Intraductal papillary mucinous neoplasm penetrating to the stomach, duodenum, and jejunum demonstrated on MR cholangiopancreatography with an oral negative contrast agent.

A 65-year-old man was referred to our hospital due to epigastric pain. Abdominal enhanced computed tomography (CT) demonstrated marked dilatation of the main pancreatic duct (MPD) and communication to the gastric and duodenal lumen was suspected. Esophagogastroduodenoscopy (EGD) showed a villous tumor with white mucous discharge in the posterior wall of the gastric corpus and duodenal bulb. Pathological specimens showed mucin-producing epithelium with nuclear atypia that had developed in a papillary form. Based on these findings, we diagnosed intraductal papillary mucinous neoplasm (IPMN) arising in the MPD with penetration into the gastric and duodenal lumen. Magnetic resonance cholangiopancreatography (MRCP) with an oral negative contrast agent (manganese chloride tetrahydrate) showed a fistulous tract not only to the stomach and duodenum, but also to the jejunum. MRCP demonstrated mucous streaming with remarkably high intensity. In this case, an oral negative contrast agent was useful to distinguish mucous discharge from gastric fluid, facilitating the diagnosis of penetration to the jejunum. This finding was unobtainable by CT or EGD. When IPMN penetrating to other organs is suspected, MRCP with an oral negative contrast agent may provide important information.

Bupropion can close KATP channel and induce insulin secretion.

Recently, a case of newborn infant with transient hyperinsulinism has been reported. This infant was reported to be free from typical perinatal risk factors of hyperinsulinism except for the fact that the mother of the baby was receiving the antidepressant bupropion during her pregnancy. However, the mother did not experience hyperinsulinism and, so far, there are no reports about the pharmacological mechanism of bupropion causing hyperinsulinemia. In this study, bupropion was shown to inhibit KATP channel activity in pancreatic ß-cell membranes and induce insulin secretion in relatively high concentration. This study shows, for the first time, that bupropion has a direct electrophysiological action on pancreatic ß-cells and can cause insulin secretion and also highlights the risk of using bupropion during pregnancy.

Alternate-day treatment with S-1 in patients with gastric cancer: a retrospective study of strategies for reducing toxicity.

BACKGROUND: In patients with adverse events of S-1, the dose is generally reduced or the treatment cycle is shortened. Whether the therapeutic effectiveness of modified regimens is similar to that of the standard dosage remains unclear. METHODS: We retrospectively studied patients with gastric cancer who received S-1 on alternate days. RESULTS: A total of 266 patients received S-1 on alternate days. In 116 patients, S-1 was initially given at the standard dosage but was switched to alternate-day treatment because of toxicity within 28 days on average. The other 150 patients initially received alternate-day treatment because of poor general condition. In the adjuvant chemotherapy group (n = 96), the 3-year survival rate was 88% in patients with stage II, 73% in stage IIIA, and 67% in stage IIIB who underwent D2 lymph-node dissection. In the palliative surgery group (n = 96), the response rate was 13%, with a median survival time (MST) of 624 days. In patients with unresectable/recurrent disease (n = 74), the response rate was 25%, with an MST of 338 days. Among the 116 patients who initially received treatment on consecutive days, 100% had grade 1, 53% had grade 2, and 5.2% had grade 3 adverse events. When S-1 was switched to alternate-day treatment, toxicity decreased in all patients. In the 266 patients who received alternate-day treatment, 8% had grade 1, 6% had grade 2, and 0% had grade 3 adverse events. CONCLUSION: Alternate-day treatment with S-1 may have milder adverse events without compromising therapeutic effectiveness.

Resolution of anti-neutrophil cytoplasmic antibody-associated vasculitis after resection of gastric cancer.

We report a case of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis in a 62-year-old patient with gastric cancer. The myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA) level was threefold above normal preoperatively. Vasculitis was seen on renal biopsy. Gastric resection revealed well-differentiated adenocarcinoma and vasculitis. The MPO-ANCA level returned to normal post-operatively. Although ANCA-associated vasculitis occasionally accompanies malignant tumors, this is the first documented case of concurrent gastric cancer-associated and ANCA-associated vasculitis, with post-operative resolution of the vasculitis.

CpG island methylation status in gastric carcinoma with and without infection of Epstein-Barr virus.

PURPOSE: EBV-associated gastric carcinoma shows global CpG island methylation of the promoter region of various cancer-related genes. To further clarify the significance of CpG island methylator phenotype (CIMP) status in gastric carcinoma, we investigated methylation profile and clinicopathologic features including overall survival in four subgroups defined by EBV infection and CIMP status: EBV-associated gastric carcinoma and EBV-negative/CIMP-high (H), EBV-intermediate (I), and EBV-negative (N) gastric carcinoma. EXPERIMENTAL DESIGN: Methylation-specific PCR was applied to 106 gastric carcinoma cases. CIMP-N, CIMP-I, and CIMP-H status was determined by the number (0, 1-3, and 4-5, respectively) of methylated marker genes (LOX, HRASLS, FLNc, HAND1, and TM), that were newly identified as highly methylated in gastric cancer cell lines. The methylation status of 10 other cancer-related genes (p14, p15, p16, p73, TIMP-3, E-cadherin, DAPK, GSTP1, hMLH1, and MGMT) was also evaluated. RESULTS: Nearly all (14 of 15) of EBV-associated gastric carcinoma exhibited CIMP-H, constituting a homogenous group (14%). EBV-negative gastric carcinoma consisted of CIMP-H (24%), CIMP-I (38%), and CIMP-N (24%). EBV-associated gastric carcinoma showed significantly higher frequencies of methylation of cancer-related genes (mean number +/- SD = 6.9 +/- 1.5) even if compared with EBV-negative/CIMP-H gastric carcinoma (3.5 +/- 1.8). Among EBV-negative gastric carcinoma subgroups, CIMP-H gastric carcinoma showed comparatively higher frequency of methylation than CIMP-I or CIMP-N, especially of p16 and hMLH1. CIMP-N gastric carcinoma predominantly consisted of advanced carcinoma with significantly higher frequency of lymph node metastasis. The prognosis of the patients of CIMP-N was significantly worse compared with other groups overall by univariate analysis (P = 0.0313). CONCLUSION: The methylation profile of five representative genes is useful to stratify gastric carcinomas into biologically different subgroups. EBV-associated gastric carcinoma showed global CpG island methylation, comprising a pathogenetically distinct subgroup in CIMP-H gastric carcinoma.

Soft and hard keratin expression in Epstein-Barr-virus-associated gastric carcinoma.

BACKGROUND: Epstein-Barr-virus-associated gastric carcinoma (EBVaGC) is a distinct subset of gastric carcinoma (GC). The expressions of cytokeratins (CK)7, 8, 18, 19 and 20 and truncated basic hair keratin 1 (hHb1-deltaN) were investigated in GC to clarify the characteristics of EBVaGC. MATERIALS AND METHODS: For immunohistochemical evaluation, 173 GC tissues were examined and 31 GC tissues and 5 GC cell lines were used for quantitative real-time RT-PCR (qrt-RT-PCR) and RT-PCR. RESULTS: EBVaGC showed significantly lower immunohistochemical positivity of CK7 (-/(+/-)/+/+ +/+ + +; 27/15/4/1/1) compared to EBV-negative GC (12/29/27/44/13), even after stratification by histological types. The qrt-RT-PCR test demonstrated decreased amounts of CK7, 18 and 19 mRNAs in EBVaGC. Two among 5 GC cell lines showed a decrease of CK7 mRNA level after recombinant EBV infection. hHb1-deltaN expression was not specific to EBVaGC. CONCLUSION: Abnormalities of CK7, 18 and 19 expressions, especially a decreased amount of CK7 expression, are characteristics of EBV-associated epithelial malignancies and might be important in carcinogenesis.

Pretreatment of gastric outlet obstruction with pancrelipase: Report of a case.

INTRODUCTION: Gastric outlet obstruction is characterized by the retention of gastric contents. Removal of gastric contents is an important part of the treatment strategy. The use of a nasogastric tube alone can result in inadequate removal of gastric contents. We treated a patient with advanced gastric cancer and gastric outlet obstruction with pancrelipase to aid in the removal of gastric contents. PRESENTATION OF CASE: The patient is an 81-year-old man with a Type 3 gastric cancer nearly circumferentially involving the antrum, resulting in gastric outlet obstruction. A nasogastric tube was placed for four days, but drainage of gastric contents was inadequate. Pancrelipase was then given orally for four days, and gastric contents were evacuated. The patient underwent distal gastrectomy with Roux-en-Y reconstruction and was discharged from the hospital on postoperative day 14. DISCUSSION: This report suggests that pancrelipase may be beneficial in the treatment of patients with gastric outlet obstruction. CONCLUSION: Pancrelipase allowed gastric contents to be evacuated in a short period of time in a patient with gastric outlet obstruction.

Oxytocinergic circuit from paraventricular and supraoptic nuclei to arcuate POMC neurons in hypothalamus.

Intracerebroventricular injection of oxytocin (Oxt), a neuropeptide produced in hypothalamic paraventricular (PVN) and supraoptic nuclei (SON), melanocortin-dependently suppresses feeding. However, the underlying neuronal pathway is unclear. This study aimed to determine whether Oxt regulates propiomelanocortin (POMC) neurons in the arcuate nucleus (ARC) of the hypothalamus. Intra-ARC injection of Oxt decreased food intake. Oxt increased cytosolic Ca(2+) in POMC neurons isolated from ARC. ARC POMC neurons expressed Oxt receptors and were contacted by Oxt terminals. Retrograde tracer study revealed the projection of PVN and SON Oxt neurons to ARC. These results demonstrate the novel oxytocinergic signaling from PVN/SON to ARC POMC, possibly regulating feeding.

Hexosamine pathway but not interstitial changes mediates glucotoxicity in pancreatic ß-cells as assessed by cytosolic Ca2+ response to glucose.

Hyperglycemia impairs insulin secretion as well as insulin action, being recognized as the glucotoxicity that accelerates diabetes. However, the mechanism underlying the glucotoxicity in pancreatic ß-cells is not thoroughly understood. Hyperglycemia alters glucose metabolism within ß-cells and interstitial conditions around ß-cells, including elevated osmolarity and increased concentrations of insulin and ATP released from overstimulated ß-cells. In this study, to explore direct effects of these alterations on ß-cells, single ß-cells isolated from rat islets were cultured for 3 days with high (22.3 mM) glucose (HG), compared with control 5.6 mM glucose, followed by their functional assessment by measuring cytosolic Ca2+ concentration ([Ca2+]i). The [Ca2+]i response to a physiological rise in glucose concentration to 8.3 mM was impaired in b-cells following culture with HG for 3 days, while it was preserved in ß-cells following culture with non-metabolizable L-glucose and with elevated osmolarity, insulin and ATP. This HG-induced impairment of [Ca2+]i response to 8.3 mM glucose was prevented by adding azaserine, a hexosamine pathway inhibitor, into HG culture. Conversely, culture with glucosamine, which increases the hexosamine pathway flux, impaired [Ca2+]i response to 8.3 mM glucose, mimicking HG. These results suggest that the HG-associated abnormal glucose metabolism through hexosamine pathway, but not elevated osmolarity, insulin and ATP, plays a major role in the glucotoxicity to impair the secretory function of pancreatic ß-cells.

Chronic phencyclidine treatment induces long-lasting glutamatergic activation of VTA dopamine neurons.

Use of phencyclidine (PCP) can mimic some aspects of schizophrenia. However, the underlying mechanism is unclear. Administration of PCP is known to activate mesolimbic dopamine pathway. In this study, we focused on ventral tegmental area (VTA) of mesolimbic dopamine pathway as target of PCP for inducing schizophrenia-like symptoms. Single VTA neuron was isolated and its neural activity was monitored by measuring cytosolic Ca(2+) concentration ([Ca(2+)]i) followed by immunocytochemical identification of dopamine neurons. Administration of glutamate increased [Ca(2+)]i in dopamine neurons from control rats, and the [Ca(2+)]i increase was inhibited in the presence of PCP. In contrast, in VTA dopamine neurons from rats chronically treated with PCP for 7 days, administration of glutamate was able to induce [Ca(2+)]i increase in the presence of PCP. Furthermore, this glutamate-induced [Ca(2+)]i increase in the presence of PCP continued even after washout of glutamate and this effect lasted as long as PCP was present. This long-lasting glutamate-induced [Ca(2+)]i increase in the presence of PCP was not observed or significantly attenuated under Ca(2+) free condition and by N-type Ca(2+) channel blocker ω-conotoxin. The results indicate that chronic treatment with PCP reverses the acute PCP effect on VTA dopamine neurons from inhibitory to stimulatory tone, and consequently induces long-lasting activation of dopamine neurons by glutamate.

Paraventricular nucleus nesfatin-1 neurons are regulated by pituitary adenylate cyclase-activating polypeptide (PACAP).

Nesfatin-1 is a neuropeptide localized in hypothalamic paraventricular nucleus (PVN). Previously, we have reported the mechanism of feeding suppression by nesfatin-1, and also reported the ability of nesfatin-1 in regulating stress response and the circadian feeding pattern. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide also related to the stress response, feeding, and regulation of cardiovascular and autonomic nervous systems. The neurons with receptors for PACAP are distributed in PVN. However, there are no reports showing the direct effect of PACAP on nesfatin-1 neurons. In order to explore the direct effect of PACAP on PVN nesfatin-1 neuron, we have measured the cytosolic free calcium ([Ca(2+)]i) using fura-2 microfluorometry in single neurons isolated from PVN of adult rats, followed by immunocytochemical identification of nesfatin-1 neurons. PACAP at 10(-15)M to 10(-9)M increased [Ca(2+)]i in dose dependent manner. PAC1 and VPAC2 receptor agonists also increased [Ca(2+)]i. Sixteen out of 40 neurons (40%) in PVN responded to 10(-9)M PACAP, and 12 out of 16 neurons (75%) which responded to 10(-9)M PACAP were found to be nesfatin-1 neurons. In this paper we show that PACAP directly activates nesfatin-1 neurons in PVN. The data suggest that nesfatin-1 controls feeding, stress response or autonomic response under PACAP regulation.

Clinicopathological study of lymph-node metastasis in 1,389 patients with early gastric cancer: assessment of indications for endoscopic resection.

BACKGROUND: The endoscopic resection of early gastric cancers (EGC) is a standard technique in Japan and is increasingly used throughout the world. Further experience in the treatment of EGC and a clearer delineation of the factors related to lymph-node metastasis would permit a more accurate assessment of endoscopic resection. METHODS: The study group comprised 1,389 patients with EGC who underwent gastrectomy with lymph-node dissection. We evaluated the relations of lymph-node metastasis to clinicopathological factors. RESULTS: Of the 718 patients with intramucosal carcinomas, 14 (1.9%) had lymph-node metastasis. All cases of lymph-node metastasis were associated with ulceration. No lymph-node metastasis was found in patients with intramucosal carcinomas without ulceration, irrespective of tumor size and histological type. Lymph-node metastasis was present in 14 (4.7%) of the 296 patients who had cancer with a submucosal invasion depth of less than 500 microm (sm1). Significantly increased rates of lymph-node metastasis were associated with undifferentiated types, ulcerated lesions and lymphatic invasion. No lymph-node metastasis was found in patients with differentiated sm1 carcinomas 30 mm or less in diameter without ulceration. Lymph-node metastasis occurred in 29% of the patients who had cancer with a submucosal invasion depth of 500 microm or more (sm2). CONCLUSION: This large series of patients with EGC provides further evidence supporting the expansion of indications for endoscopic treatment, as well as warns against potential risks.

Comparison of alternate-day versus consecutive-day treatment with S-1: assessment of tumor growth inhibition and toxicity reduction in gastric cancer cell lines in vitro and in vivo.

BACKGROUND: The toxic effects of S-1 can lead to discontinuation of treatment. Strategies for reducing toxicity without compromising therapeutic effectiveness are required. METHODS: We used the human gastric cancer cell lines MKN28 and MKN45 to examine such strategies in vitro. The cell lines were treated with three different regimens, given on alternate days (alternate-day) or on consecutive days (consecutive-day). On consecutive days, treatment A provided the same total dose as the alternate-day treatment, and treatment B was given for the same number of days as the alternate-day treatment. A fourth group served as control. In vitro, the relative inhibition (RI) of tumor growth by 5-fluorouracil was calculated using the 2-(2-methyl-4-nitrophenyl)-3-(4-nitrophyl)-5-2, 4-disulfophenyl)-2H-tetrazolium (WST-8) method. We also carried out an in vivo experiment in which tumor-bearing nude mice (BALBc/nu-nu) were used to examine the antitumor activity of S-1. Leukocyte counts and gastrointestinal mucosal injury were compared in mice that received alternate-day and consecutive-day treatments. RESULTS: In vitro, for MKN28, the RI was 22.9% for alternate-day, 34.1% for consecutive-day A, and 37.7% for consecutive-day B treatments. For MKN45, the RI was 51.1% for alternate-day, 52.2% for consecutive-day A, and 50.5% for consecutive-day B treatments. In vivo, for MKN28, the treated groups showed higher inhibition than the control, and inhibition of tumor growth was higher with alternate-day than with consecutive-day treatment. The RI was significantly higher with alternate-day (49.3%) than with consecutive-day treatment (16.2%; P < 0.05). For MKN45, the RI was greater than 50% in both treated groups. With consecutive-day treatment, 5 of the 14 mice used died during treatment. Leukocyte counts were lower in the mice with consecutive-day than with alternate-day treatment, or control. Atrophic changes and inflammatory cell infiltration of the small intestinal mucosa were severe after consecutive-day, but minimal after alternate-day treatment. CONCLUSION: Experimentally, alternate-day treatment with S-1 is equivalent to consecutive-day treatment in terms of RI of tumor growth, with lower toxicity.

p73 gene promoter methylation in Epstein-Barr virus-associated gastric carcinoma.

To clarify the significance of p73 in Epstein-Barr virus (EBV)-associated gastric carcinoma (GC), the immunohistochemical expression and CpG-island methylation of p73 were evaluated in cancer tissues and adjacent nonneoplastic tissues of GC with and without EBV infection. Loss of p73 expression by immunohistochemistry was specific to EBV-associated GC (11/13) compared to EBV-negative GC (3/38), which was independent of abnormal p53 expression. With methylation-specific polymerase chain reaction (MSP), the aberrant methylation of p73 exon 1 was similarly specific to EBV-associated GC (12/13), and also rare in EBV-negative GC (2/38). Bisulfite sequencing for p73 exon 1 and its 5' region confirmed the MSP results, showing uniform and high-density methylation in EBV-associated GC. Comparative MSP analysis of p14, p16 and p73 methylation, using 20 cases each of formalin-fixed and paraffin-embedded tissues of early GC with and without EBV infection, confirmed 2 types of methylation: global methylation with increased rates (p14 and p16) and specific methylation of p73 in EBV-associated GC. In nonneoplastic mucosa, p14, p16 and p73 methylation occurred in both EBV-associated (8/33, 6/34 and 3/38, respectively) and EBV-negative GC (6/23, 4/35, and 1/35). p73 methylation was observed in the mucosa without H. pylori infection in all 4 samples. Loss of p73 expression through aberrant methylation of the p73 promoter occurs specifically in EBV-associated GC, together with the global methylation of p14 and p16. A specific type of gastritis, prone to a higher grade of atrophy and p73 methylation, may facilitate the development of EBV-associated GC.

Doxifluridine combined with weekly paclitaxel for second-line treatment in patients with gastric cancer resistant to TS-1.

BACKGROUND: Many patients with gastric cancer respond to TS-1, but some fail to respond or have recurrence. Second-line therapy is needed. METHODS: We performed a pilot study in patients with advanced gastric cancer who did not respond to TS-1 or who had disease recurrence. The patients received oral doxifluridine (600 mg/day) on days 1 to 21 and an intravenous infusion of paclitaxel (70 mg/m(2)) on days 7, 14, and 21 of a 28-day cycle. The treatment was repeated until disease progression or prohibitive toxicity. Response rate, duration of response, median survival time (MST), effects on pleural effusion, ascites, and other signs, and toxicity were evaluated. RESULTS: The study group comprised 52 patients. The response rate was 28%. The duration of response was 103 days. The MST after the start of second-line treatment was 175 days (95% confidence interval, 135 to 224 days). Pleural effusion or ascites resolved or decreased in 73% of the patients. Hair loss occurred in 32 patients (62%), and leukopenia developed in 28 (54%, grade 3 in 1 patient and grade 2 or lower in the others). The MST after the start of treatment with TS-1 was about 16 months. CONCLUSION: A combination of doxifluridine and weekly paclitaxel is expected to be an effective second-line treatment for gastric cancer not responding to TS-1, especially in patients with malignant ascites or pleural effusion. However, it remains unclear whether paclitaxel plus doxifluridine results in a better response and survival benefit than paclitaxel alone in this subgroup of patients. Further studies are therefore necessary.

Cancer risk to the gastric corpus in Japanese, its correlation with interleukin-1beta gene polymorphism (+3953*T) and Epstein-Barr virus infection.

Polymorphisms of interleukin-1 (IL-1) genes have been reported to modify the risk of gastric carcinoma (GC) in Caucasians. The significance of IL-1beta gene polymorphisms was evaluated in Japanese GC patients with or without infection of Helicobacter pylori and Epstein Barr virus (EBV) with special reference to the topographic features of GC. IL-1beta gene polymorphisms at positions -511 and +3953 were evaluated by PCR-RFLP and a penta-allelic polymorphism of IL-1RA by PCR in healthy controls (n = 103) and GC (n =140; corpus 95, antrum 45). EBV-infection was determined in the neoplastic tissues by EBER1 in situ hybridization, and H. pylori infection in nonneoplastic gastric mucosa by PCR targeting of the H. pylori urease A gene. GC consisted of EBV-associated (n = 24) and EBV-negative (n = 116) patients, whereas H. pylori infection was positive in 130 cases. Among IL-1beta gene polymorphisms, genotype IL-1beta+3953 C/T was more frequent in the EBV-negative (21%) and corpus GC (23%) patients, compared to the controls (10%), respectively, although there was no genotype IL-1beta+3953 T/T in either group. Thus, the effect of IL-1beta+3953 T was statistically significant in logistic regression models adjusted for age in EBV negativity (odds ratio [OR] 2.27, 95% confidence interval [CI] 1.02-5.05) and in the corpus GC (2.70, 1.19-6.12) with highest OR 3.55 (1.54-8.23) in EBV-negative corpus GC. There was no significant influence of IL-1 gene polymorphism in EBV-associated GC, but it occurred predominantly in the corpus (24/24) compared to EBV-negative GC (71/116) (p = 0.00002). There was no correlation between H. pylori infection and IL-1 gene polymorphism in GC. The cancer risk of the gastric corpus in Japanese is influenced by IL-1beta+3953 polymorphisms. On the other hand, the risk of EBV-associated GC, which occurs predominantly in the corpus, is not influenced by this pro-inflammatory polymorphism.

Promoter hypermethylation of E-cadherin and its abnormal expression in Epstein-Barr virus-associated gastric carcinoma.

Promoter hypermethylation of various tumor-related genes is extremely frequent in Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC). To investigate the significance of the promoter methylation in EBVaGC, we focused on one of the important proteins in the carcinogenesis of the stomach, E-cadherin. Methylation-specific PCR analysis (MSP) was applied to surgically resected gastric carcinomas, together with immunohistochemistry, PCR-based analysis of mutations and allelic loss, and site-specific MSP of E-cadherin gene. By MSP, nearly all of the carcinomas showed aberrant methylation of E-cadherin promoter in EBVaGC (21/22), and the frequency of this aberration was significantly higher than that in EBV-negative gastric carcinoma (GC; 45/81; p = 0.0003). According to immunohistochemistry of E-cadherin, the frequency of abnormal staining pattern in EBVaGC (87%) was comparable to that in the diffuse type (80%), but higher than that in the intestinal type of EBV-negative GC (47%). Promoter methylation was well correlated with abnormal staining pattern in EBVaGC, but not in EBV-negative GC. Neither mutation nor allelic loss of E-cadherin was observed in EBVaGC. Methylation status of E-cadherin within each carcinoma was heterogeneous as far as examined. Thus, in addition to the known association involving p16, we determined that promoter methylation-mediated silencing of E-cadherin gene was also closely associated with the development of EBVaGC, although it becomes heterogeneous within a given tumor along its progression.

High-density methylation of p14ARF and p16INK4A in Epstein-Barr virus-associated gastric carcinoma.

Promoter hypermethylation of various tumor-related genes is extremely frequent in gastric carcinoma (GC) associated with Epstein-Barr virus (EBV). To investigate the significance of the promoter methylation in this type of GC, we examined the methylation densities of the promoter regions of p14ARF and p16INK4A in EBV-associated (n=7) and EBV-negative (n=14) GC. Bisulfite sequencing demonstrated a high frequency of concurrent methylation of p14ARF and p16INK4A promoter regions in EBVaGC. Methylation was observed in all 29 CpG sites of p14ARF and all 16 sites of p16INK4A with equally high densities. In EBV-negative GC, the methylation profiles differed between the 2 genes. Promoter methylation was sporadic and variable in p14ARF, and only the last position of CpG in p14ARF was methylated at high frequency. High-density methylation in p16INK4A was observed in a subset of GC, but the first position of CpG was never methylated in EBV-negative GC. These findings suggest the presence of mechanisms of de novo and maintenance methylation specific to EBVaGC that might be associated with EBV infection.

Global and non-random CpG-island methylation in gastric carcinoma associated with Epstein-Barr virus.

DNA hypermethylation may play a primary role in the genesis of Epstein-Barr virus (EBV)-associated gastric carcinoma (GC) (EBVaGC). Methylation-specific PCR targeting CpG-islands demonstrated markedly increased methylation of specific genes, such as p14, p15 and p16 genes, in EBVaGC in vivo. A high frequency of methylation was observed in an EBVaGC strain of severe combined immunodeficiency mice, and the expression of methylated genes in the strain was apparently lower than the expression of the unmethylated genes in EBV-negative GC strains. Although over-expression of DNA methyltransferases (DNMTs) is known to be associated with some human cancers, real-time PCR demonstrated that DNMTs expression was suppressed in EBVaGC. The DNA methylation of specific genes, independently of DNMTs expression, may be important in the development of EBVaGC.

Reduced expression and promoter methylation of p16 gene in Epstein-Barr virus-associated gastric carcinoma.

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a unique type of gastric carcinoma (GC), which is considered to develop in a different pathway from EBV-negative GC. To evaluate a possible role of p16, an inhibitor of G1/S transition of the cell cycle, in the carcinogenesis of EBVaGC, p16-immunohistochemistry and methylation-specific PCR analysis (MSP) were applied to surgically resected gastric carcinomas. When the percentage of p16-positive cells in more than 1000 carcinoma cells was expressed as p16 labeling index (p16-LI), it ranged from 2.5 to 88.1 (mean 42.9+/-24.4) in 70 gastric carcinomas. EBVaGC showed significantly lower values (n=15, 26.1+/ -22.1) than EBV-negative GC (n=55, 47.5+/-23.2) (P=0.0036). Fresh frozen tissues of 55 gastric carcinomas (16 EBVaGC and 39 EBV-negative GC) were further subjected to MSP, to evaluate abnormal methylation of the promoter region of the p16 gene. The frequency of methylation was significantly higher in EBVaGC (14/16) than in EBV-negative GC (9/39) (<0.0001). The methylation-positive carcinomas showed significantly lower p16-LI (35.9+/-21.6) than the unmethylated ones (55.2+/-22.7) (P=0.0014). Thus, a marked decrease of p16 expression, caused by the aberrant methylation of the p16 gene promoter, is closely associated with the development of EBVaGC.