Widespread long-term gene transfer to mouse skeletal muscles and heart

Studies on in vivo gene transfer in pituitary tumors using herpes-derived and adenoviral vectors

Suicide gene therapy has met limited success for the treatment of rat pituitary tumors. In order to determine the cause of primary pituitary tumor resistance to suicide gene therapy, we studied the transgene expression of an adenoviral (Ad.RSV.beta gal.nls) and a herpes simplex virus-derived (tsK/beta-gal) vector, both harboring the beta-galactosidase reporter gene in rat prolactinomas. Rats carrying experimental prolactinomas received bilateral 1 microl intrapituitary injections of either saline (saline group), 5 x 10(5) plaque-forming units (pfu) tsK/beta-gal (HSV Group) or 5 x 10(5) pfu Ad.RSV.beta gal.nls (RAd Group). Two or seven days later the tumors were examined. Macroscopic inspection of glands injected with either vector showed that the tissue expressing beta-gal was concentrated at the ventral area around the site reached by the tip of the needle. Almost no transgene expression was observed in other sites. Cellularity and lactotrophic cell density was not affected by saline or virus injection. In the injected areas, apoptotic levels were (x +/-S.E.M.): 9.3+/-0.5, 22.1+/-1.1 and 31.7+/-1.4%, for the saline, RAd and HSV groups, respectively. Serum prolactin and growth hormone levels were not affected by virus injection. We conclude that the low diffusibility of viral suspensions in the pituitary tissue may constitute a significant obstacle for achieving full remission of in situ pituitary tumors in rats.

Full kringles of plasminogen (aa 1–566) mediate complete regression of human MDA-MB-231 breast tumor xenografted in nude mice

Since kringle (K)5, not present in the angiostatin molecule, was shown to be a key functional domain possessing potent antiangiogenic activity, we have evaluated a new plasminogen-derived fragment, consisting of the N-terminal part of human plasminogen, that included the complete secondary structure of K1-5 (aa 1-566). In contrast to other fragments described to date, K1-5 includes cysteine residues at positions 543, 555 and 560 allowing the formation of the three disulfide bonds lying within K5. Vascular endothelial cell proliferation and migration assays revealed that a replication-defective adenovirus (AdK1-5(1-566)), expressing K1-5 (aa 1-566), was dose dependently more potent that AdK1-3(1-354), an adenovirus that expresses only the first three kringles. In contrast to AdK1-3(1-354), a single intratumoral injection of AdK1-5(1-566) into MDA-MB-231 breast human carcinoma tumors was followed by a total regression of 40% of the tumor and by significant arrest of tumor growth (90%), which was correlated with a drastic decrease of functional neovascularization into the tumors. Furthermore, systemic delivery of AdK1-5(1-566) in mice inhibited the lung invasion of melanoma B16-F10 cells by 87%. Our findings provide evidence that the full kringles of plasminogen (aa 1-566) may be much more potent than K1-3 (aa 1-354), for the suppression of angiogenesis, tumor growth and metastatic dissemination.

Adenoviral vectors: development and application

One of the prerequisites for the successful application of gene vaccination and therapy is the development of efficient gene delivery vectors. The rate-limiting nature of vectors was clearly manifested during the first wave of gene therapy testing, resulting in the demand for more effective and suitable vector systems. Adenoviral (Ad) vectors have recently played a central role in the development of gene-vector technology due to their practical advantages and potential applications. A large number of preclinical and clinical studies both have generated an overwhelming amount of data and literature on this vector system. It is the intention of this article to provide a systematic and broad spectrum review of this system, outlining the principle, potential, and limitations, and evaluating the rational development of this delivery approach. Recombinant adenoviruses (Ad), helper cell lines, and related technologies have been developed and applied to many indications owing to progress in virological research, molecular and cellular biology, eukaryotic protein expression, recombinant vaccines, and gene therapy. The technical depth this article covers should be useful to both the experienced researcher and to beginners in this field.

Reversal of the phenotype by K-rasval12 silencing mediated by adenovirus-delivered siRNA in human pancreatic cancer cell line Panc-1

AIM: To investigate the in vitro antitumor effect of adenovirus-mediated small interfering RNAs (siRNAs) on pancreatic cancer and the associated mechanism.

METHODS: A 63-nucleotide (nt) oligonucleotide encoding K-ras^val12 and specific siRNA were introduced into pSilencer 3.1-H1, then the H1-RNA promoter and siRNA coding insert were subcloned into pAdTrack to get plasmid pAdTrackH1-K-ras^val12. After homologous recombination in bacteria and transfections of such plasmids into a mammalian packaging cell line 293, siRNA expressing adenovirus AdH1-K-ras^val12 was obtained. Stable suppression of K-ras^val12 was detected by Northern blot and Western blot. Apoptosis in Panc-1 cells was detected by flow cytometry.

RESULTS: We obtained adenovirus AdH1-K-ras^val12 carrying the pSilencer 3.1-H1 cassette, which could mediate gene silencing. Through siRNA targeted K-ras^val12, the oncogenic phenotype of cancer cells was reversed. Flow cytometry showed that apoptotic index of Panc-1 cells was significantly higher in the AdH1-K-ras^val12-treatment group (18.70% at 72 h post-infection, 49.55% at 96 h post-infection) compared to the control groups (3.47%, 3.98% at 72 and 96 h post-infection of AdH1-empty, respectively; 4.21%, 3.78% at 72 and 96 h post-infection of AdH1-p53, respectively) (P<0.05).

CONCLUSION: These results demonstrate that adenoviral vectors can be used to mediate RNA interference (RNAi) to induce persistent loss of functional phenotypes. In gene therapy, the selective down-regulation of only the mutant version of a gene allows for highly specific effects on tumor cells, while leaving the normal cells untouched. In addition, the apoptosis of pancreatic cancer cell line Panc-1 can be induced after AdH1-K-ras^val12 infection. This kind of adenovirus based on RNAi might be a promising vector for cancer therapy.

Reflecting on 80 years of excellence

A small group of members of the American Society for Clinical Investigation began chatting in 1916 about the possibility of launching a new biomedical research journal. By October 1924, they managed to make the idea a reality with the publication of the first issue of the Journal of Clinical Investigation. Our 80th birthday seems an appropriate time to reflect on the history of biomedical science as it has been played out on our pages.

Adenovirus-mediated overexpression of tissue inhibitor of metalloproteinases-1 in the liver: efficient protection against T-cell lymphoma and colon carcinoma metastasis

BACKGROUND

Matrix metalloproteinases (MMPs) are critical for metastasis of tumor cells. Tissue inhibitor of metalloproteinases-1 (TIMP-1), a natural MMP inhibitor, was shown to reduce metastasis in different models. Here, we investigated whether increased TIMP-1 levels in the liver achieved by adenoviral gene transfer will effectively inhibit liver metastasis of two independent tumor cell lines.

METHOD

TIMP-1 was transferred with adenoviral vectors into the livers of DBA/2 and Balb/c mice, which were subsequently challenged by hematogenous experimental metastases of the T-cell lymphoma cell line L-CI.5s or the colorectal carcinoma cell line CT-26, respectively.

RESULTS

MMP-9 expression in the liver was induced upon metastasis in both tumor types. Adenoviral gene transfer led to high transduction efficacy as indicated by lacZ expression in 60% of hepatocytes. TIMP-1, a key inhibitor of MMP-9, was expressed at 10(5)-fold higher levels by adenoviral gene transfer as compared with levels achieved in TIMP-1 transgenic mice, previously shown to be inefficient to reduce T-cell lymphoma metastasis. High local and systemic (serum) levels of TIMP-1 led to substantial (94%) reduction of T-cell lymphoma and colorectal carcinoma (73%) experimental liver metastasis.

CONCLUSIONS

Adenoviral gene transfer led to systemic and local TIMP-1 levels sufficient to inhibit metastasis of a highly aggressive T-cell lymphoma, pointing at the requirement of threshold levels for effective anti-metastatic efficacy. This approach was also efficient in a colon carcinoma solid tumor model. We propose that viral gene transfer of TIMP-1 can provide a suitable defense strategy to prevent metastatic spread to the liver.

Mammalian cell transduction and internalization properties of lambda phages displaying the full-length adenoviral penton base or its central domain

In recent years a strong effort has been devoted to the search for new, safe and efficient gene therapy vectors. Phage lambda is a promising backbone for the development of new vectors: its genome can host large inserts, DNA is protected from degradation by the capsid and the ligand-exposed D and V proteins can be extensively modified. Current phage-based vectors are inefficient and/or receptor-independent transducers. To produce new, receptor-selective and transduction-efficient vectors for mammalian cells we engineered lambda by inserting into its genome a GFP expression cassette, and by displaying the penton base (Pb) of adenovirus or its central region (amino acids 286-393). The Pb mediates attachment, entry and endosomal escape of adenovirus in mammalian cells, and its central region (amino acids 286-393) includes the principal receptor-binding motif ((340)RGD(342)). Both the phage chimerae lambda Pb and lambda Pb (286-393) were able to transduce cell lines and primary cultures of human fibroblasts. Competition experiments showed that the transduction pathway was receptor-dependent. We also describe the different trafficking properties of lambda Pb and lambda Pb (286-393). Bafilomycin, which blocks endosome maturation, influenced the intracellular distribution of lambda Pb (286-393), but not that of lambda Pb. The proteasome inhibitor MG-132 improved the efficiency of lambda Pb (286-393)-mediated transduction, but not that of lambda Pb. In summary, this work shows the feasibility of using lambda phage as an efficient vector for gene transfer into mammalian cells. We show that lambda Pb and lambda Pb (286-393) can both mediate receptor-dependent transduction; while only lambda Pb is able to promote endosomal escape and proteasome resistance of phage particles.

Widespread and efficient marker gene expression in the airway epithelia of fetal sheep after minimally invasive tracheal application of recombinant adenovirus in utero

Cystic fibrosis is a common lethal genetic disease caused by functional absence of the cystic fibrosis transmembrane conductance regulator (CFTR). Although a candidate disease for in utero gene therapy, demonstration of potentially therapeutic levels of transgene expression in the fetal airways after minimally invasive gene delivery is a mandatory prerequisite before application of this approach in humans can be considered. We report here on the delivery of a beta-galactosidase expressing adenovirus directly to the airways of fetal sheep in utero using ultrasound-guided percutaneous injection of the trachea in the fetal chest. Injection of adenoviral particles to the fetal airways was not associated with mortality and resulted in low-level expression in the peripheral airways. However, complexation of the virus with DEAE dextran, which confers a positive charge to the virus, and pretreatment of the airways with Na-caprate, which opens tight junctions, increased transgene expression, and a combination of these two enhancers resulted in widespread and efficient gene transfer of the fetal trachea and bronchial tree. Using a percutaneous ultrasound-guided injection technique, we have clearly demonstrated proof of principle for substantial transgene delivery to the fetal airways providing levels of gene expression that could be relevant for a therapeutic application of CFTR expressing vectors.

GSH depletion enhances adenoviral bax-induced apoptosis in lung cancer cells

The utility of dominant acting proapoptotic molecules to induce cell death in cancer cells is being evaluated in preclinical studies and clinical trials. We recently developed a binary adenoviral expression system to enable the efficient gene transfer of Bax and other proapoptotic molecules. Using this system, overexpression of Bax protein in four non-small-cell lung cancer (NSCLC) cell lines, H1299, A549, H226 and H322, was evaluated. The H322 line exhibited significant resistance to Bax-induced cell death compared to the other cell lines. H322 cells had the highest level of glutathione (GSH). GSH levels were significantly decreased following buthionine sulfoximine treatment and this coincided with enhanced apoptosis induction by Ad-Bax in H322 cells. GSH depletion enhanced Bax protein translocation to mitochondrial membranes. These findings suggest that the redox status may be a determinant of Bax-mediated cell death and that manipulation of intracellular thiols may sensitize cells to apoptosis by facilitating Bax insertion into mitochondrial membranes.

Intraneuronal amyloid-β1-42 production triggered by sustained increase of cytosolic calcium concentration induces neuronal death

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence in the brain of senile plaques which contain an amyloid core made of beta-amyloid peptide (Abeta). Abeta is produced by the cleavage of the amyloid precursor protein (APP). Since impairment of neuronal calcium signalling has been causally implicated in ageing and AD, we have investigated the influence of an influx of extracellular calcium on the metabolism of human APP in rat cortical neurones. We report that a high cytosolic calcium concentration, induced by neuronal depolarization, inhibits the alpha-secretase cleavage of APP and triggers the accumulation of intraneuronal C-terminal fragments produced by the beta-cleavage of the protein (CTFbeta). Increase in cytosolic calcium concentration specifically induces the production of large amounts of intraneuronal Abeta1-42, which is inhibited by nimodipine, a specific antagonist of l-type calcium channels. Moreover, calcium release from endoplasmic reticulum is not sufficient to induce the production of intraneuronal Abeta, which requires influx of extracellular calcium mediated by the capacitative calcium entry mechanism. Therefore, a sustained high concentration of cytosolic calcium is needed to induce the production of intraneuronal Abeta1-42 from human APP. Our results show that this accumulation of intraneuronal Abeta1-42 induces neuronal death, which is prevented by a functional gamma-secretase inhibitor.

Delivery of GDNF by an E1,E3/E4 deleted adenoviral vector and driven by a GFAP promoter prevents dopaminergic neuron degeneration in a rat model of Parkinson's disease

A new adenoviral vector (Ad-GFAP-GDNF) (Ad=adenovirus, GFAP=glial fibrillary acidic protein, GDNF=glial cell line-derived neurotrophic factor) was constructed in which (i) the E1,E3/E4 regions of Ad5 were deleted and (ii) the GDNF transgene is driven by the GFAP promoter. We verified, in vitro, that the recombinant GDNF was expressed in primary cultures of astrocytes. In vivo, the Ad-GFAP-GDNF was injected into the striatum of rats 1 week before provoking striatal 6-OHDA lesion. After 1 month, the striatal GDNF levels were 37 pg/microg total protein. This quantity was at least 120-fold higher than in nontransduced striatum or after injection of the empty adenoviral vector. At 3 months after viral injection, GDNF expression decreased, whereas the viral DNA remained unchanged. Furthermore, around 70% of the dopaminergic (DA) neurons were protected from degeneration up to 3 months as compared to about 45% in the control groups. In addition, the amphetamine-induced rotational behavior was decreased. The results obtained in this study on DA neuron protection and rotational behavior are similar to those previously reported using vectors with viral promoters. In addition to these results, we established that a high level of GDNF was present in the striatum and that the period of GDNF expression was prolonged after injection of our adenoviral vector.

Development and validation of a real-time PCR assay for the detection and quantitation of p53 recombinant adenovirus in clinical samples from patients treated with Ad5CMV-p53 (INGN 201)

The purpose of this study was to assess the usefulness of real-time PCR as a quantitative, highly reproducible, and sensitive method, for detecting and quantifying p53 recombinant adenovirus in biological samples from cancer patients receiving injections of Ad5CMV-p53. The dynamic range of this real-time PCR-based assay was wide (at least five orders of magnitude). Our assay used an internal positive control in the same PCR tube that is capable of detecting residual PCR inhibitors. Serial spiked samples in plasma with known quantities of Ad5CMV-p53 were evaluated. The minimum detection limit was 2 pfu per PCR (approximately 50 pfu per ml of plasma) and the quantification values were reproducible. A total of 2069 controls tested with 1780 plasma samples from 286 patients enrolled in gene therapy trials using Ad5CMV-p53 were investigated. Using calibrators to adjust the quantitation value, the results confirmed the good performance of the assay. In conclusion, the high sensitivity, simplicity and reproducibility of the real-time Ad5CMV-p53 assay, allowing screening of large numbers of samples, combined with its wide dynamic range, make this method particularly suitable for monitoring gene therapy trials.

Viral IL-10 gene transfer inhibits the expression of multiple chemokine and chemokine receptor genes induced by inflammatory or adaptive immune stimuli

Previously we have shown that adenovirus-mediated gene transfer and expression of vIL-10 are able to prolong cardiac allograft survival, through the inhibition of the immune response to both alloantigen and adenoviral antigens. In the current study, we have defined further mechanisms of Ad.vIL-10-mediated prolongation of cardiac allograft survival. E1- and E3-deleted adenoviral vectors encoding beta-galactosidase or vIL-10 were transferred into grafts at the time of transplantation, chemokine and chemokine receptor expression were evaluated by a pathway-specific cDNA array, and the results were confirmed with real time RT-PCR on selected genes. Ischemic injury, alloantigen and adenovirus vector induced the expression of multiple pro-inflammatory chemokines in the grafts, which likely amplify allograft rejection. Most of these Th1-related chemokine genes were inhibited or down-regulated by Ad.vIL-10 administration, which may help to decrease leukocytic infiltration and improve graft survival. Among the potent Th1 type chemokines inhibited were the CXCR3 ligands CXCL9 and CXCL10, which could directly inhibit vector-mediated gene expression in myoblasts, although targeting CXCR3 or its ligands did not prolong allograft survival with vIL-10 gene transfer. Ad.vIL-10 administration also induced the expression of the Th2-associated chemokines eotaxin-2 and MIP-1 gamma, suggesting Th1 to Th2 immune deviation. These results demonstrated that the vIL-10 gene transfer inhibits chemokine expression, preventing stimulation of innate and adaptive immunity.

Differential chemokine and chemokine receptor gene induction by ischemia, alloantigen, and gene transfer in cardiac grafts

Transplantation of allogeneic grafts presents several challenges to the innate and adaptive immune systems including chemokine leukocyte recruitment, activation, and effector function. We defined the chemokines and receptors induced by the transplant procedure/ischemia injury, alloantigen and gene transfer vector administration in murine cardiac grafts. E1, E3 deleted AdRSVbetagal was transferred into grafts at the time of transplantation, grafts were harvested after 1-14 days, and a pathway-specific cDNA array was used to evaluate the levels of 67 chemokine and chemokine receptor genes. Transplantation resulted in ischemic injury and induction of a number of similar genes in both the syngeneic and allogeneic grafts, such as CXCL1 and CXCL5, which increased dramatically on day 1 and returned rapidly to baseline in the syngeneic grafts. Alloantigen stimulated the adaptive immune response and induced the presence of more inflammatory genes within the grafts, particularly at later time points. The adenovirus vector induced a broader panel of genes, among them potent inflammatory chemokines CXCL9 and CXCL10, that are induced earlier or more strongly compared with alloantigen stimulation alone. As alloantigen and adenovirus vectors both induce similar sets of genes, targeting these molecules may not only inhibit alloimmunity, but also enhance the utility of the gene transfer vector.

Adenovirus transduction induces expression of multiple chemokines and chemokine receptors in murine beta cells and pancreatic islets

Adenoviral vectors are highly efficient for transferring genes to islets. However, the inflammatory and immune responses stimulated by adenovirus may be detrimental to islet survival. Given the role of chemokines and their receptors in inflammation, we analyzed their expression in isolated murine islets, in a murine beta cell line and in syngeneic islet grafts after adenovirus transduction (AdRSVLacZ). AdRSVLacZ transduction enhanced and induced the expression of a variety of chemokines. Transduced syngeneic transplanted islets showed significantly enhanced expression of multiple chemokines and receptors, including monocyte chemoattractant protein-1 (MCP-1), CC chemokine receptor 2 (CCR2) and regulated upon activation, normal T cell expressed and secreted (RANTES), compared with untransduced islet grafts. AdRSVLacZ-transduced islet grafts had significant mononuclear infiltrates, and in situ hybridization demonstrated intragraft expression of MCP-1, CCR2 and RANTES. Although adenovirus transduction did not impair in vitro insulin secretion, diabetes was reversed in only one of six recipients of a marginal mass of AdRSVLacZ-transduced islets, compared with six of six control recipients. In conclusion, multiple chemokines and chemokine receptors are expressed by murine islets constitutively and in response to adenovirus transduction. Adenovirus transduction impairs engraftment of marginal mass of transplanted islets. This is not because of direct vector toxicity of islet secretory capacity, but may be related to host innate immunity in response to adenovirus vector.

A gene-deleted adenoviral vector results in phenotypic correction of canine hemophilia B without liver toxicity or thrombocytopenia

Many approaches for treating hemophilia via gene transfer have been attempted in large animal models but all have potential drawbacks. Recombinant adenoviral vectors offer high-efficiency transfer of an episomal vector but have been plagued by the cytotoxicity/immunogenicity of early-generation vectors that contain viral genes. In our current study, we have used a nonintegrating helper-dependent (HD) adenoviral vector for liver-directed gene transfer to achieve hemostatic correction in a dog with hemophilia B. We measured plasma canine factor IX (cFIX) concentrations at a therapeutic range for up to 2.5 months and normalization of the whole blood clotting time (WBCT) for about a month. This was followed by a decrease and stabilized partial correction for 4.5 months. Hepatic gene transfer of a slightly lower dose of the HD vector resulted in WBCTs that were close to normal for 2 weeks, suggesting a dose threshold effect in dogs. In sharp contrast to other studies using first- or second-generation adenoviral vectors, we observed no vector-related elevation of liver enzymes, no fall in platelet counts, and normal liver histology. Taken together, this study demonstrates that injection of an adenoviral HD vector results in complete but transient phenotypic correction of FIX deficiency in canine models with no detectable toxicity.

In vivo high-efficiency transcoronary gene delivery and Cre-LoxP gene switching in the adult mouse heart

High-efficiency somatic gene transfer in adult mouse heart has not yet been achieved in vivo. Here, we demonstrate high-efficiency in vivo transcoronary gene delivery to the adult murine myocardium using a catheter-based technique with recombinant adenovirus (AdV) and adeno-associated virus (AAV) vectors in normal and genetically engineered mice. The method involves immersion hypothermia followed by transient aortic and pulmonary artery occlusion with proximal intra-aortic segmental injection of cardioplegic solution containing substance P and viral vectors. Gene expression measured using a LacZ marker gene was observed throughout both ventricles. The expression efficiency of a cytoplasmic LacZ marker gene in the left ventricular myocardium was 56.4+/-14.5% (mean+/-s.d.) at 4 days with an AdV vector, and with an AAV vector it was 81.0+/-5.9% at 4 weeks. Following AAV gene transfer, no gene expression was found in kidney, brain, lung, and spleen, but there was slight expression in liver. In addition, we demonstrate temporally controlled genetic manipulation in the heart with an efficiency of 54.6+/-5.2%, by transferring an AdV vector carrying Cre recombinase in ROSA26 flox-LacZ reporter mice. Procedure-related mortality was 16% for AdV and zero for AAV transfer. Thus, this method provides efficient, relatively homogeneous gene expression in both ventricles of the adult mouse heart, and offers a novel approach for conditional gene rescue or ablation in genetically engineered mouse models.

Optimized, highly efficient transfer of foreign genes into newborn mouse hearts in vivo

Expression of foreign genes in vivo is a standard method to disclose functions of specific genes and to alter physiological conditions in distinct cell types and tissues. Virus-mediated gene transfer has proved to be a valuable tool for directed gene expression in vivo complementary to transgenic approaches. However, several problems associated with routes of application, endurance of gene expression, and efficiency of infections still have to be solved. We have optimized a gene transfer protocol into hearts of newborn mice to achieve widespread long-lasting expression using adenoviral vectors. Intrathoracic injection of high-titer adenoviral preparations (10(8)pfu) led to expression of foreign genes in >71+/-8% of all heart cells for >50 days after infection without any morphological signs of cardiac malfunction, inflammation, or immune response. This approach might be adapted to long-term cellular studies in vivo since 5 months after infection up to 20% of all cardiac cells still expressed virally encoded genes. Successful and efficient expression of other gene of interest can be easily controlled by co-injection of low titers of a reporter vector encoding EGFP (10(6)pfu).

Inducible cAMP early repressor, an endogenous antagonist of cAMP responsive element-binding protein, evokes neuronal apoptosis in vitro

Active CREB (cAMP responsive element-binding protein) transcription factor is crucial for neuronal survival. Several members of the CREM/ICER (cAMP responsive element modulator/inducible cAMP early repressor) protein family may act as endogenous CREB antagonists. However, their involvement in a process of programmed cell death remains unexplored. Here we report that ICER may play such a role in neuronal apoptosis because it is upregulated in apoptotic neurons in vitro, and overexpression of ICER, delivered in adenoviral vector, evokes programmed cell death of three different kinds of cultured neurons, namely those derived from hippocampal dentate gyrus, cerebral cortex, and superior cervical ganglion. Reporter gene assay with a promoter containing a CREB-responsive sequence revealed a decrease in both basal and induced CRE-dependent gene expression in neurons overexpressing ICER. Finally, the level of expression of the anti-apoptotic protein Bcl-2, a well known CREB target, was markedly diminished in ICER-treated neurons. We suggest that the naturally occurring CREB functional antagonist ICER may have a specific function in programmed cell death of neurons, probably by silencing the expression of anti-apoptotic genes.

Gene therapy: theoretical and bioethical concepts

Gene therapy holds great promise. Somatic gene therapy has the potential to treat a wide range of disorders, including inherited conditions, cancers, and infectious diseases. Early progress has already been made in the treatment of a range of disorders. Ethical issues surrounding somatic gene therapy are primarily those concerned with safety. Germline gene therapy is theoretically possible but raises serious ethical concerns concerning future generations.

Inducible cAMP early repressor, an endogenous antagonist of cAMP responsive element-binding protein, evokes neuronal apoptosis in vitro

Active CREB (cAMP responsive element-binding protein) transcription factor is crucial for neuronal survival. Several members of the CREM/ICER (cAMP responsive element modulator/inducible cAMP early repressor) protein family may act as endogenous CREB antagonists. However, their involvement in a process of programmed cell death remains unexplored. Here we report that ICER may play such a role in neuronal apoptosis because it is upregulated in apoptotic neurons in vitro, and overexpression of ICER, delivered in adenoviral vector, evokes programmed cell death of three different kinds of cultured neurons, namely those derived from hippocampal dentate gyrus, cerebral cortex, and superior cervical ganglion. Reporter gene assay with a promoter containing a CREB-responsive sequence revealed a decrease in both basal and induced CRE-dependent gene expression in neurons overexpressing ICER. Finally, the level of expression of the anti-apoptotic protein Bcl-2, a well known CREB target, was markedly diminished in ICER-treated neurons. We suggest that the naturally occurring CREB functional antagonist ICER may have a specific function in programmed cell death of neurons, probably by silencing the expression of anti-apoptotic genes.

Gene therapy for prostate cancer: toxicological profile of four HSV-tk transducing adenoviral vectors regulated by different promoters

Adenoviral vector delivery of the Herpes simplex virus thymidine kinase (HSV-tk) gene in combination with the prodrug ganciclovir (GCV) has been tested in phase I clinical trials for prostate cancer and found to exhibit a satisfactory toxicity profile. We have developed additional adenoviral vectors with differing promoters to optimize the expression profile and in the present study evaluate the potential systemic toxicity of these vectors. Four recombinant adenoviral vectors that express the HSV-tk gene were generated using three different promoters: CMV (leftward orientation); RSV (both rightward and leftward orientation); and the mouse caveolin-1 (cav-1) promoter (leftward orientation). Efficacy was determined in vitro by cytotoxicity assays in a mouse prostate cancer cell line, RM-9, and in vivo by treating orthotopic tumors. Potential toxicity was evaluated from liver histology and apoptotic cell counts and enzyme levels in the serum following intravenous adenoviral vector injection. Although there were differences in HSV-tk expression at the protein level among the four vectors there were no significant differences in in-vitro cytotoxicity studies with GCV or in vivo in tumor growth suppression of an orthotopic mouse prostate cancer model in GCV treated mice. Intravenous delivery of high doses of all adenoviral vectors lead to abnormalities in liver function as measured by specific serum markers and histological evaluation of liver tissue and increased levels of apoptosis in the liver. These abnormalities were most prevalent with the vector containing the CMV promoter and the rightward oriented RSV promoter. They were least prevalent in the vector regulated by the cav-1 promoter. Upregulation of specific chemokines, MIP-2 and MIP-1beta was correlated with apoptotic counts. Our results demonstrate that comprehensive toxicological analysis of adenoviral vectors provides internally consistent information that can differentiate vectors with comparable efficacy based on toxicity. In these studies vectors with the cav-1 promoter-driven and leftward RSV-driven HSV-tk gene demonstrated minimal toxicities with cytotoxic effectiveness comparable to more toxic vectors. Our studies further suggest that promoter selection can influence the toxic effects of an adenoviral gene therapy vector.

Hybrid yeast-bacteria cloning system used to capture and modify adenoviral and nonviral genomes

Adenoviral vectors are widely used to express transgenes in vitro and in vivo. A major obstacle to the generation of adenoviral vectors is the manipulation of the large (35 kb) adenoviral genome. We developed a hybrid yeast-bacteria cloning system for the creation of novel adenoviral vectors. The adenovirus 5 (Ad5) genome was cloned into a shuttle vector that contains both yeast and bacterial elements for replication and therefore functions as both a yeast artificial plasmid (YAP) and as a plasmid artificial chromosome (PAC). Any sequence can be introduced into any region of the adenoviral genome via the highly efficient homologous recombination in yeast and then these recombinants are rapidly amplified in bacteria. Adenoviral vectors are generated by introduction of the PAC into the appropriate complementing mammalian cell without the need for plaque purification. Vectors were constructed with deletions in the E1, E3, and/or E4 regions. We have generated more than 100 vectors with a number of different transgenes and regulatory elements. In addition, the YAP/PAC vector was used to capture a DNA fragment encompassing the human factor IX gene, demonstrating the utility of this system to clone and analyze genomic DNA. This novel cloning strategy allows the rapid and versatile construction of adenoviral vectors for gene expression and gene therapy applications.

Ultrasound-guided percutaneous delivery of adenoviral vectors encoding the beta-galactosidase and human factor IX genes to early gestation fetal sheep in utero

In utero gene therapy may provide treatment of genetic diseases before significant organ damage, allow permanent genetic correction by reaching stem cell populations, and provide immune tolerance against the therapeutic transgenes and vectors. We have used percutaneous ultrasound-guided injection as a minimally invasive fetal procedure. First-generation adenoviruses encoding the nuclear localizing beta-galactosidase reporter gene or the human factor IX (hFIX) gene, or colloidal carbon were delivered via the umbilical vein (UV, n = 4), heart (intracardiac [IC], n = 2), liver parenchyma (intrahepatic [HE], n = 11), peritoneal cavity (intraperitoneal [IP], n = 14), skeletal musculature ([intramuscular [IM], n = 11), or the amniotic cavity (intraamniotic [IA], n = 14) to early-gestation fetal sheep (0.3 gestation = day 33-61). Postmortem analysis was performed at 2, 9, or 28 days after injection. Although fetal survival was between 77% and 91% for IP, HE, IA, and IM routes, no fetuses survived UV or IC procedures. The hFIX levels reaching 1900 and 401 ng/ml (IP), 30 ng/ml (HE), 66.5 and 39 ng/ml (IA), and 83 and 65.5 ng/ml (IM), respectively, were determined 2 days after injection and decreased at birth to 16.5 ng/ml (IP), 7 ng/ml (HE), 4.5 ng/ml (IA), and 4 and 0 ng/ml (IM). Polymerase chain reaction (PCR) and immunohistochemistry showed broadest hFIX transgene spread and highest localised beta-galactosidase expression, respectively, after IP administration. Antibodies were observed against vector but not against hFIX.

Recombinant adenovirus shedding after intratumoral gene transfer in lung cancer patients

We conducted two phase 1 trials of direct intratumoral injection of a recombinant E1E3-deleted adenovirus (AdR) encoding either the bacterial enzyme beta-galactosidase (Ad.RSVbetagal) or interleukin 2 (IL2, AdTG5327) into primary nonsmall-cell lung cancers of 21 patients. We report here virus shedding and the duration of virus expression in the tumor after intrabronchial injection of 10(7), 10(8) or 10(9) PFU of adenovirus. The infectious AdR and the viral DNA were detected in PBL, plasma, stool and aerodigestive samples in a dose-dependent manner, since cell cultures and PCRs were found to be positive mainly for samples from patients who received the highest AdR dose (10(9) PFU). We detected beta-galactosidase activity in the tumor biopsy samples of 66% of the patients, seemingly dose related, and only low levels of IL2 mRNA could be detected in tumor biopsy samples. E1 sequences were not detected by PCR in any of the PBL and bronchial samples collected after virus delivery, except in one patient. In this patient, E1 sequences were detected in PBL as well as in tumor biopsy samples collected at days 8, 30 and 60 and were correlated with longer beta-galactosidase expression in tumor samples. PBL tested before and after virus delivery contained both E1 sequences indicating that they did not result from replication-competent adenovirus (RCA) E1 sequences present in the inoculum. In addition, only on the day of the injection was Ad.RSVbetagal also detected in E1-positive PBL, indicating that virus replication in blood was very unlikely.

In vitro and in vivo comparative study of chimeric liver-specific promoters

Targeting therapeutic genes to the liver is essential to improve gene therapy protocols of hepatic diseases and of some hereditary disorders. Transcriptional targeting can be achieved using liver-specific promoters. In this study we have made chimeric constructs combining promoter and enhancer regions of the albumin, alpha 1-antitrypsin, hepatitis B virus core protein, and hemopexin genes. Tissue specificity, activity, and length of gene expression driven from these chimeric regulatory sequences have been analyzed in cultured cells from hepatic and nonhepatic origin as well as in mice livers and other organs. We have identified a collection of liver-specific promoters whose activities range from twofold to less than 1% of the CMV promoter in human hepatoma cells. We found that the best liver specificity was attained when both enhancer and promoter sequences of hepatic genes were combined. In vivo studies were performed to analyze promoter function during a period of 50 days after gene transfer to the mouse liver. We found that among the various chimeric constructs tested in this work, the alpha1-antitrypsin promoter alone or linked to the albumin or hepatitis B enhancers is the most potent in directing stable gene expression in liver cells.

Articular cartilage repair by gene therapy using growth factor-producing mesenchymal cells

OBJECTIVE

To investigate the repair of partial-thickness lesions in rat articular cartilage by combining cell transplantation with transfer of growth factor complementary DNA (cDNA).

METHODS

Mesenchymal cells isolated from rib perichondrium were infected ex vivo with adenoviral vectors carrying bone morphogenetic protein 2 (BMP-2) or insulin-like growth factor 1 (IGF-1) cDNA. The cells were suspended in fibrin glue and applied to mechanically induced partial-thickness cartilage lesions in the patellar groove of the rat femur. The filling of the defects was quantified and the quality and integration of the newly formed tissue were assessed by histochemical and immunohistochemical methods. Uninfected cells or cells infected with a LacZ reporter gene vector served as controls.

RESULTS

Transplanted cells were able to attach to the wounded articular cartilage and were not displaced from the lesions by joint movement. Cells infected with both adenoviral vectors AdBMP-2 and AdIGF-1 produced repair cartilage of hyaline morphology containing a type II collagen-positive but type I collagen-negative proteoglycan-rich matrix that restored the articular surface in most lesions. Uninfected cells either failed to fill up the defects or formed fibrous tissue mainly composed of type I collagen. Excessive cells were partially dislocated to the joint margins, leading to osteophyte formation there if AdBMP-2-infected cells were used. These adverse effects, however, were not seen with AdIGF-1-infected cells.

CONCLUSION

Stimulation of perichondrium-derived mesenchymal cells by transfer of growth factor cDNA in a partial-thickness defect model allows for satisfactory cartilage restoration by a repair tissue comparable with hyaline articular cartilage.

Adenovirus-mediated gene transfer to the transplanted piglet heart after intracoronary injection

BACKGROUND

The advent of cardiac gene therapy in clinical practice requires a more efficient and safer myocardial gene delivery in large animals. A new approach to adenovirus-mediated intracoronary gene transfer in the piglet, using a heterotopic heart transplantation model, was designed to maximize the duration of contact between the vector and the heart in noncoronary flow conditions.

METHODS

Recombinant adenoviruses harboring a nucleus-localized beta-galactosidase gene under the control of a viral promoter were injected into the coronary vessels of the harvested hearts at a dose ranging from 10(10) to 2 x 10(11) pfu. The graft was maintained for 75 min in saline solution and then implanted in the abdomen of recipients. Gene transfer to allografts was evaluated 4 days after grafting by immunohistochemical and enzymatic analysis of beta-galactosidase expression.

RESULTS

Transgene expression was detected in all cardiac areas and up to 64, 44, 32, and 15% of positive nuclei were estimated in the left ventricle wall in four animals out of eleven. In the remaining animals, transgene expression was focally distributed, mainly in the left ventricle wall. PCR analysis revealed the presence of adenoviral sequences, albeit minimal, in exposed organs such as the liver and lung.

CONCLUSIONS

This procedure demonstrated that direct intracoronary gene transfer can be achieved using an ex vivo gene transfer strategy.

IFN-gamma sensitization of prostate cancer cells to Fas-mediated death: a gene therapy approach

While human prostate cancers and cell lines express Fas, most of these cell lines are resistant to Fas-mediated death. In the present studies we addressed the ability of IFN-gamma to influence Fas-mediated cell death in prostate cancer cells. In vitro exposure of the human cell lines LNCaP and PC3 and the mouse cell line RM-1 to agonist anti-Fas antibody and/or soluble Fas ligand resulted in killing of only PC3 cells. However, preincubation with IFN-gamma resulted in synergistic killing in all three cell lines. In vitro treatment of RM-1 with a replication-incompetent adenovirus expressing mouse FasL (Ad.FasL) resulted in maximal cell kill near 40%, which correlated with baseline Fas expression. The addition of IFN-gamma enhanced cell kill to a degree consistent with the resulting higher levels of Fas and maintained synergistic killing at very low doses of vector. Co-inoculation of orthotopic RM-1 primary tumors with Ad.mFasL and an adenovirus expressing mouse IL-12 (Ad.mIL-12) to drive host production of IFN-gamma negated the survival advantage of Ad.mIL-12 alone. However, the staggered injection of Ad.mIL-12 and Ad.FasL achieved almost threefold higher levels of apoptosis in primary tumor tissue and doubled median survival. Therefore, IFN-gamma is capable of bestowing increased sensitivity to Fas-mediated cell death in prostate cancer cells and, in a gene therapy approach, may define a powerful tool to treat prostate cancers.

Adenovirus and adeno-associated virus vectors

Recombinant adenovirus (rAd) and recombinant adeno-associated virus (rAAV) are among the most extensively used vectors in gene therapy studies to date. These two vectors share some similar features such as a broad host range and ability to infect both proliferating and quiescent cells. However, they also possess their own unique set of properties that render them particularly attractive for gene therapy applications. rAd vectors can accommodate larger inserts, mediate transient but high levels of protein expression, and can be easily produced at high titers. Development of gutted rAd vectors has further increased the cloning capacity of these vectors. The gaining popularity of rAAV use in gene therapy can be attributed to its lack of pathogenicity and added safety due to its replication defectiveness, and its ability to mediate long-term expression in a variety of tissues. Site-specific integration, as occurs with wild-type AAV, will be a unique and valuable feature if incorporated into rAAV vectors, further improving their safety. This paper describes these properties of rAd and rAAV vectors, and discusses further development and vector improvements that continue to extend the utility of these vectors, such as cell retargeting by capsid modification, differential transduction by use of serotypes, and extension of the cloning capacity of rAAV vectors by dual vector heterodimerization.

Effect of intratracheal adenoviral vector administration on lung development in newborn rats

Local overexpression of genes that promote lung defense or repair may be helpful in protecting the immature neonatal lung from injuries, but whether the vectors used to administer these genes affect physiological postnatal lung growth has not been investigated. We explored the effect on alveolarization of E1-deleted Adnull vector (Ad5-LMP-null) given intratracheally to 3-day-old rats. Three Adnull doses were evaluated 10(8), 5 x 10(8), and 10(9) TCID(50). Lung morphometry on day 21 showed significant growth disorders with the two higher doses. With 5 x 10(8) TCID(50), absolute lung volume increased significantly (+16%), as did absolute (+20%) and specific (+32%) alveolar airspace volumes, whereas alveolar surface density decreased by 13% (p < 0.009 for all parameters). Lung inflammation was mild, nonsignificant, and occurred mainly with the highest Adnull dose, indicating that it was unlikely to contribute to our results. Adnull instillation induced a significant#10; decrease in terminal bronchiolar cell proliferation as evaluated by proliferating cell nuclear antigen immunostaining (p = 0.02), as well as a 23% decrease in absolute parenchyma elastic fiber length (p = 0.02). Furthermore, lung tropoelastin mRNA content decreased by 25% (p < 0.02). In conclusion, E1-deleted adenoviral vectors can induce lung growth disorders when instilled into the airways of neonatal rats. Interactions with lung matrix turnover may be the main explanation to these deleterious effects.

Gene transfer in higher animals: theoretical considerations and key concepts

Gene transfer technology provides the ability to genetically manipulate the cells of higher animals. Gene transfer permits both germline and somatic alterations. Such genetic manipulation is the basis for animal transgenesis goals and gene therapy attempts. Improvements in gene transfer are required in terms of transgene design to permit gene targeting, and in terms of transfection approaches to allow improved transgene uptake efficiencies.

Expression of a green fluorescence protein-carrier protein into mouse spermatozoa

Intra-testicular inoculation of an adenoviral vector carrying the fusion gene Aequorea victoria green fluorescence protein/rat-liver glycogen synthase (GFP/LGS) resulted in the presence of GFP/GLS in spermatozoa from 7days to, at least, 16days after inoculation. The GFP/LGS was detected in the sperm heads after an "in vitro" fertilization procedure, either before or after the oocyte penetration. Our results indicate that spermatozoa carrying GFP/LGS protein conserved their fertilizing ability and were also detectable after oocyte penetration. This technique will allow to develop an easy system to follow the fate of mature sperm proteins.

Failure of the interaction between presenilin 1 and the substrate of gamma-secretase to produce Abeta in insect cells

Aggregates of beta-amyloid peptide (Abeta) are the major component of the amyloid core of the senile plaques observed in Alzheimer's disease (AD). Abeta results from the amyloidogenic processing of its precursor, the amyloid precursor protein (APP), by beta- and gamma-secretase activities. If beta-secretase has recently been identified and termed BACE, the identity of gamma-secretase is still obscure. Studies with knock-out mice showed that presenilin 1 (PS1), of which mutations are known to be the first cause of inherited AD, is mandatory for the gamma-secretase activity. However, the proteolytic activity of PS1 remains a matter of debate. Here we used transfected Sf9 insect cells, a cellular model lacking endogenous beta- and/or gamma-secretase activities, to characterize the role of BACE and PS1 in the amyloidogenic processing of human APP. We show that, in Sf9 cells, BACE performs the expected beta-secretase cleavage of APP, generating C99. We also show that C99, which is a substrate of gamma-secretase, tightly binds to the human PS1. Despite this interaction, Sf9 cells still do not produce Abeta. This strongly argues against a direct proteolytic activity of PS1 in APP processing, and points toward an implication of PS1 in trafficking/presenting its substrate to the gamma-secretase.

Adenoviral and adeno-associated viral vector mediated gene transfer in the guinea pig cochlea

Peripheral sensorineural hearing loss is a very common inner ear disorder affecting nearly 10% of the population. At present there is no cure for this disorder but gene therapy has been suggested as a potentially effective method for clinical treatment in the future. Thus we investigated the effectiveness of adenoviral (Ad) and adeno-associated viral (AAV) vectors to transduce the cochlea of guinea pigs. After direct injection into the basal turn of the cochlea, we found that both Ad and AAV vectors coding for the reporter genes lacZ or GFP readily transduced spiral ganglion cells. In addition, some transgene expression was detected in the stria vascularis after AAV-GFP injection. Gene expression persisted at least 8 weeks after viral vector injection. Present findings will help to develop future gene therapy protocols in the inner ear by using Ad and AAV coding for neurotrophins such as NT-3, BDNF, GDNF and VEGF.

Neuronal transfer of the human Cu/Zn superoxide dismutase gene increases the resistance of dopaminergic neurons to 6-hydroxydopamine

Several mechanisms are thought to be involved in the progressive decline in neurons of the substantia nigra pars compacta (SNpc) that leads to Parkinson's disease (PD). Neurotoxin 6-hydroxydopamine (6-OHDA), which induces parkinsonian symptoms in experimental animals, is thought to be formed endogenously in patients with PD through dopamine (DA) oxidation and may cause dopaminergic cell death via a free radical mechanism. We therefore investigated protection against 6-OHDA by inhibiting oxidative stress using a gene transfer strategy. We overexpressed the antioxidative Cu/Zn-superoxide dismutase (SOD1) enzyme in primary culture dopaminergic cells by infection with an adenovirus carrying the human SOD1 gene (Ad-hSOD1). Survival of the dopaminergic cells exposed to 6-OHDA was 50% higher among the SOD1-producing cells than the cells infected with control adenoviruses. In contrast, no significant increased survival of (6-OHDA)-treated dopaminergic cells was observed when they were infected with an adenovirus expressing the H(2) O(2) -scavenging glutathione peroxidase (GPx) enzyme. These results underline the major contribution of superoxide in the dopaminergic cell death process induced by 6-OHDA in primary cultures. Overall, this study demonstrates that the survival of the dopaminergic neurons can be highly increased by the adenoviral gene transfer of SOD1. An antioxidant gene transfer strategy using viral vectors expressing SOD1 is therefore potentially beneficial for protecting dopaminergic neurons in PD.

A MAGE-3 peptide presented by HLA-B44 is also recognized by cytolytic T lymphocytes on HLA-B18

Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because of their tumoral specificity and because they are shared by many tumors. Antigenic peptide MEVDPIGHLY, which is encoded by MAGE-3 and is known to be presented by human leukocyte antigen (HLA)-B44, is currently being used in therapeutic vaccination trials. We report here that a cytolytic T lymphocyte (CTL) clone, which is restricted by HLA-B*1801, recognizes the same peptide and, importantly, lyzes HLA-B18 tumor cells expressing MAGE-3. These results imply that the use of peptide MEVDPIGHLY can now be extended to HLA-B18 patients. We also provide evidence that, under limiting amounts of protein MAGE-3, HLA B*1801 and B*4403 compete for binding to the peptide.

Correlation between beta-amyloid peptide production and human APP-induced neuronal death

The production of amyloid peptide (Abeta) from its precursor (APP) plays a key role in Alzheimer's disease (AD). However, the link between Abeta production and neuronal death remains elusive. We studied the biological effects associated with human APP expression and metabolism in rat cortical neurons. Human APP expressed in neurons is processed to produce Abeta and soluble APP. Moreover, human APP expression triggers neuronal death. Pepstatin A, an inhibitor of aspartyl proteases that reduces Abeta production, protects neurons from APP-induced neurotoxicity. This suggests that Abeta production is likely to be the critical event in the neurodegenerative process of AD.

Introduction to cancer gene therapy

Over the past decade, the unprecedented growth in science and technology has fueled the development of novel treatment strategies to combat disease. The creative and innovative efforts of scientists and clinicians to overcome the multitude of unforeseen obstacles to success is no better exemplified than in the field of cancer gene therapy. Since its inception, developers of cancer gene therapy have been charged with the challenge of altering basic tumor biology or, alternatively, the host responses for the purpose of tumor eradication and prevention. Several major therapeutic strategies have emerged from preclinical studies, and results from these early studies hold promise for altering the clinical outcome in a variety of malignancies. These strategies may be broadly subcategorized and range in intent from alteration of the tumor cell phenotype by replacement of defective cellular response genes (e.g., mutated or deleted tumor suppressor genes) to the enhancement of the immunological response to cancer (e.g., amplification of the cell surface antigen signature or modulation of the host response). Not surprisingly, the increasingly intricate nature of tumor biology revealed over the past several years has effectively raised the bar of success for those involved in the development of effective molecular and cancer gene therapy strategies. This, in turn, has led to the development of more complex therapies that frequently draw upon multiple disciplines in an effort to optimize treatment response.

Binding of adenovirus to its receptors in mouse astrocytes induces c-fos proto-oncogene and apoptosis

We have demonstrated that Ad.betaGal, a broadly used adenoviral vector of serotype 5, binds and induces proto-oncogene c-fos expression in quiescent cultures of mouse brain astrocytes. As observed in Northern blots, the expression of this immediate early gene is induced by viral infection in a dose-dependent manner, peaking at a multiplicity of infection (m.o.i.) of 100. The expression of c-fos is transient, being maximal after 30 min and disappearing 2 h after infection. A previously reported method was used to study the presence of receptors for adenovirus in the cellular membrane of murine astrocytes. After absorption of the virus, rabbit antibodies and 125I-protein A were used to form a sandwich on the cellular surface, and 9000 adenovirus-specific receptors were demonstrated on each astrocytic cell. Binding was temperature dependent and reached a plateau after 60 min. The specificity of c-fos induction is demonstrated by its neutralization by anti-adenovirus-specific antibodies. Although clear apoptosis cannot be demonstrated in vitro by DNA laddering, maybe due to a lack of sensitivity of the method, a statistically significant increase in caspase-3 activity is demonstrated in astrocyte cultures infected at a m.o.i. of 100 by adenovirus. Furthermore, a perfect colocalization is shown in vivo between cells infected with the Ad.betaGal vector and apoptotic astrocytes, as demonstrated by TdT-mediated dUTP nick end labeling (TUNEL) staining. The purpose of our study was to ascertain the potential for adenovirus as a gene therapy vector for neural disorders caused by astrocyte dysfunctions.

Intracellular amyloid-beta 1-42, but not extracellular soluble amyloid-beta peptides, induces neuronal apoptosis

Alzheimer disease (AD), the most frequent cause of dementia, is characterized by an important neuronal loss. A typical histological hallmark of AD is the extracellular deposition of beta-amyloid peptide (A beta), which is produced by the cleavage of the amyloid precursor protein (APP). Most of the gene mutations that segregate with the inherited forms of AD result in increasing the ratio of A beta 42/A beta 40 production. A beta 42 also accumulates in neurons of AD patients. Altogether, these data strongly suggest that the neuronal production of A beta 42 is a critical event in AD, but the intraneuronal A beta 42 toxicity has never been demonstrated. Here, we report that the long term expression of human APP in rat cortical neurons induces apoptosis. Although APP processing leads to production of extracellular A beta 1-40 and soluble APP, these extracellular derivatives do not induce neuronal death. On the contrary, neurons undergo apoptosis as soon as they accumulate intracellular A beta 1-42 following the expression of full-length APP or a C-terminal deleted APP isoform. The inhibition of intraneuronal A beta 1-42 production by a functional gamma-secretase inhibitor increases neuronal survival. Therefore, the accumulation of intraneuronal A beta 1-42 is the key event in the neurodegenerative process that we observed.

Nf2 gene inactivation in arachnoidal cells is rate-limiting for meningioma development in the mouse

Biallelic NF2 gene inactivation is common in sporadic and in neurofibromatosis type 2 (NF2)-related meningiomas. We show that, beginning at four months of age, thirty percent of mice with arachnoidal cell Cre-mediated excision of Nf2 exon 2 developed a range of meningioma subtypes histologically similar to the human tumors. Additional hemizygosity for p53 did not modify meningioma frequency or progression suggesting that Nf2 and p53 mutations do not synergize in meningeal tumorigenesis. This first mouse model initiated with a genetic lesion found in human meningiomas provides a powerful tool for investigating tumor progression and for the preclinical evaluation of therapeutic interventions.

Targeted gene therapy for the treatment of cardiac dysfunction

Congestive heart failure (CHF), one of the leading cardiovascular disorders in developed countries, remains a significant therapeutic challenge. Efficacious therapies are few, and the incidence of CHF and associated death rates continue to rise. An interest in the novel therapeutic approach of gene therapy for the treatment of CHF has emerged. Essential elements of successful gene therapy include an appropriate vector for delivering and expressing the gene within the target cell, an optimal protocol for delivery of the gene, and the identification of relevant pathways and molecular targets. Interest in gene therapy for CHF has been directed towards improving cardiomyocyte function through optimization of calcium homeostasis and beta-adrenoreceptor function, and preclinical studies have shown encouraging results. This review will discuss the vectors and mechanisms of gene delivery as well as potential molecular targets for the treatment of CHF.

The production of a new MAGE-3 peptide presented to cytolytic T lymphocytes by HLA-B40 requires the immunoproteasome

By stimulating human CD8(+) T lymphocytes with autologous dendritic cells infected with an adenovirus encoding MAGE-3, we obtained a cytotoxic T lymphocyte (CTL) clone that recognized a new MAGE-3 antigenic peptide, AELVHFLLL, which is presented by HLA-B40. This peptide is also encoded by MAGE-12. The CTL clone recognized MAGE-3--expressing tumor cells only when they were first treated with IFN-gamma. Since this treatment is known to induce the exchange of the three catalytic subunits of the proteasome to form the immunoproteasome, this result suggested that the processing of this MAGE-3 peptide required the immunoproteasome. Transfection experiments showed that the substitution of beta5i (LMP7) for beta5 is necessary and sufficient for producing the peptide, whereas a mutated form of beta5i (LMP7) lacking the catalytically active site was ineffective. Mass spectrometric analyses of in vitro digestions of a long precursor peptide with either proteasome type showed that the immunoproteasome produced the antigenic peptide more efficiently, whereas the standard proteasome more efficiently introduced cleavages destroying the antigenic peptide. This is the first example of a tumor-specific antigen exclusively presented by tumor cells expressing the immunoproteasome.

Transrectal gene therapy of the prostate in the canine model

Direct transrectal delivery of therapeutic genes utilizing adenoviral vectors for advanced prostate cancer may offer effective treatment at the molecular level. Large animal models to assess feasibility and the intraprostatic and systemic dissemination patterns of these vectors have not been reported. For these studies, a replication-deficient (E1(-)/E3(-)) recombinant adenovirus (AdRSVlacZ) expressing bacterial beta-galactosidase (beta-gal) was delivered under transrectal ultrasound guidance. Two prostate biopsies, followed by concurrent injection of 4.8 x 10(9) pfu of the adenoviral vector divided into either 1 or 2 mL of diluent, were performed (n=4). Swabs of the rectum, sputum, and urine were collected and after 72 hours, the animals were sacrificed. Specimens were assayed for the presence of virus and beta-gal activity. Rectal swabs were transiently positive, whereas urine and sputum samples showed no detectable vector throughout the experiment. Beta-gal activity was observed at the prostate injection sites with detectable activity noted up to 7.5 mm away from the injection site. Systemic dissemination was observed regardless of the injected volume. In conclusion, transrectal prostate biopsy with concurrent prostate injection is a feasible method to deliver therapeutic adenoviral vectors for the treatment of prostate cancer; however, systemic distribution and temporary rectal shedding of virus should be anticipated.

Adenoviral retrograde gene transfer in motoneurons is greatly enhanced by prior intramuscular inoculation with botulinum toxin

Retrograde axonal transport of recombinant adenoviral vectors has been used successfully to deliver genes to motoneurons in rodents after injection of the vectors into muscles. However, only a small proportion of motoneurons take up and retrogradely transport adenoviral particles, limiting the value of this gene delivery method for the treatment of motor neuron diseases (MNDs). Here we validate a new pharmacological approach for enhancing motoneuronal gene transfer after intramuscular injection of recombinant adenoviruses. We injected botulinum neurotoxin A (BoNT) into muscles of normal C57BL/6 mice and transgenic mice expressing the G93A mutation in the superoxide dismutase 1 gene (SOD1-G93A mutation, a model of amyotrophic lateral sclerosis) several days before inoculation with adenoviruses. Treatment with BoNT significantly enhanced gene transfer to motoneurons innervating the injected muscles. Modifications in motoneuron transduction appear to be a consequence of toxin-induced nerve sprouting at the end plates. These findings have major implications for devising protocols for preclinical and clinical studies using intramuscular injection of retrogradely transported gene vectors.

Increasing local levels of IGF-I mRNA expression using adenoviral vectors does not alter oligodendrocyte remyelination in the CNS of aged rats

IGF-I, a growth factor that contributes to developmental myelination, shows increased levels of expression within experimental models of remyelination. The pattern of IGF-I mRNA expression changes with the rate of remyelination, with peak levels of expression occurring earlier during rapid remyelination in young adult rats compared to the slower remyelination in old adult rats. In this study we have attempted to accelerate remyelination in old adult rats by using an IGF-expressing adenoviral vector (IGF-I-Ad) to bring forward the timing of peak level of IGF-I expression. Following injection of IGF-I-Ad into focal areas of lysolecithin-induced demyelination in the spinal white matter of old adult rats we created levels of IGF-I mRNA expression at 10 days that were considerably higher than those normally occurring at this time and more similar to those in young animals. However, despite the elevated levels of IGF-I mRNA expression there was no significant change in the extent of oligodendrocyte remyelination compared to saline controls or animals injected with an adenoviral vector expressing LacZ (NT-LacZ-Ad). There was a small increase in Schwann cell remyelination in IGF-I-Ad- and NT-LacZ-Ad-injected animals compared to saline controls. These results indicate that changing the levels of IGF-I directly within demyelinating lesions undergoing remyelination is not sufficient to alter remyelination and that the proremyelinating effects of systemically delivered IGF-I are unlikely to be due to direct effects on the oligodendrocyte lineage.

Transposition of the thyroid iodide uptake and organification system in nonthyroid tumor cells by adenoviral vector-mediated gene transfers

Radioactive iodine (131I) is routinely used for the treatment of differentiated thyroid cancers. Attempts have been made to enlarge this therapeutic strategy to nonthyroid tumors by coupling radioactive iodide administration with transfer of the sodium iodide symporter (NIS) gene into target cells, for example with an adenoviral vector (AdNIS). Although efficient iodide uptake was achieved in the tumors treated with AdNIS, no therapeutic effect could be observed with 131I, most probably because the iodide retention time in the target cells was short. To circumvent this problem, we propose to organify the iodide taken up, as it occurs in the thyroid. We constructed a recombinant adenovirus encoding the human thyroperoxidase (TPO) gene under the control of the cytomegalovirus early promoter (AdTPO). Infection of nonthyroid tumor cells with this virus led to production of an enzymatically active protein. A significant increase in iodide organification could be observed in cells coinfected with both AdNIS and AdTPO in the presence of exogenous hydrogen peroxide. However, the levels of iodide organification obtained were too low to significantly increase the iodide retention time in the target cells.