Expression of the gene for a membrane-bound fatty acid receptor in the pancreas and islet cell tumours in humans: evidence for GPR40 expression in pancreatic beta cells and implications for insulin secretion.

AIMS/HYPOTHESIS: G protein-coupled receptor 40 (GPR40) is abundantly expressed in pancreatic beta cells in rodents, where it facilitates glucose-induced insulin secretion in response to mid- to long-chain fatty acids in vitro. However, GPR40 gene expression in humans has not been fully investigated, and little is known about the physiological and pathophysiological roles of GPR40 in humans. The aim of this study, therefore, was to examine GPR40 expression and its clinical implications in humans. METHODS: GPR40 mRNA expression in the human pancreas, pancreatic islets and islet cell tumours was analysed using TaqMan PCR. RESULTS: GPR40 mRNA was detected in all human pancreases collected intraoperatively. It was enriched approximately 20-fold in isolated islets freshly prepared from the pancreases of the same individuals. The estimated mRNA copy number for the GPR40 gene in pancreatic islets was comparable to those for genes encoding sulfonylurea receptor 1, glucagon-like peptide 1 receptor and somatostatin receptors, all of which are known to be expressed abundantly in the human pancreatic islet. A large amount of GPR40 mRNA was detected in insulinoma tissues, whereas mRNA expression was undetectable in glucagonoma or gastrinoma. The GPR40 mRNA level in the pancreas correlated with the insulinogenic index, which reflects beta cell function (r=0.82, p=0.044), but not with glucose levels during the OGTT, the insulin area under the OGTT curve or the index for the homeostasis model assessment of insulin resistance (HOMA-IR). CONCLUSIONS/INTERPRETATION: The present study provides evidence for GPR40 gene expression in pancreatic beta cells and implicates GPR40 in insulin secretion in humans.

Hand-assisted laparoscopic resection of serous cystadenoma of the pancreas.

It is difficult to exclude the possibility of malignancy of pancreatic cystic tumors because a biopsy of the pancreas is hard to obtain. The indication of open surgery for those cystic tumors without evidence of malignancy is controversial. Therefore, laparoscopic or laparoscopically assisted procedure would be an adequate choice of treatment for cystic tumors of the pancreas. Hand-assisted laparoscopic distal pancreatectomy with preservation of the spleen and the splenic artery and vein was performed for two cases of pancreatic cystic tumors. Three ports and one hand port were used. After careful dissection and accurate hemostasis between the pancreas and splenic vessels, laparoscopic distal pancreatectomy was carried out using an endoscopic linear stapler. There were no perioperative complications. The pathological diagnoses were oligocystic serous cystadenoma and solitary cystic serous cystadenoma, respectively. Hand-assisted, spleen-preserving laparoscopic distal pancreatectomy with preservation of the splenic artery and vein is a feasible procedure for the treatment of benign or borderline-malignant cystic lesions of the distal pancreas.

Carbohydrate antigens as a risk factor for hematogenous recurrence of esophageal squamous cell carcinoma patients.

The patients with hematogenous recurrence have a poor prognosis in esophageal squamous cell carcinoma (SCC). Recent developments have suggested the important role of sialyl Lewis A and X in the step of hematogenous metastasis. To evaluate the role of two carbohydrate antigens on hematogenous recurrence in esophageal SCC, we examined clinicopathological features and the expression of sialyl Lewis A and X in 125 patients retrospectively. Thirty-three out of 125 patients had hematogenous recurrence after curative esophagectomy. sLeA and sLex expression correlated with hematogenous recurrence (p=0.026, p=0.043 respectively), and sLeA expression was correlated with pM (lymph). Cox proportional hazards model and logistic regression analysis revealed that pN and pM lymph were significant prognostic factors and predictive factors of hematogenous recurrence in esophageal SCC. Although, neither sLeA nor sLeX were significant factors affecting survival in esophageal SCC, logistic regression analysis demonstrated that increased tumoral expression of sLeA and sLeX were risk factors of hematogenous recurrence in esophageal SCC. In conclusion, patients with lymph node metastasis, in particular those with distant lymph node metastasis, the expression of sLeA and sLeX may suggest a higher incidence of hematogenous recurrence in esophageal SCC. New strategies for specific inhibition of cancer cell attachment to vascular endothelial cells should be considered for the patients with the increased tumoral expression of either sLeA or sLeX.

Expression of angiogenic factors and apoptotic factors in leiomyosarcoma and leiomyoma.

Angiogenesis is essential for tumor growth and metastasis. Some angiogenic factors, such as vascular endothelial growth factor (VEGF), platelet-derived endothelial cell growth factor (PD-ECGF), transforming growth factor-alpha (TGF-alpha) and basic fibroblast growth factor (bFGF) are involved in increased angiogenic activity and disease progression in many carcinomas. However, there is little information regarding the association between angiogenic factors and leiomyosarcoma. Although there are abundant vessels in the sarcoma which enable it to easily receive nutrition and medicinal components, chemotherapy cannot effectively treat leiomyosarcoma. This means the resistance to anticancer drugs in leiomyosarcoma is very strong. However, the resistant mechanism is still unclear. In this study, expressions of VEGF, PD-ECGF, TGF-alpha, bFGF, intratumoral microvessel density (IMVD), and p53, Bcl-2 and Bax were examined by immunohistochemistry in 30 patients with leiomyosarcoma and 21 patients with leiomyoma. With regard to angiogenesis, PD-ECGF and TGF-alpha were closely associated with an increase in IMVD (p=0.012, 0.0196, respectively), and VEGF and PD-ECGF were significantly expressed in leiomyosarcoma compared with leiomyoma (p=0.041, 0.041, respectively). Although p53 expression in leiomyosarcoma was significantly higher than in leiomyoma (p=0.016), the frequency of p53 positivity was not so high (47%). On the other hand, the ratio of Bcl-2/Bax in leiomyosarcoma was significantly higher than that in leiomyoma (p=0.033). The findings of this study suggest that in leiomyosarcoma, angiogenic factors, such as PD-ECGF, VEGF and TGF-alpha expression may be involved in tumor angiogenesis, and the frequently high ratio of Bcl-2/Bax and expression of p53 gene mutation might be related to chemoresistance mechanism.

Suppression of N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in F344 rats by JTE-522, a selective COX-2 inhibitor.

Recent studies have demonstrated that overexpression of cyclooxygenase-2 (COX-2) and elevation of COX-2-mediated synthesis of prostaglandin E(2) (PGE(2)) were observed in various cancers including esophageal cancer, but their roles in carcinogenesis of the esophagi still remain unclear. To address the issue, we observed the reduction of N:-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in rat esophagi via JTE-522 (4-[4-cyclohexyl-2-methyloxazol-5-yl]-2-fluorobenzenesulfonamide), a selective COX-2 inhibitor. In this study, 54 F344 male rats were divided into nine groups; JTE-522 (3, 9 and 30 mg/kg) was administered orally. We also examined the effects of JTE-522 on COX-2 mRNA and synthesis of PGE(2). In the group in which JTE-522 was administered intermittently at a daily dose of 30 mg/kg, the number of NMBA-induced esophageal tumors per rat significantly reduced, to 62% (P< 0.05), but the size of the tumors was not significantly inhibited. In the group in which JTE-522 was administered continuously five times weekly for 24 weeks at a daily dose of 9 mg/kg, both the number and size of tumors significantly reduced, to 29 and 44%, respectively (P<0.05). Furthermore, JTE-522 suppressed not only tumor formation but also developing carcinomas (P<0.0021) [corrected]. In this study, treatment with NMBA alone resulted in an approximately 5-fold rise in expression of COX-2 mRNA detected by semi-quantitative RT-PCR analysis and an approximately 7-fold increase in the production of PGE(2) measured by ELISA compared with the normal esophageal mucosa. The up-regulated COX-2 expression did not decrease with the treatment of JTE-522 at the 3, 9 and 30 mg/kg doses; however, the increased levels of PGE(2) synthesis were significantly decreased by administering JTE-522 (P<0.01). Our study suggests that COX-2-mediated PGE(2) is important in NMBA-induced esophageal tumorigenesis in rats, and therefore may be a promising chemotherapeutic target for the prevention and treatment of esophageal cancer, especially with selective COX-2 inhibitors.

Lewis acid catalysis in a supercritical carbon dioxide (scCO2)-poly(ethylene glycol) derivatives (PEGs) system: remarkable effect of PEGS as additives on reactivity of Ln(OTf)3-catalyzed Mannich and aldol reactions in scCO2.

Use of poly(ethylene glycol) derivatives (PEGs) as additives in supercritical carbon dioxide (scCO2) was found to be effective for Mannich and aldol reactions of silyl enolates with aldehydes and imines, and formation of emulsions was observed in these systems.

Human gastrinoma cells express calcium-sensing receptor.

The intravenous calcium injection test has been reported to be useful for the diagnosis of gastrinoma. However, the mechanism underlying calcium-evoked gastrin release is not fully understood. We investigated the mechanism of calcium-stimulated gastrin release from gastrinoma cells in vitro with a particular focus on the calcium-sensing receptor (CaR). Human gastrinoma cells were taken from mechanically minced gastrinoma tissues obtained at surgery. In the perifusion system, high [Ca2+]o induced gastrin release from gastrinoma cells. As [Ca2+]o increased, [Ca2+]i rapidly increased, as monitored by fluorometry. The response was not inhibited by nifedipine, a blocker of the voltage-dependent calcium channel. Reverse transcriptase-polymerase chain reaction and subsequent Southern blot hybridization revealed the presence of the CaR gene in human gastrinoma tissues. Moreover, the expression of CaR in gastrinoma tissues was confirmed by immunohistochemistry. Our results demonstrated that CaR was expressed in human gastrinoma cells and could be involved in the mechanism of calcium-evoked gastrin release.

Curative resection of microgastrinomas based on the intraoperative secretin test.

The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.

The Epstein-Barr virus is rarely associated with esophageal cancer.

The Epstein-Barr virus is an agent that causes African Burkitt's lymphoma, infectious mononucleosis, and Hodgkin's disease. It is also related to nasopharyngeal carcinoma and gastric carcinoma. The aim of this study was to evaluate the prevalence of the Epstein-Barr virus in esophageal cancer. Polymerase chain reaction and in situ hybridization were used to detect the Epstein-Barr virus. We detected 103 Epstein-Barr virus positive cells out of 107 of KYSE 273 cells using first standard-PCR. Epstein-Barr virus DNA could not be detected in 30 of the esophageal squamous cell carcinoma cell lines and 2 of the Barrett's esophageal adenocarcinoma cell lines. Out of 77 esophageal cancer patients, 3 cases were found positive for Epstein-Barr virus DNA using polymerase chain reaction. However, by in situ hybridization we found signals in only 1 of the 3 cases, the signal was located in the infiltrating lymphocytes. The Epstein-Barr virus is rarely associated with esophageal cancer.