Extracellular volume fraction using contrast-enhanced CT is useful in differentiating intrahepatic cholangiocellular carcinoma from hepatocellular carcinoma.

Objectives: To evaluate whether tumor extracellular volume fraction (fECV) on contrast-enhanced computed tomography (CT) aids in the differentiation between intrahepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC). Methods: In this retrospective study, 113 patients with pathologically confirmed ICC (n = 39) or HCC (n = 74) who had undergone preoperative contrast-enhanced CT were enrolled. Enhancement values of the tumor (Etumor) and aorta (Eaorta) were obtained in the precontrast and equilibrium phase CT images. fECV was calculated using the following equation: fECV [%] = Etumor/Eaorta × (100 - hematocrit [%]). fECV values were compared between the ICC and HCC groups using Welch's t-test. The diagnostic performance of fECV for differentiating ICC and HCC was assessed using receiver-operating characteristic (ROC) analysis. fECV and the CT imaging features of tumors were evaluated by two radiologists. Multivariate logistic regression analysis was performed to identify factors predicting a diagnosis of ICC. Results: Mean fECV was significantly higher in ICCs (43.8% ± 13.2%) than that in HCCs (31.6% ± 9.0%, p < 0.001). The area under the curve for differentiating ICC from HCC was 0.763 when the cutoff value of fECV was 41.5%. The multivariate analysis identified fECV (unit OR: 1.10; 95% CI: 1.01-1.21; p < 0.05), peripheral rim enhancement during the arterial phase (OR: 17.0; 95% CI: 1.29-225; p < 0.05), and absence of washout pattern (OR: 235; 95% CI: 14.03-3933; p < 0.001) as independent CT features for differentiating between the two tumor types. Conclusions: A high value of fECV, peripheral rim enhancement during the arterial phase, and absence of washout pattern were independent factors in the differentiation of ICC from HCC.

Insulinoma induces a hyperinsulinemia-mediated decrease of GLUT2 and GLP1 receptor in normal pancreatic ß-cells.

There have been several clinical reports of transient postoperative hyperglycemia in patients with insulinoma, but the effect of insulinoma on normal ß-cells has not been investigated. We examined the glucose transporter 2 (GLUT2) and glucagon-like peptide 1 receptor (GLP1R) expression in normal pancreatic ß-cells of five patients with insulinoma and five patients with normal glucose tolerance (NGT) as controls. The positive rate of GLUT2-or GLP1R-positive islets in the nontumor area was calculated by the ratio with the analyzed islets. For functional in vitro analyses, q-PCR and Western blotting were performed after insulin loading on MIN6 cells. The expression rates of both GLUT2 and GLP1R were significantly lower in nontumor area islets of insulinoma patients than in patients with NGT (GLUT2: 31.6 ± 15.3% vs 95.9 ± 6.7%, p < 0.01, GLP1R: 66.8 ± 15.0% vs 96.7 ± 5.0%, p < 0.01). Exposure of MIN6 cells to high concentrations of insulin resulted in a significant decrease in GLUT2 protein for 12 h and GLP1R protein for 24 h (GLUT2; 1.00 ± 0.079 vs 0.81 ± 0.04. p = 0.02, GLP1R; 1.00 ± 0.10 vs 0.50 ± 0.24, p = 0.03) but not in those mRNAs. Our findings show that insulinoma is associated with the downregulation of GLUT2 and GLP1R expression in nontumor area islets. These phenomena may be caused by high levels of insulin.

Multicenter prospective trial of total gastrectomy versus proximal gastrectomy for upper third cT1 gastric cancer.

BACKGROUND: The appropriate surgical procedure for patients with upper third early gastric cancer is controversial. We compared total gastrectomy (TG) with proximal gastrectomy (PG) in this patient population. METHODS: A multicenter, non-randomized trial was conducted, with patients treated with PG or TG. We compared short- and long-term outcomes between these procedures. RESULTS: Between 2009 and 2014, we enrolled 254 patients from 22 institutions; data from 252 were included in the analysis. These 252 patients were assigned to either the PG (n = 159) or TG (n = 93) group. Percentage of body weight loss (%BWL) at 1 year after surgery, i.e., the primary endpoint, in the PG group was significantly less than that of the TG group (- 12.8% versus - 16.9%; p = 0.0001). For short-term outcomes, operation time was significantly shorter for PG than TG (252 min versus 303 min; p < 0.0001), but there were no group-dependent differences in blood loss and postoperative complications. For long-term outcomes, incidence of reflux esophagitis in the PG group was significantly higher than that of the TG group (14.5% versus 5.4%; p = 0.02), while there were no differences in the incidence of anastomotic stenosis between the two (5.7% versus 5.4%; p = 0.92). Overall patient survival rates were similar between the two groups (3-year survival rates: 96% versus 92% in the PG and TG groups, respectively; p = 0.49). CONCLUSIONS: Patients who underwent PG were better able to control weight loss without worsening the prognosis, relative to those in the TG group. Optimization of a reconstruction method to reduce reflux in PG patients will be important.

Liver resection with thrombectomy for patients with hepatocellular carcinoma and tumour thrombus in the inferior vena cava or right atrium.

BACKGROUND: Hepatocellular carcinoma (HCC) with tumour thrombus (TT) in the inferior vena cava (IVC) or right atrium (RA) is a rare advanced disease state with a poor prognosis. The aim of this study was to examine survival after surgical resection. METHODS: Patients with HCC and TT of either the IVC or RA, who underwent liver resection between February 1997 and July 2017, were included. Their short- and long-term outcomes and surgical details were analysed retrospectively. RESULTS: Thirty-seven patients were included; 16 patients had TT in the IVC below the diaphragm, eight had TT in the IVC above the diaphragm, and 13 had TT entering the RA. Twelve patients had advanced portal vein TT (portal vein invasion (Vp) greater than Vp3 and Vp4), ten had bilobar disease, and 12 had extrahepatic disease. There were no in-hospital deaths, although two patients died within 90 days. Median survival did not differ between patients who had resection with curative intent (18·7 months) and those with residual tumour in the lung only (20·7 months), but survival was poor for patients with residual tumour in the liver (8·3 months). CONCLUSION: Liver resection with thrombectomy for advanced HCC with TT in the IVC or RA is safe and feasible, leading to moderate survival.

ANTECEDENTES: El carcinoma hepatocelular con trombo tumoral (TT) en la vena cava inferior (inferior vena cava, IVC) o en la aurícula derecha (right atrium, RA) es un estado avanzado de la enfermedad raro, con un pronóstico desfavorable. En este estudio analizamos la supervivencia después de la resección quirúrgica. MÉTODOS: Se incluyeron pacientes con carcinoma hepatocelular con TT en la IVC o en la RA, que se sometieron a resección hepática entre febrero de 1997 y julio de 2017. Los resultados a corto y a largo plazo de estos pacientes y los detalles quirúrgicos se analizaron retrospectivamente. RESULTADOS: Se incluyeron 37 pacientes. Entre estos pacientes, se identificaron 16 pacientes con TT en la IVC infradiafragmática, 8 pacientes con TT en la IVC supradiafragmática y 13 pacientes con TT entrando en la AR. Doce pacientes asociaron TT avanzado en la vena porta más allá de vp 3 y 4, 10 pacientes tenían enfermedad bilobar y 12 pacientes tenían enfermedad extrahepática. A pesar de que la tasa de mortalidad hospitalaria fue cero, dos pacientes fallecieron a los 90 días. Aunque la mediana del tiempo de supervivencia no fue diferente entre el grupo al que se le realizó resección con intención curativa (18,7 meses) y aquellos con tumor residual solo en el pulmón (20,7 meses), la supervivencia fue extremadamente pobre para los pacientes con tumor residual en el hígado (8,3 meses). CONCLUSIÓN: La resección hepática con trombectomía para el carcinoma hepatocelular avanzado con trombo tumoral en la vena cava inferior o en la aurícula derecha es segura y factible, asociándose a una supervivencia moderada.

Studies of Pig Complement: Measurement of Pig CH50, ACH50, and Components.

BACKGROUND: On the basis of a comparison of the hemolytic complement titer in pigs with that in humans, the complement system of pigs was investigated. The response of innate immunity, such as the natural antibodies, against humans was also examined. METHODS: Hemolytic complement activity of pig serum was measured with the use of a microtitration technique. CH50 was determined according to the method of Mayer. ACH50 was assayed according to the methods of Platts-Milles and Ishizaka. Hemolytic activities of C1, C4, C2, C3, C5, C8, and C9 were estimated through the use of intermediate cells and reagents, as described previously. In addition, the pig natural anti-human antibody was studied with the use of human peripheral blood mononuclear cells (PBMCs). Human PBMCs were stained with 5% pig serum, followed by staining with fluorescein isothiocyanate-labeled goat anti-pig IgG and IgM. The resulting stained cells were quantified by use of a FACScalibur system. The alternative pathway of pig complement was also measured with the use of human erythrocytes and normal pooled pig serum with or without Mg(++)EGTA. RESULTS: Both the CH50 and ACH50 titers were lower than those of humans. Concerning the components, except for C3, each component, that is, C1, C4, C2, C5, C8, and C9, was also lower than that of humans, based on measured values for human complement components. Pig serum clearly contains natural antibodies, IgG and IgM, to human PBMCs. The alternative pathway of pig complement reacted with human erythrocytes. CONCLUSIONS: As a whole, pig innate immunity, the complement system and natural antibody, recognizes the surfaces of human cells.

HLA-G1, but Not HLA-G3, Suppresses Human Monocyte/Macrophage-mediated Swine Endothelial Cell Lysis.

The inhibitory function of HLA-G1, a class Ib molecule, on monocyte/macrophage-mediated cytotoxicity was examined. The expression of inhibitory receptors that interact with HLA-G, immunoglobulin-like transcript 2 (ILT2), ILT4, and KIR2DL4 (CD158d) on in vitro-generated macrophages obtained from peripheral blood mononuclear cells and the phorbol 12-myristate 13-acetate (PMA)-activated THP-1 cells were examined by flow cytometry. cDNAs of HLA-G1, HLA-G3, HLA-E, and human ß2-microglobulin were prepared, transfected into pig endothelial cells (PECs), and macrophage- and the THP-1 cell-mediated PEC cytolysis was then assessed. In vitro-generated macrophages expressed not only ILT2 and ILT4 but CD158d as well. The transgenic HLA-G1 on PEC indicated a significant suppression in macrophage-mediated cytotoxicity, which was equivalent to that of transgenic HLA-E. HLA-G1 was clearly expressed on the cell surface of PEC, whereas the levels of HLA-G3 were much lower and remained in the intracellular space. On the other hand, the PMA-activated THP-1 cell was less expressed these inhibitory molecules than in vitro-generated macrophages. Therefore, the HLA-G1 on PECs showed a significant but relatively smaller suppression to THP-1 cell-mediated cytotoxicity compared to in vitro-generated macrophages. These results indicate that by generating HLA-G1, but not HLA-G3, transgenic pigs can protect porcine grafts from monocyte/macrophage-mediated cytotoxicity.

Human HLA-Ev (147) Expression in Transgenic Animals.

BACKGROUND: In our previous study, we reported on the development of substituting S147C for HLA-E as a useful gene tool for xenotransplantation. In this study we exchanged the codon of HLA-Ev (147), checked its function, and established a line of transgenic mice. METHODS: A new construct, a codon exchanging human HLA-Ev (147) + IRES + human beta 2-microgloblin, was established. The construct was subcloned into pCXN2 (the chick beta-actin promoter and cytomegalovirus enhancer) vector. Natural killer cell- and macrophage-mediated cytotoxicities were performed using the established the pig endothelial cell (PEC) line with the new gene. Transgenic mice with it were next produced using a micro-injection method. RESULTS: The expression of the molecule on PECs was confirmed by the transfection of the plasmid. The established molecules on PECs functioned well in regulating natural killer cell-mediated cytotoxicity and macrophage-mediated cytotoxicity. We have also successfully generated several lines of transgenic mice with this plasmid. The expression of HLA-Ev (147) in each mouse organ was confirmed by assessing the mRNA. The chick beta-actin promoter and cytomegalovirus enhancer resulted in a relatively broad expression of the gene in each organ, and a strong expression in the cases of the heart and lung. CONCLUSION: A synthetic HLA-Ev (147) gene with a codon usage optimized to a mammalian system represents a critical factor in the development of transgenic animals for xenotransplantation.

Exosomal microRNA in serum is a novel biomarker of recurrence in human colorectal cancer.

BACKGROUND: Functional microRNAs (miRNAs) in exosomes have been recognised as potential stable biomarkers in cancers. The aim of this study is to identify specific miRNAs in exosome as serum biomarkers for the early detection of recurrence in human colorectal cancer (CRC). METHODS: Serum samples were sequentially obtained from six patients with and without recurrent CRC. The miRNAs were purified from exosomes, and miRNA microarray analysis was performed. The miRNA expression profiles and copy number aberrations were explored using microarray and array CGH analyses in 124 CRC tissues. Then, we validated exosomal miRNAs in 2 serum sample sets (90 and 209 CRC patients) by quantitative real-time RT-PCR. RESULTS: Exosomal miR-17-92a cluster expression level in serum was correlated with the recurrence of CRC. Exosomal miR-19a expression levels in serum were significantly increased in patients with CRC as compared with healthy individuals with gene amplification. The CRC patients with high exosomal miR-19a expression showed poorer prognoses than the low expression group (P<0.001). CONCLUSIONS: Abundant expression of exosomal miR-19a in serum was identified as a prognostic biomarker for recurrence in CRC patients.

De novo malignancy after pancreas transplantation in Japan.

BACKGROUND: Long-term immunosuppression is associated with an increased risk of cancer. Especially, the immunosuppression in pancreas transplantation is more intensive than that in other organ transplantation because of its strong immunogenicity. Therefore, it suggests that the risk of post-transplant de novo malignancy might increase in pancreas transplantation. However, there have been few studies of de novo malignancy after pancreas transplantation. The aim of this study was to analyze the incidence of de novo malignancy after pancreas transplantation in Japan. METHODS: Post-transplant patients with de novo malignancy were surveyed and characterized in Japan. RESULTS: Among 107 cases receiving pancreas transplantation in Japan between 2001 and 2010, de novo malignancy developed in 9 cases (8.4%): post-transplant lymphoproliferative disorders in 6 cases, colon cancer in 1 case, renal cancer in 1 case, and brain tumor in 1 case. CONCLUSIONS: We clarified the incidence of de novo malignancy after pancreas transplantation in Japan.

Identification of a bona fide microRNA biomarker in serum exosomes that predicts hepatocellular carcinoma recurrence after liver transplantation.

BACKGROUND: Predictive biomarkers for the recurrence of hepatocellular carcinoma (HCC) have great benefit in the selection of treatment options, including liver transplantation (LT), for HCC. The purpose of this study was to identify specific microRNAs (miRs) in exosomes from the serum of patients with recurrent HCC and to validate these molecules as novel biomarkers for HCC recurrence. METHODS: We employed microarray-based expression profiling of miRs derived from exosomes in the serum of HCC patients to identify a biomarker that distinguishes between patients with and without HCC recurrence after LT. This was followed by the validation in a separate cohort of 59 HCC patients who underwent living related LT. The functions and potential gene targets of the recurrence-specific miRs were analysed using a database, clinical samples and HCC cell lines. RESULTS: We found that miR-718 showed significantly different expression in the serum exosomes of HCC cases with recurrence after LT compared with those without recurrence. Decreased expression of miR-718 was associated with HCC tumour aggressiveness in the validated cohort series. We identified HOXB8 as a potential target gene of miR-718, and its upregulation was associated with poor prognosis. CONCLUSION: Circulating miRs in serum exosomes have potential as novel biomarkers for predicting HCC recurrence.

MicroRNA-1246 expression associated with CCNG2-mediated chemoresistance and stemness in pancreatic cancer.

BACKGROUND: Pancreatic cancer has a poor prognosis because of its high refractoriness to chemotherapy and tumour recurrence, and these properties have been attributed to cancer stem cells (CSCs). MicroRNA (miRNA) regulates various molecular mechanisms of cancer progression associated with CSCs. This study aimed to identify the candidate miRNA and to characterise the clinical significance. METHODS: We established gemcitabine-resistant Panc1 cells, and induced CSC-like properties through sphere formation. Candidate miRNAs were selected through microarray analysis. The overexpression and knockdown experiments were performed by evaluating the in vitro cell growth and in vivo tumourigenicity. The expression was studied in 24 pancreatic cancer samples after laser captured microdissection and by immunohistochemical staining. RESULTS: The in vitro drug sensitivity of pancreatic cancer cells was altered according to the miR-1246 expression via CCNG2. In vivo, we found that miR-1246 could increase tumour-initiating potential and induced drug resistance. A high expression level of miR-1246 was correlated with a worse prognosis and CCNG2 expression was significantly lower in those patients. CONCLUSIONS: miR-1246 expression was associated with chemoresistance and CSC-like properties via CCNG2, and could predict worse prognosis in pancreatic cancer patients.

Monocytic suppressor cells derived from peripheral blood suppress xenogenic natural killer cell lysis.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) were initially found to contribute to immunosuppression in tumor patients and have recently been recognized as a subset of innate immune cells that are capable of regulating adaptive immunity. A variety of innate immune stimuli, such as lipopolysaccharide, act as a double-edged sword, inducing both the maturation of dendritic cells and the expansion of MDSCs. METHODS: We isolated MDSCs from peripheral blood mononuclear cells (PBMCs) and examined the suppressive effect of MDSCs against xenocytotoxicity mediated by YT cells, a natural killer-like cell line, with the use of the lactate dehydrogenase assay method. RESULTS: Although primed MDSCs induced no significant suppression in YT cell-mediated cytotoxicity, activated MDSCs significantly suppressed the xenogenic cytotoxicity. CONCLUSIONS: These findings indicate that MDSCs have a great deal of potential as a therapeutic strategy for dealing with xenograft rejection. Further investigations of the underlying mechanisms will facilitate the development of this therapeutic strategy.

Regulation of macrophage-mediated xenocytotoxicity by overexpression of alpha-2,6-sialyltransferase in swine endothelial cells.

Macrophages play an important role in xenogenic rejection and therefore may represent a major obstacle in clinical application of xenograft. CD33-related sialic acid-binding immunoglobulin-like lectins (Siglecs) belong to the immunoglobulin superfamily and contain a cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM) that is able to inhibit cytokine production. Because human macrophages express various CD33-related Siglecs, we hypothesized that overexpression of α-2,6-sialyltransferase (2,6-ST) in swine endothelial cells (SECs) might prevent the cytotoxicity mediated by macrophages. To confirm our hypothesis, the cytotoxicity of macrophages against 2,6-ST-overexpressing SECs was determined with the use of in vitro-generated macrophages as an effector and naïve or 2,6-ST-overexpressing SECs as a target. The 2,6-ST-overexpressing SECs were established by transfection with the genes for 2,6-ST. Transfection of 2,6-ST led to significant reduction in cytotoxicity compared with naïve SECs. These findings indicate that the sialylated ligands against CD33-related Siglecs may provide an effective therapeutic strategy to inhibit macrophage-mediated xenograft rejection in xenotransplantation.

Amplification of PVT-1 is involved in poor prognosis via apoptosis inhibition in colorectal cancers.

BACKGROUND: We previously conducted gene expression microarray analyses to identify novel indicators for colorectal cancer (CRC) metastasis and prognosis from which we identified PVT-1 as a candidate gene. PVT-1, which encodes a long noncoding RNA, mapped to chromosome 8q24 whose copy-number amplification is one of the most frequent events in a wide variety of malignant diseases. However, PVT-1 molecular mechanism of action remains unclear. METHODS: We conducted cell proliferation and invasion assays using colorectal cancer cell lines transfected with PVT-1siRNA or negative control siRNA. Gene expression microarray analyses on these cell lines were also carried out to investigate the molecular function of PVT-1. Further, we investigated the impact of PVT-1 expression on the prognosis of 164 colorectal cancer patients by qRT-PCR. RESULTS: CRC cells transfected with PVT-1 siRNA exhibited significant loss of their proliferation and invasion capabilities. In these cells, the TGF-ß signalling pathway and apoptotic signals were significantly activated. In addition, univariate and multivariate analysis revealed that PVT-1 expression level was an independent risk factor for overall survival of colorectal cancer patients. CONCLUSION: PVT-1, which maps to 8q24, generates antiapoptotic activity in CRC, and abnormal expression of PVT-1 was a prognostic indicator for CRC patients.

PICT1 regulates TP53 via RPL11 and is involved in gastric cancer progression.

BACKGROUND: The TP53 pathway is frequently inactivated in human cancers. PICT1 (also known as GLTSCR2) is a novel regulator of the MDM2-TP53 pathway via its interaction with the ribosomal protein RPL11 in the nucleolus. However, the clinical significance of PICT1 in gastric cancer remains unknown. METHODS: To evaluate PICT1 function, we used shRNA to inhibit PICT1 expression in gastric cancer cells that expressed wild-type TP53. PICT1 expression and TP53 mutation status were quantified in 110 cases of primary gastric cancer to explore the impact of PICT1 expression levels on gastric cancer. RESULTS: Deficiency of PICT1 significantly impaired cell proliferation and colony formation via TP53-mediated cell cycle arrest. Following induction of PICT1 deficiency, RPL11 translocated out of the nucleolus. Of the 110 gastric cancer samples tested, 70 (63.6%) and 40 (36.4%) tumours expressed wild-type and mutant TP53, respectively. In gastric cancer patients with wild-type TP53 tumours, patients with relatively low PICT1 expression levels had a better prognosis compared with high expression level patients (P=0.046). CONCLUSION: The findings suggest that PICT1 has a crucial role in gastric cancer progression by regulating the MDM2-TP53 pathway through RPL11. Clinically, PICT1 expression is a novel prognostic parameter in gastric cancer patients with wild-type TP53 tumours.

miR-320c regulates gemcitabine-resistance in pancreatic cancer via SMARCC1.

BACKGROUND: Gemcitabine-based chemotherapy is the standard treatment for pancreatic cancer. However, the issue of resistance remains unresolved. The aim of this study was to identify microRNAs (miRNAs) that govern the resistance to gemcitabine in pancreatic cancer. METHODS: miRNA microarray analysis using gemcitabine-resistant clones of MiaPaCa2 (MiaPaCa2-RGs), PSN1 (PSN1-RGs), and their parental cells (MiaPaCa2-P, PSN1-P) was conducted. Changes in the anti-cancer effects of gemcitabine were studied after gain/loss-of-function analysis of the candidate miRNA. Further assessment of the putative target gene was performed in vitro and in 66 pancreatic cancer clinical samples. RESULTS: miR-320c expression was significantly higher in MiaPaCa2-RGs and PSN1-RGs than in their parental cells. miR-320c induced resistance to gemcitabine in MiaPaCa2. Further experiments showed that miR-320c-related resistance to gemcitabine was mediated through SMARCC1, a core subunit of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex. In addition, clinical examination revealed that only SMARCC1-positive patients benefited from gemcitabine therapy with regard to survival after recurrence (P=0.0463). CONCLUSION: The results indicate that miR-320c regulates the resistance of pancreatic cancer cells to gemcitabine through SMARCC1, suggesting that miR-320c/SMARCC1 could be suitable for prediction of the clinical response and potential therapeutic target in pancreatic cancer patients on gemcitabine-based therapy.

Paired related homoeobox 1, a new EMT inducer, is involved in metastasis and poor prognosis in colorectal cancer.

BACKGROUND: Paired related homoeobox 1 (PRRX1) has been identified as a new epithelial-mesenchymal transition (EMT) inducer in breast cancer. However, the function of PRRX1 in colorectal cancer (CRC) has not been elucidated. METHODS: We utilised ectopic PRRX1-expressing cell lines to analyse the function of PRRX1 in CRC. The clinical significance of PRRX1 was also examined on three independent CRC case sets. RESULTS: PRRX1 induced EMT and the stem-like phenotype in CRC cells. In contrast to studies of breast cancer, abundant expression of PRRX1 was significantly associated with metastasis and poor prognosis in CRC. CONCLUSION: PRRX1 is an indicator of metastasis and poor prognosis in CRC cases. Further investigation is required to uncover the signalling network regulating PRRX1.

Ep-CAM is a significant prognostic factor in pancreatic cancer patients by suppressing cell activity.

The identification of molecular markers useful for predicting prognosis in pancreatic cancer patients is crucial for advances in disease management. The epithelial cell adhesion molecule (Ep-CAM) is known to express in most epithelial malignancies and was reported as a tumor marker or a candidate of molecular targeting therapy. However, the clinical significance of Ep-CAM expression in pancreatic cancer is not well-known. We determined the difference of malignant potential between parental and Ep-CAM-transfected pancreatic cancer cell lines by using proliferation, invasion and migration assay. Furthermore, we determined the relationship between tumoral Ep-CAM expression of resected specimens and clinical prognosis in 95 pancreatic cancer patients receiving radical surgery at two different cancer centers. One of the three Ep-CAM-transfected cell lines showed significantly low proliferation rate compared with the parental cell, while there was no difference in the other two cell lines. In invasion and migration assays, Ep-CAM-transfected cells showed significantly lower malignant potential than parental in all of the three cell lines. In 95 pancreatic cancer patients, 47 patients showed high-Ep-CAM expression, while 48 patients showed low, and there was no difference of clinicopathological features between Ep-CAM high and low-expression group. High-Ep-CAM expression group showed significantly good prognosis in overall survival (3-year survival; 56.2 versus 19.2%, P=0.0018) as well as in disease-free survival (3-year survival; 40.3 versus 14.4%, P=0.038) compared with low-expression group. In addition, the impact of Ep-CAM was observed strongly in LN-negative group when the influence of Ep-CAM was examined with dividing patients into LN-positive and negative group. In multivariate analysis, Ep-CAM expression was one of the independent prognostic factors as well as histology and lymph node metastasis. Ep-CAM expression was found to be related to the suppression of pancreatic cancer cell activity and the good prognosis in pancreatic cancer patients receiving the curative resection.