreatic cancer development and progression1213141516. "
    [Show abstract] [Hide abstract] ABSTRACT: To identify potentially important genes dysregulated in pancreatic cancer, we analyzed genome-wide transcriptional analysis of pancreatic cancers and normal pancreatic duct samples and identified the transcriptional coactivator, EYA2 (Drosophila Eyes Absent Homologue-2) as silenced in the majority of pancreatic cancers. We investigated the role of epigenetic mechanisms of EYA2 gene silencing in pancreatic cancers, performed in vitro and in vivo proliferation and migration assays to assess the effect of EYA2 silencing on tumor cell growth and metastasis formation, and expression analysis to identify genes transcriptionally regulated by EYA2. We found loss of tumoral Eya2 expression in 63% of pancreatic cancers (120/189 cases). Silencing of EYA2 expression in pancreatic cancer cell lines correlated with promoter methylation and histone deacetylation and was reversible with DNA methyltransferase and HDAC inhibitors. EYA2 knockdown in pancreatic cancer cell lines increased cell proliferation. Compared to parental pancreatic cancer cells, pancreatic cancers stably-expressing EYA2 grew more slowly and had fewer metastases in orthotopic models. The transcriptional changes after stable expression of EYA2 in pancreatic cancer cells included induction of genes in the TGFbeta pathway. Epigenetic silencing of EYA2 is a common event in pancreatic cancers and stable expression EYA2 limits the growth and metastases of pancreatic adenocarcinoma.
    Full-text · Article · Mar 2014
  • Article · Sep 2012
  • [Show abstract] [Hide abstract] ABSTRACT: Background & aims: Imaging tests can identify patients with pancreatic neoplastic cysts but not microscopic dysplasia. We investigated whether mutant TP53 can be detected in duodenal samples of secretin-stimulated pancreatic juice, and whether this assay can be used to screen for high-grade dysplasia and invasive pancreatic cancer. Methods: We determined the prevalence of mutant TP53 in microdissected pancreatic intraepithelial neoplasias (PanINs), intraductal papillary mucinous neoplasms (IPMNs), and invasive adenocarcinomas. TP53 mutations were quantified by digital high-resolution melt-curve analysis and sequencing of secretin-stimulated pancreatic juice samples, collected from duodena of 180 subjects enrolled in Cancer of the Pancreas Screening trials; patients were enrolled because of familial and/or inherited predisposition to pancreatic cancer, or as controls. Results: TP53 mutations were identified in 9.1% of intermediate-grade IPMNs (2 of 22), 17.8% of PanIN-2 (8 of 45), 38.1% of high-grade IPMNs (8 of 21), 47.6% of PanIN-3 (10 of 21), and 75% of invasive pancreatic adenocarcinomas (15 of 20); no TP53 mutations were found in PanIN-1 lesions or low-grade IPMNs. TP53 mutations were detected in duodenal samples of pancreatic juice from 29 of 43 patients with pancreatic ductal adenocarcinoma (67.4% sensitivity; 95% confidence interval, 0.52-0.80) and 4 of 8 patients with high-grade lesions (PanIN-3 and high-grade IPMN). No TP53 mutations were identified in samples from 58 controls or 55 screened individuals without evidence of advanced lesions. Conclusions: We detected mutant TP53 in secretin-stimulated pancreatic juice samples collected from duodena of patients with high-grade dysplasia or invasive pancreatic cancer. Tests for mutant TP53 might be developed to improve the diagnosis of and screening for pancreatic cancer and high-grade dysplasia. Clinical Trial numbers: NCT00438906 and NCT00714701.
    Article · Nov 2012
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