Long-term suppression of ocular neovascularization by intraocular injection of biodegradable polymeric particles containing a serpin-derived peptide.
Aberrant angiogenesis can cause or contribute to a number of diseases such as neovascular age-related macular degeneration (NVAMD). While current NVAMD treatments target angiogenesis, these treatments are not effective for all patients and also require frequent intravitreal injections. New agents and delivery systems to treat NVAMD could be beneficial to many patients. We have recently developed a serpin-derived peptide as an anti-angiogenic agent. Here, this peptide is investigated for activity in human retinal endothelial cells in vitro and for reducing angiogenesis in a laser-induced choroidal neovascularization mouse model of NVAMD in vivo. While frequent intravitreal injections can be tolerated clinically, reducing the number of injections can improve patient compliance, safety, and outcomes. To achieve this goal, and to maximize the in vivo activity of injected peptide, we have developed biodegradable polymers and controlled release particle formulations to extend anti-angiogenic therapy. To create these devices, the anionic peptides are first self-assembled into nanoparticles using a biodegradable cationic polymer and then as a second step, these nanoparticles are encapsulated into biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles. In situ, these particles show approximately zero-order, linear release of the anionic peptide over 200 days. These particles are made of safe, hydrolytically degradable polymers and have low endotoxin. Long-term in vivo experiments in the laser-induced neovascularization model for NVAMD show that these peptide-releasing particles decrease angiogenesis for at least fourteen weeks in vivo following a single particle dose and therefore are a promising treatment strategy for NVAMD.
Synergy between a collagen IV mimetic peptide and a somatotropin-domain derived peptide as angiogenesis and lymphangiogenesis inhibitors
Inhibition of lymphangiogenesis and angiogenesis in breast tumor xenografts and lymph nodes by a peptide derived from transmembrane protein 45A. Lee E, Koskimaki JE, Pandey NB, Popel AS. Neoplasia. 2013 Feb;15(2):112-24.
Angiogenesis is central to many physiological and pathological processes. Here we show two potent bioinformatically-identified peptides, one derived from collagen IV and translationally optimized, and one from a somatotropin domain-containing protein, synergize in angiogenesis and lymphangiogenesis assays including cell adhesion, migration and in vivo Matrigel plugs. Peptide-peptide combination therapies have recently been applied to diseases such as human immunodeficiency virus (HIV), but remain uncommon thus far in cancer, age-related macular degeneration and other angiogenesis-dependent diseases. Previous work from our group has shown that the collagen IV-derived peptide primarily binds β1 integrins, while the receptor for the somatotropin-derived peptide remains unknown. We investigate these peptides’ mechanisms of action and find both peptides affect the vascular endothelial growth factor (VEGF) pathway as well as focal adhesion kinase (FAK) by changes in phosphorylation level and total protein content. Blocking of FAK both through binding of β1 integrins and through inhibition of VEGFR2 accounts for the synergy we observe. Since resistance through activation of multiple signaling pathways is a central problem of anti-angiogenic therapies in diseases such as cancer, we suggest that peptide combinations such as these are an approach that should be considered as a means to sustain anti-angiogenic and anti-lymphangiogenic therapy and improve efficacy of treatment.
Poly(β-amino ester)-nanoparticle mediated transfection of retinal pigment epithelial cells in vitro and in vivo.
A variety of genetic diseases in the retina, including retinitis pigmentosa and leber congenital amaurosis, might be excellent targets for gene delivery as treatment. A major challenge in non-viral gene delivery remains finding a safe and effective delivery system. Poly(beta-amino ester)s (PBAEs) have shown great potential as gene delivery reagents because they are easily synthesized and they transfect a wide variety of cell types with high efficacy in vitro. We synthesized a combinatorial library of PBAEs and evaluated them for transfection efficacy and toxicity in retinal pigment epithelial (ARPE-19) cells to identify lead polymer structures and transfection formulations. Our optimal polymer (B5-S5-E7 at 60 w/w polymer:DNA ratio) transfected ARPE-19 cells with 44±5% transfection efficacy, significantly higher than with optimized formulations of leading commercially available reagents Lipofectamine 2000 (26±7%) and X-tremeGENE HP DNA (22±6%); (p<0.001 for both). Ten formulations exceeded 30% transfection efficacy. This high non-viral efficacy was achieved with comparable cytotoxicity (23±6%) to controls; optimized formulations of Lipofectamine 2000 and X-tremeGENE HP DNA showed 15±3% and 32±9% toxicity respectively (p>0.05 for both). Our optimal polymer was also significantly better than a gold standard polymeric transfection reagent, branched 25 kDa polyethyleneimine (PEI), which achieved only 8±1% transfection efficacy with 25±6% cytotoxicity. Subretinal injections using lyophilized GFP-PBAE nanoparticles resulted in 1.1±1×10(3)-fold and 1.5±0.7×10(3)-fold increased GFP expression in the retinal pigment epithelium (RPE)/choroid and neural retina respectively, compared to injection of DNA alone (p = 0.003 for RPE/choroid, p<0.001 for neural retina). The successful transfection of the RPE in vivo suggests that these nanoparticles could be used to study a number of genetic diseases in the laboratory with the potential to treat debilitating eye diseases.
Structure-activity relationship (SAR) studies are essential in the generation of peptides with enhanced activity and efficacy as therapeutic agents. In this study, we report a Structure-activity relationship study for a family of mimetic peptides derived from type IV collagen with potent anti-angiogenic properties. The Structure-activity relationship study was conducted using a number of validated in vitro assays including cell proliferation, adhesion, migration, and tubule formation. We report a critical sequence (NINNV) within this peptide series, which is required for the potent anti-angiogenic activity. Detailed amino acid substitutions resulted in peptides with superior efficacy. Specifically, substitutions with isoleucine at positions 12 and 18 along with the substitution of the methionine at position 10 with the non-natural amino acid D-alanine led to an increase in potency by two orders of magnitude over the parent peptide. Several mimetic peptides in this series exhibit a significant improvement of activity over the parent peptide. This improved in vitro activity is expected to correlate with an increase in in vivo activity leading to effective peptides for anti-angiogenic therapy for different disease applications including cancer and age-related macular degeneration.
Transl Oncol. 2012 Apr;5(2):92-7.
Angiogenesis is the formation of neovasculature from preexisting microvessels. Several endogenous proteins regulate the balance of vessel formation and regression in the body including pigment epithelium-derived factor (PEDF), which has been shown to be antiangiogenic and to suppress tumor growth. Using sequence homology and bioinformatics, we previously identified several peptide sequences homologous to an active region of PEDF existing in multiple proteins in the human proteome. These short 11-mer peptides are found in a DEAH box helicase protein, CKIP-1 and caspase 10, and show similar activity in altering endothelial cell adhesion, migration and inducing apoptosis.We tested the peptide derived from DEAH box helicase protein in a triple-negative MDA-MB-231 breast orthotopic xenograft model in severe combined immunodeficient mice and show significant tumor suppression.
Collagen IV and CXC chemokine-derived antiangiogenic peptides suppress glioma xenograft growth. Rosca EV, Lal B, Koskimaki JE, Popel AS, Laterra J. Anticancer Drugs. 2012 Aug;23(7):706-12. doi: 10.1097/CAD.0b013e3283531041.
Endothelial cell dysfunction is a critical component of ocular diseases such as age-related macular degeneration and diabetic retinopathy. An important limitation in endothelial cell research is the difficulty in achieving efficient transfection of these cells. A new polymer library was here synthesized and utilized to find polymeric nanoparticles that can transfect macrovascular (human umbilical vein, HUVECs) and microvascular (human retinal, HRECs) endothelial cells. Nanoparticles were synthesized that can achieve transfection efficiency of up to 85% for HRECs and 65% for HUVECs. These nanoparticle systems enable high levels of expression while avoiding problems associated with viral gene delivery. The polymeric nanoparticles also show cell-specific behavior, with a high correlation between microvascular and macrovascular transfection (R(2) = 0.81) but low correlation between retinal endothelial and retinal epithelial transfection (R(2) = 0.21). These polymeric nanoparticles can be used in vitro as experimental tools and potentially in vivo to target and treat vascular-specific diseases.
Development of a biomimetic peptide derived from collagen IV with anti-angiogenic activity in breast cancer
Cancer Biol Ther. 2011 Nov 1;12(9):808-17. doi: 10.4161/cbt.12.9.17677.
Small peptides derived from somatotropin domain-containing proteins inhibit blood and lymphatic endothelial cell proliferation, migration, adhesion and tube formation. Lee E, Rosca EV, Pandey NB, Popel AS. Int J Biochem Cell Biol. 2011 Dec;43(12):1812-21. doi: 10.1016/j.biocel.2011.08.020. Epub 2011 Sep 6.
Breast cancer is one of the most commonly diagnosed malignancies in women. Despite the remarkable success of mammography screening and use of adjuvant systemic therapy, it is estimated that approximately 200,000 new diagnoses will be made this year and 40,000 deaths will occur due to this disease (American Cancer Society). Angiogenesis, the growth of vessels from pre-existing microvasculature, is an essential component of tumor progression and has emerged as a therapeutic modality for anti-angiogenic therapies in cancer. Here we report in vitro and in vivo findings with a 20 amino acid peptide belonging to the collagen IV family, modified to facilitate possible translation to clinical applications. The two cysteines in its natural peptide progenitor were replaced by L-α-amino-n-butyric acid, a non-natural amino acid. The modified peptide was tested in vitro using endothelial cells and in vivo using mouse orthotopic breast cancer xenograft model with MDA-MB-231 human breast cancer cells. This modified peptide demonstrated no significant changes in activity from the parent peptide; however, because it lacks cysteines, it is more suitable for clinical translation. We also investigated its efficacy in combination with a commonly used chemotherapeutic agent paclitaxel; the inhibition of tumor growth by the peptide was similar to that of paclitaxel alone, but the combination did not exhibit any additional inhibition. We have performed further characterization of the mechanism of action (MOA) for this peptide to identify its target receptors, enhancing its translation potential as an anti-angiogenic, non-vascular endothelial growth factor (VEGF) targeting agent for therapy in breast cancer.
Anti-angiogenic peptides for cancer therapeutics. Rosca EV, Koskimaki JE, Rivera CG, Pandey NB, Tamiz AP, Popel AS. Curr Pharm Biotechnol. 2011 Aug;12(8):1101-16.
Novel peptide-specific quantitative structure-activity relationship (QSAR) analysis applied to collagen IV peptides with antiangiogenic activity. Rivera CG, Rosca EV, Pandey NB, Koskimaki JE, Bader JS, Popel AS. J Med Chem. 2011 Oct 3;54(19):6492-500. doi: 10.1021/jm200114f. Epub 2011 Sep 13.
Pentastatin-1, a collagen IV derived 20-mer peptide, suppresses tumor growth in a small cell lung cancer xenograft model. Koskimaki JE, Karagiannis ED, Tang BC, Hammers H, Watkins DN, Pili R, Popel AS. BMC Cancer. 2010 Feb 1;10:29. doi: 10.1186/1471-2407-10-29.
Angiogenesis is essential to human biology and of great clinical significance. Excessive or reduced angiogenesis can result in, or exacerbate, several disease states, including tumor formation, exudative age-related macular degeneration (AMD) and ischemia. Innovative drug delivery systems can increase the effectiveness of therapies used to treat angiogenesis-related diseases.
This paper reviews the basic biology of angiogenesis, including current knowledge about its disruption in diseases, with the focus on cancer and AMD. Anti- and proangiogenic drugs available for clinical use or in development are also discussed, as well as experimental drug delivery systems that can potentially improve these therapies to enhance or reduce angiogenesis in a more controlled manner.
Laboratory and clinical results have shown pro- or antiangiogenic drug delivery strategies to be effective in drastically slowing disease progression. Further research in this area will increase the efficacy, specificity and duration of these therapies. Future directions with composite drug delivery systems may make possible targeting of multiple factors for synergistic effects.
Peptides derived from type IV collagen, CXC chemokines, and thrombospondin-1 domain-containing proteins inhibit neovascularization and suppress tumor growth in MDA-MB-231 breast cancer xenografts.
Angiogenesis or neovascularization, the process of new blood vessel formation from preexisting microvasculature, involves interactions among several cell types including parenchymal, endothelial cells, and immune cells. The formation of new vessels is tightly regulated by a balance between endogenous proangiogenic and antiangiogenic factors to maintain homeostasis in tissue; tumor progression and metastasis in breast cancer have been shown to be angiogenesis-dependent. We previously introduced a systematic methodology to identify putative endogenous antiangiogenic peptides and validated these predictions in vitro in human umbilical vein endothelial cell proliferation and migration assays. These peptides are derived from several protein families including type IV collagen, CXC chemokines, and thrombospondin-1 domain-containing proteins. On the basis of the results from the in vitro screening, we have evaluated the ability of one peptide selected from each family named pentastatin-1, chemokinostatin-1, and properdistatin, respectively, to suppress angiogenesis in an MDA-MB-231 human breast cancer orthotopic xenograft model in severe combined immunodeficient mice. Peptides were administered intraperitoneally once per day. We have demonstrated significant suppression of tumor growth in vivo and subsequent reductions in microvascular density, indicating the potential of these peptides as therapeutic agents for breast cancer.
A peptide derived from type 1 thrombospondin repeat-containing protein WISP-1 inhibits corneal and choroidal neovascularization
Ocular neovascularization is the primary cause of blindness in a wide range of prevalent ocular diseases including proliferative diabetic retinopathy, exudative age-related macular degeneration, and retinopathy of prematurity, among others. Antiangiogenic therapies are starting to give promising results in these diseases. In the present study the antiangiogenic potential of an 18-mer peptide derived from type 1 thrombospondin repeat-containing protein WISP-1 (wispostatin-1) was analyzed in vitro with human retinal endothelial cell proliferation and migration assays. The peptide was also tested in vivo in the corneal micropocket and the laser-induced choroidal neovascularization (CNV) mouse models.
Human retinal endothelial cells were treated with the WISP-1 peptide and in vitro migration and proliferation assays were performed. Also evaluated was the antiangiogenic effect of this peptide in vivo using the corneal micropocket assay and the laser-induced CNV model.
Wispostatin-1 derived peptide demonstrated antimigratory and antiproliferative activity in vitro. Wispostatin-1 completely abolished bFGF-induced neovascularization in the corneal micropocket assay. The peptide also demonstrated significant inhibition of laser-induce=”text-align: justify;”>An inhibitory effect of Wispostatin-1 on ocular neovascularization was found in vitro and in vivo. The identification of novel and potent endogenous peptide inhibitors provides insight into the pathogenesis of corneal and choroidal neovascularization. The results demonstrate potential for therapeutic application in prevalent ocular disease.
A systematic methodology for proteome-wide identification of peptides inhibiting the proliferation and migration of endothelial cells
We introduce a systematic computational methodology based on bioinformatics that has enabled us to identify and classify >120 endogenous peptide inhibitors of endothelial cell proliferation and migration. These peptides are derived from members of the type IV collagen, thrombospondin, and CXC chemokine protein families, as well as somatotropin hormones, serpins, and various kringle-containing proteins. Their activity in suppressing the proliferation and migration of endothelial cells in vitro provides proof of principle for the validity of this computational method. Interestingly, some of the peptides are derived from proteins known to be proangiogenic. By performing receptor neutralization studies, we have identified receptors to which these peptides bind. On the basis of this receptor-binding information, we evaluated several examples of peptide-based combinatorial screening strategies. In some cases, this combinatorial screening identified strong synergism between peptides. The current work provides a guideline for a computational-based peptidomics approach for the discovery of endogenous bioactive peptides.