Multimeric Presentation of RGD Peptidomimetics Enhances Integrin Binding and Tumor Cell Uptake

Prospective study of 99mTc-3PRGD2 SPECT/CT diagnosing metastatic lymph nodes in esophageal squamous cell carcinoma

BACKGROUND

Lymph node (LN) metastasis is a significant prognostic factor for esophageal squamous cell carcinoma (ESCC), and there are no satisfactory methods for accurately predicting metastatic LNs. The present study aimed to assess the efficacy of 99mTc-3PRGD2 single-photon emission computed tomography (SPECT)/computed tomography (CT) for diagnosing metastatic LNs in ESCC.

METHODS

A total of 15 enrolled patients with ESCC underwent 99mTc-3PRGD2 SPECT/CT and 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) examinations preoperatively. High-definition bone carving reconstruction technology (HD-xSPECT Bone) was applied to quantitatively assess the LN's SUVmax via SPECT/CT. The two methods were compared for diagnosing metastatic LNs with pathology as the gold standard.

RESULTS

Among 15 patients, 23 metastatic lymph node stations (mLNSs) were predicted by SPECT/CT, with a mean SUVmax of 2.71 ± 1.34, of which 15 were pathologically confirmed; 32 mLNSs were predicted by PET/CT with a mean SUVmax of 4.41 ± 4.02, of which 17 were pathologically confirmed. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SPECT/CT for diagnosing metastatic LNs were 62.50%, 91.30%, 85.34%, 65.22%, and 90.32%, respectively, and those of PET/CT were 70.83%, 83.70%, 81.03%, 53.13%, and 91.67%, respectively. There was no significant difference in sensitivity (p = 0.061) or specificity (p = 0.058) between the two methods. The AUCSPECT/CT was 0.816 and the SUVmax threshold was 2.5.

CONCLUSION

99mTc-3PRGD2 SPECT/CT might be an effective method for diagnosing metastatic LNs in ESCC, especially in combination with HD-xSPECT Bone. The diagnostic efficiency of this method was noninferior to that of 18F-FDG PET/CT. The SUVmax threshold of 2.5 showed the highest agreement with the pathology findings.

Small molecule- and peptide-drug conjugates addressing integrins: A story of targeted cancer treatment

Targeted cancer treatment should avoid side effects and damage to healthy cells commonly encountered during traditional chemotherapy. By combining small molecule or peptidic ligands as homing devices with cytotoxic drugs connected by a cleavable or non-cleavable linker in peptide-drug conjugates (PDCs) or small molecule-drug conjugates (SMDCs), cancer cells and tumours can be selectively targeted. The development of highly affine, selective peptides and small molecules in recent years has allowed PDCs and SMDCs to increasingly compete with antibody-drug conjugates (ADCs). Integrins represent an excellent target for conjugates because they are overexpressed by most cancer cells and because of the broad knowledge about native binding partners as well as the multitude of small-molecule and peptidic ligands that have been developed over the last 30 years. In particular, integrin αVβ3 has been addressed using a variety of different PDCs and SMDCs over the last two decades, following various strategies. This review summarises and describes integrin-addressing PDCs and SMDCs while highlighting points of great interest.

Engineered Exosomes Carrying miR-588 for Treatment of Triple Negative Breast Cancer Through Remodeling the Immunosuppressive Microenvironment

Background

The morbidity and mortality of triple-negative breast cancer (TNBC) are still high, causing a heavy medical burden. CCL5, as a chemokine, can be involved in altering the composition of the tumor microenvironment (TME) as well as the immunosuppressive degree, and has become a very promising target for the treatment of TNBC. Dysregulation of microRNAs (miRNAs) in tumor tissues is closely related to tumor progression, and its utilization can be used to achieve therapeutic purposes. Engineered exosomes can avoid the shortcomings of miRNAs and also enhance their targeting and anti-tumor effects through engineering. Therefore, we aimed to create a cRGD-modified exosome for targeted delivery of miR-588 and to investigate its effect in remodeling immunosuppressive TME by anchoring CCL5 in TNBC.

Methods

In this study, we loaded miR-588 into exosomes using electroporation and modified it with cRGD using post insertion to obtain cRGD-Exos/miR-588. Transmission electron microscopy (TEM), nanoparticle tracking assay technique (NTA), Western Blots, qPCR, and flow cytometry were applied for its characterization. CCK-8, qPCR and enzyme-linked immunosorbent assay (ELISA), in vivo fluorescence imaging system, immunohistochemistry and H&E staining were used to explore the efficacy as well as the mechanism at the cellular level as well as in subcutaneous graft-tumor nude mouse model.

Results

The cRGD-Exos/miR-588 was successfully constructed and had strong TNBC tumor targeting in vitro and in vivo. Meanwhile, it has significant efficacy on TME components affected by CCL5 and the degree of immunosuppression, which can effectively control TNBC with good safety.

Conclusion

In this experiment, cRGD-Exos/miR-588 was prepared to remodel immunosuppressive TME by anchoring CCL5, which is affected by the vicious cycle of immune escape. Overall, cRGD-Exos/miR-588 explored the feasibility of targeting TME for the TNBC treatment, and provided a competitive delivery system for the engineered exosomes to deliver miRNAs for antitumor therapy drug.

RGD peptide in cancer targeting: Benefits, challenges, solutions, and possible integrin-RGD interactions

RGD peptide can be found in cell adhesion and signaling proteins, such as fibronectin, vitronectin, and fibrinogen. RGD peptides' principal function is to facilitate cell adhesion by interacting with integrin receptors on the cell surface. They have been intensively researched for use in biotechnology and medicine, including incorporation into biomaterials, conjugation to medicinal molecules or nanoparticles, and labeling with imaging agents. RGD peptides can be utilized to specifically target cancer cells and the tumor vasculature by engaging with these integrins, improving drug delivery efficiency and minimizing adverse effects on healthy tissues. RGD-functionalized drug carriers are a viable option for cancer therapy as this focused approach has demonstrated promise in the future. Writing a review on the RGD peptide can significantly influence how drugs are developed in the future by improving our understanding of the peptide, finding knowledge gaps, fostering innovation, and making drug design easier.

Non-Canonical Amino Acids as Building Blocks for Peptidomimetics: Structure, Function, and Applications

This review provides a fresh overview of non-canonical amino acids and their applications in the design of peptidomimetics. Non-canonical amino acids appear widely distributed in nature and are known to enhance the stability of specific secondary structures and/or biological function. Contrary to the ubiquitous DNA-encoded amino acids, the structure and function of these residues are not fully understood. Here, results from experimental and molecular modelling approaches are gathered to classify several classes of non-canonical amino acids according to their ability to induce specific secondary structures yielding different biological functions and improved stability. Regarding side-chain modifications, symmetrical and asymmetrical α,α-dialkyl glycines, Cα to Cα cyclized amino acids, proline analogues, β-substituted amino acids, and α,β-dehydro amino acids are some of the non-canonical representatives addressed. Backbone modifications were also examined, especially those that result in retro-inverso peptidomimetics and depsipeptides. All this knowledge has an important application in the field of peptidomimetics, which is in continuous progress and promises to deliver new biologically active molecules and new materials in the near future.

Targeting JWA for Cancer Therapy: Functions, Mechanisms and Drug Discovery

Simple Summary

JWA has been identified as a potential therapeutic target for several cancers. In this review, we summarize the tumor suppressive functions of the JWA gene and its role in anti-cancer drug development. The focus is on elucidating the key regulatory proteins up and downstream of JWA and their signaling networks. We also discuss current strategies for targeting JWA (JWA peptides, small molecule agonists, and JWA-targeted Pt (IV) prodrugs).

Abstract

Tumor heterogeneity limits the precision treatment of targeted drugs. It is important to find new tumor targets. JWA, also known as ADP ribosylation factor-like GTPase 6 interacting protein 5 (ARL6IP5, GenBank: AF070523, 1998), is a microtubule-associated protein and an environmental response gene. Substantial evidence shows that JWA is low expressed in a variety of malignancies and is correlated with overall survival. As a tumor suppressor, JWA inhibits tumor progression by suppressing multiple oncogenes or activating tumor suppressor genes. Low levels of JWA expression in tumors have been reported to be associated with multiple aspects of cancer progression, including angiogenesis, proliferation, apoptosis, metastasis, and chemotherapy resistance. In this review, we will discuss the structure and biological functions of JWA in tumors, examine the potential therapeutic strategies for targeting JWA and explore the directions for future investigation.

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.

Discovery, affinity maturation and multimerization of small molecule ligands against human tyrosinase and tyrosinase-related protein 1

Human tyrosinase (hTYR) and tyrosinase-related protein 1 (hTYRP1) are closely-related enzymes involved in the synthesis of melanin, which are selectively expressed in melanocytes and, in a pathological context, in melanoma lesions. We used a previously described tyrosinase inhibitor (Thiamidol™) and DNA-encoded library technology for the discovery of novel hTYR and hTYRP1 ligands, that could be used as vehicles for melanoma targeting. Performing de novo selections with DNA-encoded libraries, we discovered novel ligands capable of binding to both hTYR and hTYRP1. More potent ligands were obtained by multimerizing Thiamidol™ moieties, leading to homotetrameric structures that avidly bound to melanoma cells, as revealed by flow cytometry. These findings suggest that melanoma lesions may, in the future, be targeted not only by monoclonal antibody reagents but also by small organic ligands.

A series of different strategies were oriented toward the discovery of small molecule ligands binding to the human version of tyrosinase (hTYR) and tyrosinase-related protein 1 (hTYRP1), which may represent the basis for novel treatments of melanoma.