Current understanding of key transcription factors regulating angiogenesis is limited. Here we show that RNA-cleaving phosphodiester-linked DNA-based enzymes (DNAzymes), targeting a specific motif in the 5' untranslated region of early growth response (Egr-1) mRNA, inhibit Egr-1 protein expression, microvascular endothelial cell replication and migration, and microtubule network formation on basement membrane matrices. Egr-1 DNAzymes blocked angiogenesis in subcutaneous Matrigel plugs in mice, an observation that was independently confirmed by plug analysis in Egr-1-deficient animals, and inhibited MCF-7 human breast carcinoma growth in nude mice. Egr-1 DNAzymes suppressed tumor growth without influencing body weight, wound healing, blood coagulation or other hematological parameters. These agents inhibited endothelial expression of fibroblast growth factor (FGF)-2, a proangiogenic factor downstream of Egr-1, but not that of vascular endothelial growth factor (VEGF). Egr-1 DNAzymes also repressed neovascularization of rat cornea. Thus, microvascular endothelial cell growth, neovascularization, tumor angiogenesis and tumor growth are processes that are critically dependent on Egr-1.

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Abstract-Early growth response factor-1 (Egr-1) controls the expression of a growing number of genes involved in the pathogenesis of atherosclerosis and postangioplasty restenosis. Egr-1 is activated by diverse proatherogenic stimuli. As such, this transcription factor represents a key molecular target in efforts to control vascular lesion formation in humans.In this study, we have generated DNAzymes targeting specific sequences in human EGR-1 mRNA. These molecules cleave in vitro transcribed EGR-1 mRNA efficiently at preselected sites, inhibit EGR-1 protein expression in human aortic smooth muscle cells, block serum-inducible cell proliferation, and abrogate cellular regrowth after mechanical injury in vitro. These DNAzymes also selectively inhibit EGR-1 expression and proliferation of porcine arterial smooth muscle cells and reduce intimal thickening after stenting pig coronary arteries in vivo. Key Words: catalytic DNA Ⅲ transcription factors Ⅲ early growth response factor-1 Ⅲ stenting Ⅲ gene therapy T he capacity to selectively target specific mRNA sequences with catalytic molecules composed of DNA provides immense potential to broaden our understanding of the roles of specific mediators in normal and pathologic settings. Catalytic DNA can be used to cleave the phosphodiester linkage between virtually any unpaired purine and paired pyrimidine, selectivity being conferred by the nucleotide sequences of the hybridizing arms. These next-generation antisense oligonucleotides are extremely specific and easy to synthesize and have low toxicity, because they do not require phosphorothioate or other backbone modifications to confer nuclease resistance. DNAzyme biotechnology has practical therapeutic implications as a new category of genesuppression agents in pathophysiological settings.Stenting of coronary atherosclerotic lesions has revolutionized the treatment of cardiovascular disease in the last 5 years, after two landmark trials demonstrating a reduction in restenosis relative to coronary balloon angioplasty in comparable vessels.

Neointima formation is a characteristic feature of common vascular pathologies, such as atherosclerosis and post-angioplasty restenosis, and involves smooth muscle cell proliferation. Determination of whether the bZIP transcription factor c-Jun plays a direct regulatory role in arterial lesion formation, or indeed in other disease, has been hampered by the lack of a potent and specific pharmacological inhibitor. c-Jun is poorly expressed in the uninjured artery wall and transiently induced following arterial injury in animal models. Here we generated a gene-specific DNAzymetargeting c-Jun. We show that c-Jun protein is expressed in human atherosclerotic lesions. Dz13, a catalytically active c-Jun DNAzyme, cleaved c-Jun RNA and inhibited inducible c-Jun protein expression in vascular smooth muscle cells. Dz13 blocked vascular smooth muscle cell proliferation with potency exceeding its exact non-catalytic antisense oligodeoxynucleotide equivalent. Moreover, Dz13 abrogated smooth muscle cell repair following scraping injury in vitro and intimal thickening in injured rat carotid arteries in vivo. These studies demonstrate the positive influence on neointima formation by c-Jun and the therapeutic potential of a DNAzyme controlling its expression.The initiating event in the pathogenesis of atherosclerosis and restenosis following angioplasty is injury to cells in the artery wall (1). Injury stimulates signaling and transcriptional pathways in vascular smooth muscle cells, stimulating their migration and proliferation, and the eventual formation of a neointima. c-Jun, a prototypical member of the basic region-leucine zipper protein family, is transiently induced following arterial injury in animal model (2-4). c-Jun forms both homodimers and heterodimers with other bZIP proteins to form the AP-1 transcription factor. While investigations over the last decade have linked AP-1 with proliferation, tumorigenesis and apoptosis, AP-1 has also been implicated in tumor suppression and cell differentiation (5). Recent reports indicate that c-Jun NH 2 -terminal kinase/stressactivated protein kinase (JNK), 1 an upstream activator of c-Jun and numerous other transcription factors, is expressed by smooth muscle cells in human and rabbit atherosclerotic plaques (6, 7) and that dominant negative JNK inhibits neointima formation after balloon injury (8). c-Jun, however, has not been localized in human atherosclerotic lesions nor has it been shown to play a role in arterial repair after injury.Investigation of the precise regulatory role of c-Jun in the injured artery wall, or indeed in other pathologic settings, has been hampered by the lack of a specific pharmacological inhibitor.DNAzymes represent a new class of gene-targeting agent with specificity conferred by the sequence of nucleotides in the two arms flanking a catalytic core, with advantages over ribozymes of substrate specificity and stability (9, 10). DNAzymes specific for c-Jun would be useful as molecular determinants of c-Jun biological function. To date, neither c-Jun no...

Conventional anti-inflammatory strategies induce multiple side effects, highlighting the need for novel targeted therapies. Here we show that knockdown of the basic-region leucine zipper protein, c-Jun, by a catalytic DNA molecule, Dz13, suppresses vascular permeability and transendothelial emigration of leukocytes in murine models of vascular permeability, inflammation, acute inflammation and rheumatoid arthritis. Treatment with Dz13 reduced vascular permeability due to cutaneous anaphylactic challenge or VEGF administration in mice. Dz13 also abrogated monocyte-endothelial cell adhesion in vitro and abolished leukocyte rolling, adhesion and extravasation in a rat model of inflammation. Dz13 suppressed neutrophil infiltration in the lungs of mice challenged with endotoxin, a model of acute inflammation. Finally, Dz13 reduced joint swelling, inflammatory cell infiltration and bone erosion in a mouse model of rheumatoid arthritis. Mechanistic studies showed that Dz13 blocks cytokine-inducible endothelial c-Jun, E-selectin, ICAM-1, VCAM-1 and VE-cadherin expression but has no effect on JAM-1, PECAM-1, p-JNK-1 or c-Fos. These findings implicate c-Jun as a useful target for anti-inflammatory therapies.

Smooth muscle cell (SMC) proliferation and migration are key processes that occur in the pathogenesis of atherosclerosis and post-angioplasty restenosis. In the present study, we designed locked nucleic acid (LNA)-modified DNAzymes targeting a specific region spanning the translational start site of human EGR-1, an immediate-early gene, wherein two of the nucleotides in each of the 9+9 hybridizing arms of the DNAzyme were substituted with LNA monomers. In vitro cleavage experiments revealed that the LNA- modified DNAzyme (LzF4) cleaved a 32P-labelled 388 nt EGR-1 transcript with greater efficacy than its native unmodified phosphodiester counterpart, DzF. The scrambled versions of these molecules, LzF4SCR and DzFSCR, did not display any ability to cleave the transcript. Western blot analysis revealed that both active molecules abrogated serum-inducible EGR-1 protein expression in primary human aortic SMCs and inhibited serum-inducible SMC proliferation in a dose-dependent and non-toxic manner. SMC proliferation was inhibited by >50% with LzF4 at concentrations as low as 20 nM, whereas inhibition by DzF at this concentration was not evident. Finally, LzF4 and DzF inhibited SMC regrowth from the wound edge after mechanical injury in vitro. In contrast, neither DzFSCR nor LzF4SCR had any influence on EGR-1 protein expression, SMC proliferation or regrowth. These findings provide the first functional demonstration of LNA-modified DNAzyme efficacy in a biological setting of any kind. These studies also demonstrate that LNA modification increases DNAzyme potency without necessarily compromising specificity.

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Abstract-Sp1, the first identified and cloned transcription factor, regulates gene expression via multiple mechanisms including direct protein-DNA interactions, protein-protein interactions, chromatin remodeling, and maintenance of methylation-free CpG islands. Sp1 is itself regulated at different levels, for example, by glycosylation, acetylation, and phosphorylation by kinases such as the atypical protein kinase C-. Although Sp1 controls the basal and inducible regulation of many genes, the posttranslational processes regulating its function and their relevance to pathology are not well understood. Here we have used a variety of approaches to identify 3 amino acids (Thr668, Ser670, and Thr681) in the zinc finger domain of Sp1 that are modified by PKC-and have generated novel anti-peptide antibodies recognizing the PKC--phosphorylated form of Sp1. Angiotensin II, which activates PKC-phosphorylation (at Thr410) via the angiotensin II type 1 receptor, stimulates Sp1 phosphorylation and increases Sp1 binding to the platelet-derived growth factor-D promoter. All 3 residues in Sp1 (Thr668, Ser670, and Thr681) are required for Sp1-dependent platelet-derived growth factor-D activation in response to angiotensin II. Immunohistochemical analysis revealed that phosphorylated Sp1 is expressed in smooth muscle cells of human atherosclerotic plaques and is dynamically expressed together with platelet-derived growth factor-D in smooth muscle cells of the injured rat carotid artery wall. This study provides new insights into the regulatory mechanisms controlling the PKC--phospho-Sp1 axis and angiotensin II-inducible gene expression. (Circ Res. 2008;102:e38-e51.)