Suicide gene therapy with HSV-TK in pancreatic cancer has no effect in vivo in a mouse model

New avenues for the treatment of immunotherapy-resistant pancreatic cancer

Pancreatic cancer (PC) is characterized by its extremely aggressive nature and ranks 14th in the number of new cancer cases worldwide. However, due to its complexity, it ranks 7th in the list of the most lethal cancers worldwide. The pathogenesis of PC involves several complex processes, including familial genetic factors associated with risk factors such as obesity, diabetes mellitus, chronic pancreatitis, and smoking. Mutations in genes such as KRAS, TP53, and SMAD4 are linked to the appearance of malignant cells that generate pancreatic lesions and, consequently, cancer. In this context, some therapies are used for PC, one of which is immunotherapy, which is extremely promising in various other types of cancer but has shown little response in the treatment of PC due to various resistance mechanisms that contribute to a drop in immunotherapy efficiency. It is therefore clear that the tumor microenvironment (TME) has a huge impact on the resistance process, since cellular and non-cellular elements create an immunosuppressive environment, characterized by a dense desmoplastic stroma with cancer-associated fibroblasts, pancreatic stellate cells, extracellular matrix, and immunosuppressive cells. Linked to this are genetic mutations in TP53 and immunosuppressive factors that act on T cells, resulting in a shortage of CD8+ T cells and limited expression of activation markers such as interferon-gamma. In this way, finding new strategies that make it possible to manipulate resistance mechanisms is necessary. Thus, techniques such as the use of TME modulators that block receptors and stromal molecules that generate resistance, the use of genetic manipulation in specific regions, such as microRNAs, the modulation of extrinsic and intrinsic factors associated with T cells, and, above all, therapeutic models that combine these modulation techniques constitute the promising future of PC therapy. Thus, this study aims to elucidate the main mechanisms of resistance to immunotherapy in PC and new ways of manipulating this process, resulting in a more efficient therapy for cancer patients and, consequently, a reduction in the lethality of this aggressive cancer.

Suicide gene therapy in cancer and HIV-1 infection: An alternative to conventional treatments

Suicide Gene Therapy (SGT) aims to introduce a gene encoding either a toxin or an enzyme making the targeted cell more sensitive to chemotherapy. SGT represents an alternative approach to combat pathologies where conventional treatments fail such as pancreatic cancer or the high-grade glioblastoma which are still desperately lethal. We review the possibility to use SGT to treat these cancers which have shown promising results in vitro and in preclinical trials. However, SGT has so far failed in phase III clinical trials thus further improvements are awaited. We can now take advantages of the many advances made in SGT for treating cancer to combat other pathologies such as HIV-1 infection. In the review we also discuss the feasibility to add SGT to the therapeutic arsenal used to cure HIV-1-infected patients. Indeed, preliminary results suggest that both productive and latently infected cells are targeted by the SGT. In the last section, we address the limitations of this approach and how we might improve it.

Room for improvement in the treatment of pancreatic cancer: Novel opportunities from gene targeted therapy

Pancreatic cancer is one of the highest and in fact, unchanged mortality-associated tumor, with an exceptionally low survival rate due to its challenging diagnostic approach. So far, its treatment is based on a combination of approaches (such as surgical resection with or rarely without chemotherapeutic agents), but with finite limits. Thus, looking for additional space to improve pancreatic tumorigenesis therapeutic approach, research has focused on gene therapy with unexpectedly growing horizons not only for the treatment of inoperable pancreatic disease, but also for its early stages. In vivo gene delivery viral vectors, despite few disadvantages (possible immunogenicity, toxicity, mutagenicity, or high cost), could be one of the most efficient cancer gene therapeutic strategies for clinical application due to their superiority compared with other systems (ex vivo delivery strategies). Their dominance consists of simple preparation, easy operation and a wide range of functions. Adenoviruses are one of the most common used vectors, inducing strong immune as well as inflammatory reactions. Oncolytic virotherapy, using the above mentioned in vivo viral vectors, is one of the most promising non-pathogenic, highly-selective cytotoxic anti-cancer therapy using anti-cancer agents with high anti-tumor potency and strong oncolytic effect. There have been a variety of targeted therapeutic and pre-clinical strategies tested for gene therapy in pancreatic cancer such as gene-editing systems (e.g., clustered regularly interspaced palindromic repeats-Cas9), RNA interference technology (e.g., microRNAs, short hairpin RNA or small interfering RNA), adoptive immunotherapy and vaccination (e.g., chimeric antigen receptor T-cell therapy) with encouraging results.

Progress in Animal Models of Pancreatic Ductal Adenocarcinoma

As a common gastrointestinal tumor, the incidence of pancreatic cancer has been increasing in recent years. The disease shows multi-gene, multi-step complex evolution from occurrence to dissemination. Furthermore, pancreatic cancer has an insidious onset and an extremely poor prognosis, so it is difficult to obtain cinical specimens at different stages of the disease, and it is, therefore, difficult to observe tumorigenesis and tumor development in patients with pancreatic cancer. At present, no standard protocols stipulate clinical treatment of pancreatic cancer, and the benefit rate of new targeted therapies is low. For this reason, a well-established preclinical model of pancreatic cancer must be established to allow further exploration of the occurrence, development, invasion, and metastasis mechanism of pancreatic cancer, as well as to facilitate research into new therapeutic targets. A large number of animal models of pancreatic cancer are currently available, including a cancer cell line-based xenograft, a patient-derived xenograft, several mouse models (including transgenic mice), and organoid models. These models have their own characteristics, but they still cannot perfectly predict the clinical outcome of the new treatment. In this paper, we present the distinctive features of the currently popular pancreatic cancer models, and discuss their preparation methods, clinical relations, scientific purposes and limitations.

Golgi membrane protein GP73 modified-liposome mediates the antitumor effect of survivin promoter-driven HSVtk in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common types of cancer worldwide, and there is currently no effective therapeutic strategy in clinical practice. Gene therapy has great potential for decreasing tumor-induced mortality but has been clinically limited because of the lack of tumor-specific targets and insufficient gene transfer. The study of targeted transport of therapeutic genes in HCC treatment seems to be very important. In this study, we evaluated a gene therapy approach targeting HCC using the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system in HCC cell lines and in an in vivo human HCC xenograft mouse model. GP73-modified liposomes targeted gene delivery to the tumor tissue, and the survivin promoter drove HSVtk expression in the HCC cells. Our results showed that the survivin promoter was specifically activated in tumor cells and HSVtk was expressed selectively in tumor cells. Combined with GCV treatment, HSVtk expression resulted in suppression of HCC cell proliferation via enhancing apoptosis. Moreover, tail vein injection of GP73-HSVtk significantly suppressed the growth of xenograft tumors through an apoptosis-dependent pathway and extended the survival of tumor-bearing mice without damaging the mice liver functions. Taken together, this study demonstrates an effective cancer-specific gene therapy strategy using the herpes simplex virus thymidine kinase/ganciclovir (HSVtk/GCV) suicide gene system for HCC that can be further developed for future clinical trials.

Targeted gene therapy of the HSV-TK/hIL-12 fusion gene controlled by the hSLPI gene promoter of human non-small cell lung cancer in vitro

The incidence of lung cancer and lung cancer-associated mortality have markedly increased worldwide, and gene-targeted therapy has emerged as a promising treatment strategy. The present study aimed to explore the targeted antitumor effect of the herpes simplex virus-thymidine kinase/human interleukin-12 (HSV-TK/hIL-12) fusion gene regulated by the human secretory leukocyte protease inhibitor (hSLPI) promoter of human non-small cell lung cancer (hNSCLC). There were four recombinant eukaryotic expression vectors: pcDNA3.1-CMV-TK, pcDNA3.1-CMV-TK/hIL-12, pcDNA3.1-phSLP-TK and pcDNA3.1-phSLP-TK/hIL-12. These were constructed and transfected into the A549, SPC-A1 and HepG2 cell lines in vitro. The expression of the HSV-TK/hIL-12 fusion gene was detected with reverse transcription-polymerase chain reaction (RT-PCR), and the content of hIL-12 was measured using an ELISA. The antitumor effect of the fusion gene on the A549, SPC-A1 and HepG2 cell lines was determined using an MTT assay. Analysis of the experimental data demonstrated that genes regulated by the cytomegalovirus promoter were expressed at the same level in three different tumor cell lines. Genes regulated by the hSLPI promoter were expressed in the A549 and SPC-A1 cell lines, but not in the HepG2 cell line. Coincidentally, the hIL-12 expression levels were similar to those observed in previous RT-PCR findings. In the Pcmv-TK/Pcmv-TK-hIL-12 group for all three cell lines, as well as in the PSLPI-TK/PSLPI-TK-hIL-12 group for the A549 and SPC-A1 cell lines, the cell survival rate declined significantly and the fusion gene transfection group indicated a lower cell survival rate, when compared with single gene transfection group. The present study indicated that the fusion gene regulated by the hSLPI promoter had a targeted antitumor effect on hNSCLC, and that the combined suicide gene and immune gene therapy had a stronger antitumor effect, compared with single gene therapy.

Phospho-valproic acid inhibits pancreatic cancer growth in mice: enhanced efficacy by its formulation in poly-(L)-lactic acid-poly(ethylene glycol) nanoparticles

Pancreatic cancer (PC) is one of the most difficult cancers to treat. Since the current chemotherapy is inadequate and various biological approaches have failed, the need for agents that have a potential to treat PC is pressing. Phosphovalproic acid (P-V), a novel anticancer agent, is efficacious in xenograft models of human PC and is apparently safe. In the present study, we evaluated whether formulating P-V in nanoparticles could enhance its anticancer efficacy. In a mouse model of Kras/pancreatitis-associated PC, P-V, orally administered, inhibited the incidence of acinar-to-ductal metaplasia by 60%. To improve its efficacy, we formulated P-V in five different polymeric nanoparticles. Poly-(L)-lactic acid-poly(ethylene glycol) (PLLA-PEG) nanoparticles proved the optimal formulation. PLLA-PEG improved P-V's pharmacokinetics in mice enhancing the levels of P-V in blood. Compared to control, P-V formulated in PLLA-PEG suppressed the growth of MIA PaCa-2 xenografts by 81%, whereas P-V alone reduced it by 51% (P<0.01). Furthermore, P-V formulated in PLLA-PEG inhibited acinar-to-ductal metaplasia in mice with activated Kras, reducing it by 87% (P<0.02). In both disease models, P-V suppressed STAT3 phosphorylation at the Ser727 and Tyr705 residues; STAT3 is the pivotal molecular target of P-V. In conclusion, P-V is a promising agent against PC, and its formulation in PLLA-PEG nanoparticles enhances its efficacy by improving its pharmacokinetics.

Gene Therapy for Pancreatic Cancer: Specificity, Issues and Hopes

A recent death projection has placed pancreatic ductal adenocarcinoma as the second cause of death by cancer in 2030. The prognosis for pancreatic cancer is very poor and there is a great need for new treatments that can change this poor outcome. Developments of therapeutic innovations in combination with conventional chemotherapy are needed urgently. Among innovative treatments the gene therapy offers a promising avenue. The present review gives an overview of the general strategy of gene therapy as well as the limitations and stakes of the different experimental in vivo models, expression vectors (synthetic and viral), molecular tools (interference RNA, genome editing) and therapeutic genes (tumor suppressor genes, antiangiogenic and pro-apoptotic genes, suicide genes). The latest developments in pancreatic carcinoma gene therapy are described including gene-based tumor cell sensitization to chemotherapy, vaccination and adoptive immunotherapy (chimeric antigen receptor T-cells strategy). Nowadays, there is a specific development of oncolytic virus therapies including oncolytic adenoviruses, herpes virus, parvovirus or reovirus. A summary of all published and on-going phase-1 trials is given. Most of them associate gene therapy and chemotherapy or radiochemotherapy. The first results are encouraging for most of the trials but remain to be confirmed in phase 2 trials.

The small heat shock protein αA-crystallin negatively regulates pancreatic tumorigenesis

Our recent study has shown that αA-crystallin appears to act as a tumor suppressor in pancreas. Here, we analyzed expression patterns of αA-crystallin in the pancreatic tumor tissue and the neighbor normal tissue from 74 pancreatic cancer patients and also pancreatic cancer cell lines. Immunocytochemistry revealed that αA-crystallin was highly expressed in the normal tissue from 56 patients, but barely detectable in the pancreatic tumor tissue. Moreover, a low level of αA-crystallin predicts poor prognosis for patients with pancreatic duct adenocarcinoma (PDAC). In the 12 pancreatic cell lines analyzed, except for Capan-1 and Miapaca-2 where the level of αA-crystallin was about 80% and 65% of that in the control cell line, HPNE, the remaining pancreatic cancer cells have much lower αA-crystallin levels. Overexpression of αA-crystallin in MiaPaca-1 cells lacking endogenous αA-crystallin significantly decreased its tumorigenicity ability as shown in the colony formation and wound healing assays. In contrast, knockdown of αA-crystallin in the Capan-1 cells significantly increased its tumorigenicity ability as demonstrated in the above assays. Together, our results further demonstrate that αA-crystallin negatively regulates pancreatic tumorigenesis and appears to be a prognosis biomarker for PDAC.

Killing Effect of the Herpes Simplex Virus Thymidine Kinase/Ganciclovir Enzyme/Prodrug System on Human Nasopharyngeal Carcinoma Cells

A promising new approach for the gene therapy of cancer is the introduction of the herpes simplex virus thymidine kinase (HSV tk) gene into tumour cells, where the HSV tk gene product converts the non-toxic prodrug ganciclovir (GCV) into its cytotoxic metabolite. We constructed a recombinant plasmid containing the HSV tk gene using standard molecular biology techniques in order to investigate whether the HSV tk/GCV enzyme/prodrug system could kill the human nasopharyngeal carcinoma cell line HNE-1. The recombinant plasmid pcDNA3.1(–) CMV.TK was transfected into the HNE-1 cells by electroporation. The expression of HSV tk by the transfected HNE-1/TK cells was confirmed by mRNA amplification and Western blotting. The growth of HNE-1/TK cells was inhibited by GCV in a dose-dependent manner. The HSV tk/GCV system also demonstrated a considerable bystander effect on co-cultured wild type HNE-1 cells. We conclude that the HSV tk/GCV system could be used as gene therapy for nasopharyngeal carcinoma.

Gene therapy in pancreatic cancer

Pancreatic cancer (PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC. This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website (http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property. Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras, anti-angiogenesis gene VEGFR, suicide gene HSK-TK, cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiotherapy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.

Pancreatic cancer: gene therapy approaches and gene delivery systems

IMPORTANCE OF THE FIELD

Due to the absence of early diagnosis, the highly invasive and metastatic features and the lack of effective therapeutic modalities, the prognosis of patients with pancreatic cancer is poor. Gene therapy is currently regarded as a potential and promising therapeutic modality for pancreatic cancer.

AREAS COVERED IN THIS REVIEW

This article summarizes an update of gene therapy approaches and reviews the latest progress in gene delivery systems that have been tested on pancreatic cancer.

WHAT THE READER WILL GAIN

The treatment effectiveness of gene combination therapy is better than that of the regulation of single-gene or single gene therapy approaches. Naked DNA is limited because of degradation by intracellular and extracellular nucleases. Virus vectors show high transfection efficiency but are limited due to immunogenicity, inflammatory response and potential carcinogenicity. Non-viral vectors, such as cationic polymers or inorganic nanoparticles, show an important feature that they can be easily modified, and the progress of materials science will provide more and better non-viral vectors, accordingly improving the efficiency and safety of gene therapy, which will make them the most promising vectors for pancreatic cancer.

Phenotype and genotype of pancreatic cancer cell lines

The dismal prognosis of pancreatic adenocarcinoma is due in part to a lack of molecular information regarding disease development. Established cell lines remain a useful tool for investigating these molecular events. Here we present a review of available information on commonly used pancreatic adenocarcinoma cell lines as a resource to help investigators select the cell lines most appropriate for their particular research needs. Information on clinical history; in vitro and in vivo growth characteristics; phenotypic characteristics, such as adhesion, invasion, migration, and tumorigenesis; and genotypic status of commonly altered genes (KRAS, p53, p16, and SMAD4) was evaluated. Identification of both consensus and discrepant information in the literature suggests careful evaluation before selection of cell lines and attention be given to cell line authentication.

The development of gene therapy: from monogenic recessive disorders to complex diseases such as cancer

During the last 4 decades, gene therapy has moved from preclinical to clinical studies for many diseases ranging from monogenic recessive disorders such as hemophilia to more complex diseases such as cancer, cardiovascular disorders, and human immunodeficiency virus (HIV). To date, more than 1,340 gene therapy clinical trials have been completed, are ongoing, or have been approved in 28 countries, using more than 100 genes. Most of those clinical trials (66.5%) were aimed at the treatment of cancer. Early hype, failures, and tragic events have now largely been replaced by the necessary stepwise progress needed to realize clinical benefits. We now understand better the strengths and weaknesses of various gene transfer vectors; this facilitates the choice of appropriate vectors for individual diseases. Continuous advances in our understanding of tumor biology have allowed the development of elegant, more efficient, and less toxic treatment strategies. In this introductory chapter, we review the history of gene therapy since the early 1960s and present in detail two major recurring themes in gene therapy: (1) the development of vector and delivery systems and (2) the design of strategies to fight or cure particular diseases. The field of cancer gene therapy experienced an "awkward adolescence." Although this field has certainly not yet reached maturity, it still holds the potential of alleviating the suffering of many individuals with cancer.

Biological approaches to therapy of pancreatic cancer

Pancreatic cancer is a lethal disease and notoriously difficult to treat. Only a small proportion is curative by surgical resection, whilst standard chemotherapy for patients with advanced disease has only modest effect with substantial toxicity. Clearly there is a need for the continual development of novel therapeutic agents to improve the current situation. Improvement of our understanding of the disease has generated a large number of studies on biological approaches targeting the molecular abnormalities of pancreatic cancer, including gene therapy and signal transduction inhibition, antiangiogenic and matrix metalloproteinase inhibition, oncolytic viral therapy and immunotherapy. This article provides a review of these approaches, both investigated in the laboratories and in subsequent clinical trials.

Antimetastatic effect of suicide gene therapy for mouse mammary cancers requires T-cell-mediated immune responses

These experiments were conducted to investigate whether the antimetastatic effects of HSVtk/GCV therapy involve T-cell-mediated immune responses. In the first experiment, immunocompetent syngeneic mice were inoculated with metastatic mammary cancers, then given a direct intratumoral injection of a plasmid vector containing a suicide gene (pHSVtk) or control vector once a week for 8 weeks. Gene electrotransfer treatment was applied to the tumors, and mice were administered ganciclovir (GCV) using a mini-osmotic pump. At the end of the experiment, tumor volume was significantly lower in the pHSVtk/GCV group. Macrophage accumulations were frequently observed in the peripheries of the necrotic regions in pHSVtk-transfected mice. Levels of CD4 and CD8 proteins in tumors were higher in the pHSVtk/GCV group than in the control group. Interleukin (IL)-12 mRNA levels tended to be higher in tumors in the pHSVtk/GCV group, but there were large variations. Tumor microvessel density was significantly lower in the pHSVtk/GCV group. The numbers of dilated lymphatic vessels containing intraluminal tumor cells tended to be higher in the pHSVtk/GCV group. However, vascular endothelial growth factor (VEGF)-A and VEGF-C mRNA levels in tumors were similar in the control and pHSVtk/GCV groups. In the second experiment, tumor volume and metastatic parameters were compared for immunocompetent syngeneic mice and immunodeficient athymic mice (without an intact T-cell system) given pHSVtk/GCV therapy. Although tumor volumes were significantly smaller in both syngeneic and athymic mice given pHSVtk/GCV therapy, the inhibition ratios (relative to control mice) were much greater in syngeneic mice than in athymic mice. No suppression of metastasis to the lymph nodes and lungs was observed for athymic mice given pHSVtk/GCV therapy. Our data suggest that HSVtk/GCV suicide gene therapy exerts an antimetastatic effect via a T-cell-mediated immune response.

Suicide gene therapy with the yeast fusion gene cytosine deaminase/uracil phosphoribosyltransferase is not enough for pancreatic cancer

OBJECTIVES

Suicide gene therapy with FCY1 gene, encoding cytosine deaminase (CD), together with FUR1, encoding uracil phosphoribosyltransferase (UPRT), has been proposed for pancreatic cancer therapy in vivo. We ascertained whether gene therapy with FCY1-FUR1 is effective in killing pancreatic cancer cells after 5-fluorocytosine (5-FC) treatment.

METHODS

AsPC1, BxPC3, Capan1, MIA PaCa2, and Panc1 cell lines were transfected using 2 plasmid vectors expressing CD only (pRSV-CD) or the chimera CD-UPRT (pRSV-CD-UPRT). Control and pRSV-CD- or pRSV-CD-UPRT-transfected cell lines were treated with 0, 0.1, 0.5, 1, 5, and 10 mM of 5-FC for 1, 3, 6, 8, 10, and 13 days.

RESULTS

FCY1 alone did not confer sensitivity to 5-FC. The CD-UPRT-transfected BxPC3 and Panc1 were sensitive to very low 5-FC doses (0.1 mM). 5-Fluorocytosine-sensitive transfected cell lines rapidly converted 5-FC into 5-fluorouracil, whereas the 5-FC resistant cell lines had an impaired 5-FC conversion.

CONCLUSIONS

Suicide gene therapy with the FCY1 gene alone was ineffective in the treatment of pancreatic cancer in vitro. The pRSV-CD-UPRT construct conferred 5-FC sensitivity to some pancreatic cancer cell lines. Therefore, the application in vivo of suicide gene therapy with FCY1 alone or in combination with the FUR1 gene is probably destined to fail.

Enhanced Cytotoxicity of RIPTK Gene Therapy of Pancreatic Cancer via PDX-1 Co-Delivery

BACKGROUND

Using in vivo mouse models, we have demonstrated that the insulin promoter-driven suicidal gene therapy (RIPTK) could be used in the treatment of mouse insulinoma and human pancreatic cancer cells. However, limitations of this therapy include tumor cells lack of sufficient PDX-1 protein and low levels of transgene expression mediated by liposome delivery system. The purpose of this study was to determine 1) whether transient transfection of PDX-1 into selected pancreatic cancer cells would lead to increased RIPTK cytotoxicity, and 2) whether an adenoviral delivery system would increase the overall RIPTK gene expression in vitro.

MATERIAL AND METHODS

RIPlacZ and RSVlacZ plasmid DNA as well as AdCMVlacZ and AdRIPlacZ were used in transfection assays in human pancreatic cancer cell lines PANC-1 and MIA PaCa2 (n = 8). An expression plasmid DNA containing the mouse PDX-1 cDNA was also used. LacZ reporter assays were performed. RIPTK genes constructed either in plasmid or in adenoviral vectors were used in cytotoxic assays. RT-PCR assays were used to determine PDX-1 expression levels.

RESULTS

PDX-1 protein was detected in the human pancreatic ductal carcinoma cell line PANC-1, a little in MIA PaCa2 cells. Liposome mediated (L) RSVlacZ and RIPlacZ transfection in PANC-1 cells resulted in 10.1% and 9.3% transgene expression, respectively. Co-delivery of PDX-1 had no significant effect on RSVlacZ expression (9.3%, P = NS) but significantly increased RIPlacZ gene expression (14.9% P < 0.05). Adenoviral mediated (Ad) RIPlacZ transgene was highly expressed in PANC-1 cells (66.1%) and the reporter activity was further enhanced when PDX-1 was co-delivered (70.2%, P < 0.05). Liposomal transfection of MIA PaCa2 cells using RSVlacZ and RIPlacZ reporter genes resulted in 9.3% and 1.0% gene expression, respectively. Co-transfection of PDX-1 in these cells resulted in a significant activation of RIPlacZ gene expression (14.5%, P < 0.05) with no effects on RSVlacZ treated cells (9.8%). AdCMVlacZ and AdRIPlacZ significantly increased reporter activities in MIA PaCa2 cells (63.0% and 9.8%, respectively). Transfection of PDX-1 also significantly enhanced the AdRIPlacZ activities (46.0%, P < 0.05), with no significant effect in AdCMVlacZ treated cells (68.2%). The cytotoxic effect of liposome-RIPTK/ganciclovir (GCV) in PANC-1 cells was 18.6% and increased to 22.8% when PDX-1 was co-transfected into the cells (P = NS). MIA PaCa2 cells treated with RIPTK alone resulted in 4.9% cell death and increased to 18.2% when exogenous PDX-1 was co-delivered (P < 0.05). The AdRIPTK gene delivery with GCV treatment caused significant cytotoxic effect in PANC-1 (29.3%) and MIA PaCa2 (12.4%) compared with untreated cells. The cytotoxic effects were further increased to 43.4% and 29.4% in PANC-1 and MIA PaCa2 cells, respectively, when PDX-1 was co-transfected (P < 0.05 for both).

CONCLUSIONS

These data demonstrated that adenoviral mediated gene delivery resulted in a significant increase of transgene expression compared with liposomal delivery systems. RIPTK mediated cytotoxicity was also significantly enhanced via co-delivery of exogenous PDX-1 in these cells. Thus, these results also indicated that PDX-1 plays critical roles in insulin promoter activation and demonstrated that PDX-1 production is essential for insulin promoter-directed gene therapy.

Pancreatic cancer cells invasiveness is mainly affected by interleukin-1beta not by transforming growth factor-beta1

BACKGROUND

We investigated in vitro whether IL-1beta and TGF-beta1 affect pancreatic cancer cell growth, adhesion to the extracellular matrix and Matrigel invasion.

MATERIALS AND METHODS

Adhesion to fibronectin, laminin and type I collagen, and Matrigel invasion after stimulation with saline, IL-1beta and TGF-beta1 were evaluated using three primary and three metastatic pancreatic cancer cell lines.

RESULTS

Extracellular matrix adhesion of control cells varied independently of the metastatic characteristics of the studied cell lines, whereas Matrigel invasion of control cells was partly correlated with the in vivo metastatic potential. IL-1beta did not influence extracellular matrix adhesion, whereas it significantly enhanced the invasiveness of three of the six cell lines. TGF-beta1 affected the adhesion of one cell line, and exerted contrasting effects on Matrigel invasion of different cell lines.

CONCLUSIONS

IL-1beta enhances the invasive capacity of pancreatic cancer cells, whereas TGF-beta1 has paradoxical effects on pancreatic cancer cells; this makes it difficult to interfere with TGF-beta1 signaling in pancreatic cancer treatment.

Molecular therapy in pancreatic adenocarcinoma

Pancreatic cancer is one of the commonest causes of death from cancer. Despite therapy with surgery, conventional chemotherapy, and radiation, 5-year survival for patients with this diagnosis remains poor. However, advances in the molecular understanding of this malignant disease over the past 5 years might lead to new treatment strategies. Strategies of gene therapy, antiangiogenic treatments, immunotherapy, and signal-transduction inhibition are in preclinical development. This review presents an overview of molecular therapy in pancreatic cancer.