Molecular basis for the targeted binding of RGD-containing peptide to integrin αVβ3

Enzyme-Instructed Photoactivatable Supramolecular Antigens on Cancer Cell Membranes for Precision-Controlled T-Cell-Based Cancer Immunotherapy

Cancer immunotherapies based on cytotoxic CD8+ T lymphocytes (CTLs) are highly promising for cancer treatment. The specific interaction between T-cell receptors and peptide-MHC-I complexes (pMHC-I) on cancer cell membranes critically determines their therapeutic outcomes. However, the lack of appropriate endogenous antigens for MHC-I presentation disables tumor recognition by CTLs. By devising three antigen-loaded self-assembling peptides of pY-K(Ag)-ERGD, pY-K(Ag)-E, and Y-K(Ag)-ERGD to noncovalently generate light-activatable supramolecular antigens at tumor sites in different manners, we report pY-K(Ag)-ERGD as a promising candidate to endow tumor cells with pMHC-I targets on demand. Specifically, pY-K(Ag)-ERGD first generates low-antigenic supramolecular antigens on cancer cell membranes, and a successive light pulse allows antigen payloads to efficiently release from the supramolecular scaffold, directly producing antigenic pMHC-I. Intravenous administration of pY-K(Ag)-ERGD enables light-controlled tumor inhibition when combined with adoptively transferred antigen-specific CTLs. Our strategy is feasible for broadening tumor antigen repertoires for T-cell immunotherapies and advancing precision-controlled T-cell immunotherapies.

Self-Assembly of Peptides as an Alluring Approach toward Cancer Treatment and Imaging

Cancer is a severe threat to humans, as it is the second leading cause of death after cardiovascular diseases and still poses the biggest challenge in the world of medicine. Due to its higher mortality rates and resistance, it requires a more focused and productive approach to provide the solution for it. Many therapies promising to deliver favorable results, such as chemotherapy and radiotherapy, have come up with more negatives than positives. Therefore, a new class of medicinal solutions and a more targeted approach is of the essence. This review highlights the alluring properties, configurations, and self-assembly of peptide molecules which benefit the traditional approach toward cancer therapy while sparing the healthy cells in the process. As targeted drug delivery systems, self-assembled peptides offer a wide spectrum of conjugation, biocompatibility, degradability-controlled responsiveness, and biomedical applications, including cancer treatment and cancer imaging.

Integrated Computational Pipeline for the High-Throughput Discovery of Cell Adhesion Peptides

Cell adhesion peptides (CAPs) often play a critical role in tissue engineering research. However, the discovery of novel CAPs for diverse applications remains a challenging and time-intensive process. This study presents an efficient computational pipeline integrating sequence embeddings, binding predictors, and molecular dynamics simulations to expedite the discovery of new CAPs. A Pro2vec model, trained on vast CAP data sets, was built to identify RGD-similar tripeptide candidates. These candidates were further evaluated for their binding affinity with integrin receptors using the Mutabind2 machine learning model. Additionally, molecular dynamics simulations were applied to model receptor-peptide interactions and calculate their binding free energies, providing a quantitative assessment of the binding strength for further screening. The resulting peptide demonstrated performance comparable to that of RGD in endothelial cell adhesion and spreading experimental assays, validating the efficacy of the integrated computational pipeline.

Emerging non-antibody‒drug conjugates (non-ADCs) therapeutics of toxins for cancer treatment

The non-selective cytotoxicity of toxins limits the clinical relevance of the toxins. In recent years, toxins have been widely used as warheads for antibody‒drug conjugates (ADCs) due to their efficient killing activity against various cancer cells. Although ADCs confer certain targeting properties to the toxins, low drug loading capacity, possible immunogenicity, and other drawbacks also limit the potential application of ADCs. Recently, non-ADC delivery strategies for toxins have been extensively investigated. To further understand the application of toxins in anti-tumor, this paper provided an overview of prodrugs, nanodrug delivery systems, and biomimetic drug delivery systems. In addition, toxins and their combination strategies with other therapies were discussed. Finally, the prospect and challenge of toxins in cancer treatment were also summarized.

A Cathepsin B-Sensitive Gemcitabine Prodrug for Enhanced Pancreatic Cancer Therapy

Although gemcitabine (GEM) is a first-line chemotherapeutic drug in treating pancreatic cancer, the therapeutic efficacy of GEM is relatively poor. One main reason is that GEM can be easily deaminated to inactive 2',2'-difluorodeoxyuridine (dFdU) by cytidine deaminase (CDA). In order to improve the antitumor activity of GEM, a polypeptide modified GEM prodrug RGDGFLG-GEM (GEM-RGD) is designed. Because the amino group of GEM is protected by RGDGFLG peptide sequence, the in vivo stability of GEM-RGD can be significantly improved since the deamination of GEM can be avoided. GEM-RGD shows enhanced uptake by pancreatic cancer cells due to the active targeting RGD group. The cathepsin B-sensitive GFLG sequence endows GEM-RGD with specific release of GEM in pancreatic cancer cells. Compared to free GEM and non-targeted GEM prodrug RDGGFLG-GEM (GEM-RDG), GEM-RGD exhibits enhanced antitumor activity and reduced systemic toxicity. These results implies that GEM-RGD is a promising candidate in treating pancreatic cancer.

Mechanism of RGD-conjugated nanodevice binding to its target protein integrin αVβ3 by atomistic molecular dynamics and machine learning

Active targeting strategies have been proposed to enhance the selective uptake of nanoparticles (NPs) by diseased cells, and recent experimental findings have proven the effectiveness of this approach. However, no mechanistic studies have yet revealed the atomistic details of the interactions between ligand-activated NPs and integrins. As a case study, here we investigate, by means of advanced molecular dynamics simulations (MD) and machine learning methods (namely equilibrium MD, binding free energy calculations and training of self-organized maps), the interaction of a cyclic-RGD-conjugated PEGylated TiO2 NP (the nanodevice) with the extracellular segment of integrin αVβ3 (the target), the latter experimentally well-known to be over-expressed in several solid tumors. Firstly, we proved that the cyclic-RGD ligand binding to the integrin pocket is established and kept stable even in the presence of the cumbersome realistic model of the nanodevice. In this respect, the unsupervised machine learning analysis allowed a detailed comparison of the ligand/integrin binding in the presence and in the absence of the nanodevice, which unveiled differences in the chemical features. Then, we discovered that unbound cyclic RGDs conjugated to the NP largely contribute to the interactions between the nanodevice and the integrin. Finally, by increasing the density of cyclic RGDs on the PEGylated TiO2 NP, we observed a proportional enhancement of the nanodevice/target binding. All these findings can be exploited to achieve an improved targeting selectivity and cellular uptake, and thus a more successful clinical outcome.

Lysosome and related protein degradation technologies

Recently, targeted protein degradation technologies based on lysosomal pathways have been developed. Lysosome-based targeted protein degradation technology has a broad range of substrates and the potential to degrade intracellular and extracellular proteins, protein aggregates, damaged organelles and non-protein molecules. Thus, they hold great promise for drug R&D. This study has focused on the biogenesis of lysosomes, their basic functions, lysosome-associated diseases and targeted protein degradation technologies through the lysosomal pathway. In addition, we thoroughly examine the potential applications and limitations of this technology and engage in insightful discussions on potential avenues for future research. Our primary objective is to foster preclinical research on this technology and facilitate its successful clinical implementation.

Engineering nanoparticle toolkits for mRNA delivery

The concept of using mRNA to produce its own medicine in situ in the body makes it an ideal drug candidate, holding great potential to revolutionize the way we approach medicine. The unique characteristics of mRNA, as well as its customizable biomedical functions, call for the rational design of delivery systems to protect and transport mRNA molecules. In this review, a nanoparticle toolkit is presented for the development of mRNA-based therapeutics from a drug delivery perspective. Nano-delivery systems derived from either natural systems or chemical synthesis, in the nature of organic or inorganic materials, are summarised. Delivery strategies in controlling the tissue targeting and mRNA release, as well as the role of nanoparticles in building and boosting the activity of mRNA drugs, have also been introduced. In the end, our insights into the clinical and translational development of mRNA nano-drugs are presented.

Transmorphic phage-guided systemic delivery of TNFα gene for the treatment of human pediatric medulloblastoma

Medulloblastoma is the most common childhood brain tumor with an unfavorable prognosis and limited options of harmful treatments that are associated with devastating long-term side effects. Therefore, the development of safe, noninvasive, and effective therapeutic approaches is required to save the quality of life of young medulloblastoma survivors. We postulated that therapeutic targeting is a solution. Thus, we used a recently designed tumor-targeted bacteriophage (phage)-derived particle, named transmorphic phage/AAV, TPA, to deliver a transgene expressing the tumor necrosis factor-alpha (TNFα) for targeted systemic therapy of medulloblastoma. This vector was engineered to display the double-cyclic RGD4C ligand to selectively target tumors after intravenous administration. Furthermore, the lack of native phage tropism in mammalian cells warrants safe and selective systemic delivery to the tumor microenvironment. In vitro RGD4C.TPA.TNFα treatment of human medulloblastoma cells generated efficient and selective TNFα expression, subsequently triggering cell death. Combination with the chemotherapeutic drug cisplatin used clinically against medulloblastoma resulted in augmented effect through the enhancement of TNFα gene expression. Systemic administration of RGD4C.TPA.TNFα to mice-bearing subcutaneous medulloblastoma xenografts resulted in selective tumor homing of these particles and consequently, targeted tumor expression of TNFα, apoptosis, and destruction of the tumor vasculature. Thus, our RGD4C.TPA.TNFα particle provides selective and efficient systemic delivery of TNFα to medulloblastoma, yielding a potential TNFα anti-medulloblastoma therapy while sparing healthy tissues from the systemic toxicity of this cytokine.

Irisin Protects against Loss of Trabecular Bone Mass and Strength in Adult Ovariectomized Mice by Stimulating Osteoblast Activity

Irisin is a peptide secreted by skeletal muscle that plays a major role in bone metabolism. Experiments in mouse models have shown that administration of recombinant irisin prevents disuse-induced bone loss. In this study, we aimed to evaluate the effects of irisin treatment for the prevention of bone loss in the ovariectomized (Ovx) mouse, the animal model commonly used to investigate osteoporosis caused by estrogen deficiency. Micro-Ct analysis conducted on Sham mice (Sham-veh) and Ovx mice treated with vehicle (Ovx-veh) or recombinant irisin (Ovx-irisn) showed bone volume fraction (BV/TV) decreases in femurs (Ovx-veh 1.39± 0.71 vs. Sham-veh 2.84 ± 1.23; p = 0.02) and tibia at both proximal condyles (Ovx-veh 1.97 ± 0.68 vs. Sham-veh 3.48 ± 1.26; p = 0.03) and the subchondral plate (Ovx-veh 6.33 ± 0.36 vs. Sham-veh 8.18 ± 0.41; p = 0.01), which were prevented by treatment with a weekly dose of irisin for 4 weeks. Moreover, histological analysis of trabecular bone showed that irisin increased the number of active osteoblasts per bone perimeter (Ovx-irisin 32.3 ± 3.9 vs. Ovx-veh 23.5 ± 3.6; p = 0.01), while decreasing osteoclasts (Ovx-irisin 7.6 ± 2.4 vs. Ovx-veh 12.9 ± 3.04; p = 0.05). The possible mechanism by which irisin enhances osteoblast activity in Ovx mice is upregulation of the transcription factor Atf4, one of the key markers of osteoblast differentiation, and osteoprotegerin, thereby inhibiting osteoclast formation.

Highlights on Cell-Penetrating Peptides and Polymer-Lipid Hybrid Nanoparticle: Overview and Therapeutic Applications for Targeted Anticancer Therapy

Polymer-lipid hybrid nanoparticles (PLHNs) have been widely used as a vehicle for carrying anticancer owing to its unique framework of polymer and lipid combining and giving the maximum advantages over the lipid and polymer nanoparticle drug delivery system. Surface modification of PLHNs aids in improved targeting and active delivery of the encapsulated drug. Therefore, surface modification of the PLHNs with the cell-penetrating peptide is explored by many researchers and is explained in this review. Cell-penetrating peptides (CPPs) are made up of few amino acid sequence and act by disrupting the cell membrane and transferring the cargos into the cell. Ideally, we can say that CPPs are peptide chains which are cell specific and are biocompatible, noninvasive type of delivery vehicle which can transport siRNA, protein, peptides, macromolecules, pDNA, etc. into the cell effectively. Therefore, this review focuses on the structure, type, and method of preparation of PLHNs also about the uptake mechanism of CPPs and concludes with the therapeutic application of PLHNs surface modified with the CPPs and their theranostics.

Cell migration induces apoptosis in osteosarcoma cell via inhibition of Wnt-β-catenin signaling pathway

The current design scheme on anti-cancer materials is mainly through tuning the mechanical properties of the materials to induce apoptosis in cancer cells, with the involvement of Rho/ROCK signaling pathway. We hypothesize that tuning the motility is another potential important approach to modifying the tumor microenvironment and inducing tumor apoptosis. To this aim, we have prepared RGD-modified substrates to regulate cell motility through modification of RGD with different concentrations, and systematically examined the effect of motility on the apoptosis of tumor cells, and the potential involvement of Wnt signaling pathway. Our studies indicated that RGD modification could be readily used to tune the motility of cancer cells. High RGD concentration significantly suppressed the migration of cancer cells, leading to significantly increased apoptosis rate, about three times of that of the unmodified samples. Western-blot analysis also showed that cell with low motility expressed more caspase-3 and PARP proteins. Further RNA sequence study strongly suggested that low motility inhibited the canonical Wnt signaling pathway, which in turn led to the activation of the mitochondria-associated caspase signaling pathway, and ultimately to the apoptosis of osteosarcoma cells. Activation of the Wnt-β-catenin pathway through HLY78 significantly suppressed the apoptosis of MG-63 cells, further suggesting the critical role of Wnt pathway in motility-regulated-apoptosis of tumor cells. Our findings shed insights to understand the underlying mechanisms that induced the tumor cell apoptosis, and might provide new strategy for designing the novel anti-tumor materials.

Bifunctional Compounds as Molecular Degraders for Integrin-Facilitated Targeted Protein Degradation

As effective ways to regulate protein levels, targeted protein degradation technologies have attracted great attention in recent years. Here, we established a novel integrin-facilitated lysosomal degradation (IFLD) strategy to degrade extracellular and cell membrane proteins using bifunctional compounds as molecular degraders. By conjugation of a target protein-binding ligand with an integrin-recognition ligand, the resulting molecular degrader proved to be highly efficient to induce the internalization and subsequent degradation of extracellular or cell membrane proteins in an integrin- and lysosome-dependent manner. As demonstrated in the development of BMS-L1-RGD, which is an efficient programmed death-ligand 1 (PD-L1) degrader validated both in vitro and in vivo, the IFLD strategy expands the toolbox for regulation of secreted and membrane-associated proteins and thus has great potential to be applied in chemical biology and drug discovery.

Efficacy analysis of targeted nanodrug for non-small cell lung cancer therapy

Biological macromolecules have been widely used as biomedical carriers in treating non-small cell lung cancer (NSCLC) due to their biocompatibility, targeting, biodegradability, and antitumor efficacy. Nanotechnology has been used in clinics to treat many diseases, including cancer. Nanoparticles (NPs) can accumulate drugs into tumors because of their enhanced permeability and retention (EPR) effects. However, the lack of active targeting ligands affects NPs drug delivery. Arginine-glycine-aspartic (RGD), as a targeting ligand, has distinct advantages in targeting and safety. In the present study, an RGD peptide-modified nanogel called RGD−polyethylene glycol−poly (L-phenylalanine-co-L-cystine) (RGD−PEG−P (LP-co-LC−P (LP-co-LC) was investigated to deliver vincristine (VCR) as NSCLC therapy. The VCR-loaded targeted nanoparticle (RGD-NP/VCR) demonstrated excellent antitumor efficacy compared to the free drug (VCR) and untargeted nanoparticle (NP/VCR) without any significant side effects. RGD-NP/VCR has better tumor inhibition and fewer side effects, indicating its potential benefit in NSCLC treatment.

Evaluation of 99m Tc-3PRGD2 SPECT imaging on angiogenesis in animal models of lung cancer

BACKGROUND

The main purpose of the study was to evaluate the activity and selectivity of ^99m Tc-3PRGD₂ SPECT/CT and ¹⁸ F-FDG PET-CT in order to detect the neovascularization of A549 cell subcutaneously transplanted tumors, and clarify the relationship among tumor vasculature, hypoxia and cell proliferation in the tumor microenvironment.

METHODS

We established a subcutaneous tumor model, and used ^99m Tc-3PRGD₂ SPECT/CT and ¹⁸ F-FDG PET-CT when the average tumor size reached 0.3-0.5 cm³ . The mice were anesthetized and sacrificed and the tumors were completely removed for frozen section analysis. We subsequently evaluated the status of neovascularization, hypoxia, as well as cell proliferation via immunofluorescence staining (IF) by detecting CD31, pimonidazole and EdU, respectively.

RESULTS

There was a significant positive correlation (r = 0.88, p < 0.05) between the microvascular density (41.20 ± 18.60) and tumor to nontumor ratio (T/M), which was based on the value of ^99m Tc-3PRGD₂ (4.20 ± 1.33); meanwhile, no significance (r = -0.16, p > 0.05) was found between the T/M and hypoxic area (116.71 ± 9.36). Neovascular proliferation was particularly vigorous in the parenchymal region of the tumor, while the cells around the cavity were generally hypoxic. ^99m TC-3PRGD₂ SPECT/CT was more specific than ¹⁸ F-FDG PET-CT in detecting malignant tumors.

CONCLUSION

Both ^99m TC-3PRGD₂ and ¹⁸ F-FDG PET-CT can be used for the detection of malignant tumors, but the specificity and accuracy of ^99m TC-3PRGD₂ are better. The subcutaneous tumors showed a heterogeneous microenvironment as a result of neovascularization, a high proliferation rate of cancer cells as well as subsequent hypoxia, while most of the hypoxic areas appeared around the cavities of the vessels.

Potential 18F-RGD PET/CT and DCE-MRI Imaging-Based Biomarkers for Postoperative Survival Prediction Among Patients With Newly Diagnosed Glioblastoma Treated With Bevacizumab and Chemoradiotherapy

Purpose

To investigate the ability of potential imaging biomarkers based on ¹⁸F-AlF-NOTA-PRGD2 positron emission tomography/computed tomography (¹⁸F-RGD PET/CT) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) imaging to predict the response to bevacizumab combined with conventional therapy in postoperative newly diagnosed glioblastoma.

Methods

Twenty patients with newly diagnosed with glioblastoma after surgery were prospectively enrolled to receive bevacizumab plus conventional concurrent radiotherapy and temozolomide (CCRT). ¹⁸F-RGD PET/CT and DCE-MRI were performed at baseline, week 3, and week 10 for each patient. Statistical methods included the analysis of variance (ANOVA), Kaplan–Meier method and Cox proportional hazard analysis.

Results

All patients completed CCRT plus bevacizumab therapy without interruption. The median follow-up time was 33.9 months (95% confidence interval [CI], 28.3-39.5 months). The median progression-free survival (PFS) and overall survival (OS) was 9.66 months (95% CI, 6.20-13.12 months) and 15.89 months (95% CI, 13.89-17.78), respectively. Treatment was generally well tolerated, and there were no Treatment emergent adverse events (TEAEs) with a toxicity grade equal to or exceeding 3 or that led to termination of treatment or patient death.Over the treatment interval of bevacizumab therapy from week 3 to week 10, patients with a large decrease of SUVmean was associated with a better PFS with a hazard ratio (HR) of 6.562, 95% CI (1.318-32.667), p=0.022. According to Kaplan-Meier analysis, patients with a decrease in the SUVmean of more than 0.115 on ¹⁸F-RGD PET/CT had a longer PFS than those with a decrease in the SUVmean of 0.115 or less (12.25 months vs.7.46 months, p=0.009). For OS, only a small decrease of Ktrans was also found to have certain prognostic value (HR=0.986, 95% CI (0.975-0.998), p=0.023). Patients with a decrease in Ktrans larger than 37.03 (min-1) on DCE-MRI had worse OS than those with a decrease in Ktrans of 37.03 (min-1) or less (15.93 months vs. 26.42 months, p=0.044).

Conclusion

¹⁸F-RGD PET/CT and DCE-MRI may be valuable in evaluating the response of glioblastoma to treatment with the combination of bevacizumab and CCRT, with a greater decrease in SUV_mean predicting better PFS as well as a small decrease in K^trans predicting improved OS.

Peptide therapeutics in the management of metastatic cancers

Cancer remains a leading health concern threatening lives of millions of patients worldwide. Peptide-based drugs provide a valuable alternative to chemotherapeutics as they are highly specific, cheap, less toxic and easier to synthesize compared to other drugs. In this review, we have discussed various modes in which peptides are being used to curb cancer. Our review highlights specially the various anti-metastatic peptide-based agents developed by targeting a plethora of cellular factors. Herein we have given a special focus on integrins as targets for peptide drugs, as these molecules play key roles in metastatic progression. The review also discusses use of peptides as anti-cancer vaccines and their efficiency as drug-delivery tools. We hope this work will give the reader a clear idea of the mechanisms of peptide-based anti-cancer therapeutics and encourage the development of superior drugs in the future.

Renal protection induced by physical exercise may be mediated by the irisin/AMPK axis in diabetic nephropathy

In patients with diabetes, it has been suggested that physical exercise may reduce albuminuria and the progression of renal disease. However, the molecular mechanism by which physical exercise protects the kidney in diabetes remains poorly understood. The aim of the present study was to determine the contribution of muscle irisin secretion induced by aerobic physical exercise with the subsequent activation of AMPK for kidney protection under diabetic conditions. Aerobic physical exercise in rats protected the kidney in streptozotocin-induced diabetes. It reduced albuminuria, glomerular hypertrophy, and glomerular expression of collagen IV and fibronectin, as well as markers of kidney inflammation, when compared to sedentary diabetic rats. These effects were associated with elevation in muscle FNDC5/irisin and activity of AMPK in the diabetic kidney. However, the beneficial effects of exercise were lost when the diabetic rats were treated with CycloRGDyK, that in the bone it has been described as an irisin receptor blocker. In cultured human tubular (HK-2) cells, treatment with recombinant irisin counteracted the effect of high glucose in a dose-dependent manner. Irisin, per se, also activated AMPK in HK-2 cells. It is concluded that in diabetes, the renal protective effect of exercise may be mediated by the irisin/AMPK pathway.

Self-Confirming Magnetosomes for Tumor-Targeted T1 /T2 Dual-Mode MRI and MRI-Guided Photothermal Therapy

Nanomaterials as T₁ /T₂ dual-mode magnetic resonance imaging (MRI) contrast agents have great potential in improving the accuracy of tumor diagnosis. Applications of such materials, however, are limited by the complicated chemical synthesis process and potential biosafety issues. In this study, the biosynthesis of manganese (Mn)-doped magnetosomes (MagMn) that not only can be used in T₁ /T₂ dual-mode MR imaging with self-confirmation for tumor detection, but also improve the photothermal conversion efficiency for MRI-guided photothermal therapy (PTT) is reported. The MagMn nanoparticles (NPs) are naturally produced through the biomineralization of magnetotactic bacteria by doping Mn into the ferromagnetic iron oxide crystals. In vitro and in vivo studies demonstrated that targeting peptides functionalized MagMn enhanced both T₁ and T₂ MRI signals in tumor tissue and significantly inhibited tumor growth by the further MRI-guided PTT. It is envisioned that the biosynthesized multifunctional MagMn nanoplatform may serve as a potential theranostic agent for cancer diagnosis and treatment.

pH-Responsive Self-Assembling Peptide-Based Biomaterials: Designs and Applications

Stimuli-responsive peptide-based biomaterials are increasingly gaining interest for various specific and targeted treatments, including drug delivery and tissue engineering. Among all stimuli, pH can be especially useful because endogenous pH changes are often associated with abnormal microenvironments. pH-Responsive amino acids and organic linkers can be easily incorporated into peptides that self-assemble into various nanostructures. Thus, these largely biocompatible and easily tunable platforms are ideal candidates for drug release and as fibrous materials capable of mimicking the native extracellular matrix. In this review, we highlight common design motifs and mechanisms of pH-responsiveness in self-assembling peptide-based biomaterials, focusing on recent advances of these biomaterials applied in drug delivery and tissue engineering. Finally, we suggest future challenges and areas for potential development in pH-responsive self-assembling peptide-based biomaterials.

Bioengineered Protein Nanocage by Small Heat Shock Proteins Delivering mTERT siRNA for Enhanced Colorectal Cancer Suppression

The efficient delivery of small interfering RNA (siRNA) for target gene silencing holds great promise for cancer therapy. Protein nanocages have attracted considerable attention as ideal drug delivery systems because of their material-derived advantages and unique structural properties. However, most studies about siRNA delivery have not indicated the real role of protein nanocages in inhibiting tumor growth in vivo. Herein, we fabricated an efficient siRNA delivery system using a small heat shock protein (Hsp) nanocage decorated with Arg-Gly-Asp (RGD) and the transactivator of transcription (Tat) peptide. Hsp-Tat-RGD NC showed good cellular uptake and lysosomal escape in colorectal cancer cells. In addition, the nanocage could efficiently transfect siRNA into the cytoplasmic area of CT26 cells. Hsp-Tat-RGD NC delivering telomerase reverse transcriptase (TERT)-targeting siRNA could significantly downregulate TERT protein expression and trigger tumor cell apoptosis in vitro. More importantly, Hsp-Tat-RGD/siTERT complexes nearly completely inhibited the tumor growth after five times of treatment in mice bearing CT26 xenograft. Our results demonstrate the great potential of the Tat/RGD-decorated Hsp nanocage as a promising siRNA delivery platform for cancer therapy.

In Situ Self-Assembly of Bispecific Peptide for Cancer Immunotherapy

Precise and effective manipulation of protein functions still faces tremendous challenges. Herein we report a programmable peptide molecule, consisted of targeting and self-assembly modules, that enables specific and highly efficient assembly governed by targeting receptor proteins. Upon binding to the cell membrane receptor, peptide conformation is somewhat stabilized along with decreased self-assembly activation energy, promoting peptide-protein complex oligomerization. We first design a GNNQQNY-RGD peptide (G7-RGD) to recognize integrin α_V β₃ receptor for proof-of-concept study. In the presence of α_V β₃ protein, the critical assembly concentration of free G7-RGD decreases from 525 to 33 μM and the resultant G7-RGD cluster drives integrin receptor oligomerization. Finally, a bispecific assembling peptide antiCD3-G7-RGD is rationally designed for cancer immunotherapy, which validates CD3 oligomerization and concomitant T cell activation, leading to T cell-mediated cancer cell cytolysis.

Tumor angiogenesis at baseline identified by 18F-Alfatide II PET/CT may predict survival among patients with locally advanced non-small cell lung cancer treated with concurrent chemoradiotherapy

Background

The study investigated the predictive value of tumor angiogenesis observed by ¹⁸F-ALF-NOTA-PRGD2 II (denoted as ¹⁸F-Alfatide II) positron emission tomography (PET)/computed tomography (CT) before concurrent chemoradiotherapy (CCRT) for treatment response and survival among patients with locally advanced non-small cell lung cancer (LA-NSCLC).

Methods

Patients with unresectable stage IIIA or IIIB NSCLC (AJCC Cancer Staging 7th Edition) who received CCRT were included in this prospective study. All patients had undergone ¹⁸F-Alfatide PET/CT scanning before CCRT, and analyzed parameters included maximum uptake values (SUV_max) of primary tumor (SUV_P) and metastatic lymph nodes (SUV_LN) and mean uptake value of blood pool (SUV_blood). Tumor-to-background ratios (TBRs) and changes in tumor diameter before and after CCRT (ΔD) were calculated. The ratios of SUV_P to SUV_blood, SUV_LN to SUV_blood, and SUV_P to SUV_LN were denoted as TBR_P, TBR_LN, and T/LN. Short-term treatment response, progression-free survival (PFS), and overall survival (OS) were evaluated.

Results

Of 38 enrolled patients, 28 completed CCRT. SUV_P, SUV_LN, TBR_P, TBR_LN and T/LN showed significant correlation with PFS (all P < 0.05). SUV_P was negatively correlated with OS (P = 0.005). SUV_P and TBR_P were higher in non-responders than in responders (6.55 ± 2.74 vs. 4.61 ± 1.94, P = 0.039; 10.49 ± 7.58 vs. 7.73 ± 6.09, P = 0.023). ΔD was significantly greater in responders (2.78 ± 1.37) than in non-responders (-0.16 ± 1.33, P < 0.001). Exploratory receiver operating characteristic curve analysis identified TBR_P (area under the curve [AUC] = 0.764, P = 0.018), with a cutoff value of 6.52, as the only parameter significantly predictive of the response to CCRT, with sensitivity, specificity, and accuracy values of 71.43%, 78.57%, and 75.00%, respectively. ROC curve analysis also identified SUV_P (AUC = 0.942, P < 0.001, cutoff value 4.64) and TBR_P (AUC = 0.895, P = 0.001, cutoff value 4.95) as predictive of OS with high sensitivity (84.21%, 93.75%), specificity (100.00%, 66.67%), and accuracy (89.29%, 82.14%).

Conclusions

Evaluation of tumor angiogenesis by ¹⁸F-Alfatide II at baseline may be useful in predicting the short-term response to CCRT as well as PFS and OS in patients with LA-NSCLC.

Self-assembling and cellular distribution of a series of transformable peptides

Transformable peptides (TPs) are biomedical materials with unique structures and diverse functionalities that have drawn great interest in material science and nanomedicine. Here, we design a series of TPs with...

Negative Correlation Between 18F-RGD Uptake via PET and Tumoral PD-L1 Expression in Non-Small Cell Lung Cancer

PURPOSE

We investigated the correlation of ¹⁸F-AlF-NOTAPRGD2 (¹⁸F-RGD) uptake during positron emission tomography (PET) with tumoral programmed death-ligand 1 (PD-L1) expression and explored its potential in immune checkpoint inhibitor treatment.

METHODS

Forty-two mice were subcutaneously injected with CMT-167 lung carcinoma cells. A total of 30 mice with good growth tumor and good general condition were selected. ¹⁸F-RGD PET scanning was performed on days 0, 2, 4, 6, 9, and 11 with five mice per day. Immunohistochemistry (IHC) for PD-L1 was performed on each specimen obtained from tumors. Thirty patients with advanced non-small cell lung cancer (NSCLC) were scanned using ¹⁸F-RGD PET/CT, and Milliplex multifactor detection analyzed serum PD-1/PD-L1 expression of twenty-eight of them. Thirteen of them were analyzed immunohistochemically using core needle biopsy samples obtained from primary tumors.

RESULTS

Thirty mice were scanned by ¹⁸F-RGD PET/CT and analyzed for PD-L1 expression in tumor cells by IHC finally. Maximum standard uptake value (SUVmax) and mean SUV (SUVmean) were significantly lower in relatively-higher-PD-L1-expression tumors than in relatively-low-PD-L1-expression tumors (P < 0.05). In patients, the SUVmax was significantly negatively correlated with tumoral PD-L1 expression by IHC (P=0.014). SUVmean, peak SUV (SUVpeak), and gross tumor volume (GTV) were also negatively correlated with PD-L1, but without significance (P > 0.05). SUVmax, SUVmean, SUVpeak, and GTV were negatively correlated with serum PD-1 and PD-L1, but not significantly. According to the receiver operating characteristic curve analysis, significant correlations between SUVmax and tumoral PD-L1 expression in both mice and patients were present (P < 0.05).

CONCLUSION

Higher ¹⁸F-RGD uptake is correlated with depressed PD-L1 expression in tumor cells, and SUVmax is the best parameter to display tumoral expression of PD-L1. ¹⁸F-RGD PET may be useful for reflecting the immune status of NSCLC.

Current understandings and clinical translation of nanomedicines for breast cancer therapy

Breast cancer is one of the most frequently diagnosed cancers that is threatening women's life. Current clinical treatment regimens for breast cancer often involve neoadjuvant and adjuvant systemic therapies, which somewhat are associated with unfavorable features. Also, the heterogeneous nature of breast cancers requires precision medicine that cannot be fulfilled by a single type of systemically administered drug. Taking advantage of the nanocarriers, nanomedicines emerge as promising therapeutic agents for breast cancer that could resolve the defects of drugs and achieve precise drug delivery to almost all sites of primary and metastatic breast tumors (e.g. tumor vasculature, tumor stroma components, breast cancer cells, and some immune cells). Seven nanomedicines as represented by Doxil® have been approved for breast cancer clinical treatment so far. More nanomedicines including both non-targeting and active targeting nanomedicines are being evaluated in the clinical trials. However, we have to realize that the translation of nanomedicines, particularly the active targeting nanomedicines is not as successful as people have expected. This review provides a comprehensive landscape of the nanomedicines for breast cancer treatment, from laboratory investigations to clinical applications. We also highlight the key advances in the understanding of the biological fate and the targeting strategies of breast cancer nanomedicine and the implications to clinical translation.

Integrins as attractive targets for cancer therapeutics

Integrins are transmembrane receptors that have been implicated in the biology of various human physiological and pathological processes. These molecules facilitate cell–extracellular matrix and cell–cell interactions, and they have been implicated in fibrosis, inflammation, thrombosis, and tumor metastasis. The role of integrins in tumor progression makes them promising targets for cancer treatment, and certain integrin antagonists, such as antibodies and synthetic peptides, have been effectively utilized in the clinic for cancer therapy. Here, we discuss the evidence and knowledge on the contribution of integrins to cancer biology. Furthermore, we summarize the clinical attempts targeting this family in anti-cancer therapy development.

Comparison of Linear vs. Cyclic RGD Pentapeptide Interactions with Integrin αvβ3 by Molecular Dynamics Simulations

Simple Summary

The integrin α_vβ₃-RGD motif interaction plays a key role in the progression of malignant tumor. Although two typical cyclic and linear RGD short peptides have been widely used in tumor diagnosis and therapy, little is known about the internal dynamic mechanism for different configurations of RGD peptides with different affinities interacting with the integrin α_vβ₃. Our results showed that the cyclic RGD peptide had a more stable configuration in binding to integrins α_vβ₃, which depended on the higher binding energy and higher static electrical energy, especially in the interaction between Asp^RGD-MIDAS. The steered molecular dynamics simulation showed a stronger interaction for the cyclic RGD-integrin α_vβ₃ system than the linear one, with a larger dissociation force (average peak force) and more time to dissociate. Our findings provide insights into the dynamics of integrin α_vβ₃ interactions with linear and cyclic RGD ligands and offer some new therapeutic approaches for the design and development of novel antitumor drugs.

Abstract

Integrin α_vβ₃ interacting with the short Arg-Gly-Asp (RGD) motif plays a critical role in the progression of several types of tumors. However, the effects of the RGD structure (cyclic or linear) with integrin α_vβ₃ at the atomic level remain poorly understood. Here, we performed association and dissociation dynamic simulations for integrin α_vβ₃ in complex with a linear or cyclic pentapeptide by steered molecular dynamics simulations. Compared with cyclic RGD, the linear RGD peptide triggers instability of the configurational changes, mainly resting with the RGD domain due to its flexibility. The main interaction energy between Mg²⁺ and cyclic RGD is much stronger than that of the linear RGD system by the well shield to lessen attacks by free water molecules. The force-dependent dissociation results show that it is easier for linear RGD peptides to leave the active site and much quicker than the cyclic RGD ligand, whereas it is harder to enter the appropriate active binding site in linear RGD. The Ser¹²³-Asp^RGD bond may play a critical role in the allosteric pathway. Our findings provide insights into the dynamics of α_vβ₃ interactions with linear and cyclic RGD ligands and contribute to the application of RGD-based strategies in preclinical therapy.

Extracellular Matrix: Emerging Roles and Potential Therapeutic Targets for Breast Cancer

Increasing evidence shows that the extracellular matrix (ECM) is an important regulator of breast cancer (BC). The ECM comprises of highly variable and dynamic components. Compared with normal breast tissue under homeostasis, the ECM undergoes many changes in composition and organization during BC progression. Induced ECM proteins, including fibrinogen, fibronectin, hyaluronic acid, and matricellular proteins, have been identified as important components of BC metastatic cells in recent years. These proteins play major roles in BC progression, invasion, and metastasis. Importantly, several specific ECM molecules, receptors, and remodeling enzymes are involved in promoting resistance to therapeutic intervention. Additional analysis of these ECM proteins and their downstream signaling pathways may reveal promising therapeutic targets against BC. These potential drug targets may be combined with new nanoparticle technologies. This review summarizes recent advances in functional nanoparticles that target the ECM to treat BC. Accurate nanomaterials may offer a new approach to BC treatment.

Irisin Regulating Skeletal Response to Endurance Exercise in Ovariectomized Mice by Promoting Akt/β-Catenin Pathway

Purpose: Thought irisin is recognized as a pivotal modulator for bone formation, its role in regulating skeletal response to exercise training remains unknown. Therefore, we aimed to determine the change of irisin in response to 8-week exercise training and its role in regulating the effects of exercise on bone loss in ovariectomized (Ovx) mice.

Methods: Forty 3-month old female C57BL/6 mic were randomly allocated into four groups: (1) Sham-operated (Sham); (2) ovariectomized; (3) Ovx plus 8-week downhill running exercise (Ex); (4) Ovx plus exercise and received twice weekly injection of cyclo RGDyk protein (a putative anti-irisin receptor agents) (ExRg).

Results: Ex group showed enhanced cortical and trabecular volumetric bone mineral density (vBMD) (p < 0.05), improved bone microarchitecture, and increased intensity of alkaline phosphatase positive (ALP⁺) cells compared with Ovx group. However, cyclo RGDyk administration weakened the exercise-related improvement of vBMD, BV/TV, and ALP intensity in bone. Serum estradiol, irisin, and bone alkaline phosphatase were higher, whereas circulating tartrate-resistant acid phosphatase was lower in Ex group compared with Ovx group (p < 0.05). Exercise promoted mRNA expression of fibronectin type III domain-containing protein 5 (FNDC5), Akt and β-catenin, and enhanced protein levels of FNDC5, the ratio of phosphorylated Akt (p-Akt) to Akt, and β-catenin (p < 0.05). When irisin pathways were blocked with cyclo RGDyk, increment of Akt, p-Akt/Akt, and β-catenin in Ex mice were attenuated.

Conclusion: It is suggested that irisin plays a potential role in regulating skeletal response to exercise partly through its interaction with Akt/β-catenin pathways.

Recent advances in the synthesis of (99mTechnetium) based radio-pharmaceuticals

Technetium radionuclide (99mTc) has excellent extent of disintegration properties and occupies a special place in the field of nuclear medicinal chemistry and other health disciplines. Current review describes recent approaches of synthesis in detailed ways for radio-pharmaceuticals of technetium which have been developed to treat and diagnose the biotic disorders. These technetium labeled radio-pharmaceuticals have been established to apply in the field of diagnostic nuclear medicine especially for imaging of different body parts such as brain, heart, kidney, bones and so on, through single photon emission computed tomography (SPECT) that is thought to be difficult to image such organs by using common X-ray and MRI (Magnetic Resonance Imaging) techniques. This review highlights and accounts an inclusive study on the various synthetic routes of technetium labeled radio-pharmaceuticals using ligands with various donor atoms such as carbon, nitrogen, sulphur, phosphorus etc. These compounds can be utilized as next generation radio-pharmaceuticals.

Molecular design and anti-melanoma activity of a novel bullfrog antibacterial peptide RGD-chimera

Melanoma is a common malignant skin tumor, which is the only fatal skin tumor at present. Melanoma has a high degree of malignancy and metastasis. The activity of modified Temporin-La (T-La) peptides from bullfrog skin were evaluated for antitumor activity and improved targeting in melanoma cells. The amino acid sequence of T-La was modified, resulting in the antitumor peptide, T-La (FS). T-La and T-La (FS) were coupled to the RGD small molecule polypeptide to form the chimeric peptides RGD-T-La and RGD-T-La (FS), respectively. The secondary structures for the peptides, evaluated using circular dichroism, were found to be α-helical. The structure of T-La was evaluated using bioinformatics. In addition, the antitumor effects of the modified peptide and the targeting of RGD chimeric peptide to the tumor in vivo and in vitro were analyzed. Antitumor activity was measured in vitro using the MTT assay. Tumor cells with high integrin αvβ3 expression were detected using flow cytometry, and tumor cells were screened for sensitivity to RGD-T-La (FS) to establish a tumor model in nude mice. The effects of the peptides on tumor cells were measured using laser confocal microscopy in real-time. The mechanism of the peptide antitumor activity in tumor cells was evaluated with scanning electron microscopy. B16 melanoma cells were the most sensitive to the peptides, for which the cell survival rate was 24.65% for 10 µg/ml RGD-T-La (FS). RGD-La (FS) had a rapid effect on tumor cells. RGD chimeric polypeptides exhibited site-targeting cytotoxic effects in tumor cells. In the B16 melanoma mouse model, the peptides exhibited antitumor effects against early melanoma development and induced tumor apoptosis, possibly by inhibiting VEGF and promoting caspase-3 expression. Overall, the present study provides a scientific basis for the application of small molecule antimicrobial peptides as targeted antitumor agents and lays the foundation for the clinical application of these peptides as antitumor drugs.

18F-RGD PET/CT imaging reveals characteristics of angiogenesis in non-small cell lung cancer

Background

The objective of this study was to explore the benefit of ¹⁸F-AlF-NOTA-PRGD2 positron emission tomography/computed tomography (denoted as ¹⁸F-RGD PET/CT) imaging for determining the clinical pathologic features of non-small cell lung cancer (NSCLC).

Methods

Seventy-two patients with NSCLC (37 cases of adenocarcinoma and 35 cases of squamous carcinoma) were enrolled to receive ¹⁸F-RGD PET/CT scanning pretreatment. The peak standard uptake value (SUV_peak), mean standard uptake value (SUV_mean), angiogenic tumor volume (ATV) and total lesion angiogenesis (TLA) of tumors were determined using an automated contouring program. Cases were classified according to the tumor, lymph node, metastasis (TNM) stage.

Results

Significant differences in ATV and TLA were observed among T1, T2, T3 and T4 cases (ATV, P=0.000; TLA, P=0.000). ATV and TLA also differed significantly among cases of clinical stage I, II, III and IV (ATV, P=0.002; TLA, P=0.011). However, no significant differences in any values were observed between stage III and IV NSCLC cases (SUV_peak, P=0.675; SUV_mean, P=0.668; ATV, P=0.52; TLA, P=0.634). All assessed values were higher in squamous cell carcinoma cases than in adenocarcinoma cases (SUV_peak, P=0.045; SUV_mean, P=0.014; ATV, P=0.003; TLA, P=0.001). For clinical stage III and IV cases specifically, SUV_peak, SUV_mean, and TLA were higher for squamous cell carcinoma than for adenocarcinoma (SUV_peak, P=0.015; SUV_mean, P=0.009; TLA, P=0.036).

Conclusions:¹⁸F-RGD PET/CT imaging revealed the presence of increased angiogenesis in the tumor microenvironment of NSCLC, especially squamous cell carcinoma, and thus may be valuable in planning therapeutic regimens for individual patients.

Ultrasound-Aided Targeting Nanoparticles Loaded with miR-181b for Anti-Inflammatory Treatment of TNF-α-Stimulated Endothelial Cells

Gene therapy is an emerging therapeutic strategy used in clinics. Ultrasound-mediated gene transfection possesses great potential as a secure and available approach for gene delivery. However, transfection efficiency and targeting ability remain challenging. In this study, we developed a kind of ultrasound-aided and targeting nanoparticles for microRNA delivery. These nanoparticles carrying nucleic acids were prepared with cationic poly-(amino acid) encapsulated with perfluoropentane. The formulated nanoparticles were stabilized with negatively charged PGA-PEG-RGD peptide coating. Ultrasound imaging and specific gene transfection using this nanocarrier could be implemented simultaneously. Upon treatment with ultrasound irradiation, phase transition was induced in the nanoparticles and they generated acoustic cavitation, resulting in enhanced gene transfection against the endothelial cells. With the overexpression of miR-181b loaded by the nanoparticles, the TNF-α-stimulated endothelial cells were effectively rescued from the inflammatory state through the protection of cell viability and suppression of cell adhesion.

Conformational Dynamics in Extended RGD-Containing Peptides

RGD is a prolific example of a tripeptide used in biomaterials for cell adhesion, but the potency of free or surface-bound RGD tripeptide is orders-of-magnitude less than the RGD domain within natural proteins. We designed a set of peptides with varying lengths, composed of fragments of fibronectin protein whose central three residues are RGD, in order to vary their conformational behavior without changing the binding site's chemical environment. With these peptides, we measure the conformational dynamics and transient structure of the active site. Our studies reveal how flanking residues affect conformational behavior and integrin binding. We find that disorder of the binding site is important to the potency of RGD peptides and that transient hydrogen bonding near the RGD site affects both the energy landscape roughness of the peptides and peptide binding. This phenomenon is independent of longer-range folding interactions and helps explain why short binding sequences, including RGD itself, do not fully replicate the integrin-targeting properties of extracellular matrix proteins. Our studies reinforce that peptide binding is a holistic event and fragments larger than those directly involved in binding should be considered in the design of peptide epitopes for functional biomaterials.

Advances in mathematical models of the active targeting of tumor cells by functional nanoparticles

BACKGROUND AND OBJECTIVE

The process of nanoparticles (NPs) entering blood circulation to actively target tumor cells involves four stages-the transport of NPs in blood vessels, transvascular transport of NPs, transport of NPs in the tumor interstitial matrix and entry of NPs into tumor cells. These four stages are a complex process involving mechanical, physical, biochemical, and biophysical factors, the tumor microenvironment (TME) and properties of NPs play important roles in this process. Because this process involves a large number of factors and is very complex, it is difficult to study with conventional methods.

METHODS

Using mathematical models for simulation is suitable for addressing this complex situation and can describe the complexity well.

RESULTS

This work focuses on the theoretical simulation of NPs that target tumor cells to illustrate the effects of the abnormal microenvironment of tumors and properties of NPs on the transport process. Mathematical models constructed by different methods are enumerated. Through studying these mathematical models, different methods to overcome nanoparticle (NP) transport obstacles are illustrated.

CONCLUSIONS

It is necessary to construct a theoretical model of active targeting nanodrug delivery under the coupling of micro-flow field and specific binding force field, and to simulate and analyze the delivery process at mesoscopic scale using computational fluid dynamics (CFD) method, so as to reveal the law and characteristics of drug delivery and cell uptake in the micro-environment of tumors in vivo. The methods and techniques discussed can serve as the basis for systematic studies of active targeting of functional nanoparticles to tumor cells.

Transmission blockage of an orthotospovirus using synthetic peptides

Orthotospoviruses are acquired by thrips during feeding on infected tissue. Virions travel through the foregut and enter midgut epithelial cells through the interaction between the viral glycoproteins and cellular receptors. Glycoprotein RGD motifs and N-linked glycosylation sites have been predicted to mediate receptor binding or play important roles in virus entry into host cells, yet their function needs to be validated. In this study, peptides derived from the soybean vein necrosis virus N glycoprotein were utilized to identify critical regions in virus-vector interactions. Transmission mediated by single Neohydatothrips variabilis dropped by more than 2/3 when thrips were fed on peptide NASIAAAHEVSQE or the combination of NASIRGDHEVSQE and RLTGECNITKVSLTN when compared to the controls; indicating that this strategy could significantly reduce transmission efficiency, opening new avenues in the control of diseases caused by orthotospoviruses.

Recent progress in biomedical applications of RGD-based ligand: From precise cancer theranostics to biomaterial engineering: A systematic review

Arginine-glycine-aspartic acid (RGD) peptide family is known as the most prominent ligand for extracellular domain of integrin receptors. Specific expression of these receptors in various tissue of human body and tight association of their expression profile with various pathophysiological conditions made these receptors a suitable targeting candidate for several disease diagnosis and treatment as well as regeneration of various organs. For these reasons, various forms of RGD-based integrins ligands have been greatly used in biomedical studies. Here, we summarized the last decade application progress of RGD for cancer theranostics, control of inflammation, thrombosis inhibition and critically discussed the effect of RGD peptides structure and sequence on the efficacy of gene/drug delivery systems in preclinical studies. Furthermore, we will show recent advances in application of RGD functionalized biomaterials for various tissue regenerations including cornea repair, artificial neovascularization and bone tissue regeneration. Finally, we analyzed clinically translatability of RGD peptides, considering examples of integrin ligands in clinical trials. In conclusion, prospects on using RGD peptide for precise drug delivery and biomaterial engineering are well discussed.

Self-assembling peptide-based nanodrug delivery systems

Self-assembling peptide-based nanodrug delivery systems (NDDs), consisting of naturally occurring amino acids, not only share the advantages of traditional nanomedicine but also possess the unique properties of excellent biocompatibility, biodegradability, flexible responsiveness, specific biological function, and synthetic feasibility. Physical methods, enzymatic reaction, chemical reaction, and biosurface induction can yield versatile peptide-based NDDs; flexible responsiveness is their main advantage. Different functional peptides and abundant covalent modifications endow such systems with precise controllability and multifunctionality. Inspired by the above merits, researchers have taken advantage of the self-assembling peptide-based NDDs and achieved the accurate delivery of drugs to the lesion site. The present review outlines the methods for designing self-assembling peptide-based NDDs for small-molecule drugs, with an emphasis on the different drug delivery strategies and their applications in using peptides and peptide conjugates.

Ligand-Modified Cell Membrane Enables the Targeted Delivery of Drug Nanocrystals to Glioma

The safe and efficient delivery of chemotherapeutic agents remains critical to anticancer therapy. Herein, we report on a targeted drug delivery system based upon a modified cell membrane coating technique and drug nanocrystals (NCs). Specifically, red blood cell (RBC) membrane was modified with targeting peptides through a facile insertion method involving avidin-biotin interactions. The RBC membrane-coated drug NCs (RBC-NCs) exhibited high drug loading, long-term stability, excellent biocompatibility, and prolonged retention time, all of which make them suitable for effective drug delivery. When modified with the tumor-targeting peptide c(RGDyK), the resulting RGD-RBC-NCs showed superior tumor accumulation and therapeutic efficacy both in mice bearing a subcutaneous tumor as well as orthotropic glioma. RBC-NC therapeutics can be readily generalized to the delivery of various drugs and for the treatment of a wide range of cancers.