The transferrin receptor and the targeted delivery of therapeutic agents against cancer

Micelle-like nanoparticles as siRNA and miRNA carriers for cancer therapy

Gene therapy has emerged as an alternative in the treatment of cancer, particularly in cases of resistance to chemo and radiotherapy. Different approaches to deliver genetic material to tumor tissues have been proposed, including the use of small non-coding RNAs due to their multiple mechanisms of action. However, such promise has shown limits in in vivo application related to RNA's biological instability and stimulation of immunity, urging the development of systems able to overcome those barriers. In this review, we discuss the use of RNA interference in cancer therapy with special attention to the role of siRNA and miRNA and to the challenges of their delivery in vivo. We introduce a promising class of drug delivery system known as micelle-like nanoparticles and explore their synthesis and advantages for gene therapy as well as the recent findings in in vitro, in vivo and clinical studies.

Isolation of transferrin by imprinted nanoparticles with magnetic deep eutectic solvents as monomer

Transferrin (TrF) is a very important human body glycoprotein and a clinical biomarker which controls the body's iron ion channels and iron ion balance. Any change in TrF concentration and isoform also reflects the emergence of some diseases. In this work, we prepared magnetic molecularly imprinted nanoparticles (deep eutectic solvent-molecular imprinting polymers [DES-MIPs]) with a deep eutectic solvent (DES) as a functional monomer to separate TrF in human serum. The DES dosage for MIP, pH value, and time for adsorption have been optimized, and these materials show special adsorption properties for TrF. The maximum adsorption capacity (Q_max) and dissociation constant K_L of the MIP by the Langmuir adsorption curve (R² = 0.9949) were 37.5 mg/g and 0.015 g/L, respectively. The imprinting factor of the MIP is 3.50 with relative standard deviation (5.63%). In summary, the use of DES as a functional monomer in molecular imprinting technology provides a novel, efficient, and biocompatible method for the isolation and purification of proteins. Graphical abstract ᅟ.

Biotin-Tagged Polysaccharide Vesicular Nanocarriers for Receptor-Mediated Anticancer Drug Delivery in Cancer Cells

Biotin-conjugated multistimuli-responsive polysaccharide vesicular nanocarriers are designed and developed, for the first time, to accomplish receptor-mediated endocytosis in cancer cells and to deliver anticancer drugs to intracellular compartments. For this purpose, a new renewable hydrophobic unit was custom designed with redox-degradable disulfide and enzyme-biodegradable aliphatic ester chemical linkages, and it was conjugated along with biotin on the dextran backbone. The dextran derivative self-assembled into nanovesicles of <200 nm in size, which were characterized by dynamic and static light scattering, electron, and atomic force microscopes. Avidin-HABA assay established the high affinity of biotin-tagged dextran vesicles toward membrane-receptors up to 25 nM concentration. Doxorubicin-hydrochloride (DOX.HCl)-loaded dextran vesicles exhibited stable formulation in phosphate-buffered saline (PBS) and fetal bovine serum (FBS). Redox-degradation by glutathione (GSH) showed 60% drug release, whereas lysosomal esterase enzyme enabled >98% drug release in 12 h. Confocal microscope and flow cytometry-assisted time-dependent cellular uptake studies revealed that the biotin-receptors overexpressed in cervical cancer cells (HeLa) exhibited larger drug accumulation through the receptor-assisted endocytosis process. This process enabled the delivery of higher amount of DOX and significantly enhanced the killing in cancer cells (HeLa) compared to wild-type mouse embryonic fibroblast cells (WT-MEF, normal cells). Control experiments such as biotin pretreatment in cancer cells and energy-suppressed cellular uptake at 4 °C further supported the occurrence of receptor-mediated endocytosis by the biotin-tagged polymer vesicles. This report provides first insights into the targeted polysaccharide vesicle platform, and the proof-of-concept is successfully demonstrated in biotin receptor-overexpressed cervical cancer cells.

Transferrin receptor 1 in cancer: a new sight for cancer therapy

Iron as an important element plays crucial roles in various physiological and pathological processes. Iron metabolism behaves in systemic and cellular two levels that usually are in balance conditions. The disorders of the iron metabolism balances relate with many kinds of diseases including Alzheimer's disease, osteoporosis and various cancers. In systemic iron metabolism that is regulated by hepcidin-ferroportin axis, plasma iron is bound with transferrin (TF) which has two high-affinity binding sites for ferric iron. The generic cellular iron metabolism consists of iron intake, utilization and efflux. During the iron intake process in generic cells, transferrin receptors (TFRs) act as the most important receptor mediated controls. TFR1 and TFR2 are two subtypes of TFRs those bind with iron-transferrin complex to facilitate iron into cells. TFR1 is ubiquitously expressed on the surfaces of generic cells, whereas TFR2 is specially expressed in liver cells. TFR1 has attracted more attention than TFR2 by having diverse functions in both invertebrates and vertebrates. Recently reports showed that TFR1 involved in many kinds of diseases including anemia, neurodegenerative diseases and cancers. Most importantly, TFR1 has been verified to be abnormally expressed in various cancers. Some experimental and clinical drugs and antibodies targeting TFR1 have showed strong anti-tumor effects, herein TFR1 probably become a potential molecular target for diagnosis and treatment for cancer therapy. This paper reviewed the research progresses of the roles of TFR1 in the tumorigenesis and cancer progression, the regulations of TFR1, and the therapeutic effects of targeting TFR1 on many kinds of cancers.

Targeting Liver Cancer and Associated Pathologies in Mice with a Mitochondrial VDAC1-Based Peptide

Hepatocellular carcinoma (HCC) is the third most lethal cancer worldwide. Despite progress in identifying risk factors, the incidence of HCC is increasing. Moreover, therapeutic options are limited and survival is poor. Therefore, alternative and innovative therapeutic strategies are urgently required. R-Tf-D-LP4, a cell-penetrating peptide derived from the mitochondrial multifunctional protein the voltage-dependent anion channel (VDAC1), is identified here as a highly effective liver cancer treatment. Recently, we demonstrated that R-Tf-D-LP4 induced apoptosis and inhibited tumor growth in mouse models. We now demonstrate that R-Tf-D-LP4 induced apoptosis in cancer liver-derived cell lines and inhibited tumor growth in three different liver cancer mouse models. These included diethylnitrosamine (DEN)-induced HCC, metabolically high-fat diet-induced HCC, and using a subcutaneous HepG2 cell xenograft model. Intravenous injection of the peptide into tumor-carrying DEN-treated mice resulted in dose-dependent inhibition of tumor growth up to complete tumor elimination. TUNEL staining of liver sections demonstrated peptide-induced apoptosis. Hematoxylin/eosin and Sirius red staining of liver sections showed decreased fibrotic formation. Immunohistochemical staining demonstrated reduced numbers of α-SMA-expressing cells in R-Tf-D-LP4-treated mouse livers. Additionally, macrophage presence in liver tissue was reduced in R-Tf-D-LP4-treated mice. Liver sections from DEN-treated mice showed steatohepatic pathology, reflected as fatty liver, inflammation, ballooning degeneration, and fibrosis; all were eliminated upon peptide treatment. Peptide treatment also inhibited tumor development in a nonalcoholic steatohepatitis-hepatocellular carcinoma mouse model induced by HFD. In HepG2 subcutaneous tumor xenografts, R-Tf-D-LP4 inhibited tumor growth.

CONCLUSION

These results show that the VDAC1-based peptide R-Tf-D-LP4 has multiple effects on liver cancer cells, leading to impairment of cell energy and metabolism homeostasis, induction of apoptosis, and elimination of liver cancer-associated processes, and thus represents a promising therapeutic approach for liver cancer.

Pro-apoptotic peptides-based cancer therapies: challenges and strategies to enhance therapeutic efficacy

Cancer is a leading cause of death worldwide. Despite many advances in the field of cancer therapy, an effective cure is yet to be found. As a more potent alternative for the conventional small molecule anti-cancer drugs, pro-apoptotic peptides have emerged as a new class of anticancer agents. By interaction with certain members in the apoptotic pathways, they could effectively kill tumor cells. However, there remain bottleneck challenges for clinical application of these pro-apoptotic peptides in cancer therapy. In this review, we will overview the developed pro-apoptotic peptides and outline the widely adopted molecular-based and nanoparticle-based strategies to enhance their anti-tumor effects.

Alterations in Cellular Iron Metabolism Provide More Therapeutic Opportunities for Cancer

Iron is an essential element for the growth and proliferation of cells. Cellular iron uptake, storage, utilization and export are tightly regulated to maintain iron homeostasis. However, cellular iron metabolism pathways are disturbed in most cancer cells. To maintain rapid growth and proliferation, cancer cells acquire large amounts of iron by altering expression of iron metabolism- related proteins. In this paper, normal cellular iron metabolism and the alterations of iron metabolic pathways in cancer cells were summarized. Therapeutic strategies based on targeting the altered iron metabolism were also discussed and disrupting redox homeostasis by intracellular high levels of iron provides new insight for cancer therapy. Altered iron metabolism constitutes a promising therapeutic target for cancer therapy.

Ferritin Nanocarrier Traverses the Blood Brain Barrier and Kills Glioma

Over the last decades, considerable efforts have been put into developing active nanocarrier systems that cross the blood brain barrier (BBB) to treat brain-related diseases such as glioma tumors. However, to date none have been approved for clinical usage. Here, we show that a human H-ferritin (HFn) nanocarrier both successfully crosses the BBB and kills glioma tumor cells. Its principle point of entry is the HFn receptor (transferrin receptor 1), which is overexpressed in both BBB endothelial cells (ECs) and glioma cells. Importantly, we found that HFn enters and exits the BBB via the endosome compartment. In contrast, upon specifically targeting and entering glioma cells, nearly all of the HFn accumulated in the lysosomal compartment, resulting in the killing of glioma tumor cells, with no HFn accumulation in the surrounding healthy brain tissue. Thus, HFn is an ideal nanocarrier for glioma therapy and possesses the potential to serve as a therapeutic approach against a broad range of central nervous system diseases.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

Selective induction of cancer cell death by VDAC1-based peptides and their potential use in cancer therapy

Mitochondrial VDAC1 mediates cross talk between the mitochondria and other parts of the cell by transporting anions, cations, ATP, Ca²⁺, and metabolites and serves as a key player in apoptosis. As such, VDAC1 is involved in two important hallmarks of cancer development, namely energy and metabolic reprograming and apoptotic cell death evasion. We previously developed cell‐penetrating VDAC1‐derived peptides that interact with hexokinase (HK), Bcl‐2, and Bcl‐xL to prevent the anti‐apoptotic activities of these proteins and induce cancer cell death, with a focus on leukemia and glioblastoma. In this study, we demonstrated the sensitivity of a panel of genetically characterized cancer cell lines, differing in origin and carried mutations, to VDAC1‐based peptide‐induced apoptosis. Noncancerous cell lines were less affected by the peptides. Furthermore, we constructed additional VDAC1‐based peptides with the aim of improving targeting, selectivity, and cellular stability, including R‐Tf‐D‐LP4, containing the transferrin receptor internalization sequence (Tf) that allows targeting of the peptide to cancer cells, known to overexpress the transferrin receptor. The mode of action of the VDAC1‐based peptides involves HK detachment, interfering with the action of anti‐apoptotic proteins, and thus activating multiple routes leading to an impairment of cell energy and metabolism homeostasis and the induction of apoptosis. Finally, in xenograft glioblastoma, lung, and breast cancer mouse models, R‐Tf‐D‐LP4 inhibited tumor growth while inducing massive cancer cell death, including of cancer stem cells. Thus, VDAC1‐based peptides offer an innovative new conceptual framework for cancer therapy.

Targeting and delivery of therapeutic enzymes

Biotechnology has revolutionized therapeutics for the treatment of a wide range of diseases. Recent advances in protein engineering and material science have made the targeted delivery of enzyme therapeutics using nanocarriers (NCs) a new model of treatment. Several NCs have been approved for clinical use in drug delivery. Despite their advantages, few NCs have been approved to deliver enzyme cargo in a targeted manner. This review details the current arsenal of platforms developed to deliver enzyme therapeutics as well as the advantages and challenges of using enzymes as drugs, with examples from the literature, and discusses the benefits and liabilities of a given approach. We conclude by providing a perspective on how this field may evolve over the near and long-term.

Contribution of three-dimensional architecture and tumor-associated fibroblasts to hepcidin regulation in breast cancer

Hepcidin is a peptide hormone that negatively regulates iron efflux and plays an important role in controlling the growth of breast tumors. In patients with breast cancer, the combined expression of hepcidin and its membrane target, ferroportin, predict disease outcome. However, mechanisms that control hepcidin expression in breast cancer cells remain largely unknown. Here we use three-dimensional breast cancer spheroids derived from cell lines and breast cancer patients to probe mechanisms of hepcidin regulation in breast cancer. We observe that the extent of hepcidin induction and pathways of its regulation are markedly changed in breast cancer cells grown in three dimensions. In monolayer culture, BMPs, particularly BMP6, regulate hepcidin transcription. When breast cancer cells are grown as spheroids, there is a >10 fold induction in hepcidin transcripts. Microarray analysis combined with knockdown experiments reveal that GDF-15 is the primary mediator of this change. The increase in hepcidin as breast cells develop a three-dimensional architecture increases intracellular iron, as indicated by an increase in the iron storage protein ferritin. Immunohistochemical staining of human breast tumors confirms that both GDF-15 and hepcidin are expressed in breast cancer specimens. Further, levels of GDF-15 are significantly correlated with levels of hepcidin at both the mRNA and protein level in patient samples, consistent with a role for GDF-15 in control of hepcidin in human breast tumors. Inclusion of tumor-associated fibroblasts in breast cancer spheroids further induces hepcidin. This induction is mediated by fibroblast-dependent secretion of IL-6. Breast cancer cells grown as spheroids are uniquely receptive to IL-6-dependent induction of hepcidin by tumor-associated fibroblasts, since IL-6 does not induce hepcidin in cells grown as monolayers. Collectively, our results suggest a new paradigm for tumor-mediated control of iron through the control of hepcidin by tumor architecture and the breast tumor microenvironment.

Efficacy and Mechanism of Antitumor Activity of an Antibody Targeting Transferrin Receptor 1 in Mouse Models of Human Multiple Myeloma

The transferrin receptor 1 (TfR1) is an attractive target for Ab-mediated cancer therapy. We previously developed a mouse/human chimeric IgG3 Ab (ch128.1) targeting human TfR1, which exhibits direct in vitro cytotoxicity against certain human malignant B cells through TfR1 degradation and iron deprivation. ch128.1 also demonstrates exceptional antitumor activity against the B cell malignancy multiple myeloma (MM) in xenograft models of SCID-Beige mice bearing either disseminated ARH-77 or KMS-11 cells in an early disease setting. Interestingly, this activity is observed even against KMS-11 cells, which show no sensitivity to the direct cytotoxic activity of ch128.1 in vitro. To understand the contributions of the Fc fragment, we generated a ch128.1 mutant with impaired binding to FcγRs and to the complement component C1q, which retains binding to the neonatal Fc receptor. We now report that this mutant Ab does not show antitumor activity in these two MM models, indicating a crucial role of the Fc fragment in the antitumor activity of ch128.1, which can be attributed to effector functions (Ab-dependent cell-mediated cytotoxicity, Ab-dependent cell-mediated phagocytosis, and/or complement-dependent cytotoxicity). Interestingly, in the KMS-11 model, complement depletion does not affect protection, whereas macrophage depletion does. Consistent with this observation, we found that ch128.1 induces Ab-dependent cell-mediated cytotoxicity and Ab-dependent cell-mediated phagocytosis against KMS-11 cells in the presence of murine bone marrow-derived macrophages. Finally, we found that ch128.1 therapy effectively increases survival in a late MM disease setting. Our results suggest that macrophages play a major role in ch128.1-mediated antitumor protection in our models and that ch128.1 can be effective against human B cell malignancies such as MM.

Total iron-binding capacity is a novel prognostic marker after curative gastrectomy for gastric cancer

BACKGROUND

Patients with gastric cancer (GC) are affected by changes in iron status. Before surgery, GC patients are likely to have iron-deficiency anemia; and after gastrectomy, patients suffer from low nutritional status and low iron. This study investigated preoperative iron status associated with prognosis after curative gastrectomy for gastric cancer.

METHODS

We evaluated preoperative serum hemoglobin (Hgb), Fe and total iron-binding capacity (TIBC) in 298 patients who underwent curative gastrectomy for GC without preoperative chemotherapy, and analyzed these factors' associations with prognosis after surgery.

RESULTS

Of the 298 patients, 129 (43.2%) had low Hgb levels, and 33 (11.1%) had low TIBC (< 260 µg/dl) that was not associated with Hgb or Fe level. Patients with low TIBC were significantly associated with older age (≥ 65 years old; P = 0.0085), low albumin (< 3.9 g/dl; P = 0.0388) and high CRP (≥ 0.15 mg/dl; P = 0.0018) in multivariate analysis. Low Fe (< 60 µg/dl) was not associated with disease-free survival (DFS) or overall survival (OS); however, low Fe was associated with longer cancer-specific survival in Stage III GC patients (P = 0.0333). Both low Hgb and low TIBC were significantly associated with shorter DFS (Hgb: P = 0.0433; TIBC: P < 0.0001) and shorter OS (Hgb: P = 0.0352; TIBC: P < 0.0001). Low TIBC were significantly associated with shorter DFS (HR 2.167, 95% CI 1.231-3.639, P = 0.0086) and shorter OS (HR 2.065, 95% CI 1.144-3.570, P = 0.0173) in multivariate Cox hazard regression analysis.

CONCLUSIONS

Preoperative serum TIBC level of GC patients who undergo curative gastrectomy is a novel prognostic marker in univariate and multivariate analyses.

Regulation of transferrin receptor-1 mRNA by the interplay between IRE-binding proteins and miR-7/miR-141 in the 3'-IRE stem-loops

Intracellular iron is tightly regulated by coordinated expression of iron transport and storage genes, such as transferrin receptor-1 (TfR1) and ferritin. They are primarily regulated by iron through iron-induced dissociation of iron-regulatory proteins (IRPs) from iron-responsive elements (IREs) in the 3'-UTR (untranslated region) of TfR1 or 5'-UTR of ferritin mRNA, resulting in destabilization of TfR1 mRNA and release of ferritin translation block. Thus high iron decreases iron transport via TfR1 mRNA degradation and increases iron storage via ferritin translational up-regulation. However, the molecular mechanism of TfR1 mRNA destabilization in response to iron remains elusive. Here, we demonstrate that miR-7-5p and miR-141-3p target 3'-TfR1 IREs and down-regulate TfR1 mRNA and protein expression. Conversely, miR-7-5p and miR-141-3p antagomiRs partially but significantly blocked iron- or IRP knockdown-induced down-regulation of TfR1 mRNA, suggesting the interplay between these microRNAs and IRPs along with involvement of another uncharacterized mechanism in TfR1 mRNA degradation. Luciferase reporter assays using 3'-UTR TfR1 IRE mutants suggested that the IREs C and E are targets of miR-7-5p and miR-141-3p, respectively. Furthermore, miR-7 expression was inversely correlated with TfR1 mRNA in human pancreatic adenocarcinoma patient samples. These results suggest a role of microRNAs in the TfR1 regulation in the IRP-IRE system.

Mitochondrial VDAC1-based peptides: Attacking oncogenic properties in glioblastoma

Glioblastoma multiforme (GBM), a primary brain malignancy characterized by high morbidity, invasiveness, proliferation, relapse and mortality, is resistant to chemo- and radiotherapies and lacks effective treatment. GBM tumors undergo metabolic reprograming and develop anti-apoptotic defenses. We targeted GBM with a peptide derived from the mitochondrial protein voltage-dependent anion channel 1 (VDAC1), a key component of cell energy, metabolism and apoptosis regulation. VDAC1-based cell-penetrating peptides perturbed cell energy and metabolic homeostasis and induced apoptosis in several GBM and GBM-derived stem cell lines. We found that the peptides simultaneously attacked several oncogenic properties of human U-87MG cells introduced into sub-cutaneous xenograft mouse model, inhibiting tumor growth, invasion, and cellular metabolism, stemness and inducing apoptosis. Peptide-treated tumors showed decreased expression of all tested metabolism-related enzymes and transporters, and elevated levels of apoptotic proteins, such as p53, cytochrome c and caspases. Retro-Tf-D-LP4, containing the human transferrin receptor (TfR)-recognition sequence, crossed the blood-brain barrier (BBB) via the TfR that is highly expressed in the BBB to strongly inhibit tumor growth in an intracranial xenograft mouse model. In summary, the VDAC1-based peptides tested here offer a potentially affordable and innovative new conceptual therapeutic paradigm that might overcome GBM stemness and invasiveness and reduce relapse rates.

Calcium phosphate-based nanosystems for advanced targeted nanomedicine

Synthetic calcium phosphates (CaPs) are the most widely accepted bioceramics for the repair and reconstruction of bone tissue defects. The recent advancements in materials science have prompted a rapid progress in the preparation of CaPs with nanometric dimensions, tailored surface characteristics, and colloidal stability opening new perspectives in their use for applications not strictly related to bone. In particular, the employment of CaPs nanoparticles as carriers of therapeutic and imaging agents has recently raised great interest in nanomedicine. CaPs nanoparticles, as well as other kinds of nanoparticles, can be engineered to specifically target the site of the disease (cells or organs), thus minimizing their dispersion in the body and undesired organism-nanoparticles interactions. The most promising and efficient approach to improve their specificity is the 'active targeting', where nanoparticles are conjugated with a targeting moiety able to recognize and bind with high efficacy and selectivity to receptors that are highly expressed only in the therapeutic site. The aim of this review is to give an overview on advanced targeted nanomedicine with a focus on the most recent reports on CaP nanoparticles-based systems, specifically designed for the active targeting. The distinctive characteristics of CaP nanoparticles with respect to the other kinds of nanomaterials used in nanomedicine are also discussed.

Ligand Size and Conformation Affect the Behavior of Nanoparticles Coated with in Vitro and in Vivo Protein Corona

Protein corona is immediately established on the surface of nanoparticles upon their introduction into biological milieu. Several studies have shown that the targeting efficiency of ligand-modified nanoparticles is attenuated or abolished owing to the protein adsorption. Here, transferrin receptor-targeting ligands, including LT7 (CHAIYPRH), DT7 (hrpyiahc, all d-form amino acids), and transferrin, were used to identify the influence of the ligand size and conformation on protein corona formation. The results showed that the targeting capacity of ligand-modified nanoparticles was lost after incubation with plasma in vitro, whereas it was partially retained after in vivo corona formation. Results from sodium dodecyl sulfate polyacrylamide gel electrophoresis and liquid chromatography-mass spectrometry revealed the difference in the composition of in vitro and in vivo corona, wherein the ligand size and conformation played a critical role. Differences were observed in cellular internalization and exocytosis profiles on the basis of the ligand and corona source.

Organ-based drug delivery

The phenomenal advances in pharmaceutical sciences over the last few decades have led to the development of new therapeutics like peptides, proteins, RNAs, DNAs and highly potent small molecules. Fruitful applications of these therapeutics have been challenged by several anatomical and physiological barriers that limit adequate drug disposition at the site-of-action and by off-target drug distribution to undesired tissues, which together result in the reduced effectiveness and increased side effects of therapeutic agents. As such, the development of drug delivery and targeting systems has been recognised as a cornerstone for future drug development. Research in pharmaceutical sciences is now devoted to tackling delivery challenges through engineering delivery systems that move beyond conventional dosage forms and regimens into state-of-the-art targeted drug delivery tailored toward specific therapeutic needs. Modern drug delivery systems comprise passive and active targeting approaches. While passive targeting relies on the natural course of distribution of drugs or drug carriers in the body, as governed by their physicochemical properties, active targeting often exploits targeting moieties that home preferentially into target tissues. Here, we provide an overview of theories of and approaches to passive and active drug delivery. As the design of drug delivery is dependent on the unique structure of target tissues and organs, we present our discussion in an organ-specific manner with the aim to inspire the development of new strategies for curing disease with high accuracy and efficiency.

Differential regulation of hepcidin in cancer and non-cancer tissues and its clinical implications

Hepcidin is a crucial peptide for regulating cellular iron efflux. Because iron is essential for cell survival, especially for highly active cells, such as tumor cells, it is imperative to understand how tumor cells manipulate hepcidin expression for their own metabolic needs. Studies suggest that hepcidin expression and regulation in tumor cells show important differences in comparison with those in non-tumorous cells. These differences should be investigated to develop new strategies to fight cancer cells. Manipulating hepcidin expression to starve cancer cells for iron may prove to be a new therapy in the anticancer arsenal.

Human platelets repurposed as vehicles for in vivo imaging of myeloma xenotransplants

Human platelets were identified in tumors by Trousseau in 1865, although their roles in tumor microenvironments have only recently attracted the attention of cancer researchers. In this study we exploit and enhance platelet interactions in tumor microenvironments by introducing tumor-targeting and imaging functions. The first step in repurposing human platelets as vehicles for tumor-targeting was to inhibit platelet-aggregation by cytoplasmic-loading of kabiramide (KabC), a potent inhibitor of actin polymerization and membrane protrusion. KabC-Platelets can accumulate high levels of other membrane-permeable cytoxins and probes, including epidoxorubicin, carboxyfluorescein di-ester and chlorin-e6. Finally, mild reaction conditions were developed to couple tumor-targeting proteins and antibodies to KabC-platelets. Fluorescence microscopy studies showed KabC-platelets, surface-coupled with transferrin and Cy5, bind specifically to RPMI8226 and K562 cells, both of which over-express the transferrin receptor. Repurposed platelets circulate for upto 9-days a feature that increases their chance of interacting with target cells. KabC-platelets, surface-coupled with transferrin and Cy7, or chlorin-e6, and injected in immuno-compromised mice were shown to accumulate specifically in sub-cutaneous and intra-cranial myeloma xenotransplants. The high-contrast, in vivo fluorescence images recorded from repurposed platelets within early-stage myeloma is a consequence in part of their large size (φ∼2μm), which allows them to transport 100 to 1000-times more targeting-protein and probe molecules respectively. Human platelets can be configured with a plurality of therapeutic and targeting antibodies to help stage tumor environments for an immunotherapy, or with combinations of therapeutic antibodies and therapeutic agents to target and treat cardiovascular and neurologic diseases.

Novel PAMAM-PEG-Peptide Conjugates for siRNA Delivery Targeted to the Transferrin and Epidermal Growth Factor Receptors

The transferrin (TfR) and epidermal growth factor receptors (EGFR) are known to be overexpressed on the surface of a wide variety of tumor cells. Therefore, the peptides B6 (TfR specific) and GE11 (targeted to the EGFR) were linked to the PAMAM (polyamidoamine) structure via a polyethylenglycol (PEG) 2 kDa chain with the aim of improving the silencing capacity of the PAMAM-based dendriplexes. The complexes showed an excellent binding capacity to the siRNA with a maximal condensation at nitrogen/phosphate (N/P) 2. The nanoparticles formed exhibited hydrodynamic diameters below 200 nm. The zeta potential was always positive, despite the complexes containing the PEG chain in the structure showing a drop of the values due to the shielding effect. The gene silencing capacity was assayed in HeLa and LS174T cells stably transfected with the eGFPLuc cassette. The dendriplexes containing a specific anti luciferase siRNA, assayed at different N/P ratios, were able to mediate a mean decrease of the luciferase expression values of 14% for HeLa and 20% in LS174T cells, compared to an unspecific siRNA-control. (p < 0.05). In all the conditions assayed, dendriplexes resulted to be non-toxic and viability was always above 75%.

Noninvasive 89Zr-Transferrin PET Shows Improved Tumor Targeting Compared with 18F-FDG PET in MYC-Overexpressing Human Triple-Negative Breast Cancer

The current standard for breast PET imaging is 18F-FDG. The heterogeneity of 18F-FDG uptake in breast cancer limits its utility, varying greatly among receptor status, histopathologic subtypes, and proliferation markers. 18F-FDG PET often exhibits nonspecific internalization and low specificity and sensitivity, especially with tumors smaller than 1 cm3 MYC is a protein involved in oncogenesis and is overexpressed in triple-negative breast cancer (TNBC). Increased surface expression of transferrin receptor (TfR) is a downstream event of MYC upregulation and has been validated as a clinically relevant target for molecular imaging. Transferrin labeled with 89Zr has successfully identified MYC status in many cancer subtypes preclinically and been shown to predict response and changes in oncogene status via treatment with small-molecule inhibitors that target MYC and PI3K signaling pathways. We hypothesized that 89Zr-transferrin PET will noninvasively detect MYC and TfR and improve upon the current standard of 18F-FDG PET for MYC-overexpressing TNBC. Methods: In this study, 89Zr-transferrin and 18F-FDG imaging were compared in preclinical models of TNBC. TNBC cells (MDA-MB-157, MDA-MB-231, and Hs578T) were treated with bromodomain-containing protein 4 (BRD4) inhibitors JQ1 and OTX015 (0.5-1 μM). Cell proliferation, gene expression, and protein expression were assayed to explore the effects of these inhibitors on MYC and TfR. Results: Head-to-head comparison showed that 89Zr-transferrin targets TNBC tumors significantly better (P < 0.05-0.001) than 18F-FDG through PET imaging and biodistribution studies in MDA-MB-231 and MDA-MB-157 xenografts and a patient-derived xenograft model of TNBC. c-Myc and TfR gene expression was decreased upon treatment with BRD4 inhibitors and c-MYC small interfering RNA (P < 0.01-0.001 for responding cell lines), compared with vehicle treatment. MYC and TfR protein expression, along with receptor-mediated internalization of transferrin, was also significantly decreased upon drug treatment in MDA-MB-231 and MDA-MB-157 cells (P < 0.01-0.001). Conclusion:89Zr-transferrin targets human TNBC primary tumors significantly better than 18F-FDG, as shown through PET imaging and biodistribution studies. 89Zr-transferrin is a useful tool to interrogate MYC via TfR-targeted PET imaging in TNBC.

Particle Targeting in Complex Biological Media

Over the past few decades, nanoengineered particles have gained increasing interest for applications in the biomedical realm, including diagnosis, imaging, and therapy. When functionalized with targeting ligands, these particles have the potential to interact with specific cells and tissues, and accumulate at desired target sites, reducing side effects and improve overall efficacy in applications such as vaccination and drug delivery. However, when targeted particles enter a complex biological environment, the adsorption of biomolecules and the formation of a surface coating (e.g., a protein corona) changes the properties of the carriers and can render their behavior unpredictable. For this reason, it is of importance to consider the potential challenges imposed by the biological environment at the early stages of particle design. This review describes parameters that affect the targeting ability of particulate drug carriers, with an emphasis on the effect of the protein corona. We highlight strategies for exploiting the protein corona to improve the targeting ability of particles. Finally, we provide suggestions for complementing current in vitro assays used for the evaluation of targeting and carrier efficacy with new and emerging techniques (e.g., 3D models and flow-based technologies) to advance fundamental understanding in bio-nano science and to accelerate the development of targeted particles for biomedical applications.

Recent Advances in Nanoparticle-Based Cancer Drug and Gene Delivery

Effective and safe delivery of anticancer agents is among the major challenges in cancer therapy. The majority of anticancer agents are toxic to normal cells, have poor bioavailability, and lack in vivo stability. Recent advancements in nanotechnology provide safe and efficient drug delivery systems for successful delivery of anticancer agents via nanoparticles. The physicochemical and functional properties of the nanoparticle vary for each of these anticancer agents, including chemotherapeutics, nucleic acid-based therapeutics, small molecule inhibitors, and photodynamic agents. The characteristics of the anticancer agents influence the design and development of nanoparticle carriers. This review focuses on strategies of nanoparticle-based drug delivery for various anticancer agents. Recent advancements in the field are also highlighted, with suitable examples from our own research efforts and from the literature.

Effect of the FE2+ chelation by 2,2'-dipyridyl in the doxorubicin-induced lethality in breast tumor cell lines

Breast cancer cells may exhibit changes in iron homeostasis, which results in increased labile iron pool (LIP) levels. Several studies highlight the crucial role of high LIP levels in the maintenance of tumor cell physiology. Iron chelators have been tested in anticancer therapy in combination with chemotherapeutic agents, to improve drug efficacy. Thus, the aim of this study was to evaluate the effect of 2,2'-dipyridyl (DIP), a Fe²⁺ chelator, in combination with doxorubicin (DOX) in breast tumor cells. The maximum concentration of DIP that did not significantly reduce the viability of MDA-MB-231 cells was 10μM and for MCF-7 cells was 50μM. We observed that MCF-7 had higher LIP levels than MDA-MB-231 cells. DIP alone increased ROS generation in MCF-7 cells, and DIP pretreatment reduced ROS generation induced by DOX treatment. In conclusion, the increase in MCF-7 cell viability induced by DIP pretreatment in DOX-treated cells seems to be related to an increase in the cellular antioxidant capacity and the iron chelator did not improve drug efficacy in the two breast tumor cell lines analyzed.

Zebrafish: A Visual Model To Evaluate the Biofate of Transferrin Receptor-Targeted 7Peptide-Decorated Coumarin 6 Micelles

In the present study, the zebrafish was explored as an in vivo model to assess the biofate of transferrin receptor (TfR)-targeted coumarin 6 (C6) micelles across various biological barriers. Three 7peptide (7pep)-decorated poly(ethylene glycol)-block-poly(ε-caprolactone) micelles loaded with fluorescence coumarin 6 (7pep-M-C6) with different ligand densities were constructed with particle sizes between 30 and 40 nm. Whole-mount immunostaining revealed that the expression level of TfR in the retina, brain, and intestine increased along with development stage. Compared to unmodified micelles, 7pep-M-C6 demonstrated higher uptake efficiency in the larval zebrafish. Preinhibition of TfR with 7pep implicated the TfR-mediated endocytosis pathway in the uptake of 7pep-M-C6. Confocal images of the larval zebrafish eye and brain showed the efficient delivery of C6 across the retinal pigment epithelial to the ganglion cell layer and the significant accumulation of C6 in all brain tissues, respectively, which plateaued when the ligand density was 10%. To investigate the intestinal distribution of C6, micelles were administered to adult zebrafish via gavaging. Notably, 7pep-M-C6 enhanced the transport of C6 across the villi and increased its aggregation into the basolateral membrane of the intestine. After the oral administration of 7pep-M-C6, C6 accumulated in the eye and brain. Förster resonance energy transfer analysis suggested that intact 7pep-modified micelles could enter the epithelial cells of the intestine, brain, and eye after oral administration in adult zebrafish. In conclusion, zebrafish could be used as a model for in vivo visual assessment of the biofate of TfR-targeted drug delivery systems.

A quantitative comparison of cytosolic delivery via different protein uptake systems

Over many years, a variety of delivery systems have been investigated that have the capacity to shuttle macromolecular cargoes, especially proteins, into the cytosol. Due to the lack of an objective way to quantify cytosolic delivery, relative delivery efficiencies of the various transport systems have remained unclear. Here, we demonstrate the use of the biotin ligase assay for a quantitative comparison of protein transport to the cytosol via cell-penetrating peptides, supercharged proteins and bacterial toxins in four different cell lines. The data illustrate large differences in both the total cellular internalization, which denotes any intracellular location including endosomes, and in the cytosolic uptake of the transport systems, with little correlation between the two. Also, we found significant differences between the cell lines. In general, protein transport systems based on cell-penetrating peptides show a modest total uptake, and mostly do not deliver cargo to the cytosol. Systems based on bacterial toxins show a modest receptor-mediated internalization but an efficient delivery to the cytosol. Supercharged proteins, on the contrary, are not receptor-specific and lead to massive total internalization into endosomes, but only low amounts end up in the cytosol.

Nanoparticle as a novel tool in hyperthermic intraperitoneal and pressurized intraperitoneal aerosol chemotheprapy to treat patients with peritoneal carcinomatosis

The treatment of peritoneal surface malignances has changed considerably over the last thirty years. Unfortunately, the palliative is the only current treatment for peritoneal carcinomatosis (PC). Two primary intraperitoneal chemotherapeutic methods are used. The first is combination of cytoreductive surgery (CRS) and Hyperthermic IntraPEritoneal Chemotherapy (HIPEC), which has become the gold standard for many cases of PC. The second is Pressurized IntraPeritoneal Aerosol Chemotheprapy (PIPAC), which is promising direction to minimally invasive as safedrug delivery. These methods were improved through multicenter studies and clinical trials that yield important insights and solutions. Major method development has been made through nanomedicine, specifically nanoparticles. Here, we are presenting the latest advances of nanoparticles and their application to precision diagnostics and improved treatment strategies for PC. These advances will likely develop both HIPEC and PIPAC methods that used for in vitro and in vivo studies. Several benefits of using nanoparticles will be discussed including: 1) Nanoparticles as drug delivery systems; 2) Nanoparticles and Near Infrred (NIR) Irradiation; 3) use of nanoparticles in perioperative diagnostic and individualized treatment planning; 4) use of nanoparticles as anticancer dressing's, hydrogels and as active beeds for optimal reccurence prevention; and 5) finally the curent in vitro and in vivo studies and clinical trials of nanoparticles. The current review highlighted use of nanoparticles as novel tools in improving drug delivery to be effective for treatment patients with peritoneal carcinomatosis.

H-Ferritin Enriches the Curcumin Uptake and Improves the Therapeutic Efficacy in Triple Negative Breast Cancer Cells

Triple negative breast cancer (TNBC) is a highly aggressive, invasive, and metastatic tumor. Although it is reported to be sensitive to cytotoxic chemotherapeutics, frequent relapse and chemoresistance often result in treatment failure. In this study, we developed a biomimetic nanodrug consisting of a self-assembling variant (HFn) of human apoferritin loaded with curcumin. HFn nanocage improved the solubility, chemical stability, and bioavailability of curcumin, allowing us to reliably carry out several experiments in the attempt to establish the potential of this molecule as a therapeutic agent and elucidate the mechanism of action in TNBC. HFn biopolymer was designed to bind selectively to the TfR1 receptor overexpressed in TNBC cells. HFn-curcumin (CFn) proved to be more effective in viability assays compared to the drug alone using MDA-MB-468 and MDA-MB-231 cell lines, representative of basal and claudin-low TNBC subtypes, respectively. Cellular uptake of CFn was demonstrated by flow cytometry and label-free confocal Raman imaging. CFn could act as a chemosensitizer enhancing the cytotoxic effect of doxorubicin by interfering with the activity of multidrug resistance transporters. In addition, CFn exhibited different cell cycle effects on these two TNBC cell lines, blocking MDA-MB-231 in G0/G1 phase, whereas MDA-MB-468 accumulated in G2/M phase. CFn was able to inhibit the Akt phosphorylation, suggesting that the effect on the proliferation and cell cycle involved the alteration of PI3K/Akt pathway.

Peptide ligand-modified nanomedicines for targeting cells at the tumor microenvironment

Since their initial discovery more than 30years ago, tumor-homing peptides have become an increasingly useful tool for targeted delivery of therapeutic and diagnostic agents into tumors. Today, it is well accepted that cells at the tumor microenvironment (TME) contribute in many ways to cancer development and progression. Tumor-homing peptide-decorated nanomedicines can interact specifically with surface receptors expressed on cells in the TME, improve cellular uptake of nanomedicines by target cells, and impair tumor growth and progression. Moreover, peptide ligand-modified nanomedicines can potentially accumulate in the target tissue at higher concentrations than would small conjugates, thus increasing overall target tissue exposure to the therapeutic agent, enhance therapeutic efficacy and reduce side effects. This review describes the most studied peptide ligands aimed at targeting cells in the TME, discusses major obstacles and principles in the design of ligands for drug targeting and provides an overview of homing peptides in ligand-targeted nanomedicines that are currently in development for cancer therapy and diagnosis.

Fattigation-platform nanoparticles using apo-transferrin stearic acid as a core for receptor-oriented cancer targeting

A major hurdle in cancer treatment is the precise targeting of drugs to the cancer site. As many cancer cells overexpress the transferrin receptor (TfR), the transferrin (Tf)-TfR interaction is widely exploited to target cancer cells. In this study, novel amphiphilic apo-Tf stearic acid (TfS) conjugates were prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry, and trinitrobenzenesulfonic acid (TNBS) assay. The prepared TfS conjugates were readily self-assembled in water to form nanoparticles (NPs), consisting of TfS as a core of NPs, whose sizes and zeta potentials were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a particle size analyzer. Hydrophilic water-soluble doxorubicin (DOX) was chosen as a model drug. DOX-loaded TfS NPs (NP+DOX), prepared by the adsorption of DOX on the NP surface via the incubation method, were analyzed for their cell targeting and killing efficiencies in TfR-overexpressing A549 and HCT116 cell lines by MTT assay, confocal microscopy, and fluorescence assisted cell sorting (flow cytometry). The data showed that NP+DOX exhibited improved cancer cell targeting and killing properties compared to that reported for free DOX. Further, the cytotoxic efficiency of NP+DOX was comparable to that of PEGylated liposomal product, Doxil^®, while its cellular uptake was higher than that of Doxil^®. Thus, this novel receptor-based TfS NP drug delivery system has great potential to target TfR-overexpressing cancer cells without off-target effects.

Fluorescence imaging of bombesin and transferrin receptor expression is comparable to 18F-FDG PET in early detection of sorafenib-induced changes in tumor metabolism

Physical measurement of tumor volume reduction is the most commonly used approach to assess tumor progression and treatment efficacy in mouse tumor models. However, it is relatively insensitive, and often requires long treatment courses to achieve gross physical tumor destruction. As alternatives, several non-invasive imaging methods such as bioluminescence imaging (BLI), fluorescence imaging (FLI) and positron emission tomography (PET) have been developed for more accurate measurement. As tumors have elevated glucose metabolism, 18F-fludeoxyglucose (18F-FDG) has become a sensitive PET imaging tracer for cancer detection, diagnosis, and efficacy assessment by measuring alterations in glucose metabolism. In particular, the ability of 18F-FDG imaging to detect drug-induced effects on tumor metabolism at a very early phase has dramatically improved the speed of decision-making regarding treatment efficacy. Here we demonstrated an approach with FLI that offers not only comparable performance to PET imaging, but also provides additional benefits, including ease of use, imaging throughput, probe stability, and the potential for multiplex imaging. In this report, we used sorafenib, a tyrosine kinase inhibitor clinically approved for cancer therapy, for treatment of a mouse tumor xenograft model. The drug is known to block several key signaling pathways involved in tumor metabolism. We first identified an appropriate sorafenib dose, 40 mg/kg (daily on days 0-4 and 7-10), that retained ultimate therapeutic efficacy yet provided a 2-3 day window post-treatment for imaging early, subtle metabolic changes prior to gross tumor regression. We then used 18F-FDG PET as the gold standard for assessing the effects of sorafenib treatment on tumor metabolism and compared this to results obtained by measurement of tumor size, tumor BLI, and tumor FLI changes. PET imaging showed ~55-60% inhibition of tumor uptake of 18F-FDG as early as days 2 and 3 post-treatment, without noticeable changes in tumor size. For comparison, two FLI probes, BombesinRSense™ 680 (BRS-680) and Transferrin-Vivo™ 750 (TfV-750), were assessed for their potential in metabolic imaging. Metabolically active cancer cells are known to have elevated bombesin and transferrin receptor levels on the surface. In excellent agreement with PET imaging, the BRS-680 imaging showed 40% and 79% inhibition on days 2 and 3, respectively, and the TfV-750 imaging showed 65% inhibition on day 3. In both cases, no significant reduction in tumor volume or BLI signal was observed during the first 3 days of treatment. These results suggest that metabolic FLI has potential preclinical application as an additional method for detecting drug-induced metabolic changes in tumors.

H-Ferritin-nanocaged olaparib: a promising choice for both BRCA-mutated and sporadic triple negative breast cancer

Poly(ADP-ribose) polymerase (PARP) inhibitors represent a promising strategy toward the treatment of triple-negative breast cancer (TNBC), which is often associated to genomic instability and/or BRCA mutations. However, clinical outcome is controversial and no benefits have been demonstrated in wild type BRCA cancers, possibly due to poor drug bioavailability and low nuclear delivery. In the attempt to overcome these limitations, we have developed H-Ferritin nanoformulated olaparib (HOla) and assessed its anticancer efficacy on both BRCA-mutated and non-mutated TNBC cells. We exploited the natural tumor targeting of H-Ferritin, which is mediated by the transferrin receptor-1 (TfR1), and its physiological tropism toward cell nucleus. TNBC cell lines over-expressing TfR-1 were successfully recognized by H-Ferritin, displaying a fast internalization into the cells. HOla induced remarkable cytotoxic effect in cancer cells, exhibiting 1000-fold higher anticancer activity compared to free olaparib (Ola). Accordingly, HOla treatment enhanced PARP-1 cleavage, DNA double strand breaks and Ola delivery into the nuclear compartment. Our findings suggest that H-Ferritin nanoformulation strongly enhances cytotoxic efficacy of Ola as a stand-alone therapy in both BRCA-mutated and wild type TNBC cells, by promoting targeted nuclear delivery.

Glycobiology of Eosinophilic Inflammation: Contributions of Siglecs, Glycans, and Other Glycan-Binding Proteins

The historical focus on protein-protein interactions in biological systems, at the expense of attention given to interactions between other classes of molecules, has overlooked important and clinically relevant processes and points of potential clinical intervention. For example, the significance of protein-carbohydrate interactions, especially in the regulation of immune responses, has recently received greater recognition and appreciation. This review discusses several ways by which cell-surface lectin-glycan interactions can modulate eosinophil function, particularly at the levels of eosinophil recruitment and survival, and how such interactions can be exploited therapeutically. A primary focus is on discoveries concerning Siglec-8, a glycan-binding protein selectively expressed on human eosinophils, and its closest functional paralog in the mouse, Siglec-F. Recent advances in the synthesis of polymeric ligands, the identification of physiological ligands for Siglec-8 and Siglec-F in the airway, and the determination of the basis of glycan ligand discrimination of Siglec-8 are discussed. Important similarities and differences between these siglecs are outlined. Eosinophil expression of additional glycan-binding proteins or their glycan ligands, including interactions involving members of the selectin, galectin, and siglec families, is summarized. The roles of these molecules in eosinophil recruitment, survival, and inflammation are described. Finally, the modulation of these interactions and potential therapeutic exploitation of glycan-binding proteins and their ligands to ameliorate eosinophil-associated diseases are considered.

Nanoparticles and targeted drug delivery in cancer therapy

Surgery, chemotherapy, radiotherapy, and hormone therapy are the main common anti-tumor therapeutic approaches. However, the non-specific targeting of cancer cells has made these approaches non-effective in the significant number of patients. Non-specific targeting of malignant cells also makes indispensable the application of the higher doses of drugs to reach the tumor region. Therefore, there are two main barriers in the way to reach the tumor area with maximum efficacy. The first, inhibition of drug delivery to healthy non-cancer cells and the second, the direct conduction of drugs into tumor site. Nanoparticles (NPs) are the new identified tools by which we can deliver drugs into tumor cells with minimum drug leakage into normal cells. Conjugation of NPs with ligands of cancer specific tumor biomarkers is a potent therapeutic approach to treat cancer diseases with the high efficacy. It has been shown that conjugation of nanocarriers with molecules such as antibodies and their variable fragments, peptides, nucleic aptamers, vitamins, and carbohydrates can lead to effective targeted drug delivery to cancer cells and thereby cancer attenuation. In this review, we will discuss on the efficacy of the different targeting approaches used for targeted drug delivery to malignant cells by NPs.

Iron-responsive element-binding protein 2 plays an essential role in regulating prostate cancer cell growth

Iron-responsive element-binding proteins (IRPs) are master regulators of cellular iron homeostasis. Our previous work demonstrated that iron homeostasis is altered in prostate cancer and contributes to prostate cancer progression. Here we report that prostate cancer cells overexpress IRP2 and that overexpression of IRP2 drives the altered iron phenotype of prostate cancer cells. IRP2 knockdown in prostate cancer cell lines reduces intracellular iron and causes cell cycle inhibition and apoptosis. Cell cycle analysis demonstrates that IRP2-depleted prostate cancer cells accumulate in G0/G1 due to induction of p15, p21, and p27. Activation of these pathways is sufficient to significantly reduce the growth of PC3 prostate tumors in vivo. In contrast, IRP1 knockdown does not affect iron homeostasis and only modestly affects cell growth, likely through an iron-independent mechanism. These results demonstrate that upregulation of IRP2 in prostate cancer cells co-opts normal iron regulatory mechanisms to facilitate iron retention and drive enhanced tumor growth.

Strategies for improving drug delivery: nanocarriers and microenvironmental priming

INTRODUCTION

The ultimate goal in the field of drug delivery is to exclusively direct therapeutic agents to pathological tissues in order to increase therapeutic efficacy and eliminate side effects. This goal is challenging due to multiple transport obstacles in the body. Strategies that improve drug transport exploit differences in the characteristics of normal and pathological tissues. Within the field of oncology, these concepts have laid the groundwork for a new discipline termed transport oncophysics. Areas covered: Efforts to improve drug biodistribution have mainly focused on nanocarriers that enable preferential accumulation of drugs in diseased tissues. A less common approach to enhance drug transport involves priming strategies that modulate the biological environment in ways that favor localized drug delivery. This review discusses a variety of priming and nanoparticle design strategies that have been used for drug delivery. Expert opinion: Combinations of priming agents and nanocarriers are likely to yield optimal drug distribution profiles. Although priming strategies have yet to be widely implemented, they represent promising solutions for overcoming biological transport barriers. In fact, such strategies are not restricted to priming the tumor microenvironment but can also be directed toward healthy tissue in order to reduce nanoparticle uptake.

Lipocalin 2: An Emerging Player in Iron Homeostasis and Inflammation

Lipocalin 2 (Lcn2), an innate immune protein, has emerged as a critical iron regulatory protein during physiological and inflammatory conditions. As a bacteriostatic factor, Lcn2 obstructs the siderophore iron-acquiring strategy of bacteria and thus inhibits bacterial growth. As part of host nutritional immunity, Lcn2 facilitates systemic, cellular, and mucosal hypoferremia during inflammation, in addition to stabilizing the siderophore-bound labile iron pool. In this review, we summarize recent advances in understanding the interaction between Lcn2 and iron, and its effects in various inflammatory diseases. Lcn2 exerts mostly a protective role in infectious and inflammatory bowel diseases, whereas both beneficial and detrimental functions have been documented in neurodegenerative diseases, metabolic syndrome, renal disorders, skin disorders, and cancer. Further animal and clinical studies are necessary to unveil the multifaceted roles of Lcn2 in iron dysregulation during inflammation and to explore its therapeutic potential for treating inflammatory diseases.

Multifunctional Polymer Nanoparticles for Dual Drug Release and Cancer Cell Targeting

Multifunctional polymer nanoparticles have been developed for cancer treatment because they could be easily designed to target cancer cells and to enhance therapeutic efficacy according to cancer hallmarks. In this study, we synthesized a pH-sensitive polymer, poly(methacrylic acid-co-histidine/doxorubicin/biotin) (HBD) in which doxorubicin (DOX) was conjugated by a hydrazone bond to encapsulate an immunotherapy drug, imiquimod (IMQ), to form dual cancer-targeting and dual drug-loaded nanoparticles. At low pH, polymeric nanoparticles could disrupt and simultaneously release DOX and IMQ. Our experimental results show that the nanoparticles exhibited pH-dependent drug release behavior and had an ability to target cancer cells via biotin and protonated histidine.

Tumor-targeted Nanoparticle Delivery of HuR siRNA Inhibits Lung Tumor Growth In Vitro and In Vivo By Disrupting the Oncogenic Activity of the RNA-binding Protein HuR

Selective downregulation of the human antigen R (HuR) protein by siRNA may provide a powerful approach for treating lung cancer. To this end, we investigated the efficacy of transferrin receptor-targeted liposomal nanoparticle-based HuR siRNA (HuR-TfNP) therapy and compared with control siRNA (C)-TfNP therapy both, in vitro and in vivo using lung cancer models. In vitro studies showed HuR-TfNP, but not C-TfNP, efficiently downregulated HuR and HuR-regulated proteins in A549, and HCC827 lung cancer cells, resulting in reduced cell viability, inhibition of cell migration and invasion, and induction of G₁ cell-cycle arrest culminating in apoptosis. However, HuR-TfNP activity in normal MRC-9 lung fibroblasts was negligible. In vivo biodistribution study demonstrated that fluorescently labeled HuR-siRNA or ICG dye-loaded TfNP localized in tumor tissues. Efficacy studies showed intratumoral or intravenous administration of HuR-TfNP significantly inhibited A549 (>55% inhibition) and HCC827 (>45% inhibition) subcutaneous tumor growth compared with C-TfNP. Furthermore, HuR-TfNP treatment reduced HuR, Ki67, and CD31 expression and increased caspase-9 and PARP cleavage and TUNEL-positive staining indicative of apoptotic cell death in tumor tissues compared with C-TfNP treatment. The antitumor activity of HuR-TfNP was also observed in an A549-luc lung metastatic model, as significantly fewer tumor nodules (9.5 ± 3.1; P < 0.001; 88% inhibition) were observed in HuR-TfNP-treated group compared with the C-TfNP-treated group (77.7 ± 20.1). Significant reduction in HuR, Ki67, and CD31 expression was also observed in the tumor tissues of HuR-TfNP-treatment compared with C-TfNP treatment. Our findings highlight HuR-TfNP as a promising nanotherapeutic system for lung cancer treatment. Mol Cancer Ther; 16(8); 1470-86. ©2017 AACR.