Nanoparticle delivery and combination therapy of gambogic acid and all-trans retinoic acid

Natural gambogic acid-tuned self-assembly of nanodrugs towards synergistic chemophototherapy against breast cancer

Gambogic acid (GA) as a naturally derived chemotherapeutic agent is of increasing interest for antitumor therapy. However, current research mainly focuses on improving the pharmacological properties to overcome the shortcomings in clinical applications or as a synergistic anticancer agent in combination with chemotherapy and chemophototherapy. Yet, the material properties of GA (e.g., self-assembly) are often neglected. Herein, we validated the self-assembly function of GA and its huge potential as a single-component active carrier for synergistic delivery using pyropheophorbide-a (PPa) as a drug model. The results showed that self-assembled GA drives the formation of nano-GA/PPa mainly through noncovalent interactions such as π-π stacking, hydrophobic interactions, and hydrogen bonding. Additionally, although no significant differences in cytotoxicity were found between the individual in vitro chemotherapy and combined chemophototherapy, the as-prepared nano-GA/PPa exhibits remarkably improved water solubility and multiple favorable therapeutic features, leading to a prominent in vivo photochemotherapy efficiency of 89.3% inhibition rate with reduced hepatotoxicity of GA. This work highlights the potential of self-assembled GA as a drug delivery carrier for synergistic biomedical applications.

Regulating Tumor-Associated Macrophage Polarization by Cyclodextrin-Modified PLGA Nanoparticles Loaded with R848 for Treating Colon Cancer

Purpose

This study aimed to develop a novel and feasible modification strategy to improve the solubility and antitumor activity of resiquimod (R848) by utilizing the supramolecular effect of 2-hydroxypropyl-beta-cyclodextrin (2-HP-β-CD).

Methods

R848-loaded PLGA nanoparticles modified with 2-HP-β-CD (CD@R848@NPs) were synthesized using an enhanced emulsification solvent-evaporation technique. The nanoparticles were then characterized in vitro by several methods, such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, particle size analysis, and zeta potential analysis. Then, the nanoparticles were loaded with IR-780 dye and imaged using an in vivo imaging device to evaluate their biodistribution. Additionally, the antitumor efficacy and underlying mechanism of CD@R848@NPs in combination with an anti-TNFR2 antibody were investigated using an MC-38 colon adenocarcinoma model in vivo.

Results

The average size of the CD@R848@NPs was 376 ± 30 nm, and the surface charge was 21 ± 1 mV. Through this design, the targeting ability of 2-HP-β-CD can be leveraged and R848 is delivered to tumor-supporting M2-like macrophages in an efficient and specific manner. Moreover, we used an anti-TNFR2 antibody to reduce the proportion of Tregs. Compared with plain PLGA nanoparticles or R848, CD@R848@NPs increased penetration in tumor tissues, dramatically reprogrammed M1-like macrophages, removed tumors and prolonged patient survival.

Conclusion

The new nanocapsule system is a promising strategy for targeting tumor, reprogramming tumor -associated macrophages, and enhancement immunotherapy.

Caged Polyprenylated Xanthones in Garcinia hanburyi and the Biological Activities of Them

The previous phytochemical analyses of Garcinia hanburyi revealed that the main structural characteristic associated with its biological activity is the caged polyprenylated xanthones with a unique 4-oxatricyclo [4.3.1.03,7] dec-2-one scaffold, which contains a highly substituted tetrahydrofuran ring with three quaternary carbons. Based on the progress in research of the chemical constituents, pharmacological effects and modification methods of the caged polyprenylated xanthones, this paper presents a preliminary predictive analysis of their drug-like properties based on the absorption, distribution, metabolism, excretion and toxicity (ADME/T) properties. It was found out that these compounds have very similar pharmacokinetic properties because they possess the same caged xanthone structure, the 9,10-double bond in a,b-unsaturated ketones are critical for the antitumor activity. The author believes that there is an urgent need to seek new breakthroughs in the study of these caged polyprenylated xanthones. Thus, the research on the route of administration, therapeutic effect, structural modification and development of such active ingredients is of great interest. It is hoped that this paper will provide ideas for researchers to develop and utilize the active ingredients derived from natural products.

Optimization of amino acid-based poly(ester urea urethane) nanoparticles for the systemic delivery of gambogic acid for treating triple negative breast cancer

Amino acid-based poly(ester urea urethane) (AA-PEUU) is developed from amino acid-based ester urea building blocks interconnected with urethane blocks functionalized with poly(ethylene glycol) (PEG). Each functional block consists of structural design features that could impact the properties and performances of AA-PEUU as a nanocarrier for the systemic delivery of gambogic acid (GA). The multifunctional AA-PEUU structure provides broad tunability to enable the optimization of nanocarriers. The study investigates the structure-property relationship by fine-tuning the structure of AA-PEUU, including the amino acid type, hydrocarbons, the ratio of functional building blocks, and PEGylation, to identify the nanoparticle candidate with optimized delivery performances. Compared to free GA, the optimized PEUU nanocarrier improves the intratumoral distribution of GA by more than 9-fold, which significantly enhances the bioavailability and persistence of GA after intravenous administration. In an MDA-MB-231 xenograft mouse model, GA delivered by the optimized AA-PEUU nanocarrier exhibits significant tumor inhibition, apoptosis induction, and the anti-angiogenesis effect. The study demonstrates the potency of engineering AA-PEUU nanocarriers with tailor-designed structures and versatile tunability for the systemic delivery of therapeutics in the treatment of triple negative breast tumor.

MMP2-responsive dual-targeting drug delivery system for valence-controlled arsenic trioxide prodrug delivery against hepatic carcinoma

Arsenic trioxide (ATO) is the active ingredient in traditional Chinese medicine, i.e., Arsenic, which has shown excellent therapeutic effects on hepatocellular carcinoma. However, due to its poor tumor distribution and high toxicity, the mass adoption of ATO in clinical applications has been severely impeded. In this study, matrix metalloproteinase 2 (MMP2)-responsive cleaved cell-penetrating peptide (PF) and folate (FA) co-modified liposome coated calcium arsenate nanoparticles (FA/PF-LP-CaAs) were fabricated based on these two considerations: (1) The tumor microenvironment characterized by overexpressed MMP2 in extracellular matrix and folate receptor on the cell membrane can enhance drug accumulation and accelerate endocytosis; (2) leveraging different toxicity of arsenic in different valence states, i.e., AsV can be reduced to more toxic AsIII by glutathione in tumor cells. Furthermore, FA/PF-LP-CaAs could be responsively degraded by the mild acidic tumor environment, and the degraded product could escape from lysosomes after endocytosis. More importantly, in light of the in vivo biodistribution and pharmacodynamic studies, the vehicle was able to accumulate in the tumor efficiently. Also, it was able to exhibit excellent anti-tumor efficacy with minimized side effects when compared to single-modified counterparts. Thus, the novel strategy based on the tumor microenvironment proposed in this work can enhance the tumor-targeting efficiency and intratumor toxicity.

Hyaluronan-based Multifunctional Nano-carriers for Combination Cancer Therapy

Hyaluronan (HA) is a natural linear polysaccharide that has excellent hydrophilicity, biocompatibility, biodegradability, and low immunogenicity, making it one of the most attractive biopolymers used for biomedical researches and applications. Due to the multiple functional sites on HA and its intrinsic affinity for CD44, a receptor highly expressed on various cancer cells, HA has been widely engineered to construct different drug-loading nanoparticles (NPs) for CD44-targeted anti-tumor therapy. When a cocktail of drugs is co-loaded in HA NP, a multifunctional nano-carriers could be obtained, which features as a highly effective and self-targeting strategy to combat cancers with CD44 overexpression. The HA-based multidrug nano-carriers can be a combination of different drugs, various therapeutic modalities, or the integration of therapy and diagnostics (theranostics). Up to now, there are many types of HA-based multidrug nano-carriers constructed by different formulation strategies, including drug co-conjugates, micelles, nano-gels and hybrid NP of HA and so on. This multidrug nano-carrier takes the full advantages of HA as an NP matrix, drug carriers and targeting ligand, representing a simplified and biocompatible platform to realize the targeted and synergistic combination therapy against the cancers. In this review, recent progress of HA-based multidrug nano-carriers for combination cancer therapy is summarized and the potential challenges for translational applications have been discussed.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Gambogic Acid as a Candidate for Cancer Therapy: A Review

Gambogic acid (GA), a kind of dry resin secreted by the Garcinia hanburyi tree, is a natural active ingredient with various biological activities, such as anti-cancer, anti-inflammatory, antioxidant, anti-bacterial effects, etc. An increasing amount of evidence indicates that GA has obvious anti-cancer effects via various molecular mechanisms, including the induction of apoptosis, autophagy, cell cycle arrest and the inhibition of invasion, metastasis, angiogenesis. In order to improve the efficacy in cancer treatment, nanometer drug delivery systems have been employed to load GA and form micelles, nanoparticles, nanofibers, and so on. In this review, we aim to offer a summary of chemical structure and properties, anti-cancer activities, drug delivery systems and combination therapy of GA, which might provide a reference to promote the development and clinical application of GA.

Current Trends in ATRA Delivery for Cancer Therapy

All-Trans Retinoic Acid (ATRA) is the most active metabolite of vitamin A. It is critically involved in the regulation of multiple processes, such as cell differentiation and apoptosis, by activating specific genomic pathways or by influencing key signaling proteins. Furthermore, mounting evidence highlights the anti-tumor activity of this compound. Notably, oral administration of ATRA is the first choice treatment in Acute Promyelocytic Leukemia (APL) in adults and NeuroBlastoma (NB) in children. Regrettably, the promising results obtained for these diseases have not been translated yet into the clinics for solid tumors. This is mainly due to ATRA-resistance developed by cancer cells and to ineffective delivery and targeting. This up-to-date review deals with recent studies on different ATRA-loaded Drug Delivery Systems (DDSs) development and application on several tumor models. Moreover, patents, pre-clinical, and clinical studies are also reviewed. To sum up, the main aim of this in-depth review is to provide a detailed overview of the several attempts which have been made in the recent years to ameliorate ATRA delivery and targeting in cancer.

Recognition Sites for Cancer-targeting Drug Delivery Systems

BACKGROUND

Target-homing drug delivery systems are now gaining significant attention for use as novel therapeutic approaches in antitumor targeting for cancer therapy. Numerous targeted drug delivery systems have been designed to improve the targeting effects because these systems can display a range of favorable properties, thus, providing suitable characteristics for clinical applicability of anticancer drugs, such as increasing the solubility, and improving the drug distribution at target sites. The majority of these targeting systems are designed with respect to differences between cancerous and normal tissues, for instance, the low pH of tumor tissues or overexpressed receptors on tumor cell membranes. Due to the growing number of targeting possibilities, it is important to know the tumor-specific recognition strategies for designing novel, targeted, drug delivery systems. Herein, we identify and summarize literature pertaining to various recognition sites for optimizing the design of targeted drug delivery systems to augment current chemotherapeutic approaches.

OBJECTIVE

This review focuses on the identification of the recognition sites for developing targeted drug delivery systems for use in cancer therapeutics.

METHODS

We have reviewed and compiled cancer-specific recognition sites and their abnormal characteristics within tumor tissues (low pH, high glutathione, targetable receptors, etc.), tumor cells (receptor overexpression or tumor cell membrane changes) and tumor cell organelles (nuclear and endoplasmic reticular dysregulation) utilizing existing scientific literature. Moreover, we have highlighted the design of some targeted drug delivery systems that can be used as homing tools for these recognition sites.

RESULTS AND CONCLUSION

Targeted drug delivery systems are a promising therapeutic approach for tumor chemotherapy. Additional research focused on finding novel recognition sites, and subsequent development of targeting moieties for use with drug delivery systems will aid in the evaluation and clinical application of new and improved chemotherapeutics.

Antitumor Activity of Thermosensitive Hydrogels Packaging Gambogic Acid Nanoparticles and Tumor-Penetrating Peptide iRGD Against Gastric Cancer

Introduction

Gambogic acid (GA) is proved to have anti-tumor effects on gastric cancer. Due to poor solubility, non-specific biological distribution, toxicity to normal tissues and short half-life, it is hard to be applied into the clinic. To overcome these issues, we developed a thermosensitive and injectable hydrogel composed of hydroxypropyl cellulose, silk fibroin and glycerol, with short gelling time, good compatibility and sustained release, and demonstrated that the hydrogel packaged with gambogic acid nanoparticles (GA-NPs) and tumor-penetrating peptide iRGD could improve the anti-tumor activity.

Methods

The Gelling time and micropore size of the hydrogels were regulated through different concentrations of glycerol. Controlled release characteristics of the hydrogels were evaluated with a real-time near-infrared fluorescence imaging system. Location of nanoparticles from different carriers was traced by confocal laser scanning microscopy. The in vivo antitumor activity of the hydrogels packaging GA-NPs and iRGD was evaluated by investigating tumor volume and tumor size.

Results

The thermo-sensitive properties of hydrogels were characterized by 3-4 min, 37°C, when glycerol concentration was 20%. The hydrogels physically packaged with GA-NPs and iRGD showed higher fluorescence intensity than other groups. The in vivo study indicated that the co-administration of GA-NPs and iRGD by hydrogels had higher antitumor activity than the GA-loaded hydrogels and free GA combining with iRGD. Free GA group showed few antitumor effects. Compared with the control group, the body weight in other groups had no obvious change, and the count of leukocytes and hemoglobin was slightly decreased.

Discussion

The hydrogel constructed iRGD and GA-NPs exerted an effective anti-tumor effect possibly due to retention effect, local administration and continuous sustained release of iRGD promoting the penetration of nanoparticles into a deep part of tumors. The delivery system showed little systemic toxicity and would provide a promising strategy to improve anti-gastric cancer efficacy.

Improved druggability of gambogic acid using core–shell nanoparticles

A core-shell hybrid nanoparticle has been developed to improve the druggability of Gambogic acid (GA), a natural antitumor drug candidate.

Implication of linker length on cell cytotoxicity, pharmacokinetic and toxicity profile of gemcitabine-docetaxel combinatorial dual drug conjugate

The present study investigates effect of linkers [zero length (without linker), short length linker (glycine and lysine) and long length linker (PEG1000, PEG2000 and PEG3500)] on pharmacokinetics and toxicity of docetaxel (DTX) and gemcitabine (GEM) bio-conjugates. Conjugates were synthesized via carbodiimide chemistry and characterized by ¹H NMR and FTIR. Conjugation of DTX and GEM via linkers showed diverse physiochemical and plasma stability profile. Cellular uptake mechanism in MCF-7 and MDA-MB-231 cell lines revealed clathrin mediated internalization of bio-conjugates developed by using long length linkers, leading to higher cytotoxicity compared with free drug congeners. DTX-PEG3500-GEM and DTX-PEG2000-GEM demonstrated 4.21 and 3.81-fold higher AUC_(0-∞) of GEM in comparison with GEM alone. DTX-PEG2000-GEM and DTX-PEG3500-GEM exhibited reduced hepato-, nephro- and haemolytic toxicity as evident via histopathology, biochemical markers and SEM analysis of RBCs. Conclusively, PEG2000 and PEG3500 significantly improved pharmacokinetics without any sign of toxicity and hence can be explored further for the development of dual-drug conjugates for better therapeutic efficacy.

Pluronic F68-Linoleic Acid Nano-spheres Mediated Delivery of Gambogic Acid for Cancer Therapy

Gambogic acid (GA), a natural compound from gamboge resin, has been introduced as a promising antitumor drug contributing to its broad spectrum of antitumor activity. However, the poor aqueous solubility and short half-life hinder its clinical application. Pluronic F68 (F68) is a well-known amphiphilic block copolymer consisting of hydrophobic propylene oxide units and hydrophilic ethylene oxide. Although F68 has an amphiphilic structure, its short propylene oxide segment limits its dilution stability and drug-loading capacity. To overcome this limitation, we modified F68 by conjugating linoleic acid, a hydrophobic fatty acid, to increase the hydrophilic-hydrophobic interaction and thus improve the stability of F68 nano-spheres. This F68-linoleic acid (F68-LA) conjugate was synthesized and was used to load GA to improve its anticancer effects. GA-loaded F68-LA nano-spheres were stable for 6 days, with a mean diameter of 159.3 nm and zeta potential of -23.2 mV. The entrapment efficiency of GA in F68-LA nano-spheres was as high as 92.0%. Furthermore, F68-LA/GA nano-spheres exhibited an enhanced cytotoxic activity and proapoptotic effect against human ovarian cancer A2780 cells, compared with free GA. Our results showed that the F68-LA/GA nano-spheres might be a promising cancer-targeted drug delivery system in ovarian cancer therapy.

Folate-decorated arginine-based poly(ester urea urethane) nanoparticles as carriers for gambogic acid and effect on cancer cells

Gambogic acid (GA) exhibits a broad spectrum of anticancer activity and low chemotoxicity to normal tissues. However, poor aqueous solubility and sensitivity to hydrolysis make its pharmaceutical applications a challenge. Linear and branched Arg-based poly(ester urea urethane)s (Arg-PEUUs), folate (FA)-conjugated Arg PEUUs (FA-Arg-PEUUs), and their self-assembled nanoparticles (NPs) were designed, synthesized, and studied as the potential GA carriers for cancer treatment. The average diameters of linear or branched Arg-PEUU/FA-Arg-PEUU NPs were 98-267 nm. FA-Arg-PEUU NPs adhered onto and were internalized into HeLa and A549 cells, and showed no cytotoxicity. The GA loading efficiency in the NP carriers ranged from 40 to 98%, depending on the feed weight ratio of GA to Arg-PEUU and the Arg-PEUU polymer structure (i.e., linear vs. branched). The GA at 2 µg/mL concentration delivered by the FA-Arg-PEUU NP carriers had higher cytotoxicity and induced a higher apoptosis percentage against folate receptor (FR)-overexpressed HeLa or HCT116 than Arg-PEUU NPs. When compared to the free GA treatment, the GA loaded in the FA-Arg-PEUU NP carriers also led to significant loss of the mitochondrial membrane potential in a higher percentage of the cancer cell population and more DNA fragmentation. The GA loaded in FA-Arg-PEUU NP carriers at as low as 0.6 µg/mL GA concentration led to lower MMP-2 and MMP-9 activity of cancer cells compared to free GA, suggesting that GA-loaded Arg-PEUU NPs may have greater potential to reduce cancer cell invasion and metastasis than free GA. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 475-490, 2017.

Targeting Cancer using Polymeric Nanoparticle mediated Combination Chemotherapy

Cancer forms exhibiting poor prognosis have been extensively researched for therapeutic solutions. One of the conventional modes of treatment, chemotherapy shows inadequacy in its methodology due to imminent side-effects and acquired drug-resistance by cancer cells. However, advancements in nanotechnology have opened new frontiers to significantly alleviate collateral damage caused by current treatments via innovative delivery techniques, eliminating pitfalls encountered in conventional treatments. Properties like reduced drug-clearance and increased dose efficacy by the enhanced permeability and retention effect deem nanoparticles suitable for this application. Optimization of size, surface charge and surface modifications have provided nanoparticles with stealth properties capable of evading immune responses, thus deeming them as excellent carriers of chemotherapeutic agents. Biocompatible and biodegradable forms of polymers enhance the bioavailability of chemotherapeutic agents, and permit a sustained and time-dependent release of drugs which is a characteristic of their composition, thereby providing a controlled therapeutic approach. Studies conducted in vitro and animal models have also demonstrated a synergism in cytotoxicity given the mechanism of action of anticancer drugs when administered in combination providing promising results. Combination therapy has also shown implications in overcoming multiple-drug resistance, which can however be subdued by the adaptable nature of tumor microenvironment. Surface modifications with targeting moieties can therefore feasibly increase nanoparticle uptake by specific receptor-ligand interactions, increasing dose efficacy which can seemingly overcome drug-resistance. This article reviews recent trends and investigations in employing polymeric nanoparticles for effectively delivering combination chemotherapy, and modifications in delivery parameters enhancing dose efficacy, thus validating the potential in this approach for anticancer treatment.

Nanomedicine-based combination of gambogic acid and retinoic acid chlorochalcone for enhanced anticancer efficacy in osteosarcoma

In this study, gambogic acid (GA) and retinoic acid chlorochalcone (RACC) co-loaded glycol chitosan nanoparticle was successfully developed and studied for its therapeutic efficacy against osteosarcoma cancer cells. The GA/RACC loaded glycol chitosan nanoparticles (RGNP) was nanosized and exhibited a controlled release of drug in either pH 7.4 and pH 5.0. Owing to the strong positive charge on the RGNP surface, efficiency cellular uptake was observed in cancer cells. Moreover, a synergistic combination of GA and RACC were effectively suppressed the tumor growth progression. The half maximal inhibitory concentration (IC50) values in MG63 cells were 0.89μg/ml and 0.35μg/ml for GA and RGNP after 24h. The results clearly suggest the synergist effect of GA and RACC in effectively inhibiting the cancer cell proliferation. The RGNP as expected induced a remarkably higher apoptosis of cancer cells with ∼28%. Overall, combination of GA and RACC encapsulated in a nanocarrier could be an effective strategy to treat osteosarcoma. Future studies will focus on the in vivo evaluation of GA/RACC-loaded polymeric nanoparticles.

Tumor neovasculature-targeted cationic PEGylated liposomes of gambogic acid for the treatment of triple-negative breast cancer

Gambogic acid (GA) is a naturally derived potent anticancer agent with extremely poor aqueous solubility. In the present study, positively charged PEGylated liposomal formulation of GA (GAL) was developed for parenteral delivery for the treatment of triple-negative breast cancer (TNBC). The GAL was formulated with a particle size of 107.3 ± 10.6 nm with +32 mV zeta potential. GAL showed very minimal release of GA over 24 h period confirming the non-leakiness and stability of liposomes. In vitro cytotoxicity assays showed similar cell killing with GA and GAL against MDA-MB-231 cells but significantly higher inhibition of HUVEC growth was observed with GAL. Furthermore, GAL significantly (p < 0.05) inhibited the MDA-MB-231 orthotopic xenograft tumor growth with >50% reduction of tumor volume and reduction in tumor weight by 1.7-fold and 2.2-fold when compared to GA and controls, respectively. Results of western blot analysis indicated that GAL significantly suppressed the expression of apoptotic markers, bcl2, cyclinD1, survivin and microvessel density marker-CD31 and increased the expression of p53 and Bax compared to GA and control. Collectively, these data provide further support for the potential applications of cationic GAL in its intravenous delivery and its significant role in inhibiting angiogenesis against TNBC.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Retinal-conjugated pH-sensitive micelles induce tumor senescence for boosting breast cancer chemotherapy

Evoking tumor cellular senescence, an irreversible status of cell growth quiescence, has been recently proposed as a potential strategy to improve the efficacy of cancer treatment. In the current study, all-trans retinal, the precursor of all-trans retinoic acid, was conjugated to dextran via hydrazone bond to generate amphiphilic dextran-retinal (DR) conjugates, which self-assembled into pH-sensitive DR micelles. Our results showed that DR micelles moderately inhibited MCF-7 breast cancer cell growth through inducing p21-associated cellular senescence, which relied on retinoic acid receptors (RARs) and was accompanied by significant G0/G1 cell cycle arrest. Moreover, DR micelles were capable of encapsulating doxorubicin (DOX) to generate DOX-loaded DD micelles, facilitating the uptake and release of DOX in cancer cells. Compared with free DOX, DD micelles more effectively suppressed tumor growth and prolonged survival time of mouse xenograft model through inducing tumor apoptosis and cellular senescence. However, blocking cellular senescence diminished DD-caused apoptosis in MCF-7 cells by 40-50%. Therefore, pH-sensitive DR micelles not only served as a potent platform for DOX delivery, but also enhanced the anti-tumor effect of DOX by inducing tumor cellular senescence. These data reveal a great potential of evoking tumor senescence with retinal-conjugated micelles for boosting breast cancer chemotherapy.

Enhanced antitumor effects by docetaxel/LL37-loaded thermosensitive hydrogel nanoparticles in peritoneal carcinomatosis of colorectal cancer

Intraperitoneal chemotherapy was explored in clinical trials as a promising strategy to improve the therapeutic effects of chemotherapy. In this work, we developed a biodegradable and injectable drug-delivery system by coencapsulation of docetaxel (Doc) and LL37 peptide polymeric nanoparticles (Doc+LL37 NPs) in a thermosensitive hydrogel system for colorectal peritoneal carcinoma therapy. Firstly, polylactic acid (PLA)-Pluronic L35-PLA (PLA-L35-PLA) was explored to prepare the biodegradable Doc+LL37 NPs using a water-in-oil-in-water double-emulsion solvent-evaporation method. Then, biodegradable and injectable thermosensitive PLA-L64-PLA hydrogel with lower sol–gel transition temperature at around body temperature was also prepared. Transmission electron microscopy revealed that the Doc+LL37 NPs formed with the PLA-L35-PLA copolymer were spherical. Fourier-transform infrared spectra certified that Doc and LL37 were encapsulated successfully. X-ray diffraction diagrams indicated that Doc was encapsulated amorphously. Intraperitoneal administration of Doc+LL37 NPs–hydrogel significantly suppressed the growth of HCT116 peritoneal carcinomatosis in vivo and prolonged the survival of tumor-bearing mice. Our results suggested that Doc+LL37 NPs–hydrogel may have potential clinical applications.

Intravenous delivery of camptothecin-loaded PLGA nanoparticles for the treatment of intracranial glioma

Effective treatment of glioblastoma multiforme remains a major clinical challenge, due in part to the difficulty of delivering chemotherapeutics across the blood-brain barrier. Systemically administered drugs are often poorly bioavailable in the brain, and drug efficacy within the central nervous system can be limited by peripheral toxicity. Here, we investigate the ability of systemically administered poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) to deliver hydrophobic payloads to intracranial glioma. Hydrophobic payload encapsulated within PLGA NPs accumulated at ∼10× higher levels in tumor compared to healthy brain. Tolerability of the chemotherapeutic camptothecin (CPT) was improved by encapsulation, enabling safe administration of up to 20mg/kg drug when encapsulated within NPs. Immunohistochemistry staining for γ-H2AFX, a marker for double-strand breaks, demonstrated higher levels of drug activity in tumors treated with CPT-loaded NPs compared to free drug. CPT-loaded NPs were effective in slowing the growth of intracranial GL261 tumors in immune competent C57 albino mice, providing a significant survival benefit compared to mice receiving saline, free CPT or low dose CPT NPs (median survival of 36.5 days compared to 28, 32, 33.5 days respectively). In sum, these data demonstrate the feasibility of treating intracranial glioma with systemically administered nanoparticles loaded with the otherwise ineffective chemotherapeutic CPT.