Targeting tumor microenvironment with PEG-based amphiphilic nanoparticles to overcome chemoresistance

Nanoemulsion Structural Design in Co-Encapsulation of Hybrid Multifunctional Agents: Influence of the Smart PLGA Polymers on the Nanosystem-Enhanced Delivery and Electro-Photodynamic Treatment

In the present study, we examined properties of poly(lactide-co-glycolide) (PLGA)-based nanocarriers (NCs) with various functional or “smart” properties, i.e., coated with PLGA, polyethylene glycolated PLGA (PEG-PLGA), or folic acid-functionalized PLGA (FA-PLGA). NCs were obtained by double emulsion (water-in-oil-in-water) evaporation process, which is one of the most suitable approaches in nanoemulsion structural design. Nanoemulsion surface engineering allowed us to co-encapsulate a hydrophobic porphyrin photosensitizing dye—verteporfin (VP) in combination with low-dose cisplatin (CisPt)—a hydrophilic cytostatic drug. The composition was tested as a multifunctional and synergistic hybrid agent for bioimaging and anticancer treatment assisted by electroporation on human ovarian cancer SKOV-3 and control hamster ovarian fibroblastoid CHO-K1 cell lines. The diameter of PLGA NCs with different coatings was on average 200 nm, as shown by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. We analyzed the effect of the nanocarrier charge and the polymeric shield variation on the colloidal stability using microelectrophoretic and turbidimetric methods. The cellular internalization and anticancer activity following the electro-photodynamic treatment (EP-PDT) were assessed with confocal microscopy and flow cytometry. Our data show that functionalized PLGA NCs are biocompatible and enable efficient delivery of the hybrid cargo to cancer cells, followed by enhanced killing of cells when supported by EP-PDT.

Gold Nanoparticles and Nanorods in Nuclear Medicine: A Mini Review

In the last decade, many innovative nanodrugs have been developed, as well as many nanoradiocompounds that show amazing features in nuclear imaging and/or radiometabolic therapy. Their potential uses offer a wide range of possibilities. It can be possible to develop nondimensional systems of existing radiopharmaceuticals or build engineered systems that combine a nanoparticle with the radiopharmaceutical, a tracer, and a target molecule, and still develop selective nanodetection systems. This review focuses on recent advances regarding the use of gold nanoparticles and nanorods in nuclear medicine. The up-to-date advancements will be shown concerning preparations with special attention on the dimensions and functionalizations that are most used to attain an enhanced performance of gold engineered nanomaterials. Many ideas are offered regarding recent in vitro and in vivo studies. Finally, the recent clinical trials and applications are discussed.

Folic Acid Receptor-Mediated Targeting Enhances the Cytotoxicity, Efficacy, and Selectivity of Withania somnifera Leaf Extract: In vitro and in vivo Evidence

Nanomedicine holds great potential for drug delivery to achieve more effective and safer cancer treatment. Earlier, we reported that the alcoholic extract of Withania somnifera leaves (i-Extract) has selective cancer cell killing activity. Herein, we developed a folate receptor-targeting i-Extract nanocomplex (FRi-ExNC) that suspends well in water and possesses enhanced selective anticancer activity in both in vitro and in vivo assays. Comparative analyses of folate receptor (FR)-positive and -negative cells revealed that FRi-ExNC caused a stronger decrease in Cyclin D/Cdk4 and anti-apoptotic protein Bcl-2, as well as a higher increase in the growth arrest regulating protein p21^WAF1 and pro-apoptotic protein PARP-1, in FR-enriched cancer cells. Our results demonstrate that FRi-ExNC could be a natural source-based nanomedicine for targeted cancer therapy.

Core-Shell Distinct Nanodrug Showing On-Demand Sequential Drug Release To Act on Multiple Cell Types for Synergistic Anticancer Therapy

Among various inflammatory factors/mediators, autocrine and paracrine prostaglandin 2 (PGE₂), which are abundant in various tumors, promote the proliferation and chemoresistance of cancer cells. Thus, eliminating the cytoprotective effect of PGE₂ may strengthen the antitumor effect of chemotherapy. Chemo/anti-inflammatory combination therapy requires the programmed activities of two different kinds of drugs that critically depend on their spatiotemporal manipulation inside the tumor. Here, a micellar polymeric nanosphere, encapsulating chemotherapeutic paclitaxel (PTX) in the core and conjugating anti-inflammatory celecoxib (CXB) to the shell through a peptide linker (PLGLAG), was developed. The PLGLAG linker was cleavable by the enzyme matrix metalloproteinase-2 (MMP-2) in the tumor tissue, causing CXB release and turning the negatively charged nanosphere into a positively charged one to facilitate PTX delivery into cancer cells. The released CXB not only acted on cyclooxygenase-2 (COX-2) to suppress the production of pro-inflammatory PGE₂ in multiple cell types but also suppressed the expression of the anti-apoptotic Bcl-2 gene to sensitize cancer cells to chemotherapy, thus resulting in a synergistic anticancer effect of PTX and CXB. This study represents an example of using a surface charge-switchable nanosphere with on-demand drug release properties to act on multiple cell types for highly effective chemo/anti-inflammatory combination therapy of cancer.

Biotin-functionalized copolymeric PEG-PCL micelles for in vivo tumour-targeted delivery of artemisinin

Artemisinin is used as an antimalarial and anticancer agent with minimal toxic effects on the host body. Biotin-PEG-PCL polymers have been used for targeted drug delivery to cancer, as well as to improve the pharmacokinetics of the drug and reduce its effects. In this study, biotin-conjugated copolymers were fabricated with polymerization of the ring opening method and the properties of copolymer and nanoparticles were investigated using various techniques. The toxicity of artemisinin and its nanoparticles have been investigated on MCF-7 and normal HFF2 cells. The results showed that the encapsulation efficacy of artemisinin in nanoparticles was 45.5 ± 0.41%. The release profile of the drug indicates that the release is slow and controlled and is approximately pH dependent. The results of artemisinin cell culture on human breast cancer cells showed that biotin-PEG-PCL nanoparticles had an inhibitory effect on MCF-7 cells and had no toxic effects on HFF2 cells. Anticancer activity in vivo in the 4T1 breast cancer model showed that tumour volumes were decreased up 40 mm³ by ART-loaded micelles and 76 mm³ by free ART, compared to the control group (2150 mm). In vivo results showed that this formulation significantly increases the accumulation of substances in the tumours. Therefore, the molecular formulation of ART-based copolymers can be a desirable process for cancer treatment purposes.

Organotropic drug delivery: Synthetic nanoparticles and extracellular vesicles

Most clinically approved drugs (primarily small molecules or antibodies) are rapidly cleared from circulation and distribute throughout the body. As a consequence, only a small portion of the dose accumulates at the target site, leading to low efficacy and adverse side effects. Therefore, new delivery strategies are necessary to increase organ and tissue-specific delivery of therapeutic agents. Nanoparticles provide a promising approach for prolonging the circulation time and improving the biodistribution of drugs. However, nanoparticles display several limitations, such as clearance by the immune systems and impaired diffusion in the tissue microenvironment. To overcome common nanoparticle limitations various functionalization and targeting strategies have been proposed. This review will discuss synthetic nanoparticle and extracellular vesicle delivery strategies that exploit organ-specific features to enhance drug accumulation at the target site.

Acidic pH and High-H2O2 Dual Tumor Microenvironment-Responsive Nanocatalytic Graphene Oxide for Cancer Selective Therapy and Recognition

It is well known that tumors have an acidic pH microenvironment and contain a high content of hydrogen peroxide (H₂O₂). These features of the tumor microenvironment may provide physiochemical conditions that are suitable for selective tumor therapy and recognition. Here, for the first time, we demonstrate that a type of graphene oxide nanoparticle (N-GO) can exhibit peroxidase-like activities (i.e., can increase the levels of reactive oxygen species (ROS)) under acidic conditions and catalyze the conversion of H₂O₂ to ROS-hydroxyl radicals (HO^·) in the acidic microenvironment in Hela tumors. The concentrated and highly toxic HO^· can then trigger necrosis of tumor cells. In the microenvironment of normal tissues, which has a neutral pH and low levels of H₂O₂, N-GOs exhibit catalase-like activity (scavenge ROS) that splits H₂O₂ into O₂ and water (H₂O), leaving normal cells unharmed. In the recognition of tumors, an inherent redox characteristic of dopamine is that it oxidizes to form dopamine-quinine under neutral (pH 7.4) conditions, quenching the fluorescence of N-GOs; however, this characteristic has no effect on the fluorescence of N-GOs in an acidic (pH 6.0) medium. This pH-controlled response provides an active targeting strategy for the diagnostic recognition of tumor cells. Our current work demonstrates that nanocatalytic N-GOs in an acidic and high-H₂O₂ tumor microenvironment can provide novel benefits that can reduce drug resistance, minimize side effects on normal tissues, improve antitumor efficacy, and offer good biocompatibility for tumor selective therapeutics and specific recognition.

Förster Resonance Energy Transfer-Activated Processes in Smart Nanotheranostics Fabricated in a Sustainable Manner

Multilayer nanocarriers loaded with optically activated payloads are gaining increasing attention due to their anticipated crucial role for providing new mechanisms of energy transfers in the health-oriented applications, as well as for energy storage and environmental protection. The combination of careful selection of optical components for efficient Förster resonance energy transfer, and surface engineering of the nanocarriers, allowed us to synthesize and characterize novel theranostic nanosystems for diagnosis and therapy of deep-seated tumors. The cargo, constrained within the oil core of the nanocapsules, composed of NaYF₄ :Tm⁺³ , Yb⁺³ up-converting nanoparticles together with a second-generation porphyrin-based photosensitizing agent-Verteporfin, assured requisite diagnostic and therapeutic functions under near-IR laser excitation. The outer polyaminoacid shell of the nanocapsules was functionalized with a ligand-poly(l-glutamic acid) functionalized by PEG-ylated folic acid-to ensure both a "stealth" effect and active targeting towards human breast cancer cells. The preparation criteria of all nanocarrier building blocks meet the requirements for sustainable and green chemistry practices. The multifunctionality of the proposed nanocarriers is a consequence of both the surface-functionalized organic exterior part, which was accessible for selective accumulation in cancer cells, and the hydrophobic optically active interior, which shows phototoxicity upon irradiation within the first biological window.

Synthesis and evaluation of the antiproliferative efficacy of BRM270 phytocomposite nanoparticles against human hepatoma cancer cell lines

BRM270 is the most leading phytochemical extract that possesses potent anticancer properties. A major challenge associated with this drug is its low bioavailability and thus requires high dosages for cancer treatment. Here, we report the novel nano-synthesis of phyto-composite, BRM270 for the first time by mechanical milling method with specific modifications for enhanced cytotoxicity against HepG2 human hepatoma cancer cells. Unlike free BRM270 and other phytomedicines, BRM270 nanoparticles (BRM270 NPs) are well-dispersed and small sized (23 to 70 nm) which is believed to greatly enhanced cellular uptake. Furthermore, the acidic tumor microenvironment attracts BRM270 NPs enhancing targeted therapy while leaving normal cells less affected. The comparative cytotoxicity analysis using MTT assay among the three treatment groups, such as free BRM270, BRM270 NPs, and doxorubicin demonstrated that BRM270 NPs induced greater cytotoxicity against HepG2 cells with an effective drug concentration of 12 μg/ml. From FACS analysis, we observed an apoptotic cell death of 44.4% at BRM270 NPs treated cells while only 12.5% found in the free BRM270 treated cells. Further, the comparative relative expression profiling of the candidate genes were showed significant (p < 0.05) down-regulation of IL6, BCL2, p53, and MMP9 in the BRM270 NPs treated cells, compared to the free BRM270 and doxorubicin. Indeed, the genes, CASPASE 9 and BAX have shown significant (p < 0.05) upregulation in cells treated with BRM270 NPs as compared to counter treatment groups. The investigation of the signal pathways and protein-protein network associations were also carried out to elucidate the functional insights underlying anti-cancer potential of BRM270 NPs in HepG2 cells. Taken together, our findings demonstrated that these uniquely engineered BRM270 NPs effectively enter into the cancer cells due to its acidic microenvironment thereby inducing apoptosis and regulate the cell-proliferation in-vitro at extremely low dosages.

Development of an interactive tumor vascular suppression strategy to inhibit multidrug resistance and metastasis with pH/H2O2 responsive and oxygen-producing nanohybrids

An ideal cancer therapeutic strategy should not only reverse multidrug resistance (MDR), but also prevent cancer metastasis. In this study, we address these cancer treatment challenges through an interactive vascular suppression strategy.

"Trojan Horse" DNA Nanostructure for Personalized Theranostics: Can It Knock on the Door of Preclinical Practice?

Nanotheranostics, combing diagnostic and therapeutic components in an all-in-one nanomaterial, possess exciting potentials for precision nanomedicine. However, a major obstacle for current nanotheranostics to enter preclinical and/or clinical trials is the intrinsic toxicities of these nanomaterials. As an emerging biomaterial, the bioinspired DNA nanostructure shows advantages for constructing better nanotheranostics due to its excellent features, including native biocompatibility, full programmability, and ready accessibility. In this feature article, we highlight recent advances in the design of DNA-nanostructure-based diagnostics and/or therapeutics capable of specifically responding to biological stimuli in a dynamic way, with a particular focus on the design mechanism, responsive performance, and potential for preclinical and/or clinical trials in personalized theranostics.

Fabrication of magnetic nanochains linked with CTX and curcumin for dual modal imaging detection and limitation of early tumour

OBJECTIVE

Five-year survival rate at early lung tumour was about 70%; however, its early diagnosis rate was still at a low level, so the enhancement of diagnosis level for early lung tumour is the key factor to increase the survival rate. Diagnosis and therapy of early lung tumour are still challenged.

METHODS

The magnetic nanochains (NCs) with biocompatibility and transverse relaxivity (r2  = 231 Fe mmol l-1  s-1 ) were fabricated through a co-precipitation method in the assistance of dextran, and then, linked with chlorotoxin (CTX) and curcumin (Cur) via the PEGylation and carbodiimide technique (named as CTX-NCs-Cur).

RESULTS

The results of cell test indicated that CTX-conjugated NCs could obviously target non-small-cell lung cancer cells and limit their growth. The in vivo results of magnetic resonance imaging and fluorescence imaging indicated that the CTX-NCs-Cur significantly targeted the tumour site and enhanced images contrast of the small-size tumour. Moreover, the results of everyday tail-vein injection confirmed that CTX-NCs-Cur could significantly limit the growth of early tumour, due to blocking Cl ion channels from CTX-NCs-Cur-MMP-2 composite and intracellular ROS increase from Cur treatment.

CONCLUSIONS

We provided a mechanism about the effect of CTX-NCs-Cur on the targeting and limiting early tumour, and these results indicated the application foreground of CTX-NCs-Cur in tumour diagnosis and therapy.

Curcumin in combination with anti-cancer drugs: A nanomedicine review

A huge surge of research is being conducted on combination therapy with anticancer compounds formulated in the form of nanoparticles (NPs). Numerous advantages like dose minimalization and synergism, reversal of multi drug resistance (MDRs), enhanced efficacy have emerged with nanoencapsulation of chemotherapeutic agents with chemo-sensitizing agent like curcumin. Within last couple of years various nano-sized formulations have been designed and tested both in vitro with cell lines for different types of cancers and in vivo with cancer types and drug resistance models. Despite the combinatorial models being advanced, translation to human trials has not been as smooth as one would have hoped, with as few as twenty ongoing clinical trials with curcumin combination, with less than 1/10th being nano-particulate formulations. Mass production of nano-formulation based on their physico-chemical and pharmacokinetics deficits poses as major hurdle up the ladder. Combination of these nano-sized dosage with poorly bioavailable drugs, unspecific target binding ability and naturally unstable curcumin further complicates the formulation aspects. Emphasis is now therefore being laid on altering natural forms of curcumin and usage of formulations like prodrug or coating of curcumin to overcome stability issues and focus more on enhancing the pharmaceutical and therapeutic ability of the nano-composites. Current studies and futuristic outlook in this direction are discussed in the review, which can serve as the basis for upcoming research which could boost commercial translational of improved nano-sized curcumin combination chemotherapy.

Tumor Microenvironment Targeted Nanotherapy

Recent developments in nanotechnology have brought new approaches to cancer diagnosis and therapy. While enhanced permeability and retention effect promotes nano-chemotherapeutics extravasation, the abnormal tumor vasculature, high interstitial pressure and dense stroma structure limit homogeneous intratumoral distribution of nano-chemotherapeutics and compromise their imaging and therapeutic effect. Moreover, heterogeneous distribution of nano-chemotherapeutics in non-tumor-stroma cells damages the non-tumor cells, and interferes with tumor-stroma crosstalk. This can lead not only to inhibition of tumor progression, but can also paradoxically induce acquired resistance and facilitate tumor cell proliferation and metastasis. Overall, the tumor microenvironment plays a vital role in regulating nano-chemotherapeutics distribution and their biological effects. In this review, the barriers in tumor microenvironment, its consequential effects on nano-chemotherapeutics, considerations to improve nano-chemotherapeutics delivery and combinatory strategies to overcome acquired resistance induced by tumor microenvironment have been summarized. The various strategies viz., nanotechnology based approach as well as ligand-mediated, redox-responsive, and enzyme-mediated based combinatorial nanoapproaches have been discussed in this review.

An overview of nanoscale radionuclides and radiolabeled nanomaterials commonly used for nuclear molecular imaging and therapeutic functions

Recent advances in the field of nanotechnology applications in nuclear medicine offer the promise of better diagnostic and therapeutic options. In recent years, increasing efforts have been focused on developing nanoconstructs that can be used as core platforms for attaching medical radionuclides with different strategies for the purposes of molecular imaging and targeted drug delivery. This review article presents an introduction to some commonly used nanomaterials with zero-dimensional, one-dimensional, two-dimensional, and three-dimensional structures, describes the various methods applied to radiolabeling of nanomaterials, and provides illustrative examples of application of the nanoscale radionuclides or radiolabeled nanocarriers in nuclear nanomedicine. Especially, the passive and active nanotargeting delivery of radionuclides with illustrating examples for tumor imaging and therapy was reviewed and summarized. The accurate and early diagnosis of cancer can lead to increased survival rates for different types of this disease. Although, the conventional single-modality diagnostic methods such as positron emission tomography/single photon emission computed tomography or MRI used for such purposes are powerful means; most of these are limited by sensitivity or resolution. By integrating complementary signal reporters into a single nanoparticulate contrast agent, multimodal molecular imaging can be performed as scalable images with high sensitivity, resolution, and specificity. The advent of radiolabeled nanocarriers or radioisotope-loaded nanomaterials with magnetic, plasmonic, or fluorescent properties has stimulated growing interest in the developing multimodality imaging probes. These new developments in nuclear nanomedicine are expected to introduce a paradigm shift in multimodal molecular imaging and thereby opening up an era of new diagnostic medical imaging agents. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 251-285, 2019.

Endothelial growth factor receptor-targeted and reactive oxygen species-responsive lung cancer therapy by docetaxel and resveratrol encapsulated lipid-polymer hybrid nanoparticles

Special targeted therapy like endothelial growth factor receptor (EGFR) targeted therapy is available for the treatment of advanced non-small cell lung cancer (NSCLC). Biodegradable core-shell lipid-polymer hybrid nanoparticles (LPNs) can combine the beneficial properties of lipid and polymeric NPs for controlled drug delivery. In the present study, epidermal growth factor (EGF) conjugated LPNs were fabricated to co-deliver docetaxel (DTX) and resveratrol (RSV). In vitro and in vivo studies demonstrated that EGF DTX/RSV LPNs have significant synergistic effects, best tumor inhibition ability and the lowest systemic toxicity. The results indicate that EGF DTX/RSV LPNs may be a promising strategy for treatment of NSCLC.

MiR-31 regulates the cisplatin resistance by targeting Src in gallbladder cancer

Background

Gallbladder cancer (GBC) is a malignant tumor highly resistant to chemotherapy. MicroRNAs (miRNAs) are found extensively involved in modulation of carcinogenesis and chemoresistance. This study aimed to investigate cisplatin (DDP)-susceptibility regulated by expression of the miRNAs and underlying pathways in GBC.

Results

The microRNA-31 (miR-31) was selected by microarray due to the biggest fold change between DDP-resistant and parental cells. Ectopic overexpression of miR-31 decreased cell proliferation, viability and invasion capacity, but promoted apoptosis in DDP-resistant cells and in xenograft tumor models. Cell apoptosis and DDP-chemosensitivity was remarkably increased by knockdown of Src proto-oncogene (Src) expression, which was subsequently reversed by rescue of Src expression in miR-31-expressing cells.

Methods

The microarray was used to select the candidate miRNA in two DDP-resistant GBC cell lines. The effect of regulated expression of the miRNA on cell migration, invasion, proliferation and apoptosis was examined by wound healing, transwell assays, CCK-8 assays, colony formation and flow cytometry assays, respectively. Xenograft tumor models were used to validate the function of the downstream target.

Conclusion

Our results demonstrated that miR-31reduced significantly in GBC cells rendering resistance to cisplatin, and upregulated expression of miR-31 augmented chemosensitivity, presenting a therapeutic potential to overcome drug resistance in GBC.

Co-delivery of Vorinostat and Etoposide Via Disulfide Cross-Linked Biodegradable Polymeric Nanogels: Synthesis, Characterization, Biodegradation, and Anticancer Activity

Treatment regimens for cancer patients using single chemotherapeutic agents often lead to undesirable toxicity, drug resistance, reduced uptake etc. Combination of two or more drugs is therefore becoming an imperative strategy to overcome these limitations. A step forward can be taken through delivery of the drugs used in combination via nanoparticles. Co-administration of chemotherapeutic drugs encapsulated in nanoparticles has been shown to result in synergistic effects and enhanced therapeutic efficacy. In present study, we explored the combination treatment of histone deacetylase inhibitor vorinostat (VOR) and topoisomerase II inhibitor etoposide (ETOP). The concurrent combination treatment of VOR and ETOP resulted in synergistic effect on human cervical HeLa cancer cells. VOR and ETOP were encapsulated into poly(ethylene glycol) monomethacrylate (POEOMA)-based disulfide cross-linked nanogels. The nanogels were synthesized using atom transfer radical polymerization (ATRP) via cyclohexane/water inverse mini-emulsion and were degradable in presence of intracellular glutathione (GSH) concentration. Both the drugs were loaded into the nanogels by physical encapsulation method and characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and differential scanning calorimetry (DSC). Both VOR- and ETOP-loaded nanogels showed sustained release profile. Furthermore, combination treatment drugs encapsulated of POEOMA nanogel demonstrated enhanced synergistic cytotoxic effect compared with combination of free drugs. Enhanced synergistic cell killing efficiency of drug-loaded POEOMA nanogels was due to increased apoptosis via caspase 3/7 activation. Therefore, combination of VOR- and ETOP-loaded PEG-based biodegradable nanogels may provide a promising therapy with enhanced anticancer effect.

Stimuli-Responsive Nanomedicines for Overcoming Cancer Multidrug Resistance

Chemotherapy is still a main option for cancer therapy, but its efficacy is often unsatisfying due to multidrug resistance (MDR). The tumor microenvironment is considered a dominant factor causing MDR. Stimuli-responsive nanomedicines exhibit many superiorities for reversal of MDR. As smart systems, stimuli-responsive nanomedicines are desirable for achieving site-specific accumulation and triggered drug release in response to slight changes in physicochemical properties in pathological conditions or to exogenous stimuli. In this review, we highlight the current progress of various nanomedicines with different stimuli-responsive capabilities for overcoming MDR. The materials, design, construction as well as efficacy in overcoming MDR of these nanomedicines are discussed. Eventually, we look forward to forthcoming intelligent nanoparticle systems with new mechanisms to deliver drugs for practical applications in conquering cancer MDR.

Smart pH-sensitive nanoassemblies with cleavable PEGylation for tumor targeted drug delivery

A new acidly sensitive PEGylated polyethylenimine linked by Schiff base (PEG-s-PEI) was designed to render pH-sensitive PEGylation nanoassemblies through multiple interactions with indomethacin and docetaxel (DTX). DTX nanoassemblies driven by PEG-s-PEI thus formulated exhibited an excellent pH-sensitivity PEGylation cleavage performance at extracellular pH of tumor microenvironment, compared to normal tissues, thereby long circulated in blood but were highly phagocytosed by tumor cells. Consequently, this smart pH-sensitive PEGylation cleavage provided an efficient strategy to target tumor microenvironment, in turn afforded superior therapeutic outcome in anti-tumor activity.

Polyphosphoester-Camptothecin Prodrug with Reduction-Response Prepared via Michael Addition Polymerization and Click Reaction

Polyphosphoesters (PPEs), as potential candidates for biocompatible and biodegradable polymers, play an important role in material science. Various synthetic methods have been employed in the preparation of PPEs such as polycondensation, polyaddition, ring-opening polymerization, and olefin metathesis polymerization. In this study, a series of linear PPEs has been prepared via one-step Michael addition polymerization. Subsequently, camptothecin (CPT) derivatives containing disulfide bonds and azido groups were linked onto the side chain of the PPE through Cu(I)-catalyzed azidealkyne cyclo-addition "click" chemistry to yield a reduction-responsive polymeric prodrug P(EAEP-PPA)-g-ss-CPT. The chemical structures were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared, ultraviolet-visible spectrophotometer, and high performance liquid chromatograph analyses, respectively. The amphiphilic prodrug could self-assemble into micelles in aqueous solution. The average particle size and morphology of the prodrug micelles were measured by dynamic light scattering and transmission electron microscopy, respectively. The results of size change under different conditions indicate that the micelles possess a favorable stability in physiological conditions and can be degraded in reductive medium. Moreover, the studies of in vitro drug release behavior confirm the reduction-responsive degradation of the prodrug micelles. A methyl thiazolyl tetrazolium assay verifies the good biocompatibility of P(EAEP-PPA) not only for normal cells, but also for tumor cells. The results of cytotoxicity and the intracellular uptake about prodrug micelles further demonstrate that the prodrug micelles can efficiently release CPT into 4T1 or HepG2 cells to inhibit the cell proliferation. All these results show that the polyphosphoester-based prodrug can be used for triggered drug delivery system in cancer treatment.

Multifunctional Nanoparticles Loading with Docetaxel and GDC0941 for Reversing Multidrug Resistance Mediated by PI3K/Akt Signal Pathway

The polylactic-co-glycolic acid polyethylene glycol conjugated with cell penetrating peptide R₇ (PLGA-PEG-R₇)/polysulfadimethoxine-folate nanoparticles loaded with docetaxel (DTX) and GDC0941 (R₇/PSD-Fol NPs) were prepared to overcome multidrug resistance (MDR) and enhance the antitumor activity. First, polysulfadimethoxine-folate was synthesized to construct the R₇/PSD-Fol NPs. The R₇/PSD-Fol NPs were prepared with the abilities of effective entrapment and drug loading. Due to the pH-sensitive effect of PSD-folate, the releasing of DTX and GDC0941 from the R₇/PSD-Fol NPs was lower in pH 7.4 buffer solution than that in pH 5.0 buffer solution. The half maximal inhibitory concentration (IC₅₀) of MCF-7 and resistant to doxorubicin (MCF-7/Adr) cells illustrated the cytotoxicity of R₇/PSD-Fol nanoparticles by using the MTT method. The uptake of R₇/PSD-Fol NPs was visualized by using the fluorescence of Rh-123 to detect the targeting effect of folate on the surface of R₇/PSD-Fol NPs. The results of the cell apoptosis and the depolarization of mitochondrial membrane potential (MMP) were adopted to show the cytotoxicity of the R₇/PSD-Fol NPs on MCF-7/Adr cells. The Western blot revealed the inhibition of PI3K/Akt pathway in MCF-7/Adr cells induced by R₇/PSD-Fol NPs. Finally, both in vivo distribution and in vivo antitumor showed the R₇/PSD-Fol NPs displayed the better distribution at tumor site and the stronger suppression of tumor growth in the tumor bearing nude mice compared with control group. It was concluded that R₇/PSD-Fol NPs loaded with DTX and GDC0941 could overcome MDR and enhance the antitumor effect further.

Transferrin receptor-targeted pH-sensitive micellar system for diminution of drug resistance and targetable delivery in multidrug-resistant breast cancer

The emergence of drug resistance is partially associated with overproduction of transferrin receptor (TfR). To overcome multidrug resistance (MDR) and achieve tumor target delivery, we designed a novel biodegradable pH-sensitive micellar system modified with HAIYPRH, a TfR ligand (7pep). First, the polymers poly(l-histidine)-coupled polyethylene glycol-2000 (PHIS-PEG₂₀₀₀) and 7pep-modified 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol-2000 (7pep-DSPE-PEG₂₀₀₀) were synthesized, and the mixed micelles were prepared by blending of PHIS-PEG₂₀₀₀ and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol-2000 (DSPE-PEG₂₀₀₀) or 7pep-DSPE-PEG₂₀₀₀ (7-pep HD micelles). The micelles exhibited good size uniformity, high encapsulation efficiency, and a low critical micelle concentration. By changing the polymer ratio in the micellar formulation, the pH response range was specially tailored to pH ~6.0. When loaded with antitumor drug doxorubicin (DOX), the micelle showed an acid pH-triggering drug release profile. The cellular uptake and cytotoxicity study demonstrated that 7-pep HD micelles could significantly enhance the intracellular level and antitumor efficacy of DOX in multidrug-resistant cells (MCF-7/Adr), which attributed to the synergistic effect of poly(l-histidine)-triggered endolysosom escape and TfR-mediated endocytosis. Most importantly, the in vivo imaging study confirmed the target-ability of 7-pep HD micelles to MDR tumor. These findings indicated that 7-pep HD micelles would be a promising drug delivery system in the treatment of drug-resistant tumors.

Co-delivery of doxorubicin and pH-sensitive curcumin prodrug by transferrin-targeted nanoparticles for breast cancer treatment

The natural product curcumin and the chemotherapeutic agent doxorubicin have been used in the treatment of many cancers, including breast cancer. However, fast clearance and unspecific distribution in the body after intravenous injection are still challenges to be overcome by an ideal nano-sized drug delivery system in cancer treatment. In this study we design transferrin (Tf) decorated nanoparticles (NPs) to co-deliver CUR and DOX for breast cancer treatment. A pH-sensitive prodrug, transferrin-poly(ethylene glycol)-curcumin (Tf-PEG-CUR), was synthesized and used for the self‑assembling of NPs (Tf-PEG-CUR NPs). DOX is incorporated into the Tf-PEG-CUR NPs to obtain Tf-PEG-CUR/DOX NPs. In vitro cytotoxicity studies and in vivo antitumor activity were carried out using MCF-7 cells and mice bearing MCF-7 cells, respectively. Tf-PEG-CUR/DOX NPs has a particle size of 89 nm and a zeta potential of -15.6 mV. This system displayed remarkably higher efficiency than other systems both in vitro and in vivo. DOX and CUR were successfully loaded into nanocarriers. The in vitro cell viability assays revealed the combination of Tf-PEG-CUR and DOX NPs exhibited higher cytotoxicity in vitro in MCF-7 cells compared with Tf-PEG-CUR NPs alone. Using the breast cancer xenograft mouse model, we demonstrate that this co-encapsulation approach resulted in an efficient tumor-targeted drug delivery, decreased cytotoxic effects and exhibited stronger antitumor effect.

In vivo biodistribution and passive accumulation of upconversion nanoparticles in colorectal cancer models via intraperitoneal injection

Cit-UCNPs after IP injection exhibited significantly different biological processes from those after IV injection. The passive-tumour targeting effectiveness of cit-UCNPs via the IP route was higher than that via the IV route.

Aptamer-functionalized peptide H3CR5C as a novel nanovehicle for codelivery of fasudil and miRNA-195 targeting hepatocellular carcinoma

Liver cancer is the fifth most commonly diagnosed malignancy, of which hepatocellular carcinoma (HCC) represents the dominating histological subtype. Antiangiogenic therapy aimed at vascular endothelial growth factor (VEGF) has shown promising but deficient clinical prospects on account of vasculogenic mimicry, a highly patterned vascular channel distinguished from the endothelium-dependent blood vessel, which may function as blood supply networks occurring in aggressive tumors including HCC. In this study, we used a new cationic peptide, disulfide cross-linked stearylated polyarginine peptide modified with histidine (H3R5), as a reducible vector, cell penetrating peptide-modified aptamer (ST21) with specific binding to HCC cells to conjugate to peptide H3R5 as the targeting probe, miRNA-195 (miR195) as a powerful gene drug to inhibit VEGF, and fasudil to suppress vasculogenic mimicry by blocking ROCK2, all of which were simultaneously encapsulated in the same nanoparticles. Fasudil was loaded by ammonium sulfate-induced transmembrane electrochemical gradient and miR195 was condensed through electrostatic interaction. ST21-H3R5-polyethylene glycol (PEG) exhibited excellent loading capacities for both fasudil and miR195 with adjustable dosing ratios. Western blot analysis showed that (Fasudil)ST21-H3R5-PEGmiR195 had strong silencing activity of ROCK2 and VEGF, as compared with (Fasudil)H3R5-PEGmiR195. In vitro and in vivo experiments confirmed that ST21-modified nanoparticles showed significantly higher cellular uptake and therapeutic efficacy in tumor cells or tumor tissues than the unmodified counterparts. These findings suggest that aptamer-conjugated peptide holds great promise for delivering chemical drugs and gene drugs simultaneously to overcome HCC.

Soft Interaction in Liposome Nanocarriers for Therapeutic Drug Delivery

The development of smart nanocarriers for the delivery of therapeutic drugs has experienced considerable expansion in recent decades, with the development of new medicines devoted to cancer treatment. In this respect a wide range of strategies can be developed by employing liposome nanocarriers with desired physico-chemical properties that, by exploiting a combination of a number of suitable soft interactions, can facilitate the transit through the biological barriers from the point of administration up to the site of drug action. As a result, the materials engineer has generated through the bottom up approach a variety of supramolecular nanocarriers for the encapsulation and controlled delivery of therapeutics which have revealed beneficial developments for stabilizing drug compounds, overcoming impediments to cellular and tissue uptake, and improving biodistribution of therapeutic compounds to target sites. Herein we present recent advances in liposome drug delivery by analyzing the main structural features of liposome nanocarriers which strongly influence their interaction in solution. More specifically, we will focus on the analysis of the relevant soft interactions involved in drug delivery processes which are responsible of main behaviour of soft nanocarriers in complex physiological fluids. Investigation of the interaction between liposomes at the molecular level can be considered an important platform for the modeling of the molecular recognition processes occurring between cells. Some relevant strategies to overcome the biological barriers during the drug delivery of the nanocarriers are presented which outline the main structure-properties relationships as well as their advantages (and drawbacks) in therapeutic and biomedical applications.