Anti-SPARC oligopeptide inhibits laser-induced CNV in mice

Potential Mechanisms of Triptolide against Diabetic Cardiomyopathy Based on Network Pharmacology Analysis and Molecular Docking

The incidence of heart failure was significantly increased in patients with diabetic cardiomyopathy (DCM). The therapeutic effect of triptolide on DCM has been reported, but the underlying mechanisms remain to be elucidated. This study is aimed at investigating the potential targets of triptolide as a therapeutic strategy for DCM using a network pharmacology approach. Triptolide and its targets were identified by the Traditional Chinese Medicine Systems Pharmacology database. DCM-associated protein targets were identified using the comparative toxicogenomics database and the GeneCards database. The networks of triptolide-target genes and DCM-associated target genes were created by Cytoscape. The common targets and enriched pathways were identified by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The gene-gene interaction network was analyzed by the GeneMANIA database. The drug-target-pathway network was constructed by Cytoscape. Six candidate protein targets were identified in both triptolide target network and DCM-associated network: STAT3, VEGFA, FOS, TNF, TP53, and TGFB1. The gene-gene interaction based on the targets of triptolide in DCM revealed the interaction of these targets. Additionally, five key targets that were linked to more than three genes were determined as crucial genes. The GO analysis identified 10 biological processes, 2 cellular components, and 10 molecular functions. The KEGG analysis identified 10 signaling pathways. The docking analysis showed that triptolide fits in the binding pockets of all six candidate targets. In conclusion, the present study explored the potential targets and signaling pathways of triptolide as a treatment for DCM. These results illustrate the mechanism of action of triptolide as an anti-DCM agent and contribute to a better understanding of triptolide as a transcriptional regulator of cytokine mRNA expression.

Targeted Delivery of FLT-Morpholino Using Cyclic RGD Peptide

Purpose

We previously showed that intravitreal injection of the sFLT morpholino-oligomer (FLT-MO) suppresses laser-induced choroidal neovascularization (CNV) in mice by decreasing the membrane bound form of Flt-1 while increasing the soluble form of Flt-1 via alternative splicing shift. In this study, we examined whether cyclic RGD peptide (cRGD) can promote morpholino-oligomer accumulation in CNV following tail vein injection, and whether systemic cRGD conjugated FLT-MO (cRGD-FLT-MO) suppresses CNV growth.

Methods

cRGD conjugated fluorescent morpholino-oligomer (cRGD-F-MO) was injected via tail vein into mice with previous retinal laser photocoagulation and examined for cRGD-F-MO accumulation in CNV. To examine whether cRGD-FLT-MO suppresses CNV growth, mice were tail-vein injected with cRGD-FLT-MO, cRGD conjugated standard morpholino-oligomer (cRGD-STD-MO), or Dulbecco's Phosphate-Buffered Saline (DPBS) 1 and 4 days postlaser photocoagulation. Seven days postlaser photocoagulation, eyes were harvested and laser CNV was stained with isolectin GS-IB4, allowing quantification of CNV size by confocal microscopy.

Results

cRGD-F-MO accumulation in CNV commenced immediately after tail vein injection and could be observed even 1 day after injection. cRGD-FLT-MO tail vein injection significantly suppressed CNV size (2.7 × 10⁵ ± 0.3 × 10⁵ μm³, P < 0.05 by Student's t-test) compared with controls (DPBS: 5.1 × 10⁵ ± 0.6 × 10⁵ μm³ and cRGD-STD-MO: 5.5 × 10⁵ ± 0.8 × 10⁵ μm³).

Conclusions

cRGD peptide facilitates morpholino-oligomer accumulation in CNV following systemic delivery. cRGD-FLT-MO suppressed CNV growth after tail-vein injection, demonstrating the potential utility of cRGD peptide for morpholino-oligomer delivery to CNV.

Translational Relevance

Current therapy for neovascular age-related macular degeneration involves intravitreal injection of anti-vascular endothelial growth factor drugs. Our results indicate that CNV can be treated systemically, thus eliminating risks and hazards associated with intravitreal injection.

Caffeic acid phenethyl ester reduces the secretion of vascular endothelial growth factor through the inhibition of the ROS, PI3K and HIF-1α signaling pathways in human retinal pigment epithelial cells under hypoxic conditions

Choroidal neovascularization (CNV) can lead to progressive and severe visual loss. Vascular endothelial growth factor (VEGF) promotes the development of CNV. Caffeic acid phenethyl ester (CAPE), a biologically active component of the honeybee (Apis mellifera) propolis, has been demonstrated to have several interesting biological regulatory properties. The objective of this study was to determine whether treatment with CAPE results in the inhibition of the production of vascular endothelial growth factor (VEGF) in retinal pigment epithelial cells (RPE cells) under hypoxic conditions and to explore the possible underlying mechanisms. An in vitro experimental model of hypoxia was used to mimic an ischemic microenvironment for the RPE cells. Human RPE cells (ARPE-19) were exposed to hypoxia with or without CAPE pre-treatment. ARPE-19 cells were used to investigate the pathway involved in the regulation of VEGF production under hypoxic conditions, based on western blot analysis, enzyme-linked immunosorbent assay (ELISA) and electrophoretic mobility shift assay (EMSA). The amount of VEGF released from the hypoxia-exposed cells was significantly higher than that of the normoxic controls. Pre-treatment with CAPE suppressed the hypoxia-induced production of VEGF in the ARPE-19 cells, and this effect was inhibited through the attenuation of reactive oxygen species (ROS) production, and the inhibition of phosphoinositide 3-kinase (PI3K)/AKT and hypoxia-inducible factor-1α (HIF-1α) expression. These in vitro findings suggest that CAPE may prove to be a novel anti-angiogenic agent for the treatment of diseases associated with CNV.

Deletion of SPARC Enhances Retinal Vaso-Obliteration in Mouse Model of Oxygen-Induced Retinopathy

BACKGROUND

Secreted Protein Acidic and Rich in Cysteine (SPARC) is a matricellular protein which is implicated in regulation of angiogenesis.

PURPOSE

To characterize the changes in SPARC expression and effect of its deletion in a mouse model Oxygen Induced Retinopathy (OIR).

MATERIALS AND METHODS

Wild type (wt) and SPARC-deficient mice were subjected to high oxygen (75%) for 5 days (p7-p12) before room air for additional 5 days (p12-p17). Retinas from both groups were flat mounted and retinal vessels were labeled with Isolectin-B4. Areas of Retinal Neovascularization (RNV) and vaso-obliteration were measured by Image-J and normalized to total retinal areas. SPARC expression was analyzed in both groups at p14 and p17 in retinal homogenates and sections by Western Blotting (WB) and immunofluorescence respectively. Human Retinal Endothelial Cells (HRECs) were exposed to hypoxia (1% O2) for 6 hours then SPARC was measured in cell lysate and condition medium by WB and ELISA. Moreover, HRECs were treated with VEGF or SPARC to study their mutual regulatory effect.

RESULTS

SPARC-deficient mice demonstrated significant increase in the vaso-obliteration (p=0.03) and modest increase in RNV compared to the wt control. Retinal levels of SPARC was significantly decreased during OIR at p14 (p=0.01) and partially restored to normal level by p17. Moreover, hypoxia significantly reduced SPARC expression and secretion in HRECs (p=0.001). We noticed a mutual positive regulatory feedback between SPARC and VEGF.

CONCLUSION

SPARC deletion enhances ischemic retinopathy, thus modulation of SPARC expression could be a novel therapeutic approach to prevent pathological RNV.

SPARC/osteonectin is involved in metastatic process to the lung during melanoma progression

The existence of a "metastasis gene signature" that predisposes primary breast cancer cells to metastasize to the lungs has been recently highlighted by gene expression profiling studies. The combination of genes responsible for this process includes genes encoding several metalloproteinases as well as the gene encoding SPARC (secreted protein acidic and rich in cysteine)/osteonectin. SPARC is involved in normal tissue remodeling as it regulates the deposition of extracellular matrix, but also plays a role in neoplastic transformation. Aberrant SPARC expression has been detected both in stromal cells associated with cancer and in cancer cells. The main aim of this study was to investigate whether or not SPARC might be involved in directing metastasis of other types of cancer to the lung. We constructed a tissue microarray containing lung metastases from a variety of primary tumors in different organs and used immunohistochemistry to assess SPARC expression. We found SPARC overexpressed mainly in lung metastases from melanoma. We then assessed the expression of SPARC mRNA and protein in metastatic melanoma from different anatomic sites and in their corresponding primary tumors, and found that it is overexpressed in lung metastases. Our data strongly support the hypothesis that SPARC is involved in directing melanoma metastases specifically to the lung, which underpins its potential as prognostic marker and novel target for specific therapy.

Loss of SPARC protects hematopoietic stem cells from chemotherapy toxicity by accelerating their return to quiescence

Around birth, hematopoietic stem cells (HSCs) expanding in the fetal liver migrate to the developing bone marrow (BM) to mature and expand. To identify the molecular processes associated with HSCs located in the 2 different microenvironments, we compared the expression profiles of HSCs present in the liver and BM of perinatal mice. This revealed the higher expression of a cluster of extracellular matrix-related genes in BM HSCs, with secreted protein acidic and rich in cysteine (SPARC) being one of the most significant ones. This extracellular matrix protein has been described to be involved in tissue development, repair, and remodeling, as well as metastasis formation. Here we demonstrate that SPARC-deficient mice display higher resistance to serial treatment with the chemotherapeutic agent 5-fluorouracil (5-FU). Using straight and reverse chimeras, we further show that this protective effect is not due to a role of SPARC in HSCs, but rather is due to its function in the BM niche. Although the kinetics of recovery of the hematopoietic system is normal, HSCs in a SPARC-deficient niche show an accelerated return to quiescence, protecting them from the lethal effects of serial 5-FU treatment. This may become clinically relevant, as SPARC inhibition and its protective effect on HSCs could be used to optimize chemotherapy schemes.

Dual suppression of hemangiogenesis and lymphangiogenesis by splice-shifting morpholinos targeting vascular endothelial growth factor receptor 2 (KDR)

The KDR gene, which participates in angiogenesis and lymphangiogenesis, produces two functionally distinct protein products, membrane-bound KDR (mbKDR) and its isoform, soluble KDR (sKDR). Since sKDR does not have a tyrosine kinase domain and does not dimerize, it is principally an antagonist of lymphangiogenesis by sequestering VEGF-C. Alternative polyadenylation of exon 30 or intron 13 leads to the production of mbKDR or sKDR, respectively, yet the regulatory mechanisms are unknown. Here we show that an antisense morpholino oligomer directed against the exon 13-intron 13 junction increases sKDR (suppressing lymphangiogenesis) and decreases mbKDR (inhibiting hemangiogenesis). The latent polyadenylation site in intron 13 of KDR is activated by blocking the upstream 5' splicing site with an antisense morpholino oligomer. Intravitreal morpholino injection suppressed laser choroidal neovascularization while increasing sKDR. In the mouse cornea, subconjunctival injection of the morpholino-inhibited corneal angiogenesis and lymphangiogenesis, and suppressed graft rejection after transplantation. Thus, this morpholino can be used for concurrent suppression of hemangiogenesis and lymphangiogenesis. This study offers new insight into the mechanisms and potential therapeutic modulation of alternative polyadenylation.

SPARC modulates expression of extracellular matrix genes in human trabecular meshwork cells

PURPOSE

To investigate the effects of secreted protein acidic and rich in cysteine (SPARC) on the expression of components of the extracellular matrix (ECM) in cultured human trabecular meshwork (TM) cells.

METHODS

Cultured human trabecular cells were transfected with small interfering RNAs (siRNAs) specific for the human SPARC gene. Protein and mRNA expressions of fibronectin (FN) and the α1chains of collagen I and collagen III were quantified.

RESULTS

After silencing of the SPARC gene by transfection of cells with SPARC siRNA, the expression of COL1A1 and COL3A1 mRNAs and proteins was significantly enhanced, as compared to that in the control group (all, p < 0.001). In contrast, SPARC siRNA significantly reduced the expression of FN and SPARC mRNAs and FN protein, as compared to that in the control group (all, p < 0.001.).

CONCLUSIONS

SPARC modulates the expression of several ECM genes in cultured human TM cells.

Retinoid receptors trigger neuritogenesis in retinal degenerations

Anomalous neuritogenesis is a hallmark of neurodegenerative disorders, including retinal degenerations, epilepsy, and Alzheimer's disease. The neuritogenesis processes result in a partial reinnervation, new circuitry, and functional changes within the deafferented retina and brain regions. Using the light-induced retinal degeneration (LIRD) mouse model, which provides a unique platform for exploring the mechanisms underlying neuritogenesis, we found that retinoid X receptors (RXRs) control neuritogenesis. LIRD rapidly triggered retinal neuron neuritogenesis and up-regulated several key elements of retinoic acid (RA) signaling, including retinoid X receptors (RXRs). Exogenous RA initiated neuritogenesis in normal adult retinas and primary retinal cultures and exacerbated it in LIRD retinas. However, LIRD-induced neuritogenesis was partly attenuated in retinol dehydrogenase knockout (Rdh12(-/-)) mice and by aldehyde dehydrogenase inhibitors. We further found that LIRD rapidly increased the expression of glutamate receptor 2 and β Ca(2+)/calmodulin-dependent protein kinase II (βCaMKII). Pulldown assays demonstrated interaction between βCaMKII and RXRs, suggesting that CaMKII pathway regulates the activities of RXRs. RXR antagonists completely prevented and RXR agonists were more effective than RA in inducing neuritogenesis. Thus, RXRs are in the final common path and may be therapeutic targets to attenuate retinal remodeling and facilitate global intervention methods in blinding diseases and other neurodegenerative disorders.