Transformable peptide nanoparticles arrest HER2 signalling and cause cancer cell death in vivo

Mechanisms of Drug Resistance and Use of Nanoparticle Delivery to Overcome Resistance in Breast Cancers

Breast cancer is the leading cancer type diagnosed among women in the world. Unfortunately, drug resistance to current breast cancer chemotherapeutics remains the main challenge for a higher survival rate. The recent progress in the nanoparticle platforms and distinct features of nanoparticles that enhance the efficacy of therapeutic agents, such as improved delivery efficacy, increased intracellular cytotoxicity, and reduced side effects, hold great promise to overcome the observed drug resistance. Currently, multifaceted investigations are probing the resistance mechanisms associated with clinical drugs, and identifying new breast cancer-associated molecular targets that may lead to improved therapeutic approaches with the nanoparticle platforms. Nanoparticle platforms including siRNA, antibody-specific targeting and the role of nanoparticles in cellular processes and their effect on breast cancer were discussed in this article.

Functional bionanomaterials for cell surface engineering in cancer immunotherapy

The cell surface is the forward position in cancer immunotherapy, with surface ligand and receptor interactions between various cells for determining immune privilege or recognition. Therefore, cell surface engineering (CSE) that manipulates the surface interactions between the immune effector cells (IECs) and tumor cells represents a promising means for eliciting effective anticancer immunity. Specifically, taking advantage of the development in biomaterials and nanotechnology, the use of functional bionanomaterials for CSE is attracting more and more attention in recent years. Rationally designed functional biomaterials have been applied to construct artificial functional modules on the surface of cells through genetic engineering, metabolic labeling, chemical conjugation, hydrophobic insertion, and many other means, and the CSE process can be performed both ex vivo and in vivo, on either IECs or tumor cells, and results in enhanced anticancer immunity and various new cancer immunity paradigms. In this review, we will summarize the recent exciting progresses made in the application of functional bionanomaterials for CSE especially in establishing effective recognition and interaction between IECs and tumor cells.

Programmed Size-Changeable Nanotheranostic Agents for Enhanced Imaging-Guided Chemo/Photodynamic Combination Therapy and Fast Elimination

An ideal nanotheranostic agent should be able to achieve efficient tumor accumulation, retention, and fast elimination after its theranostic functions exhausts. However, there is an irreconcilable contradiction on optimum sizes for effective tumor retention and fast elimination. Herein, a programmed size-changeable nanotheranostic agent based on polyprodrug-modified iron oxide nanoparticles (IONPs) and aggregation-induced emission photosensitizer is developed for enhanced magnetic resonance imaging (MRI)-guided chemo/photodynamic combination therapy. The nano-sized theranostic agents with an initial diameter of about 90 nm can accumulate in tumor tissue through passive targeting. In the acidic tumor microenvironment, large aggregates of IONPs are formed, realizing enhanced tumor retention and MR signal enhancement. Under the guidance of MRI, light irradiation is applied to the tumor site for triggering the generation of reactive oxygen species and drug release. Moreover, after chemo/photodynamic combination therapy, the large-sized aggregates are re-dispersed into small-sized IONPs for fast elimination, reducing the risk of toxicity caused by long-term retention. Therefore, this study provides a promising size-changeable strategy for the development of nanotheranostic agents.

Multi-stage responsive peptide nanosensor: Anchoring EMT and mitochondria with enhanced fluorescence and boosting tumor apoptosis

Epithelial-mesenchymal transition (EMT) is closely related to tumor metastasis and invasion. Thereinto, mesenchymal tumor mitochondria are the critical target for tumor inhibition. Therefore, real-time in vivo monitoring of EMT as well as inhibiting mesenchymal tumor mitochondria is of great diagnosis and therapy significance. Herein, we construct a multi-stage recognition and morphological transformable self-assembly-peptide nano biosensor ^NDRP which can response the EMT marker and specifically damage the mesenchymal tumor cell in vivo. This nano-molar-affinity sensor is designed and screened with sensitive peptides containing a molecular switching which could be specifically triggered by the receptor to achieve the vesicle-to-fibril transformation in living system with enhanced fluorescent signal. ^NDRP nanosensor could target the tumor lesion in circulatory system, recognize mesenchymal tumor marker DDR2 (Discoidin domain receptor 2) in cellular level and specifically achieve mitochondria in subcellular level as well as damaged mitochondria which could be applied as a in vivo theranostic platform.

Engineering protein theranostics using bio-orthogonal asparaginyl peptide ligases

Background: Protein theranostics integrate both diagnostic and treatment functions on a single disease-targeting protein. However, the preparation of these multimodal agents remains a major challenge. Ideally, conventional recombinant proteins should be used as starting materials for modification with the desired detection and therapeutic functionalities, but simple chemical strategies that allow the introduction of two different modifications into a protein in a site-specific manner are not currently available. We recently discovered two highly efficient peptide ligases, namely butelase-1 and VyPAL2. Although both ligate at asparaginyl peptide bonds, these two enzymes are bio-orthogonal with distinguishable substrate specificities, which can be exploited to introduce distinct modifications onto a protein.

Methods: We quantified substrate specificity differences between butelase-1 and VyPAL2, which provide orthogonality for a tandem ligation method for protein dual modifications. Recombinant proteins or synthetic peptides engineered with the preferred recognition motifs of butelase-1 and VyPAL2 at their respective C- and N-terminal ends could be modified consecutively by the action of the two ligases.

Results: Using this method, we modified an EGFR-targeting affibody with a fluorescein tag and a mitochondrion-lytic peptide at its respective N- and C-terminal ends. The dual-labeled protein was found to be a selective bioimaging and cytotoxic agent for EGFR-positive A431 cancer cells. In addition, the method was used to prepare a cyclic form of the affibody conjugated with doxorubicin. Both modified affibodies showed increased cytotoxicity to A431 cells by 10- and 100-fold compared to unconjugated doxorubicin and the free peptide, respectively.

Conclusion: Bio-orthogonal tandem ligation using two asparaginyl peptide ligases with differential substrate specificities is a straightforward approach for the preparation of multifunctional protein biologics as potential theranostics.

Out-of-the-Box Nanocapsules Packed with On-Demand Hydrophobic Anticancer Drugs for Lung Targeting, Esterase Triggering, and Synergy Therapy

Most anticancer drugs, particularly paclitaxel (PTX), are suffering the challenges of cancer chemotherapy due to their poor water-solubility, high toxicity under effective therapeutic dosages, and multi-drug resistance. Currently, nanoscale drug delivery systems (DDSs) represent an efficient platform to overcome the above challenges. However, those DDSs generally need a careful design of conjugation, complexation, or co-self-assembly. Herein, a facile out-of-the-box nanocapsule is developed not only to be easily packed with on-demand hydrophobic anticancer drugs (up to 76% of loading efficiency for PTX), but also to be loaded with other concomitant drugs for synergy therapy (Itraconazole (ITA) here as P-glycoprotein inhibitor for drug resistance and antiangiogenic agent for combination therapy with PTX). Three kinds of biocompatible poly(ethylene glycol) dimethacrylates (PEGDM) derivatives usually as cross-linking agents are selected and successfully constructed adequate nanocapsules with single monomer as shell materials. More importantly, as-prepared nanocapsules have abilities of esterase triggering and lung targeting. Both in vitro and in vivo studies showed that the drug-loaded nanocapsules can effectively inhibit tumor growth and vascular proliferation in PTX-resistant tumor models without apparent systemic toxicity. The above results demonstrate that the nanocapsule system provides an effective and universal strategy for lung targeting, esterase triggering, and synergy therapy.

Supramolecular Self-Assembly-Facilitated Aggregation of Tumor-Specific Transmembrane Receptors for Signaling Activation and Converting Immunologically Cold to Hot Tumors

Supramolecular self-assembling peptide systems are attracting increasing interest in the field of cancer theranostics. Additionally, transformation of the immunologically cold tumor microenvironment into hot is of great importance for obtaining high antitumor responses for most immunotherapies. However, as far as it is known, there are nearly no studies on self-assembling peptides reported to be able to convert cold to hot tumors. Herein, a self-assembling peptide-based cancer theranostic agent (named DBT-2FFGYSA) is designed and synthesized, which can target tumor-specific transmembrane Eph receptor A2 (EphA2) receptors selectively and make the receptors form large aggregates. Such aggregate formation promotes the cross-phosphorylations among EphA2 receptors, leading to signal transduction of antitumor pathway. As a consequence, DBT-2FFGYSA can not only visualize EphA2 receptors in a fluorescence turn-on manner, but also specifically suppress the EphA2 receptor-overexpressed cancer cell proliferation and tumor growth. What is more, DBT-2FFGYSA also serves as an effective agent to convert immunologically cold tumors to hot by inducing the immunogenic cell death of EphA2 receptor-overexpressed cancer cells and recruiting massive tumor-infiltrating T cells. This study, thus, introduces a new category of agents capable of converting cold to hot tumors by pure supramolecular self-assembly without any aid of known anticancer drugs.

Smart transformable nanomedicines for cancer therapy

Despite that great progression has been made in nanoparticulate drug delivery systems (nano-DDS), multiple drug delivery dilemmas still impair the delivery efficiency of nanomedicines. Rational design of smart transformable nano-DDS based on the in vivo drug delivery process represents a promising strategy for overcoming delivery obstacle of nano-DDS. In recent years, tremendous efforts have been devoted to developing smart transformable anticancer nanomedicines. Herein, we provide a review to outline the advances in this emerging field. First, smart size-reducible nanoparticles (NPs) for deep tumor penetration are summarized, including carrier degradation-induced, protonation-triggered and photobleaching-induced size reduction. Second, emerging transformable nanostructures for various therapeutic applications are discussed, including prolonging tumor retention, reversing drug-resistance, inhibiting tumor metastasis, preventing tumor recurrence and non-pharmaceutical therapy. Third, shell-detachable nanocarriers are introduced, focusing on chemical bonds breaking-initiated, charge repulsion-mediated and exogenous stimuli-triggered shell detachment approaches. Finally, the future perspectives and challenges of transformable nanomedicines in clinical cancer therapy are highlighted.

Supramolecular Assembled Programmable Nanomedicine As In Situ Cancer Vaccine for Cancer Immunotherapy

Using nanotechnology for improving the immunotherapy efficiency represents a major research interest in recent years. However, there are paradoxes and obstacles in using a single nanoparticle to fulfill all the requirements in the complicated immune activation processes. Herein, a supramolecular assembled programmable immune activation nanomedicine (PIAN) for sequentially finishing multiple steps after intravenous injection and eliciting robust antitumor immunity in situ is reported. The programmable nanomedicine is constructed by supramolecular assembly via host-guest interactions between poly-[(N-2-hydroxyethyl)-aspartamide]-Pt(IV)/β-cyclodextrin (PPCD), CpG/polyamidoamine-thioketal-adamantane (CpG/PAMAM-TK-Ad), and methoxy poly(ethylene glycol)-thioketal-adamantane (mPEG-TK-Ad). After intravenous injection and accumulation at the tumor site, the high level of reactive oxygen species in the tumor microenvironment promotes PIAN dissociation and the release of PPCD (mediating tumor cell killing and antigen release) and CpG/PAMAM (mediating antigen capturing and transferring to the tumor-draining lymph nodes). This results in antigen-presenting cell activation, antigen presentation, and robust antitumor immune responses. In combination with anti-PD-L1 antibody, the PIAN cures 40% of mice in a colorectal cancer model. This PIAN provides a new framework for designing programmable nanomedicine as in situ cancer vaccine for cancer immunotherapy.

Tumor Receptor-Mediated In Vivo Modulation of the Morphology, Phototherapeutic Properties, and Pharmacokinetics of Smart Nanomaterials

To be clinically efficacious, nanotherapeutic drugs need to reach disease tissues reliably and cause limited side effects to normal organs and tissues. Here, we report a proof-of-concept study on the development of a smart peptidic nanophototherapeutic agent in line with clinical requirements, which can transform its morphology from nanoparticles to nanofibrils at the tumor sites. This in vivo receptor-mediated transformation process resulted in the formation and prolonged tumor-retention of highly ordered (J-aggregate type of photosensitizer) photosensitive peptide nanofibrillar network with greatly enhanced photothermal and photodynamic properties. This strategy of "multiple daily low-intensity laser radiation after each intravenous injection of significantly low-dose of nanomaterials" demonstrated effective elimination of 4T1 orthotopic syngeneic breast cancer in mice. The technology for nanomaterial modulation based on living cell surface receptors, in this case tumor-associated α₃β₁ integrin, has great potential for clinical translation and is expected to improve the therapeutic efficacy against many cancers.

Recent advances in HER2-targeted delivery for cancer therapy

Human epidermal growth factor receptor 2 (HER2), a tyrosine kinase receptor with a molecular mass of 185kDa, is overexpressed in several cancers, such as breast, gastric, ovary, prostate, and lung. HER2 is a promising target in cancer therapy because of its crucial role in cell migration, proliferation, survival, angiogenesis, and metastasis through various intracellular signaling cascades. This receptor is an ideal target for the delivery of chemotherapeutic agents because of its accessibility to the extracellular domain. In this review, we highlight different HER2-targeting strategies and various approaches for HER2-targeted delivery systems to improve outcomes for cancer therapy.

Size-Transformable Nanostructures: From Design to Biomedical Applications

The size of nanostructures (NSs) strongly affects their chemical and physical properties and further impacts their actions in biological systems. Both small and large NSs possess respective advantages for disease theranostics, and this therefore presents a paradox when choosing NSs with suitable sizes. To overcome this challenge, size-transformable NSs have emerged as a powerful tool, as they can be manipulated to possess the merits of both types of NSs. Herein, various strategies to construct size-transformable NSs are summarized, and the recent research progress regarding their biomedical applications, particularly within the fields of cancer and bacterial theranostics, is highlighted. This review will inspire researchers to further develop various methods that can be used to construct size-transformable NSs for use in novel applications within different fields.

Acid-Activatable Transmorphic Peptide-Based Nanomaterials for Photodynamic Therapy

Inspired by the dynamic morphology control of molecular assemblies in biological systems, we have developed pH-responsive transformable peptide-based nanoparticles for photodynamic therapy (PDT) with prolonged tumor retention times. The self-assembled peptide-porphyrin nanoparticles transformed into nanofibers when exposed to the acidic tumor microenvironment, which was mainly driven by enhanced intermolecular hydrogen bond formation between the protonated molecules. The nanoparticle transformation into fibrils improved their singlet oxygen generation ability and enabled high accumulation and long-term retention at tumor sites. Strong fluorescent signals of these nanomaterials were detected in tumor tissue up to 7 days after administration. Moreover, the peptide assemblies exhibited excellent anti-tumor efficacy via PDT in vivo. This in situ fibrillar transformation strategy could be utilized to design effective stimuli-responsive biomaterials for long-term imaging and therapy.

Tumor-Activated and Metal-Organic Framework Assisted Self-Assembly of Organic Photosensitizers

Tumor accumulation and intratumoral singlet oxygen (¹O₂) generation efficiency of photosensitizers (PSs) are two essential factors that determine their photodynamic therapy (PDT) efficacies. How to maximize the PS performance at the tumor site is of great research interest. Herein, we report a metal-organic framework (ZIF-8, ZIF = zeolitic imidazolate framework) assisted in vivo self-assembly nanoplatform, ZIF-8-PMMA-S-S-mPEG, as an effective tool for organic PS payloads to achieve efficient PDT. Using an organic PS with aggregation-induced emission as an example, under intratumoral bioreduction, PS-loaded ZIF-8-PMMA-S-S-mPEG (PS@ZIF-8-PMMA-S-S-mPEG) was self-assembled into large ordered hydrophobic clusters, which greatly enhance tumor retention and accumulation of the PS. Moreover, hydrophobic ZIF-8 assemblies greatly isolate the loaded PSs from water and improve O₂ transport for the PSs to effectively produce ¹O₂ inside tumors under light irradiation. The organic PS is therefore endowed with optimal tumor accumulation and intratumoral ¹O₂ production, demonstrating the effectiveness of the developed self-assembly strategy in PDT application.

Multifunctional peptides for tumor therapy

Controlled nano-systems for drug delivery are designed to deliver therapeutical drugs to desirable sites on demand. Due to the diverse physiological functions of peptides, it is reasonable to introduce peptides into anti-tumor nano-system. The integration of peptides into nanomaterials has complementary advantages, which not only avoids the rapid degradation of peptides in vivo, but also improves the intelligence and functionality of the nano-system. We summarized the functional peptides with targeting and stimulus-responsive properties, and the present review outlined the most relevant and recent developed peptide-based multifunctional nanomaterials for tumor therapy.

Peptides, proteins and nanotechnology: a promising synergy for breast cancer targeting and treatment

INTRODUCTION

The use of nanoparticles for breast cancer targeting and treatment has become a reality. They are safe and possess interesting peculiarities such as the unspecific accumulation into the tumor site and the possibility to activate controlled drug release as compared to free drugs. However, there are still many areas of improvement which can certainly be addressed with the use of peptide-based elements.

AREAS COVERED

The article reviews different preclinical strategies employing peptides and proteins in combination with nanoparticles for breast cancer targeting and treatment as well as peptide and protein-targeted encapsulated drugs, and it lists the current clinical status of therapies using peptides and proteins for breast cancer.

EXPERT OPINION

The conjugation of protein and peptides can improve tumor homing of nanoparticles, increase cellular penetration and attack specific drivers and vulnerabilities of the breast cancer cell to promote tumor cytotoxicity while reducing secondary effects in healthy tissues. Examples are the use of antibodies, arginylglycylaspartic acid (RGD) peptides, membrane disruptive peptides, interference peptides, and peptide vaccines. Although their implementation in the clinic has been relatively slow up to now, we anticipate great progress in the field which will translate into more efficacious and selective nanotherapies for breast cancer.

Tumor microenvironment-oriented adaptive nanodrugs based on peptide self-assembly

The aberrant metabolism of tumor cells creates an inimitable microenvironment featuring acidic pH, high glutathione (GSH) levels, and overexpression of certain enzymes, which benefits the overwhelming progress of a tumor. Peptide self-assembly, emerging as a biofriendly and versatile fabrication strategy, harnesses multiple noncovalent interactions to obtain a variety of nanostructures tailored on demand. Orchestrating the reversible nature of noncovalent interactions and abnormal physiological parameters in the tumor microenvironment enables peptide-based nanodrugs to be targetable or switchable, thereby improving the drugs' bioavailability and optimizing the treatment outcome. This review will focus on peptide-modulated self-assembly of photosensitizers, chemotherapeutic drugs, immunoactive agents for tumor microenvironment-oriented adaptive phototherapy, chemotherapy, immunotherapy and combinatorial therapy. We will emphasize the building block design, the intermolecular interaction principle, adaptive structural transformation in the tumor microenvironment and corresponding therapeutic efficacy, and aim to elucidate the critical role of peptide-modulated, tumor microenvironment-oriented adaptive assemblies in improving the therapeutic index. Challenges and opportunities will be covered as well to advance the development and clinical application of tumor therapies based on peptide self-assembly materials and techniques.

Supramolecular Self-Assembled Nanostructures for Cancer Immunotherapy

Functional materials and nanostructures have been widely used for enhancing the therapeutic potency and safety of current cancer immunotherapy. While profound nanostructures have been developed to participate in the development of cancer immunotherapy, the construction of intricate nanostructures with easy fabrication and functionalization properties to satisfy the diversified requirements in cancer immunotherapy are highly required. Hierarchical self-assembly using supramolecular interactions to manufacture organized architectures at multiple length scales represents an interesting and promising avenue for sophisticated nanostructure construction. In this mini-review, we will outline the recent progress made in the development of supramolecular self-assembled nanostructures for cancer immunotherapy, with special focus on the supramolecular interactions including supramolecular peptide assembly, supramolecular DNA assembly, lipid hydrophobic assembly, host-guest assembly, and biomolecular recognition assembly.

Shedding Light on Extracellular Vesicle Biogenesis and Bioengineering

Extracellular vesicles (EVs) are biocompatible, nano-sized secreted vesicles containing many types of biomolecules, including proteins, RNAs, DNAs, lipids, and metabolites. Their low immunogenicity and ability to functionally modify recipient cells by transferring diverse bioactive constituents make them an excellent candidate for a next-generation drug delivery system. Here, the recent advances in EV biology and emerging strategies of EV bioengineering are summarized, and the prospects for clinical translation of bioengineered EVs and the challenges to be overcome are discussed.