ß-Catenin-activated inflammatory hepatocellular adenoma with pigmentation and atypical features: a case report.

Hepatocellular adenomas are rare diseases, defined as benign liver neoplasms composed of cells with hepatocellular differentiation. Differential diagnosis of hepatocellular adenoma from other lesions, including focal nodular hyperplasia and hepatocellular carcinoma, is crucial to determine treatment strategy. We describe a case of ß-catenin-activated inflammatory hepatocellular adenoma with malignant transformation. A 50-year-old man with a suspected liver tumor, based on abdominal ultrasonography findings, was referred to our hospital. Contrast-enhanced computed tomography and magnetic resonance imaging revealed a liver tumor in S2 which was enhanced in the arterial phase to the delayed phase. Based on diagnostic imaging findings, hepatocellular adenoma or focal nodular hyperplasia was suspected. We considered the possibility of malignant potential because of the enlargement of the lesion. Thus, we performed a laparoscopic hepatectomy. Histological examination showed pigment deposition in the hepatocytes, which was determined to be lipofuscin. Mild nuclear swelling and atypia in the tumor area indicated nodular growth. Based on the histological and immunohistochemical findings, the diagnosis was ꞵ-catenin-activated inflammatory hepatocellular adenoma with atypical features. The imaging features of hepatocellular adenoma and focal nodular hyperplasia are similar, but if the tumor tends to grow, surgical treatment should be performed because of the possibility of malignant hepatocellular adenoma.

Conversion surgery following gemcitabine plus cisplatin therapy for initially unresectable gallbladder cancer with peritoneal carcinomatosis: a case report.

BACKGROUND: Conversion surgery, which is defined as chemotherapy or chemoradiotherapy followed by radical surgery, may improve survival of patients with initially unresectable advanced biliary tract cancer, including gallbladder cancer. However, there are few reports on conversion surgery for advanced gallbladder cancer. CASE PRESENTATION: A 69-year-old woman was referred to our hospital with initially unresectable gallbladder cancer with peritoneal carcinomatosis. She underwent gemcitabine plus cisplatin therapy for 9 months. Extended cholecystectomy, resection of the extrahepatic bile duct with regional lymph node dissection, and total omentectomy were then performed as conversion surgery. The patient has survived without recurrence for 19 months postoperatively (31 months after the initial diagnosis) while continuing chemotherapy. CONCLUSIONS: This case suggests that conversion surgery for advanced gallbladder cancer is effective and may be curative for locally advanced disease and distant metastasis such as peritoneal carcinomatosis.

[A Case of Locally Advanced Pancreatic Cancer Successfully Resected after S-1 Therapy in an Elderly Patient].

We report a case of locally advanced pancreatic body cancer, accomplishing R0 resection following preoperative chemotherapy. An 80-year-old female patient was admitted to our hospital because of high CA19-9 levels.Based on computed tomography images, she was diagnosed with locally advanced cancer of the pancreatic body.We started S-1 chemotherapy (100mg/day, 2 weeks administration 1 week rest)because the tumor was suspected to have invaded the celiac trunk and the common hepatic artery.The tumor decreased in size, and the encasement of the celiac trunk and the common hepatic artery were released, following 6 months of chemotherapy.Subsequently, distal pancreatectomy with D2 lymph node dissection was performed.The patient was healthy and showed no signs of recurrence 5 years and 9 months after surgery.

Vimentin-positive gastric adenocarcinoma arising in a hyperplastic polyp.

We report a case of vimentin-positive early gastric adenocarcinoma arising in a hyperplastic polyp (HP). A 72-year-old Japanese man was admitted for the detailed examination of a gastric polyp. He had a subtotal gastrectomy due to acute abdomen 12 years ago. Upper endoscopy revealed a pedunculated polyp measuring approximately 2 cm on the greater curvature of upper body of the remnant stomach. Magnifying endoscopy revealed that the microsurface pattern was irregular and partially absent accompanied with irregular microvessels at the upper end of the polyp. We speculated that the lesion was an adenocarcinoma arising in the HP. Endoscopic submucosal dissection (ESD) was performed. Histological examination of the ESD specimen revealed that the lesion consisted of well- to poorly differentiated adenocarcinoma at the protruding lesion and foveolar hyperplastic epithelia at the base of the polyp. Immunohistochemically, most of tumor cells that comprised poorly-differentiated adenocarcinoma were positive for both cytokeratin and vimentin. Although carcinomas have occasionally been found in HPs, the histological features of the present case are considered extremely unusual. To the best of our knowledge, this is the first case of vimentin-positive early gastric carcinoma arising in a HP.

Total Calcium and Albumin Are Decreased in the Deeper Epidermis of Patients with Chronic Kidney Disease-Associated Pruritus.

BACKGROUND/AIMS: In our earlier studies, we reported high concentrations of intra- and extracellular calcium ions (Ca2+) in the deeper epidermis of patients with chronic kidney disease (CKD) and associated pruritus. To determine the cause of this phenomenon, we measured total calcium (TCa) concentrations in the deeper epidermis and performed immunostaining of epidermal albumin, which binds to Ca2+. METHODS: This study included 45 patients with CKD-stage 5, which was defined as severely reduced kidney function (i.e., estimated glomerular filtration rate less than 15 mL/min or on dialysis). Subjects were divided into the pruritus group, consisting of patients with mild, moderate, or severe uremic pruritus, and the non-pruritus group, consisting of patients with no or slight pruritus. The particle-induced X-ray emission method was used to measure elements including TCa. Furthermore, we have immunostained epidermal albumin using anti-albumin antibodies and compared the results in the pruritus and non-pruritus groups. RESULTS: The TCa concentration in the spinous layer of patients with CKD with CKD-associated pruritus was lower than in patients with CKD without pruritus (median [range], 395 [235-1,063] vs. 476 [342-1,243] µg/g). The intensity of epidermal albumin expression in the spinous layer was weaker in patients with CKD with CKD-associated pruritus than in those without. CONCLUSION: Patients with CKD with CKD-associated pruritus demonstrated higher Ca2+ concentrations but lower TCa concentrations than patients without CKD-associated pruritus. This could be in part due to low concentrations of epidermal albumin, which binds to Ca2+, in those with CKD-associated pruritus. These results clarify the pathophysiology of CKD-associated pruritus, providing a valuable foundation for the future development of treatments for this condition.

DICER1 hotspot mutations in ovarian Sertoli-Leydig cell tumors: a potential association with androgenic effects.

Sertoli-Leydig cell tumors (SLCTs) are representative of androgenic ovarian tumors, and they show diverse histologic differentiation, including heterologous differentiation. Genetically, SLCTs are characterized by the presence of DICER1 mutations. In the present study, we analyzed the correlation between somatic DICER1 hotspot mutations and clinicopathological features in 10 ovarian SLCTs. Six of the 10 (60%) SLCTs harbored a DICER1 hotspot mutation. Five of the 6 DICER1-mutated SLCT patients showed androgenic manifestations, including amenorrhea and hirsutism, and 4 of the 6 were associated with the significant elevation of serum testosterone. In contrast, none of the 4 DICER1 wild-type SLCT patients showed virilization. The patient age at diagnosis was lower in those with DICER1-mutated SLCTs (average, 24.7; range, 17-43) than in those with DICER1 wild-type tumors (average, 64.8; range, 47-77). Histologically, heterologous differentiation was found in 4 SLCTs, all of which were DICER1 mutant. Heterologous components included gastrointestinal-type mucinous epithelium (n=3), carcinoid (n=1), and rhabdomyosarcoma (n=1). In the latter, the rhabdomyosarcomatous component was dominant to the SLCT component. In summary, DICER1 hotspot mutations are closely associated with androgenic effects in ovarian SLCTs. It is suggested that DICER1 mutations are involved in the dysregulation of sex hormone synthesis in SLCT patients. Somatic DICER1 hotspot mutations are more common in SLCT patients during the reproductive years than in those during the postreproductive years. DICER1 hotspot mutations may support the pathological diagnosis of SLCTs in cases wherein the heterologous component overwhelms and masks the SLCT component.

Adenomyoepithelioma with carcinoma of the breast: A report of two cases and a review of the literature.

We herein described two cases of adenomyoepithelioma (AME) with carcinoma of the breast. Both of them were Japanese women, and they presented with a mass in their breast. Post-operative specimens revealed encapsulated and well-circumscribed tumors with local invasion, necrosis, cytological atypia, and a high mitotic rate. In immunohistochemistry, coincidentally with the loose adhesion pattern of myoepithelial cells in both cases, the intensities of E-cadherin and beta-catenin were much weaker in myoepithelial than luminal epithelial cells, with almost negative finding of beta-catenin in one case. We first found deletion of CDH1 and polysomy of CEP16 in myoepithelial cells by double color-fluorescence in situ hybridization. The two cases have been followed up for 5-8 years, and both remained free from local recurrence and distant metastases. We also presented an overview of 47 cases of AME with carcinoma in English-language literatures.

[A case of angiosarcoma of the spleen with intraperitoneal bleeding].

A 56-year-old man was admitted to our hospital with a history of abdominal discomfort and loss of appetite. Six days later, he suddenly went into shock; despite repeated blood transfusions, he died. Autopsy revealed the cause of death to be a ruptured splenic angiosarcoma, which had metastasized to multiple sites in the liver and bone. Splenic angiosarcoma is rare, and its pathophysiology is unclear. When presented with splenic angiosarcoma or suggestive symptoms, including splenic bleeding, splenomegaly, abdominal discomfort, and abdominal pain, we should carefully monitor the patient for signs of coagulopathy and prepare for the possibility of rapid progression to disseminated intravascular coagulation. In general, patients with angiosarcoma have a poor prognosis. Therefore, we hope this report will help in improving the prognosis of patients suffering from angiosarcoma by contributing to the limited clinical experience.

Periodic knee injections of collagen tripeptide delay cartilage degeneration in rabbit experimental osteoarthritis.

INTRODUCTION: Collagen peptides have been reported to possess various biological activities for various cell types. The purposes of this study were, first, to examine the therapeutic effects of collagen tripeptide (Ctp) in rabbit osteoarthritis and, second, to explore a synergetic effect with hyaluronan (HA). METHODS: Osteoarthritis was induced by anterior cruciate ligament transection of the right knee in 72 Japanese white rabbits and they were divided into four groups (control, Ctp, HA and Ctp/HA). Each material was injected weekly into the knee, and knee joint samples were collected 5, 10 and 15 weeks after surgery. Macroscopic and histomorphological analyses of cartilage were conducted. Expression of type II collagen and matrix metalloproteinase-13 was also analyzed immunohistochemically. A Tukey's honestly significant difference test was used to evaluate the statistical significance of difference in the macroscopic, histological and immnohistochemical results. RESULTS: All treatment groups exhibited slightly higher resistance to the progression of osteoarthritis than the control group macroscopically 15 weeks after surgery. Histologically, intra-articular injection of Ctp significantly reduced cartilage degradation 10 weeks after surgery, and Ctp/HA significantly reduced it 5 weeks after surgery in comparison with the control. Immunohistochemically, both Ctp-treated and Ctp/HA-treated groups had significantly increased type II collagen-positive chondrocytes at the fifth week after the surgery, although the numbers of matrix metalloproteinase-13-positive chondrocytes were not affected. CONCLUSION: Periodical injections of Ctp and Ctp/HA delayed progression of cartilage degeneration of early osteoarthritis induced by anterior cruciate ligament transection in rabbits. This effect appears to be exerted by promotion of type II collagen synthesis predominantly.

p63 as a prognostic marker for giant cell tumor of bone.

BACKGROUND AND PURPOSE: Giant cell tumor of bone (GCT) is sometimes difficult to distinguish from other giant-cell-rich tumors such as chondroblastoma (CHB) and aneurysmal bone cyst (ABC). The usefulness of p63 as a diagnostic marker for GCT is controversial. While there have been no reports about p63 as a prognostic marker for local recurrence, various p63-positive rates in GCT have been reported. The purpose of this study was to investigate retrospectively whether p63 is useful as a diagnostic marker and/or a prognostic marker for local recurrence of GCT. METHODS: This study included 36 patients diagnosed with either GCT (n = 16), CHB (n = 9), ABC (n = 7), or non-ossifying fibroma (NOF) (n = 4). p63 immunostaining was performed for all specimens. The mean p63-positive rate was compared with the four diseases and between the recurrent and non-recurrent cases of GCT. RESULTS: Although the mean p63-positive rate for GCT (36.3%) was statistically higher than that of all other diseases examined (CHB: 15.2%; ABC: 5.8%; NOF: 3.4%), p63 was not specific for GCT. The mean p63-positive rate for recurrent GCT cases (73.6%) was statistically higher than that for non-recurrent cases (29.1%). CONCLUSION: In the diagnosis of GCT, p63 is a useful but not a conclusive marker. However, p63 did appear to indicate the biological aggressiveness of GCT. Therefore, p63 may help surgeons to estimate the risk of recurrence after surgery and help them to choose the best treatment for each GCT case.

Potential of exogenous cartilage proteoglycan as a new material for cartilage regeneration.

BACKGROUND: Although proteoglycan (PG) is one of the major components of cartilage matrices, its biological function is not fully elucidated. METHODS: The objectives of this study were to investigate the proliferation and differentiation of chondrocytes embedded in atelocollagen gel with exogenous cartilage PG (PG-atelocollagen gel) in vitro, and also to evaluate the repair of cartilage defects by PG-atelocollagen gel in vivo. In the in vitro study, rabbit chondrocytes were cultured in the PG-atelocollagen gel. Cell proliferation and mRNA expression levels were measured, and gels were histologically evaluated. In the in vivo study, cultured PG-atelocollagen gel containing chondrocytes were transplanted into full-thickness articular cartilage defects in rabbit knees, and evaluated macroscopically and histologically. RESULTS: For the in vitro study, chondrocyte proliferation in 5.0 mg/ml PG-atelocollagen gel was enhanced, and the gene expression of Col2a1 and Aggrecan were decreased. In contrast, chondrocyte proliferation in 0.1 and 1.0 mg/ml PG-atelocollagen gel was not enhanced. The gene expression of Aggrecan in 0.1 and 1.0 mg/ml PG-atelocollagen gel was increased. For the in vivo study, the histological average total score of the 0.1 mg/ml PG-atelocollagen gel was significantly better than that of the group without PG. CONCLUSIONS: Although the appropriate concentration of PG has not been defined, this study suggests the efficacy of PG for cartilage repair.

The actual tendon-bone interface strength in a rabbit model.

PURPOSE: The purpose of this study was to evaluate the strength of the interface throughout the entire integration process by use of tendon graft reinforced with a suture material compared with nonreinforced tendon graft. METHODS: Using 60 skeletally mature female Japanese white rabbits, we performed biomechanical testing and histologic evaluation to compare tendon grafts reinforced with a suture material (suture group) and nonreinforced grafts (control group). The tendon graft was drawn through a bone tunnel measuring 2.5 mm in diameter and was tightly fixed. For biomechanical testing, the tendon graft was tested in tensile loading along the axis of the bone tunnel at a crosshead speed of 100 mm/min. RESULTS: On biomechanical testing, at 4, 6, 8, and 12 weeks, tendon grafts had pulled out of the bone tunnel in the suture group. In the control group all tendon grafts had pulled out at 4 and 6 weeks, and rupture at the midsubstance was seen at 8 and 12 weeks. The failure load-to-tunnel length ratio was significantly larger in the suture group compared with the control group at 8 and 12 weeks. On histologic evaluation, both groups had similar findings with direct attachments to bone by 12 weeks. CONCLUSIONS: In this study of the healing characteristics of augmented and nonaugmented tendon grafts placed in a bone tunnel, we found that the suture-augmented tendons had superior failure load-to-tunnel length ratios at 8, 12, and 16 weeks compared with nonaugmented tendons. The failure mode in the augmented grafts was tendon pullout at all time points except 16 weeks, whereas the nonaugmented grafts failed by midsubstance rupture after 8 weeks. Histologically, both groups had similar findings with direct attachments to bone by 12 weeks. CLINICAL RELEVANCE: The tendon graft has the potential to be pulled out of the bone tunnel after complete integration.

Widespread occurrence of eosinophilic neuronal cytoplasmic inclusions in an asymptomatic adult: a novel ubiquitin-negative filamentous inclusion.

We describe a 67-year-old woman without apparent neurological symptoms, in whom postmortem examination revealed widespread occurrence of eosinophilic neuronal cytoplasmic inclusions in the central and peripheral nervous systems. The inclusions were round, oval or rod-like in shape. Immunohistochemically, the inclusions were negative for ubiquitin and not labeled with any other antibodies, except for a partial and weak immunoreactivity with anti-neurofilament occurring rarely. Ultrastructurally, the inclusions revealed two different forms. The common form was entirely composed of bundles of wavy granule-coated filaments (20-30 nm in diameter). The other form consisted of a core containing linear filaments (12-15 nm in diameter) with electron-dense ribosome-like granules and an outer zone with wavy filaments as seen in the former. This inclusion seems to represent a new type of neuronal cytoplasmic inclusion.

Expression of syndecan-1 and E-cadherin is inversely correlated with poor patient's prognosis and recurrent status of extrahepatic bile duct carcinoma.

Extrahepatic bile duct carcinoma is one of the most extremely aggressive cancers with poor prognosis after curative resection. Syndecan-1 and E-cadherin are transmembrane glycoproteins, and have important roles in cell-cell adhesion and tumor progression. In this study, we examined 84 surgically resected cases of extrahepatic bile duct adenocarcinoma to clarify clinicopathological significance of syndecan-1/E-cadherin expression. Reduced expressions of syndecan-1 and Ecadherin were found in 69.0% (58/84) and 46.4% (39/84) of the bile duct carcinomas. Reduced syndecan-1 expression was correlated with lymphatic/venous/nervous invasion (P < 0.0001), and was associated with short overall survival (P = 0.0002). Reduced E-cadherin expression was correlated with lymphatic and nervous invasion (P = 0.008, P < 0.0001, respectively), and was associated with short overall survival (P = 0.0038). The results indicated that reduced syndecan-1/E-cadherin expression may be good indicators of recurrence and prognosis in extrahepatic bile duct carcinoma.

Passage-affected competitive regulation of osteoprotegerin synthesis and the receptor activator of nuclear factor-kappaB ligand mRNA expression in normal human osteoblasts stimulated by the application of cyclic tensile strain.

Mechanical stress application is a unique method for bone studies. We have reported regulation via the p38 mitogen-activated protein kinase (MAPK) pathway in osteoblasts under application of cyclic tensile strain (CTS), among many reports on the extracellular signal-regulated kinase (ERK) 1/2 pathway during mechanical stress, and questions remain as to the differences between our findings and those of others regarding types of MAPK activation. In the present study, osteoblasts were used after the third passage and stimulated by the application of 7%, 0.25 Hz CTS for 3 days, 4 h/day. CTS-induced osteoprotegerin (OPG) synthesis in osteoblasts increased at the third passage and decreased at the fifth passage, whereas CTS-induced receptor activator of nuclear factor-kappaB ligand (RANKL) mRNA expression decreased in osteoblasts at the third passage and increased at the fifth passage. Increases in CTS-induced osteopontin (OPN) synthesis, cyclooxygenase-2 (Cox-2) mRNA expression, and nitric oxide (NO) production by osteoblasts did not change at the third and fifth passages. Furthermore, p38 MAPK at the third passage and ERK1/2 at the fifth passage were found to be competitively activated in osteoblasts by the application of CTS. Based on these results, osteoblasts were shown to be affected by the number of passages. It was suggested that the examination of passage-affected characteristics of osteoblasts might not only be pertinent to the analysis of cellular senescence and in vivo models of bone remodelling with aging but could also be useful in the development of bone tissue engineering.

An aggressive course of Xp11 translocation renal cell carcinoma in a 28-year-old man.

Cases of renal cell carcinoma (RCC) associated with Xp11 translocations are rare and are reported predominantly in children. We report a case of a young man who developed an aggressive Xp11 translocation RCC. A 28-year-old man presented with back pain, fever and macroscopic hematuria. Computed tomography of the abdomen showed a heterogeneous mass in the left kidney. Left radical nephrectomy was performed. Hematoxylin-eosin staining revealed nested and papillary architecture, clear and eosinophilic cytoplasm and vesicles with prominent nucleoli. Immunohistochemical evaluation revealed that the tumor cells showed nuclear labeling for TFE3 protein. On the basis of these findings, the case was diagnosed as Xp11 translocation RCC. This tumor massively recurred and led to the patient's death 2 years after the initial diagnosis. The utility of immunohistochemistry using antibodies against TFE3 in RCC occurring in young adults may be necessary for accurate diagnosis.

Cardiac tumor comprising two components including typical myxoma and atypical hypercellularity suggesting a malignant change.

BACKGROUND: Cardiac myxoma is a benign neoplasm and is not considered to carry a risk of malignant transformation. We describe a case of a cardiac tumor comprising typical myxoma and atypical cellular parts. METHODS AND RESULTS: A 72-year-old woman was found to have a tumor in the left atrial chamber after undergoing echocardiographic investigation and so she underwent tumor excision surgery. The excised tumor was composed of two components with different features with a smooth transition from one type to the other. The apex of the tumor showed a gelatinous and villous appearance on gross examination, and histological examination revealed that the tumor cells had small oval nuclei and eosinophilic cytoplasm and were arranged in cords and vasoformative structures in the myxoid matrix. The base of the tumor appeared as a solid mass on gross examination with hypercellular proliferation of spindle-shaped tumor cells and intersecting fascicles observed histologically. Nuclear mitosis was seen in more than 10/10 high-power fields, coagulation necrosis was prominent, and invasion of the atrial wall was seen. On immunohistochemistry, the tumor cells were found to be positive for alpha-smooth muscle actin, calretinin, and CD34, and this immunoreactivity was decreased at the tip. Ki-67 labeling index was increased at the apex. CONCLUSIONS: We diagnosed this tumor as cardiac myxoma with an atypical hypercellular component suggesting a malignant change. It is important to recognize that a cardiac myxoma could be accompanied by atypical change.

In vivo chemotherapeutic profile of human gallbladder small cell carcinoma.

Small cell carcinoma of the gallbladder is very rare, but shows high malignant potential with frequent metastasis. Chemotherapeutic regimens for the treatment of gallbladder small cell carcinoma have not yet been established. In this study, we examined in vivo chemosensitivity tests for the GB-04-JCK human gallbladder small cell carcinoma, which were previously established as a serial-transplantable xenograft in nude mice. We used four anticancer drugs: docetaxel, irinotecan, nedaplatine and gemcitabine. Docetaxel maximally suppressed xenograft tumor growth in mice (P<0.01), and showed complete tumor regression after chemotherapy day 35. Irinotecan and nedaplatine suppressed tumor growth without complete regression (P<0.01). Gemcitabine did not affect tumor growth significantly. This in vivo experimental study proposed chemotherapeutic regimens for human gallbladder small cell carcinoma.

Immunohistochemical detection of carcinoma in radical prostatectomy specimens following hormone therapy.

Following hormone therapy, residual carcinoma is frequently difficult to identify on HE-stained prostatectomy specimens. The aim of the present study was therefore to investigate whole-mounted specimens obtained by radical prostatectomy from patients who had undergone hormone therapy. Formalin-fixed and paraffin-embedded specimens were immunostained with prostate secretory cell markers including prostate-specific antigen (PSA), P504S (alpha-methylacyl-coenzyme A racemase, AMACR), P501S (prostein), and prostate-specific membrane antigen (PSMA). Residual carcinoma was detected in 250 histological slides of 42 patients in a total of 497 slides from 45 patients. In five of 250 slides (2%), carcinoma was not able to be recognized on HE-stained slides, but was found on the immunohistochemistry slides. PSMA had reacted positively beyond a moderate degree in carcinoma from all patients. PSA was positive for carcinoma in most of the patients, while negative or minimal staining was observed in a small number of patients. Carcinoma was positively reactive with P504S and P501S in most of the patients, but was negatively reactive in a few. The Gleason score for a pretreatment needle biopsy correlated with P504S staining of the prostatectomy specimens. P504S and P501S had limited ability to identify degenerated carcinoma. PSMA was the most useful marker to identify carcinoma after hormone therapy.

Claudin-1 expression is induced by tumor necrosis factor-alpha in human pancreatic cancer cells.

Claudin-1 is a membrane protein with four transmembrane domains, that is exclusively localized at cellular tight junctions. Recent studies have reported that claudin-1 plays an important role in cancer invasion and metastasis. However, the significance of claudin-1 in pancreatic cancer is still unknown. In the present study, we investigated the role of claudin-1 expression in pancreatic cancer growth using the PANC-1 human pancreatic cancer cell line. Treatment with tumor necrosis factor-alpha (TNF-alpha), an inflammatory cytokine, resulted in increased detection of 89 kDa products of poly-(ADP-ribose) polymerase (PARP), a marker of apoptosis, and decreased PANC-1 cell proliferation by 23%. Expression of claudin-1 was up-regulated by TNF-alpha in a concentration-dependent manner in PANC-1 cells. PANC-1 cells treated with TNF-alpha and siRNA against claudin-1 showed a 15% increase in proliferation; i.e. the cells transfected with siRNA against claudin-1 showed resistance to TNF-alpha-induced apoptosis. These results suggest that claudin-1 expression is responsible for TNF-alpha-dependent growth signals and the proliferation of pancreatic cancer cells.