A multicenter prospective registration study on laparoscopic pancreatectomy in Japan: report on the assessment of 1,429 patients.

BACKGROUND: Prospective studies are needed to understand the safety and feasibility of laparoscopic pancreatectomy. The aim of the present study was to describe laparoscopic pancreatectomy currently undertaken in Japan, using a prospective registration system. METHODS: Patient characteristics and planned operations were registered preoperatively, and then the performed operation and outcomes were reported using an online system. Collected data were also compared between institutions based on their level of experience. This study was registered with UMIN000022836. RESULTS: Available data were obtained from 1,429 patients at 100 Japanese institutions, including 1,197 laparoscopic distal pancreatectomies (LDPs) and 232 laparoscopic pancreatoduodenectomies (LPDs). The rates of completion for planned operations were 92% for LDP and 91% for LPD. Postoperative complication rates after LDP and LPD were 17% and 30%, and 90-day mortality rates were 0.3% and 0.4%, respectively. Shorter operation time, less blood loss, and lower incidence of pancreatic fistula were observed in institutions experienced in LDP. A higher rate of pure laparoscopic procedure and shorter operation time were noted in institutions experienced with LPD. CONCLUSION: LDPs and LPDs are performed safely in Japan, especially in experienced institutions. Our data could support the next challenges in the field of laparoscopic pancreatectomy.

Adenovirus vectors with chimeric type 5 and 35 fiber proteins exhibit enhanced transfection of human pancreatic cancer cells.

Adenovirus (Ad) vectors are widely used for gene transfer. Efficient gene transfer into malignant cells is an important requirement for anticancer gene therapy, but transgene expression after transfer with adenoviral vectors varies among different cancer cell lines. Recently, Ad vectors containing chimeric type 5 and 35 fiber proteins have been developed. We evaluated the expression of coxsackie and adenovirus receptor (CAR), as well as integrins alphaV, beta3 and beta5, in seven human pancreatic cancer cell lines and assessed the relationship between expression of these molecules and Ad transfection efficiency. We compared the transfection efficiency of a conventional type 5 Ad vector (Ad5GFP) with that of an Ad vector containing chimeric type 5 and 35 fiber proteins (Ad5/35GFP), which expressed green fluorescent protein (GFP) driven by the cytomegalovirus promoter. There was strong CAR expression by AsPC-1, CFPAC-1 and PANC-1 cells, whereas the other cell lines showed weak expression. There was strong integrin beta3 expression by MIAPaCa-2, PANC-1 and Suit-2 cells, but expression by AsPC-1, BxPC-3, CFPAC-1 and HPAC cells was weak. Transfection efficiency of the vectors for human pancreatic cancer cell lines was not directly related to the CAR or integrin expression. However, transfection by Ad5/35GFP was significantly greater than by Ad5GFP at MOIs of 10 and 25 in all five human pancreatic cell lines. In conclusion, the Ad5/35GFP vector mediates more efficient gene transfer to human pancreatic cancer cells. These results may have implications for improving the efficiency of Ad-mediated gene transfer and developing adenoviral vectors.

Midkine promoter-based conditionally replicative adenovirus therapy for midkine-expressing human pancreatic cancer.

BACKGROUND: To develop a novel therapeutic strategy for human pancreatic cancer using a midkine promoter-based conditionally replicating adenovirus. METHODS: We examined midkine mRNA expression and midkine protein expression by seven human pancreatic cancer cell lines (AsPC-1, BxPC-3, CFPAC-1, HPAC, MIAPaCa-2, PANC-1, and Suit-2), as well as by non-cancerous pancreatic tissue and pancreatic cancers. Midkine promoter activity was measured in cancer cell lines by the dual luciferase reporter assay. Adenoviral transduction efficiency was assessed by fluorescent staining of cancer cell lines using adenovirus type 5 containing the green fluorescent protein gene (Ad5GFP). Replication of adenovirus type 5 containing the 0.6 kb midkne promoter (Ad5MK) was assessed by the detection of E1 protein in cancer cell lines. The cytotoxicity of Ad5MK for cancer cells was evaluated from the extent of growth inhibition after viral infection. Infection and replication were also assessed in nude mice with subcutaneous Suit-2 tumors by intratumoral injection of Ad5MK, Ad5GFP, or vehicle. E1a mRNA expression in the treated tumors and expression of the replication-specific adenoviral hexon protein were evaluated. Finally, the anti-tumor activity of Ad5MK against intraperitoneal xenografts of Suit-2 pancreatic cancer cells was examined after intraperitoneal injection of the virus. RESULTS: Both midkine mRNA expression and midkine protein expression were strong in AsPC-1 and CFPAC-1 cell liens, moderate in BxPC-3, HPAC, and Suit-2 cell lines, and weak in PANC-1 and MIAPaCa-2 cell lines. Expression of midkine mRNA was significantly stronger in pancreatic cancers than in non-cancerous pancreatic tissues. The relative luciferase activity mediated by the 0.6 kb midkne fragment in AsPC-1, PANC-1, and Suit-2 cell lines was approximately 6 to 20 times greater than that in midkne-negative MIAPaCa-2 cell lines. Pancreatic cancer cell lines exhibited a heterogeneous adenoviral transduction profile. E1A expression was higher in cell lines with strong midkine expression than in cell lines with weak midkine expression. Ad5MK showed much greater cytotoxicity for midkine-expressing Suit-2 and PANC-1 cell lines than for midkine-negative MIAPaCa-2 cell lines. In the Suit-2 subcutaneous xenograft model, expression of E1A was detected in Ad5MK-treated tumors, but not in untreated and Ad5GFP-treated tumors. In the Suit-2 intraperitoneal xenograft model, the Ad5MK group survived for significantly longer than the Ad5GFP, PBS, and untreated groups. CONCLUSION: Ad5MK has an anti-tumor effect against human pancreatic cancer cell lines that express midkine mRNA. Midkine promoter-based conditionally replicative adenovirus might be a promising new gene therapy for pancreatic cancer.

Effect of the XIAP inhibitor Embelin on TRAIL-induced apoptosis of pancreatic cancer cells.

BACKGROUND: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent inducer of apoptosis in a wide variety of tumor cells, while it has no toxicity for the majority of normal cells.Therefore, TRAIL may be a suitable agent for anticancer therapy. We previously reported that a number of pancreatic cancer cell lines show resistance to TRAIL-induced apoptosis via overexpression of XIAP and FLIP. The present study was conducted to further examine TRAIL-based therapeutic strategies by aiming to restore functional apoptotic pathways in resistant pancreatic cancer cells. METHODS: In various pancreatic cancer cell lines, TRAIL-induced apoptosis was evaluated in the presence or absence of an XIAP-inhibitor (Smac peptide). Second, TRAIL-induced apoptosis was evaluated in TRAIL-resistant AsPC-1 cells with or without FLIP antisense. Third, the combined effect of Smac peptide and FLIP antisense was tested, and the activation of apoptosis-related caspases and poly (ADP-ribose) polymerase was evaluated. Finally, TRAIL-induced apoptosis was evaluated in the presence or absence of FLIP antisense and an XIAP inhibitor (embelin). RESULTS: Smac peptide enhanced TRAIL-induced apoptosis in a dose-dependent manner for several pancreatic cancer cell lines, but showed no effect on TRAIL-resistant AsPC-1 cells. Smac peptide alone had no influence on cell viability. TRAIL-induced apoptosis was restored in TRAIL-resistant AsPC-1 cells by exposure to FLIP antisense, which suppressed the expression of FLIP. The effect of TRAIL was augmented by the combination of FLIP antisense and Smac peptide. Similarly, TRAIL-induced apoptosis was restored by the combination of FLIP antisense and embelin. Activation of apoptotic caspases and cleavage of poly (ADP-ribose) polymerase was observed after sensitization of TRAIL-resistant pancreatic cancer cells. CONCLUSIONS: Pancreatic cancer cells gain resistance to TRAIL-induced apoptosis via expression of the antiapoptotic proteins XIAP and FLIP. Smac peptide and FLIP antisense could restore the apoptotic effect of TRAIL. An XIAP inhibitor, embelin, enhanced the effect of TRAIL in the presence of FLIP antisense. These findings may provide useful information for the development of TRAIL-based therapeutic strategies by restoring functional apoptotic pathways in resistant pancreatic cancer cells. In addition, a low molecular weight XIAP inhibitor like embelin could be a lead compound for the development of effective XIAP inhibitors.

Bcl-XL antisense oligonucleotides coupled with antennapedia enhances radiation-induced apoptosis in pancreatic cancer.

BACKGROUND: Pancreatic cancer is highly resistant to radiation and chemotherapy, and its resistance reflects the enhancement of apoptosis inhibitory genes, including Bcl-2 family. Antennapedia (pAnt) is capable of almost 100% internalization into cells through the lipid bilayer without any cytotoxic effect. The aim of this study was to examine the effects of the Bcl-XL antisense oligonucleotide for radiosensitivity of in vitro and in vivo pancreatic cancer using oligonucleotide conjugated with antennapedia. METHODS: In in vitro experiments, expression of Bcl-XL protein was examined in 5 pancreatic cancer cell lines. In AsPC-1 cells, internalization of the oligonucleotide was confirmed, and the effects of antennapedia-antisense (pAnt-AS) or antennapedia-scramble (pAnt-Scr) on Bcl-XL protein expression were examined. Cells were treated with pAnt-AS, pAnt-Scr or phosphorothioate antisense (S-AS) for 3 days, then the effects of irradiation on the cell survival, caspase-3 activity, and apoptotic index were evaluated. In AsPC-1 xenograft mice, pAnt-AS, pAnt-Scr, or S-AS was injected, and 5 or 10 Gy irradiation was added. Bcl-Xl protein expression was measured before irradiation. Apoptosis was evaluated at 48 hours after irradiation. On the 14th day after 10-Gy irradiation, tumor wet weight was measured, and tumor growth was estimated over 5 weeks. RESULTS: In in vitro experiments, all pancreatic cancer cell lines expressed Bcl-XL protein. pAnt-AS was internalized into AsPC-1 cells within 2 hours. pAnt-AS at 10 mumol/L reduced more than 90% of the Bcl-XL protein in AsPC-1 cells, whereas pAnt-Scr or S-AS treatment at the same concentration reduced as much as 10% of the Bcl-XL protein. Treatment with pAnt-AS followed by irradiation significantly reduced cell viability when compared with that of pAnt-Scr or S-AS. Caspase-3 activity was significantly upregulated in the pAnt-AS-treated group (P = .033). The rate of nuclear fragmentation was significantly higher in the pAnt-AS group (P = .013). In in vivo experiments, Bcl-XL protein was reduced about 40% in the pAnt-AS-treated mice. Tumor doubling time of the pAnt-AS-treated mice was elongated by 10-Gy irradiation. The tumor wet weight of mice treated with pAnt-AS and 10-Gy irradiation was significantly reduced when compared with mice treated with pAnt-Scr and 10-Gy irradiation (P = .046). The apoptosis index at 48 hours after irradiation was significantly increased in pAnt-AS-treated mice (P < .01). CONCLUSIONS: The results suggest that, when coupled with antennapedia, the antisense oligonucleotide against Bcl-XL could be a good therapeutic tool for radiosensitization of pancreatic cancer.

Clinical significance of focal adhesion kinase in resectable pancreatic cancer.

Focal adhesion kinase (FAK) is a non-receptor, cytoplasmic protein tyrosine kinase that is involved in the regulation of cellular signaling, migration, apoptosis, and cell cycle progression. Previous reports have shown that FAK is expressed in various kinds of cancer tissues and cancer cell lines; however, no information is available about human pancreatic carcinoma specimens. Tissue such specimens were obtained from 50 patients who underwent pancreatic resection for pancreatic invasive ductal carcinoma at our institute from 1996 to 2002. Immunohistochemical analysis of FAK was performed in the resected specimens. Focal adhesion kinase expression in seven human pancreatic cancer cell lines was analyzed by reverse transcription polymerase chain reaction (PCR) analysis and Western blot analysis. Focal adhesion kinase expression was detected in 24 of 50 cases (48%). There was a statistically significant correlation between FAK expression and tumor size (P=0.004), although FAK expression did not significantly correlate with other factors such as tumor histological grade, lymph node metastasis, distant metastasis, histological stage, and overall survival. Reverse transcription PCR analysis and Western blot analysis showed that FAK was expressed in all seven pancreatic cancer cell lines. Focal adhesion kinase expression was not directly related to clinicopathological factors except tumor size in pancreatic carcinoma. Focal adhesion kinase expression may not be a prognostic marker for pancreatic cancer patients.

In vivo antitumor effect of the mTOR inhibitor CCI-779 and gemcitabine in xenograft models of human pancreatic cancer.

Mammalian target of rapamycin (mTOR) is considered to be a major effector of cell growth and proliferation that controls protein synthesis through a large number of downstream targets. We investigated the expression of the phosphatidylinositol 3'-kinase (PI3K)/mTOR signaling pathway in human pancreatic cancer cells and tissues, and the in vivo antitumor effects of the mTOR inhibitor CCI-779 with/without gemcitabine in xenograft models of human pancreatic cancer. We found that the Akt, mTOR and p70 S6 kinase (S6K1) from the PI3K/mTOR signaling pathway were activated in all of the pancreatic cancer cell lines examined. When surgically resected tissue specimens of pancreatic ductal adenocarcinoma were examined, phosphorylation of Akt, mTOR and S6K1 was detected in 50, 55 and 65% of the specimens, respectively. Although CCI-779 had no additive or synergistic antiproliferative effect when combined with gemcitabine in vitro, it showed significant antitumor activity in the AsPC-1 subcutaneous xenograft model as both a single agent and in combination with gemictabine. Furthermore, in the Suit-2 peritoneal dissemination xenograft model, the combination of these 2 drugs achieved significantly better survival when compared with CCI-779 or gemcitabine alone. These results demonstrate promising activity of the mTOR inhibitor CCI-779 against human pancreatic cancer, and suggest that the inhibition of mTOR signaling can be exploited as a potentially tumor-selective therapeutic strategy.

Expression and prognostic value of tuberous sclerosis complex 2 gene product tuberin in human pancreatic cancer.

BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutation of either of 2 tumor suppressor genes, TSC1 or TSC2, which encode hamartin and tuberin, respectively. Several studies have shown that tuberin functions independently of hamartin and inhibits signaling pathways via the mammalian target of rapamycin, a critical regulator of cell proliferation. Recent studies have revealed that the signaling pathways regulating the mammalian target of rapamycin such as Akt and S6K1 are frequently activated in pancreatic cancer. We hypothesized that tuberin might be involved in the proliferation and survival of pancreatic cancer cells. METHODS: We immunohistochemically examined the expression of tuberin in 42 pancreatic cancerous and noncancerous pancreatic tissue specimens using an antituberin antibody. The correlations between tuberin expression and various clinicopathologic features, including survival, were evaluated. Reverse transcriptase-polymerase chain reaction was performed to evaluate the level of tuberin expression in paired samples of pancreatic cancer and noncancerous tissue. RESULTS: Twenty-four of the 42 pancreatic cancer samples (57%) were negative for tuberin expression. The patients with tuberin-negative tumors had a significantly higher incidence of pT3 or pT4 disease (primary tumor extent by the TNM classification) than those with tuberin-positive tumors (P = .024). Female patients had a significantly higher incidence of tuberin-positive tumors than male patients (P = .014). The survival rate of the tuberin-positive group tended to be better than that of the tuberin-negative group, but there was no significant difference (P = .4). Expression of TSC2 in cancer tissue was lower than in the corresponding noncancerous tissue for 7 of the 9 samples examined. CONCLUSIONS: This study demonstrates that reduced expression of tuberin might be involved in the progression of pancreatic cancer. Accordingly, tuberin may provide a new therapeutic target in patients with this type of cancer.

Pancreatic epithelial cells can be converted into insulin-producing cells by GLP-1 in conjunction with virus-mediated gene transfer of pdx-1.

BACKGROUND: Glucagonlike peptide-1 (GLP-1) stimulates insulin secretion and proliferation by islet cells in vitro and in vivo, associated with an activation of pancreatic duodenal homeobox gene-1 (pdx-1) function. The effect of GLP-1 on the conditionally immortalized pancreatic epithelial cells (IMPE cells) is not clear when they are treated in conjunction with the adenovirus-mediated gene transfer of pdx-1. METHODS: IMPE cells were established from the pancreas of H-2K(b)-tsA58 transgenic mice. IMPE cells were maintained at 33 degrees C with 10 U/mL interferon (IFN)-gamma and the experiments were performed at 39 degrees C without IFN-gamma. IMPE cells were infected with 20 multiplicities of Ad-pdx-1 or control Ad-lacZ at 39 degrees C without IFN-gamma and were incubated with various concentrations of GLP-1. After 48 hours, immunofluorescence and reverse transcriptase-polymerase chain reaction for insulin and pdx-1 expression were examined. Immunoreactive insulin in the cell lysate and supernatant was also analyzed. The glucose concentration in the culture medium was changed to test the insulin secretory responsiveness of the IMPE cells. RESULTS: The treatment with GLP-1 in conjunction with Ad-pdx-1 induced insulin production by IMPE cells, but the treatment with either GLP-1 or Ad-pdx-1 alone failed to induce insulin production. Insulin production and secretion were increased by GLP-1 and by glucose in a dose-dependent manner. In addition, the insulin-producing IMPE cells acquired a rapid insulin secretory responsiveness to the changes of extracellular glucose concentration. CONCLUSIONS: GLP-1 and pdx-1 work together to induce insulin-producing cells from IMPE cells, which bear unique characteristics of pancreatic ductal cells. The results suggest that GLP-1 may be another important determiner of pancreatic endocrine differentiation as is pdx-1.

Downregulation of survivin by siRNA diminishes radioresistance of pancreatic cancer cells.

BACKGROUND: Survivin is a member of the inhibitor of apoptosis protein family, which inhibits apoptosis and regulates cell division. Survivin is expressed by the majority of human cancers, including pancreatic adenocarcinoma. We have reported that its expression is correlated with shorter survival of pancreatic cancer patients, so regulation of this molecule could be a new strategy for fighting pancreatic cancer. METHODS: In 3 pancreatic cancer cell lines (AsPC-1, SUIT-2, and Panc-1), survivin promoter activity was determined by the luciferase reporter assay, and survivin messenger RNA (mRNA) expression was examined by quantitative reverse transcriptase-polymerase chain reaction. The dose-dependent cytotoxity of radiation was also assessed, while caspase-3 activity and induction of DNA fragmentation were evaluated. Furthermore, the effect of silencing or nonsilencing short interfering RNA (siRNA) expression plasmids directed against the survivin gene on AsPC-1 cells, the most radioresistant cell line, was evaluated. RESULTS: Pancreatic cancer cell lines expressed varying levels of survivin mRNA in association with transcriptional activity of the survivin promoter. Both survivin promoter activity and mRNA expression were correlated with tumor cell radiosensitivity. Radiation significantly increased survivin promoter activity and survivin mRNA expression in all cell lines. Radiation induced a significant increase in caspase-3 activity and DNA fragmentation in AsPC-1 cells. After silencing siRNA treatment of AsPC-1 cells (AS-S cells), there was a significant decrease in survivin mRNA expression and increase in caspase-3 activity, compared with the effect of nonsilencing scramble siRNA on AsPC-1 cells (AS-NS cells). AS-S cells were more radiosensitive than AS-NS cells. Radiation induced higher caspase-3 activity and more DNA fragmentation in AS-S cells, compared with AS-NS cells. CONCLUSIONS: Survivin may play an important role as 1 of the radioresistance factors. Downregulation of survivin by siRNA can diminish the radioresistance of pancreatic cancer cells, so combined therapy with survivin inhibition and radiation may be useful for the treatment of pancreatic cancer.

Regulation of the resistance to TRAIL-induced apoptosis as a new strategy for pancreatic cancer.

BACKGROUND: Tumor necrosis factor-related, apoptosis-inducing ligand (TRAIL) is a potent inducer of apoptosis in a wide variety of tumor cells, but it does not cause toxicity in the majority of normal cells. Therefore, TRAIL could become a suitable agent for anticancer therapies. However, a number of tumor cell lines are known to be resistant to TRAIL-induced apoptosis. The purpose of this study was to determine the mechanisms of resistance to TRAIL in pancreatic cancer cells. METHODS: In human pancreatic cancer cell lines, the sensitivity to TRAIL-induced apoptosis was tested. The expression of TRAIL receptors (DR4, DR5, DcR1, and DcR2) and the expression of death signal-transducing proteins were investigated. In the TRAIL-resistant pancreatic cancer cells, effects of cycloheximide, a protein synthesis inhibitor, on death signal-transducing proteins were tested. Finally, the effects of the combined treatment with cycloheximide and TRAIL on the induction of apoptosis and on the expression of death signal-transducing proteins were examined. RESULTS: Pancreatic cancer cells responded to TRAIL in a different way. Resistant cell lines, AsPC-1, Suit-2, and CFPAC-1, expressed higher levels of FLIP-S protein, one of the splice variants of FLIP. Cycloheximide reduced the expression of FLIP in the resistant cells. Combined treatment with cycloheximide and TRAIL induced cleaved forms of caspases and simultaneously restored the sensitivity to TRAIL-induced apoptosis in the resistant cells. CONCLUSIONS: Pancreatic cancer cells are resistant to TRAIL-induced apoptosis via strong expression of the anti-apoptotic protein FLIP-S. Suppression of FLIP-S by cycloheximide restored sensitivity to TRAIL-induced apoptosis in resistant cancer cells. These findings may provide useful information for the development of TRAIL-based therapeutic strategies aimed at restoring the functionality of apoptotic pathways in pancreatic cancer cells.

Analysis of E-, N-cadherin, alpha-, beta-, and gamma-catenin expression in human pancreatic carcinoma cell lines.

OBJECTIVES: Cadherins are cell surface glycoproteins that mediate Ca2+-dependent, homophilic cell-cell adhesion. The classic cadherins interact with either beta-catenin or gamma-catenin, which is bound to alpha-catenin that links the complex to the actin cytoskeleton. It has been reported that alteration in cadherins/catenins function or expression is found in the neoplastic process as a step in metastasis. The aim of this study was to analyze the expressions of E- and N-cadherins and catenins in human pancreatic cancer cell lines. METHODS: We examined the expression of cadherins and catenins in 7 human pancreatic cancer cells by RT-PCR, Western blotting, and immunocytochemistry. The interactions between cadherins and beta-catenin were assessed by immunoprecipitation. RESULTS: E-cadherin was expressed in all cell lines except for MIAPaCa-2, whereas N-cadherin was expressed in Capan-2, CFPAC-1, BxPC-3, and PANC-1. The alpha-, beta-, and gamma-catenins were expressed and cadherins/beta-catenin interactions were detected in all cadherin-expressing cells. Immunocytochemical analysis showed membranous expression of cadherins and catenins. CONCLUSION: The decreased or loss of cadherins and catenins expression could be involved in the tumor progression and metastasis, although these events may occur in in vivo conditions by interaction between cancer cells and extracellular matrices.

Chronic exposure of transforming growth factor beta 1 confers a more aggressive tumor phenotype through downregulation of p21(WAF1/CIP1) in conditionally immortalized pancreatic epithelial cells.

BACKGROUND: Recent studies have demonstrated that transforming growth factor beta 1 (TGF-beta1) expression is markedly enhanced in invasive ductal pancreatic adenocarcinomas, although the precise role of TGF-beta1 in pancreatic carcinogenesis remains unclear. We analyzed TGF-beta1 expression in pancreatic intraepithelial neoplasias (PanINs) and the effects of chronic TGF-beta1 exposure on conditionally immortalized pancreatic epithelial (IMPE) cells. METHODS: Sixty-one PanIN lesions were immunohistochemically stained with a polyclonal rabbit antibody against human TGF-beta1. Growth-inhibitory effects of short-term exposure to TGF-beta1 were examined in IMPE cells. IMPE cells resistant to TGF-beta1 (IMPE-Tr cells) were generated by continuous exposure to 1 ng/mL of TGF-beta1 for more than 50 days. Phenotypic alterations of IMPE-Tr cells were examined by soft agar and Matrigel assay and Western blot analysis. IMPE and IMPE-Tr cells were injected subcutaneously into nude mice for an in vivo tumorigenicity assay. RESULTS: Forty-six percent of PanINs (28/61) were positive for TGF-beta1 expression, whereas all the epithelia of normal pancreatic ducts were negative. TGF-beta1 treatment showed the marked growth-inhibitory effects (>75%) in IMPE cells, whereas its effects were not observed in IMPE-Tr cells. IMPE-Tr cells were more spindle shaped compared with IMPE cells. In soft agar and Matrigel, formations of many colonies were observed in IMPE-Tr cells, but not in IMPE cells. Interestingly, the expression of p21(WAF1/CIP1) was induced by short-term exposure to TGF-beta1 in IMPE cells, whereas the induction was decreased in IMPE-Tr cells. All of the IMPE-Tr cell-injected mice (5/5) had subcutaneous tumors, although no tumor was found in the IMPE cell-injected mice. CONCLUSIONS: TGF-beta1 expression in PanINs and neoplastic transformation of IMPE cells by long-term exposure to TGF-beta1 suggest that TGF-beta1 may act as a tumor promoter in the early stage of pancreatic carcinogenesis.

Survivin expression is a prognostic marker in pancreatic cancer patients.

BACKGROUND: In this study, we assessed survivin expression in pancreatic cancer specimens from patients who underwent either pancreatic resection alone or pancreatic resection plus postoperative radiation therapy (PORT) to evaluate whether survivin expression is predictive of sensitivity to PORT and outcome in pancreatic cancer patients. METHODS: Fifty-two patients who underwent pancreatic resection for ductal adenocarcinomas were included in this study. Forty-seven pancreatic ductal adenocarcinoma and 5 normal pancreatic tissues were evaluated for survivin expression by immunohistochemistry. Then the relationship between survivin expression and clinicopathologic data were analyzed. RESULTS: Sixty-eight percent (32/47) of pancreatic cancer tissues were positive for survivin expression; 32% (15/47) were negative. Normal pancreatic exocrine tissues were negative for survivin expression (0/5). Survival of the patients with positive survivin was significantly shorter than those with negative survivin (P = .02). Survivin was an independent variable that correlated with overall survival (P = .01). There was no difference in survival time between patients with and without PORT. Likely, PORT showed no impact on survival time in survivin-positive patients (P = .12) as well as in survivin-negative patients (P = .95). CONCLUSIONS: The results suggest that survivin expression in pancreatic cancer tissues could be a useful prognostic marker in pancreatic cancer patients.

Hepatic regeneration and enforced PDX-1 expression accelerate transdifferentiation in liver.

BACKGROUND: Pancreatic duodenal homeobox gene-1 (PDX-1) has a dual task as a key regulator in pancreatic organogenesis and in functional maintenance of beta cells in adults. Recent studies have shown a close lineage relationship between the liver and the pancreas. In this study, we analyzed the plasticity of the liver by enforced expression of PDX-1 in streptozotocin (STZ)-treated mice under the condition of hepatic regeneration. METHODS: Replication-deficient adenoviruses were constructed by the cosmid-adenoviral DNA terminal protein complex method. Mice were treated with STZ (200 mg/kg ip), and a 40% partial hepatectomy was performed at day 0. After 24 hours, Ad-pdx-1 or Ad-lacZ 2.0 x 10(9) PFU/body was injected via the tail vain into nontreated (control), STZ-treated, or STZ plus partial hepatectomy (Hx)-treated ICR mice. After 7 and 14 days, expression of PDX-1 and islet hormones was examined by immunohistologic and reverse transcription-polymerase chain reaction analysis. Blood glucose concentrations were measured every 2 days. Immunoreactive insulin (IRI) of serum and liver extract was measured by ELISA. RESULTS: Most hepatocytes of Ad-pdx-1-infected mice were positive for PDX-1 expression by immunohistochemistry. In nontreated mice, very few cells expressed insulin and other hormones. In contrast, insulin and somatostatin were expressed in STZ-treated mice, and more cells were expressed in STZ plus Hx-treated mice. In addition, other beta-cell markers like GLUT2 and glucokinase were observed. Hyperglycemia was improved in STZ-treated mice and STZ plus Hx-treated mice. IRI of serum and liver extract was increased in STZ-treated mice and STZ plus Hx-treated mice. The insulin positive area of the liver in STZ plus Hx-treated mice was larger than that in nontreated and STZ-treated mice. CONCLUSIONS: Ectopic PDX-1 expression alone may be insufficient to induce insulin-producing cells in the liver. STZ-induced hyperglycemia plus partial hepatectomy that leads to diabetic state and hepatic regeneration may stimulate the transdifferentiation of liver cells into insulin-producing cells.

Conditional transformation of mouse pancreatic epithelial cells: an in vitro model for analysis of genetic events in pancreatocarcinogenesis.

Pancreatic ductal adenocarcinomas arise through the accumulation of certain genetic alterations including ras, p16, p53, and DPC4. We found that activation of ras and inactivation of p53 could cooperatively induce in vitro tumorigenicity in conditionally immortalized pancreatic epithelial (IMPE) cells. IMPE cells were established from transgenic mice bearing a temperature-sensitive mutant SV40 Large T (LT) antigen. IMPE cells grew continuously under permissive conditions (33 degrees C with interferon-gamma), but rapidly suffered growth arrest under non-permissive conditions (39 degrees C without interferon-gamma). The cells showed strong expression of E-cadherin and beta-catenin as epithelial markers, and cytokeratin 19, a specific ductal cell marker. Cell proliferation under permissive conditions was associated with down-regulation of p21 expression through inactivation of p53 after overexpression of LT antigen. Intriguingly, the shift from the permissive to non-permissive culture conditions caused G2/M arrest of IMPE cells. Although the cells did not form colonies when cultured in soft agar without activation of ras, cells with ras activation via an adenovirus vector formed colonies under permissive conditions. These findings suggest that activation of ras and inactivation of p53 can cooperatively induce anchorage-independent growth of IMPE cells. This cell line might be useful for studying the processes involved in pancreatocarcinogenesis.

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)beta, 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.

Metastin and its variant forms suppress migration of pancreatic cancer cells.

Metastin, a post-translationally modified variant of KiSS1, was recently identified as an endogenous peptide agonist for a novel G-protein coupled receptor, hOT7T175 (AXOR12, GPR54). In this study, we analyzed the role of KiSS1 and hOT7T175 in both pancreatic cancer tissues and pancreatic cancer cell lines. Furthermore, we synthesized novel short variant forms of metastin and tested the inhibitory effect of those variants on in vitro cell functions that are relevant to metastasis. Pancreatic cancer tissues showed significantly lower expression of KiSS1 mRNA than normal tissues (p=0.018), while cancer tissues showed significantly higher expression of hOT7T175 mRNA than normal pancreatic tissues (p=0.027). In human pancreatic cancer cell lines, KiSS1 mRNA was highly expressed in 2 out of 6 pancreatic cancer cell lines, while hOT7T175 mRNA was expressed in all cell lines at various degrees. PANC-1 cells showed the highest expression of hOT7T175. Exogenous metastin did not suppress cell proliferation but significantly reduced the in vitro migration of PANC-1 cells (p<0.01). Metastin induced activation of ERK1 in PANC-1 and AsPC-1 cells. Finally, we synthesized 3 novel short variant forms of metastin, FM053a2TFA, FM059a2TFA, and FM052a4TFA. These metastin variants significantly suppressed the migration of PANC-1 cells and activated ERK1. These data suggest that the metastin receptor, hOT7T175, is one of the promising targets for suppression of metastasis, and that small metastin variants could be an anti-metastatic agent to pancreatic cancer.

CXCR4 antagonist inhibits stromal cell-derived factor 1-induced migration and invasion of human pancreatic cancer.

The stromal cell-derived factor-1 (SDF-1)/CXCR4 system is implicated in various instances of cell migration in mammals, including the migration of lymphocytes and the formation of metastases. We have recently synthesized a potent novel CXCR4 antagonist, TN14003. The purpose of this study was to investigate the role of SDF-1/CXCR4 axis in the pancreatic cancer metastasis via cell migration and invasion, and the inhibitory effect of TN14003 on pancreatic cancer cell metastasis. The expression of CXCR4 was detected in six pancreatic cancer cell lines by Western blotting and immunocytochemistry. In migration and invasion assays, SDF-1 stimulated both migration and invasion of cancer cells in a dose-dependent manner. The maximal effect of SDF-1 was observed at 100 ng/ml. SDF-1-induced migration and invasion of cancer cells were completely blocked by 100 nM TN14003. The stimulatory effect of SDF-1 on cancer migration and the inhibitory effect of TN14003 were mediated via the alteration in phosphorylation of mitogen-activated protein kinases. Treatment of cancer cells with 100 ng/ml SDF-1 resulted in a significant increase of actin polymerization, which was reduced by 100 nM TN14003. SDF-1 enhanced cancer cell adhesion to laminin, which was not reversed by TN14003. Taken together, SDF-1/CXCR4 axis is involved in pancreatic cancer metastasis through migration and invasion. The small molecule antagonists against CXCR4 such as TN14003 might be an effective anti-metastatic agent for pancreatic cancer.

Increased PDX-1 expression is associated with outcome in patients with pancreatic cancer.

BACKGROUND: During pancreatic development, pancreatic duodenal homeobox gene-1 (PDX-1) is expressed in pancreatic duct cells that have the potential to differentiate into islets. Therefore, PDX-1 is thought to be a marker of de-differentiated cells with the capacity to redifferentiate into several pancreatic cell types. We analyzed PDX-1 expression in human pancreatic cancer specimens, pancreatic cancer cell lines, and the effects of forced expression of PDX-1 in pancreatic cancer cells. METHODS: Thirty-five pancreatic adenocarcinomas were immunohistochemically stained with a polyclonal rabbit antibody against mouse PDX-1. Correlations with tumor characteristics were made with chi-squared analysis. The influence of clinicopathologic factors on survival was assessed. The expression of PDX-1 in pancreatic cancer cells was examined. Replication-deficient recombinant adenoviruses were constructed by the cosmid-adenoviral DNA terminal protein complex method. PANC-1 cells were infected with Ad-pdx-1 or Ad-LacZ. PANC-1 cells that were infected with adenovirus were used in a cell growth assay and a migration assay and for morphologic analysis. RESULTS: Interestingly, 43% of pancreatic cancers were positive for PDX-1 expression, and 57% of pancreatic cancers were negative (normal pancreatic exocrine tissue shows little or no staining for PDX-1). Lymph node metastasis (P =.02) and histologic grade (P =.04) were correlated significantly with PDX-1 expression. Patients with positive PDX-1 had a significantly worse prognosis than those patients with negative PDX-1 (P =.02). Importantly, PDX-1 was an independent variable that effected overall survival (P =.03). Pancreatic cancer cell lines showed no PDX-1 expression. There were no significant differences in cell proliferation or morphologic condition between Ad-pdx-1- and Ad-lacZ-infected PANC-1 cells. However, Ad-pdx-1-infected PANC-1 cells did show a significantly higher migration rate than Ad-lacZ-infected PANC-1 cells. CONCLUSIONS: Re-expression of PDX-1 may represent a return to a more de-differentiated state by more aggressive pancreatic cancers and may also represent an important new tumor marker for these aggressive cancers.