E2F decoy oligodeoxynucleotides effectively inhibit growth of human tumor cells

Role of Oct4-Sox2 complex decoy oligodeoxynucleotides strategy on reverse epithelial to mesenchymal transition (EMT) induction in HT29-ShE encompassing enriched cancer stem-like cells

Cancer stem cells are commonly tolerant toward chemotherapy and radiotherapy. Oct4 and Sox2 transcription factors are shown to be overexpressed in various cancers. At the current research, inhibition of Oct4 and Sox2 transcription factors was performed through application of decoy oligodeoxynucleotides (ODNs) strategy via repressing stemness properties in HT29-ShE cells encompassing enriched cancer stem-like cells. Designed Oct4-Sox2 complex decoy ODNs were transfected into HT29-ShE cells with Lipofectamine reagent. At the next step, ODNs efficiency transfection and subcellular localization were determined via flow cytometry and fluorescence microscopy, respectively. Further investigations such as cell proliferation and apoptosis analysis, colonosphere formation, invasion and migration, and real-time PCR assays were also carried out. Obtained results shed light on the fact that the designed complex decoys were effectively transfected into HT29-ShE cells, and they were found to be localized in subcellular compartments. Oct4-Sox2 decoy ODNs led to decreased cell viability, arresting the cell cycle in G0/G1 phases, increasing apoptosis, inhibition of migration/invasion and colonosphere formation ability of HT29-ShE cells in comparison with control and scramble groups. Furthermore, Oct4-Sox2 complex decoy could modulate the MET process via alteration of mRNA expression of downstream genes. It could be concluded that application of Oct4-Sox2 transcription factor decoy strategy in cells with stemness potential could lead to inhibiting the cell growth and triggering differentiation. Therefore, this technique could be applied along with usual remedies (chemotherapy and radiotherapy) as high potential method for treating cancer.

Simultaneous targeted inhibition of Sox2-Oct4 transcription factors using decoy oligodeoxynucleotides to repress stemness properties in mouse embryonic stem cells

Transcriptional master regulators like Sox2 and Oct4, which are expressed in various human tumors, have been shown to cause tumor growth promotion as well as epithelial dysplasia by means of interfering with progenitor cell differentiation. In order to investigate the potential of Sox2-Oct4 transcription factor decoy (TFD) strategy for differentiation therapy, mouse embryonic stem cells (mESCs) were used in this study as a model of cancer stem cells (CSCs). Sox2-Oct4 complex decoy ODNs (cd-ODNs) were designed according to their elements in the promoter region of Sox2 gene. DNA-protein interactions between decoy ODNs and their corresponding proteins were examined by electrophoretic mobility shift assay (EMSA). Then, decoy and scrambled ODNs were transfected into mESCs with lipofectamine under 2 inhibitors (2i) conditions. Fluorescence and confocal microscopy, cell viability, cell cycle and apoptosis analysis, alkaline phosphatase, embryoid body formation assay, and real-time PCR were used to conduct further investigations. EMSA data showed that Sox2-Oct4 decoy ODNs bound specifically to their recombinant proteins. The results revealed that the synthesized complex decoy can concomitantly target Sox2 and Oct4, which subsequently represses the stemness properties of mESCs compared to controls through decreasing cell viability, arresting cell cycle in G₀ /G₁ phases, inducing apoptosis, and modulating differentiation in mESCs despite the presence of 2i/LIF in cell culture. While cd-ODN strategy seems to offer great promise for cancer therapy, further studies are still required to put this powerful investigative tool in practice for a wide range of human cancers.

E2F1 silencing inhibits migration and invasion of osteosarcoma cells via regulating DDR1 expression

In the present study, knockdown of E2F1 impaired the migration and invasion of osteosarcoma cells. Further analysis showed that E2F1 knockdown decreased the expression of discoidin domain receptor 1 (DDR1) which plays a crucial role in many fundamental processes such as cell differentiation, adhesion, migration and invasion. Luciferase and ChIP assays confirmed that E2F1 silencing attenuated the expression of DDR1 through disrupting E2F1-mediated transcription of DDR1 in osteosarcoma cells. Similarly with the effect of E2F1 silencing, DDR1 knockdown weakened the migratory and invasive capabilities of osteosarcoma cells; while overexpression of DDR1 resulted in a significant increase of cell motility and invasiveness, even after knocking down E2F1. Interestingly, inactivation of E2F1/DDR1 pathway by shRNA weakened STAT3 signaling and subsequently suppressed the epithelial-mesenchymal transition (EMT) of osteosarcoma cells, as shown with decreased vimentin, MMP2, MMP9, and increased E-cadherin. Consistently, high expressions of E2F1 and DDR1 observed in osteosarcoma tissues were related to TNM stage and metastasis. In addition, high level of E2F1 or DDR1 was associated with poor prognosis in osteosarcoma patients. These results suggest that E2F1/DDR1/STAT3 pathway is critical for malignancy of osteosarcoma, which may provide a novel prognostic indicator or approach for osteosarcoma therapy.

Transcription factor decoy: a pre-transcriptional approach for gene downregulation purpose in cancer

Gene therapy as a therapeutic approach has been the dream for many scientists around the globe. Many strategies have been proposed and applied for this purpose, yet the void for a functional safe method is still apparent. Since most of the diseases are caused by undesirable upregulation (oncogenes) or downregulation (tumor suppressor genes) of genes, major gene therapy's techniques affect gene expression. Most of the methods are used in post-transcriptional level such as RNA inhibitory (RNAi) and splice-switching oligonucleotides (SSOs). RNAi blocks messenger RNA (mRNA) translation by mRNA degradation or interruption between attachments of mRNA with ribosomes' subunits. However, one of the novel methods is the usage of transcription factor targeted decoys. DNA decoys are the new generation of functional gene downregulatory oligonucleotides which compete with specific binding sites of transcription factors. Considering the exponential growth of this technique in both in vitro and in vivo studies, in this paper, we aim to line out the description, design, and application of decoys in research and therapy.

Transcription factor decoy against stem cells master regulators, Nanog and Oct-4: a possible approach for differentiation therapy

Transcription factor decoys (TFDs) are exogenous oligonucleotides which can compete by cis-elements in promoters or enhancers for binding to TFs and downregulating gene expression in a specific manner. It is believed that tumor mass originates from cancer stem cells (CSCs) which the same with embryonic stem cells (ESCs) have the properties of both pluripotency and self-renewal (stemness). Many transcription factors such as Nanog, Oct-4, Sox2, Klf4, and Sall4 act as master regulators in the maintenance of stemness in both cell types. Differentiation therapy is based on this theory that by differentiation of CSCs, tumor mass can be eliminated with common cancer therapy methods. To our knowledge, the present study is the first report of a TFD approach against master regulator of stemness, Nanog, Oct-4, and Klf4, for downregulation purposes in P19 embryonic carcinoma stem cell. Different simple and complex decoys against Nanog, OCT-4, Sox2, and Klf4 were designed and used for this purpose. The results showed that the applied decoys especially Nanog-specific decoy decreased the expression of downstream genes.

Nucleic acid-based approaches to STAT inhibition

Silencing of abnormally activated genes can be accomplished in a highly specific manner using nucleic acid based approaches. The focus of this review includes the different nucleic acid based inhibition strategies such as antisense oligodeoxynucleotides, small interfering RNA (siRNA), dominant-negative constructs, G-quartet oligonucleotides and decoy oligonucleotides, their mechanism of action and the effectiveness of these approaches to targeting the STAT (signal transducer and activator of transcription) proteins in cancer. Among the STAT proteins, especially STAT3, followed by STAT5, are the most frequently activated oncogenic STATs, which have emerged as plausible therapeutic cancer targets. Both STAT3 and STAT5 have been shown to regulate numerous oncogenic signaling pathways including proliferation, survival, angiogenesis and migration/invasion.

Suppression of cell proliferation and collagen production in cultured human hypertrophic scar fibroblasts by Sp1 decoy oligodeoxynucleotide

Hypertrophic scars are characterized by the abnormal proliferation of fibroblasts and an overproduction of collagen. The Sp1 transcription factor is involved in the stimulation of collagen synthesis. A decoy oligonucleotide (ODN) targeting Sp1 was designed and transfected into hypertrophic scar fibroblasts (HSFs) cells using cationic liposomes. The transfection efficiency was determined by flow cytometry and was observed to be 85±7% (n=5). Specific binding of the Sp1 decoy ODN was monitored with an electrophoretic mobility shift assay (EMSA). Following transfection with the decoy ODN to Sp1, cell viability and cell proliferation, which were examined by the cell counting kit WST‑8, were decreased by 80% compared with untreated cells. Transforming growth factor‑β (TGF‑β) mRNA and collagen mRNA expression were also reduced by 48% in the transfection decoy ODN group. The cell viability of HSFs after 48 h of transfection with 25, 50, 100 and 150 nM Sp1 decoy ODN was 0.9331±0.0203, 0.7479±0.0868, 0.577±0.0347 and 0.4703±0.0147, respectively. The 100 nM dose of the Sp1 decoy ODN inhibited the expression of types I and III collagen by 32 and 28%, respectively (both P<0.01). TGF‑β mRNA expression was also effectively suppressed by the 100 nM Sp1 decoy ODN (P<0.01). The Sp1 decoy ODN inhibited cell proliferation and the expression of types I and III collagen. Therefore, Sp1 decoy ODNs may be a promising tool for developing and testing novel therapeutic applications for treating hypertrophic scars.

The inhibitory effect of chimeric decoy oligodeoxynucleotide against NF-κB and Sp1 in renal interstitial fibrosis

The pathophysiology of chronic renal disease is characterized by a progressive loss of renal function and deposition of the extracellular matrix, leading to widespread tissue fibrosis. Much of the matrix in chronic renal disease is synthesized by interstitial myofibroblasts, recruited from resident fibroblasts and circulating precursors. These changes are believed to be derived from epithelial-mesenchymal transition (EMT) of tubuloepithelial cells. To develop a novel therapeutic approach for treating renal fibrosis, we examined the simultaneous inhibition of the transcription factors NF-κB and Sp1 in a mouse model of unilateral ureteral obstruction (UUO). To simultaneously inhibit both NF-κB and Sp1, we developed chimeric (Chi) decoy oligodeoxynucleotide (ODN) which contained binding sequences for both NF-κB and Sp1 in a single decoy molecule to enhance the effective use of decoy ODN strategy. Chi decoy ODN significantly attenuated tubulointerstitial fibrosis in a mouse model of UUO compared to scrambled decoy ODN, as demonstrated by the reduced interstitial volume, macrophage infiltration, and fibrosis-related gene expression. Interestingly, Chi decoy ODN also regulated EMT-related gene expression, leading to the inhibition of renal fibrotic changes in vivo and in vitro. The present study demonstrates the feasibility of Chi decoy ODN treatment for preventing renal fibrosis and EMT processes. This strategy might be useful to improve the clinical outcome after chronic renal disease.

Involvement of E2F1 transcriptional activity in cadmium-induced cell-cycle arrest at G1 in human lung fibroblasts

Human cadmium (Cd) exposure is associated with cancers of the lung and kidney. Using cDNA microarray analysis, we have recently reported that the expression of E2F1 is reduced by Cd in human lung fibroblasts, indicating the possibility of G1-phase arrest. To test this hypothesis, we investigated the effects of Cd on the cyclin-dependent kinase (CDK2) and retinoblastoma protein (Rb) regulatory pathways in WI38 human lung fibroblasts. We demonstrate here that G1-phase accumulation was induced by Cd in WI38 (wild-type for p53 and Rb), but not in the SV40 large T antigen-transformed variant WI38-VA13 (p53- and Rb-defective). Cd-induced cell-cycle arrest was associated with a decrease in CDK2 protein and with increase in p21 expression and p53 phosphorylation. Cd treatment caused a distinct increase in the formation of p21-cyclin E-CDK2 complex, as revealed by immunoprecipitation. The level of Rb-E2F1 complexes was increased, and the translocation of E2F1 to the nucleus was decreased by Cd treatment. Consequently, the transcriptional activity of E2F1 and the expression of the E2F1 target genes were also decreased by Cd. These results clearly demonstrate that Cd-mediated G1 arrest in WI38 cells is associated with the suppression of Rb phosphorylation and with the inhibition of E2F1 transcriptional activity.

COL1A1 oligodeoxynucleotides decoy: biochemical and morphologic effects in an acute wound repair model

Type I collagen is an integral component of granulation tissue and scar, that is highly dependent on TGFβ1, a member of a pro-fibrotic family of cytokines, for its promotion and deposition. Blocking COL1A1 gene transcription obstructs type I collagen synthesis, hindering the progress of granulation tissue deposition and fibrosis. Local injections of a double stranded oligodeoxynucleotide (dsODN) decoy, containing the TGFβ1 regulatory element that is located in the distal promoter of the COL1A1 gene, were investigated in a rat polyvinyl alcohol (PVA) sponge granulation tissue implant model. The effects on the granulation tissue deposition by dsODN decoy therapy were evaluated by the synthesis of types I and III collagens as well as ED-A (cellular) fibronectin. Fluorescently labeled dsODN was used to identify the distribution of the decoy molecules in the sponge implant relative to the observed histological effects. Morphological alterations in cells and changes in the organization of connective tissue were documented and evaluated. Collagen levels were reduced by half in implants treated with 10 nM dsODN decoy compared to scrambled dsODN-treated implants. Histologically, dsODN decoy treated implants had an increased cellular density without a corresponding increase in deposited connective tissue. Polarized light birefringence pattern of Sirius red-stained sections showed less collagen fibers accumulating between fibroblasts. The highest concentration of fluorescently labeled dsODN was identified within the interior margin of sponge implants, correlating to increased cellular density and an altered birefringence patterns. In conclusion, 10 nM dsODN decoy therapy reduced collagen deposition and altered the organization of granulation tissue, supporting its potential as a localized anti-fibrotic therapy for limiting fibrotic conditions.

E2F1 transcription is induced by genotoxic stress through ATM/ATR activation

E2F1, a member of the E2F family of transcription factors, plays a critical role in controlling both cell cycle progression and apoptotic cell death in response to DNA damage and oncogene activation. Following genotoxic stresses, E2F1 protein is stabilized by phosphorylation and acetylation driven to its accumulation. The aim of the present work was to examine whether the increase in E2F1 protein levels observed after DNA damage is only a reflection of an increase in E2F1 protein stability or is also the consequence of enhanced transcription of the E2F1 gene. The data presented here demonstrates that UV light and other genotoxics induce the transcription of E2F1 gene in an ATM/ATR dependent manner, which results in increasing E2F1 mRNA and protein levels. After genotoxic stress, transcription of cyclin E, an E2F1 target gene, was significantly induced. This induction was the result of two well-differentiated effects, one of them dependent on de novo protein synthesis and the other on the protein stabilization. Our results strongly support a transcriptional effect of DNA damaging agents on E2F1 expression. The results presented herein uncover a new mechanism involving E2F1 in response to genotoxic stress.

Transcriptional regulation of NF-kappaB by ring type decoy oligodeoxynucleotide in an animal model of nephropathy

Inflammation of the tubulointerstitial compartment, leading to fibrosis, is a major factor in the progressive loss of renal function in a wide variety of kidney diseases. In order to develop a therapeutic approach for nephropathy, we examined the simultaneous inhibition of transcription factor nuclear factor-kappaB (NF-kappaB), which is responsible for a wide range of cellular processes, especially inflammation, in a mouse model of unilateral ureteral obstruction. In this study, we employed a ring-type NF-kappaB (R-NF-kappaB) decoy oligodeoxynucleotide (ODN), containing consensus promoter sequences of NF-kappaB. This R-NF-kappaB decoy ODN is more highly resistant to degradation by nucleases than is the current phosphothiolated double stranded NF-kappaB decoy ODN. The inhibitory effect of R-NF-kappaB decoy ODN on nephropathy was confirmed by molecular and histological examinations. In addition, treatment with R-NF-kappaB decoy ODN reduced the activities of inflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-1beta. Interestingly, the treatment with R-NF-kappaB decoy ODN also suppressed the gene expression of transforming growth factor-beta1 and fibronectin, resulting in the inhibition of fibrotic changes. These results suggest that the inhibition of NF-kappaB using R-NF-kappaB decoy ODN has potential therapeutic application in the prevention of renal fibrosis.

Increase in nuclease resistance and incorporation of NF-kappaB decoy oligodeoxynucleotides by modification of the 3'-terminus

BACKGROUND

For the development of molecular therapy based on oligodeoxynucleotides (ODN), ODN have to be stable against nucleases and be specific to the target transcription factor. To decrease non-specific binding and degradation from the 3'-terminus of ODN, we designed partially annealed ODN by binding the extremities of two single strands, resulting in a ribbon-shaped ODN, so called ribbon-type decoy ODN (R-ODN).

METHODS

We evaluated the efficiency in the process of enzymatic ligation of R-ODN, the binding activity to nuclear factor-kappaB (NF-kappaB), and the stability against Exonuclease III and nucleases present in serum. The functional activity of R-ODN to inhibit NF-kappaB in vitro was evaluated in human aortic smooth muscle cells (VSMC): TNF-alpha-induced proliferation rate and MMP-9 expression were assessed after R-ODN transfection.

RESULTS AND CONCLUSIONS

Although R-ODN have a phosphodiester backbone, their physical conformation was designed to provide nuclease resistance without interfering with their binding activity. As expected, R-ODN showed more resistance to exonucleases and stability in 100% serum than non-modified decoy ODN (N-ODN). Importantly, the R-ODN construction did not interfere with its binding activity to NF-kappaB, similar to N-ODN. Transfection of R-ODN significantly inhibited the expression of MMP-9 induced by TNF-alpha in VSMC as assessed by real-time polymerase chain reaction (PCR), and R-ODN also inhibited the proliferation of VSMC induced by TNF-alpha (10 ng/ml), similar to phosphorothioate decoy ODN. Overall, the development of ribbon NF-kappaB decoy ODN could provide a useful tool for basic and clinical research.

Manipulating and understanding antibiotic production in Streptomyces coelicolor A3(2) with decoy oligonucleotides

We have adapted and extended the decoy oligonucleotide technique for use in prokaryotes. To identify cis-acting regulatory elements within a promoter, we developed a DNase I/T7 exonuclease footprinting technique and applied it to actII-orf4 from Streptomyces coelicolor A3(2), which encodes the pathway-specific activator for production of the antibiotic actinorhodin. Our in vivo mapping data allowed us to create decoy oligonucleotides incorporating the identified regulatory elements and to test whether their introduction into S. coelicolor affected antibiotic production. We mapped the promoter region when in a transcriptionally inactive state before the onset of actinorhodin production with the aim of designing decoy oligonucleotides capable of interfering with potential repressor binding and so stimulate actinorhodin production. Mapping identified five candidates for decoy oligonucleotides, and these were tested in a plate-based assay to rapidly validate their activity. A transfection protocol was developed for liquid cultures that enabled efficient uptake of decoys, and quantitative real-time PCR demonstrated decoy persistence for >70 h. Measurement of the effects on growth, expression of actII-orf4, and antibiotic production demonstrated that one of the decoys, in concordance with the plate assay, was more efficacious than the others in increasing actinorhodin production. Two of the identified regulatory elements occurred upstream of gene SCO5812, deletion of which reduced actinorhodin production, confirming that experimental analysis of regulatory motifs can provide new insights into factors influencing antibiotic production in streptomycetes.

Antiproliferative mechanisms of a transcription factor decoy targeting signal transducer and activator of transcription (STAT) 3: the role of STAT1

We previously developed a transcription factor decoy targeting signal transducer and activator of transcription 3 (STAT3) and reported antitumor activity in both in vitro and in vivo models of squamous cell carcinoma of the head and neck (SCCHN). Based on the known existence of STAT1-STAT3 heterodimers, the high sequence homology between STAT1 and STAT3, as well as expression of both STAT1 and STAT3 in SCCHN, we examined whether the STAT3 decoy interferes with STAT1 signaling. SCCHN cell lines with different STAT1 expression levels (but similar STAT3 levels) were used. Both cell lines were sensitive to the growth-inhibitory effects of the STAT3 decoy compared with a mutant control decoy. Intact STAT1 signaling was demonstrated by interferon-gamma (IFN-gamma)-mediated induction of STAT1 phosphorylation (Tyr701) and interferon-regulatory factor-1 (IRF-1) expression. Treatment with the STAT3 decoy (but not a mutant control decoy) resulted in inhibition of IRF-1 protein expression in both cell lines, indicating specific inhibition of STAT1 signaling by the STAT3 decoy. Because STAT1 is a potential tumor suppressor, we also investigated whether STAT1 signaling mitigated the therapeutic efficacy of the STAT3 decoy. In both PCI-15B and UM-22B cells, STAT1 siRNA treatment resulted in decreased STAT1 expression, without altering the antitumor activity of the STAT3 decoy. Likewise, the antitumor effects of the STAT3 decoy were not altered by STAT1 activation upon IFN-gamma treatment. These results suggest that the therapeutic mechanisms of STAT3 blockade using a transcription factor decoy are independent of STAT1 activation.

Alpha-lipoic acid inhibits fractalkine expression and prevents neointimal hyperplasia after balloon injury in rat carotid artery

Vascular inflammation induced by the proinflammatory cytokine/NF-kappaB pathway is one of the key mechanisms in the development of neointimal hyperplasia. Accumulating evidence suggests that a recently identified chemokine, fractalkine, is involved in arterial inflammation and atherogenesis. However, no study has examined the expression of neointimal fractalkine and the effects of pharmacological agents on this process. The purposes of this study were to measure neointimal fractalkine expression in the rat carotid artery following balloon injury and to determine if alpha-lipoic acid (ALA) inhibits fractalkine expression and neointimal hyperplasia. Balloon injury of the rat carotid artery induced fractalkine expression in the medial as well as neointimal regions. ALA inhibited this expression and consequently prevented neoinitmal hyperplasia in a balloon-injured rat carotid artery. Additionally, ALA inhibited TNF-alpha-stimulated fractalkine expression in cultured vascular smooth muscle cells (VSMCs), a process which is mediated through the NF-kappaB pathway. In addition to fractalkine, ALA successfully inhibited TNF-alpha-stimulated expression of vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 in cultured VSMCs. These data suggest that the cytokine-fractalkine system is involved in the pathogenesis of restenosis. The present study supports the possibility that ALA, which inhibits the NF-kappaB/fractalkine pathway, may be used to prevent neointimal hyperplasia after angioplasty or stenting.

A single decoy oligodeoxynucleotides targeting multiple oncoproteins produces strong anticancer effects

Cancer in general is a multifactorial process. Targeting a single factor may not be optimal in therapy, because single agents are limited by incomplete efficacy and dose-limiting adverse effects. Combination pharmacotherapy or "drug cocktail" therapy has value against many diseases, including cancers. We report an innovative decoy oligodeoxynucleotide (dODN) technology that we term complex decoy oligodeoxynucleotide (cdODNs) in which multiple cis elements are engineered into single dODNs attacking multiple target transcription factors, mimicking the drug cocktail approach. We designed dODNs targeting NF-kappaB, E2F, and Stat3 separately and a cdODN targeting NF-kappaB, E2F, and Stat3 concomitantly. We evaluated effects of this cdODN on expression of cancer-related genes, viability of human cancer cell lines, and in vivo tumor growth in nude mice. The cdODN targeting all NF-kappaB, E2F, and Stat3 together demonstrated enhancement of efficacy of more than 2-fold and increases in potency of 2 orders of magnitude compared with each of the dODNs or the combination of all three dODNs. The cdODN also showed earlier onset and longer-lasting action. Most strikingly, the cdODN acquired the ability to attack multiple molecules critical to cancer progression via multiple mechanisms, leading to elimination of regression. Real-time reverse transcription-polymerase chain reaction revealed that the cdODNs knocked down expression of the genes regulated by the target transcription factors. The cdODN strategy offers resourceful combinations of varying cis elements for concomitantly targeting multiple molecules in cancer biological processes and opens the door to "one-drug, multiple-target" therapy for a broad range of human cancers.

The Myc oncoprotein as a therapeutic target for human cancer

Myc expression is deregulated in a wide range of human cancers and is often associated with aggressive, poorly differentiated tumors. The Myc protein is a transcription factor that regulates a variety of cellular processes including cell growth and proliferation, cell-cycle progression, transcription, differentiation, apoptosis, and cell motility. Potential strategies that either inhibit the growth promoting effect of Myc and/or activate its pro-apoptotic function are presently being explored. In this review, we give an overview of Myc activation in human tumors and discuss current strategies aimed at targeting Myc for cancer treatment. Such therapies could have potential in combination with mechanistically different cytotoxic drugs to combat and eradicate tumors cells.

Ring-Sp1 decoy oligonucleotide effectively suppresses extracellular matrix gene expression and fibrosis of rat kidney induced by unilateral ureteral obstruction

Tubulointerstitial fibrosis is the consequence of an injury characterized by the accumulation of excess collagen and other extracellular matrix components, resulting in the destruction of the normal kidney architecture and subsequent loss of function. A transcription factor Sp1, originally described as a ubiquitous transcription factor, is involved in the basal expression of extracellular matrix genes and may, therefore, be important in fibrotic processes. Here, we report on the design of a ring-Sp1 decoy oligonucleotide, containing the consensus Sp1 binding sequence in a single decoy molecule without an open end, to create a novel therapeutic strategy for fibrosis. The ring-Sp1 decoy oligonucleotide is highly resistant to degradation by nucleases or serum compared to the conventional phosphorothioated double-stranded Sp1 decoy oligonucleotide, and effectively suppressed the expression of transforming growth factor-beta1 and fibronectin, the binding of Sp1 to the promoter region of these genes, and proliferation in response to serum in normal rat kidney fibroblasts. Moreover, treatment with the ring-Sp1 decoy in vivo significantly attenuates extracellular matrix gene expression in the rat kidney in which a unilateral ureteral obstruction had been induced. These results suggest that the ring-Sp1 decoy oligonucleotide represents promising therapeutic alternative to the conventional treatment of fibrotic disorders.

Oncogenes as novel targets for cancer therapy (part III): transcription factors

This is the third paper in a four-part serial review on potential therapeutic targeting of oncogenes. The previous parts described the involvement of oncogenes in different aspects of cancer growth and development, and considered the new technologies responsible for the advancement of oncogene identification, target validation, and drug design. Because of such advances, new specific and more efficient therapeutic agents can be developed for cancer. This part of the review continues the exploration of various oncogenes that we have grouped within seven categories: growth factors, tyrosine kinases, intermediate signaling molecules, transcription factors, cell cycle regulators, DNA damage repair genes, and genes involved in apoptosis. Part one discussed growth factors and tyrosine kinases and part two discussed intermediate signaling molecules. This portion of the review covers transcription factors and the various strategies being used to inhibit their expression or decrease their activities.

Cilostazol inhibits vascular smooth muscle cell growth by downregulation of the transcription factor E2F

Neointimal formation, the leading cause of restenosis, is caused by proliferation of vascular smooth muscle cells (VSMCs). Patients with diabetes mellitus have higher restenosis rates after coronary angioplasty than nondiabetic patients. Cilostazol, a selective type 3 phosphodiesterase inhibitor, is currently used to treat patients with diabetic vascular complications. Cilostazol is a potent antiplatelet agent that inhibits VSMC proliferation. In the present study, we examine whether the antiproliferative effect of cilostazol on VSMCs is mediated by inhibition of an important cell cycle transcription factor, E2F. Cilostazol inhibited the proliferation of human VSMCs in response to high glucose in vitro and virtually abolished neointimal formation in rats subjected to carotid artery injury in vivo. Moreover, the compound suppressed high-glucose-induced E2F-DNA binding activity, and the expression of E2F1, E2F2, cyclin A, and PCNA proteins. These data suggest that the beneficial effects of cilostazol on high-glucose-stimulated proliferation of VSMCs are mediated by the downregulation of E2F activity and expression of its downstream target genes, including E2F1, E2F2, cyclin A, and PCNA.

Transcriptional induction of FosB/DeltaFosB gene by mechanical stress in osteoblasts

Mechanical stress to bone plays a critical role in maintaining bone mass and strength. However, the molecular mechanism of mechanical stress-induced bone formation is not fully understood. In the present study, we demonstrate that FosB and its spliced variant DeltaFosB, which is known to increase bone mass by stimulating bone formation in vivo, is rapidly induced by mechanical loading in mouse hind limb bone in vivo and by fluid shear stress (FSS) in mouse calvarial osteoblasts in vitro both at the mRNA and protein levels. FSS induction of FosB/DeltaFosB gene expression was dependent on gadlinium-sensitive Ca(2+) influx and subsequent activation of ERK1/2. Analysis of the mouse FosB/DeltaFosB gene upstream regulatory region with luciferase reporter gene assays revealed that the FosB/DeltaFosB induction by FSS occurred at the transcriptional level and was conferred by a short fragment from -603 to -327. DNA precipitation assays and DNA decoy experiments indicated that ERK-dependent activation of CREB binding to a CRE/AP-1 like element (designated "CRE2") at the position of -413 largely contributed to the transcriptional effects of FSS. These results suggest that DeltaFosB participates in mechanical stress-induced intracellular signaling cascades that activate the osteogenic program in osteoblasts.

Construction, stability, and activity of multivalent circular anticoagulant aptamers

Here we describe the design and construction of multivalent circular DNA aptamers. Four aptameric binding motifs directed at blood-borne targets are used as a model set from which larger, multidomain aptamers are constructed in a straightforward manner. Intra- or intermolecular ligation of precursor oligonucleotides provides a stabilizing mechanism against degradation by the predominant exonuclease activity of blood products without the need for post-selection chemical modification. In many cases, circular DNA aptamer half-lives are extended beyond 10 h in serum and plasma, making such constructs viable for therapeutic and diagnostic applications. Duplexes and three-way junctions are used as scaffold architectures around which two, three, or four aptameric motifs can be arranged in a structurally defined manner, giving rise to improved binding characteristics through stability and avidity gains. Circular aptamers targeted against thrombin display improved anticoagulant potency with EC50 values 2-3-fold better than those of the canonical GS-522 thrombin DNA aptamer. Intrinsic duplex regions provide an opportunity to incorporate additional transcription factor binding motifs, whereas ancillary loops can be used to provide further functionality. These anticoagulant aptamers provide a starting point for merging the principles of DNA nanotechnology with aptameric functions.

Sp1-decoy oligodeoxynucleotide inhibits high glucose-induced mesangial cell proliferation

Mesangial expansion caused by cell proliferation and glomerular extracellular matrix accumulation is one of the earliest renal abnormalities observed at the onset of hyperglycemia in diabetes mellitus. Transcription factor Sp1 is implicated in the transcriptional regulation of a wide range of genes participating in cell proliferation, and is assumed to play an essential role in mesangial expansion. We have generated a phosphorothioated double-stranded Sp1-decoy oligodeoxynucleotide that effectively blocks Sp1 binding to the promoter region for transcriptional regulation of transforming growth factor-beta1 and plasminogen activator inhibitor-1. The Sp1-decoy oligodeoxynucleotide suppressed transcription of these cytokines and proliferation of primary rat mesangial cells in response to high glucose. These results suggest that the Sp1-decoy oligodeoxynucleotide could be a powerful tool in preventing the pathogenesis of renal hypertrophy.