Impaired tumorigenicity of human pancreatic cancer cells retrovirally transduced with interleukin-12 or interleukin-15 gene

Mechanisms of obesity- and diabetes mellitus-related pancreatic carcinogenesis: a comprehensive and systematic review

Research on obesity- and diabetes mellitus (DM)-related carcinogenesis has expanded exponentially since these two diseases were recognized as important risk factors for cancers. The growing interest in this area is prominently actuated by the increasing obesity and DM prevalence, which is partially responsible for the slight but constant increase in pancreatic cancer (PC) occurrence. PC is a highly lethal malignancy characterized by its insidious symptoms, delayed diagnosis, and devastating prognosis. The intricate process of obesity and DM promoting pancreatic carcinogenesis involves their local impact on the pancreas and concurrent whole-body systemic changes that are suitable for cancer initiation. The main mechanisms involved in this process include the excessive accumulation of various nutrients and metabolites promoting carcinogenesis directly while also aggravating mutagenic and carcinogenic metabolic disorders by affecting multiple pathways. Detrimental alterations in gastrointestinal and sex hormone levels and microbiome dysfunction further compromise immunometabolic regulation and contribute to the establishment of an immunosuppressive tumor microenvironment (TME) for carcinogenesis, which can be exacerbated by several crucial pathophysiological processes and TME components, such as autophagy, endoplasmic reticulum stress, oxidative stress, epithelial-mesenchymal transition, and exosome secretion. This review provides a comprehensive and critical analysis of the immunometabolic mechanisms of obesity- and DM-related pancreatic carcinogenesis and dissects how metabolic disorders impair anticancer immunity and influence pathophysiological processes to favor cancer initiation.

Chronic Pancreatitis and the Development of Pancreatic Cancer

Pancreatitis is a fibro-inflammatory disorder of the pancreas that can occur acutely or chronically as a result of the activation of digestive enzymes that damage pancreatic cells, which promotes inflammation. Chronic pancreatitis with persistent fibro-inflammation of the pancreas progresses to pancreatic cancer, which is the fourth leading cause of cancer deaths across the globe. Pancreatic cancer involves cross-talk of inflammatory, proliferative, migratory, and fibrotic mechanisms. In this review, we discuss the role of cytokines in the inflammatory cell storm in pancreatitis and pancreatic cancer and their role in the activation of SDF1α/CXCR4, SOCS3, inflammasome, and NF-κB signaling. The aberrant immune reactions contribute to pathological damage of acinar and ductal cells, and the activation of pancreatic stellate cells to a myofibroblast-like phenotype. We summarize several aspects involved in the promotion of pancreatic cancer by inflammation and include a number of regulatory molecules that inhibit that process.

Pancreatic ductal adenocarcinoma immune microenvironment and immunotherapy prospects

The tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) is non-immunogenic, which consists of the stellate cells, fibroblasts, immune cells, extracellular matrix, and some other immune suppressive molecules. This low tumor perfusion microenvironment with physical dense fibrotic stroma shields PDAC from traditional antitumor therapies like chemotherapy and various strategies that have been proven successful in other types of cancer. Immunotherapy has the potential to treat minimal and residual diseases and prevent recurrence with minimal toxicity, and studies in patients with metastatic and nonresectable disease have shown some efficacy. In this review, we highlighted the main components of the pancreatic tumor microenvironment, and meanwhile, summarized the advances of some promising immunotherapies for PDAC, including checkpoint inhibitors, chimeric antigen receptors T cells, and cancer vaccines. Based on our previous researches, we specifically discussed how granulocyte-macrophage colony stimulating factor based pancreatic cancer vaccine prime the pancreatic tumor microenvironment, and introduced some novel immunoadjuvants, like the stimulator of interferon genes.

IL-15 regulates fibrosis and inflammation in a mouse model of chronic pancreatitis

Pancreatitis is an inflammatory disease characterized by the induction of several proinflammatory cytokines like interleukin (IL)-6, IL-8, IL-1β, and IL-1. Recently, the multifunctional innate cytokine IL-15 has been implicated in the protection of several diseases, including cancer. Tissue fibrosis is one of the major problems in successfully treating chronic pancreatitis pathogenesis. Therefore, we tested the hypothesis that recombinant IL-15 (rIL-15) treatment may induce innate tissue responses and its overexpression will improve the pathogenesis of cerulein-induced chronic pancreatitis, associated remodeling, and fibrosis. We observed atrophy of acinar cells, increased inflammation, and increased deposition of perivascular collagen, the upregulated protein level of transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA), and collagen-1 in cerulein-induced chronic pancreatitis in mice. Furthermore, we reported that rIL-15 treatment protects mice from the cerulein-induced chronic pancreatitis pathogenesis, including acinar cell atrophy, and perivascular accumulation of tissue collagen followed by downregulation of profibrotic genes such as TGF-β1, α-SMA, collagen-1, collagen-3, and fibronectin in cerulein-induced chronic pancreatitis in mice. Mechanistically, we show that IL-15-mediated increase of interferon-γ-responsive invariant natural killer T (iNKT) cells in the blood and tissue protects cerulein-induced pancreatic pathogenesis in mice. Of note, a reduction in iNKT cells was also observed in human chronic pancreatitis compared with normal individuals. Taken together, these data suggest that IL-15 treatment may be a novel therapeutic strategy for treating chronic pancreatitis pathogenesis. NEW & NOTEWORTHY Pancreatic fibrosis is a major concern for the successful treatment of chronic pancreatitis and pancreatic cancer. Therefore, restriction in the progression of fibrosis is the promising approach to manage the pancreatitis pathogenesis. Herein, we present in vivo evidences that pharmacological treatment of recombinant interleukin-15 improves remodeling and fibrosis in cerulein-induced chronic pancreatitis in mice. Our observations indicate that interleukin-15 immunotherapy may be a possible and potential strategy for restricting the progression of fibrosis in chronic pancreatitis.

Impact of targeting transforming growth factor β-2 with antisense OT-101 on the cytokine and chemokine profile in patients with advanced pancreatic cancer

Background

Overexpression of the cytokine – transforming growth factor-beta 2 (TGF-β2) – has been implicated in the malignant progression of pancreatic cancer (PAC). OT-101 (trabedersen) is an antisense oligodeoxynucleotide designed to target the human TGF-β2 mRNA. In a Phase I/II study, OT-101 treatment with subsequent chemotherapy was characterized by outstanding overall survival (OS) in patients with PAC.

Objective

This study sought to identify 1) co-regulated sets of cyto-/chemokines; 2) potential mechanisms that link TGF-β receptor type 2 receptor inhibition that may result in the induction of a cytokine storm; and 3) predictive biomarkers for OS outcome in OT-101-treated patients with PAC.

Materials and methods

Plasma levels of 31 cyto-/chemokines were tracked over three cycles of OT-101 therapy (140 mg/m²/day) in 12 PAC patients. Samples were acquired before onset of OT-101 therapy and at eight selected time points during therapy. A mixed ANCOVA model was developed for 19 cyto-/chemokines with median expression >1 following OT-101 therapy. Regression and hierarchical clustering analyses were performed to identify correlated expressions in each patient across cyto-/chemokines or in each cyto-/chemokine across patients. Plasma cyto-/chemokine levels were compared with OS with and without subsequent chemotherapy.

Results

Three highly correlated subsets of cyto-/chemokines (Cluster 1: EGF, MIP-1α, MIP-1β; Cluster 2: FGF-2, MIG, IP-10, IL-15, IFN-α, IL-12; and Cluster 3: HGF, IL-6, IL-8) were identified following OT-101 therapy. Suppression of TGF-β signaling by OT-101 led to upregulation of IL-8, IL-15, IP-10, and HGF. Protein–protein interaction networks constructed using STRING10 algorithm identified a relationship between IL-8, IL-15, and TGF-β receptor type 2 inhibition. The mixed analysis of covariance model that examined the levels of 19 cyto-/chemokines with OS as the covariate at each of the time points resulted in IL-8 and IL-15 exhibiting a significant association with OS during Cycle 1 of therapy. In the whole-blood culture model, the cytokines with the most pronounced increase after OT-101 treatment were IL-1β, IL-8, and MCP-1.

Conclusion

No consistent responses in cyto-/chemokine levels were observed due to OT-101 treatment. Levels of IL-8 and IL-15 during Cycle 1 were positively associated with OS across 12 patients with PAC and served as potential biomarkers for treatment outcome following OT-101 therapy.

Natural killer cells and their therapeutic role in pancreatic cancer: A systematic review

Pancreatic cancer is among the three deadliest cancers worldwide with the lowest 5-year survival of all cancers. Despite all efforts, therapeutic improvements have barely been made over the last decade. Even recent highly promising targeted and immunotherapeutic approaches did not live up to their expectations. Therefore, other horizons have to be explored. Natural Killer (NK) cells are gaining more and more interest as a highly attractive target for cancer immunotherapies, both as pharmaceutical target and for cell therapies. In this systematic review we summarise the pathophysiological adaptions of NK cells in pancreatic cancer and highlight possible (future) therapeutic NK cell-related targets. Furthermore, an extensive overview of recent therapeutic approaches with an effect on NK cells is given, including cytokine-based, viro- and bacteriotherapy and cell therapy. We also discuss ongoing clinical trials that might influence NK cells. In conclusion, although several issues regarding NK cells in pancreatic cancer remain unsolved and need further investigation, extensive evidence is already provided that support NK cell oriented approaches in pancreatic cancer.

Interleukin-15 stimulates natural killer cell-mediated killing of both human pancreatic cancer and stellate cells

Pancreatic ductal adenocarcinoma (PDAC) is the 4^th leading cause of cancer-related death in Western countries with a 5-year survival rate below 5%. One of the hallmarks of this cancer is the strong desmoplastic reaction within the tumor microenvironment (TME), orchestrated by activated pancreatic stellate cells (PSC). This results in a functional and mechanical shield which causes resistance to conventional therapies. Aiming to overcome this resistance by tackling the stromal shield, we assessed for the first time the capacity of IL-15 stimulated natural killer (NK) cells to kill PSC and pancreatic cancer cells (PCC). The potency of IL-15 to promote NK cell-mediated killing was evaluated phenotypically and functionally. In addition, NK cell and immune checkpoint ligands on PSC were charted. We demonstrate that IL-15 activated NK cells kill both PCC and PSC lines (range 9-35% and 20-50%, respectively) in a contact-dependent manner and significantly higher as compared to resting NK cells. Improved killing of these pancreatic cell lines is, at least partly, dependent on IL-15 induced upregulation of TIM-3 and NKG2D. Furthermore, we confirm significant killing of primary PSC by IL-15 activated NK cells in an ex vivo autologous system. Screening for potential targets for immunotherapeutic strategies, we demonstrate surface expression of both inhibitory (PD-L1, PD-L2) and activating (MICA/B, ULBPs and Galectin-9) ligands on primary PSC. These data underscore the therapeutic potential of IL-15 to promote NK cell-mediated cytotoxicity as a treatment of pancreatic cancer and provide promising future targets to tackle remaining PSC.

Targeting tumor tolerance: A new hope for pancreatic cancer therapy?

With a 5-year survival rate of just 8%, pancreatic cancer (PC) is projected to be the second leading cause of cancer deaths by 2030. Most PC patients are not eligible for surgery with curative intent upon diagnosis, emphasizing a need for more effective therapies. However, PC is notoriously resistant to chemoradiation regimens. As an alternative, immune modulating strategies have recently achieved success in melanoma, prompting their application to other solid tumors. For such therapeutic approaches to succeed, a state of immunologic tolerance must be reversed in the tumor microenvironment and that has been especially challenging in PC. Nonetheless, knowledge of the PC immune microenvironment has advanced considerably over the past decade, yielding new insights and perspectives to guide multimodal therapies. In this review, we catalog the historical groundwork and discuss the evolution of the cancer immunology field to its present state with a specific focus on PC. Strategies currently employing immune modulation in PC are reviewed, specifically highlighting 66 clinical trials across the United States and Europe.

Interleukin 23 regulates proliferation of lung cancer cells in a concentration-dependent way in association with the interleukin-23 receptor

A proinflammatory cytokine, interleukin 23 (IL-23), plays a role in tumor progression by inducing inflammation in the tumor microenvironment, although there is debate about its role in carcinogenesis. Direct effects of IL-23 on tumor cells have been reported rarely, and contradictory effects have been observed. Here, we studied such effects of IL-23 in lung cancer cells in vitro and in vivo and explored the underlying mechanism. We found IL-23 receptor expression in tissues from lung adenocarcinoma and small cell carcinoma but not in lung squamous cell carcinoma tissue. Interestingly, different concentrations of IL-23 had opposite effects in the same types of cells. We confirmed that the different effects could be explained by differences in binding to the IL-23 receptor (subunits IL-23r and IL-12Rβ1). Low concentrations of IL-23 promoted the proliferation of IL-23 receptor-positive A549 and SPCA-1 lung cancer cells by binding to IL-23r, whereas high concentrations of IL-23 inhibited proliferation of these cells by binding to both IL-23r and IL-12Rβ1. In contrast, IL-23 had no effect on IL-23 receptor-negative SK-MES-1 cells. IL-23 regulated the growth of human lung cancer cells through its effects on STAT3 expression and phosphorylation in a concentration-dependent way; the Ki-67 gene was involved in these processes. Our findings demonstrate for the first time that IL-23 affects the proliferation of IL-23 receptor-positive lung cancer cells and that this effect is dependent on the IL-23 concentration. This can explain at least part of the inconsistent reports on the role of IL-23 in the progression of carcinogenesis.

Using mice to unveil the genetics of cancer resistance

In the UK, four in ten people will develop some form of cancer during their lifetime, with an individual's relative risk depending on many factors, including age, lifestyle and genetic make-up. Much research has gone into identifying the genes that are mutated in tumorigenesis with the overwhelming majority of genetically-modified (GM) mice in cancer research showing accelerated tumorigenesis or recapitulating key aspects of the tumorigenic process. Yet if six out of ten people will not develop some form of cancer during their lifetime, together with the fact that some cancer patients experience spontaneous regression/remission, it suggests there are ways of 'resisting' cancer. Indeed, there are wildtype, spontaneously-arising mutants and GM mice that show some form of 'resistance' to cancer. Identification of mice with increased resistance to cancer is a novel aspect of cancer research that is important in terms of providing both chemopreventative and therapeutic options. In this review we describe the different mouse lines that display a 'cancer resistance' phenotype and discuss the molecular basis of their resistance.

Cytokine-secreting herpes viral mutants effectively treat tumor in a murine metastatic colorectal liver model by oncolytic and T-cell-dependent mechanisms

In this model of hepatic micrometastases, the antitumor efficacy and role of the T-cell and natural killer (NK) cell populations were studied for oncolytic herpes simplex virus type-1 (HSV-1) viral mutants containing the granulocyte-monocyte colony stimulating factor (GM-CSF (NV1034)) or interluken-12 (IL-12 (NV1042)) cytokine genes. These were compared to saline and control virus (NV1023) in vitro and in vivo. HSV-1 mutants were assessed for cytotoxicity, replication and cytokine expression in CT-26 cells. A syngeneic micrometastatic liver model was then established in naive and immune cell-depleted animals to assess the antitumor efficacy of these viruses. In vitro cytotoxicity and viral replication were similar for each virus, resulting in greater than 80 and 98% cytotoxicity at multiplicity of infection of 1 and 10, respectively. Peak viral titers were 25- to 50-fold higher than initial titer and were not significantly different between viruses. In vivo, all three viruses reduced metastases relative to control, but cytokine-secreting viruses did so with greater efficacy compared to NV1023. This effect was abrogated by T-cell depletion, but not NK-cell depletion. Single-agent therapy with oncolytic viral agents containing GM-CSF or IL-12 is effective in a murine model of liver metastases and likely involves direct viral oncolysis and actions of specific immune effector cells.

Immune enhancement and anti-tumour activity of IL-23

Immunotherapy, including the use of cytokines and/or modified tumour cells immune stimulatory cytokines, can enhance the host anti-tumour immune responses. Interleukin-23 (IL-23) is a relative novel cytokine, which consists of a heterodimer of the IL-12p40 subunit and a novel p19 subunit. IL-23 has biological activities similar to but distinct from IL-12. IL-23 can enhance the proliferation of memory T cells and the production of IFN-gamma, IL-12 and TNF-alpha from activated T cells. IL-23 activates macrophages to produce TNF-alpha and nitric oxide. IL-23 can also act directly on dendritic cells and possesses potent anti-tumour and anti-metastatic activity in murine models of cancer. IL-23 can also induce a lower level of IFN-gamma production compared with that induced by IL-12. This may make IL-23 an alternative and safer therapeutic agent for cancer, as IL-12 administration can lead to severe toxic side effects because of the extremely high levels of IFN-gamma it induces.

Role of inflammation in pancreatic carcinogenesis and the implications for future therapy

BACKGROUND

The link between inflammation and pancreatic cancer has been observed for a number of gastrointestinal neoplasms. This review examines the role of inflammation in pancreatic carcinogenesis and how it can be utilised to develop new therapies against pancreatic cancer.

METHODS

A literature review of Pubmed, Medline and Web of Science databases was undertaken using the key words, pancreatic cancer, inflammation, inducible nitric oxide, interleukins, pro-inflammatory cytokines, cyclooxygenase-2, NF-kappa B, reactive oxygen species, DNA adducts, lipoxygenases, chemoprevention.

RESULTS

Epidemiological evidence and molecular studies both in vitro and in vivo all support the hypothesis that inflammation plays an important in the initiation and progression of pancreatic tumours.

CONCLUSION

Sustained damage caused by chronic inflammation may precede the onset of frank malignancy by a significant interval. As such, suppression of inflammatory changes and oxidative damage, may help delay or even prevent the inception of pancreatic neoplasia.

Transduction of the IL-21 and IL-23 genes in human pancreatic carcinoma cells produces natural killer cell-dependent and -independent antitumor effects

We examined whether novel cytokines, interleukin (IL)-21 and IL-23, that were expressed in tumors could produce antitumor effects in the inoculated mice. Human pancreatic cancer AsPC-1 cells were retrovirally transduced with murine IL-21 or IL-23 (p19-linked p40) gene (AsPC-1/IL-21, AsPC-1/IL-23) and were injected into nude or severe combined immunodeficiency (SCID) mice. Although the proliferation in vitro of the transduced cells remained the same as that of parent cells, growth of AsPC-1/IL-21 and AsPC-1/IL-23 tumors developed in nude mice was retarded compared with that of parent tumors. Treatment of nude mice with anti-asialo GM(1) antibody temporally abrogated the growth retardation of AsPC-1/IL-21, but not AsPC-1/IL-23 tumors; however, the growth of AsPC-1/IL-21 tumors came to be retarded thereafter with the regeneration of natural killer (NK) cells. The growth of AsPC-1/IL-21 tumors developed in SCID mice was also retarded compared with parent tumors and the growth retardation was abrogated by treatment with anti-asialo GM(1) antibody. The growth of AsPC-1/IL-23 tumors in SCID mice was not different from that of parent tumors. Cytotoxic activity and secretion of interferon-gamma in response to AsPC-1 cells were induced in spleen cells of the mice bearing AsPC-1/IL-21 or AsPC-1/IL-23 tumors. When nude mice were injected with a mixed population of AsPC-1/IL-21 and AsPC-1/IL-23 cells, no synergistic effects were observed. These data collectively suggest that expression of IL-21 and IL-23 in tumors can produce NK cell-dependent and -independent antitumor effects in an alpha beta T cell-defective condition, respectively.

Paracrine release of IL-12 stimulates IFN-gamma production and dramatically enhances the antigen-specific T cell response after vaccination with a novel peptide-based cancer vaccine

Interleukin-12 can act as a potent adjuvant for T cell vaccines, but its clinical use is limited by toxicity. Paracrine administration of IL-12 could significantly enhance the response to such vaccines without the toxicity associated with systemic administration. We have developed a novel vaccine delivery system (designated F2 gel matrix) composed of poly-N-acetyl glucosamine that has the dual properties of a sustained-release delivery system and a potent adjuvant. To test the efficacy of paracrine IL-12, we incorporated this cytokine into F2 gel matrix and monitored the response of OT-1 T cells in an adoptive transfer model. Recipient mice were vaccinated with F2 gel/SIINFEKL, F2 gel/SIINFEKL/IL-12 (paracrine IL-12), or F2 gel/SIINFEKL plus systemic IL-12 (systemic IL-12). Systemic levels of IL-12 were lower in paracrine IL-12-treated mice, suggesting that paracrine administration of IL-12 may be associated with less toxicity. However, paracrine administration of IL-12 was associated with an enhanced Ag-specific T cell proliferative and functional response. Furthermore, paracrine IL-12 promoted the generation of a stable, functional memory T cell population and was associated with protection from tumor challenge. To study the mechanisms underlying this enhanced response, wild-type and gene-deficient mice were used. The enhanced immune response was significantly reduced in IFN-gamma(-/-) and IL-12R beta 2(-/-) recipient mice suggesting that the role of IL-12 is mediated, at least in part, by host cells. Collectively, the results support the potential of F2 gel matrix as a vaccine delivery system and suggest that sustained paracrine release of IL-12 has potential clinical application.

Induction of systemic immunity by expression of interleukin-23 in murine colon carcinoma cells

Interleukin-23 (IL-23), a novel cytokine composed of a newly identified p19 molecule and the p40 subunit of IL-12, can stimulate the proliferation in vitro of memory T cells. We examined whether Colon 26 murine colon carcinoma cells that were retrovirally transduced with the p19-linked p40 gene (Colon 26/IL-23) could produce antitumor effects in inoculated mice. The growth of Colon 26/IL-23 tumors developed in immunocompetent mice was significantly retarded and the tumors disappeared thereafter. Spleen cells from the mice that received Colon 26/IL-23 cells produced significant amounts of interferon-gamma, when they were cultured with irradiated Colon 26 but not irrelevant cells. Depletion of CD8(+) T cells suppressed the production of interferon-gamma. The mice that had rejected Colon 26/IL-23 tumors were resistant to subsequent challenge of parent but not irrelevant tumor cells. Colon 26/IL-23 tumors were not rejected in nude mice but the growth was retarded compared to parent tumors. Treatment of nude mice with anti-asialo GM(1) antibody did not influence the growth of Colon 26/IL-23 tumors. These data suggest that expression of IL-23 in tumors produces T cell-dependent antitumor effects and induces systemic immunity.

Expression of the interleukin-21 gene in murine colon carcinoma cells generates systemic immunity in the inoculated hosts

Interleukin-21 (IL-21) is a novel cytokine that can induce proliferation of activated T cells and maturation of natural killer (NK) cells. We therefore examined whether expression of the IL-21 gene in tumor cells could generate antitumor responses. Murine colon carcinoma Colon 26 cells that were transduced with the mouse IL-21 gene (Colon 26/IL-21) were rejected in syngeneic mice and the mice subsequently acquired protective immunity. The growth of Colon 26/IL-21 tumors developed in nude mice was retarded compared with that of parent tumors, and this growth suppression was not observed in nude mice that were treated with anti-asialo GM(1) antibody. Spleen cells from the mice that had rejected Colon 26/IL-21 cells showed cytotoxic activity to Colon 26 but not to irrelevant tumor cells, and produced larger amounts of interferon-gamma upon stimulation with irradiated Colon 26 cells. Spleen cells from Colon 26/IL-21-tumor- but not parent-tumor-bearing mice had lytic activity to YAC-1 cells. These data suggest that expression of IL-21 in tumors induces T- and NK-cell-dependent antitumor effects.

Gene therapy for pancreatic cancer

Gene transfer technology has the potential to revolutionize cancer treatment. Developments in molecular biology, genetics, genomics, stem cell technology, virology, bioengineering, and immunology are accelerating the pace of innovation and movement from the laboratory bench to the clinical arena. Pancreatic adenocarcinoma, with its particularly poor prognosis and lack of effective traditional therapy for most patients, is an area where gene transfer and immunotherapy have a maximal opportunity to demonstrate efficacy. In this review, we have discussed current preclinical and clinical investigation of gene transfer technology for pancreatic cancer. We have emphasized that the many strategies under investigation for cancer gene therapy can be classified into two major categories. The first category of therapies rely on the transduction of cells other than tumor cells, or the limited transduction of tumor tissue. These therapies, which do not require efficient gene transfer, generally lead to systemic biological effects (e.g., systemic antitumor immunity, inhibition of tumor angiogenesis, etc) and therefore the effects of limited gene transfer are biologically "amplified." The second category of gene transfer strategies requires the delivery of therapeutic genetic material to all or most tumor cells. While these elegant approaches are based on state-of-the-art advances in our understanding of the molecular biology of cancer, they suffer from the current inadequacies of gene transfer technology. At least in the short term, it is very likely that success in pancreatic cancer gene therapy will involve therapies that require only the limited transduction of cells. The time-worn surgical maxim, "Do what's easy first," certainly applies here.

Inflammation and the development of pancreatic cancer

OBJECTIVE

Pancreatic cancer has an extremely poor prognosis and the cellular mechanisms contributing to pancreatic cancer are relatively unknown. The goals of this review are to present the epidemiological and experimental data that supports inflammation as a key mediator of pancreatic cancer development, to explain how inflammatory pathways may create an environment that supports tumor formation, and to discuss how the use of novel agents directed at these pathways may be used for the treatment of pancreatic malignancy.

SUMMARY BACKGROUND DATA

Inflammation has been identified as a significant factor in the development of other solid tumor malignancies. Both hereditary and sporadic forms of chronic pancreatitis are associated with an increased risk of developing pancreatic cancer. The combined increase in genomic damage and cellular proliferation, both of which are seen with inflammation, strongly favors malignant transformation of pancreatic cells. Cytokines, reactive oxygen species, and mediators of the inflammatory pathway (e.g., NF-kappaB and COX-2) have been shown to increase cell cycling, cause loss of tumor suppressor function, and stimulate oncogene expression; all of which may lead to pancreatic malignancy. Anti-cytokine vaccines, inhibitors of pro-inflammatory NF-kappaB and COX-2 pathways, thiazolidinediones, and anti-oxidants are potentially useful for the prevention or treatment of pancreatic cancer. Redirection of experimental interests toward pancreatic inflammation and mechanisms of carcinogenesis may identify other novel anti-inflammatory agents or other ways to screen for or prevent pancreatic cancer.

CONCLUSION

Pancreatic inflammation, mediated by cytokines, reactive oxygen species, and upregulated pro-inflammatory pathways, may play a key role in the early development of pancreatic malignancy.

Immunotherapy for pancreatic cancer: current concepts

Despite advances in chemotherapy and surgical technique, patients with pancreatic cancer often succumb to local recurrence or metastatic spread. The need for new therapeutic strategies for this disease coupled with a better understanding of basic immunology have led to the development of novel anti-tumor vaccines. This review focuses on the historical development of tumor vaccines emphasizing the identification of potential pancreatic tumor antigens. The role of both B-cell and T-cell responses in tumor rejection will be reviewed. Methods for antigen presentation, including peptides, recombinant viral and bacterial vectors, dendritic cells, and whole cell approaches will be discussed. The use of immune adjuvants and improved methods of vaccine delivery will also be explored. The full potential for the immunotherapy of pancreatic cancer awaits the results of early phase clinical trials. The development of pancreatic cancer vaccines represents a useful paradigm for the translation of basic research into the clinical arena.

In vivo electroporation-mediated transfer of interleukin-12 and interleukin-18 genes induces significant antitumor effects against melanoma in mice

Direct intratumoral transfection of cytokine genes was performed by means of the in vivo electroporation as a novel therapeutic strategy for cancer. Plasmid vectors carrying the firefly luciferase, interleukin (IL)-12 and IL-18 genes were injected into established subcutaneous B16-derived melanomas followed by electric pulsation. When plasmid vectors with Epstein--Barr virus (EBV) nuclear antigen 1 (EBNA1) gene were employed, the expression levels of the transgenes were significantly higher in comparison with those obtained with conventional plasmid vectors. In consequence of the transfection with IL-12 and IL-18 genes, serum concentrations of the cytokines were significantly elevated, while interferon (IFN)-gamma also increased in the sera of the animals. The IL-12 gene transfection resulted in significant suppression of tumor growth, while the therapeutic effect was further improved by co-transfection with IL-12 and IL-18 genes. Repetitive co-transfection with IL-12 and IL-18 genes resulted in significant prolongation of survival of the animals. Natural killer (NK) and cytotoxic T lymphocyte (CTL) activities were markedly enhanced in the mice transfected with the cytokine genes. The present data suggest that the cytokine gene transfer can be successfully achieved by in vivo electroporation, leading to both specific and nonspecific antitumoral immune responses and significant therapeutic outcome.

Innovative treatments for pancreatic cancer

Pancreatic cancer is the fifth leading cause of cancer deaths in the United States with little or no impact from conventional treatment options. Significant advances in understanding basic immunology have renewed interest in using immunotherapy to treat pancreatic cancer. Cancer immunotherapy, including humanized MAbs, cytokines, and potent vaccine strategies, has been successful in animal models and is being evaluated in clinical trials. Gene therapy is also being explored using methods to inactivate oncogenes, replace defective tumor suppressor genes, confer enhanced chemosensitivity to tumor cells, and increase immunogenicity of tumor cells. Angiogenesis, an essential step in the growth and metastasis of pancreatic cancer, has been targeted by many antiangiogenic agents. Several clinical trials have been initiated to evaluate the role of these innovative strategies in patients with pancreatic cancer with increasingly sophisticated correlative studies to learn more about the mechanisms of tumor rejection with these agents. The rapid translation of basic science discoveries to clinical trials should result in the development of new effective treatments for patients with pancreatic cancer.