Diversity Oriented Synthesis of Novel Xanthones Reveal Potent Doxorubicin-Inspired Analogs.

Inspired by potent antiproliferative xanthone natural products and so far limited examples of derived bioactive agents, a structure activity study of architecturally novel types of xanthones is reported. Their preparation was enabled in a short and divergent manner by a modular chlorination in combination with optimized protocols for a polar condensation and a hetero-cyclization. Application of these procedures allowed for the synthesis of various polyhalogenated representatives (including mixed bromo/chloro xanthones) that were obtained in up to fourfold improved yields as compared to previous procedures. Subsequent Suzuki coupling of either halide enabled access to phenyl- and chloro-bearing xanthones, which may be functionalized at four out of five non-hydroxylated positions. Antiproliferative assays against breast cancer cell lines revealed potent activities of some of these simplified analogs that are in the range of pharmaceutically used anticancer drug doxorubicin.

Enhanced Anti-Tumor Effect of Folate-Targeted FA-AMA-hyd-DOX Conjugate in a Xenograft Model of Human Breast Cancer.

Folate-aminocaproic acid-doxorubicin (FA-AMA-hyd-DOX) was firstly synthesized by our group. It was indicated that FA-AMA-hyd-DOX was pH-responsive, and had strong cytotoxicity on a folate receptor overexpressing cell line (KB cells) in vitro. The aim of our study was to further explore the potential use of FA-AMA-hyd-DOX as a new therapeutic drug for breast cancer. The cellular uptake and the antiproliferative activity of the FA-AMA-hyd-DOX in MDA-MB-231 cells were measured. Compared with DOX, FA-AMA-hyd-DOX exhibited higher targeting ability and cytotoxicity to FR-positive tumor cells. Subsequently, the tissue distribution of FA-AMA-hyd-DOX was studied, and the result confirmed that DOX modified by FA can effectively increase the selectivity of drugs in vivo. After determining the maximum tolerated dose (MTD) of FA-AMA-hyd-DOX in MDA-MB-231 tumor-bearing nude mice, the antitumor effects and the in vivo safety of FA-AMA-hyd-DOX were systematically evaluated. The data showed that FA-AMA-hyd-DOX could effectively increase the dose of DOX tolerated by tumor-bearing nude mice and significantly inhibit MDA-MB-231 tumor growth in vivo. Furthermore, FA-AMA-hyd-DOX treatment resulted in almost no obvious damage to the mice. All the positive data suggest that FA-targeted FA-AMA-hyd-DOX is a promising tumor-targeted compound for breast cancer therapy.

Drug development of lyso-thermosensitive liposomal doxorubicin: Combining hyperthermia and thermosensitive drug delivery.

We review the drug development of lyso-thermosensitive liposomal doxorubicin (LTLD) which is the first heat-activated formulation of a liposomal drug carrier to be utilized in human clinical trials. This class of compounds is designed to carry a payload of a cytotoxic agent and adequately circulate in order to accumulate at a tumor that is being heated. At the target the carrier is activated by heat and releases its contents at high concentrations. We summarize the preclinical and clinical experience of LTLD including its successes and challenges in the development process.

EGFR-targeted prodrug activation using bioorthogonal alkene-azide click-and-release chemistry.

Epidermal growth factor receptor (EGFR) is overexpressed in many cancers and therefore serves as an excellent target for prodrug activation. Functionalised trans-cyclooctenes (TCO) were conjugated to an EGFR antibody (cetuximab), providing a reagent for pre-targeting and localisation of the bioorthogonal reagent. The TCOs react with a 4-azidobenzyl carbamate doxorubicin prodrug via a [3 + 2]-cycloaddition and subsequent self-immolation leads to release of doxorubicin (click-and-release). In vitro cell-based assays demonstrated proof-of-concept, that cetuximab conjugated to highly strained TCO (AB-d-TCO) could bind to the EGFR in a melanoma cell line, and selectively activate the doxorubicin prodrug. In a non-EGFR expressing melanoma cell line, no significant prodrug activation was observed. In vivo experiments using this combination of AB-d-TCO and the azido-doxorubicin prodrug in a murine melanoma model revealed no significant anti-tumour activity or increased survival, suggesting there was insufficient prodrug activation and drug release at the tumour site.

Iridium-Triggered Allylcarbamate Uncaging in Living Cells.

Designing a metal catalyst that addresses the major issues of solubility, stability, toxicity, cell uptake, and reactivity within complex biological milieu for bioorthogonal controlled transformation reactions is a highly formidable challenge. Herein, we report an organoiridium complex that is nontoxic and capable of the uncaging of allyloxycarbonyl-protected amines under biologically relevant conditions and within living cells. The potential applications of this uncaging chemistry have been demonstrated by the generation of diagnostic and therapeutic agents upon the activation of profluorophore and prodrug in a controlled fashion within HeLa cells, providing a valuable tool for numerous potential biological and therapeutic applications.

Efficient Design to Monitor the Site-specific Sustained Release of a Non-Emissive Anticancer Drug.

A pH-responsive smart nanocarrier with significant components was synthesized by conjugating the non-emissive anticancer drug methyl orange and polyethylene glycol derived folate moiety to the backbone of polynorbornene. Complete synthesis procedure and characterization methods of three monomers included in the work: norbornene-derived Chlorambucil (Monomer 1), norbornene grafted with polyethylene glycol, and folic acid (Monomer 2) and norbornene attached methyl orange (Monomer 3) connected to the norbornene backbone through ester linkage were clearly discussed. Finally, the random copolymer CHO PEG FOL METH was synthesized by ring-opening metathesis polymerization (ROMP) using Grubbs' second-generation catalyst. Advanced polymer chromatography (APC) was used to find the final polymer's molecular weight and polydispersity index (PDI). Dynamic light scattering, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were utilized to explore the prodrug's size and morphology. Release experiments of the anticancer drug, Chlorambucil and the coloring agent, methyl orange, were performed at different pH and time. Cell viability assay was carried out for determining the rate of survived cells, followed by the treatment of our final polymer named CHO PEG FOL METH.

Glucose oxidase loaded Cu2+ based metal-organic framework for glutathione depletion/reactive oxygen species elevation enhanced chemotherapy.

INTRODUCTION: The development of multidrug resistance (MDR) is a major cause for the failure of chemotherapy, which requires the aid of nanomedicine. METHODS: Here in our study, a Cu2+ based metal-organic framework (COF) was firstly developed and employed as a carrier for the delivery of glucose oxidase (GOx) and doxorubicin (Dox) (COF/GOx/Dox) for the therapy of MDR lung cancers. RESULTS: Our results showed that the GOx can catalyze glucose and produce H2O2. In the mean time, the Cu2+ can react with GSH and then transform into Cu+, which resulted in GSH depletion. Afterwards, the produced Cu+ and H2O2 trigger Fenton reaction to generate ROS to damage the redox equilibrium of cancer cells. Both effects contributed to the reverse of MDR in A549/Dox cells and finally resulted in significantly enhanced in vitro/in vivo anticancer performance. DISCUSSION: The combination of glutathione depletion/reactive oxygen species elevation might be a promising strategy to enhance the efficacy of chemotherapy and reverse MDR in cancers.

One Pot Green Synthesis of Doxorubicin and Curcumin Loaded Magnetic Nanoparticles and Cytotoxicity Studies.

BACKGROUND: Green synthesis, an alternative method for synthesizing nanoparticles, is cheaper, environmentally friendly, and does not show toxic effects. Doxorubicin is a chemotherapeutic agent used in lung cancer. Curcumin is a bioactive compound with properties, such as an anticancer obtained from Curcuma longa. OBJECTIVE: The objective of this study was to develop Doxorubicin and Curcumin loaded magnetic nanoparticles that could be synthesized by green tea leaves and to investigate cytotoxic effects against the A549-luc-C8, non-small cell lung cancer line. METHODS: Magnetic nanoparticles were synthesized with the green synthesis method. Furthermore, Doxorubicin and Curcumin were encapsulated into magnetic nanoparticles with the one-pot method and obtained magnetic nanoparticles characterized using FTIR, SEM/EDX, XRD, and UV-VIS spectrophotometric techniques. After that, The drug release test was performed by dialysis using pH 7.4 phosphate-buffered saline at 37 °C. MTT assay was performed to test the cytotoxicity effect in the A549-luc-C8 cell line. RESULTS: FTIR analysis verified the magnetic structure and drug loading. SEM images of magnetic nanoparticle revealed that they had a size of about 50-60 nm in a mono-disperse manner. Drug release after 24 h was found to be 5.8% for doxorubicin and 3.4% for curcumin, showing controlled release. CONCLUSION: Results showed that the prepared magnetic nanoparticles had a synergistic antitumor activity for A549-luc-C8.

The Synthesis of Nano-Doxorubicin and its Anticancer Effect.

Doxorubicin (DOX) is widely used as a clinical first-line anti-cancer drug. However, its clinical application is severely limited due to the lack of tumor specificity of the drug and severe side effects such as myelosuppression, nephrotoxicity, dose-dependent cardiotoxicity, and multi-drug resistance. To improve the bioavailability of DOX, maximize the therapeutic effect, and reduce its toxicity and side effects, many studies have been done on the nanoformulations of DOX, such as liposomes, polymer micelles, dendrimer, and nanogels. Herein, we review the latest progress of DOX nano-preparations and their anti-tumor effects, hoping to provide theoretical references and new research ideas for the development of new dosage forms of the drug and the technical methods available for clinical application.

Endogenous mRNA Triggered DNA-Au Nanomachine for In Situ Imaging and Targeted Multimodal Synergistic Cancer Therapy.

The development of versatile nanotheranostic platforms that integrate both diagnostic and therapeutic functions have always been an intractable challenge in precise cancer treatment. Herein, an aptamer-tethered deoxyribonucleic acids-gold particle (Apt-DNA-Au) nanomachine has been developed for in situ imaging and targeted multimodal synergistic therapy of mammary carcinoma. Upon specifically internalized into MCF-7 cells, the tumor-related TK1 mRNA activates the Apt-DNA-Au nanomachine by DNA strand displacement cascades, resulting in the release of the fluorophore and antisense DNA as well as the aggregation of AuNPs for in situ imaging, suppression of survivin expression and photothermal therapy, respectively. Meanwhile, the controlled released drugs are used for chemotherapy, while under the laser irradiation the loaded photosensitizer produces reactive oxygen species (ROS) for photodynamic therapy. The results confirm that the proposed Apt-DNA-Au nanomachine provides a powerful nanotheranostic platform for in situ imaging-guided combinatorial anticancer therapy.

Construction and research on size and phase 'fixed-point remodelling' intelligent drug delivery system.

It is important to enhance penetration depth of nanomedicine and realise rapid drug release simultaneously at targeted tumour for improving anti-tumour efficiency of chemotherapeutic drugs. This project employed sodium alginate (Alg) as matrix material, to establish tumour-responsive nanogels with particle size conversion and drug controlled release functions. Specifically, tumour-targeting peptide CRGDK was conjugated with Alg first (CRGDK-Alg). Then, doxorubicin (DOX) was efficiently encapsulated in CRGDK-FeAlg nanogel during the cross-linking process (CRGDK-FeAlg/DOX). This system was closed during circulation. Once reaching tumour, the particle size of nanogels was reduced to ∼25 nm, which facilitated deep penetration of DOX in tumour tissues. After entering tumour cells, the size of nanogels was further reduced to ∼10 nm and DOX was released simultaneously. Meanwhile, FeAlg efficiently catalysed H2O2 to produce •OH by Fenton reaction, achieving local chemodynamic therapy without O2 mediation. Results showed CRGDK-FeAlg/DOX significantly inhibited tumour proliferation in vivo with V/V0 of 1.13 after treatment, significantly lower than that of control group with V/V0 of 4.79.

Low-Dose X-ray-Responsive Diselenide Nanocarriers for Effective Delivery of Anticancer Agents.

X-ray-responsive nanocarriers for anticancer drug delivery have shown great promise for enhancing the efficacy of chemoradiotherapy. A critical challenge remains for development of such radiation-controlled drug delivery systems (DDSs), which is to minimize the required X-ray dose for triggering the cargo release. Herein, we design and fabricate an effective DDS based on diselenide block copolymers (as nanocarrier), which can be triggered to release their cargo with a reduced radiation dose of 2 Gy due to their sensitivity to both X-ray and the high level of reactive oxygen species (ROS) in the microenvironment of cancer cells. The underlying molecular mechanism is further illustrated by proton nuclear magnetic resonance (1H NMR) experiments and density functional theory (DFT) calculations. In vivo experiments on tumor-bearing mice validated that the loaded drugs are effectively delivered to the tumor site and exert remarkable antitumor effects (minimum tumor volume/weight) along with X-ray. Furthermore, the diselenide nanocarriers exhibit no noticeable cytotoxicity. These findings provide new insights for the de novo design of radiation-controlled DDSs for cancer chemoradiotherapy.

One molecule two goals: A selective P-glycoprotein modulator increases drug transport across gastro-intestinal barrier and recovers doxorubicin toxicity in multidrug resistant cancer cells.

In the present study a series of tetrahydroisoquinoline derivatives were synthesized and evaluated for their activity towards three ABC transporters, P-gp, MRP1 and BCRP. The compounds proved to be selective against P-gp. One of them, 8b, displayed activity in the nanomolar range (EC50 = 94 nM). Thus, compound 8b was tested for its ability to restore the cytotoxic activity of a well-known anti-cancer agent and P-gp substrate, doxorubicin, as first proof of concept. Moreover, compound 8b was also tested in an in vitro model of competent gastro-intestinal (GI) barrier (Caco-2 cells) for its ability to inhibit P-gp, present on luminal side, and increase the apical-to-basolateral transport of several structurally uncorrelated drugs, belonging to different therapeutic areas but actively excreted by P-gp. Notably the transport of the drugs across the GI barrier was increased by a concentration of 8b devoid of toxicity and of perturbing effects on barrier function. An in vitro simulated digestion process was set up: interestingly the effect of 8b on the transport of digoxin was preserved also after the simulated digestion process. This result may suggest 8b as a safe and effective P-gp modulator that can increase the bioavailability of a wide spectrum of drugs administered per os, improving their transport across the GI barrier.

Evaluation of PNU-159682 antibody drug conjugates (ADCs).

PNU-159682 is a highly potent secondary metabolite of nemorubicin belonging to the anthracycline class of natural products. Due to its extremely high potency and only partially understood mechanism of action, it was deemed an interesting starting point for the development of a new suite of linker drugs for antibody drug conjugates (ADCs). Structure activity relationships were explored on the small molecule which led to six linker drugs being developed for conjugation to antibodies. Herein we describe the synthesis of novel PNU-159682 derivatives and the subsequent linker drugs as well as the corresponding biological evaluations of the small molecules and ADCs.

One-pot synthesis of acid-degradable polyphosphazene prodrugs for efficient tumor chemotherapy.

In order to improve the therapeutic efficacy and reduce the side effects of anticancer drugs, stimuli-responsive and biodegradable drug-delivery systems have attracted significant attention in the past three decades. Herein, we report acid-responsive and degradable polyphosphazene nano-prodrugs synthesized via a one-pot cross-linking reaction of 4-hydroxybenzhydrazide-modified doxorubicin (BMD) with hexachlorocyclotriphosphazene (HCCP). The phenol groups in the as-synthesized BMD exhibited a high reactivity towards HCCP and in the presence of a basic catalyst the determined drug loading ratio of the nanoparticles, denoted as HCCP-BMD, was up to 85.64%. Interestingly, the hydrazone bonds in BMD and the skeleton of polyphosphazene tended to break down in acidic environments, and the antitumor active drug DOX was found to be released in an acidic tumor microenvironment (pH ∼ 6.8 for extracellular, and pH ∼ 5.0 for endosomes and lysosomes). The resulting HCCP-BMD prodrug exhibited high cytotoxicity to HeLa cells and could effectively suppress tumor growth, with negligible damage to normal tissues. We therefore believe that this acid- degradable polyphosphazene prodrug may offer great potential in various biomedical fields.

Lipid/Hyaluronic Acid-Coated Doxorubicin-Fe3O4 as a Dual-Targeting Nanoparticle for Enhanced Cancer Therapy.

Development of a delivery system to lower systemic toxicity and enhance doxorubicin (DOX) antitumor efficacy against multi-drug resistant (MDR) tumors is of great clinical significance. Here, lipid/hyaluronic acid (HA)-coated DOX-Fe3O4 was characterized to determine its optimal safety and efficacy on a tumor. DOX was first conjugated onto the Fe3O4 NPs surface, which was subsequently coated with phosphatidylcholine (PC) lipids, which consisted of a tumor cell-targeting HA ligand, to generate a dual-targeting nanoparticle (NP). DOX-Fe3O4 synthesis was validated by the Fourier-transform infrared (FT-IR) analysis results. Core-shell PC/HA@DOX-Fe3O4 formation, which had an average particle size of 48.2 nm, was observed based on the transmission electron microscopy (TEM) and dynamic laser light scattering (DLS) results. The saturation magnetization value of PC/HA@DOX-Fe3O4 was discovered to be 28 emu/g using vibrating-sample magnetometry. Furthermore, the designed PC/HA@DOX-Fe3O4 achieved greater MCF-7/ADR cellular uptake and cytotoxicity as compared with DOX. In addition, PC/HA@DOX-Fe3O4 exhibited significant DOX tumor-targeting capabilities and enhanced tumor growth inhibition activity in the xenograft MCF-7/ADR tumor-bearing nude mice following magnetic attraction and ligand-mediated targeting, with less cardiotoxicity. Therefore, PC/HA@DOX-Fe3O4 is a potential candidate for MDR tumor chemotherapy. Graphical abstract.

Scalable solvent-free production of liposomes.

OBJECTIVES: A major challenge faced with the manufacture of liposomes is the high volumes of organic solvents used during manufacturing. Therefore, we have implemented an organic solvent-free production method for drug-loaded liposomes and demonstrated its applicability with both aqueous core-loaded and bilayer-loaded drugs. METHODS: Liposomes were produced by high shear mixing dry powder lipids with an aqueous buffer, followed by down-sizing using a Microfluidizer processor. Liposomes were purified via tangential flow filtration and characterised in terms of size, polydispersity index, zeta potential and drug loading. KEY FINDINGS: Doxorubicin-loaded PEGylated liposomes can be manufactured using this solvent-free method with particle sizes of 100-110 nm, low polydispersity index (PDI) (<0.2) and high drug loading (97-98%). If required, liposomes can be further down-sized via microfluidic processing without impacting drug loading. Similar results were achieved with non-PEGylated liposomes. With bilayer-loaded amphotericin B liposomes, again liposomes can be prepared within a clinically appropriate size range (100-110 nm in size, low PDI) with high drug loading (98-100%). CONCLUSIONS: We apply a simple and scalable solvent-free method for the production of both aqueous core or bilayer drug-loaded liposomes.

Charge reversible hyaluronic acid-modified dendrimer-based nanoparticles for siMDR-1 and doxorubicin co-delivery.

Dendrimer-based nanoparticles have shown promising applications in delivery of small interference RNA (siRNA) to downregulate proteins that contribute to multidrug resistance (MDR). Various types of modification can further enhance the anti-tumor efficacy of dendrimer-based nanoparticles. In this study, generation 4 polyamodoamine (PAMAM) was conjugated with PEG2k-DOPE. The PAMAM-PEG2k-DOPE co-polymer, together with mPEG2k-DOPE, was formulated into mixed dendrimer micelles (MDMs) that can complex siRNA through the cationic PAMAM moieties and encapsulate hydrophobic drug in the micellar lipid cores. DOPE-conjugated hyaluronic acid (HA) was coated on the surface of MDMs to shield the exposed positive charge on PAMAM and to increase the cellular association with CD44+ cancer cells. The HA-modified MDMs could form stable complexes with siRNA, prevent RNase-mediated siRNA degradation and maintain its integrity. Cellular association and cytotoxicity of HA-modified MDMs were investigated in A2780 ADR, MDA-MB-231 and HCT 116 cell lines. The HA-modified MDMs alleviated the toxicity from cationic charge, increase the cancer cell specificity and enhance the cancer cell killing effect in CD44+ cell line.

Formulation of Stattic as STAT3 inhibitor in nanostructured lipid carriers (NLCs) enhances efficacy of doxorubicin in melanoma cancer cells.

Nowadays, nanoparticle-based combination therapy has been emerging as huge innovation in cancer treatment. Here, we studied the effect of Stattic (STAT3 inhibitor) loaded in nanostructured lipid carriers (NLCs) on enhancing the efficacy, cytotoxicity, and induction of apoptosis of doxorubicin in B16F10 mouse melanoma cancer cell. The evaluation of Stattic-loaded NLCs has been done in terms of zeta potential, particle size, scanning electron microscope (SEM), and cellular uptake. MTT assay was applied to evaluate the cell proliferation. Apoptotic cell death and identification of early and late apoptosis were assessed by DAPI staining and Annexin V/PI staining, respectively. Real-time RT-PCR was applied to measure the effects of doxorubicin and/or Stattic on key apoptotic genes such as Bad, Survivin, HIF1, and STAT3. The Stattic formulated into NLCs shown mean particle size of 56 ± 7 nm which was confirmed by SEM. The IC50 values for Stattic and doxorubicin were 2.95 ± 0.52 µM and 1.21 ± 0.36 µM, respectively. Stattic-loaded NLCs diminished percent of cell proliferation from 68 ± 6.8 to 54 ± 3.7% (p < 0.05). Combinational treatment of the cells with Stattic-loaded nanoparticles and doxorubicin give rise to a significant increase in the percentage of apoptosis (p < 0.05). The study of gene expression profile has shown a remarkable decrease in anti-apoptotic gene, Survivin, along with smooth decline in HIF1 as angiogenesis intermediator and increase in Bad mRNA levels. Our results recommend that NLCs as novel technology have potent strategy to augment efficacy of current chemotherapeutic agent in melanoma cancer cells.

Prodrug-Based Nanoreactors with Tumor-Specific In Situ Activation for Multisynergistic Cancer Therapy.

Efficient drug delivery into tumor cells while bypassing many biological barriers is still a challenge for cancer therapy. By taking advantage of the palladium (Pd)-mediated in situ activation of a prodrug and the glucose oxidase (GOD)-based ß-d-glucose oxidation reaction, we developed a multisynergistic cancer therapeutic platform that combined doxorubicin (DOX)-induced chemotherapy with GOD-mediated cancer-orchestrated oxidation therapy and cancer starvation therapy. In the present work, we first synthesized DOX prodrugs (pDOXs) and temporarily assembled them with ß-cyclodextrins to reduce their toxic side effects. Then, a nanoreactor was constructed by synthesizing Pd0 nanoparticles in situ within the pores of mesoporous silica nanoparticles for the conversion of pDOX into the active anticancer drug. Furthermore, GOD was introduced to decrease the pH of the tumor microenvironment and induce cancer-orchestrated oxidation/starvation therapy by catalyzing ß-d-glucose oxidation to form hydrogen peroxide (H2O2) and gluconic acid. Our study provides a new strategy that employs a cascade chemical reaction to achieve combined orchestrated oxidation/starvation/chemotherapy for the synergistic killing of cancer cells and the suppression of tumor growth.