Site-specific modification of anti-angiogenesis peptide HM-3 by polyethylene glycol molecular weight of 20 kDa

Albumin Fusion at the N-Terminus or C-Terminus of HM-3 Leads to Improved Pharmacokinetics and Bioactivities

HM-3, an integrin antagonist, exhibits anti-tumor biological responses and therefore has potential as a therapeutic polypeptide. However, the clinical applications of HM-3 are limited by its short half-life. In this study, we genetically fused human serum albumin (HSA) to the N or C-terminus of HM-3 to improve HM-3 pharmacokinetics. HM-3/HSA proteins were successfully expressed in Pichia pastoris and displayed improved pharmacokinetic properties and stability. Among them, the half-life of HM-3-HSA was longer than HSA-HM-3. In vitro, the IC₅₀ values of HSA-HM-3 and HM-3-HSA were 0.38 ± 0.14 μM and 0.25 ± 0.08 μM in B16F10 cells, respectively. In vivo, the inhibition rates of B16F10 tumor growth were 36% (HSA-HM-3) and 56% (HM-3-HSA), respectively, indicating antitumor activity of HM-3-HSA was higher than HSA-HM-3. In conclusion, these results suggested that the HM-3/HSA fusion protein might be potential candidate HM-3 agent for treatment of melanoma and when HSA was fused at the C-terminus of HM-3, the fusion protein had a higher stability and activity.

Combined administration of PTX and S-HM-3 in TPGS/Solutol micelle system for oncotarget therapy

Background

S-HM-3 is a tumor angiogenesis inhibitor with short half-life (25 min). In this present, TPGS/Solutol polymeric micelles was prepared to load together insoluble paclitaxel (PTX) and soluble S-HM-3, expecting to together deliver them to the tumor site with long-circulating, targeting function and combating multi-drug resistance (MDR).

Materials and methods

PTX and S-HM-3 loaded TPGS/Solutol micelles (PHTSm) were prepared by the method of thin-film evaporation, and characterized by dynamic light scattering, transmission electron microscope (TEM), atomic force microscopy (AFM) and releasing properties. The anticancer effect of the polymeric micelles system was evaluated and confirmed by experiments of in vitro cell uptake study, in vivo pharmacokinetics, and pharmacodynamics studies.

Results

Micelles exhibited smooth spherical morphology with 20~30 nm and low critical micelle concentration (CMC) value of 0.000124 mg/mL. Only about 30% of PTX were slowly released from micelles at 48h, which can beneficial to the long circulation in blood. The results of in vitro cell assay proved that S-HM-3 could be easier to get into MDA-MB-231 cell, and its angiogenesis inhibition ability was also enhanced after integrating into micelles. In particular, the results of in vivo studies showed that the half-life of S-HM-3 and PTX was significantly prolonged 25.27 and 5.54 folds, and their AUC_0-∞ was enhanced 129.78 and 15.65 times, respectively. Meanwhile 83.05% tumor inhibition rate of PHTSm was achieved compared with 59.99% of PTX.

Conclusions

TPGS and Solutol micelles hold promising potential to resolve the conundrum of combined therapy of cytotoxic drug and angiogenesis inhibitor with different physicochemical property and anticancer mechanism in clinical use.

The Protective Effect of a Long-Acting and Multi-Target HM-3-Fc Fusion Protein in Rheumatoid Arthritis

Current treatment of rheumatoid arthritis (RA) is limited by relative shortage of treatment targets. HM-3 is a novel anti-RA polypeptide consisting of 18 amino acids with integrin αVβ3 and α5β1 as targets. Previous studies confirmed that HM-3 effectively inhibited the synovial angiogenesis and the inflammatory response. However, due to its short half-life, the anti-RA activity was achieved by frequent administration. To extend the half-life of HM-3, we designed a fusion protein with name HM-3-Fc, by combination of modified Fc segment of immunoglobulin 4 (IgG4) with HM-3 polypeptide. In vitro cell experiments demonstrated that HM-3-Fc inhibited the proliferation of splenic lymphocytes and reduced the release of TNF-α from macrophages. The pharmacodynamics studies on mice paw in Collagen-Induced Arthritis (CIA) model demonstrated that HM-3-Fc administered once in 5 days in the 50 and 25 mg/kg groups, or once in 7 days in the 25 mg/kg group showed a better protective effect within two weeks than the positive control adalimumab and HM-3 group. Preliminary pharmacokinetic studies in cynomolgus confirmed that the in vivo half-life of HM-3-Fc was 15.24 h in comparison with 1.32 min that of HM-3, which demonstrated that an Fc fusion can effectively increase the half-life of HM-3 and make it possible for further reduction of subcutaneous injection frequency. Fc-HM-3 is a long-acting active molecule for RA treatment.

In vitro and in vivo activities of an antitumor peptide HM-3: A special dose-efficacy relationship on an HCT‑116 xenograft model in nude mice

Anti-angiogenesis is an important therapy for cancer treatment. Peptide HM-3 is an integrin antagonist with anti-angiogenic and antitumor activity. Previous research found that HM-3 at an effective dose inhibited tumor growth whereas at higher doses, the inhibitory effect gradually decreased. In the present study, three human tumor cell lines, human colorectal cancer cell (HCT-116) and human hepatic cancer cell (Hep G-2 and SMMC-7721), were selected and their interactions with HM-3 were compared with western blot and flow cytometric assays. The effect of HM-3 on the migration of two tumor cell lines (HCT-116 and Hep G-2) was also evaluated and a bell-shaped dose-efficacy curve was found for both cell lines. Furthermore, in vivo imaging in BALB/c nude mice confirmed that HM-3 had a short half-life and targeted the tumor tissue. Moreover, on an HCT-116 xenograft model in BALB/c nude mice, HM-3 at 3 mg/kg inhibited tumor growth with an inhibition rate of 71.5% (by tumor mass) whereas at 12 and 48 mg/kg, the inhibition rates were 59.2 and 36.0%, respectively. Immunohistochemistry analyses found that both sunitinib (60 mg/kg) and HM-3 (3 and 48 mg/kg) decreased microvascular density and increased percent of HIF-1α and VEGF expressing cells. The present study investigated the effect of tumor microenvironments on the antitumor effect of HM-3 and concluded that HM-3 inhibited angiogenesis and thereafter tumor growth by directly inhibiting HUVEC migration. The special dose-efficacy curves for antitumor effect and for cell migration inhibition were correlated. The present study also confirmed that the effective dose has to be strictly defined for better clinical applications of anti‑angiogenic drugs such as HM-3.

An integrin αvβ3 antagonistic modified peptide inhibits tumor growth through inhibition of the ERK and AKT signaling pathways

HM-3, an RGD (Arg-Gly-Asp)-modified antitumor polypeptide designed independently, has been demonstrated for its robust inhibitory effects on tumors. However, the intravenous administration and short half-life in vivo are inconvenient to its clinical application. To solve these issues, PEGylated HM-3 (mPEG-SC20k-HM-3) with prolonged half‑time in vivo and subcutaneous administration was obtained after repeated screening of different types of PEG and numerous efficacy assays. The present study aimed to evaluate the antitumor activity and investigate the mechanism of the modified peptide to interpret the antitumor properties of mPEG-SC20k-HM-3 comprehensively and clearly. The results of the antitumor activity assays in vitro indicated that mPEG-SC20k-HM-3 exhibited a marked inhibitory activity on tumor metastasis and angiogenesis. mPEG-SC20k-HM-3 (73.4 mg/kg, sc) achieved a tumor inhibitory rate of 70.1% in an H460 (human non-small cell lung cancer) xenograft model with scarce cytotoxicity, compared with a rate of 72.2% for Avastin (10.0 mg/kg, iv). The mechanistic study showed that mPEG-SC20k-HM-3 could target integrin αvβ3 to block the downstream ERK and Akt pathways, as the expression levels of VEGF, Akt1, p-Akt1, ERK1/2, p-ERK1/2, MEK1, p-MEK1, integrin αv and β3 were reduced after HUVECs were incubated with mPEG-SC20k-HM-3 for 24 h. In conclusion, the antitumor activity of mPEG-SC20k-HM-3 in vitro and in vivo is promising and the mechanism was clearly reflected in the present study.

Augmented anti-angiogenesis activity of polysulfated heparin-endostatin and polyethylene glycol-endostatin in alkali burn-induced corneal ulcers in rabbits

Endostatin (ES) is an endogenous angiogenesis inhibitor that has the ability to inhibit tumor growth and metastasis. However, its clinical application is limited by a number of disadvantages, such as poor stability, short half-life and the requirement of high doses to maintain its efficacy. The chemical modification on ES may offer a solution to these disadvantages. The aim of the present study was to evaluate the effects of ES, polysulfated heparin-endostatin (PSH-ES) and polyethylene glycol-endostatin (PEG-ES) on the endothelial cell proliferation and angiogenesis associated with corneal neovascularization (CNV) and to determine their mechanisms of action. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) was used to study the effects of ES and its derivatives on endothelial cell proliferation in vitro, and rabbits were used to evaluate the effects of ES and its derivatives on CNV in vivo. In the evaluation of CNV, the expression of vascular endothelial growth factor in the cornea was measured via immunohistochemistry and microvessels were counted. ES and its derivatives significantly inhibited endothelial cell proliferation in vitro (P<0.05) and suppressed CNV in vivo. Among the compounds examined, ES most effectively inhibited endothelial cell proliferation in vitro (P<0.05); however, PSH-ES and PEG-ES most effectively inhibited CNV in vivo (P<0.05). These results indicate that PSH-ES and PEG-ES are candidate anti-angiogenesis drugs.

Inhibitory effect of polysulfated heparin endostatin on alkali burn induced corneal neovascularization in rabbits

AIM

To investigate anti-angiogenic effects of polysulfated heparin endostatin (PSH-ES) on alkali burn induced corneal neovascularization (NV) in rabbits.

METHODS

An alkali burn was made on rabbit corneas to induce corneal NV in the right eye of 24 rabbits. One day after burn creation, a 0.2 mL subconjunctival injection of 50 µg/mL PSH-ES, 50 µg/mL recombinant endostatin (ES), or normal saline was administered every other day for a total of 14d (7 injections). Histology and immunohistochemisty were used to examine corneas. Corneal NV growth was evaluated as microvessel quantity and corneal vascular endothelial growth factor (VEGF) expression was measured by immunohistochemical assay.

RESULTS

Subconjunctival injection of ES and PSH-ES resulted in significant corneal NV suppression, but PSH-ES had a more powerful anti-angiogenic effect than ES. Mean VEGF concentration in PSH-ES treated corneas was significantly lower than in ES treated and saline treated corneas. Histological examination showed that corneas treated with either PSH-ES or ES had significantly fewer microvessels than eyes treated with saline. Additionally corneas treated with PSH-ES had significantly fewer microvessels than corneas treated with ES.

CONCLUSION

Both PSH-ES and recombinant ES effectively inhibit corneal NV induced by alkali burn. However, PSH-ES is a more powerful anti-angiogenic agent than ES. This research has the potential to provide a new treatment option for preventing and treating corneal NV.

Inhibition of neutrophil collagenase/MMP-8 and gelatinase B/MMP-9 and protection against endotoxin shock

Endotoxin shock is a life-threatening disorder, associated with the rapid release of neutrophil enzymes, including neutrophil collagenase/matrix metalloproteinase-8 (MMP-8) and gelatinase B/matrix metalloproteinase-9 (MMP-9). After activation, these enzymes cleave extracellular matrix components and cytokines and thus may contribute to shock syndrome development. MMP inhibitors have been suggested as immunotherapy of endotoxin shock. However, little is known about the therapeutic time window of MMP inhibition. Here, a sublethal endotoxin shock mouse model was used to evaluate the effect of an MMP inhibiting peptide (P2) after intravenous or intraperitoneal injection and to study the time window between LPS and inhibitor injections. With the use of a specific ELISA the plasma P2 concentrations were monitored. Whereas we corroborated the treatment strategy of MMP targeting in endotoxin shock with a new inhibitor, we also demonstrated that the time window, within which effective MMP inhibition increased the survival rates, is rather limited.

Pharmacokinetics of HM-3 after intravitreal administration in mice

PURPOSE

HM-3, an RGD-modified endostatin-derived polypeptide, is a potent angiogenesis inhibitor synthesized in our laboratory. This study investigated the HM-3 pharmacokinetics of intravitreally administered in mice eyes as an anti-angiogenesis drug for age-related macular degeneration.

MATERIALS AND METHODS

A total of 288 C57BL/6J mice were evaluated and divided into four groups. Each mouse in different groups received single bilateral intravitreal injection with HM-3. The concentrations of HM-3 in choroid/sclera, retina and serum were determined by indirect competitive enzyme-linked immunosorbent assay.

RESULTS

After intravitreal administration of doses of 0, 10, 20 and 40 μg/eye HM-3, the observed maximum concentration (Cmax) was 12.98 ± 1.42, 27.87 ± 3.64 and 55.96 ± 11.94 ng/mg, respectively; and the total area under the curve (AUCtot) was 739.23 ± 190.32, 1171.74 ± 528.75 and 1777.71 ± 511.64 h ng/mg; the elimination half-life (T1/2) in retina was 104.85 ± 36.90, 107.42 ± 35.25 and 101.12 ± 15.82 h; the mean residence time (MRT) was 172.46 ± 63.80, 164.70 ± 52.72 and 181.32 ± 26.01 h, respectively. In choroid/sclera, the Cmax was 5.29 ± 0.34, 6.29 ± 1.87 and 8.14 ± 0.71 ng/mg, respectively; AUCtot was 579.03 ± 56.50, 762.20 ± 201.09 and 720.91 ±243.87 h ng/mg; T1/2 was 54.04 ± 25.99, 59.33 ± 24.46 and 47.10 ± 10.00 h, respectively; MRT was 139.98 ± 23.93, 155.43 ± 17.81 and 136.45 ± 18.17 h, respectively. But in serum, the Cmax was 482.00 ± 38.97, 493.94 ± 97.64 and 1033.10 ± 276.33 ng/ml, respectively; AUCtot was 21128.55 ± 4683.68, 53444.57 ± 16963.99 and 53164.84 ±1535.06 h ng/ml; T1/2 was 48.39 ± 14.89, 47.96 ± 12.97 and 49.98 ± 30.07 h, respectively; MRT was 108.6 ± 47.17, 159.76 ± 18.82 and 125.33 ± 21.41 h, respectively.

CONCLUSIONS

The pharmacokinetic profiles of intravitreal administration HM-3 provide the basis for the development of reasonable dosing regimens of clinical choroidal neovascularization (CNV) treatment. However, the vitreous and blood retinal barrier might be barriers to drug distribution and diffusion. In addition, fluid flow for the anterior transport and choroidal blood circulation might play important roles for multiple peaking. Carrying out the research into pharmacokinetics of HM-3 provides the information for laying down drug delivery scheme in mice model of CNV.

Trans-3,4,5,4'-tetramethoxystilbene, a resveratrol analog, potently inhibits angiogenesis in vitro and in vivo

Aim:

Trans-3,4,5,4′-tetramethoxystilbene (DMU-212) has shown strong antiproliferative activities against a variety of cancer cells. The aim of this study was to investigate the anti-angiogenic effects of DMU-212 in vitro and in vivo.

Methods:

Human umbilical vein endothelial cells (HUVECs) were used in this study. Cell viability was studied with MTT assay, and cell apoptosis was evaluated using TUNEL assay and morphological observation. The expression of the related genes and proteins was analyzed with qRT-PCR and Western blot, respectively. Angiogenesis of HUVECs were studied using cell migration and capillary-like tube formation assays in vitro, and mouse Matrigel plug assay and chick chorioallantoic membrane (CAM) assay in vivo. The tyrosine kinase activities of VEGFR1 and VEGFR2 were measured using commercial kits.

Results:

DMU-212 (5–80 μmol/L) significantly inhibited VEGF-stimulated proliferation of HUVECs (IC₅₀ value was approximately 20 μmol/L), and induced apoptosis. Furthermore, DMU-212 concentration-dependently inhibited VEGF-induced migration of HUVECs and capillary-like structure formation in vitro. DMU-212 also inhibited VEGF-induced generation of new vasculature in Matrigel plugs in vivo with significantly decreased area of infiltrating CD31-positive endothelial cells, and inhibited newly formed microvessels in chick CAMs. Moreover, DMU-212 concentration-dependently suppressed VEGF-induced phosphorylation of VEGFR2, and inhibited phosphorylation of multiple downstream signaling components in the VEGFR2 pathway, including c-Src, FAK, Erk1/2, Akt, mTOR, and p70S6K in HUVECs. DMU-212 had no effect on VEGF-induced phosphorylation of VEGFR1.

Conclusion:

DMU-212 is a potent inhibitor of angiogenesis that exerts anti-angiogenic activity at least in part through the VEGFR2 signaling pathway.

Peptides for cancer therapy: a drug-development opportunity and a drug-delivery challenge

Therapeutic peptides (TPs) are a class of peptide-based agents capable of eliciting a therapeutic response by modulation of targets within or on the surface of cells. TPs are advantageous because they are amenable to rational design, they have high specificity for their targets and can be made to target almost any protein of interest, including proteins for which we have no small-molecule drugs. Owing to this versatility, TPs have a great potential for cancer therapy in an age of personalized medicine, in which we need novel drugs to target the many novel pathways being discovered as tumor drivers. However, in order to utilize TPs as drugs, many obstacles must be overcome. TPs have short half-lives in systemic circulation, are easily degraded by proteases in plasma and target cells, are often cleared by the reticuloendothelial system and can be immunogenic. This article will discuss ways of overcoming many of these hurdles by utilizing macromolecular peptide delivery systems and tumor-targeting agents.

In vivo anti-tumor activity of polypeptide HM-3 modified by different polyethylene glycols (PEG)

HM-3, designed by our laboratory, is a polypeptide composed of 18 amino acids. Pharmacodynamic studies in vivo and in vitro indicated that HM-3 could inhibit endothelial cell migration and angiogenesis, thereby inhibiting tumor growth. However, the half-life of HM-3 is short. In this study, we modified HM-3 with different polyethylene glycols (PEG) in order to reduce the plasma clearance rate, extend the half-life in the body, maintain a high concentration of HM-3 in the blood and increase the therapeutic efficiency. HM-3 was modified with four different types of PEG with different molecular weights (ALD-mPEG_5k, ALD-mPEG_10k, SC-mPEG_10k and SC-mPEG_20k), resulting in four modified products (ALD-mPEG_5k-HM-3, ALD-mPEG_10k-HM-3, SC-mPEG_10k-HM-3 and SC-mPEG_20k-HM-3, respectively). Anti-tumor activity of these four modified HM-3 was determined in BALB/c mice with Taxol as a positive control and normal saline as a negative control. Tumor weight inhibition rates of mice treated with Taxol, HM-3, ALD-mPEG_5k-HM-3, ALD-mPEG_10k-HM-3, SC-mPEG_10k-HM-3 and SC-mPEG_20k-HM-3 were 44.50%, 43.92%, 37.95%, 31.64%, 20.27% and 50.23%, respectively. Tumor inhibition rates in the Taxol, HM-3 and SC-mPEG_20k-HM-3 groups were significantly higher than that in the negative control group. The efficiency of tumor inhibition in the SC-mPEG_20k-HM-3 group (drug treatment frequency: once per two days) was better than that in the HM-3 group (drug treatment frequency: twice per day). In addition, tumor inhibition rate in the SC-mPEG_20k-HM-3 group was higher than that in the taxol group. We conclude that SC-mPEG_20k-HM-3 had a low plasma clearance rate and long half-life, resulting in high anti-tumor therapeutic efficacy in vivo. Therefore, SC-mPEG_20k-HM-3 could be potentially developed as new anti-tumor drugs.