Antisense oligonucleotides are being evaluated in clinical trials as novel therapeutic agents. To further improve the properties of antisense oligonucleotides, we have designed mixed-backbone oligonucleotides (MBOs) that contain phosphorothioate segments at the 3 and 5 ends and have a modified oligodeoxynucleotide or oligoribonucleotide segment located in the central portion of the oligonucleotide. Some of these MBOs indicate improved properties compared with phosphorothioate oligodeoxynucleotides with respect to affinity to RNA, RNase H activation, and anti-HIV activity. In addition, more acceptable pharmacological, in vivo degradation and pharmacokinetic profiles were obtained with these MBOs.Synthetic oligonucleotides (oligos) complementary to messenger RNA have shown promise as therapeutic agents for various diseases (1). Phosphorothioate oligodeoxynucleotides (PSoligos) have been studied intensively in both in vitro and in vivo models, and clinical trials in humans are underway (2).Although PS-oligos continue to show promising results as first generation antisense oligos, they have certain limitations (2). Toxicity studies of PS-oligos in mice, rats, monkeys, and humans have shown some dose-dependent side effects (2). In mice and rats, these side effects include thrombocytopenia, elevation of liver transaminases, hyperplasia of reticuloendothelial cells in various organs, and renal tubular changes (2, 3). In monkeys, the side effects observed are activation of complement (4) and prolongation of activated partial thromboplastin time (aPTT; refs. 2 and 5). These side effects may be caused by the PS-oligos or by their in vivo metabolites. Because similar side effects have been observed after administration of dextran sulfate (2, 6), the inference is that these side effects are caused by the polyanionic nature of PS-oligos and are not nucleotide-sequence-specific. In addition, certain conditions (e.g., splenomegaly) may be caused by a sequence-dependent mitogenic response leading to cytokine induction (2, 7). The aim of the present study was to design less polyanionic oligos that would still be biologically active as antisense agents but less immune stimulatory than the original oligos. A related aim was to retain control of degradation in vivo and therefore generate a favorable pharmacological and safety profile. MATERIALS AND METHODSSynthesis and Analysis of Oligonucleotides. The structures of oligos used in the present study are illustrated in Table 1. The synthesis of oligos was carried out on a 15-mol scale (Biosearch 8900 DNA Synthesizer) or on a 1-mmol scale (Pharmacia OligoPilot II Synthesizer) using appropriate nucleoside phosphoramidites (8). Oligos 1, 9, 10, and 11 were synthesized and purified as reported (8). Oligos 2, 4, 6, 8, and 15 were synthesized in a three-step reaction sequence. First, the 3Ј end was prepared using deoxynucleoside phosphoramidites. The central region was next synthesized using 2Ј-Omethylribonucleoside phosphoramidites, and finally, the 5Ј end was prepared from deoxyn...

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Codon usage optimization of human immunodeficiency virus type 1 (HIV-1) structural genes has been shown to increase protein expression in vitro as well as in the context of DNA vaccines in vivo; however, all optimized genes reported thus far are derived from HIV-1 (group M) subtype B viruses. Here, we report the generation and biological characterization of codon usage-optimized gag, pol, env (gp160, gp140, gp120), and nef genes from a primary (nonrecombinant) HIV-1 subtype C isolate. After transfection into 293T cells, optimized subtype C genes expressed one to two orders of magnitude more protein (as determined by immunoblot densitometry) than the corresponding wild-type constructs. This effect was most pronounced for gp160, gp140, Gag, and Pol (>250-fold), but was also observed for gp120 and Nef (45- and 20-fold, respectively). Optimized gp160- and gp140-derived glycoproteins were processed, incorporated into virus particles, and mediated virus entry when expressed in trans to complement an env-minus HIV-1 provirus. Mice immunized with optimized gp140 DNA developed antibody as well as CD4+ and CD8+ T cell immune responses that were orders of magnitude greater than those of mice immunized with wild-type gp140 DNA. These data confirm and extend previous studies of codon usage optimization of HIV-1 genes to the most prevalent group M subtype. Our panel of matched optimized and wild-type subtype C genes should prove valuable for studies of protein expression and function, the generation of subtype-specific immunological reagents, and the production of DNA-based sub-unit vaccines directed against a broader spectrum of viruses.

Sperm protein 17 (Sp17) is an antigenic protein highly expressed in spermatozoa. Sp17 expression was demonstrated recently in multiple myeloma, suggesting that it may be a novel cancer-testis antigen. Expression of Sp17 mRNA and protein was examined in human ovarian tumors.

Dendritic cells (DCs) are pivotal antigen-presenting cells for regulating immune responses. A major focus of contemporary vaccine research is the genetic modification of DCs to express antigens or immunomodulatory molecules, utilizing a variety of viral and nonviral vectors, to induce antigen-specific immune responses that ameliorate disease states as diverse as malignancy, infection, autoimmunity, and allergy. The present study has evaluated adeno-associated virus (AAV) type 2 as a vector for ex vivo gene transfer to human peripheral blood monocyte (MO)-derived DCs. AAV is a nonpathogenic parvovirus that infects a wide variety of human cell lineages in vivo and in vitro, for long-term transgene expression without requirements for cell proliferation. The presented data demonstrate that recombinant AAV (rAAV) can efficiently transduce MOs as well as DCs generated by MO culture with granulocyte-macrophage colony-stimulating factor plus interleukin in vitro. rAAV transgene expression in MO-derived DCs could be enhanced by etoposide, previously reported to enhance AAV gene expression. rAAV transduction of freshly purified MO followed by 7 days of culture with cytokines to generate DCs, and subsequent sorting for coexpression of DC markers CD1a and CD40, showed robust transgene expression as well as evidence of nuclear localization of the rAAV genome in the DC population. Phenotypic analyses using multiple markers and functional assays of one-way allogeneic mixed leukocyte reactions indicated that rAAV-transduced MO-derived DCs were as equivalent to nontransduced DCs. These results support the utility of rAAV vectors for future human DC vaccine studies.Dendritic cells (DCs) are potent antigen-presenting cells (APC) for initiating T-cell immunity, due to their ability to take up and process antigens for presentation by major histocompatibility complex (MHC) class I and class II molecules, migrate to T-cell areas of lymphoid tissues, and present antigen in conjunction with the appropriate T-cell costimulatory molecules and cytokines (reviewed in references 3, 4, 44, and 51). DCs can be manipulated ex vivo to express antigens in order to generate effective vaccines for a variety of immunotherapy applications. In the simpler approaches, DCs are pulsed by incubation with purified proteins, microbial or tumor cell lysates, synthetic MHC-binding peptides, or crude peptides eluted from tumor cells, all of which have shown promising results, although the persistence of antigens on pulsed DCs is of relatively short duration (4, 44, 51). Alternatively, the transfer of genes encoding antigens into DCs offers the advantages of sustained antigen expression and a broader spectrum of MHC peptide epitopes presented by DCs and allows modulation of DC receptors and cytokine secretion to further finetune the immune response (3,4,44,51). Both nonviral and viralvector-mediated gene transfer have been used for DC-based immunotherapy in animal models and human clinical trials, with the majority of viral-mediated DC transductions employing r...

Peritoneal compartmentalization of advanced stage ovarian cancer provides a rational scenario for gene therapy strategies. Several groups are exploring intraperitoneal administration of adenoviral (Ad) vectors for this purpose. We examined in vitro gene transfer in the presence of ascites fluid from ovarian cancer patients and observed significant inhibition of Ad-mediated gene transfer. The inhibitory activity was not identified as either complement or cellular factors, but depletion of IgG from ascites removed the inhibitory activity, implicating neutralizing anti-Ad antibodies. A wide range of preexisting anti-Ad antibody titers in patient ascites fluid was measured by ELISA. Western blot analysis demonstrated that the antibodies were directed primarily against the Ad fiber protein. To circumvent inhibition by neutralizing antibodies, a genetically modified adenoviral vector was tested. The Ad5Luc.RGD vector has an Arg-Gly-Asp (RGD) peptide sequence inserted into the fiber knob domain and enters cells through a nonnative pathway. Compared with the conventional Ad5 vector, Ad5Luc.RGD directed efficient gene transfer to cell lines and primary ovarian cancer cells in the presence of ascites fluid containing high-titer neutralizing anti-Ad antibodies. These results suggest that such modified Ad vectors will be needed to achieve efficient gene transfer in the clinical setting.

Angiogenesis is characteristic of solid tumor growth and a surrogate marker for metastasis in many human cancers. Inhibition of tumor angiogenesis using antiangiogenic drugs and gene transfer approaches has suggested the potential of this form of therapy in controlling tumor growth. However, for long-term tumor-free survival by antiangiogenic therapy, the factors controlling tumor neovasculature need to be systemically maintained at stable therapeutic levels. Here we show sustained expression of the antiangiogenic factors angiostatin and endostatin as secretory proteins by recombinant adeno-associated virus 2 (rAAV)-mediated gene transfer. Both vectors provided significant protective efficacy in a mouse tumor xenograft model. Stable transgene persistence and systemic levels of both angiostatin and endostatin were confirmed by in situ hybridization of the vector-injected tissues and by serum ELISA measurements, respectively. Whereas treatment with rAAV containing either endostatin or angiostatin alone resulted in moderate to significant protection, the combination of endostatin and angiostatin gene transfer from a single vector resulted in a complete protection. These data suggest that AAV-mediated long-term expression of both endostatin and angiostatin may have clinical utility against recurrence of cancers after primary therapies and may represent rational adjuvant therapies in combination with radiation or chemotherapy.

Background: Mesothelin is an attractive target for cancer immunotherapy due to its restricted expression in normal tissues and high level expression in several tumor types including ovarian and pancreatic adenocarcinomas. Three mesothelin transcript variants have been reported, but their relative expression in normal tissues and tumors has been poorly characterized. The goal of the present study was to clarify which mesothelin transcript variants are commonly expressed in human tumors.