Synergistic nanoparticulate drug combination overcomes multidrug resistance, increases efficacy, and reduces cardiotoxicity in a nonimmunocompromised breast tumor model

An update on strategies for optimizing polymer-lipid hybrid nanoparticle-mediated drug delivery: exploiting transformability and bioactivity of PLN and harnessing intracellular lipid transport mechanism

INTRODUCTION

Polymer-lipid hybrid nanoparticle (PLN) is an emerging nanoplatform with distinct properties and functionalities from other nanocarrier systems. PLN can be optimized to overcome various levels of drug delivery barriers to achieve desired therapeutic outcomes via rational selection of polymer and lipid combinations based on a thorough understanding of their properties and interactions with therapeutic agents and biological systems.

AREAS COVERED

This review provides an overview of PLN including the motive and history of PLN development, types of PLN, preparation methods, attestations of their versatility, and design strategies to circumvent various barriers for increasing drug delivery accuracy and efficiency. It also highlights recent advances in PLN design including: rationale selection of polymer and lipid components to achieve spatiotemporal drug targeting and multi-targeted cascade drug delivery; utilizing the intracellular lipid transport mechanism for active targeting to desired organelles; and harnessing bioreactive lipids and polymers to magnify therapeutic effects.

EXPERT OPINION

A thorough understanding of properties of PLN components and their biofate is important for enhancing disease site targeting, deep tumor tissue penetration, cellular uptake, and intracellular trafficking of PLN. For futuristic PLN development, active lipid transport and dual functions of lipids and polymers as both nanocarrier material and pharmacological agents can be further explored.

Lipid-based nanoparticle-mediated combination therapy for breast cancer management: a comprehensive review

Breast cancer due to the unpredictable and complex etiopathology combined with the non-availability of any effective drug treatment has become the major root of concern for oncologists globally. The number of women affected by the said disease state is increasing at an alarming rate attributed to environmental and lifestyle changes indicating at the exploration of a novel treatment strategy that can eradicate this aggressive disease. So far, it is treated by promising nanomedicine monotherapy; however, according to the numerous studies conducted, the inadequacy of these nano monotherapies in terms of elevated toxicity and resistance has been reported. This review, therefore, puts forth a new multimodal strategic approach to lipid-based nanoparticle-mediated combination drug delivery in breast cancer, emphasizing the recent advancements. A basic overview about the combination therapy and its index is firstly given. Then, the various nano-based combinations of chemotherapeutics involving the combination delivery of synthetic and herbal agents are discussed along with their examples. Further, the recent exploration of chemotherapeutics co-delivery with small interfering RNA (siRNA) agents has also been explained herein. Finally, a section providing a brief description of the delivery of chemotherapeutic agents with monoclonal antibodies (mAbs) has been presented. From this review, we aim to provide the researchers with deep insight into the novel and much more effective combinational lipid-based nanoparticle-mediated nanomedicines tailored specifically for breast cancer treatment resulting in synergism, enhanced antitumor efficacy, and low toxic effects, subsequently overcoming the hurdles associated with conventional chemotherapy.

Microfluidics-based PLGA nanoparticles of ratiometric multidrug: From encapsulation and release rates to cytotoxicity in human lens epithelial cells

Multidrug nanomedicine is an effective therapeutic approach for the treatment of chronic diseases and cancers. However, co-encapsulation and release of drug combination at a fixed ratio by nanoparticles, particularly for long acting ocular formulations, remains challenging. Herein, poly (lactic-co-glycolic acid) nanoparticles ratiometrically co-encapsulating hydrophilic dual drugs, mitomycin C and doxorubicin, was obtained (D/M PLGANPs) by combining microfluidics and the Design of Experiments approaches. The formulation variable of lactide-to-glycolide ratios (L/G 50:50, 75:15 and 85:15) was used to achieve fast, medium and slow drug release rates of D/M PLGANPs. The dissolution of D/M PLGANPs in simulated intraocular fluid exhibited sustained release of dual drugs at the fixed ratio over 7 days, and analysis using the Korsmeyer-Peppas model showed mechanism of drug release to be governed by diffusion. More importantly, in human lens epithelial cells, the drug release rate was negatively correlated with drug potency. The slower drug release from D/M PLGANPs led to lower efficacy of drug combination against pathogenesis of cellular migration and proliferation, the key pathogenic processes of capsular opacification after cataract surgery. Compared to fast (L/G 50:50) and medium (L/G 75:15) drug release rate of D/M PLGANPs, the slow release formulation (L/G 85:15) exhibited the least cellular uptake of the dual drugs and the ratio of drug combination was not maintained intracellularly. The present study implicates the potential of using microfluidics for synthesizing polymeric nanoparticles of ratiometric drug combination and highlights the drug release rate as the critical determinant of efficacy for the long-acting nanomedicine design.

Clinical Translation of Long-Acting Drug Delivery Systems for Posterior Capsule Opacification Prophylaxis

Posterior capsule opacification (PCO) remains the most common cause of vision loss post cataract surgery. The clinical management of PCO formation is limited to either physical impedance of residual lens epithelial cells (LECs) by implantation of specially designed intraocular lenses (IOL) or laser ablation of the opaque posterior capsular tissues; however, these strategies cannot fully eradicate PCO and are associated with other ocular complications. In this review, we critically appraise recent advances in conventional and nanotechnology-based drug delivery approaches to PCO prophylaxis. We focus on long-acting dosage forms, including drug-eluting IOL, injectable hydrogels, nanoparticles and implants, highlighting analysis of their controlled drug-release properties (e.g., release duration, maximum drug release, drug-release half-life). The rational design of drug delivery systems by considering the intraocular environment, issues of initial burst release, drug loading content, delivery of drug combination and long-term ocular safety holds promise for the development of safe and effective pharmacological applications in anti-PCO therapies.

TLR4 Blockade Using Docosahexaenoic Acid Restores Vulnerability of Drug-Tolerant Tumor Cells and Prevents Breast Cancer Metastasis and Postsurgical Relapse

Nonmutational mechanisms were recently discovered leading to reversible drug tolerance. Despite the rapid elimination of a majority of tumor cells, a small subpopulation of "'drug-tolerant"' cells remain viable with lethal drug exposure, which may further lead to resistance or tumor relapse. Several signaling pathways are involved in the local or systemic inflammatory responses contributing to drug-induced phenotypic switch. Here, we report that Toll-like receptor 4 (TLR4)-interacting lipid docosahexaenoic acid (DHA) restores the cytotoxic effect of doxorubicin (DOX) in the lipopolysaccharide-treated breast tumor cell line 4T1, preventing the phenotypic switch to drug-tolerant cells, which significantly reduces primary tumor growth and lung metastasis in both 4T1 orthotopic and experimental metastasis models. Importantly, DHA in combination with DOX delays and inhibits tumor recurrence following surgical removal of the primary tumor. Furthermore, the coencapsulation of DHA and DOX in a nanoemulsion significantly prolongs the survival of mice in the postsurgical 4T1 tumor relapse model with significantly reduced systemic toxicity. The synergistic antitumor, antimetastasis, and antirecurrence effects of DHA + DOX combination are likely mediated by attenuating TLR4 activation, thus sensitizing tumor cells to standard chemotherapy.

Subcellular delivery of lipid nanoparticles to endoplasmic reticulum and mitochondria

Primarily responsible for the biogenesis and metabolism of biomolecules, endoplasmic reticulum (ER) and mitochondria are gradually becoming the targets of therapeutic modulation, whose physiological activities and pathological manifestations determine the functional capacity and even the survival of cells. Drug delivery systems with specific physicochemical properties (passive targeting), or modified by small molecular compounds, polypeptides, and biomembranes demonstrating tropism for ER and mitochondria (active targeting) are able to reduce the nonselective accumulation of drugs, enhancing efficacy while reducing side effects. Lipid nanoparticles feature high biocompatibility, diverse cargo loading, and flexible structure modification, which are frequently used for subcellular organelle-targeted delivery of therapeutics. However, there is still a lack of systematic understanding of lipid nanoparticle-based ER and mitochondria targeting. Herein, we review the pathological significance of drug selectively delivered to the ER and mitochondria. We also summarize the molecular basis and application prospects of lipid nanoparticle-based ER and mitochondria targeting strategies, which may provide guidance for the prevention and treatment of associated diseases and disorders. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Advances in Nanomedicine Design: Multidisciplinary Strategies for Unmet Medical Needs

Globally, a rising burden of complex diseases takes a heavy toll on human lives and poses substantial clinical and economic challenges. This review covers nanomedicine and nanotechnology-enabled advanced drug delivery systems (DDS) designed to address various unmet medical needs. Key nanomedicine and DDSs, currently employed in the clinic to tackle some of these diseases, are discussed focusing on their versatility in diagnostics, anticancer therapy, and diabetes management. First-hand experiences from our own laboratory and the work of others are presented to provide insights into strategies to design and optimize nanomedicine- and nanotechnology-enabled DDS for enhancing therapeutic outcomes. Computational analysis is also briefly reviewed as a technology for rational design of controlled release DDS. Further explorations of DDS have illuminated the interplay of physiological barriers and their impact on DDS. It is demonstrated how such delivery systems can overcome these barriers for enhanced therapeutic efficacy and how new perspectives of next-generation DDS can be applied clinically.

Psoralen-loaded polymeric lipid nanoparticles combined with paclitaxel for the treatment of triple-negative breast cancer

Background: Chemotherapeutic drugs are associated with toxic effects. Metastasis is the leading cause of death in breast cancer patients. Aim: To evaluate the antitumor effect of paclitaxel (PTX) combined with psoralen-loaded polymeric lipid nanoparticles (PSO-PLNs) in triple-negative breast cancer. Methods: After treatment of samples, cell viability, apoptosis, migration, invasion, expression of proteins in the IRAK1/NF-κB/FAK signal pathway, biodistribution and pathological characteristics were detected. Results: Compared with the control group, the PTX + PSO-PLNs group showed increased apoptosis and reduced migration, invasion and expression of phosphorylated IRAK1 and NF-κB, with significant inhibition of tumor growth and lung metastases and no obvious toxicity. Conclusion: Combined administration of PTX and PSO-PLNs exerted a synergistic effect and significantly inhibited the growth and metastasis of triple-negative breast cancer.

Strategies for Preparing Different Types of Lipid Polymer Hybrid Nanoparticles in Targeted Tumor Therapy

At present, cancer is one of the most common diseases in the world, causing a large number of deaths and seriously affecting people's health. The traditional treatment of cancer is mainly surgery, radiotherapy or chemotherapy. Conventional chemotherapy is still an important treatment, but it has some shortcomings, such as poor cell selectivity, serious side effects, drug resistance and so on. Nanoparticle administration can improve drug stability, reduce toxicity, prolong drug release time, prolong system half-life, and bring broad prospects for tumor therapy. Lipid polymer hybrid nanoparticles (LPNs), which combine the advantages of polymer core and phospholipid shell to form a single platform, have become multi-functional drug delivery platforms. This review introduces the basic characteristics, structure and preparation methods of LPNs, and discusses targeting strategies of LPNs in tumor therapy in order to overcome the defects of traditional drug therapy.

Exploring the transformability of polymer-lipid hybrid nanoparticles and nanomaterial-biology interplay to facilitate tumor penetration, cellular uptake and intracellular targeting of anticancer drugs

BACKGROUND

Successful delivery of anticancer drugs to intracellular targets requires different properties of the nanocarrier to overcome multiple transport barriers. However, few nanocarrier systems, to date, possess such properties, despite knowledge about the biological fate of inorganic and polymeric nanocarriers in relation to their fixed size, shape and surface properties. Herein, a polymer-lipid hybrid nanoparticle (PLN) system is described with size and shape transformability and its mechanisms of cellular uptake and intracellular trafficking are studied.

METHODS

Pharmaceutical lipids were screened for use in transformable PLN. Mechanisms of cellular uptake and the role of fatty acid-binding proteins in intracellular trafficking of PLN were investigated in breast cancer cells. Intra-tumoral penetration and retention of doxorubicin (DOX) were evaluated by confocal microscopy.

RESULTS

The lead PLNs showed time-dependent size reduction and shape change from spherical to spiky shape. This transformability of PLNs and lipid trafficking pathways facilitated intracellular transport of DOX-loaded PLN (DOX-PLN) into mitochondria and nuclei. DOX-PLN significantly increased DOX penetration and retention over free DOX or non-transformable liposomal DOX particles at 4 h post-intravenous administration.

CONCLUSION

Transformability of PLN and lipid-biology interplay can be exploited to design new nanocarriers for effective drug delivery to tumor cells and intracellular targets.

Nanoparticle delivery of a pH-sensitive prodrug of doxorubicin and a mitochondrial targeting VES-H8R8 synergistically kill multi-drug resistant breast cancer cells

Multi-drug resistance (MDR) remains a major obstacle in cancer treatment while being heavily dependent on mitochondrial activity and drug efflux. We previously demonstrated that cationic lipids, such as the vitamin E succinate modified octahistidine-octaarginine (VES-H₈R₈) conjugate, target mitochondria, resulting in depolarized mitochondria and inhibited drug efflux in MDR breast cancer cells. We hypothesized that the effective cell uptake, efflux inhibition, and mitochondrial depolarization properties of VES-H₈R₈ would synergistically enhance the toxicity of a pH-sensitive prodrug of doxorubicin (pDox) when co-encapsulated in nanoparticles (NPs). pDox was successfully synthesized and validated for pH-sensitive release from NPs under lysosome-mimicking, acidic conditions. The synergistic effect of VES-H₈R₈ and pDox was confirmed against MDR breast cancer cells in vitro. Importantly, synergism was only observed when VES-H₈R₈ and pDox were co-encapsulated in a single nanoparticulate system. The synergistic mechanism was investigated, confirming superior pDox uptake and retention, Pgp efflux inhibition, mitochondrial depolarization, and enhanced induction of ROS, and apoptosis. This work demonstrates the translational potential of doubly-loaded NPs co-encapsulating pDox with VES-H₈R₈ to synergistically kill MDR breast cancer cells.

Development of Promitil®, a lipidic prodrug of mitomycin c in PEGylated liposomes: From bench to bedside

Several liposome products have been approved for the treatment of cancer. In all of them, the active agents are encapsulated in the liposome water phase passively or by transmembrane ion gradients. An alternative approach in liposomal drug delivery consists of chemically modifying drugs to form lipophilic prodrugs with strong association to the liposomal bilayer. Based on this approach, we synthesized a mitomycin c-derived lipidic prodrug (MLP) which is entrapped in the bilayer of PEGylated liposomes (PL-MLP, Promitil®), and activated by thiolytic cleavage. PL-MLP is stable in plasma with thiolytic activation of MLP occurring exclusively in tissues and is more effective and less toxic than conventional chemotherapy in various tumor models. PL-MLP has completed phase I clinical development where it has shown a favorable safety profile and a 3-fold reduction in toxicity as compared to free mitomycin c. Clinical and pharmacokinetic studies in patients with advanced colo-rectal carcinoma have indicated a significant rate of disease stabilization (39%) in this chemo-refractory population and significant prolongation of median survival in patients attaining stable disease (13.9 months) versus progressive disease patients (6.35 months). The pharmacokinetics of MLP was typically stealth with long T½ (~1 day), slow clearance and small volume of distribution. Interestingly, a longer T½, and slower clearance were both correlated with disease stabilization and longer survival. This association of pharmacokinetic parameters with patient outcome suggests that arrest of tumor growth is related to the enhanced tumor localization of long-circulating liposomes and highlights the importance of personalized pharmacokinetic evaluation in the clinical use of nanomedicines. Another important area where PL-MLP may have an added value is in chemoradiotherapy, where it has shown a strong radiosensitizing effect in animal models based on a unique mechanism of enhanced prodrug activation and encouraging results in early human testing.

Co-delivery of dual chemo-drugs with precisely controlled, high drug loading polymeric micelles for synergistic anti-cancer therapy

Simultaneous delivery of multiple chemotherapeutics using polymeric micelles often suffers from unsatisfactory drug loading, drug ratio management, and drug release. Herein, we report a feasible strategy to prepare micelles with ultra-high drug loading and a controllable drug ratio through the introduction of donor-acceptor interactions between drugs and polymeric carriers. An amphiphilic copolymer modified with phenylboronic acid moieties on the hydrophobic segment was synthesized, in which phenylboronic acid functioned as an electron acceptor and formed donor-acceptor coordination with doxorubicin (DOX) and irinotecan (IR). The obtained dual-drug-loaded micelles possessed high drug loading (up to 50%), a tunable drug ratio, and a uniform particle size. Furthermore, both of the encapsulated drug cargoes could be effectively and selectively released in cancer cells with over-produced reactive oxygen species (ROS), and thus the drug-loaded micelles exhibited synergistic anticancer efficacy and reduced systemic toxicity.

Multitargeted Nanoparticles Deliver Synergistic Drugs across the Blood-Brain Barrier to Brain Metastases of Triple Negative Breast Cancer Cells and Tumor-Associated Macrophages

Patients with brain metastases of triple negative breast cancer (TNBC) have a poor prognosis owing to the lack of targeted therapies, the aggressive nature of TNBC, and the presence of the blood-brain barrier (BBB) that blocks penetration of most drugs. Additionally, infiltration of tumor-associated macrophages (TAMs) promotes tumor progression. Here, a terpolymer-lipid hybrid nanoparticle (TPLN) system is designed with multiple targeting moieties to first undergo synchronized BBB crossing and then actively target TNBC cells and TAMs in microlesions of brain metastases. In vitro and in vivo studies demonstrate that covalently bound polysorbate 80 in the terpolymer enables the low-density lipoprotein receptor-mediated BBB crossing and TAM-targetability of the TPLN. Conjugation of cyclic internalizing peptide (iRGD) enhances cellular uptake, cytotoxicity, and drug delivery to brain metastases of integrin-overexpressing TNBC cells. iRGD-TPLN with coloaded doxorubicin (DOX) and mitomycin C (MMC) (iRGD-DMTPLN) exhibits higher efficacy in reducing metastatic burden and TAMs than nontargeted DMTPLN or a free DOX/MMC combination. iRGD-DMTPLN treatment reduces metastatic burden by 6-fold and 19-fold and increases host median survival by 1.3-fold and 1.6-fold compared to DMTPLN or free DOX/MMC treatments, respectively. These findings suggest that iRGD-DMTPLN is a promising multitargeted drug delivery system for the treatment of integrin-overexpressing brain metastases of TNBC.

MicroRNA-222 promotes drug resistance to doxorubicin in breast cancer via regulation of miR-222/bim pathway

Resistance to doxorubicin (DOX) is the most common clinical problem in breast cancer therapy, and the underlying molecular mechanism remains to be investigated. MicroRNAs (miRNAs) exhibit important regulatory functions in various malignant tumors including breast cancer. The aim of the present study was to find the relationship between miR-222 and DOX resistance. We found that miR-222 was highly expressed in patients’ serum and DOX-resistant cell line MCF-7-R and that miR-222 could promote proliferation and migration of breast cancer cells. Our results also showed that inhibition of miR-222 in MCF-7-R significantly increased Bcl-2 interacting mediator (Bim) expression both in mRNA and protein levels by using quantitative real-time PCR (qRT-PCR) and Western blot. MTT and flow cytometry suggested that lower expressed miR-222 enhanced apoptosis and decreased IC₅₀ of MCF-7-R cells. Conversely, in MCF-7 cells transfected with miR-222 mimics, up-regulation of miR-222 was associated with decreased Bim level accompanied by less apoptosis and higher IC₅₀. Moreover, miR-222 inhibitors reversed DOX resistance via miR-222-Bim-caspase pathway. Collectively, these data first elucidated that miR-222 could function as an oncogene and was able to reduce the sensitivity of breast cancer cells to DOX through miR-222-Bim-caspase pathway, which provided a potential target to increase DOX sensitivity in clinical breast cancer treatment.

Threatening cancer with nanoparticle aided combination oncotherapy

Employing combination therapy has become obligatory in cancer cases exhibiting high tumor load, chemoresistant tumor population, and advanced disease stages. Realization of this fact has now led many of the combination oncotherapies to become an integral part of anticancer regimens. Combination oncotherapy may encompass a combination of anticancer agents belonging to a similar therapeutic category or that of different therapeutic categories (e.g. chemotherapy + gene therapy). Differences in the physicochemical properties, pharmacokinetics and biodistribution pattern of different payloads are the major constraints that are faced by combination chemotherapy. Concordant efforts in the field of nanotechnology and oncology have emerged with several approaches to solve the major issues encountered by combination therapy. Unique colloidal behaviors of various types of nanoparticles and differential targeting strategies have accorded an unprecedented ability to optimize combination oncotherapeutic delivery. Nanocarrier based delivery of the various types of payloads such as chemotherapeutic agents and other anticancer therapeutics such as small interfering ribonucleic acid (siRNA), chemosensitizers, radiosensitizers, and antiangiogenic agents have been addressed in the present review. Various nano-delivery systems like liposomes, polymeric nanoparticles, polymerosomes, dendrimers, micelles, lipid based nanoparticles, prodrug based nanocarriers, polymer-drug conjugates, polymer-lipid hybrid nanoparticles, carbon nanotubes, nanosponges, supramolecular nanocarriers and inorganic nanoparticles (gold nanoparticles, silver nanoparticles, magnetic nanoparticles and mesoporous silica based nanoparticles) that have been extensively explored for the formulation of multidrug delivery is an imperative part of discussion in the review. The present review features the outweighing benefits of combination therapy over mono-oncotherapy and discusses several existent nanoformulation strategies that facilitate a successful combination oncotherapy. Several obstacles that may impede in transforming nanotechnology-based combination oncotherapy from bench to bedside, and challenges associated therein have also been discussed in the present review.

Nanostructured Lipid Carrier Co-loaded with Doxorubicin and Docosahexaenoic Acid as a Theranostic Agent: Evaluation of Biodistribution and Antitumor Activity in Experimental Model

PURPOSE

Nanotheranostic platforms, i.e., the combination of both therapeutic and diagnostic agents on a single platform, are emerging as an interesting tool for the personalized cancer medicine. Therefore, the aim of this work was to evaluate the in vivo properties of a Tc-99m-labeled nanostructured lipid carrier (NLC) formulation, co-loaded with doxorubicin (DOX) and docosahexaenoic acid (DHA), for theranostic applications.

PROCEDURES

NLC-DHA-DOX were prepared busing the hot melting homogenization method using an emulsification-ultrasound and were radiolabeled with Tc-99m. Biodistribution studies, scintigraphic images, and antitumor activity were performed in 4T1 tumor-bearing mice.

RESULTS

NCL was successfully radiolabeled with Tc-99m. Blood clearance showed a relatively long half-life, with blood levels decaying in a biphasic manner (T_1/2 α = 38.7 min; T_1/2 β = 516.5 min). The biodistribution profile and scintigraphic images showed higher tumor uptake compared to contralateral muscle in all time-points investigated. Antitumor activity studies showed a substantial tumor growth inhibition ratio for NLC-DHA-DOX formulation. In addition, the formulation showed more favorable toxicity profiles when compared to equivalent doses of free administered drugs, being able to reduce heart and liver damage.

CONCLUSIONS

Therefore, NLC-DHA-DOX formulation demonstrated feasibility in breast cancer treatment and diagnosis/monitoring, leading to a new possibility of a theranostic platform.

In Situ Proapoptotic Peptide-Generating Rapeseed Protein-Based Nanocomplexes Synergize Chemotherapy for Cathepsin-B Overexpressing Breast Cancer

Intracellular activation of nanomaterials within cancer cells presents a powerful means to enhance anticancer specificity and efficacy. In light of upregulated lysosomal protease cathepsin-B (CathB) in many types of invasive cancer cells, herein, we exploit CathB-catalyzed biodegradation of acetylated rapeseed protein isolate (ARPI) to design polymer-drug nanocomplexes that can produce proapoptotic peptides in situ and synergize chemotherapy. ARPI forms nanocomplexes with chitosan (CS) and anticancer drug doxorubicin (DOX) [DOX-ARPI/CS nanoparticles (NPs)] by ionic self-assembly. The dual acidic pH- and CathB-responsive properties of the nanocomplexes and CathB-catalyzed biodegradation of ARPI enable efficient lysosomal escape and nuclei trafficking of released DOX, resulting in elevated cytotoxicity in CathB-overexpressing breast cancer cells. The ARPI-derived bioactive peptides exhibit synergistic anticancer effect with DOX by regulating pro- and antiapoptotic-relevant proteins ( p53, Bax, Bcl-2, pro-caspase-3) at mitochondria. In an orthotopic breast tumor model of CathB-overexpressing breast cancer, DOX-ARPI/CS NPs remarkably inhibit tumor growth, enhance tumor cell apoptosis and prolong host survival without eliciting any systemic toxicity. These results suggest that exploitation of multifunctional biomaterials to specifically produce anticancer agents inside cancer cells and trigger drug release to the subcellular target sites is a promising strategy for designing effective synergistic nanomedicines with minimal off-target toxicity.

Gastric cancer combination therapy: synthesis of a hyaluronic acid and cisplatin containing lipid prodrug coloaded with sorafenib in a nanoparticulate system to exhibit enhanced anticancer efficacy and reduced toxicity

Purpose

Gastric cancer is one of the most common human epithelial malignancies, and using nanoparticles (NPs) in the diagnosis and treatment of cancer has been extensively studied. The aim of this study was to develop hyaluronic acid (HA) containing lipid NPs coloaded with cisplatin (CDDP) and sorafenib (SRF) for the treatment of gastric cancer.

Materials and methods

HA and CDDP containing lipid prodrug was synthesized using polyethylene glycol (PEG) as a linker (HA-PEG-CDDP). HA-PEG-CDDP and SRF were entrapped into the lipid NPs by nanoprecipitation method (H-CS-NPs). The physicochemical and biochemical properties such as size, zeta potential, and drug release pattern were studied. In vitro viability was also evaluated with MKN28 and SGC7901 human gastric cancer cells. In vivo testing including biodistribution and accumulation in tumor tissue was applied in gastric tumor-bearing mice to confirm the inhibition of gastric cancer.

Results

H-CS-NP has a particle size of 173.2±5.9 nm, with a zeta potential of −21.5±3.2 mV. At day 21 of in vivo treatment, H-CS-NPs inhibited the tumor volume from 1,532.5±41.3 mm³ to 259.6±16.3 mm³ with no obvious body weight loss. In contrast, mice treated with free drugs had body weight loss from 20 to 15 g at the end of study.

Conclusion

The results indicate that H-CS-NPs enhanced the antitumor effect of drugs and reduced the systemic toxicity effects. It could be used as a promising nanomedicine for gastric cancer combination therapy.

Importance of integrating nanotechnology with pharmacology and physiology for innovative drug delivery and therapy - an illustration with firsthand examples

Nanotechnology has been applied extensively in drug delivery to improve the therapeutic outcomes of various diseases. Tremendous efforts have been focused on the development of novel nanoparticles and delineation of the physicochemical properties of nanoparticles in relation to their biological fate and functions. However, in the design and evaluation of these nanotechnology-based drug delivery systems, the pharmacology of delivered drugs and the (patho-)physiology of the host have received less attention. In this review, we discuss important pharmacological mechanisms, physiological characteristics, and pathological factors that have been integrated into the design of nanotechnology-enabled drug delivery systems and therapies. Firsthand examples are presented to illustrate the principles and advantages of such integrative design strategies for cancer treatment by exploiting 1) intracellular synergistic interactions of drug-drug and drug-nanomaterial combinations to overcome multidrug-resistant cancer, 2) the blood flow direction of the circulatory system to maximize drug delivery to the tumor neovasculature and cells overexpressing integrin receptors for lung metastases, 3) endogenous lipoproteins to decorate nanocarriers and transport them across the blood-brain barrier for brain metastases, and 4) distinct pathological factors in the tumor microenvironment to develop pH- and oxidative stress-responsive hybrid manganese dioxide nanoparticles for enhanced radiotherapy. Regarding the application in diabetes management, a nanotechnology-enabled closed-loop insulin delivery system was devised to provide dynamic insulin release at a physiologically relevant time scale and glucose levels. These examples, together with other research results, suggest that utilization of the interplay of pharmacology, (patho-)physiology and nanotechnology is a facile approach to develop innovative drug delivery systems and therapies with high efficiency and translational potential.

Ratiometric drug delivery using non-liposomal nanocarriers as an approach to increase efficacy and safety of combination chemotherapy

The observation that different drug ratios of the same drug combination can lead to synergistic or antagonistic effects when tested against the same cancer cell line in vitro gave rise to a new trend, the ratiometric delivery. This strategy consists of co-encapsulating a specific synergistic ratio of a drug combination into a nanocarrier so that synergism observed in vitro will be faithfully translated to in vivo, optimizing combination therapy. In this review we focus on how to quantify synergism in vitro, followed by how this affected the evolution of nanocarriers culminating in the ratiometric delivery, and finally we summarize the results of the non-liposomal formulations that were built upon this concept.

Sample Extraction and Simultaneous Chromatographic Quantitation of Doxorubicin and Mitomycin C Following Drug Combination Delivery in Nanoparticles to Tumor-bearing Mice

Combination chemotherapy is frequently used in the clinic for cancer treatment; however, associated adverse effects to normal tissue may limit its therapeutic benefit. Nanoparticle-based drug combination has been shown to mitigate the problems encountered by free drug combination therapy. Our previous studies have shown that the combination of two anticancer drugs, doxorubicin (DOX) and mitomycin C (MMC), produced a synergistic effect against both murine and human breast cancer cells in vitro. DOX and MMC co-loaded polymer-lipid hybrid nanoparticles (DMPLN) bypassed various efflux transporter pumps that confer multidrug resistance and demonstrated enhanced efficacy in breast tumor models. Compared to conventional solution forms, such superior efficacy of DMPLN was attributed to the synchronized pharmacokinetics of DOX and MMC and increased intracellular drug bioavailability within tumor cells enabled by the nanocarrier PLN. To evaluate the pharmacokinetics and bio-distribution of co-administered DOX and MMC in both free solution and nanoparticle forms, a simple and efficient multi-drug analysis method using reverse-phase high performance liquid chromatography (HPLC) was developed. In contrast to previously reported methods that analyzed DOX or MMC individually in the plasma, this new HPLC method is able to simultaneously quantitate DOX, MMC and a major cardio-toxic DOX metabolite, doxorubicinol (DOXol), in various biological matrices (e.g., whole blood, breast tumor, and heart). A dual fluorescent and ultraviolet absorbent probe 4-methylumbelliferone (4-MU) was used as an internal standard (I.S.) for one-step detection of multiple drug analysis with different detection wavelengths. This method was successfully applied to determine the concentrations of DOX and MMC delivered by both nanoparticle and solution approaches in whole blood and various tissues in an orthotopic breast tumor murine model. The analytical method presented is a useful tool for pre-clinical analysis of nanoparticle-based delivery of drug combinations.

Diruthenium(ii,iii) metallodrugs of ibuprofen and naproxen encapsulated in intravenously injectable polymer-lipid nanoparticles exhibit enhanced activity against breast and prostate cancer cells

A unique class of diruthenium(ii,iii) metallodrugs containing non-steroidal anti-inflammatory drug (NSAID), Ru₂(NSAID), have been reported to show anticancer activity in glioma models in vitro and in vivo. This work reports the encapsulation of the lead metallodrug of ibuprofen (HIbp), [Ru₂(Ibp)₄Cl] or RuIbp, and also of the new analogue of naproxen (HNpx), [Ru₂(Npx)₄Cl] or RuNpx, in novel intravenously (i.v.) injectable solid polymer-lipid nanoparticles (SPLNs). A rationally selected composition of lipids/polymers rendered nearly spherical Ru₂(NSAID)-SPLNs with a mean size of 120 nm and zeta potential of about -20 mV. The Ru₂(NSAID)-SPLNs are characterized by spectroscopic techniques and the composition in terms of ruthenium-drug species is analyzed by mass spectrometry. The metallodrug-loaded nanoparticles showed high drug loading (17-18%) with ∼100% drug loading efficiency, and good colloidal stability in serum at body temperature. Fluorescence-labeled SPLNs were taken up by the cancer cells in a time- and energy-dependent manner as analyzed by confocal microscopy and fluorescence spectrometry. The Ru₂(NSAID)-SPLNs showed enhanced cytotoxicity (IC₅₀ at 60-100 μmol L^-1 ) in relation to the corresponding Ru₂(NSAID) metallodrugs in breast (EMT6 and MDA-MB-231) and prostate (DU145) cancer cells in vitro. The cell viability of both metallodrug nanoformulations is also compared with those of the parent NSAIDs, HIbp and HNpx, and their corresponding NSAID-SPLNs. In vivo and ex vivo fluorescence imaging revealed good biodistribution and high tumor accumulation of fluorescence-labeled SPLNs following i.v. injection in an orthotopic breast tumor model. The enhanced anticancer activity of the metallodrug-loaded SPLNs in these cell lines can be associated with the advantages of the nanoformulations, assigned mainly to the stability of the colloidal nanoparticles suitable for i.v. injection and enhanced cellular uptake. The findings of this work encourage future in vivo efficacy studies to further exploit the potential of the novel Ru₂(NSAID)-SPLN nanoformulations for clinical application.

Dual-targeted hybrid nanoparticles of synergistic drugs for treating lung metastases of triple negative breast cancer in mice

Lung metastasis is the major cause of death in patients with triple negative breast cancer (TNBC), an aggressive subtype of breast cancer with no effective therapy at present. It has been proposed that dual-targeted therapy, ie, targeting chemotherapeutic agents to both tumor vasculature and cancer cells, may offer some advantages. The present work was aimed to develop a dual-targeted synergistic drug combination nanomedicine for the treatment of lung metastases of TNBC. Thus, Arg-Gly-Asp peptide (RGD)-conjugated, doxorubicin (DOX) and mitomycin C (MMC) co-loaded polymer-lipid hybrid nanoparticles (RGD-DMPLN) were prepared and characterized. The synergism between DOX and MMC and the effect of RGD-DMPLN on cell morphology and cell viability were evaluated in human MDA-MB-231 cells in vitro. The optimal RGD density on nanoparticles (NPs) was identified based on the biodistribution and tumor accumulation of the NPs in a murine lung metastatic model of MDA-MB-231 cells. The microscopic distribution of RGD-conjugated NPs in lung metastases was examined using confocal microscopy. The anticancer efficacy of RGD-DMPLN was investigated in the lung metastatic model. A synergistic ratio of DOX and MMC was found in the MDA-MB-231 human TNBC cells. RGD-DMPLN induced morphological changes and enhanced cytotoxicity in vitro. NPs with a median RGD density showed the highest accumulation in lung metastases by targeting both tumor vasculature and cancer cells. Compared to free drugs, RGD-DMPLN exhibited significantly low toxicity to the host, liver and heart. Compared to non-targeted DMPLN or free drugs, administration of RGD-DMPLN (10 mg/kg, iv) resulted in a 4.7-fold and 31-fold reduction in the burden of lung metastases measured by bioluminescence imaging, a 2.4-fold and 4.0-fold reduction in the lung metastasis area index, and a 35% and 57% longer median survival time, respectively. Dual-targeted RGD-DMPLN, with optimal RGD density, significantly inhibited the progression of lung metastasis and extended host survival.

Nanoformulation-based sequential combination cancer therapy

Although combining two or more treatments is regarded as an indispensable approach for effectively treating cancer, the traditional cocktail-based combination therapies are seriously limited by coordination issues that fail to account for differences in the pharmacokinetics and action sites of each drug. The careful manipulation of dosing regimens, such as by the sequential application of combination treatments, may satisfy the temporal and spatial needs of each drug and achieve successful combination antitumor therapy. Nanotechnology-based carriers might be the best tools for sequential combination therapy, as they can be loaded with multiple cargos and may provide targeted and sustained delivery to target tumor cells. Single nanoformulations capable of sequentially releasing drugs have shown synergistic anticancer activity, such as by sensitizing tumor cells through cascaded drug delivery or remodeling the tumor vasculature and microenvironment to enhance the tumor distribution of nanotherapeutics. This review highlights the use of nanotechnology-based multistage drug delivery for cancer treatment, focusing on the ability of such formulations to enhance antitumor efficacy by applying sequential treatment and modulating dosing regimens, which are challenges currently being faced in the clinic.

Design of nanocarriers for nanoscale drug delivery to enhance cancer treatment using hybrid polymer and lipid building blocks

Polymer-lipid hybrid nanoparticles (PLN) are an emerging nanocarrier platform made from building blocks of polymers and lipids. PLN integrate the advantages of biomimetic lipid-based nanoparticles (i.e. solid lipid nanoparticles and liposomes) and biocompatible polymeric nanoparticles. PLN are constructed from diverse polymers and lipids and their numerous combinations, which imparts PLN with great versatility for delivering drugs of various properties to their nanoscale targets. PLN can be classified into two types based on their hybrid nanoscopic structure and assembly methods: Type-I monolithic matrix and Type-II core-shell systems. This article reviews the history of PLN development, types of PLN, lipid and polymer candidates, fabrication methods, and unique properties of PLN. The applications of PLN in delivery of therapeutic or imaging agents alone or in combination for cancer treatment are summarized and illustrated with examples. Important considerations for the rational design of PLN for advanced nanoscale drug delivery are discussed, including selection of excipients, synthesis processes governing formulation parameters, optimization of nanoparticle properties, improvement of particle surface functionality to overcome macroscopic, microscopic and cellular biological barriers. Future directions and potential clinical translation of PLN are also suggested.

Nanomedicine of synergistic drug combinations for cancer therapy - Strategies and perspectives

Nanomedicine of synergistic drug combinations has shown increasing significance in cancer therapy due to its promise in providing superior therapeutic benefits to the current drug combination therapy used in clinical practice. In this article, we will examine the rationale, principles, and advantages of applying nanocarriers to improve anticancer drug combination therapy, review the use of nanocarriers for delivery of a variety of combinations of different classes of anticancer agents including small molecule drugs and biologics, and discuss the challenges and future perspectives of the nanocarrier-based combination therapy. The goal of this review is to provide better understanding of this increasingly important new paradigm of cancer treatment and key considerations for rational design of nanomedicine of synergistic drug combinations for cancer therapy.

Magnetoliposomes as Potential Carriers of Doxorubicin to Tumours

Studies on magnetoliposomes (MLUV) as potential carriers for magnetic-field-dependent drug delivery are presented. The systems were formed with hydrophobic superparamagnetic iron oxide nanoparticles (SPIONs) confined within the bilayer of the liposomes. The nanomechanical properties of bilayer lipid membranes were evaluated and related to the amount of incorporated SPIONs. It was found that the presence of SPIONs in the lipid membrane leads to overall stiffening and increases morphological inhomogeneity, facilitating rupture of the MLUV membrane in a low-frequency alternating magnetic field (AMF). To verify the findings, doxorubicin release from MLUVs in the presence and absence of an AMF was measured. Under experimental conditions, drug release proceeds through MLUV rupture induced by mechanical vibration of SPIONs rather than through localized heating in the vicinity of the SPIONs.

Applications of nanoparticle drug delivery systems for the reversal of multidrug resistance in cancer

Multidrug resistance (MDR) to chemotherapy presents a major obstacle in the treatment of cancer patients, which directly affects the clinical success rate of cancer therapy. Current research aims to improve the efficiency of chemotherapy, whilst reducing toxicity to prolong the lives of cancer patients. As with good biocompatibility, high stability and drug release targeting properties, nanodrug delivery systems alter the mechanism by which drugs function to reverse MDR, via passive or active targeting, increasing drug accumulation in the tumor tissue or reducing drug elimination. Given the potential role of nanodrug delivery systems used in multidrug resistance, the present study summarizes the current knowledge on the properties of liposomes, lipid nanoparticles, polymeric micelles and mesoporous silica nanoparticles, together with their underlying mechanisms. The current review aims to provide a reliable basis and useful information for the development of new treatment strategies of multidrug resistance reversal using nanodrug delivery systems.

Reduced in vivo toxicity of doxorubicin by encapsulation in cholesterol-containing self-assembled nanoparticles

We previously reported the development of an amphiphilic brush-like block copolymer composed of polynorbornene-cholesterol/polyethylene glycol (P(NBCh9-b-NBPEG)) that self-assembles in aqueous media to form long circulating nanostructures capable of encapsulating doxorubicin (DOX-NPs). Biodistribution studies showed that this formulation preferentially accumulates in tumor tissue with markedly reduced accumulation in the heart and other major organs. The aim of the current study was to evaluate the in vivo efficacy and toxicity of DOX containing self-assembled polymer nanoparticles in a mouse xenograft tumor model and compare its effects with the hydrochloride non-encapsulated form (free DOX). DOX-NPs significantly reduced the growth of tumors without inducing any apparent toxicity. Conversely, mice treated with free DOX exhibited significant weight loss, early toxic cardiomyopathy, acute toxic hepatopathy, reduced hematopoiesis and fatal toxicity. The improved safety profile of the polymeric DOX-NPs can be explained by the low circulating concentration of non-nanoparticle-associated drug as well as the reduced accumulation of DOX in non-target organs. These findings support the use of P(NBCh9-b-NBPEG) nanoparticles as delivery platforms for hydrophobic anticancer drugs intended to reduce the toxicity of conventional treatments.

Polymer-lipid hybrid nanoparticles synchronize pharmacokinetics of co-encapsulated doxorubicin-mitomycin C and enable their spatiotemporal co-delivery and local bioavailability in breast tumor

Effective combination chemotherapy requires the delivery of drugs of synergism to tumor sites while sparing normal tissues. Herein we investigated whether coencapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) achieved this goal via ratiometric drugs in an orthotopic murine breast tumor model with nanocarrier-modified biodistribution, pharmacokinetics, local bioavailability and toxicity. Fluorescence imaging revealed quickened and extended tumor uptake but reduced cardiac accumulation of DMPLN. Quantitative drug analysis demonstrated prolonged systemic circulation, increased tumor accumulation and sustained synergistic ratios of doxorubicin and mitomycin C delivered by DMPLN over 24h. Higher levels of tumor cell apoptosis and reduced organ toxicity were obtained with DMPLN compared to free drug cocktails. DMPLN released DOX in tumors more efficiently than that from liposomal doxorubicin, as evidenced by a higher extent of the metabolite, doxorubicinol. These findings substantiate the importance of rational design of nanoparticles for synergistic drug combination therapy.

FROM THE CLINICAL EDITOR

The treatment of cancer usually involves using combination chemotherapeutic agents. In adopting a nanomedicine approach, one can in theory design combination therapy consisting of drugs of synergistic activities, with the aim to target tumor specifically while minimizing systemic toxicity. The authors in this study provided evidence for this rational design by co-encapsulation of doxorubicin and mitomycin C within polymer-lipid hybrid nanoparticles (DMPLN) in a breast cancer model.

Preparation and evaluation of PCL–PEG–PCL polymeric nanoparticles for doxorubicin delivery against breast cancer

DOX-loaded polymeric NPs based on PCL–PEG–PCL triblock copolymers were successfully prepared and showed highly efficient targeting and accumulation in tumor via EPR effect. The prepared NPs would be a promising nanosized DDS for cancer therapy.

MicroRNA-101 sensitizes hepatocellular carcinoma cells to doxorubicin-induced apoptosis via targeting Mcl-1

MicroRNAs (miRNAs/miRs) are important regulators of multiple cellular processes, and their dysregulation is a common event in tumorigenesis, including the development of hepatocellular carcinoma (HCC). Studies have shown that certain miRNAs are associated with resistance to chemotherapy or drug sensitization; however, the underlying mechanisms have largely remained elusive. Multiple drug resistance is a major barrier for the treatment of advanced HCC. In the present study, miR-101 was observed to be downregulated in a panel of HCC cell lines, suggesting that it has a tumor suppressor role. Furthermore, transfection of miR-101 significantly enhanced the cytotoxicity of doxorubicin to HepG2 cells. While overexpression of miR-101 did not influence the accumulation of doxorubicin, it promoted the apoptosis-inducing effect of doxorubicin in HepG2 cells. A bioinformatics analysis predicted that miR-101 directly targeted the 3'-untranslated region of myeloid cell leukemia 1 (Mcl-1), which was verified by a luciferase reporter assay. Finally, transfection of HepG2 cells with Mcl-1 expression plasmid inhibited apoptosis caused by doxorubicin plus miR-101 expression. In conclusion, the present study showed that miR-101 is a negative regulator of Mcl-1 in HCC, and the combination of miR-101 expression with doxorubicin may represent a novel approach for the treatment of HCC.

MiR-181b promotes chemoresistance in breast cancer by regulating Bim expression

MicroRNAs are emerging as critical regulators of the initiation and progression of multiple types of human cancers, including breast cancer. In the present study, the expression of miR-181b in breast cancer patient serum and breast cancer cell lines was evaluated. It was demonstrated that the miR-181b level was significantly upregulated in patient serum and breast cancer cell lines compared with that in normal controls. The results of in vitro 3H thymidine incorporation and Transwell migration assay indicated that miR-181b overexpression markedly promoted the proliferation and metastasis of breast cancer cells. These data suggest that miR-181b is a tumor promoter in breast cancer. Furthermore, miR-181b expression was found to be upregulated in doxorubicin (DOX)-resistant T-47D cells (T-47D-R) compared with that in the parental T-47D cells, and upregulation of miR-181b expression decreased the anticancer effect of DOX in the T-47D cells. Mechanistic studies demonstrated that the Bim gene, an essential initiator of apoptosis, was inhibited by miR-181b overexpression. We observed that knockdown of miR-181b by its specific inhibitors significantly re-sensitized the T-47D-R cells to the cytotoxicity of DOX. Importantly, we demonstrated that miR-181b inhibitors increased the level of Bim in the T-47D-R cells, resulting in the loss of mitochondrial membrane potential (MMP) and the activation of caspases caused by DOX. In summary, the results of the present study suggest that miR-181b functions as an oncogene during breast cancer development, and the miR-181b/Bim pathway may be a novel target used to overcome the chemoresistance in breast cancer.

Targeting cancer cells in the tumor microenvironment: opportunities and challenges in combinatorial nanomedicine

Cancer therapies of the future will rely on synergy between drugs delivered in combination to achieve both maximum efficacy and decreased toxicity. Nanoscale drug delivery vehicles composed of highly tunable nanomaterials ('nanocarriers') represent the most promising approach to achieve simultaneous, cell-selective delivery of synergistic ratios of combinations of drugs within solid tumors. Nanocarriers are currently being used to co-encapsulate and deliver synergistic ratios of multiple anticancer drugs to target cells within solid tumors. Investigators exploit the unique environment associated with solid tumors, termed the tumor microenvironment (TME), to make 'smart' nanocarriers. These sophisticated nanocarriers exploit the pathological conditions in the TME, thereby creating highly targeted nanocarriers that release their drug payload in a spatially and temporally controlled manner. The translational and commercial potential of nanocarrier-based combinatorial nanomedicines in cancer therapy is now a reality as several companies have initiated human clinical trials.

The role of miR-125b-mitochondria-caspase-3 pathway in doxorubicin resistance and therapy in human breast cancer

MicroRNAs (miRNAs) are a class of naturally occurring, small, non-coding RNAs which play important roles in diverse biological processes and are acting as key regulators of tumorigenesis and chemotherapy resistance. In this study, a downregulation of miR-125b was observed in breast cancer cell lines, suggesting miR-125b is a tumor suppressor in breast cancer. Moreover, the miR-125b levels were significantly decreased in doxorubicin-resistant MCF-7 (MCF-7/DR) cells compared with MCF-7 cells. Transfection of miR-125b significantly enhanced the cytotoxicity of doxorubicin to MCF-7/DR cells. However, the overexpression of miR-125b did not influence the doxorubicin accumulation but downregulated the myeloid cell leukemia-1 (Mcl-1) levels, which may be the mechanism of apoptosis induction caused by doxorubicin combining with miR-125b in MCF-7/DR cells. Furthermore, luciferase reporter assay proved that Mcl-1 is the target of miR-125b. Importantly, we found that the sensitization of miR-125b to doxorubicin cytotoxicity is caspase-dependent in MCF-7/DR cells, which can be inhibited by zVAD-fmk. Finally, we indicated that the treatment of miR-125b plus doxorubicin leads to loss of mitochondrial membrane potential (MMP) and mitochondria outer membrane permeability (MOMP), which were interacted with the activation of caspases. Thus, this study revealed the role of miR-125b in doxorubicin resistance and therapy, which may provide novel approaches for the treatment of breast cancer.

Optimizing the design and in vitro evaluation of bioreactive glucose oxidase-microspheres for enhanced cytotoxicity against multidrug resistant breast cancer cells

Glucose oxidase (GOX) encapsulated in alginate-chitosan microspheres (GOX-MS) was shown in our previous work to produce reactive oxygen species (ROS) in situ and exhibit anticancer effects in vitro and in vivo. The purpose of present work was to optimize the design and thus enhance the efficacy of GOX-MS against multidrug resistant (MDR) cancer cells. GOX-MS with different mean diameters of 4, 20 or 140 μm were prepared using an emulsification-internal gelation-adsorption-chitosan coating method with varying compositions and conditions. The GOX loading efficiency, loading level, relative bioactivity of GOX-MS, and GOX leakage were determined and optimal chitosan concentrations in the coating solution were identified. The influence of particle size on cellular uptake, ROS generation, cytotoxicity and their underlying mechanisms was investigated. At the same GOX dose and incubation time, smaller sized GOX-MS produced larger amounts of H2O2 in cell culture medium and greater cytotoxicity toward murine breast cancer MDR (EMT6/AR1.0) and wild type (EMT6/WT) cells. Fluorescence and confocal laser scanning microscopy revealed significant uptake of small sized (4 μm) GOX-MS by both MDR and WT cells, but no cellular uptake of large (140 μm) GOX-MS. The GOX-MS were equally effective in killing both MDR cells and WT cells. The cytotoxicity of the GOX formulations was positively correlated with membrane damage and lipid peroxidation. GOX-MS induced greater membrane damage and lipid peroxidation in MDR cells than the WT cells. These results suggest that the optimized, small micron-sized GOX-MS are highly effective against MDR breast cancer cells.

Coencapsulated doxorubicin and bromotetrandrine lipid nanoemulsions in reversing multidrug resistance in breast cancer in vitro and in vivo

Multidrug resistance has remained a major cause of treatment failure in chemotherapy due to the presence of P-glycoproteins (P-gp) that actively pump drugs from inside the cell to the outside. P-gp inhibitors were developed and coadministered with chemotherapeutic drugs to overcome the effect of efflux pumps thus enhancing the chemosensitivity of therapeutics. Our study aimed at developing a lipid nanoemulsion system for the coencapsulation of doxorubicin (DOX) and bromotetrandrine (W198) to reverse multidrug resistance (MDR) in breast cancer. W198 was a potent P-gp inhibitor, and DOX was selected as a model compound which is a common substrate for P-gp. Coencapsulated DOX and W198 lipid nanoemulsions (DOX/W198-LNs) displayed significantly enhanced cytotoxicity in DOX-resistant human breast cancer cells (MCF-7/ADR) compared with DOX loaded lipid nanoemulsions (DOX-LNs) (p < 0.05), which is due to the enhanced intracellular uptake of DOX in MCF-7/ADR cells. The biodistribution study was performed using a nude mice xenograft model, which demonstrates enhanced tumor uptake of DOX in the DOX/W198-LN treated group. Compared with DOX solution, DOX/W198-LNs showed reduced cardiac toxicity and gastrointestinal injury in rats. Taken together, DOX/W198-LNs represent a promising formulation for overcoming MDR in breast cancer.