Interleukin-6 produced by pancreatic carcinoma cells enhances humoral immune responses against tumor cells: a possible event in tumor regression

Epithelial-mesenchymal transition via transforming growth factor beta in pancreatic cancer is potentiated by the inflammatory glycoprotein leucine-rich alpha-2 glycoprotein

We previously showed that an inflammation‐related, molecule leucine‐rich alpha‐2 glycoprotein (LRG) enhances the transforming growth factor (TGF)‐β1‐induced phosphorylation of Smad proteins and is elevated in patients with pancreatic ductal adenocarcinoma (PDAC). As TGF‐β/Smad signaling is considered to play a key role in epithelial‐mesenchymal transition (EMT), we attempted to clarify the mechanism underlying LRG‐related EMT in relation to metastasis in PDAC. We cultured LRG‐overexpressing PDAC cells (Panc1/LRG) and evaluated the morphology, EMT‐related molecules and TGF‐β/Smad signaling pathway in these cells. We also assessed the LRG levels in plasma and resected specimens from patients with PDAC. Inflammatory cytokines induced LRG production in PDAC cells. A spindle‐like shape was visualized more frequently than other shapes in Panc1/LRG with TGF‐β1 exposure. The expression of E‐cadherin in Panc1/LRG was decreased with TGF‐β1 exposure. Invasion increased with TGF‐β1 stimulation of Panc1/LRG. The phosphorylation of smad2 in Panc1/LRG was increased in comparison with parental Panc1 under TGF‐β1 stimulation. In the plasma LRG‐high group, the recurrence rate tended to be higher and the recurrence‐free survival (RFS) tended to be worse in comparison with the plasma LRG‐low group. LRG enhanced EMT induced by TGF‐β signaling, thus indicating that LRG has a significant effect on the metastasis of PDAC.

Interleukin-17 acts as double-edged sword in anti-tumor immunity and tumorigenesis

Interleukin-17 (IL-17), a proinflammatory cytokine, mainly produced by Th17 cells, participates in both innate and adaptive immune responses and is involved in various diseases, including infectious diseases, autoimmune disorders and cancer. Emerging evidence indicates that IL-17 not only has an oncogenic role in tumorigenesis by regulating tumor angiogenesis and enhancing tumor immune evasion but also exerts anti-tumor functions by enhancing natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) activation and through the recruitment of neutrophils, NK cells and CD4⁺ and CD8⁺ T cells to tumor tissue. In this review, we provide an overview on the basic biology of IL-17 and recent findings regarding its enigmatic double-edged features in tumorigenesis, with special attention to the roles of IL-17 produced by tumor cells interacting with other factors in the tumor microenvironment.

Interleukin-6: a villain in the drama of pancreatic cancer development and progression

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a poor prognosis and little treatment options. The development and progression of the disease is fostered by inflammatory cells and cytokines. One of these cytokines is interleukin-6 (IL-6), which plays an important role in a wide range of biologic activities.

DATA SOURCES

A systematic search of PubMed was performed to identify relevant studies using key words such as interleukin-6, inflammatory cytokines, inflammation and pancreatic cancer or PDAC. Articles related to IL-6 and pancreatic cancer were systematically reviewed.

RESULTS

IL-6 is elevated in the serum of pancreatic cancer patients and correlates with cachexia, advanced tumor stage and poor survival. Its expression is enhanced by hypoxia and proteins involved in pancreatic cancer development like Kras, mesothelin or ZIP4. IL-6 in turn contributes to the generation of a pro-tumorigenic microenvironment and is probably involved in angiogenesis and metastasis. In experimental mouse models of PDAC, IL-6 was important for the development and progression of precursor lesions.

CONCLUSION

IL-6 emerges as a key player in pancreatic cancer development and progression, and hence should be considered as a new therapeutic target.

Significance of the correlation between the expression of interleukin 6 and clinical features in patients with non-small cell lung cancer

BACKGROUND

The aims of the study were to identify the significance of interleukin (IL)-6 production and to determine whether IL-6 production influences long-term survival in patients with non-small-cell lung cancer (NSCLC).

METHOD

A series of 90 patients with NSCLC who underwent surgery between 2005 and 2007 was analyzed. Preoperative serum IL-6 was measured, and tumor samples were immunohistochemically stained for IL-6.

RESULTS

Serum IL-6 levels were elevated in 43 of 90 cases (47.7%), and 23 (25.5%) of 90 cases stained positively for IL-6 (P = .00265). The prognosis of patients with NSCLC who had positive immunohistochemical staining was significantly worse than that for those who had negative staining, by univariate analysis (P = .0027). Multivariate analysis indicated that tumor size, postoperative stage, and overexpression of IL-6 were independent prognostic factors.

CONCLUSIONS

The expression of IL-6 in tumor correlated with the concentration of serum IL-6, tumor progression, and overall survival in patients with NSCLC.

Immunoglobulin E antibodies from pancreatic cancer patients mediate antibody-dependent cell-mediated cytotoxicity against pancreatic cancer cells

In addition to allergy and parasitic infections, immunoglobulin E (IgE) has been shown recently to possess anti-viral and anti-cancer effects. We investigated serum levels of IgE, its low-affinity receptor, soluble CD23 (sCD23) in patients with pancreatic cancer and the effect of IgE against pancreatic cancer cells. Twelve patients were evaluated for pancreatic cancer by imaging and confirmed by biopsy. Fifteen healthy volunteers served as controls. Serum Igs (IgG, IgM, IgA, IgE) and sCD23 levels were determined (enzyme-linked immunosorbent assay, nephelometry) and the presence of cancer-specific IgE was assessed (fluorescence microscopy, Western blot). IgE anti-cancer activity was determined by antibody-dependent cell-mediated cytotoxicity (ADCC). Serum levels of IgE and sCD23 were elevated significantly in patients with pancreatic cancer versus controls, whereas no differences were observed in other Ig isotypes (IgG, IgM, IgA). Flow cytometry and immunofluorescence microscopy demonstrated similar presence of IgG and IgE pancreatic cancer Igs. However, Western blot analysis indicated differences in IgG and IgE antigen-specific antibodies; IgE antibody recognized a 50 kD protein. ADCC studies demonstrated that serum and purified IgE-mediated cytotoxicity against pancreatic cancer cells, effects which were reversed with anti-IgE neutralizing antibody and IgE depletion (immunoaffinity); greater cytotoxicity was observed in patient serum when compared with healthy controls. These data suggest that IgE and sCD23 may serve as useful biomarkers for patients with pancreatic cancer and may be important in the immune response to this disease in that IgE-directed therapy may help to direct treatment.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

IL-6-174 C/G polymorphism in the gastroenteropancreatic neuroendocrine tumors (GEP-NETs)

IL-6 is a pleiotropic cytokine with still controversial role in tumorigenesis of different cancer types. Its promoter SNP-174 C/G is associated with increased IL-6 transcription and in some tumor types with elevated IL-6 serum levels. The role of IL-6 polymorphisms and IL-6 serum values and their correlation in the gastroenteropancreatic neuroendocrine tumors is lacking. We investigated for the first time frequencies of IL-6-174 genotypes in 80 GEP-NET patients and 162 age- and sex-matched healthy controls, serum values of IL-6 in GEP-NET patients and their correlation with IL-6-174 genotypes. To analyze IL6-174 C/G polymorphism PCR-NlaIII RFLP method was used, and serum levels were measured on Immulite analyzer by enzymatic solid-phase chemiluminescent immunometric method. Serum IL-6 values were elevated (>5.9 pg/ml) in 36.8% GEP-NET patients. Differences in genotypes distribution between patients and healthy controls as well as between patients with gastrointestinal and pancreatic neuroendocrine tumors (PETs) and functioning and nonfunctioning PETs were tested by chi(2) test and Fisher's Exact test. Analysis of variance (ANOVA with proc GLM in SAS/Stat) was performed for the group comparison. Level of significance was alpha=0.05. Patients with nonfunctioning PETs had only high expression IL-6-174 CG and GG genotypes and according to genotypes differed significantly (p=0.0289) from functioning PETs. High serum IL-6 values in all GEP-NET patients correlated significantly with GG IL-6-174 genotype (p=0.0139). Nonfunctioning PET patients had significantly (p=0.000777) higher IL-6 serum values in comparison to patients with functioning PETs and gastrointestinal NETs. Serum IL-6 values correlated significantly with IL-6-174 genotypes in nonfunctioning PETs and gastrointestinal NETs (p<0.05), but not in functioning PETs.

Current update of cytokines in pancreatic cancer: pathogenic mechanisms, clinical indication, and therapeutic values

Pancreatic cancer is the fourth leading cause of cancer death with a 5-year survival less than 5 percent despite rigorous interventions. This largely is due to its late presentation, aggressive metastasis, and a lack of effective adjuvant therapies. Cytokines have been studied in many tumor types, where they have been shown to be an important influence in cancer cell behavior and to have potential as tumor markers, therapeutic targets, or as treatments themselves. Recently, the roles cytokines play in pancreatic cancer have become the subject of intense investigation. However, the story is complicated, largely because of the pleiotropic and overlapping nature of cytokine functions. This article attempts to provide a focused review of recent discoveries in this area by organizing the material along the pathophysiologic tasks a cancer cell must accomplish to achieve malignancy. We examined how cytokines act to create a microenvironment conducive to tumor cell survival and growth, discussed how cytokines affect proliferation, invasion, metastasis, and apoptosis in pancreatic cancer cells, and we summarized how this knowledge has been applied either to target cytokines or use them therapeutically.

Tumor-derived interleukin (IL)-6 induced anti-tumor effect in immune-compromised hosts

Tumor-derived cytokines, such as interleukin (IL)-6, function in the context of tumor-to-host interactions, and their functions in immune-compromised hosts need to be addressed in the light of ever- increasing number of patients under immunosuppression. We studied the effects, in immune-comprised animals, of tumor-derived IL-6 on tumor growth using an experimental tumor vaccination model. Murine mammary carcinoma FM3A clone 25 (CL25) cells, which neither produce IL-6 nor express IL-6 receptors, were used. cDNA for murine IL-6 (mIL-6) was introduced to the CL25 cells, resulting in a high-producer (mIL-6H) clone. In the severe combined immune-deficient (SCID) mice, the inoculation 3 weeks earlier of mIL-6H to a dorsal flank site suppressed the growth of the CL25 cells at the opposite flank site; a tumor-derived IL-6-mediated vaccination effect occurred. In the T-cell-deficient nude mice, the inoculations 4 weeks earlier of mIL-6H suppressed the growth of CL25, but the simultaneous inoculation of these transfectants did not affect the growth of CL25. Reducing the number of inoculated transfectants or a shorter vaccination period obscured the suppressive effect. The amounts of circulating tumor-reactive immunoglobulin did not correlate with the suppressive effect. The subcutaneous injection of the anti-CD40 antibody generated a further suppression of tumor growth in the mIL-6H-inoculated, but not in the mock-inoculated, T-cell-deficient mice. In the immune-competent hosts, a suppressive effect was not observed. Natural killer (NK) activity was augmented in the spleen of mIL-6H-inoculated scid mice. This study indicated a possible vaccination effect with tumor-derived IL-6 in immune-compromised hosts.

GSK3 and PKB/Akt are associated with integrin-mediated regulation of PTHrP, IL-6 and IL-8 expression in FG pancreatic cancer cells

We have demonstrated recently that PTHrP is upregulated in pancreatic adenocarcinoma and that the ECM exerts regulatory control, at least in part, over PTHrP expression. In our present study, we examined the potential signaling interactions between these 2 pathways. Our results demonstrate that, under serum-free conditions, adhesion of FG pancreatic adenocarcinoma cells on Fn is mediated by the alpha5beta1 integrin, whereas adhesion to Type I collagen is mediated by the alpha2beta1 integrin. alpha5beta1 integrin-mediated adhesion to Fn results in a phenotype that includes a reduction in cell proliferation, increased E-cadherin localization in cell-cell contacts, increased beta-catenin localization throughout the cell, inhibition of haptokinetic cell migration, and increased expression of PTHrP, IL-6 and IL-8 relative to alpha2beta1 integrin-mediated adhesion on Type I collagen. A phosphoprotein immunoblotting screen of FG pancreatic cancer cells grown on either Fn or Type I collagen indicates that GSK3 and PKB/Akt are differentially phosphorylated on these 2 substrates. These results implicate GSK3 and PKB/Akt in the integrin-mediated regulation of PTHrP, IL-6 and IL-8 in pancreatic cancer.

Pancreatic cancer

Pancreatic cancer remains a major unsolved health problem, with conventional cancer treatments having little impact on disease course. Almost all patients who have pancreatic cancer develop metastases and die. The main risk factors are smoking, age, and some genetic disorders, although the primary causes are poorly understood. Advances in molecular biology have, however, greatly improved understanding of the pathogenesis of pancreatic cancer. Many patients have mutations of the K-ras oncogene, and various tumour-suppressor genes are also inactivated. Growth factors also play an important part. However, disease prognosis is extremely poor. Around 15-20% of patients have resectable disease, but only around 20% of these survive to 5 years. For locally advanced, unresectable, and metastatic disease, treatment is palliative, although fluorouracil chemoradiation for locally advanced and gemcitabine chemotherapy for metastatic disease can provide palliative benefits. Despite pancreatic cancer's resistance to currently available treatments, new methods are being investigated. Preoperative chemoradiation is being advocated, with seemingly sound reasoning, and a wider role for gemcitabine is being explored. However, new therapeutic strategies based on the molecular biology of pancreatic cancer seem to hold the greatest promise.

Activated signal transducer and activator of transcription 3 (STAT3) supports the malignant phenotype of human pancreatic cancer

BACKGROUND & AIMS

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) has been implicated in regulation of growth and malignant transformation. We therefore analyzed the expression and biologic significance of STAT3 in human pancreatic cancer cells.

METHODS

Expression and activation of STAT3 were investigated by immunohistochemistry and immunoblotting. Functional inactivation of STAT3 was achieved by stable transfection of dominant-negative STAT3 constructs in 2 pancreatic cancer cell lines and confirmed by electrophoretic mobility shift assay and immunoblotting. Cell proliferation and tumorigenicity were evaluated by cell counting, colony formation in soft agar, and xenotransplantation in nude mice. STAT3-dependent cell cycle distribution was monitored by flow cytometry, immunoprecipitation, immunoblotting, and histone H1 and GST-Rb kinase assays.

RESULTS

Compared with nontransformed human pancreas, activated STAT3 is overexpressed in ductal carcinoma cells but not in ducts from chronic pancreatitis. Constitutive activation was also observed in all human pancreatic cancer cell lines examined. Functional inactivation of STAT3 resulted in significant inhibition of anchorage-dependent and -independent proliferation in vitro and reduced tumor growth in vivo. Cell cycle analysis showed a delay of G(1)/S-phase progression due to inhibition of cyclin-dependent kinase 2 activity based on increased expression of p21(WAF1) in vitro and in vivo. Blocking of the STAT3 upstream activator Janus kinase 2 by tyrphostin also resulted in growth arrest because of delayed G(1)/S-phase progression and increased expression of p21(WAF1).

CONCLUSIONS

On malignant transformation, activated STAT3 promotes cellular proliferation by acceleration of G(1)/S-phase progression and thereby contributes to the malignant phenotype of human pancreatic cancer.

A critical review of T cell targeting immunotherapy in pancreatic cancer: only a hypothesis or a real hope for the patients?

T cell targeting immunotherapy is now being investigated in patients with pancreatic carcinomas. Until recently this therapeutic strategy has been used as a single specific treatment and clinical studies have demonstrated that tumour-specific T cell responses can be induced in a subset of patients and even in patients with advanced disease. However, it remains to be demonstrated whether these T cell responses can mediate clinically relevant antitumour reactivity. Furthermore, in vitro studies of cancer cell susceptibility to antitumour T cell reactivity are often limited to cancer cell lines because native tumour cells are frequently not available from patients. It is therefore still a hypothesis that T cell targeting immunotherapy can be developed into an efficient therapeutic strategy in patients with inoperable pancreatic cancer. Future investigations of this therapeutic strategy should probably focus on its incorporation into treatment regimens that also include other newer treatment strategies, for example tumour-reactive antibodies coupled with toxins or cytotoxic drugs, improved vaccination procedures probably including the use of dendritic cells and enhancement of antigenic presentation in the tumour microenvironment. T cell targeting immunotherapy will contribute to the hope of curative treatment in patients with inoperable tumours if such combinatory approaches can be developed.

A new liver metastatic and peritoneal dissemination model established from the same human pancreatic cancer cell line: analysis using cDNA macroarray

To elucidate the mechanisms of metastasis, we established two sublines HPC-1H5 with a highly liver metastatic cell line and HPC-1P5a with a highly peritoneal disseminating cell line, which were sequentially selected from the parental pancreatic cancer cell line HPC-1. Using these three cell lines, we investigated several biological properties and mRNA levels of differentially-expressed genes involved in cancer metastasis by cDNA macroarray. Microscopic findings for the three cell lines were the same. The tumorigenicity, in vitro growth ability, motile activity, adhesive activity and the production of IL-8 of metastatic sublines were higher than those of parental HPC-1 cells. Particularly, HPC-1H5 cells showed clearly higher levels of IL-8 expression and tumors of HPC-1H5 cells grew faster and bigger than those of HPC-1P5a cells. In cDNA macroarray analysis of HPC-1H5 cells, 22 genes were up-regulated and 44 genes were down-regulated compared with parental HPC-1 cells. In HPC-1P5a cells, 9 genes were up-regulated and 28 genes were down-regulated compared with parental HPC-1 cells. This study provides a demonstration of global gene expression analysis of pancreatic cancer cells with liver metastasis and peritoneal dissemination. Furthermore, our results provide a new insight into the study of liver metastasis and peritoneal dissemination of human pancreatic cancer.

A novel nude mouse model of liver metastasis and peritoneal dissemination from the same human pancreatic cancer line

INTRODUCTION

Recently, several mice models have been used for investigating cancer metastasis. However, there are no metastatic and peritoneal dominated variants from the same parental cell line.

AIM AND METHODOLOGY

To elucidate the mechanisms of metastasis, we established highly liver metastatic and peritoneal disseminated models in nude mice, and then characterized several factors related to metastasis in these cells. We established a series of well-characterized sublines that showed metastatic potentials to different organ sites of nude mice. Two sublines were selected sequentially from the parental pancreatic cancer cell line, HPC-4, resulting in a highly liver metastatic cell line, HPC-4H4, and a highly peritoneal disseminated cell line, HPC-4P4a. Using these three cell lines, we investigated several biologic properties and mRNA levels of differentially expressed genes involved in cancer metastasis.

RESULTS

The tumorigenicity, the motile activity, and the adhesive activity of metastatic sublines were higher than those of parental HPC-4 cells. Macroscopic and microscopic findings and the DNA ploidy pattern were the same among the three cell lines. In addition, HPC-4H4 cells expressed clearly higher levels of vascular endothelial growth factor and IL-8 expression than did HPC-4P4a cells. In fluorescence-activated cell sorter analysis of adhesion molecules, the expression of integrin-alpha2 was enhanced in HPC-4 cells, integrin-alphavbeta5 was enhanced in HPC-4H4 cells, and integrin-alpha3 was enhanced in HPC-4P4a cells. Osteopontin, vascular endothelial growth factor, and hepatocyte growth factor were among the genes that were upregulated in HPC-4H4 cells compared with HPC-4P4a cells. HPC-4P4a cells did not metastasize to the liver by intrasplenic injection. Conversely, HPC-4H4 cells metastasized remarkably to the peritoneum by intraabdominal injection.

CONCLUSION

These sublines are the first reported liver metastatic and peritoneal disseminated models derived from the same parental cell lines. The results of our study suggest that the process of hematogenous metastasis is not the same as that of peritoneal dissemination.

Mouse models of metastatic pancreatic adenocarcinoma

Pancreatic adenocarcinoma is a deadly disease. Its etiology is unknown, and metastatic disease kills the majority of patients who have it. Effective prevention is clearly the ultimate goal for eradicating this disease provided that the effects of environmental and genetic elements on pancreatic cancer development are fully understood. Currently, it appears that the control of pancreatic cancer metastasis is of immediate urgency. Fulfillment of this difficult task relies on knowledge of the cellular and molecular biology of metastasis. The use of relevant animal models will help define each aspect of this complicated process.

Interleukin-8 and human cancer biology

The aggressive nature of metastatic human cancer has been shown to be related to numerous abnormalities in growth factors and their receptors. These perturbations confer a tremendous growth advantage to the malignant cells. Interleukin-8 (IL-8), originally discovered as a chemotactic factor for leukocytes, has recently been shown to contribute to human cancer progression through its potential functions as a mitogenic, angiogenic, and motogenic factor. While it is constitutively detected in human cancer tissues and established cell lines, IL-8 expression is regulated by various tumor microenvironment factors, such as hypoxia, acidosis, nitric oxide, and cell density. Understanding the mechanisms of both inducible and constitutive IL-8 expression will be helpful in designing potential therapeutic strategies of targeting IL-8 to control tumor growth and metastasis. In this review, the role and regulation of IL-8 expression in the growth and metastasis of human cancer with a focus on human pancreatic adenocarcinoma will be discussed.

Vaccination effect of interleukin-6-producing pancreatic cancer cells in nude mice: a model of tumor prevention and treatment in immune-compromised patients

In an effort to explore properties important in hematogenous metastasis of pancreatic adenocarcinoma, we previously demonstrated that tumor-derived interleukin (IL)-6 is a crucial factor that conveys resistance to liver metastasis. Here we extend the study to examine a possible vaccination effect of tumor-derived IL-6 in T-cell-deficient nude mice, as a model for predicting the effect in immune-compromised patients. We used a pair of IL-6-nonproducing and highly producing pancreatic adenocarcinoma cell lines, PCI-43 and PCI-43h, respectively. The reaction intensity of anti-PCI IgG antibodies in host nude mice was maximal 28 days after inoculation of PCI-43h cells, and remained high thereafter. A fraction of the pancreatic carcinoma cell lines, namely, PCI-6, -10, and -43, expressed surface antigenic determinant(s) reactive with the IgG; but the others, PCI-19, -24, -55, -64, -66, -68, -72, and -79, did not. Inoculation of PCI-43h but not PCI-43 suppressed growth of simultaneously inoculated PCI-43, but not PCI-24 xenografts. In addition, administration of PCI-43h, but not PCI-43 suppressed the growth of PCI-43 that was xenografted 4 weeks later, thus revealing a vaccination effect of IL-6-producing PCI-43h, but not IL-6-nonproducing PCI-43. These data, obtained from T-cell-deficient nude mice, suggest an in vivo role for IL-6 in inducing IgG-mediated, pancreatic carcinoma-specific vaccination against a thymus-independent antigen.

Molecular regulation of constitutive expression of interleukin-8 in human pancreatic adenocarcinoma

Recent studies have shown that interleukin-8 (IL-8) plays an important role in the growth and metastasis of human pancreatic cancer. In the present study, we determined the molecular regulation of constitutive IL-8 expression in human pancreatic cancer cells. Various human pancreatic cancer cell lines were incubated in vitro. Sixty-seven percent of the cell lines constitutively secreted high levels of IL-8, as determined using enzyme-linked immunosorbent assay. Consistently, these cells constitutively expressed high levels of IL-8 mRNA, as determined using Northern blot analysis. To determine the mechanisms of the high steady-state levels of IL-8 mRNA, the IL-8 half-life and transcription rate were measured. There was no significant difference in IL-8 half-life between cells expressing high and low levels of IL-8. However, higher transcription rates and increased IL-8 promoter activity were observed in the cells constitutively expressing high levels of IL-8. Detailed IL-8 promoter analysis using deletion mutation revealed that the region from -85 to -133 bp was essential for the constitutive IL-8 promoter activity. Also, point-mutation analysis indicated that mutation of NF-kappaB, AP-1, or NF-IL-6 binding sites significantly reduced or eliminated the constitutive IL-8 promoter activity. Consistent with the constitutive IL-8 transcription activity, high levels of constitutive NF-kappaB and AP-1 activity were detected in the cells overexpressing IL-8, as determined using electrophoretic mobility shift assay. In addition, transfection of a dominant-negative I-kappaBalpha expression vector (I-kappaBalphaM) inhibited constitutive NF-kappaB activity and IL-8 expression in pancreatic cancer cells. Collectively, our data demonstrated that constitutive NF-kappaB and AP-1 activation contributes to the overexpression of IL-8, which in turn plays an important role in tumor angiogenesis and contributes to the aggressive biology of human pancreatic cancer.

The role of sialylated Lewis antigens on hematogenous metastases of human pancreas carcinoma cell lines in vivo

Previous studies have shown that sialyl Lewis a (SLea) and sialyl Lewis x (SLex) correlated to hematogenous metastasis of human cancers. Although SLea/SLex and E-selectin act as a set of adhesion molecules in vitro, it is not clear whether the in vivo correlation is exclusively mediated by the adhesion function. To address this issue, we investigated whether or not the role of SLea/SLex antigens on hematogenous metastasis to the liver in SCID mice was exclusively mediated by adhesion by using antibodies for these antigens and SLea/SLEx-negative, human pancreas adenocarcinoma cell line PCI-6. The absence of SLea/SLex expression was supported by the absent flow cytometric detection of the antigens as well as by the absent attachment augmentation to activated endothelial cells. PCI-6 cells are xenotransplantable to nude and SCID mice and produce vascular endothelial cell growth factor (VEGF) in a significant amount. PCI-6 cells, 1 x 10(6), were injected into the spleens of SCID mice, and resultant liver metastases were evaluated six weeks later. We observed an inhibitory effect on the establishment and growth of metastatic colonies when anti-SLea or anti-SLex antibody was administered. This indicates that SLea/x antigens have an important in vivo role, even in the metastasis of SLea/SLex-negative tumor cells. This implies that there may be an in vivo function of SLea/x antigens other than that of the attachment between tumor and endothelial cells.

Cooperation between transcription factor AP-1 and NF-kappaB in the induction of interleukin-8 in human pancreatic adenocarcinoma cells by hypoxia

The expression of interleukin-8 (IL-8) has been shown to play an important role in the growth and metastasis of human pancreatic cancer. In the present study, we investigated the regulation of IL-8 gene expression by hypoxic environments. Exposure of the human pancreatic cancer cells COLO357 and FG to hypoxia in culture resulted in a time-dependent increase in steady-state levels of IL-8 mRNA and IL-8 protein secretion. The induction of IL-8 expression was correlated with transcriptional activation of the IL-8 gene. Deletion and point mutation analyses of the IL-8 promoter revealed that both AP-1 and NF-kappaB binding sites were necessary for IL-8 induction by hypoxia. Consistently, hypoxia induced both AP-1 and NF-kappaB activity. These data suggest that hypoxic environments upregulate the IL-8 gene via cooperation of NF-kappaB and AP-1 and contribute to the progression and metastasis of human pancreatic cancer.

Growth factors and cytokines in pancreatic carcinogenesis

Pancreatic cancer is a deadly disease challenging basic and clinical researchers alike in characterizing its pathobiology and finding better treatment options. A number of molecular alterations including gene mutations such as k-ras, p53, and Smad4 and aberrant expression of a variety of genes have been identified in recent years. This review focuses on two families of growth factors and growth factor receptors which are representative for the molecular alterations observed in pancreatic cancer: the transforming growth factor-beta superfamily of serine-threonine kinase receptors and their ligands, which usually act as negative growth regulators, and the epidermal growth factor receptor family and their ligands, which have the potential to act as growth promoters in pancreatic cancer. In addition, we will discuss the role of the cytokines TNF-alpha, IFN-gamma, and IL-6 and its effects on pancreatic cancer cell proliferation in vitro and in vivo. Pancreatic cancer cell biology consists of complex interactions of various factors, and a better understanding of the molecular pathogenesis of this disorder might lead to better treatment strategies in the near future.