Deep Sequencing of Cancer-Related Genes Revealed GNAS Mutations to Be Associated with Intraductal Papillary Mucinous Neoplasms and Its Main Pancreatic Duct Dilation

BackgroundTo clarify the genetic mutations associated with intraductal papillary mucinous neoplasms (IPMN) and IPMN-related pancreatic tumours, we conducted cancer-related gene profiling analyses using pure pancreatic juice and resected pancreatic tissues.MethodsPure pancreatic juice was collected from 152 patients [nine with a normal pancreas, 22 with chronic pancreatitis (CP), 39 with pancreatic ductal adenocarcinoma (PDAC), and 82 with IPMN], and resected tissues from the pancreas were collected from 48 patients (six IPMNs and 42 PDACs). The extracted DNA was amplified by multiplexed polymerase chain reaction (PCR) targeting 46 cancer-related genes containing 739 mutational hotspots. The mutations were analysed using a semiconductor-based DNA sequencer.ResultsAmong the 46 cancer-related genes, KRAS and GNAS mutations were most frequently detected in both PDAC and IPMN cases. In pure pancreatic juice, GNAS mutations were detected in 7.7% of PDAC cases and 41.5% of IPMN cases (pGNAS mutations (n = 3) were accompanied by IPMN. Multivariate analysis revealed that GNAS mutations in IPMN cases were associated with dilated main pancreatic ducts (MPD, p = 0.016), while no statistically independent associations with clinical variables were observed for KRAS mutations. In the resected pancreatic tissues, GNAS mutations were detected in 50% of PDAC cases concomitant with IPMN, 33.3% of PDAC cases derived from IPMN, and 66.7% of IPMN cases, while no GNAS mutations were detected in cases of PDAC without IPMN.ConclusionsThe GNAS mutation was specifically found in the cases with IPMN and it was speculated that some PDACs might be influenced by the concomitant but separately-located IPMN in their pathogenic mechanism. Furthermore, the GNAS mutation was significantly associated with MPD dilatation in IPMN cases, suggesting its role in mucus hypersecretion.背景 为明确与导管内乳头状黏液性肿瘤（intraductal papillary mucinous neoplasms, IPMN）及IPMN相关胰腺肿瘤相关的基因突变特征，本研究采用纯胰液与手术切除胰腺组织开展癌相关基因谱分析。方法 本研究共收集152例患者的纯胰液样本（其中胰腺正常者9例、慢性胰腺炎（chronic pancreatitis, CP）患者22例、胰腺导管腺癌（pancreatic ductal adenocarcinoma, PDAC）患者39例、IPMN患者82例），以及48例患者的手术切除胰腺组织样本（其中IPMN患者6例、PDAC患者42例）。提取的DNA通过针对46个癌相关基因（包含739个突变热点）的多重聚合酶链反应（multiplexed polymerase chain reaction, PCR）进行扩增，随后采用半导体DNA测序仪对突变情况进行分析。结果 在46个癌相关基因中，KRAS与GNAS突变在PDAC及IPMN病例中检出率最高。在纯胰液样本中，PDAC病例的GNAS突变检出率为7.7%，IPMN病例的检出率为41.5%；另有3例携带GNAS突变的病例伴发IPMN。多变量分析显示，IPMN病例中的GNAS突变与主胰管扩张（main pancreatic ducts, MPD）显著相关（p=0.016），而KRAS突变未显示出与临床变量存在统计学意义上的独立关联。在手术切除的胰腺组织样本中，伴发IPMN的PDAC病例中GNAS突变检出率为50%，源于IPMN的PDAC病例中为33.3%，IPMN病例中为66.7%；而无IPMN的PDAC病例未检出GNAS突变。结论 GNAS突变特异性地出现在伴发IPMN的病例中，提示部分PDAC的致病机制可能受到同时存在但位置独立的IPMN的影响。此外，IPMN病例中的GNAS突变与主胰管扩张显著相关，表明其在黏液过度分泌过程中发挥作用。