PEDF-derived peptide inhibits corneal angiogenesis by suppressing VEGF expression

Pigment epithelium-derived factor (PEDF) a glycoprotein that belongs to the superfamily of serine protease inhibitors, has been recently shown to be the most potent inhibitor of angiogenesis in the mammalian eye. However, which active domain of PEDF protein could be involved in its anti-angiogenic properties remains unknown. Therefore, in this study, we examined which PEDF-derived synthetic peptides could inhibit corneal neovascularization induced by chemical cauterization in vivo. Rats treated with topical application of PEDF protein had 31% less corneal neovascularization at day 7 after the injury than phosphate-buffered saline (PBS)-treated rats. P5-2 and P5-3 peptides (residues 388-393 and 394-400 of PEDF protein, respectively) significantly suppressed the corneal neovascularization after chemical cauterization at day 7, and its anti-angiogenic potential was almost equal to that of full-length PEDF protein. Further, full-length PEDF protein and P5-3 peptide significantly decreased 8-hydroxy-2'-deoxyguanosine and vascular endothelial growth factor (VEGF) levels in the corneal. Our present study suggests that PEDF-derived synthetic peptide, P5-3 could inhibit the corneal neovascularization induced by chemical cauterization in rats by suppressing VEGF expression via its anti-oxidative properties.     

Recombinant vascular basement-membrane-derived multifunctional peptide inhibits angiogenesis and growth of hepatocellular carcinoma

AIM： To investigate the anti-angiogenic and antitumor activities of recombinant vascular basement membrane-derived multifunctional peptide （rVBMDMP） in hepatocellular carcinoma （HCC）. METHODS： HepG2, Bel-7402, Hep-3B, HUVE-12 and L-02 cell lines were cultured in vitro and the inhibitory effect of rVBMDMP on proliferation of cells was detected by MTT assay. The in vivo antitumor efficacy of rVBMDMP on HCC was assessed by HepG2 xenografts in nude mice. Distribution of rVBMDMP, mechanism by which the growth of HepG2 xenografts is inhibited, and microvessel area were observed by proliferating cell nuclear antigen （PCNA） and CD31 immunohistochemistry. RESULTS： MTT assay showed that rVBMDMP markedly inhibited the proliferation of human HCC （HepG2, Bel-7402, Hep-3B） cells and human umbilical vein endothelial （HUVE-12） cells in a dose-dependent manner, with little effect on the growth of L-02 cells. When the ICs0 was 4.68, 7.65, 8.96, 11.65 and 64.82 μmol/L, respectively, the potency of rVBMDMP to HepG2 cells was similar to 5-fluorouracil （5-FU） with an IC50 of 4.59 μmol/L. The selective index of cytotoxicity to HepG2 cells of rVBMDMP was 13.8 （64.82/4.68）, which was higher than that of 5-FU [SI was 1.9 （8.94/4.59）]. The VEGF-targeted recombinant humanized monoclonal antibody bevacizumab （100 mg/L） did not affect the proliferation of HepG2, Bel-7402, Hep-3B and L-02 cells, but the growth inhibitory rate of bevacizumab （100 mg/L） to HUVE-12 cells was 87.6% ± 8.2%. AIternis diebus intraperitoneal injection of rVBMDMP suppressed the growth of HepG2 xenografts in a dose-dependent manner, rVBMDMP （1, 3, 10 mg/kg） decreased the tumor weight by 12.6%, 55.9% and 79.7%, respectively, compared with the vehicle control. Immunohistochemical staining of rVBMDMP showed that the positive area rates （2.2% ± 0.73%, 4.5%± 1.3% and 11.5% ±3.8%） in rVBMDMP treated group （1, 3, 10 mg/kg） were significantly higher than that （0.13% ± 0.04%） in the control group （P 〈 0.01）. The positive area rates （19.0% ± 5.7%, 12.2% ± 3.5% and 5.2% ±1.6% ） of PCNA in rVBMDMP treated group （1, 3, 10 mg/kg） were significantly lower than that （29.5% ± 9.4%） in the control group （P 〈 0.05）. rVBMDMP at doses of 1, 3 and 10 mg/kg significantly reduced the tumor microvessel area levels （0.26%± 0.07%, 0.12% ± 0.03% and 0.05% ± 0.01% vs 0.45% ± 0.15%） in HepG2 xenografts （P 〈 0.01）, as assessed by CD31 staining. CONCLUSION： rVBMDMP has effective and unique anti-tumor properties, and is a promising candidate for the development of anti-tumor drugs.     

A dominant-negative mutant of Max that inhibits sequence-specific DNA binding by Myc proteins.

Myc proteins are basic helix-loop-helix/leucine-zipper proteins that bind to specific DNA sequences. In vivo, Myc proteins have been found associated with Max, another basic helix-loop-helix/leucine-zipper protein. However, it is not known to what extent the dimerization of Myc with Max is required for the manifestation of the Myc-induced phenotype. To investigate this, we constructed a dominant-negative mutant of Max, named dMax, that inhibits sequence-specific DNA binding of Myc proteins. Using a rat neuroblastoma model system, we show that dMax reverts N-Myc-induced changes in cellular gene expression. A control mutant of dMax that contains a proline residue in the leucine-zipper region was unable to bind to N-Myc and did not revert the N-Myc-induced changes in cellular gene expression. These data support the hypothesis that N-Myc affects neuroblastoma gene expression through the formation of a DNA-binding heterodimeric complex with Max in vivo.     

A fibronectin fragment inhibits tumor growth, angiogenesis, and metastasis

We have shown previously that a polymeric form of fibronectin is strongly antimetastatic when administered systemically to tumor-bearing mice. The polymeric fibronectin, sFN, is formed in vitro by treating soluble fibronectin with a 76-aa peptide, III1-C, which is derived from the first type III repeat in fibronectin. Here we show that the III1-C peptide and sFN also reduce tumor growth in mice, and that this effect correlates with a low density of blood vessels in the tumors of the treated mice. III1-C also polymerized fibrinogen, and the fibrinogen polymer, sFBG, had antitumor and antiangiogenic effects similar to those of sFN. Mice that had been injected s.c. with three different types of human tumor cells and treated with biweekly i.p. injections of III1-C, sFN, or sFBG over a 5-week period had tumors that were 50-90% smaller than those of control mice. Blood vessel density in the tumors of the treated mice was reduced by 60-80% at the end of the experiment. Xenograft tumors from a human breast carcinoma line (MDA-MB-435) were particularly susceptible to these treatments. Metastasis into the lungs from the primary s.c. tumors also was inhibited in the mice treated with III1-C and the two polymers. The III1-C peptide is an antiangiogenic and antimetastatic agent. Because of its ability to suppress tumor growth, angiogenesis, and metastasis, we have named the III1-C peptide anastellin [from anastello (Greek), inhibit, force a retreat].     

A cell penetrating peptide derived from azurin inhibits angiogenesis and tumor growth by inhibiting phosphorylation of VEGFR-2, FAK and Akt

Amino acids 50-77 (p28) of azurin, a 128 aa cupredoxin isolated from Pseudomonas aeruginosa, is essentially responsible for azurin's preferential penetration of cancer cells. We now report that p28 also preferentially penetrates human umbilical vein endothelial cells (HUVEC), co-localized with caveolin-1 and VEGFR-2, and inhibits VEGF- and bFGF-induced migration, capillary tube formation and neoangiogenesis in multiple xenograft models. The antiangiogenic effect of p28 in HUVEC is associated with a dose-related non-competitive inhibition of VEGFR-2 kinase activity. However, unlike other antiangiogenic agents that inhibit the VEGFR-2 kinase, p28 decreased the downstream phosphorylation of FAK and Akt that normally precedes cellular repositioning of the cytoskeletal (F-actin), focal adhesion (FAK and paxillin), and cell to cell junction protein PECAM-1, inhibiting HUVEC motility and migration. The decrease in pFAK and pAkt levels suggests that p28 induces a pFAK-mediated loss of HUVEC motility and migration and a parallel Akt-associated reduction in cell matrix attachment and survival. This novel, direct antiangiogenic effect of p28 on endothelial cells may enhance the cell cycle inhibitory and apoptotic properties of this prototype peptide on tumor cell proliferation as it enters a Phase II clinical trial.     

A DNA vaccine targeting angiomotin inhibits angiogenesis and suppresses tumor growth

Endogenous angiogenesis inhibitors have shown promise in preclinical trials, but clinical use has been hindered by low half-life in circulation and high production costs. Here, we describe a strategy that targets the angiostatin receptor angiomotin (Amot) by DNA vaccination. The vaccination procedure generated antibodies that detected Amot on the endothelial cell surface. Purified Ig bound to the endothelial cell membrane and inhibited endothelial cell migration. In vivo, DNA vaccination blocked angiogenesis in the matrigel plug assay and prevented growth of transplanted tumors for up to 150 days. We further demonstrate that a combination of DNA vaccines encoding Amot and the extracellular and transmembrane domains of the human EGF receptor 2 (Her-2)/neu oncogene inhibited breast cancer progression and impaired tumor vascularization in Her-2/neu transgenic mice. No toxicity or impairment of normal blood vessels could be detected. This work shows that DNA vaccination targeting Amot may be used to mimic the effect of angiostatin.     

A peptide derived from the non-receptor-binding region of urokinase plasminogen activator inhibits glioblastoma growth and angiogenesis in vivo in combination with cisplatin

The urokinase plasminogen activator system is involved in angiogenesis and tumor growth of malignant gliomas, which are highly neovascularized and so may be amenable to antiangiogenic therapy. In this paper, we describe the activity of A6, an octamer capped peptide derived from the non-receptor-binding region of urokinase plasminogen activator. A6 inhibited human microvascular endothelial cell migration but had no effect on the proliferation of human microvascular endothelial cells or U87MG glioma cells in vitro. In contrast, A6 or cisplatin (CDDP) alone suppressed subcutaneous tumor growth in vivo by 48% and 53%, respectively, and, more strikingly, the combination of A6 plus CDDP inhibited tumor growth by 92%. Such combination treatment also greatly reduced the volume of intracranial tumor xenografts and increased survival of tumor-bearing animals when compared with CDDP or A6 alone. Tumors from the combination treatment group had significantly reduced neovascularization, suggesting a mechanism involving A6-mediated inhibition of endothelial cell motility, thereby eliciting vascular sensitivity to CDDP-mediated toxicity. These data suggest that the combination of an angiogenesis inhibitor that targets endothelial cells with a cytotoxic agent may be a useful therapeutic approach.     

Expression of dominant-negative Dmp53 in the adult fly brain inhibits insulin signaling

In Drosophila melanogaster, p53 (Dmp53) is an important mediator of longevity. Expression of dominant-negative (DN) forms of Dmp53 in adult neurons, but not in muscle or fat body cells, extends lifespan. The lifespan of calorie-restricted flies is not further extended by simultaneously expressing DN-Dmp53 in the nervous system, indicating that a decrease in Dmp53 activity may be a part of the CR lifespan-extending pathway in flies. In this report, we show that selective expression of DN-Dmp53 in only the 14 insulin-producing cells (IPCs) in the brain extends lifespan to the same extent as expression in all neurons and this lifespan extension is not additive with CR. DN-Dmp53-dependent lifespan extension is accompanied by reduction of Drosophila insulin-like peptide 2 (dILP2) mRNA levels and reduced insulin signaling (IIS) in the fat body, which suggests that Dmp53 may affect lifespan by modulating insulin signaling in the fly.     

Directed expression of dominant-negative p73 enables proliferation of cardiomyocytes in mice

Previous studies have shown that p53 plays an important role in maintaining cell cycle arrest of cardiomyocytes, which might account for the inability of human hearts to regenerate adequately after injury. Therefore, inhibition of p53 represents an attractive strategy to restore cell cycle progression in cardiomyocytes although such an approach is hampered by the potential danger of concomitant tumor induction. During normal development, N-terminal truncated isoforms of the p53-related protein p73 are naturally occurring antagonists of p53 and p73, which are not related to tumor induction. We have generated recombinant adenoviruses encoding dominant-interfering p73 (Ad-p73DD) to inhibit p53/p73 in murine hearts at different developmental stages. We found that the expression of p73DD(wt) in newborn mice led to the increase of the relative heart weights after 14 days which is paralleled by a significant increase of proliferating cardiomyocytes as seen by ICC (BrdU-incorporation, phosphorylation of histone3, expression of AuroraB) without induction of apoptosis. Stimulation of cell cycle progression in cardiomyocytes went along with a significant down-regulation of the p53-dependent cdk-inhibitor p21WAF both on mRNA and protein level. Furthermore, mRNA levels and protein expression of D-type cyclins and cyclins A, B2, and E were selectively increased after expression of p73DD. We further show that the cell cycle entry of cardiomyocytes is not restricted to neonatal hearts but is also found in adult mouse hearts 5 days after intramyocardial injection of Ad-p73DD. Taken together we reason that directed expression of dominant-negative p73 might be utilized to stimulate proliferation of cardiomyocytes to improve cardiac regeneration.     

Bleomycin sensitivity of mice expressing dominant-negative p53 in the lung epithelium

The chemotherapeutic drug bleomycin causes DNA damage and apoptosis in the lungs of mice within hours of endotracheal instillation followed by inflammation and fibrosis weeks later. The p53 tumor suppressor protein mediates cellular responses to DNA damage, including induction of apoptosis, but the effects of p53 activation in the various cell types of the lung during bleomycin-induced pulmonary fibrosis remain unclear. We show here that a transgene with a dominant-negative mutant form of human p53 expressed from the surfactant protein C promoter sensitizes mice to bleomycin-induced lung injury. The bleomycin-exposed transgenic animals display more severe lung pathology with associated collagen deposition and more pronounced lung eosinophilia than simultaneously exposed nontransgenic littermates. These observations suggest that compromising p53 function in the alveolar epithelium impairs recovery of the lung from bleomycin-induced injury.     

Neridronate inhibits angiogenesis in vitro and in vivo

The effects of the amino-bisphosphonate neridronate on endothelial cell functions involved in angiogenesis, namely, proliferation and morphogenesis on Matrigel were tested in vitro, whereas its effects on angiogenesis were studied in vivo, by using the chick embryo chorioallantoic membrane (CAM) assay. In vitro, neridronate inhibited endothelial cell proliferation in a dose-dependent fashion, peaking at 30 μM. At the same concentration, neridronate inhibited fibroblast growth factor-2 (FGF-2)-induced capillary-like tube formation in the morphogenesis assay on Matrigel. In vivo, when tested in the CAM assay, neridronate again displayed the capability to inhibit FGF-2-induced angiogenesis. Overall, these results suggest that anti-angiogenesis by neridronate could be used to treat a wide spectrum of angiogenesis-dependent diseases, including certain chronic inflammatory diseases and cancer.     

A human claudin-1-derived peptide inhibits hepatitis C virus entry

Hepatitis C virus (HCV) entry is a complicated process that requires multiple host factors, such as CD81, scavenger receptor BI, claudin-1 (CLDN1), and occludin. The interaction of virus and cellular entry factors represents a promising target for novel anti-HCV drug development. In this study, we sought to identify peptide inhibitors for HCV entry by screening a library of overlapping peptides covering the four above-mentioned entry factors. An 18-amino acid peptide (designated as CL58) that was derived from the CLDN1 intracellular and first transmembrane region inhibited both de novo and established HCV infection in vitro. Unlike previously reported peptides corresponding to CLDN1 extracellular loops, CL58 did not alter the normal distribution of CLDN1 and was not cytotoxic in vitro at concentrations nearly 100-fold higher than the effective antiviral dose. The inhibitory effect of CL58 appeared to occur at a late step during viral entry, presumably after initial binding. Finally, overexpressed CL58 was able to interact with HCV envelope proteins. CONCLUSION: We identified a novel CLDN1-derived peptide that inhibits HCV entry at a postbinding step. The findings expand our knowledge of the roles that CLDN1 play in HCV entry and highlight the potential for developing a new class of inhibitors targeting the viral entry process.