Inhibitory effects of novel E2F decoy oligodeoxynucleotides on mesangial cell proliferation by coexpression of E2F/DP

NF-κB Decoy ODN-Loaded Poly(Lactic-co-glycolic Acid) Nanospheres Inhibit Alveolar Ridge Resorption

Residual ridge resorption combined with dimensional loss resulting from tooth extraction has a prolonged correlation with early excessive inflammation. Nuclear factor-kappa B (NF-κB) decoy oligodeoxynucleotides (ODNs) are double-stranded DNA sequences capable of downregulating the expression of downstream genes of the NF-κB pathway, which is recognized for regulating prototypical proinflammatory signals, physiological bone metabolism, pathologic bone destruction, and bone regeneration. The aim of this study was to investigate the therapeutic effect of NF-κB decoy ODNs on the extraction sockets of Wistar/ST rats when delivered by poly(lactic-co-glycolic acid) (PLGA) nanospheres. Microcomputed tomography and trabecular bone analysis following treatment with NF-κB decoy ODN-loaded PLGA nanospheres (PLGA-NfDs) demonstrated inhibition of vertical alveolar bone loss with increased bone volume, smoother trabecular bone surface, thicker trabecular bone, larger trabecular number and separation, and fewer bone porosities. Histomorphometric and reverse transcription-quantitative polymerase chain reaction analysis revealed reduced tartrate-resistant acid phosphatase-expressing osteoclasts, interleukin-1β, tumor necrosis factor-α, receptor activator of NF-κB ligand, turnover rate, and increased transforming growth factor-β1 immunopositive reactions and relative gene expression. These data demonstrate that local NF-κB decoy ODN transfection via PLGA-NfD can be used to effectively suppress inflammation in a tooth-extraction socket during the healing process, with the potential to accelerate new bone formation.

Cold Shock Proteins Mediate GN with Mesangioproliferation

DNA binding protein A (DbpA) is a member of the human cold shock domain-containing protein superfamily, with known functions in cell proliferation, differentiation, and stress responses. DbpA mediates tight junction-associated activities in tubular epithelial cells, but the function of DbpA in mesangial cells is unknown. Here, we found DbpA protein expression restricted to vascular smooth muscle cells in healthy human kidney tissue but profound induction of DbpA protein expression within the glomerular mesangial compartment in mesangioproliferative nephritis. In vitro, depletion or overexpression of DbpA using lentiviral constructs led to inhibition or promotion, respectively, of mesangial cell proliferation. Because platelet-derived growth factor B (PDGF-B) signaling has a pivotal role in mesangial cell proliferation, we examined the regulatory effect of PDGF-B on DbpA. In vitro studies of human and rat mesangial cells confirmed a stimulatory effect of PDGF-B on DbpA transcript numbers and protein levels. Additional in vivo investigations showed DbpA upregulation in experimental rat anti-Thy1.1 nephritis and murine mesangioproliferative nephritis models. To interfere with PDGF-B signaling, we injected nephritic rats with PDGF-B neutralizing aptamers or the MEK/ERK inhibitor U0126. Both interventions markedly decreased DbpA protein expression. Conversely, continuous PDGF-B infusion in healthy rats induced DbpA expression predominantly within the mesangial compartment. Taken together, these results indicate that DbpA is a novel target of PDGF-B signaling and a key mediator of mesangial cell proliferation.

E2F1 and E2F2 induction in response to DNA damage preserves genomic stability in neuronal cells

E2F transcription factors regulate a wide range of biological processes, including the cellular response to DNA damage. In the present study, we examined whether E2F family members are transcriptionally induced following treatment with several genotoxic agents, and have a role on the cell DNA damage response. We show a novel mechanism, conserved among diverse species, in which E2F1 and E2F2, the latter specifically in neuronal cells, are transcriptionally induced after DNA damage. This upregulation leads to increased E2F1 and E2F2 protein levels as a consequence of de novo protein synthesis. Ectopic expression of these E2Fs in neuronal cells reduces the level of DNA damage following genotoxic treatment, while ablation of E2F1 and E2F2 leads to the accumulation of DNA lesions and increased apoptotic response. Cell viability and DNA repair capability in response to DNA damage induction are also reduced by the E2F1 and E2F2 deficiencies. Finally, E2F1 and E2F2 accumulate at sites of oxidative and UV-induced DNA damage, and interact with γH2AX DNA repair factor. As previously reported for E2F1, E2F2 promotes Rad51 foci formation, interacts with GCN5 acetyltransferase and induces histone acetylation following genotoxic insult. The results presented here unveil a new mechanism involving E2F1 and E2F2 in the maintenance of genomic stability in response to DNA damage in neuronal cells.

Small-nucleic-acid-based therapeutic strategy targeting the transcription factors regulating the vascular inflammation, remodeling and fibrosis in atherosclerosis

Atherosclerosis arises when injury to the arterial wall induces an inflammatory cascade that is sustained by a complex network of cytokines, together with accumulation of lipids and fibrous material. Inflammatory cascades involve leukocyte adherence and chemotaxis, which are coordinated by the local secretion of adhesion molecules, chemotactic factors, and cytokines. Transcription factors are critical to the integration of the various steps of the cascade response to mediators of vascular injury, and are induced in a stimulus-dependent and cell-type-specific manner. Several small-nucleic-acid-based therapeutic strategies have recently been developed to target transcription factors: antisense oligodeoxynucleotides, RNA interference, microRNA, and decoy oligodeoxynucleotides. The aim of this review was to provide an overview of these particular targeted therapeutic strategies, toward regulation of the vascular inflammation, remodeling and fibrosis associated with atherosclerosis.

A novel long noncoding RNA AK001796 acts as an oncogene and is involved in cell growth inhibition by resveratrol in lung cancer

Lung cancer is the most common form of cancer throughout the world. The specific targeting of long noncoding RNAs (lncRNAs) by resveratrol opened a new avenue for cancer chemoprevention. In this study, we found that 21 lncRNAs were upregulated and 19 lncRNAs were downregulated in lung cancer A549 cells with 25 μmol/L resveratrol treatment determined by microarray analysis. AK001796, the lncRNA with the most clearly altered expression, was overexpressed in lung cancer tissues and cell lines, but its expression was downregulated in resveratrol-treated lung cancer cells. By monitoring cell proliferation and growth in vitro and tumor growth in vivo, we observed a significant reduction in cell viability in lung cancer cells and a slow growth in the tumorigenesis following AK001796 knockdown. We also found that AK001796 knockdown caused a cell-cycle arrest, with significant increases in the percentage of cells in G0/G1 in lung cancer cells. By using cell cycle pathway-specific PCR arrays, we detected changes in a number of cell cycle-related genes related to lncRNA AK001796 knockdown. We further investigated whether AK001796 participated in the anticancer effect of resveratrol and the results showed that reduced lncRNA AK001796 level potentially impaired the inhibitory effect of resveratrol on cell proliferation. To our knowledge, this is the first study to report the changes in an lncRNA expression profile induced by resveratrol in lung cancer.

Retinoic acid-related orphan receptor alpha reprograms glucose metabolism in glutamine-deficient hepatoma cells

The metabolism of glutamine and glucose is recognized as a promising therapeutic target for the treatment of cancer; however, targeted molecules that mediate glutamine and glucose metabolism in cancer cells have not been addressed. Here, we show that restricting the supply of glutamine in hepatoma cells, including HepG2 and Hep3B cells, markedly increased the expression of retinoic acid-related orphan receptor alpha (RORα). Up-regulation of RORα in glutamine-deficient hepatoma cells resulted from an increase in the level of cellular reactive oxygen species and in the nicotinamide adenine dinucleotide phosphate/nicotinamide adenine dinucleotide phosphate reduced (NADP+ /NADPH) ratio, which was consistent with a reduction in the glutathione/glutathione disulfide (GSH/GSSG) ratio. Adenovirus (Ad)-mediated overexpression of RORα (Ad-RORα) or treatment with the RORα activator, SR1078, reduced aerobic glycolysis and down-regulated biosynthetic pathways in hepatoma cells. Ad-RORα and SR1078 reduced the expression of pyruvate dehydrogenase kinase 2 (PDK2) and inhibited the phosphorylation of pyruvate dehydrogenase and subsequently shifted pyruvate to complete oxidation. The RORα-mediated decrease in PDK2 levels was caused by up-regulation of p21, rather than p53. Furthermore, RORα inhibited hepatoma growth both in vitro and in a xenograft model in vivo. We also found that suppression of PDK2 inhibited hepatoma growth in a xenograft model. These findings mimic the altered glucose utilization and hepatoma growth caused by glutamine deprivation. Finally, tumor tissue from 187 hepatocellular carcinoma patients expressed lower levels of RORα than adjacent nontumor tissue, supporting a potential beneficial effect of RORα activation in the treatment of liver cancer.

CONCLUSION

RORα mediates reprogramming of glucose metabolism in hepatoma cells in response to glutamine deficiency. The relationships established here between glutamine metabolism, RORα expression and signaling, and aerobic glycolysis have implications for therapeutic targeting of liver cancer metabolism.

p19INK4d is involved in the cellular senescence mechanism contributing to heterochromatin formation

BACKGROUND

During evolution, organisms with renewable tissues have developed mechanisms to prevent tumorigenesis, including cellular senescence and apoptosis. Cellular senescence is characterized by a permanent cell cycle arrest triggered by both endogenous stress and exogenous stress. The p19INK4d, a member of the family of cyclin-dependent kinase inhibitors (INK4), plays an important role on cell cycle regulation and in the cellular DNA damage response. We hypothesize that p19INK4d is a potential factor involved in the onset and/or maintenance of the senescent state.

METHODS

Senescence was confirmed by measuring the cell cycle arrest and the senescence-associated β-galactosidase activity. Changes in p19INK4d expression and localization during senescence were determined by Western blot and immunofluorescence assays. Chromatin condensation was measured by microccocal nuclease digestion and histone salt extraction.

RESULTS

The data presented here show for the first time that p19INK4d expression is up-regulated by different types of senescence. Changes in senescence-associated hallmarks were driven by modulation of p19 expression indicating a direct link between p19INK4d induction and the establishment of cellular senescence. Following a senescence stimulus, p19INK4d translocates to the nucleus and tightly associates with chromatin. Moreover, reduced levels of p19INK4d impair senescence-related global genomic heterochromatinization. Analysis of p19INK4d mRNA and protein levels in tissues from differently aged mice revealed an up-regulation of p19INK4d that correlates with age.

CONCLUSION

We propose that p19INK4d participates in the cellular mechanisms that trigger senescence by contributing to chromatin compaction.

GENERAL SIGNIFICANCE

This study provides novel insights into the dynamics process of cellular senescence, a central tumor suppressive mechanism.

E2F1-mediated upregulation of p19INK4d determines its periodic expression during cell cycle and regulates cellular proliferation

Background

A central aspect of development and disease is the control of cell proliferation through regulation of the mitotic cycle. Cell cycle progression and directionality requires an appropriate balance of positive and negative regulators whose expression must fluctuate in a coordinated manner. p19INK4d, a member of the INK4 family of CDK inhibitors, has a unique feature that distinguishes it from the remaining INK4 and makes it a likely candidate for contributing to the directionality of the cell cycle. p19INK4d mRNA and protein levels accumulate periodically during the cell cycle under normal conditions, a feature reminiscent of cyclins.

Methodology/Principal Findings

In this paper, we demonstrate that p19INK4d is transcriptionally regulated by E2F1 through two response elements present in the p19INK4d promoter. Ablation of this regulation reduced p19 levels and restricted its expression during the cell cycle, reflecting the contribution of a transcriptional effect of E2F1 on p19 periodicity. The induction of p19INK4d is delayed during the cell cycle compared to that of cyclin E, temporally separating the induction of these proliferative and antiproliferative target genes. Specific inhibition of the E2F1-p19INK4d pathway using triplex-forming oligonucleotides that block E2F1 binding on p19 promoter, stimulated cell proliferation and increased the fraction of cells in S phase.

Conclusions/Significance

The results described here support a model of normal cell cycle progression in which, following phosphorylation of pRb, free E2F induces cyclin E, among other target genes. Once cyclinE/CDK2 takes over as the cell cycle driving kinase activity, the induction of p19 mediated by E2F1 leads to inhibition of the CDK4,6-containing complexes, bringing the G1 phase to an end. This regulatory mechanism constitutes a new negative feedback loop that terminates the G1 phase proliferative signal, contributing to the proper coordination of the cell cycle and provides an additional mechanism to limit E2F activity.

Decoy oligodeoxynucleotide targeting activator protein-1 (AP-1) attenuates intestinal inflammation in murine experimental colitis

Various therapies are used for inflammatory bowel diseases (IBD), though none seem to be extremely effective. AP-1 is a major transcription factor that upregulates genes involved in immune and proinflammatory responses. We investigated decoy oligodeoxynucleotide (ODN) targeting AP-1 to prevent dextran sulfate sodium (DSS)-induced colitis in mice. Functional efficacies of synthetic decoy and scrambled ODNs were evaluated in vitro by a reporter gene luciferase assay and measuring flagellin-induced IL-8 expression by HCT-15 cells transfected with ODNs. Experimental colitis was induced in mice with a 2.5% DSS solution in drinking water for 7 days, and decoy or scrambled ODNs were intraperitoneally injected from days 2 to 5. Colitis was assessed by weight loss, colon length, histopathology, and detection of myeloperoxidase (MPO), IL-1beta, and TNF-alpha in colon tissue. Therapeutic effects of AP-1 and NF-kappaB decoy ODNs were compared. Transfection of AP-1 decoy ODN inhibited AP-1 transcriptional activity in reporter assays and flagellin-induced IL-8 production in vitro. In mice, AP-1 decoy ODN, but not scrambled ODN, significantly inhibited weight loss, colon shortening, and histological inflammation induced by DSS. Further, AP-1 decoy ODN decreased MPO, IL-1beta, and TNF-alpha in colonic tissue of mice with DSS-induced colitis. The AP-1 decoy therapeutic effect was comparable to that of NF-kappaB decoy ODN, which also significantly decreased intestinal inflammation. Double-strand decoy ODN targeting AP-1 effectively attenuated intestinal inflammation associated with experimental colitis in mice, indicating the potential of targeting proinflammatory transcription factors in new therapies for IBD.

Suppression of mesangial cell proliferation and extracellular matrix production in streptozotocin-induced diabetic rats by Sp1 decoy oligodeoxynucleotide in vitro and in vivo

Transcription factor Sp-1 is an important fibrogenic factor that is involved in the pathogenesis of diabetic nephropathy. In this study, we examined the effect of Sp1 decoy oligodeoxynucleotides (ODNs) on the extracellular matrix (ECM) gene expression in cultured rat mesangial cells (RMC) and streptozotocin (STZ)-induced diabetic rats. The ring-type Sp1 decoy ODNs significantly decreased ECM mRNA expression and Sp1 binding to the promoter region of these PDGF-induced genes in RMC. In addition, the decoy ODNs was introduced into the left renal artery of diabetic rat using the hemagglutinating virus of Japan (HVJ)-liposome mediated gene transfer method and effectively delivered to the kidney. On 14 days after ring-type Sp1 decoy ODNs injection, type IV collagen, fibronectin mRNA, and protein expression were markedly decreased, and the rate of urinary creatinine excretion was reduced in the ring-type Sp1 decoy ODNs-treated diabetic rats. These results indicated that the ring-type Sp1 decoy ODNs would be superior to P-Sp1 ODNs. Also, the R-Sp1 decoy ODN when introduced in vivo, effectively reduced ECM production during the progression of nephropathy. Therefore, ring-type Sp1 decoy is a promising tool for developing new therapeutic applications for progressive diabetic nephropathy.

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.

Inhibitory effect of ribbon-type NF-kappaB decoy oligodeoxynucleotides on osteoclast induction and activity in vitro and in vivo

In this study we examined the effect of ribbon-type (circular-type) NF-κB decoy oligodeoxynucleotides (RNODN) on osteoclast induction and activity. We extracted bone marrow cells from the femurs of rats and incubated non-adherent cells with receptor activator of nuclear factor κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). First, transfer efficiency into osteoclasts and their precursors, resistance to exonuclease, and binding activity of decoy to NF-κB were examined. Next, to examine the effect of RNODN on osteoclast induction and activity, osteoclast differentiation and pit formation assays were performed. RNODN were injected into the ankle joints of rats with collagen-induced arthritis. Joint destruction and osteoclast activity were examined by histological study. The resistance of RNODN to exonuclease and their binding activity on NF-κB were both greater than those of phosphorothionated NF-κB decoy oligodeoxynucleotides. The absolute number of multinucleate cells scoring positive for tartrate-resistant acid phosphatase was significantly decreased in the RNODN-treated group. The average calcified matrix resorbed area was significantly decreased in the RNODN-treated group. Histological study showed marked suppression of joint destruction and osteoclast activity by intra-articular injection of RNODN. These results suggest the inhibitory effect of RNODN on the induction and activity of osteoclasts. Direct intra-articular injection of RNODN into the joints may be an effective strategy for the treatment of arthritis.

TGF-beta1 siRNA suppresses the tubulointerstitial fibrosis in the kidney of ureteral obstruction

TGF-beta1 has been known as an important factor in tubulointerstitial fibrosis which is a common process in most progressive renal diseases. We hypothesized that the interstitial fibrosis could be prevented by abolishing TGF-beta1 function in unilateral ureteral obstruction (UUO)-induced renal fibrosis. shRNA vectors were generated to suppress TGF-beta1 expression at a high glucose concentration which allowed the maximal induction of TGF-beta1 in primary rat mesangial cells. An shRNA vector, designated shTB1d, significantly suppressed TGF-beta1 in both transcriptional and translational levels in vitro cultured cells and in vivo fibrosis-induced mouse kidney, accompanied by the suppression of target genes (e.g., type I collagen and PAI-1) of TGF-beta1. Furthermore, the shTB1d suppressed the expression of TGF-beta1 and type I collagen in tubulointerstitial cells until day 7 after UUO-induced fibrosis, but none- or vector-treated mice maintained their expression, suggesting that the TGF-beta1 shRNA delays the process of renal fibrosis in UUO mouse model. This work would provide a valuable tool to prevent tubulointerstitial fibrosis using RNA interference strategy.

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.

E2F decoy oligodeoxynucleotides effectively inhibit growth of human tumor cells

Abnormal cell proliferation, largely dependent upon deregulation of cell-cycle regulatory proteins, is an important feature of several forms of human cancer. The transcription factor, E2F, plays a critical role in the trans-activation of several genes involved in cell-cycle regulation, thereby regulating cell growth. We have demonstrated that E2F decoy oligodeoxynucleotides (ODNs) with a circular dumbbell structure (CD-E2F decoy) corresponding to E2F binding sites effectively inhibit cell proliferation of primary cultured cells. Here we found that the E2F decoy ODNs inhibited serum-induced promoter activity of E2F-dependent genes in a sequence-specific manner in a RB-positive human osteosarcoma, U2OS, as well as in a RB-negative human cervical carcinoma, C33A. This E2F decoy ODN strongly inhibited gene expression of endogenous E2F1 and PCNA and proliferation of these cancer cells. Our results suggest that this decoy ODN strategy could represent a powerful investigative and potentially therapeutic strategy in the prevention and treatment of cancer.