Self-assembling protein nanocarrier for selective delivery of cytotoxic polypeptides to CXCR4+ head and neck squamous cell carcinoma tumors

Targeting the chemokine receptor CXCR4 for cancer therapies

The C-X-C chemokine receptor type 4 (CXCR4) has emerged as a key molecular biomarker for cancer therapies due to its critical role in tumor progression and metastases by displaying a stem cells phenotype. Its overexpression has been observed in more than 20 types of cancers, including solid tumors and hematological malignancies, and it is often associated with tumor aggressiveness and poor prognosis. Being initially recognized as a co-receptor involved in HIV infection, numerous CXCR4-targeting ligands and antagonists, including small molecules, peptides and biologics have been identified over the past decades. While only few of them have been used in the context of cancer therapies, recent biotechnological advancements using CXCR4 as a molecular target are showing significant potential to revolutionize future cancer therapies. Therefore, this review highlights the biotechnological innovations developed for cancer therapy and diagnosis by targeting the chemokine receptor CXCR4. It also discusses future perspectives on emerging therapeutic strategies, ranging from the use of small molecule inhibitors that block receptor signaling to cutting-edge nanocarriers designed for the targeted delivery of innovative drugs and proteins into cancer stem cells, aiming at cell-selective precision nanomedicines.

A Targeted Nanotoxin Inhibits Colorectal Cancer Growth Through Local Tumor Pyroptosis and Eosinophil Infiltration and Degranulation

Background

Colorectal cancer (CRC) has traditionally been treated with genotoxic chemotherapy to activate pro-apoptotic proteins to induce anticancer effects. However, cancer cells develop resistance to apoptosis, which leads to recurrence and poor prognosis. Moreover, this kind of therapy has been shown to be highly toxic to healthy tissues and, therefore, to patients. To overcome this issue, we developed a self-assembly tumor-targeted nanoparticle, T22-DITOX-H6, that incorporates the T22 peptide (a CXCR4 ligand) to selectively target cells overexpressing CXCR4, fused to the catalytic domain of diphtheria toxin, that exhibits a potent cytotoxic effect on these CXCR4+ cancer cells that exhibits potent cytotoxic effects on CXCR4-overexpressing cancer cells through the activation of pyroptosis, an immunogenic type of cell death.

Methods

Colorectal CXCR4-expressing tumor cells (CT26-CXCR4+) were implanted subcutaneously into immunocompetent mice to study the effects of T22-DITOX-H6 treatment on tumor growth, cell death and innate immune cell recruitment to the tumor.

Results

Here, we demonstrated that the T22-DITOX-H6 nanoparticle selectively activated pyroptosis, an immunogenic cell death that differs from apoptosis, leading to cell death in CXCR4-expressing cells, without affecting the viability of CXCR4-lacking cells. In addition, the nanoparticle administered to tumor-bearing mice induced a local antitumor effect due to the selective activation of pyroptosis in CXCR4+ targeted cancer cells. Biochemical analysis of plasma and histological analysis of non-tumor tissues revealed no differences between the groups. Remarkably, pyroptosis activation stimulates eosinophil infiltration into the tumor microenvironment, an effect recently reported to have an anti-tumorigenic function.

Conclusion

These results highlight the dual role of CXCR4-targeted cytotoxic nanoparticle in eliminating cancer cells and boosting the self-immune response without compromising healthy organs.

New advances in the therapeutic strategy of head and neck squamous cell carcinoma: A review of latest therapies and cutting-edge research

Head and neck squamous cell carcinoma (HNSCC) is a common and aggressive malignancy with a poor prognosis, particularly when diagnosed at advanced stages. Despite progress in surgical, chemotherapeutic, and radiotherapeutic interventions, the five-year survival rate remains low due to high rates of recurrence and therapeutic resistance. This review explores recent advances in therapeutic strategies for HNSCC, focusing on targeted therapies, immunotherapy, and innovative drug delivery systems. Targeted therapies, such as EGFR inhibitors and PI3K/AKT/mTOR pathway inhibitors, offer promising options for overcoming HNSCC, though resistance challenges persist. Emerging treatments, including dual-target inhibitors and personalized therapeutic approaches, show potential in addressing these limitations. Immunotherapy, particularly PD-1/PD-L1 blockade, has achieved positive outcomes in a subset of patients, though overall response rates remain modest. Strategies aimed at enhancing immune responses, such as combination therapies and nanotechnology-based drug delivery systems, are actively being investigated to improve efficacy. This review also underscores the critical role of the tumor microenvironment and epithelial-mesenchymal transition (EMT) in HNSCC progression and therapeutic resistance. Novel approaches, including smart drug delivery systems utilizing nanotechnology and immune modulation, are opening new avenues for more personalized and effective treatments. Ongoing interdisciplinary research into molecular targets and advanced drug delivery techniques holds great promise for significantly improving patient outcomes in HNSCC.

Revolutionizing head and neck squamous cell carcinoma treatment with nanomedicine in the era of immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is a prevalent malignant tumor globally. Despite advancements in treatment methods, the overall survival rate remains low due to limitations such as poor targeting and low bioavailability, which result in the limited efficacy of traditional drug therapies. Nanomedicine is considered to be a promising strategy in tumor therapy, offering the potential for maximal anti-tumor effects. Nanocarriers can overcome biological barriers, enhance drug delivery efficiency to targeted sites, and minimize damage to normal tissues. Currently, various nano-carriers for drug delivery have been developed to construct new nanomedicine. This review aims to provide an overview of the current status of HNSCC treatment and the necessity of nanomedicine in improving treatment outcomes. Moreover, it delves into the research progress of nanomedicine in HNSCC treatment, with a focus on enhancing radiation sensitivity, improving the efficacy of tumor immunotherapy, effectively delivering chemotherapy drugs, and utilizing small molecule inhibitors. Finally, this article discussed the challenges and prospects of applying nanomedicine in cancer treatment.

Cancer immunogenic cell death via pyroptosis with CXCR4-targeted nanotoxins in hepatocellular carcinoma

Introduction

Cytotoxic agents have shown limited benefits in hepatocellular carcinoma (HCC), mediated in part by the lack of targeting. As cell-penetrating peptides (CPPs) are capable of delivering various biologically active molecules into cells, including protein, peptides, small chemo-drugs, and nucleic acid with or without targeting, we developed T22-PE24, a CXCR4-targeted self-assembling cytotoxic nanotoxin, to effectively induce HCC pyroptosis.

Methods

T22 incorporating enhanced green fluorescent protein (EGFP) or PE24 was purified from DE3 bacterial cells and characterized using transmission electron microscopy, the Zetasizer Nano®, and SEC-HPLC. The internalization effect of T22-EGFP was detected by flow cytometry system (FCS) in CXCR4+/LM3(CXCR4-) HCC cells. The CCK8, lactate dehydrogenase (LDH) release, Western blot, and nude mice HCC models were used to estimate the cell viability of T22-PE24. The complete-immunity HCC tumor-bearing mice model was used to assess the immune response of T22-PE24.

Results

The round shape under transmission electron microscopy, 49.4 nm hydrodynamic diameter, and -33.33 mV zeta potential indicated that T22-PE24 self-assembled into nanoparticles. T22 incorporating EGFP selectively internalized in CXCR4+ HCC cells and showed no accumulation in CXCR4-knockout HCC cells. The T22-PE24 nanotoxin induced HCC pyroptosis via the caspase-3/GSDME signaling pathway and suppressed tumor growth in the absence of histological alterations in normal organs. Using the complete-immunity HCC tumor-bearing mice model, we found that T22-PE24 nanotoxin effectively induces the global reprogramming of cell components of the immune tumor microenvironment, leading to enhanced antitumor effects compared to those observed in immunodeficient mice.

Conclusion

Our findings demonstrate the activation of the innate immune response in HCC by inducing pyroptosis with T22-PE24 nanotoxin treatment and support an implementation of this strategy for HCC treatment.

CXCR4 Expression as a Prognostic Biomarker in Soft Tissue Sarcomas

Poor long-term survival in localized high-risk soft tissue sarcomas (STSs) of the extremities and trunk highlights the need to identify new prognostic factors. CXCR4 is a chemokine receptor involved in tumor progression, angiogenesis, and metastasis. The aim of this study was to evaluate the association between CXCR4 expression in tumor tissue and survival in STSs patients treated with neoadjuvant therapy. CXCR4 expression was retrospectively determined by immunohistochemical analysis in serial specimens including initial biopsies, tumors post-neoadjuvant treatment, and tumors after relapse. We found that a positive cytoplasmatic expression of CXCR4 in tumors after neoadjuvant treatment was a predictor of poor recurrence-free survival (RFS) (p = 0.003) and overall survival (p = 0.019) in synovial sarcomas. We also found that positive nuclear CXCR4 expression in the initial biopsies was associated with poor RFS (p = 0.022) in undifferentiated pleomorphic sarcomas. In conclusion, our study adds to the evidence that CXCR4 expression in tumor tissue is a promising prognostic factor for STSs.

Protein-based Nanoparticles: From Drug Delivery to Imaging, Nanocatalysis and Protein Therapy

Proteins and enzymes are versatile biomaterials for a wide range of medical applications due to their high specificity for receptors and substrates, high degradability, low toxicity, and overall good biocompatibility. Protein nanoparticles are formed by the arrangement of several native or modified proteins into nanometer-sized assemblies. In this review, we will focus on artificial nanoparticle systems, where proteins are the main structural element and not just an encapsulated payload. While under natural conditions, only certain proteins form defined aggregates and nanoparticles, chemical modifications or a change in the physical environment can further extend the pool of available building blocks. This allows the assembly of many globular proteins and even enzymes. These advances in preparation methods led to the emergence of new generations of nanosystems that extend beyond transport vehicles to diverse applications, from multifunctional drug delivery to imaging, nanocatalysis and protein therapy.

Lymphocyte infiltration and antitumoral effect promoted by cytotoxic inflammatory proteins formulated as self-assembling, protein-only nanoparticles

Two human proteins involved in the inflammatory cell death, namely Gasdermin D (GSDMD) and the Mixed Lineage Kinase Domain-Like (MLKL) protein have been engineered to accommodate an efficient ligand of the tumoral cell marker CXCR4, and a set of additional peptide agents that allow their spontaneous self-assembling. Upon production in bacterial cells and further purification, both proteins organized as stable nanoparticles of 46 and 54 nm respectively, that show, in this form, a moderate but dose-dependent cytotoxicity in cell culture. In vivo, and when administered in mouse models of colorectal cancer through repeated doses, the nanoscale forms of tumor-targeted GSDMD and, at a lesser extent, of MLKL promoted CD8⁺ and CD20⁺ lymphocyte infiltration in the tumor and an important reduction of tumor size, in absence of systemic toxicity. The potential of these novel pharmacological agents as anticancer drugs is discussed in the context of synergistic approaches to more effective cancer treatments.

Recombinant Proteins for Assembling as Nano- and Micro-Scale Materials for Drug Delivery: A Host Comparative Overview

By following simple protein engineering steps, recombinant proteins with promising applications in the field of drug delivery can be assembled in the form of functional materials of increasing complexity, either as nanoparticles or nanoparticle-leaking secretory microparticles. Among the suitable strategies for protein assembly, the use of histidine-rich tags in combination with coordinating divalent cations allows the construction of both categories of material out of pure polypeptide samples. Such molecular crosslinking results in chemically homogeneous protein particles with a defined composition, a fact that offers soft regulatory routes towards clinical applications for nanostructured protein-only drugs or for protein-based drug vehicles. Successes in the fabrication and final performance of these materials are expected, irrespective of the protein source. However, this fact has not yet been fully explored and confirmed. By taking the antigenic RBD domain of the SARS-CoV-2 spike glycoprotein as a model building block, we investigated the production of nanoparticles and secretory microparticles out of the versions of recombinant RBD produced by bacteria (Escherichia coli), insect cells (Sf9), and two different mammalian cell lines (namely HEK 293F and Expi293F). Although both functional nanoparticles and secretory microparticles were effectively generated in all cases, the technological and biological idiosyncrasy of each type of cell factory impacted the biophysical properties of the products. Therefore, the selection of a protein biofabrication platform is not irrelevant but instead is a significant factor in the upstream pipeline of protein assembly into supramolecular, complex, and functional materials.

A self-assembling CXCR4-targeted pyroptosis nanotoxin for melanoma therapy

While immunotherapy has emerged as a promising strategy to treat melanoma, the limited availability of immunotherapeutic agents in tumors due to the immunosuppressive tumor microenvironment dampens its efficacy. Pyroptosis is a gasdermin-mediated programmed necrosis that triggers the inflammatory tumor microenvironment and enhances the efficacy of tumor immunotherapy. Here, we prove that the CXCR4 antagonist T22 peptide specially targeted and became internalized into CXCR4⁺ melanoma cells. Then we report a self-assembling nanotoxin that can be used to spatiotemporally target CXCR4-expression melanoma cells and enable tunable cellular pyroptosis. Specific activation of caspase 3 signal transduction triggers gasdermin-E-mediated pyroptosis. This nanotoxin induces pyroptotic cell death resulting in enhanced antitumor efficacy and minimized systemic side effects toward melanoma in vivo. This study offers new insights into how to engineer nanotoxins with tunable pyroptosis activity through specifically targeting CXCR4 for biomedical applications.

Peptide-assembled nanoparticles targeting tumor cells and tumor microenvironment for cancer therapy

Tumor cells and corrupt stromal cells in the tumor microenvironment usually overexpress cancer-specific markers that are absent or barely detectable in normal cells, providing available targets for inhibiting the occurrence and development of cancers. It is noticeable that therapeutic peptides are emerging in cancer therapies and playing more and more important roles. Moreover, the peptides can be self-assembled and/or incorporated with polymeric molecules to form nanoparticles via non-covalent bond, which have presented appealing as well as enhanced capacities of recognizing targeted cells, responding to microenvironments, mediating internalization, and achieving therapeutic effects. In this review, we will introduce the peptide-based nanoparticles and their application advances in targeting tumor cells and stromal cells, including suppressive immune cells, fibrosis-related cells, and angiogenic vascular cells, for cancer therapy.

Cancer Immunotherapy and Delivery System: An Update

With an understanding of immunity in the tumor microenvironment, immunotherapy turns out to be a powerful tool in the clinic to treat many cancers. The strategies applied in cancer immunotherapy mainly include blockade of immune checkpoints, adoptive transfer of engineered cells, such as T cells, natural killer cells, and macrophages, cytokine therapy, cancer vaccines, and oncolytic virotherapy. Many factors, such as product price, off-target side effects, immunosuppressive tumor microenvironment, and cancer cell heterogeneity, affect the treatment efficacy of immunotherapies against cancers. In addition, some treatments, such as chimeric antigen receptor (CAR) T cell therapy, are more effective in treating patients with lymphoma, leukemia, and multiple myeloma rather than solid tumors. To improve the efficacy of targeted immunotherapy and reduce off-target effects, delivery systems for immunotherapies have been developed in past decades using tools such as nanoparticles, hydrogel matrix, and implantable scaffolds. This review first summarizes the currently common immunotherapies and their limitations. It then synopsizes the relative delivery systems that can be applied to improve treatment efficacy and minimize side effects. The challenges, frontiers, and prospects for applying these delivery systems in cancer immunotherapy are also discussed. Finally, the application of these approaches in clinical trials is reviewed.

Novel Endometrial Cancer Models Using Sensitive Metastasis Tracing for CXCR4-Targeted Therapy in Advanced Disease

Advanced endometrial cancer (EC) lacks therapy, thus, there is a need for novel treatment targets. CXCR4 overexpression is associated with a poor prognosis in several cancers, whereas its inhibition prevents metastases. We assessed CXCR4 expression in EC in women by using IHC. Orthotopic models were generated with transendometrial implantation of CXCR4-transduced EC cells. After in vitro evaluation of the CXCR4-targeted T22-GFP-H6 nanocarrier, subcutaneous EC models were used to study its uptake in tumor and normal organs. Of the women, 91% overexpressed CXCR4, making them candidates for CXCR4-targeted therapies. Thus, we developed CXCR4⁺ EC mouse models to improve metastagenesis compared to current models and to use them to develop novel CXCR4-targeted therapies for unresponsive EC. It showed enhanced dissemination, especially in the lungs and liver, and displayed 100% metastasis penetrance at all clinically relevant sites with anti-hVimentin IHC, improving detection sensitivity. Regarding the CXCR4-targeted nanocarrier, 60% accumulated in the SC tumor; therefore, selectively targeting CXCR4⁺ cancer cells, without toxicity in non-tumor organs. Our CXCR4⁺ EC models will allow testing of novel CXCR4-targeted drugs and development of nanomedicines derived from T22-GFP-H6 to deliver drugs to CXCR4⁺ cells in advanced EC. This novel approach provides a therapeutic option for women with metastatic, high risk or recurrent EC that have a dismal prognosis and lack effective therapies.

A Novel CXCR4-Targeted Diphtheria Toxin Nanoparticle Inhibits Invasion and Metastatic Dissemination in a Head and Neck Squamous Cell Carcinoma Mouse Model

Loco-regional recurrences and metastasis represent the leading causes of death in head and neck squamous cell carcinoma (HNSCC) patients, highlighting the need for novel therapies. Chemokine receptor 4 (CXCR4) has been related to loco-regional and distant recurrence and worse patient prognosis. In this regard, we developed a novel protein nanoparticle, T22-DITOX-H6, aiming to selectively deliver the diphtheria toxin cytotoxic domain to CXCR4⁺ HNSCC cells. The antimetastatic effect of T22-DITOX-H6 was evaluated in vivo in an orthotopic mouse model. IVIS imaging system was utilized to assess the metastatic dissemination in the mouse model. Immunohistochemistry and histopathological analyses were used to study the CXCR4 expression in the cancer cells, to evaluate the effect of the nanotoxin treatment, and its potential off-target toxicity. In this study, we report that CXCR4⁺ cancer cells were present in the invasive tumor front in an orthotopic mouse model. Upon repeated T22-DITOX-H6 administration, the number of CXCR4⁺ cancer cells was significantly reduced. Similarly, nanotoxin treatment effectively blocked regional and distant metastatic dissemination in the absence of systemic toxicity in the metastatic HNSCC mouse model. The repeated administration of T22-DITOX-H6 clearly abrogates tumor invasiveness and metastatic dissemination without inducing any off-target toxicity. Thus, T22-DITOX-H6 holds great promise for the treatment of CXCR4⁺ HNSCC patients presenting worse prognosis.

CXCR4-targeted nanotoxins induce GSDME-dependent pyroptosis in head and neck squamous cell carcinoma

BACKGROUND

Therapy resistance, which leads to the development of loco-regional relapses and distant metastases after treatment, constitutes one of the major problems that head and neck squamous cell carcinoma (HNSCC) patients currently face. Thus, novel therapeutic strategies are urgently needed. Targeted drug delivery to the chemokine receptor 4 (CXCR4) represents a promising approach for HNSCC management. In this context, we have developed the self-assembling protein nanotoxins T22-PE24-H6 and T22-DITOX-H6, which incorporate the de-immunized catalytic domain of Pseudomonas aeruginosa (PE24) exotoxin A and the diphtheria exotoxin (DITOX) domain, respectively. Both nanotoxins contain the T22 peptide ligand to specifically target CXCR4-overexpressing HNSCC cells. In this study, we evaluate the potential use of T22-PE24-H6 and T22-DITOX-H6 nanotoxins for the treatment of HNSCC.

METHODS

T22-PE24-H6 and T22-DITOX-H6 CXCR4-dependent cytotoxic effect was evaluated in vitro in two different HNSCC cell lines. Both nanotoxins cell death mechanisms were assessed in HNSCC cell lines by phase-contrast microscopy, AnnexinV/ propidium iodide (PI) staining, lactate dehydrogenase (LDH) release assays, and western blotting. Nanotoxins antitumor effect in vivo was studied in a CXCR4+ HNSCC subcutaneous mouse model. Immunohistochemistry, histopathology, and toxicity analyses were used to evaluate both nanotoxins antitumor effect and possible treatment toxicity. GSMDE and CXCR4 expression in HNSCC patient tumor samples was also assessed by immunohistochemical staining.

RESULTS

First, we found that both nanotoxins exhibit a potent CXCR4-dependent cytotoxic effect in vitro. Importantly, nanotoxin treatment triggered caspase-3/Gasdermin E (GSDME)-mediated pyroptosis. The activation of this alternative cell death pathway that differs from traditional apoptosis, becomes a promising strategy to bypass therapy resistance. In addition, T22-PE24-H6 and T22-DITOX-H6 displayed a potent antitumor effect in the absence of systemic toxicity in a CXCR4+ subcutaneous HNSCC mouse model. Lastly, GSDME was found to be overexpressed in tumor tissue from HNSCC patients, highlighting the relevance of this strategy.

CONCLUSIONS

Altogether, our results show that T22-PE24-H6 and T22-DITOX-H6 represent a promising therapy for HNSCC patients. Remarkably, this is the first study showing that both nanotoxins are capable of activating caspase-3/GSDME-dependent pyroptosis, opening a novel avenue for HNSCC treatment.

Antibacterial Activity of T22, a Specific Peptidic Ligand of the Tumoral Marker CXCR4

CXCR4 is a cytokine receptor used by HIV during cell attachment and infection. Overexpressed in the cancer stem cells of more than 20 human neoplasias, CXCR4 is a convenient antitumoral drug target. T22 is a polyphemusin-derived peptide and an effective CXCR4 ligand. Its highly selective CXCR4 binding can be exploited as an agent for the cell-targeted delivery and internalization of associated antitumor drugs. Sharing chemical and structural traits with antimicrobial peptides (AMPs), the capability of T22 as an antibacterial agent remains unexplored. Here, we have detected T22-associated antimicrobial activity and biofilm formation inhibition over Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, in a spectrum broader than the reference AMP GWH1. In contrast to GWH1, T22 shows neither cytotoxicity over mammalian cells nor hemolytic activity and is active when displayed on protein-only nanoparticles through genetic fusion. Under the pushing need for novel antimicrobial agents, the discovery of T22 as an AMP is particularly appealing, not only as its mere addition to the expanding catalogue of antibacterial drugs. The recognized clinical uses of T22 might allow its combined and multivalent application in complex clinical conditions, such as colorectal cancer, that might benefit from the synchronous destruction of cancer stem cells and local bacterial biofilms.