Targeted redox-responsive peptide for arterial chemoembolization therapy of orthotropic hepatocellular carcinoma

OBJECTIVE

Transcatheter Arterial Chemoembolization (TACE) is the first choice for the treatment of advanced-stage hepatocellular carcinoma (HCC). However, TACE suffers from a lack of specificity and rapid drug release. Herein, a targeted redox-responsive peptide (TRRP) was synthesized and used as a carrier of doxorubicin (DOX) to enhance the efficacy of TACE through tumor cells targeting and controlled drug release.

METHODS

TRRP has a high loading capacity of DOX and a sensitive drug release behavior at high glutathione (GSH) concentration. Moreover, TRRP could bind to the transferrin receptor on the surface of tumor cells, which enhanced the efficacy of TACE and reduced side effects of TACE. TACE with TRRP@DOX dispersed in lipiodol shows an enhanced therapeutic outcome compared to the treatment with DOX + lipiodol emulsion in orthotopic rat HCC models.

RESULTS

TRRP has a high loading capacity of DOX and a sensitive drug release behavior at GSH concentration. Moreover, TRRP could bind to the transferrin receptor on the surface of tumor cells, which enhanced the efficacy of TACE and reduced side effects of TACE. TACE with TRRP@DOX dispersed in lipiodol shows an enhanced therapeutic outcome compared to the treatment with DOX + lipiodol emulsion in orthotopic rat HCC models.

CONCLUSIONS

This study demonstrated that TRRP was a promising therapeutic agent for enhancing TACE therapy for HCC treatment.

Dual-targeted and dual-sensitive self-assembled protein nanocarrier delivering hVEGI-192 for triple-negative breast cancer

Breast cancer is a highly prevalent malignancy worldwide among women with an increasing incidence in recent years. Triple-negative breast cancer (TNBC), a specific type of breast cancer, occurs primarily in young women and exhibits large tumor size, high clinical stage, and extremely poor prognosis with a high rate of lymph node, liver, and lung metastases. TNBC is insensitive to endocrine therapy and trastuzumab treatment, and there is an urgent need for effective therapeutics and treatment guidelines. However, investigations into antiangiogenic agents for the treatment of TNBC are ongoing. In this study, we successfully engineered a self-assembled protein nanocarrier TfRBP9-hVEGI-192-ELP fusion protein (TVEFP) to deliver the therapeutic protein, human vascular endothelial growth inhibitor (hVEGI-192). This was found to be effective in inhibiting tumor angiogenesis in vivo. The protein nanocarrier effectively inhibited the progression of TNBC in vivo and showed the behavior of self-assembly, thermoresponsiveness, enzyme stimulation-responsiveness, tumor-targeting, biocompatibility, and biodegradability. Near-infrared imaging studies showed that fluorescent dye-stained TVEFP effectively aggregated at the tumor site. The TVEFP nanocarrier significantly expands the application of the therapeutic protein hVEGI-192 and improves the imaging and biotherapeutic effects in TNBC, chiefly based on anti-angiogenesis effects.

Transferrin receptor-mediated liposomal drug delivery: recent trends in targeted therapy of cancer

INTRODUCTION

Compared to normal cells, malignant cancer cells require more iron for their growth and rapid proliferation, which can be supplied by a high expression level of transferrin receptor (TfR). It is well known that the expression of TfR on the tumor cells is considerably higher than that of normal cells, which makes TfR an attractive target in cancer therapy.

AREAS COVERED

In this review, the primary focus is on the role of TfR as a valuable tool for cancer-targeted drug delivery, followed by the full coverage of available TfR ligands and their conjugation chemistry to the surface of liposomes. Finally, the most recent studies investigating the potential of TfR-targeted liposomes as promising drug delivery vehicles to different cancer cells are highlighted with emphasis on their improvement possibilities to become a part of future cancer medicines.

EXPERT OPINION

Liposomes as a valuable class of nanocarriers have gained much attention toward cancer therapy. From all the studies that have exploited the therapeutic and diagnostic potential of TfR on cancer cells, it can be realized that the systematic assessment of TfR ligands applied for liposomal targeted delivery has yet to be entirely accomplished.

Peptides and pseudopeptide ligands: a powerful toolbox for the affinity purification of current and next-generation biotherapeutics

Following the consolidation of therapeutic proteins in the fight against cancer, autoimmune, and neurodegenerative diseases, recent advancements in biochemistry and biotechnology have introduced a host of next-generation biotherapeutics, such as CRISPR-Cas nucleases, stem and car-T cells, and viral vectors for gene therapy. With these drugs entering the clinical pipeline, a new challenge lies ahead: how to manufacture large quantities of high-purity biotherapeutics that meet the growing demand by clinics and biotech companies worldwide. The protein ligands employed by the industry are inadequate to confront this challenge: while featuring high binding affinity and selectivity, these ligands require laborious engineering and expensive manufacturing, are prone to biochemical degradation, and pose safety concerns related to their bacterial origin. Peptides and pseudopeptides make excellent candidates to form a new cohort of ligands for the purification of next-generation biotherapeutics. Peptide-based ligands feature excellent target biorecognition, low or no toxicity and immunogenicity, and can be manufactured affordably at large scale. This work presents a comprehensive and systematic review of the literature on peptide-based ligands and their use in the affinity purification of established and upcoming biological drugs. A comparative analysis is first presented on peptide engineering principles, the development of ligands targeting different biomolecular targets, and the promises and challenges connected to the industrial implementation of peptide ligands. The reviewed literature is organized in (i) conventional (α-)peptides targeting antibodies and other therapeutic proteins, gene therapy products, and therapeutic cells; (ii) cyclic peptides and pseudo-peptides for protein purification and capture of viral and bacterial pathogens; and (iii) the forefront of peptide mimetics, such as β-/γ-peptides, peptoids, foldamers, and stimuli-responsive peptides for advanced processing of biologics.

Design, synthesis, and in vitro antitumor activity of a transferrin receptor-targeted peptide-doxorubicin conjugate

In this study, a peptide-drug conjugate was designed and synthesized by connecting a transferrin receptor (TfR)-targeted binding peptide analog BP9a (CAHLHNRS) with doxorubicin (DOX) through N-succinimidyl-3-maleimidopropionate (SMP) as the cross-linker. Confocal laser scanning microscopy results indicated that free DOX mainly accumulated in the nuclei of both TfR overexpressed HepG2 hepatoma cells and L-O2 normal liver cells expressing low level of TfR; most of the BP9a-DOX conjugate displayed cytoplasmic location, and its cellular uptake by HepG2 cells was obviously reduced by TfR blockage test. Nevertheless, the cellular uptake of this conjugate by L-O2 cells was much less than that of free DOX. Meanwhile, the BP9a-DOX conjugate exhibited lower in vitro antiproliferative activity against HepG2 cells than free DOX, but its cytotoxic effect on L-O2 cells was decreased compared with that of free DOX. These results suggest that BP9a could be applied as a potential TfR-targeted peptide vector for selective drug delivery.

Selection and identification of transferrin receptor-specific peptides as recognition probes for cancer cells

Since the transferrin receptor (CD71 or TFRC) is known to be highly expressed in numerous cancers, CD71 has become an attractive target in cancer research. Acquiring specific molecular probes for CD71, such as small molecular ligands, aptamers, peptides, or antibodies, is of great importance for cancer cell recognition and capture. In this work, we chose CD71 as the target for phage display, and after four rounds of positive selection and one round of negative selection, the specific phage library was enriched. After verification and sequence analysis, six peptides were identified to be able to bind to CD71 with high specificity. The specific recognition of the CD71-positive cells was confirmed by flow cytometry and confocal microscopy. Competition experiments demonstrated that peptide Y1 and transferrin (TF) were bound to distinct sites on CD71, indicating that peptide Y1 could replace TF as a potential probe for cell imaging and drug delivery, thus avoiding competition by endogenous TF and side effects. Graphical abstract Six peptides were successfully isolated using in vitro biopanning against CD71 with high specificity and affinity. Peptides Y1 and Y2 would be powerful tools in biosensors and biomedicine due to their unique properties.

Recombinant Nogo-66 via soluble expression with SUMO fusion in Escherichia coli inhibits neurite outgrowth in vitro

Nogo-66, a hydrophilic loop of 66 amino acids flank two hydrophobic domains of the Nogo-A C terminus, interacts with the Nogo-66 receptor (NgR) to exert numerous functions in the central nervous system (CNS). Nogo-66 has important roles in aspects of neuronal development, including cell migration, axon guidance, fasciculation, and dendritic branching, and in aspects of CNS plasticity, including oligodendrocyte differentiation and myelination. Here, the small ubiquitin-related modifier (SUMO) was fused to the target gene, Nogo-66, and the construct was expressed in Escherichia coli (E. coli). Under the optimal fermentation conditions, the soluble expression level of the fusion protein was 33 % of the total supernatant protein. After cleaving the fusion proteins with SUMO protease and purifying them by Ni-NTA affinity chromatography, the yield and purity of recombinant Nogo-66 obtained by 10-L scale fermentation were 23 ± 1.5 mg/L and greater than 93 %, respectively. The authenticity of the recombinant Nogo-66 was confirmed by an electrospray ionization-mass spectrometry analysis. The functional analyses indicated that the recombinant Nogo-66 was capable of binding the NgR specifically. The immunofluorescence results showed that the recombinant Nogo-66 could significantly inhibit neurite outgrowth of rat pheochromocytoma (PC12) cells stimulated by nerve growth factor and cerebellar granule cells (CGCs). Furthermore, Nogo-66 inhibited neurite outgrowth by increasing the level of phosphorylated Rho-associated coiled-coil-containing protein kinase 2 (ROCK2), collapsin response mediator protein 2 (CRMP2), and myosin light chain (MLC). This study provided a feasible and convenient production method for generating sufficient recombinant Nogo-66 for experimental and clinical applications.