Suppression of axillary lymph node metastasis (ALNM) is an important goal in the treatment of breast cancer. While several therapies directed to ALNM have been evaluated, effective and safe ...treatments for ALNM in triple negative breast cancer (TNBC) have not been established yet, especially against initial/small metastases. Here, we demonstrated the therapeutic effect of an anthracycline drug, epirubicin (EPI)-loaded polymeric micelles equipped with pH-triggered drug release property (EPI/m) against ALNM of TNBC. EPI/m effectively inhibited the spread of the primary tumor and the growth of ALNM, through selective accumulation and penetration in both primary tumor and vascularized ALNM, as well as efficient drug activation triggered by the intratumoral acidic environment. Furthermore, we revealed that the improvement of the activated drug distribution of EPI/m contributed to dose-dependent enhancement of the antitumor effect through expansion of the therapeutic window. These findings highlight the utility of pH-responsive property in EPI/m for the treatment of ALNM in TNBC.
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Ligand-mediated drug delivery systems have enormous potential for improving the efficacy of cancer treatment. In particular, Arg-Gly-Asp peptides are promising ligand molecules for targeting ...αvβ3/αvβ5 integrins, which are overexpressed in angiogenic sites and tumors, such as intractable human glioblastoma (U87MG). We here achieved highly efficient drug delivery to U87MG tumors by using a platinum anticancer drug-incorporating polymeric micelle (PM) with cyclic Arg-Gly-Asp (cRGD) ligand molecules. Intravital confocal laser scanning microscopy revealed that the cRGD-linked polymeric micelles (cRGD/m) accumulated rapidly and had high permeability from vessels into the tumor parenchyma compared with the PM having nontargeted ligand, “cyclic-Arg-Ala-Asp” (cRAD). As both cRGD/m- and cRAD-linked polymeric micelles have similar characteristics, including their size, surface charge, and the amount of incorporated drugs, it is likely that the selective and accelerated accumulation of cRGD/m into tumors occurred via an active internalization pathway, possibly transcytosis, thereby producing significant antitumor effects in an orthotopic mouse model of U87MG human glioblastoma.
Firefly bioluminescence is broadly applied as a noninvasive imaging modality in the biomedical research field. One limitation in firefly bioluminescence imaging is the limited variety of luciferins ...emitting in the near-infrared (NIR) region (650–900 nm), where tissue penetration is high. Herein, we describe a series of structure-inherent NIR emitting firefly luciferin analogues, NIRLucs, designed through a ring fusion strategy. This strategy resulted in pH-independent structure-inherent NIR emission with a native firefly luciferase, which was theoretically supported by quantum chemical calculations of the oxidized form of each luciferin. When applied to cells, NIRLucs displayed dose-independent improved NIR emission even at low concentrations where the native d-luciferin substrate does not emit. Additionally, excellent blood retention and brighter photon flux (7-fold overall, 16-fold in the NIR spectral range) than in the case of d-luciferin have been observed with one of the NIRLucs in mice bearing subcutaneous tumors. We believe that these synthetic luciferins provide a solution to the longstanding limitation in the variety of NIR emitting luciferins and pave the way to the further development of NIR bioluminescence imaging platforms.
Stabilisation of fragile oligonucleotides, typically small interfering RNA (siRNA), is one of the most critical issues for oligonucleotide therapeutics. Many previous studies encapsulated ...oligonucleotides into ~100-nm nanoparticles. However, such nanoparticles inevitably accumulate in liver and spleen. Further, some intractable cancers, e.g., tumours in pancreas and brain, have inherent barrier characteristics preventing the penetration of such nanoparticles into tumour microenvironments. Herein, we report an alternative approach to cancer-targeted oligonucleotide delivery using a Y-shaped block catiomer (YBC) with precisely regulated chain length. Notably, the number of positive charges in YBC is adjusted to match that of negative charges in each oligonucleotide strand (i.e., 20). The YBC rendezvouses with a single oligonucleotide in the bloodstream to generate a dynamic ion-pair, termed unit polyion complex (uPIC). Owing to both significant longevity in the bloodstream and appreciably small size (~18 nm), the uPIC efficiently delivers oligonucleotides into pancreatic tumour and brain tumour models, exerting significant antitumour activity.
The design and construction of nanoreactors are important for biomedical applications of enzymes, but lipid‐ and polymeric‐vesicle‐based nanoreactors have some practical limitations. We have ...succeeded in preparing enzyme‐loaded polyion complex vesicles (PICsomes) through a facile protein‐loading method. The preservation of enzyme activity was confirmed even after cross‐linking of the PICsomes. The cross‐linked β‐galactosidase‐loaded PICsomes (β‐gal@PICsomes) selectively accumulated in the tumor tissue of mice. Moreover, a model prodrug, HMDER‐βGal, was successfully converted into a highly fluorescent product, HMDER, at the tumor site, even 4 days after administration of the β‐gal@PICsomes. Intravital confocal microscopy showed continuous production of HMDER and its distribution throughout the tumor tissues. Thus, enzyme‐loaded PICsomes are useful for prodrug activation at the tumor site and could be a versatile platform for enzyme delivery in enzyme prodrug therapy.
Fragile cargo: By vortex mixing, polyion complex vesicles (PICsomes) were readily loaded with enzymes, which were then delivered to tumor tissue without loss of enzyme activity. Importantly for future therapeutic applications as well as tumor imaging, the enzyme‐loaded PICsomes could be used to convert a model prodrug into a highly fluorescent product at the tumor site (see picture).
Nanocarriers responding to light have great potential for pinpoint therapy, and recent studies have revealed promising in vivo activity. However, light-selective gene transfer still remains ...challenging in the systemic application. Here we report systemic light-responsive nanocarriers for gene delivery developed through the sequential self-assembly of ABC-type triblock copolymer/DNA/dendrimeric photosensitizer, forming polyplex micelles with three-layered functional nanocompartments. The DNA-packaged core is covered by the photosensitizer-incorporated intermediate layer, which is encompassed by an outer shielding shell. This three-layered structure permits multistep photosensitizer and DNA delivery into a solid tumour by a systemic route: the shielding layer minimizes unfavourable interactions with blood components, and the photosensitizer is delivered to endo-/lysosomal membranes to facilitate light-selective cytoplasmic translocation of the micelles, accomplishing DNA delivery into the nucleus to exert gene expression. The polyplex micelles display >100-fold photoenhanced gene expression in cultured cells and exhibit light-induced in vivo gene transfer in solid tumours following systemic administration.
5‐Aminolevulinic acid (5‐ALA) is an amino acid that can be metabolized into a photosensitizer, protoporphyrin IX (PpIX) selectively in a tumor cell, permitting minimally invasive photodynamic ...diagnosis/therapy. However, some malignant tumor cells have excess intracellular labile iron and facilitate the conversion of PpIX into heme, which compromises the therapeutic potency of 5‐ALA. Here, we examined the potential of chelation of such unfavorable intratumoral labile iron in photodynamic therapy (PDT) with 5‐ALA hydrochloride, using polymeric iron chelators that we recently developed. The polymeric iron chelator efficiently inactivated the intracellular labile iron in cultured cancer cells and importantly enhanced the accumulation of PpIX, thereby improving the cytotoxicity upon photoirradiation. Even in in vivo study with subcutaneous tumor models, the polymeric iron chelator augmented the intratumoral accumulation of PpIX and the PDT effect. This study suggests that our polymeric iron chelator could be a tool for boosting the effect of 5‐ALA‐induced PDT by modulating tumor microenvironment.
Polymeric iron chelators efficiently inactivated the intracellular labile iron in cultured cancer cells and importantly enhanced the accumulation of 5‐aminolevulinic acid‐induced protoporphyrin IX, thereby improving the cytotoxicity upon photoirradiation. Even in in vivo study with subcutaneous tumor models, the polymeric iron chelator augmented the intratumoral accumulation of protoporphyrin IX and the effect of photodynamic therapy.
Lipid nanoparticles (LNPs) have been commonly used as a vehicle for nucleic acids, such as small interfering RNA (siRNA); the surface modification of LNPs is one of the determinants of their delivery ...efficiency especially in systemic administration. However, the applications of siRNA‐encapsulated LNPs are limited due to a lack effective systems to deliver to solid tumors. Here, we report a smart surface modification using a charge‐switchable ethylenediamine‐based polycarboxybetaine for enhancing tumor accumulation via interaction with anionic tumorous tissue constituents due to selective switching to cationic charge in response to cancerous acidic pH. Our polycarboxybetaine‐modified LNP could enhance cellular uptake in cancerous pH, resulting in facilitated endosomal escape and gene knockdown efficiency. After systemic administration, the polycarboxybetaine‐modified LNP accomplished high tumor accumulation in SKOV3‐luc and CT 26 subcutaneous tumor models. The siPLK‐1‐encapsulated LNP thereby accomplished significant tumor growth inhibition. This study demonstrates a promising potential of the pH‐responsive polycarboxybetaine as a material for modifying the surface of LNPs for efficient nucleic acid delivery.
Schematic illustration of DSPE‐PGlu(DET‐Car)30 and siRNA‐encapsulated PGlu(DET‐Car)30 LNPs
Fine-tuning of chemical structures of polycation-based carriers (polyplexes) is an attractive strategy for safe and efficient mRNA transfaction. Here, mRNA polyplexes comprising N-substituted ...polyaspartamides with varied numbers of side chain aminoethylene repeats were constructed, and their transfection ability against human hepatoma cells was examined. Transfection efficacy clearly correlated with the number of aminoethylene repeats: polyplexes with odd number repeats (PA-Os) produced sustained increases in mRNA expression compared with those with even number repeats (PA-Es). This predominant efficacy of PA-Os over PA-Es was contradictory to our previous findings for pDNA polyplexes prepared from the same N-substituted polyaspartamides, that is, PA-Es revealed superior transfection efficacy of pDNA than PA-Os. Intracellular FRET analysis using flow cytometry and polyplex tracking under confocal laser scanning microscopy revealed that overall transfection efficacy was determined through the balance between endosomal escaping capability and stability of translocated mRNA in cytoplasm. PA-Es efficiently transported mRNA into the cytoplasm. However, their poor cytoplasmic stability led to facile degradation of mRNA, resulting in a less durable pattern of transfection. Alternatively, PA-Os with limited capability of endosomal escape eventually protect mRNA in the cytoplasm to induce sustainable mRNA expression. Higher cytoplasmic stability of pDNA compared to mRNA may shift the limiting step in transfection from cytoplasmic stability to endosomal escape capacity, thereby giving an opposite odd–even effect in transfection efficacy. Endosomal escaping capability and nuclease stability of polyplexes are correlated with the modulated protonation behavior in aminoethylene repeats responding to pH, appealing the substantial importance of chemistry to design polycation structures for promoted mRNA transfection.
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