AIM:To investigate human epidermal growth factor receptor 2(HER2)-phosphatidylinositol 3-kinase(PI3K)-vAkt murine thymoma viral oncogene homolog signaling pathway.METHODS:We analyzed 231 formalin-fixed,paraffinembedded gastric cancer tissue specimens from Japanese patients who had undergone surgical treatment.The patients' age,sex,tumor location,depth of invasion,pathological type,lymph node metastasis,and pathological stage were determined by a review of the medical records.Expression of HER2 was analyzed by immunohistochemistry(IHC) using the HercepTest TM kit.Standard criteria for HER2 positivity(0,1+,2+,and 3+) were used.Tumors that scored 3+ were considered HER2-positive.Expression of phospho Akt(pAkt) was also analyzed by IHC.Tumors were considered pAkt-positive when the percentage of positive tumor cells was 10% or more.PI3K,catalytic,alpha polypeptide(PIK3CA) mutations in exons 1,9 and 20 were analyzed by pyrosequencing.Epstein-Barr virus(EBV) infection was analyzed by in situ hybridization targeting EBV-encoded small RNA(EBER) with an EBER-RNA probe.Microsatellite instability(MSI) was analyzed by polymerase chain reaction using the mononucleotide markers BAT25 and BAT26.RESULTS:HER2 expression levels of 0,1+,2+ and 3+ were found in 167(72%),32(14%),12(5%) and 20(8.7%) samples,respectively.HER2 overexpression(IHC 3+) significantly correlated with intestinal histological type(15/20 vs 98 /205,P = 0.05).PIK3CA mutations were present in 20 cases(8.7%) and significantly correlated with MSI(10/20 vs 9/211,P < 0.01).The mutation frequency was high(21%) in T4 cancers and very low(6%) in T2 cancers.Mutations in exons 1,9 and 20 were detected in 5(2%),9(4%) and 7(3%) cases,respectively.Two new types of PIK3CA mutation,R88Q and R108H,were found in exon1.All PIK3CA mutations were heterozygous missense singlebase substitutions,the most common being H1047R(6/20,30%) in exon20.Eighteen cancers(8%) were EBV-positive and this positivity significantly correlated with a diffuse histological type(13/18 vs 93/198,P = 0.04).T
AIM:To evaluate the utility of measuring epigenetic alterations in pancreatic and biliary fluids in determining molecular markers for pancreatobiliary cancers.METHODS:DNA was extracted from undiluted pancreatic and bi...
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AIM:To evaluate the utility of measuring epigenetic alterations in pancreatic and biliary fluids in determining molecular markers for pancreatobiliary cancers.METHODS:DNA was extracted from undiluted pancreatic and biliary fluids.As a surrogate for a genomewide hypomethylation assay,levels of long interspersed nuclear element-1(LINE-1) methylation were analyzed using bisulfite pyrosequencing.CpG island hypermethylation of 10 tumor-associated genes,aryl-hydrocarbon receptor repressor,adenomatous polyposis coli,calcium channel,voltage dependent,T type α1G subunit,insulin-like growth factor 2,O-6-methyl-guanine-DNA methyltransferase,neurogenin 1,CDKN2A,runt-related transcription factor 3(RUNX3),secreted frizzled-related protein 1,and ubiquitin carboxyl-terminal esterase L1(UCHL1),was analyzed using MethyLight.To examine the role of CpG methylation and histone deacetylation in the silencing of UCHL1,human gallbladder carcinoma cell lines and pancreatic carcinoma cell lines were treated with 2 or 5 μmol/L 5-AZA-dC for 72 h or 100 nmol/L Trichostatin A for 24 h.After the treatment,UCHL1 expression was analyzed by real-time reverse transcription-polymerase chain reaction.RESULTS:Pancreatobiliary cancers exhibited significantly lower LINE-1 methylation levels in pancreatic and biliary fluids than did noncancerous pancreatobiliary disease(58.7% ± 4.3% vs 61.7% ± 2.2%,P = 0.027;53.8% ± 6.6% vs 57.5% ± 1.7%,P = 0.007);however,LINE-1 hypomethylation was more evident in pancreatic cancer tissues than in pancreatic fluids(45.4% ± 5.5% vs 58.7% ± 4.3%,P < 0.001).CpG island hypermethylation of tumor-associated genes was detected at various frequencies,but it was not correlated with LINE-1 hypomethylation.Hypermethylation of the UCHL1 gene was cancer-specific and most frequently detected in pancreatic(67%) or biliary(70%) fluids from patients with pancreatobiliary cancer.As a single marker,hypermethylation of the UCHL1 gene in pancreatic and biliary fluids was most useful for the detection of pancreatic and pancreatobiliary cance
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