The pancreatitis-associated protein I promoter allows targeting to the pancreas of a foreign gene, whose expression is up-regulated during pancreatic inflammation

Assembly PCR synthesis of optimally designed, compact, multi-responsive promoters suited to gene therapy application

Gene therapy has the potential to provide innovative treatments for genetic and non-genetic diseases, with the ability to auto-regulate expression levels of therapeutic molecules so that they are produced locally and in direct response to disease activity. Generating disease responsive gene therapy vectors requires knowledge of the activation profile of transcription factors (TFs) during active disease, in order to assemble binding sites for these TFs into synthetic promoters, which can be appropriately activated by the disease process. In this study, we optimised a PCR random assembly approach to generate promoters with optimal spacing between TF binding sites (TFBSs) and their distance from the TATA box. In promoters with optimal spacing, it was possible to demonstrate activation by individual transcription pathways and either additive or synergistic promoter activation when transfected cells were treated with combined stimuli. The kinetics and sensitivity of promoter activation was further explored in transduced cells and when lentivirus was directly delivered to mouse paws a synthetic promoter demonstrated excellent activation by real-time imaging in response to local inflammation.

Intestinal adaptation and Reg gene expression induced by antidiabetic duodenal-jejunal bypass surgery in Zucker fatty rats

The antidiabetic mechanism of bariatric surgery includes specific changes in the secretion of incretins. To identify additional players originating from the gut, we evaluated the effects of duodenal-jejunal bypass (DJB) in morbidly obese Zucker fatty rats. A fast relief of hyperglycemia and hyperinsulinemia was achieved even before a significant weight loss occurred. Fourteen days after DJB, we characterized the changes in intestinal histochemistry in the bypassed duodenum and shortcut jejunum that was reanastomosed directly to the starting point of the duodenum and compared with the corresponding regions of sham-operated rats. The bypassed duodenum exhibited mucosal atrophy and apoptosis and decreased proliferative renewal. In shortcut jejunum, DJB resulted in 40% significantly enlarged intestinal circumference and increased epithelial proliferation, especially in putative transit-amplifying (TA) cells and the crypt. Because Reg family proteins promote cell growth and survival, we explored their expression in the intestine. With the use of immunohistochemistry, Reg1, -3α, and -3β were normally expressed in intestinal mucosa. After DJB, the level of Reg1 protein was reduced, whereas Reg3α and -3β were not changed in bypassed duodenum. Downstream in shortcut jejunum, the levels of Reg1 and -3β were greatly induced and especially concentrated in the putative TA cells. Our results revealed significant changes in the integrity and proliferation of the intestinal mucosa as a consequence of DJB, and in cell- and isoform-specific expression of Reg proteins within the replicating mucosal epithelium, and provide evidence indicating that the activation of Reg proteins may contribute to intestinal compensation against increased load and/or to improving insulin sensitivity.

Role of oxidative stress in pancreatic inflammation

Reactive oxygen and reactive nitrogen species (ROS/RNS) have been implicated in the pathogenesis of acute and chronic pancreatitis. Clinical and basic science studies have indicated that ROS/RNS formation processes are intimately linked to the development of the inflammatory disorders. The detrimental effects of highly reactive ROS/RNS are mediated by their direct actions on biomolecules (lipids, proteins, and nucleic acids) and activation of proinflammatory signal cascades, which subsequently lead to activation of immune responses. The present article summarizes the possible sources of ROS/RNS formation and the detailed signaling cascades implicated in the pathogenesis of pancreatic inflammation, as observed in acute and chronic pancreatitis. A therapeutic ROS/RNS-scavenging strategy has been advocated for decades; however, clinical studies examining such approaches have been inconsistent in their results. Emerging evidence indicates that pancreatitis-inducing ROS/RNS generation may be attenuated by targeting ROS/RNS-generating enzymes and upstream mediators.

Internal radiotherapy of liver cancer with rat hepatocarcinoma-intestine-pancreas gene as a liver tumor-specific promoter

The hepatocarcinoma-intestine-pancreas (HIP) gene, also called pancreatitis-associated protein-1 (PAP1) or Reg IIIalpha, is activated in most human hepatocellular carcinomas (HCCs) but not in normal liver, which suggests that HIP regulatory sequence could be used as efficient liver tumor-specific promoters to express a therapeutic polynucleotide in liver cancer. The sodium iodide symporter (NIS), which has recognized therapeutic and reporter gene properties, is appropriate to evaluate the transcriptional strength and specificity of the HIP promoter in HCC. For this purpose, we constructed a recombinant rat HIP-NIS adenoviral vector (AdrHIP-NIS), and evaluated its performance as a mediator of selective radioiodide uptake in tumor hepatocytes. Western blot, immunofluorescence, and iodide uptake assays were performed in AdrHIP-NIS-infected primary hepatocytes and transformed hepatic and nonhepatic cells. Nuclear imaging, tissue counting and immunohistochemistry were performed in normal and HCC-bearing Wistar rats infected with AdrHIP-NIS intratumorally or via the hepatic artery. In AdrHIP-NIS-infected transformed hepatic cells, functional NIS was strongly expressed, as in cells infected with a cytomegalovirus-NIS vector. No NIS expression was found in AdrHIP-NIS-infected normal hepatocytes or transformed nonhepatic cells. In rats bearing multinodular HCC, AdrHIP-NIS triggered functional NIS expression that was preferential in tumor hepatocytes. Administration of 18 mCi of (131)I resulted in the destruction of AdrHIP-NIS-injected nodules. This study has identified the rHIP regulatory sequence as a potent liver tumor-specific promoter for the transfer of therapeutic genes, and AdrHIP-NIS-mediated (131)I therapy as a valuable option for the treatment of multinodular HCC.

The homeobox gene Cdx1 belongs to the p53-p21(WAF)-Bcl-2 network in intestinal epithelial cells

Because the Cdx1 homeobox gene stimulates proliferation and induces transformation and tumorigenesis, it has been investigated whether it is involved in the complex network comprising p53, p21(WAF), and Bcl-2 in intestinal epithelial cells. Non-transformed intestinal IEC-6 cells and colon adenocarcinoma SW480 cells were used to study the putative molecular relationship between Cdx1, p53, p21(WAF), and Bcl-2. Wild-type p53 inhibited the transcriptional activity of the Cdx1 promoter whereas the inactive mutant p53(mut22/23) had no effect. Induction of Cdx1 expression had no direct effect on p53 expression and activity. However, it inhibited the transcriptional activity of the p21(WAF) promoter through Cdx1 binding to the p21(WAF) TATA-box and increased the transcriptional activity of the Bcl-2 promoter P2 through a consensus Cdx-binding site. Finally, compared to control cells, Cdx1-overexpressing cells were more resistant to adriamycin-induced apoptosis, probably because they do not show concomitant decrease in endogenous Bcl-2 level. In conclusion, Cdx1 is a negatively regulated target of p53 in intestinal cells. Its regulation of p21(WAF) and Bcl-2 is opposite to that of p53 and is p53-independent. Cdx1 belongs to the regulatory networks of apoptosis, proliferation, and differentiation. These results emphasize the oncogenic potential of Cdx1.

Endogenous regulation of a therapeutic transgene restores homeostasis in arthritic joints

The treatment of chronic inflammatory diseases is complicated by their unpredictable, relapsing clinical course. Here, we describe a new strategy in which an inflammation-regulated therapeutic transgene is introduced into the joints to prevent recurrence of arthritis. To this end, we designed a recombinant adenoviral vector containing a two-component, inflammation-inducible promoter controlling the expression of human IL-10 (hIL-10) cDNA. When tested in vitro, this system had a low-level basal activity and was activated four to five orders of magnitude by various inflammatory stimuli, including TNF-alpha, IL-1 beta, IL-6, and LPS. When introduced in joints of rats with recurrent streptococcal cell wall-induced arthritis, the IL-10 transgene was induced in parallel with disease recurrence and effectively prevented the influx of inflammatory cells and the associated swelling of the joints. Levels of inflammation-inducible hIL-10 protein within the joints correlated closely with the severity of recurrence. An endogenously regulated therapeutic transgene can thus establish negative feedback and restore homeostasis in vivo while minimizing host exposure to the recombinant drug.

Cdx1 promotes cellular growth of epithelial intestinal cells through induction of the secretory protein PAP I

Expression of the Cdx1 homeobox gene in epithelial intestinal cells promotes cellular growth and differentiation. Cdx1and the Pancreatitis Associated Protein I (PAP I) are concomitantly expressed in the epithelial cells of the lower part of the intestinal crypts. Because Cdx1 is a transcription factor and PAP I, in other tissues, is a proliferative factor, we looked for a relationship between these two proteins in the intestinal-derived IEC-6 cells. After stable transfection with a Cdx1 expression vector, they produce high levels of the PAP I transcript and protein indicating a functional link between the two genes. Demonstration of Cdx1 binding to the PAP I promoter region and suppression of PAP I induction after deletion of the corresponding sequence indicated that Cdx1 is a transcription factor controlling PAP I gene expression in intestinal cells. By infecting IEC-6 cells with adenoviruses expressing PAP I, we demonstrated that PAP I induces mitosis in these cells. On the other hand, inhibition of the PAP I expression in the IEC-6 Cdxl-expressing cells using an antisense strategy confirmed the requirement of this protein for the effect of Cdx1 on cell growth. Finally, addition of the immunopurified PAP I to the culture medium promotes cell growth of the IEC-6 cells in a dose-dependent manner. Maximal effect was obtained at 1 ng/ml. Taken together these results demonstrate that PAP I is a target of the Cdx1 homeobox gene in intestinal cells which participates in the regulation of intestinal cell growth via an autocrine and/or paracrine mechanism.

Pancreatitis-associated protein is upregulated in mouse pancreas during acute pancreatitis

Pancreatitis-associated protein I (PAP I) is a pancreatic secretory protein strongly expressed during acute pancreatitis in the rat and human. We hypothesized that its expression was part of a general and coordinated response of the organ against aggression. An opposite pattern of PAP I mRNA expression has recently been described in the mouse. The murine PAP I mRNA was described to be highly expressed in normal pancreas and down-regulated during pancreatitis. The important implications of these unexpected findings led us to investigate the expression of murine PAP I in cerulein-induced pancreatitis. Northern blot analysis demonstrated a very low level of PAP I mRNA in the healthy mouse pancreas and strong overexpression during acute pancreatitis. Western blot analysis confirmed that changes in pancreatic PAP I levels were parallel to those of the mRNA and the protein was localized by immunohistochemistry to the acinar cells. It was concluded that, during the course of acute pancreatitis, the pattern of PAP I expression in the mouse pancreas was comparable to that already observed in the rat and human. Although we have no explanation for the discrepancy between our results and those recently reported, the expression pattern of PAP I in the mouse exocrine pancreas described in the present study suggests that the pancreatic response to aggression might be conserved in mammals.

Tumor necrosis factor alpha triggers antiapoptotic mechanisms in rat pancreatic cells through pancreatitis-associated protein I activation

BACKGROUND & AIMS

Tumor necrosis factor (TNF)-alpha contributes to the development of acute pancreatitis. Because TNF-alpha is involved in the control of apoptosis, we studied its interaction with the pancreatic apoptotic pathway.

METHODS

Pancreatic acinar AR4-2J cells were used. Apoptosis was monitored by morphologic and biochemical criteria.

RESULTS

TNF-alpha induced apoptosis in AR4-2J cells. Induction was strongly enhanced in cells treated with actinomycin D, suggesting that TNF-alpha activated concomitantly an antiapoptotic mechanism through newly synthesized proteins. This mechanism involved activation of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein (MAP) kinases because their inhibition worsened TNF-alpha-induced apoptosis. The antiapoptotic pancreatitis-associated protein (PAP) I is a candidate for mediating TNF-alpha activity. Its expression is induced by TNF-alpha, and cells overexpressing PAP I show significantly less apoptosis on exposure to TNF-alpha. We examined whether TNF-alpha induction of PAP I expression was mediated by NF-kappaB or MAP kinases by using specific inhibitors of both pathways. Inhibition of NF-kappaB had no effect. However, inhibitors of MEK1 eliminated PAP I induction.

CONCLUSIONS

TNF-alpha induces concomitantly proapoptotic and antiapoptotic mechanisms in pancreatic AR4-2J cells. Antiapoptotic mechanisms are mediated by NF-kappaB and MAP kinases, and PAP I is one of the effectors of apoptosis inhibition.

In vivo dose threshold effect of adenovirus-mediated factor VIII gene therapy in hemophiliac mice

While much is known about adenovirus biology from its development as a therapeutic gene delivery vehicle, an important question remains regarding the appropriate in vivo vector dose. We describe here an in vivo dose threshold effect with an adenoviral vector expressing human Factor VIII (FVIII) in hemophiliac mice. Upon administration of vector doses between 6 x 10(10) and 2 x 10(10) vector particles per mouse, FVIII was expressed linearly, whereas a dose of 1 x 10(10) vector particles per mouse did not result in detectable levels of FVIII activity. In contrast, in vitro transduction studies demonstrated linear transgene expression over 2 to 3 log units. To further define this dose threshold effect, a vector-mixing study was performed. Mice were injected with a total vector dose of 6 x 10(10) particles containing admixtures of FVIII vector plus a control vector lacking a transgene (null vector). With the admixture, FVIII activity was detected in mice that received 1 3 1010 particles of the FVIII vector, indicating that maintenance of the total viral input at 6 x 10(10) particles per mouse circumvented the threshold dose effect. This threshold dose effect could not be attributed to dose-dependent differences in liver toxicity nor to dose-dependent induction of cellular and humoral immune responses. Southern blot analysis of livers revealed that mice receiving the vector admixture contained FVIII DNA, accounting for the observed FVIII expression, whereas mice receiving 1 x 10(10) particles of FVIII vector had barely detectable FVIII DNA. These results suggest that the threshold effect is an in vivo phenomenon that will have important implications in defining the therapeutic window of adenoviral vectors for clinical applications.

Arginine induces apoptosis and gene expression of pancreatitis-associated protein (PAP) in rat pancreatic acinar AR4-2J cells

Arginine-induced pancreatic acinar cell injury has been reported in vivo, but the mechanism involved is unknown. In this study we investigated the effects of arginine on the cell morphology and pancreatitis-associated protein (PAP) gene expression in rat pancreatic acinar AR4-2J cells in vitro. Arginine inhibited the proliferation of AR4-2J cells in a dose-dependent manner. This decrease in proliferation was due to an increase in apoptosis, as assessed by cell morphology and DNA fragmentation. PAP messenger RNA (mRNA) was expressed at doses of 2.5 and 5.0 mg/ml of arginine, and a time-course study showed that the expression started 2 h after arginine addition and peaked at 6 h. Apoptosis was rarely seen when PAP mRNA was highly expressed, but occurred when PAP mRNA expression was decreased. These results suggest that arginine induces apoptosis and PAP gene expression in pancreatic acinar cells and that PAP might inhibit the induction of apoptosis.

Adenovirus technology for gene manipulation and functional studies

Recombinant adenoviral vectors are highly efficient at gene transfer in a broad spectrum of cell types and species, and have been used, both in vitro and in vivo, to achieve gain or loss of function in functional studies. In recent years, there have been several significant advances in adenovirus technologies, including new generations of vectors, improved production systems and sophisticated methods of delivery. In this review, recent progress and innovative applications are discussed to demonstrate the potential of the recombinant adenoviral vector as an effective tool in functional genomics.

An adenoviral vector regulated by hypoxia for the treatment of ischaemic disease and cancer

Recombinant adenoviral vectors have a number of advantages for gene therapy, including transduction of a range of dividing and non-dividing cell types. However, this broad range may be a disadvantage if non-target cells are transduced and are adversely affected by expression of the transferred gene. Here we describe a novel adenoviral vector in which transcription of the transgene is restricted to the patho-physiological condition of low oxygen tension (hypoxia). Hypoxia activates the expression of a number of genes, principally via the stabilisation of members of the bHLH/PAS family of transcription factors that bind to a con- sensus DNA sequence, the hypoxia response element (HRE). We have configured an optimised HRE expression cassette into an adenoviral vector, AdOBHRE. A range of cell types, including primary human skeletal muscle, when transduced with AdOBHRE display a low basal level of transgene expression that is highly induced in hypoxia to levels equivalent to that obtained from the CMV promoter. The AdOBHRE vector could be exploited for transcriptionally targeted gene therapy for the treatment of diseases such as cancer, peripheral arterial disease, arthritis and anaemia where tissue hypoxia is a cardinal feature.

pap, reg Ialpha and reg Ibeta mRNAs are concomitantly up-regulated during human colorectal carcinogenesis

We have established the phenotype of a colorectal tumor by partial sequencing of 2166 transcripts that were eventually arrayed on high-density filters. These filters were used for differential screening with mRNAs of colorectal cancer and normal adjacent mucosa to characterize genes whose expression is altered in colorectal carcinoma. Three genes encoding related proteins, PAP, reg Ialpha and reg Ibeta, were over-expressed in cancer. Northern-blot analysis confirmed that their expression was very low in normal colonic epithelial cells, but elevated in 75% of tumors. Western blotting with specific antibodies to pap and reg Ialpha revealed in tumors a single band of the expected size ( 15-16 kDa), demonstrating synthesis of the proteins. Pap was localized by immunohistochemistry to the cytoplasm of epithelial cells. In cancerous tissue, many cells showed a strong staining signal, but the proportion of stained cells was variable among patients. In normal mucosa, staining was light and restricted to a few cells scattered in the epithelium. Similar results were obtained with antibodies against reg Ialpha. No significant relationship was found between concentrations of pap, reg Ialpha or reg Ibeta and clinical outcome. We looked at potential effectors of pap/reg gene over-expression by testing, in 2 adenocarcinoma cell lines, the efficacy of the pap promoter at driving a reporter gene; strong induction was observed upon exposure to IFNgamma and IL-6. By analogy with observations in hepatocellular carcinoma, our results suggest that prevention of PAP/reg expression in normal colon cells by silencing their gene promoters is relieved during colon carcinogenesis, allowing their up-regulation by mediators such as cytokines.

PAP gene transcription induced by cycloheximide in AR4-2J cells involves ADP-ribosylation

We report in this paper that cycloheximide induces PAP mRNA expression in the pancreatic acinar cell line AR4-2J in a dose- and time-dependent manner. We analyzed whether stabilization of the PAP mRNA or the direct induction of its transcription contributed to the induction of PAP mRNA expression by the drug. We first infected the cells, which do not express PAP mRNA constitutively, with a recombinant adenovirus in which the PAP cDNA was subcloned downstream of the CMV promotor, to obtain high levels of transcript. Then, transcription was pharmacologically blocked, the cells were treated with cycloheximide, and the PAP mRNA concentration was monitored over 8 h by Northern blot. PAP mRNA concentration remained unchanged for 4 h and then decreased in both cycloheximide-treated and control cells, ruling out a significant contribution of posttranscriptional regulation in cycloheximide induction. Direct regulation of gene transcription is therefore likely and we investigated whether it could involve ADP-ribosylation. Cycloheximide-induced cells were treated with two chemical inhibitors of poly(ADP-ribose) polymerase. 3-Aminobenzamide inhibited 75% of PAP gene induction and 4-hydroxyquinazolone, the highly specific inhibitor of the enzyme, blocked almost completely PAP expression, suggesting that ADP-ribosylation was indeed required for the upregulation of PAP gene expression by cycloheximide.

Physiologically responsive gene therapy

The goal of physiologically responsive gene therapy is to allow a host's endogenous regulatory mechanisms to control the production of therapeutic proteins (effectors). Ideally, effector production would be switched on in response to specific signals, stay within therapeutic limits and be switched off when no longer needed. In this way, the unwanted consequences of constitutive, high-level effector expression could be avoided. While recent studies have shown that transgenes can be regulated within animal hosts, they have also highlighted significant problems that require much further research.