Hammerhead ribozyme targeting connective tissue growth factor mRNA blocks transforming growth factor-beta mediated cell proliferation

Modulation of Fibroblasts in Conjunctival Wound Healing

Modulating conjunctival wound healing has the potential to improve outcomes after glaucoma filtration surgery and for several ocular disorders, including ocular cicatrial pemphigoid, vernal keratoconjunctivitis, and pterygium. Although anti-inflammatories and antimetabolites have been used with success, these nonspecific agents are not without their complications. The search for novel and more targeted means to control conjunctival fibrosis without such limitations has brought much attention to the regulation of fibroblast proliferation, differentiation, extracellular matrix production, and apoptosis. This review provides an update on where we stand with current antifibrotic agents and outlines the strategies that novel agents use, as they evolve from the bench to the bedside.

Connective tissue growth factor is not necessary for haze formation in excimer laser wounded mouse corneas

We sought to determine if connective tissue growth factor (CTGF) is necessary for the formation of corneal haze after corneal injury. Mice with post-natal, tamoxifen-induced, knockout of CTGF were subjected to excimer laser phototherapeutic keratectomy (PTK) and the corneas were allowed to heal. The extent of scaring was observed in non-induced mice, heterozygotes, and full homozygous knockout mice and quantified by macrophotography. The eyes from these mice were collected after euthanization for re-genotyping to control for possible Cre-mosaicism. Primary corneal fibroblasts from CTGF knockout corneas were established in a gel plug assay. The plug was removed, simulating an injury, and the rate of hole closure and the capacity for these cells to form light reflecting cells in response to CTGF and platelet-derived growth factor B (PDGF-B) were tested and compared to wild-type cells. We found that independent of genotype, each group of mice was still capable of forming light reflecting haze in the cornea after laser ablation (p = 0.40). Results from the gel plug closure rate in primary cell cultures of knockout cells were not statistically different from serum starved wild-type cells, independent of treatment. Compared to the serum starved wild-type cells, stimulation with PDGF-BB significantly increased the KO cell culture’s light reflection (p = 0.03). Most interestingly, both reflective cultures were positive for α-SMA, but the cellular morphology and levels of α-SMA were distinct and not in proportion to the light reflection seen. This new work demonstrates that corneas without CTGF can still form sub-epithelial haze, and that the light reflecting phenotype can be reproduced in culture. These data support the possibilities of growth factor redundancy and that multiple pro-haze pathways exist.

Conditional knockout of CTGF affects corneal wound healing

PURPOSE

This study aimed to elucidate the role of connective tissue growth factor (CTGF) in healthy eyes and wounded corneas of mice and rabbits. Conditional knockout mice were used to determine the role of CTGF in corneal healing.

METHODS

CTGF expression was determined using transgenic mice carrying CTGF promoter driven-eGFP, quantitative RT-PCR, and immunofluorescent staining. Mice that carried two floxed CTGF alleles and a Cre/ERT2 transgene under the control of human ubiquitin C (ubc) promoter were used to conditionally delete CTGF gene in a tamoxifen-inducible manner. Phototherapeutic keratectomy (PTK) was used to generate an acute corneal wound and corneal re-epithelialization was assessed by fluorescein staining.

RESULTS

Connective tissue growth factor expression was found in multiple ocular tissues with relatively high levels in the corneal endothelium, lens subcapsular epithelium, and in the vasculature of the iris and retina. Wounded corneas responded with an immediate upregulation of CTGF in the epithelium at the wound margin and a sustained CTGF induction during re-epithelialization. At the onset of haze formation, CTGF protein becomes more focused in the basal epithelium. Deletion of the CTGF gene caused a 40% reduction (P < 0.01) in the cornea re-epithelialization rate in knockout mice compared with wild-type mice.

CONCLUSIONS

Connective tissue growth factor is expressed in the naïve cornea, lens, iris, and retina, and is expressed immediately after epithelial injury. Loss of CTGF impairs efficient re-epithelialization of corneal wounds.

Triple combination of siRNAs targeting TGFβ1, TGFβR2, and CTGF enhances reduction of collagen I and smooth muscle actin in corneal fibroblasts

PURPOSE

Transforming growth factor β1 (TGFβ1), TGFβ receptor (TGFβR2), and connective tissue growth factor (CTGF) are key regulators of fibrosis in the cornea and in other tissues, including liver, skin, and kidney. We developed an antifibrotic treatment targeting these three critical scarring genes by using a combination of small interfering RNAs (siRNAs) and assessed its effect on downstream scarring genes, collagen I, and α smooth muscle actin (SMA).

METHODS

Up to six individual siRNAs for each of the three target gene mRNAs were transfected into cultures of rabbit corneal fibroblasts at concentrations from 15 to 90 nM. The knockdown of target gene proteins was measured by ELISA, and the two most effective siRNAs were tested in dual combinations. Knockdown percentages of both individual and dual siRNA combinations were analyzed for synergy by using combination index to predict "effective" and "ineffective" triple siRNA combinations. Effects of both triple siRNA combinations on target and downstream mRNAs were measured by using quantitative RT-PCR, and levels of SMA protein were assessed by immunohistochemistry.

RESULTS

Single and dual siRNA combinations produced a wide range of protein knockdown of target genes (5%-80%). The effective triple siRNA combination significantly reduced mRNA levels of target genes (>80%) and downstream scarring genes (>85%), and of SMA protein (>95%), and significantly reduced cell migration without reducing cell viability.

CONCLUSIONS

Simultaneous targeting of TGFβ1, TGFβR2, and CTGF genes by effective triple siRNA combination produced high knockdown of target and downstream scarring genes without cell toxicity, which may have clinical applications in reducing corneal fibrosis and scarring in other tissues.

Functional characteristics of connective tissue growth factor on human tenon's capsule fibroblast

PURPOSE OF THE STUDY

To explore the characteristic of connective tissue growth factor (CTGF) on the phenotype transition, extracellular matrix (ECM) synthesis and proliferation of human Tenon's capsule fibroblasts (HTFs).

MATERIALS AND METHODS

HTFs were obtained from patients during cataract surgery and induced by CTGF (1 to 100 µg/L). Western blot and immunofluorescence were performed to observe the expression of alpha smooth muscle actin (α-SM-actin) protein. The levels of mRNAs were quantified by real-time PCR. Col I and FN expression at both protein and RNA levels were tested after induction by CTGF and transforming growth factor β (TGF-β), respectively. Statistical significance was assumed if p < 0.05.

RESULTS

CTGF upregulated the expression of α-SM-actin in cultured HTFs. Its maximum effect at protein level attained under the optimal concentration of 50 μg/L at the peak time of 48 hours, though still weaker than the effect of TGF-β1 (10 μg/L, p < 0.05). The expression of Col I and FN at both protein and mRNA levels was elevated by the induction of CTGF (50 μg/L) (p < 0.01) and TGF-β1 (10 μg/L) (p < 0.05), while CTGF (50 μg/L) showed a greater effect than the latter (p < 0.05). CTGF (1 to100 μg/L) increased the proliferation of HTFs significantly (p < 0.05).

CONCLUSIONS

CTGF induced the phenotype transition of HTFs individually and significantly promoted their proliferation. Moreover, it promoted ECM synthesis, thus demonstrating its role as a crucial factor in fibrosis. Thus, CTGF could potentially be a safer and more efficient target than TGF-β at suppressing scar formation after filtering surgery.

Ribozyme-mediated gene knock down strategy to dissect the consequences of PDGF stimulation in vascular smooth muscle cells

Background

Vascular Smooth Muscle Cells (VSMCs), due to their plasticity and ability to shift from a physiological contractile-quiescent phenotype to a pathological proliferating-activated status, play a central role in the onset and progression of atherosclerosis and cardiovascular diseases. PDGF-BB, among a series of cytokines and growth factors, has been identified as the critical factor in this phenotypic switch. In order to obtain new insights on the molecular effects triggered by PDGF-BB, a hammerhead ribozyme targeting the membrane receptor PDGFR-β was applied to inhibit PDGF pathway in porcine VSMCs.

Findings

Ribozymes, loaded on a cationic polymer-based vehicle, were delivered into cultured VSMCs. A significant impairment of the activation mechanisms triggered by PDGF-BB was demonstrated since cell migration decreased after treatments. In order to functionally validate the effects of PDGFR-β partial knock down we focused on the phosphorylation status of two proteins, protein disulfide isomerase-A3 (PDI-A3) and heat shock protein-60 (HSP-60), previously identified as indicative of VSMC phenotypic switch after PDGF-BB stimulation. Interestingly, while PDI-A3 phosphorylation was counteracted by the ribozyme administration indicating that PDI-A3 is a factor downstream the receptor signalling cascade, the HSP-60 phosphorylation status was greatly increased by the ribozyme administration.

Conclusion

These contradictory observations suggested that PDGF-BB might trigger different parallel pathways that could be modulated by alternative isoforms of the receptors for the growth factor. In conclusion the knock down strategy here described enables to discriminate between two tightly intermingled pathways. Moreover it opens new attractive perspectives in functional investigations where combined gene knock down and proteomic technologies would allow the identification of key factors and pathways involved in VSMC-linked pathological disorders.

Activation of JNK signaling mediates connective tissue growth factor expression and scar formation in corneal wound healing

Connective Tissue Growth Factor (CTGF) and Transforming growth factor-β1 (TGF-β1) are key growth factors in regulating corneal scarring. Although CTGF was induced by TGF-β1 and mediated many of fibroproliferative effects of TGF-β1, the signaling pathway for CTGF production in corneal scarring remains to be clarified. In the present study, we firstly investigated the effects of c-Jun N-terminal kinase (JNK) on CTGF expression induce by TGF-β1 in Telomerase-immortalized human cornea stroma fibroblasts (THSF). Then, we created penetrating corneal wound model and determined the effect of JNK in the pathogenesis of corneal scarring. TGF-β1 activated MAPK pathways in THSF cells. JNK inhibitor significantly inhibited CTGF, fibronectin and collagen I expression induced by TGF-β1 in THSF. In corneal wound healing, the JNK inhibitor significantly inhibited CTGF expression, markedly improved the architecture of corneal stroma and reduced corneal scar formation, but did not have a measurable impact on corneal wound healing in vivo. Our results indicate that JNK mediates the expression of CTGF and corneal scarring in corneal wound healing, and might be considered as specific targets of drug therapy for corneal scarring.

Inhibition effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits

PURPOSE

To observe the inhibitory effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits.

MATERIALS AND METHODS

Twenty-seven healthy New Zealand rabbits were selected and underwent Epi-LASIK surgery. According to a self comparison principle, these rabbits were randomly divided into three groups. The first group was treated with tetrandrine eye drops (Tet), the second (negative control, NC) group was treated with pure solvent, and the third group was treated with fluorometholone (FML) solvent. Haze grades of each group were respectively observed by slit lamp exam at half-month, one month, and two months after surgery. After corneal tissues were extracted, optical microscopy, Sirius Red staining, immunohistochemistry, and semi-quantitative RT-PCR tests were conducted, in order to test collagen formation of operated eyes after surgery and expression of transformation growth factor beta 2 (TGF-β(2)) in corneal stroma.

RESULTS

At a half month and one month after surgery, haze grades and type III collagen expression in Tet and FML groups were significantly lower than that in NC groups (P < 0.01). No statistical difference was observed between Tet and FML groups. Immunohistochemistry showed that, at each time point after surgery, expressions of TGF-β(2) protein in Tet and FML groups were significantly lower than that in the NC group (P < 0.01), whereas there was no statistical difference between Tet and FML groups. The expression level of TGF-β(2) protein increased, reaching its peak one month after surgery. RT-PCR also showed that, at each point after surgery, the TGF-β(2) mRNA expression in Tet and FML groups was lower than that in the NC group (P < 0.01), nevertheless no statistical difference was observed between Tet and FML groups.

CONCLUSIONS

Like FML, Tet could inhibit haze formation in rabbits after Epi-LASIK surgery, possible through TGF-β(2)-collagen-III pathway.

Gene therapy for diseases of the cornea - a review

The cornea is particularly suited to gene therapy. The cornea is readily accessible, normally transparent, and is somewhat sequestrated from the general circulation and the systemic immune system. The principle of genetic therapy for the cornea is to use an appropriate vector system to transfer a gene to the cornea itself, or to the ocular environs, or systemically, so that a transgenic protein will be expressed that will modulate congenital or acquired disease. The protein may be structural such as a collagen, or functionally active such as an enzyme, cytokine or growth factor that may modulate a pathological process. Alternatively, gene expression may be silenced by the use of modalities such as antisense oligonucleotides. Interestingly, despite a very considerable amount of work in animal models, clinical translation directed to gene therapy of the human cornea has been minimal. This is in contrast to gene therapy for monogenic inherited diseases of the retina, where promising early results of clinical trials for Leber's congenital amaurosis have already been published and a number of other trials are ongoing.

The role of c-Jun N-terminal kinases 1/2 in transforming growth factor beta(1)-induced expression of connective tissue growth factor and scar formation in the cornea

Transforming growth factor beta(1) (TGF-beta(1)) plays an important role in corneal scar formation, mediated by connective tissue growth factor (CTGF). This study was designed to investigate the effect of c-Jun N-terminal kinase (JNK) 1 and 2 on TGF-beta(1)-regulated CTGF gene expression and corneal scar formation in telomerase-immortalized human corneal stroma fibroblast (THSF) cells. The effects of CTGF, TGF-beta(1) and a JNK inhibitor (SP600125) on the proliferation of THSF cells were studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Both CTGF and TGF-beta(1) increased THSF cell proliferation and SP600125 inhibited this effect. Immunofluorescence analysis showed that TGF-beta(1) stimulated the activation of JNK1/2 and induced cell migration, effects that were inhibited by SP600125. Analysis by real-time reverse transcription-polymerase chain reaction showed that the mRNA levels of the genes for CTGF, fibronectin and collagen Ialpha(1) in wound and corneal scar formation were reduced by SP600125 pre-treatment.

Connective tissue growth factor hammerhead ribozyme attenuates human hepatic stellate cell function

AIM: To determine the effect of hammerhead ribozyme targeting connective tissue growth factor (CCN2) on human hepatic stellate cell (HSC) function.

METHODS: CCN2 hammerhead ribozyme cDNA plus two self-cleaving sequences were inserted into pTriEx2 to produce pTriCCN2-Rz. Each vector was individually transfected into cultured LX-2 human HSCs, which were then stimulated by addition of transforming growth factor (TGF)-β1 to the culture medium. Semi-quantitative RT-PCR was used to determine mRNA levels for CCN2 or collagen I, while protein levels of each molecule in cell lysates and conditioned medium were measured by ELISA. Cell-cycle progression of the transfected cells was assessed by flow cytometry.

RESULTS: In pTriEx2-transfected LX-2 cells, TGF-β1 treatment caused an increase in the mRNA level for CCN2 or collagen I, and an increase in produced and secreted CCN2 or extracellular collagen I protein levels. pTriCCN2-Rz-transfected LX-2 cells showed decreased basal CCN2 or collagen mRNA levels, as well as produced and secreted CCN2 or collagen I protein. Furthermore, the TGF-β1-induced increase in mRNA or protein for CCN2 or collagen I was inhibited partially in pTriCCN2-Rz-transfected LX-2 cells. Inhibition of CCN2 using hammerhead ribozyme cDNA resulted in fewer of the cells transitioning into S phase.

CONCLUSION: Endogenous CCN2 is a mediator of basal or TGF-β1-induced collagen I production in human HSCs and regulates entry of the cells into S phase.

Immunohistochemical Localization of EGF, TGF-α, TGF-β, and Their Receptors in Rat Corneas During Healing of Excimer Laser Ablation

PURPOSE

Members of the epidermal growth factor (EGF) and transforming growth factor beta (TGF-beta) families of growth factors and receptors are known to regulate key aspects of corneal wound healing, including epithelial migration and scar formation. To further understand their roles, mRNA levels were measured and proteins were immunolocalized in rat corneas at multiple time points during healing of excimer laser ablation injury.

METHODS

Excimer laser photoablation was performed to a depth of 50 microm on rat corneas. Levels of mRNAs for EGF, TGF-alpha, TGF-beta isoforms 1, 2, and 3, and their receptors (EGF-R and TGFbeta-IIR) were measured by quantitative RT-PCR on days 0, 1.5, 7, 21, 42, and 91 after ablation. Immunohistochemical localization of the growth factors and their receptors was performed on days 0, 7, and 21 in corneal sections.

RESULTS

Levels of EGF mRNA remained stable in rat corneas after ablation (68 +/- 12 copies/cell, mean +/- SD), whereas levels of TGF-alpha mRNA progressively increased sixfold to a maximum at day 42 (300 copies/cell) then slightly decreased on day 91. Levels of EGF-R mRNA rapidly increased 60-fold on day 7 compared with day 0 (571 vs. 9 copies/cell) then decreased sixfold above baseline at day 91. Levels of TGF-beta1 mRNA remained stable (36 +/- 10 copies/cell), whereas levels of TGF-beta2 and TGF-beta3 mRNAs peaked on day 21 (300-fold and 25-fold increase) and remained elevated through day 91. Levels of TGFbeta-IIR mRNA showed a similar pattern. Immunostaining of all the growth factors and receptors was primarily in basal layers of epithelial cells in uninjured cornea and during healing. Intensity of immunostaining for TGF-beta1, TGFbeta-IR, and TGFbeta-IIR increased appreciably in the basal epithelial layers after ablation.

CONCLUSIONS

Levels of mRNAs for several key members of the EGF and TGF-beta systems increase during corneal wound healing. In addition, the proteins are primarily localized in basal layers of epithelial cells, which suggest these cells are active in synthesizing autocrine and paracrine growth factors that modulate corneal wound healing.

Strategies for blocking the fibrogenic actions of connective tissue growth factor (CCN2): From pharmacological inhibition in vitro to targeted siRNA therapy in vivo

Connective tissue growth factor (CCN2) is a major pro-fibrotic factor that frequently acts downstream of transforming growth factor beta (TGF-beta)-mediated fibrogenic pathways. Much of our knowledge of CCN2 in fibrosis has come from studies in which its production or activity have been experimentally attenuated. These studies, performed both in vitro and in animal models, have demonstrated the utility of pharmacological inhibitors (e.g. tumor necrosis factor alpha (TNF-alpha), prostaglandins, peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists, statins, kinase inhibitors), neutralizing antibodies, antisense oligonucleotides, or small interfering RNA (siRNA) to probe the role of CCN2 in fibrogenic pathways. These investigations have allowed the mechanisms regulating CCN2 production to be more clearly defined, have shown that CCN2 is a rational anti-fibrotic target, and have established a framework for developing effective modalities of therapeutic intervention in vivo.

Connective tissue growth factor inhibits adipocyte differentiation

Adipocyte differentiation is a key process implicated in the pathogenesis of obesity and insulin resistance. Its regulation is triggered by a cascade of transcription factors, including the CCAAT/enhancer binding proteins (C/EBPs) and peroxisome proliferator-activated receptor-gamma (PPARgamma). Growth factors such as transforming growth factor-beta1 (TGF-beta1) are known to inhibit adipocyte differentiation in vitro, via the C/EBP pathway, and in vivo, but whether a downstream mediator of TGF-beta1, connective tissue growth factor (CTGF), also known as CCN2, has a similar role is unknown. Mouse 3T3-L1 cells were differentiated into adipocytes by using standard methods, and effects and regulation of CTGF were studied. Intervention with recombinant human CTGF during differing stages of differentiation caused an inhibition in the development of the adipocyte phenotype, according to the gene expression of the differentiation markers adiponectin and PPARgamma, as well as suppression of lipid accumulation and expression of the lipogenic enzyme glycerol-3-phosphate dehydrogenase. Whereas CTGF gene expression promptly fell by 90% as 3T3-L1 preadipocytes differentiated into mature adipocytes, CTGF mRNA expression was induced by added TGF-beta1. CTGF applied to cells early in the course of differentiation inhibited total cell protein levels and nuclear localization of the beta-isoform of C/EBP (C/EBP-beta) and, subsequently, total cell C/EBP-alpha levels. CTGF also inhibited the adipocyte differentiation program in primary cultures of mouse preadipocytes. Expression of CTGF mRNA was twofold higher in the central fat depots of mice compared with subcutaneous fat, suggesting a potential role for CTGF in vivo. In summary, these data show that CTGF inhibits the adipocyte differentiation program.

TGFbeta stimulated re-epithelialisation is regulated by CTGF and Ras/MEK/ERK signalling

The complex mechanisms by which transforming growth factor beta (TGFbeta) regulate re-epithelialisation following injury of stratified epithelia are not fully understood. TGFbeta signals via binding to distinct receptors activating downstream effectors, including Smads which initiate transcription of target genes. However, studies have shown that TGFbeta can also signal independently of Smads through MAPK pathways, demonstrating the diversity of TGFbeta signalling. Connective tissue growth factor (CTGF) is strongly induced by and acts downstream of TGFbeta causing pathophysiology in tissues by inducing matrix deposition, conversion of fibroblasts into contractile myofibroblasts (e.g. dermis and corneal stroma) and stimulation of epithelial-to-mesenchymal transition (e.g. kidney and lung) all of which are known to cause fibrosis. However, a role for CTGF in epithelial cell function which does not involve direct contribution to fibrosis has not been demonstrated. We show for the first time that synthesis of CTGF in cultures of human corneal epithelial cells is induced by TGFbeta through the Ras/MEK/ERK MAPK signalling pathway and that this is required for re-epithelialisation to occur through cell migration. These data reveal a novel function for CTGF in the regulation of epithelial tissue repair beyond its established role in fibrosis, and further highlight the complexity of TGFbeta regulation of epithelial cell function.

Intervention of geminiviral replication in yeast by ribozyme mediated downregulation of its Rep protein

Geminiviruses pose serious threat to many economically important crops such as mungbean, tomato, cotton, etc. To devise a specific antiviral strategy at the viral DNA replication level, a hammerhead ribozyme was directed against the mRNA of the replication initiator protein (Rep). Rep is the most important viral protein for the DNA replication of the Mungbean yellow mosaic India virus (MYMIV), a member of the Geminiviridae family. The ribozyme showed approximately 33% cleavage activity on synthetic rep transcript within 1h under in vitro conditions, whereas the mutant ribozyme, designed to lack the catalytic activity but target the same site, showed no cleavage. The in vivo efficiency of ribozyme was evaluated in Saccharomyces cerevisiae as it can act as a surrogate host for replication of the MYMIV-DNA and lacks RNAi machinery. In the presence of the ribozyme, growth of the yeast cells that are dependent on geminiviral replication was inhibited by 30% and cellular generation time was increased by 2h. The RT-PCR analysis showed a maximum of about 50% reduction in the rep mRNA level in presence of the ribozyme compared to its noncatalytic mutant control. About 65% decrease in geminiviral DNA replication was observed due to the downregulation of replication initiator protein by the ribozyme. These results raise the possibility of engineering resistance to geminiviruses employing the ribozyme approach.

Connective tissue growth factor (CTGF) acts as a downstream mediator of TGF-beta1 to induce mesenchymal cell condensation

Mesenchymal cell (MC) condensation or the aggregation of MCs precedes chondrocyte differentiation and is required for subsequent cartilage formation during endochondral ossification. In this study, we used micromass cultures of C3H10T1/2 cells as an in vitro model system for studying MC condensation and the events important for this process. Transforming growth factor beta1 (TGF-beta1) served as the initiator of MC condensation in our model system and we were interested in determining whether CTGF functions as a downstream mediator of TGF-beta1. CTGF is a matricellular protein that has been found to be expressed in MC condensations and in the perichondrium. Micromass cultures of C3H10T1/2 cells condensed under TGF-beta1 stimulation concomitant with dramatic up-regulation of CTGF mRNA and protein levels. CTGF silencing by either CTGF siRNA or CTGF antisense oligonucleotide approaches showed that TGF-beta1-induced condensation was CTGF dependent. Furthermore, silencing of CTGF expression resulted in significant reductions in cell proliferation and migration, events that are crucial during MC condensation. In addition, up-regulation of Fibronectin (FN) and suppression of Sox9 expression by TGF-beta1 was also found to be mediated by CTGF. Immunofluorescence of developing mouse vertebrae showed that CTGF, TGF-beta1 and FN were co-expressed in condensations of MCs, while Sox9 expression was low at this stage. During subsequent chondrogenesis, Sox9 expression was high in chondrocytes while CTGF expression was limited to the perichondrium. Thus, CTGF is an essential downstream mediator of TGF-beta1-induced MC condensation through its effects on cell proliferation and migration. CTGF is also involved in up-regulating FN and suppressing Sox9 expression during TGF-beta1 induced MC condensation.

Suppression of Cell Proliferation and Signaling Transduction by Connective Tissue Growth Factor in Non–Small Cell Lung Cancer Cells

Connective tissue growth factor (CTGF) is a secreted protein that belongs to CCN family. The proteins in this family are implicated in various biological processes, such as angiogenesis, adhesion, migration, and apoptosis. In this study, we explored the roles of CTGF in lung tumorigenesis. The expression levels of CTGF in 58 lung cancer samples were reduced by >2 fold in 57% of the samples compared with matched normal samples using real-time reverse transcription-PCR. These results were confirmed by immunohistochemical staining for CTGF in normal lung epithelia and lung cancer. Cellular proliferation was inhibited in non-small cell lung cancer (NSCLC) cell lines NCI-H460, NCI-H520, NCI-H1299, and SK-MES-1 by CTGF overexpression. Partially purified CTGF suppressed lung cancer cell growth. The growth inhibition caused by CTGF overexpression was associated with growth arrest at G(0)-G(1) and prominent induction of p53 and ADP ribosylation factor. Most interestingly, overexpression of CTGF suppressed insulin-like growth factor-I-dependent Akt phosphorylation and epidermal growth factor-dependent extracellular signal-regulated kinase 1/2 phosphorylation. In summary, NSCLC cells expressed decreased levels of CTGF compared with normal lung cells; this lower expression has an effect on lung cancer cell proliferation and its cellular response to growth factors. Our data suggest that CTGF may behave as a secreted tumor suppressor protein in the normal lung, and its expression is suppressed in many NSCLCs.

VEGF, VEGFR-1, and CTGF cell densities in tendon are increased with cyclical loading: An in vivo tendinopathy model

Tendon injuries can occur in athletes and workers whose tasks involve repetitive, high-force hand activities, but the early pathophysiologic processes of tendinopathy are not well known. The purpose of this animal study was to evaluate the effects of cyclical tendon loading on the densities of cells producing growth factors such as vascular endothelial growth factor (VEGF), its receptor, vascular endothelial growth factor receptor 1 (VEGFR-1), and connective tissue growth factor (CTGF) in the Flexor Digitorum Profundus (FDP) tendon at the epicondyle. The FDP muscles of nine New Zealand rabbits were electrically stimulated to contract repetitively for 80 h of cumulative loading over 14 weeks. The contralateral limbs served as controls. The tendons at the medial epicondyle insertion sites were harvested, and sections were immunostained with antibodies directed against VEGF, VEGFR-1, or CTGF. Positive-staining cells were counted in six regions of interest: three along the enthesis, and three corresponding regions 1500 microns distal to the enthesis. VEGF (p = 0.0001), VEGFR-1 (p = 0.046), and CTGF (p = 0.0001) cell densities were increased in the tendon of the loaded limb compared to the nonloaded limb. In addition, regional differences in VEGF, VEGFR-1, and CTGF cell densities were found. VEGF, VEGFR-1, and CTGF are increased in tendon experiencing cyclical loading and may play a role in the early vascular changes in the progression to tendinosis.

Intrastriatal rAAV-mediated delivery of anti-huntingtin shRNAs induces partial reversal of disease progression in R6/1 Huntington's disease transgenic mice

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by the presence of an abnormally expanded polyglutamine domain in the N-terminus of huntingtin. We developed a recombinant adeno-associated viral serotype 5 (rAAV5) gene transfer strategy to posttranscriptionally suppress the levels of striatal mutant huntingtin (mHtt) in the R6/1 HD transgenic mouse via RNA interference. Transient cotransfection of HEK293 cells with plasmids expressing a portion of human mHtt derived from R6/1 transgenic HD mice and a short-hairpin RNA directed against the 5' UTR of the mHtt mRNA (siHUNT-1) resulted in reduction in the levels of mHtt mRNA (-75%) and protein (-60%). Long-term in vivo rAAV5-mediated expression of siHUNT-1 in the striatum of R6/1 mice reduced the levels of mHtt mRNA (-78%) and protein (-28%) as determined by quantitative RT-PCR and Western blot analysis, respectively. The reduction in mHtt was concomitant with a reduction in the size and number of neuronal intranuclear inclusions and a small but significant normalization of the steady-state levels of preproenkephalin and dopamine- and cAMP-responsive phosphoprotein 32 kDa mRNA. Finally, bilateral expression of rAAV5-siHUNT-1 resulted in delayed onset of the rear paw clasping phenotype exhibited by the R6/1 mice. These results suggest that a reduction in the levels of striatal mHtt can ameliorate the HD phenotype of R6/1 mice.

Effect of ribozyme against transforming growth factorbeta1 on biological character of activated HSCs

Transforming growth factorbeta1 (TGFbeta1) is considered to be the principal contributor to liver fibrosis. So in this study the ribozymes against TGFbeta1 were designed. The in vitro cleavage activities of the ribozymes were assayed through incubation of (32)p-labeled target RNAs and (32)p-labeled ribozymes in different conditions. HSC-T6 cells were transfected with the eukaryotic constructs encoding ribozyme and disable ribozyme, then the stable cell clones were used to evaluate its antifibrotic characteristic through the effect of ribozyme on biological character of activated hepatic stellate cells (HSCs). The results demonstrated that two ribozymes (Rz803 and Rz1395) could cleave target RNAs into expected products effectively, Rz803 possessed better cleavage activity in vitro. Stable transfection of Rz803 into activated HSCs reduced TGFbeta1 expression in mRNA and protein level efficiently. The further studies demonstrated that Rz803 reduced deposition of collagen I, suppressed HSC proliferation, but had no effect on HSC activation in transfected HSC-T6 cells. Therefore, it indicated that Rz803 could reverse the character of activated HSCs by down-regulating TGFbeta1 expression efficiently and diminishing TGFbeta1 signaling underlying activation of hepatic stellate cells. As the consequence, it would provide a potential therapeutic approach for liver fibrosis.