Michihiko Wada

N-Cadherin Expression and Epithelial-Mesenchymal Transition in Pancreatic Carcinoma

Purpose: Loss of intercellular adhesion and increased cell motility promote tumor cell invasion. In the present study, E- and N-cadherin, members of the classical cadherin family, are investigated as inducers of epithelial-to-mesenchymal transition (EMT) that is thought to play a fundamental role during the early steps of invasion and metastasis of carcinomas. Cell growth factors are known to regulate cell adhesion molecules. The purpose of the study presented here was to investigate whether a gain in N-cadherin in pancreatic cancer is involved in the process of metastasis via EMT and whether its expression is affected by growth factors. Experimental Design: We immunohistochemically examined the expression of N- and E-cadherins and vimentin, a mesenchymal marker, in pancreatic primary and metastatic tumors. Correlations among the expressions of N-cadherin, transforming growth factor (TGF)β, and fibroblast growth factor 2 was evaluated in both tumors, and the induction of cadherin and vimentin by growth factors was examined in cultured cell lines. Results: N-cadherin expression was observed in 13 of 30 primary tumors and in 8 of 15 metastatic tumors. N-cadherin expression correlated with neural invasion (P = 0.008), histological type (P = 0.043), fibroblast growth factor expression in primary tumors (P = 0.007), and TGF expression (P = 0.004) and vimentin (P = 0.01) in metastatic tumors. Vimentin, a mesenchymal marker, was observed in a few cancer cells of primary tumor but was substantially expressed in liver metastasis. TGF stimulated N-cadherin and vimentin protein expression and decreased E-cadherin expression of Panc-1 cells with morphological change. Conclusion: This study provided the morphological evidence of EMT in pancreatic carcinoma and revealed that overexpression of N-cadherin is involved in EMT and is affected by growth factors.

Expression of two angiogenic factors, vascular endothelial growth factor and platelet-derived endothelial cell growth factor in human pancreatic cancer, and its relationship to angiogenesis

Tumour angiogenesis, as assayed by microvessel density (MVD), and the expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) have become established as important prognostic indicators for many tumour types. In this study, MVD and the expression of VEGF and PD-ECGF were examined by immunohistochemical staining of 50 pancreatic cancer tissues, and the relationships between either MVD or the expression of these two angiogenic factors and the clinicopathological features, including survival, were analysed. The expression of VEGF and PD-ECGF proteins were confirmed by Western blot analysis and VEGF mRNA isoforms were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) in five pancreatic cancer cell lines. Twenty-eight (56%) of 50 pancreatic cancers were positive for VEGF protein in cancer cells, and 16 (32%) showed strong PD-ECGF staining in cancer and infiltrating cells. VEGF121 and VEGF165 were identified as the predominant species produced in pancreatic cancer cells. The overexpression of VEGF and PD-ECGF protein significantly correlated with high MVD (P = 0.002, 0.044, respectively). Advanced stage of disease was significantly more frequent in patients with high MVD (P = 0.025). No significant association was found between the expression of VEGF or PD-ECGF and clinicopathological features, except for tumour histology. The expression of PD-ECGF correlated with poor survival (P = 0.011), but MVD and VEGF expression were not found to be useful for the prediction of overall survival. This study suggests that VEGF and PD-ECGF may play an important role in tumour angiogenesis, and that PD-ECGF expression seems to be useful for establishing prognoses for pancreatic cancer.

Involvement of matrix metalloproteinase‐2 activity in invasion and metastasis of pancreatic carcinoma

Activation of matrix metalloproteinase‐2 (MMP‐2) has been implicated in the progression, invasion, and metastasis of various cancers, but little information is available with regard to its role in pancreatic carcinoma with poor prognosis.

Immunohistochemical analysis of Bcl-2, Bax, Bcl-X, and Mcl-1 expression in pancreatic cancers.

Expression of several members of the Bcl-2 family proteins was investigated by means of both immunohistochemical analysis in 30 invasive ductal adenocarcinomas and 23 intraductal papillary-mucinous tumors (IPMTs) and immunoblot analysis in 6 cancer tissues and 7 pancreatic cancer cell lines. We found that Bcl-2 was expressed in 23%, Bax in 53%, Bcl-X in 90%, and Mcl-1 in 90% of the invasive ductal adenocarcinomas. In intraductal papillary-mucinous adenocarcinomas, the expression rate of Bax was 44% and those of Bcl-XL and Mcl-1 were 88%; these values were higher than those for intraductal papillary-mucinous adenomas. Immunoblot analysis identified Bcl-XL as the predominant form of the Bcl-X protein in both pancreatic cancer tissues and cell lines, and demonstrated that both Bcl-XL and Mcl-1 protein levels were uniformly high in all cell lines. These results suggest that an imbalance between antiapoptosis proteins (such as Bcl-2, Bcl-XL, and Mcl-1) and proapoptotic proteins (such as Bax and Bcl-Xs) is involved in the distinctive biologic features of adenocarcinomas of the pancreas. Furthermore, predominantly high expressions of Bcl-XL and Mcl-1 in intraductal papillary-mucinous adenocarcinomas might be involved in the carcinogenesis in IPMT of the pancreas.

Role of Bcl-2 family proteins (Bax, Bcl-2 and Bcl-X) on cellular susceptibility to radiation in pancreatic cancer cells

The aim of this study was to examine Bax, Bcl-2 and Bcl-XL proteins in human pancreatic cancer cell lines and to clarify the mechanism of radiation resistance. PANC-1 and AsPC-1 pancreatic cell lines were used, both having mutated p53. Radioresistant PANC-1/Rad cells and AsPC-1/Rad cells were obtained by repeated 5 Gy irradiation of PANC-1 cells and AsPC-1 cells, respectively. Radiation was found to inhibit the growth of PANC-1 cells and AsPC-1 cells. After exposure to radiation, detached cells were subjected to FITC-TUNEL staining to calcualte the ratio of apoptosis. TUNEL positive ratios increased dose-dependently in both cell lines. Western blotting showed that the basal level of the Bax/Bcl-2 ratio reflected the radiosensitivity of these cell lines, and Bax expression was obviously upregulated after irradiation in the presence of mutated p53, but Bcl-2 expression remained almost constant. Both PANC-1/Rad and AsPC-1/Rad cells had greater Bcl-XL expression than the parental cells, and the basal level of the Bax/Bcl-2 ratio was no longer predictive of radiosensitivity. Upregulated expression of Bax protein after irradiation was not related to induction of apoptosis in these cells, suggesting that overexpression of Bcl-XL and functional reconstruction of Bcl-2 family proteins are important factors in acquired radioresistance.

Immunohistochemical analysis of cyclooxygenase-2 expression in pancreatic tumors.

SummaryBackgroundA considerable amount of evidence collected from several experimental systems and clinical studies with nonsteroidal Anti-inflammatory drugs (NSAIDs) indicates that Cox-2 may play a major role in colorectal tumorigenesis, but little information about Cox-2 expression in pancreatic tumors is available. In this study, we investigated Cox-2 expression by means of both immunohistochemical analysis and immunoblot analysis in pancreatic tumors.MethodsFifty invasive ductal adenocarcinomas and 26 intraductal papillary-mucinous tumors (IPMTs) were used for immunohistochemical analysis, and five pancreatic cancer tissues and five pancreatic cancer cell lines for immunoblot analysis.ResultsCox-2 was expressed in 72% of the invasive ductal adenocarcinomas, 31% of intraductal papillary-mucinous adenocarcinomas, and none of intraductal papillary-mucinous adenomas. The expression rate of Cox-2 in intraductal papillary-mucinous adenocarcinomas was significantly higher than that in intraductal papillary-mucinous adenomas, and that in invasive ductal adenocarcinomas was significantly higher than that in intraductal papillary-mucinous carcinomas. However, there was no significant correlation between Cox-2 expression and the prognosis and clinicopathological factors. Immunoblot analysis identified Cox-2 in all of pancreatic cancer tissues and 60% of cell lines.ConclusionThe biological role of cyclooxygenase-2 (Cox-2) in carcinoma cells should be investigated with reference to the cancer progression of the pancreas.

Expression of integrin alphaVbeta3 in pancreatic carcinoma: relation to MMP-2 activation and lymph node metastasis.

INTRODUCTION Overexpression of integrin alphaVbeta3 had been demonstrated in various tumors. Studies have suggested that elevated levels of integrin alphaVbeta3 in melanoma cells are deeply involved in the mechanism of increased melanoma invasiveness. AIMS To examine the expression of integrin alphaVbeta3 in pancreatic carcinoma and to evaluate the correlation between integrin expression accompanied by MMP-2 activation and clinicopathologic factors. METHODOLOGY Integrin alphaVbeta3 specific antibody LM-609 was used for immunochemical analysis, and intracellular localization was determined in human pancreatic cancer cell lines cultured on vitronectin coating. Fifty pancreatic adenocarcinomas analyzed immunohistochemically and 26 frozen samples were analyzed gelatin-zymographically. RESULTS Two of three pancreatic cancer cell lines demonstrated integrin alphaVbeta3 immunofluorescence with a membranous pattern, and 29 of 50 pancreatic carcinomas showed positive immunostaining of tumor cells. There was no significant correlation between integrin alphaVbeta3 expression and tumor size, tumor grade, or peripancreatic invasion. However, primary tumors with lymph node metastasis featured significantly higher expression of integrin alphaVbeta3 than those without node metastasis. Tumors with high integrin alphaVbeta3 expression showed significantly higher MMP-2 activation ratios than did tumors with low expression. CONCLUSION Expression analysis in pancreatic cancer tissue demonstrated involvement of alphaVbeta3 integrin in lymph node metastasis rather than peripancreatic invasion. MMP-2 activation is linked, at least in part, to the expression of integrin alphaVbeta3 of pancreatic cancer cells.

Prognostic Implication of Para-aortic Lymph Node Metastasis in Resectable Pancreatic Cancer

BackgroundThe survival curve of patients who undergo surgical resection of pancreatic cancer displays a steep decline within 1 year and a relatively slow decline thereafter. The patients with a short survival time may have identifiable clinicopathologic factors that lead to rapid relapse.Study DesignWe analyzed clinicopathologic factors in 133 patients who underwent margin-negative pancreatoduodenectomy with extended radical lymphadenectomy for invasive ductal carcinoma of the pancreas to detect factors that could be responsible for the short survival.ResultsTumor size, invasion of the anterior pancreatic capsule, retroperitoneal invasion, portal venous invasion, major arterial invasion, and metastasis to the para-aortic lymph nodes were variables associated with survival time in univariate analysis. Metastasis to the para-aortic lymph nodes was the single independent factor with a significant association with mortality in multivariate analysis. Some 84% of the patients who had positive para-aortic lymph nodes died within 1 year, versus 46% of the patients with negative nodes.ConclusionsAlthough tumors that involve the para-aortic lymph nodes may technically be resectable, the expected postoperative survival time for most patients is less than 1 year. If para-aortic nodal metastasis is detected, alternative treatment strategies should be considered.

Induction of cell-cycle arrest and apoptosis by a novel retinobenzoic-acid derivative, TAC-101, in human pancreatic-cancer cells.

In this study, we investigated the effect of a novel retinobenzoic acid, 4‐[3,5‐bis (trimethylsilyl) benzamido] benzoic acid (TAC‐101), on the growth of 4 human pancreatic‐cancer cell lines; BxPC‐3, MIAPaCa‐2, CFPAC‐1 and AsPC‐1. TAC‐101 significantly inhibited the proliferation of BxPC‐3 and MIAPaCa‐2 cells in a time‐ and concentration‐dependent manner, but not the proliferation of AsPC‐1 cells. Furthermore, the anti‐proliferative effects of TAC‐101 on BxPC‐3 and MIAPaCa‐2 cells were stronger than those of all‐trans retinoic acid. Flow‐cytometric analyses indicated that treatment of BxPC‐3 with TAC‐101 strongly induces cell‐cycle arrest at the G1 phase. The cell‐cycle arrest induced by TAC‐101 was accompanied by reduction of retinoblastoma‐gene product (RB) phosphorylation and an increase of 2 cyclin‐dependent kinase (CDK) inhibitors, p21WAF1/Cip1 (p21) and p27Kip1 (p27). TAC‐101 also caused a decrease in cyclin A and thymidylate synthase, which are E2F‐regulated gene products. No changes were observed in the expression of cyclin D1, cyclin E on CDK2. In addition, Hoechst staining, gel electrophoresis and flow‐cytometric analysis indicated that a marked reduction in the number of BxPC‐3 cells with TAC‐101 was related to the induction of apoptosis. Our results suggest that TAC‐101 inhibits the growth of certain pancreatic‐cancer cells by means of G1‐phase cell‐cycle arrest resulting from the reduction of RB phosphorylation and the up‐regulation of p21 and p27 as well as the induction of apoptosis. TAC‐101 may therefore be a useful agent for new therapeutic strategies focusing on inhibition of pancreatic‐cancer‐cell proliferation. Int. J. Cancer 81:637–644, 1999.

Intravenous Calcium Injection Test Is a Novel Complementary Procedure in Differential Diagnosis for Gastrinoma

Abstract The current study evaluated efficacy of the intravenous calcium injection test as a new diagnostic approach to clarify the existence of gastrinoma, which often goes undetected with routine testing. Twenty-six patients with hypergastrinemia were studied. For the calcium injection test, blood samples were taken from 12 patients with hypergastrinemia (HG), and three healthy volunteers, and one patient with nonfunctioning endocrine tumor in the pancreas (control). We compared results of the calcium injection test with those of the secretin test and the selective arterial secretagogue injection (SASI) test. The SASI test with secretin was performed in 24 of 26 patients with hypergastrinemia, including 22 of 24 patients with Zollinger-Ellison syndrome (ZES). Accuracy in the diagnosis of tumor localization by the SASI test was 95% (21 of 22) in ZES patients. The secretin test was negative in 3 of 21 patients with ZES (14%). Either the secretin test or the SASI test was positive in 22 of 23 patients (96%). The calcium injection test was administered to 12 patients in the HG group and 4 controls. The HG group showed significantly higher serum gastrin levels than those of the control group in the calcium injection test. Eight of 10 ZES patients (80%) had a positive calcium injection test. We could diagnose gastrinomas in 100% of ZES patients by either the calcium injection test or the secretin test. We have thus confirmed the efficacy of the intravenous calcium injection test in the diagnosis of gastrinoma. The calcium injection test could become an adjunct in the diagnosis of gastrinoma, which often goes undetected with routine testing.