preproenkephalin and Pancreatic-Neoplasms

Topics: Biomarkers, Tumor; Diagnosis, Differential; DNA; DNA Methylation; DNA-Binding Proteins; Early Diagnosis; Enkephalins; Exons; Genes, p53; Genes, ras; Membrane Proteins; Molecular Diagnostic Techniques; Mutation; Pancreatic Juice; Pancreatic Neoplasms; Protein Precursors; RNA, Messenger; Telomerase

Emodin, a natural anthraquinone derivative isolated from Rheum palmatum, has been reported to inhibit the growth of pancreatic cancer cells through different modes of action; yet, the detailed mechanism remains unclear. In the present study, we hypothesized that emodin exerts its antitumor effect by participating in the regulation of the DNA methylation level. Our research showed that emodin inhibited the growth of pancreatic cancer PANC-1 cells in a dose- and time-dependent manner. Dot-blot results showed that 40 µM emodin significantly inhibited genomic 5 mC expression in the PANC-1 cells, and mRNA-Seq showed that different concentrations of emodin could alter the gene expression profile in the PANC-1 cells. BSP confirmed that the methylation levels of P16, RASSF1A and ppENK were decreased, while concomitantly the unmethylated status was increased. RT-PCR and western blotting results confirmed that the low expression or absence of expression of mRNA and protein in the PANC-1 cells was re-expressed following treatment with emodin. In conclusion, our study for the first time suggests that emodin inhibits pancreatic cancer cell growth, which may be related to the demethylation of tumor-suppressor genes. The related mechanism may be through the inhibition of methyltransferase expression.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p16; DNA Methylation; Emodin; Enkephalins; Gene Expression Regulation, Neoplastic; Humans; Neoplasm Proteins; NF-kappa B; Pancreatic Neoplasms; Protein Kinase Inhibitors; Protein Precursors; Tumor Suppressor Proteins

CpG islands of the promoter region of some genes are methylated in pancreatic cancer tissue and the detection of this methylation has been suggested to be useful in the diagnosis of various cancers. The aim of this study was to investigate whether the detection of methylated CpG islands in plasma can be used in the diagnosis of pancreatic cancer.. Plasma DNA was collected from patients with pancreatic cancer, chronic pancreatitis, and healthy controls. The methylation status of six genes, UCHL1, NPTX2, SARP2, ppENK, p16, and RASSF1A, was checked by methylation-specific PCR and was subsequently confirmed by direct sequencing after bisulfite treatment.. CpG island methylation was detectable in 13 of 16 patients (81.3%) with pancreatic cancer, 1 of 29 healthy controls (3.5%), and 8 of 13 patients with chronic pancreatitis (61.5%). The mean number of genes with CpG island methylation was 1.6±1.2 in pancreatic cancer, 0.04±0.19 in healthy controls, and 1.2±1.1 in chronic pancreatitis. Among six genes, p16 was more specifically methylated in pancreatic cancer compared with chronic pancreatitis (p=0.016). The methylation status was not correlated with smoking history, tumor size, or cancer stage.. The detection of methylated genes in the plasma may have a role in differentiating between pancreatic cancers and healthy controls but not between pancreatic cancer and chronic pancreatitis.

Topics: Adult; Aged; Biomarkers, Tumor; C-Reactive Protein; Carcinoma, Pancreatic Ductal; Carrier Proteins; Cell Line, Tumor; CpG Islands; DNA Methylation; Enkephalins; Female; Genes, p16; Humans; Intercellular Signaling Peptides and Proteins; Male; Membrane Proteins; Middle Aged; Nerve Tissue Proteins; Pancreatic Neoplasms; Pancreatitis, Chronic; Polymerase Chain Reaction; Protein Precursors; Tumor Suppressor Proteins; Ubiquitin Thiolesterase

To examine the profiles of K-ras mutations and p16 and preproenkephalin (ppENK) promoter hypermethylation and their associations with cigarette smoking in pancreatic cancer patients.. In plasma DNA of 83 patients with untreated primary pancreatic ductal adenocarcinoma, DNA hypermethylation was determined by methylation-specific polymerase chain reaction and K-ras codon 12 mutations by enriched-nested polymerase chain reaction followed by direct sequencing. Information on smoking exposure was collected by in-person interview. Pearson chi test and Fisher exact test were used in statistical analysis.. K-ras mutations, ppENK, and p16 promoter hypermethylation were detected in 32.5%, 29.3%, and 24.6% of the patients, respectively. Sixty-three percent (52/83) of patients exhibited at least one of the alterations. Smoking was associated with the presence of K-ras mutations (P = 0.003). A codon 12 G-to-A mutation was predominantly observed in regular smokers and in heavy smokers (pack-year of smoking > or =36). Smoking was not associated with p16 or ppENK hypermethylation.. These preliminary observations suggest that plasma DNA might be a useful surrogate in detecting genetic and epigenetic alterations of pancreatic cancer. The findings on the association between K-ras mutation and smoking were in consistency with previous studies. Further studies on environmental modulators of epigenetic changes in pancreatic cancer are warranted.

Topics: Adenocarcinoma; Adult; Aged; DNA Methylation; Enkephalins; Epigenesis, Genetic; Female; Gene Expression Regulation, Neoplastic; Genes, p16; Genes, ras; Genetic Predisposition to Disease; Humans; Male; Middle Aged; Mutation; Pancreatic Neoplasms; Promoter Regions, Genetic; Protein Precursors; Smoking

Aberrant methylation of CpG islands is a common mechanism for the dysregulation of tumor suppressor genes in a variety of human malignancies. Preproenkephalin ppENK) hypermethylation is recognized in 90% of pancreatic carcinoma (PCa) tissues, but not in normal pancreas. We analyzed ppENK hypermethylation in pure pancreatic juice (PPJ) in patients with PCa, intraductal papillary mucinous neoplasms (IPMN), and chronic pancreatitis (CP), and elucidated its usefulness as a marker in the diagnosis of PCa compared with p53 mutation.. PPJ was collected endoscopically from 28 patients with PCa, 15 patients with IPMN, and 20 patients with CP. DNA was extracted from the supernatant and the sediment of PPJ. Methylation-specific polymerase chain reaction was performed for hypermethylation analysis of ppENK. In addition, single-strand conformation polymorphism and direct sequencing were performed simultaneously to identify p53 mutations.. The incidence of ppENK hypermethylation in the supernatant and/or the sediment of PPJ was 50% (14 of 28) in patients with PCa. In contrast, the incidence of ppENK hypermethylation was 26.7% (4 of 15) in patients with IPMN, and 5% (1 of 20) in patients with CP (P < 0.002). The incidence of p53 mutations in the PPJ was 42.9% (12 of 28) in patients with PCa and 0% (0 of 20) in patients with CP. Furthermore, the incidence of ppENK hypermethylation and/or p53 mutations in the PPJ was enhanced to 67.9% (19 of 28) in patients with PCa in the combination assay.. These results suggest that ppENK hypermethylation in PPJ is specific for cancer, and the combination assay with p53 enhances the genetic diagnosis of PCa.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Carcinoma, Pancreatic Ductal; DNA Methylation; DNA Mutational Analysis; Enkephalins; Female; Genes, p53; Humans; Male; Middle Aged; Mutation; Pancreatic Juice; Pancreatic Neoplasms; Pancreatitis, Chronic; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Protein Precursors

A higher prevalence of epigenetic inactivation of tumor suppressor genes has been reported in cancer cell line populations compared to primary cancer populations. Cancer-related genes are commonly methylated in cancer cell lines but it is not known the extent to which tumor suppressor genes may be artificially methylated in vitro. We therefore examined 10 pancreatic cancer cell lines and corresponding primary tumors for aberrant DNA methylation of promoter CpG islands of eight genes and seven CpG islands. Using methylation-specific PCR (MSP), methylation was not detected at any of the 15 CpG islands in 15 normal pancreata or in an immortalized normal pancreatic duct epithelial (HPDE) cell line. Of 150 loci examined, 49 loci were methylated in both primary carcinomas and their corresponding cell lines, 95 loci were not methylated in either cell lines or their corresponding primary carcinomas. There were four loci methylated only in cell lines while another two loci were methylated only in primary carcinomas. Overall, the methylation status of primary carcinomas and their cell lines were concordant in 96% of cases (144 of 150) (J statistic; J=0.92, P<0.0001). We conclude that most of the DNA methylation of tumor suppressor genes observed in cancer cell lines is present in the primary carcinomas from which they were derived.

Topics: Adenocarcinoma; Calcium Channels, T-Type; Cell Line; CpG Islands; DNA Methylation; DNA, Neoplasm; Enkephalins; Genes, Tumor Suppressor; Humans; Neoplasm Proteins; Pancreatic Neoplasms; Polymerase Chain Reaction; Promoter Regions, Genetic; Protein Precursors; Receptors, Retinoic Acid; Thrombospondin 1; Tissue Inhibitor of Metalloproteinase-3; Tumor Cells, Cultured

Pancreatic intraductal neoplasia (PanIN) is thought to be the precursor to infiltrating pancreatic ductal adenocarcinoma. We have previously shown that the preproenkephalin (ppENK) and p16 genes are aberrantly methylated in pancreatic adenocarcinoma. In this study we define the methylation status of the ppENK and p16 genes in various grades of PanINs. One hundred seventy-four samples (28 nonneoplastic pancreatic epithelia, 7 reactive epithelia, 29 PanIN-1A, 48 PanIN-1B, 27 PanIN-2, 14 PanIN-3, 15 invasive ductal adenocarcinomas, and 6 miscellaneous pancreatic neoplasms) were microdissected from 29 formalin-fixed paraffin-embedded surgically resected pancreata, and were analyzed by methylation-specific polymerase chain reaction. Fourteen of 15 (93.3%) invasive pancreatic ductal adenocarcinomas showed methylation of the ppENK gene and 4 of 15 (26.7%) showed methylation of the p16 gene. Nonneoplastic pancreatic epithelia did not harbor methylation of either gene. The prevalence of methylation of the ppENK gene increased significantly with increasing PanIN grade. A similar nonsignificant trend was noted for p16 methylation. Aberrant methylation of the ppENK gene was found in 7.7% of PanIN-1A, 7.3% of PanIN-1B, 22.7% of PanIN-2, and 46.2% of PanIN-3. Aberrant methylation of the p16 gene was found in 12% of PanIN-1A, 2.6% of PanIN-1B, 4.5% of PanIN-2, and 21.4% of PanIN-3. All but one of the PanINs from the 14 pancreata without pancreatic carcinoma was unmethylated with respect to either the p16 or ppENK gene. Our results suggest that methylation-related inactivation of the ppENK and p16 genes is an intermediate or late event during pancreatic carcinogenesis. Because aberrant methylation of ppENK or p16 was more often detected in similar grade PanINs from patients with pancreatic carcinoma than in those with other pancreatic diseases, it may be a useful indicator of the potential malignancy of epithelial cells of the pancreas.

Topics: Aged; Aged, 80 and over; Carcinoma, Pancreatic Ductal; Chronic Disease; Cyclin-Dependent Kinase Inhibitor p16; DNA Methylation; DNA, Neoplasm; Enkephalins; Epithelium; Female; Humans; Male; Middle Aged; Neoplasm Invasiveness; Pancreas; Pancreatic Neoplasms; Pancreatitis; Protein Precursors

The functional abrogation of several tumor suppressor genes, including p16, DPC4, and p53, is a major mechanism underlying pancreatic ductal carcinogenesis. However, mutational inactivation of these genes is relatively uncommon in intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. We hypothesized that an alternative mechanism for gene inactivation (notably, transcriptional silencing by promoter methylation) could be important in the pathogenesis of IPMNs.. Using methylation-specific polymerase chain reaction, we analyzed the methylation status of 7 CpG islands previously identified as aberrantly methylated in pancreatic adenocarcinoma (including preproenkephalin [ppENK], p16, and thrombospondin 1) in 51 IPMNs of different histologic grades. The relationship between methylation status and expression was evaluated using reverse-transcription polymerase chain reaction for ppENK and immunohistochemistry for p16.. We found that more than 80% of the IPMNs exhibited hypermethylation of at least one of these CpG islands. Hypermethylation of ppENK and p16 was detected at a significant higher frequency in high-grade (in situ carcinoma) IPMNs than in low-grade (adenoma/borderline) IPMNs (ppENK, 82% vs. 28%, P = 0.0002; p16, 21% vs. 0%, P = 0.04). Furthermore, the average number of methylated loci was significantly higher in high-grade IPMNs than in low-grade IPMNs (2.4 vs. 0.9; P = 0.0008). Aberrant methylation of ppENK and p16 was associated with loss of expression.. These results suggest that de novo methylation of multiple CpG islands is one of the critical pathways that contributes to the malignant progression of IPMNs.

Topics: Adenocarcinoma, Mucinous; Adenocarcinoma, Papillary; Adenoma; Adult; Aged; Aged, 80 and over; Carcinoma in Situ; Carcinoma, Pancreatic Ductal; CpG Islands; DNA Methylation; Enkephalins; Female; Genes, p16; Humans; Male; Middle Aged; Pancreatic Neoplasms; Protein Precursors

To identify CpG islands differentially methylated in pancreatic adenocarcinoma, we used methylated CpG island amplification (MCA) coupled with representational difference analysis. Of 42 CpG islands identified by MCA/representational difference analysis, 7 CpG islands [methylated in carcinoma of the pancreas (MICP)] were differentially methylated in a panel of eight pancreatic cancer cell lines compared with normal pancreas. In a larger panel of 75 pancreatic adenocarcinomas, these 7 MICPs (ppENK, Cyclin G, ZBP, MICP25, 27, 36, and 38) were methylated in 93, 3, 9, 15, 48, 19, and 41% of cancers, respectively, by methylation-specific PCR but not in any of 15 normal pancreata. In pancreatic cancer cell lines, methylation of ppENK, a gene with known growth suppressive properties, was associated with transcriptional silencing that was reversible with 5-aza-2'-deoxycytidine treatment. Relationships between the methylation patterns of pancreatic adenocarcinomas and their clinicopathological features were also determined. Larger pancreatic cancers and those from older patients (P = 0.017) harbored more methylated loci than smaller tumors and those from younger patients (P = 0.017). ppENK, MICP25, and 27 were variably methylated in normal gastric, duodenal, and colonic mucosae. These data indicate that aberrant methylation of ppENK and its transcriptional repression is a common event in pancreatic carcinogenesis.

Topics: Adenocarcinoma; Adult; Aged; Aged, 80 and over; Antimetabolites, Antineoplastic; Azacitidine; CpG Islands; Cyclin G; Cyclin G1; Cyclins; DNA Methylation; Enkephalins; Humans; Microsatellite Repeats; Middle Aged; Pancreatic Neoplasms; Protein Precursors; Reverse Transcriptase Polymerase Chain Reaction

The tumor cell line beta TC3 has been established from insulinomas derived from transgenic mice carrying a hybrid insulin promoter-simian virus-40 tumor antigen gene. The beta TC3 cells express high steady state levels of proinsulin messenger RNA (mRNA). In this same cell line, we describe in the present study high expression levels of prodynorphin (pro-Dyn) mRNA and its derived peptides. By Northern blot analysis, the screening of 23 cell lines of endocrine (n = 10) and of nonendocrine (n = 13) origin revealed the presence of high levels of the 2.6-kilobase pro-Dyn transcript only in beta TC3 cells. The beta TC3 cells expressed levels of pro-Dyn mRNA comparable to those in rat tissues expressing pro-Dyn. Chromatographic and radioimmunological studies showed that pro-Dyn mRNA was translated and fully processed into opioid peptides with leucine-enkephalin (Leu-Enk)-extended sequences [dynorphin-A-(1-8), dynorphin-B-(1-13), and alpha-neo-endorphin]. The expression of the prohormone convertases was also examined in beta TC3 cells by Northern blot analysis. In addition to the ubiquitously expressed furin, beta TC3 cells have abundant levels of prohormone convertase-1 (PC1) and PC2 mRNAs, but undetectable levels of PACE4 or PC5 mRNAs. Incubation of beta TC3 cells with 8-bromo-cAMP for 24 h stimulated 3-fold both the pro-Dyn mRNA levels and the secretion of opioid peptides. In contrast to pro-Dyn mRNA, furin, PC1, and PC2 mRNA levels were not affected by 8-bromo-cAMP. The beta TC3 cells constitute a unique model to elucidate the biosynthetic pathway of pro-Dyn processing, to identify the proteolytic enzymes responsible for the production of pro-Dyn end products, and to assess the potential role of opioid peptides in the regulation of pancreatic function.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Animals; Enkephalins; Furin; Insulinoma; Mice; Pancreatic Neoplasms; Peptide Fragments; Protein Precursors; Protein Processing, Post-Translational; Radioimmunoassay; RNA, Messenger; Subtilisins; Tumor Cells, Cultured