A nanoparticulate pre-chemosensitizer for efficacious chemotherapy of multidrug resistant breast cancer

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.

A facile, flexible, and multifunctional thermo-chemotherapy system for customized treatment of drug-resistant breast cancer

Anticancer drug resistance invariably emerges and poses a significant barrier to curative therapy for various breast cancers. This results in a lack of satisfactory therapeutic medicine for cancer treatment. Herein, a universal vector system for drug-resistance breast cancer was designed to meet the needs of reversed multidrug resistance, thermo-chemotherapy, and long-term drug release behavior. The vector system comprises polycaprolactone (PCL) nanofiber mesh and magnetic nanoparticles (MNPs). PCL has excellent biocompatibility and electrospinning performance. In this study, MNPs were tailored to be thermogenic in response to an alternating magnetic field (AMF). PCL nanofiber can deliver various chemotherapy drugs, and suitable MNPs encapsulated in the nanofiber can generate hyperthermia and synergistic effect with those chemotherapy drugs. Therefore, a more personalized treatment system can be developed for different breast malignancies. In addition, the PCL nanofiber mesh (NFM) enables sustained release of the drugs for up two months, avoiding the burden on patients caused by repeated administration. Through model drugs doxorubicin (DOX) and chemosensitizers curcumin (CUR), we systematically verified the therapeutic effect of DOX-resistance breast cancer and inhibition of tumor generation in vivo. These findings represent a multifaceted platform of importance for validating strategic reversed MDR in pursuit of promoted thermo-chemotherapeutic outcomes. More importantly, the low cost and excellent safety and efficacy of this nanofiber mesh demonstrate that this can be customized multi-function vector system may be a promising candidate for refractory cancer therapy in clinical.

Influence of the microbiota on the effectiveness and toxicity of oncological therapies, with a focus on chemotherapy

Recent studies have highlighted a possible correlation between microbiota composition and the pathogenesis of various oncological diseases. Also, many bacterial groups are now directly or indirectly associated with the capability of stimulating or inhibiting carcinogenic pathways. However, little is known about the importance and impact of microbiota patterns related to the efficacy and toxicity of cancer treatments. We have recently begun to understand how oncological therapies and the microbiota are closely interconnected and could influence each other. Chemotherapy effectiveness, for example, appears to be strongly influenced by the presence of some microorganisms capable of modulating the pharmacokinetics and pharmacodynamics of the compounds used, thus varying the real response and therefore the efficacy of the oncological treatment. Similarly, chemotherapeutic agents can modulate the microbiota with variations that could facilitate or avoid the onset of important side effects. This finding has or could have considerable relevance as it is possible that our ability to modulate and modify the microbial structure before, during, and after treatment could influence all the clinical parameters related to pharmacological treatments and, eventually, the prognosis of the disease.

Size-Controlled Preparation of Docetaxel- and Curcumin-Loaded Nanoemulsions for Potential Pulmonary Delivery

Lung cancer is one of the deadliest pulmonary diseases in the world. Although docetaxel (DTX) has exhibited superior efficacy in lung cancer treatment, it has demonstrated numerous adverse effects and poor bioavailability. The natural product extract, curcumin (CCM), has reportedly reduced toxicity and synergistically improved DTX bioavailability. Nonetheless, the hydrophobic nature of DTX and CCM limits their clinical use. Nanoemulsion pulmonary delivery of DTX and CCM has demonstrated potential as a drug carrier to alleviate these drawbacks. The controlled preparation of inhalable DTX- and CCM-loaded nanoemulsions within the 100 to 200 nm range was explored in this study. A response surface methodology (RSM) based on a central composite design (CCD) was utilized to fabricate the desired size of the nanoemulsion under optimized conditions. Different process parameters were employed to control the size of the nanoemulsions procured through a high-energy emulsification technique. The size of the resultant nanoemulsions decreased with increasing energy input. The actual response according to the targeted sizes for DTX- and CCM-loaded nanoemulsion models exhibited excellent agreement with the predicted value at below 5% residual standard error under optimized conditions. The nanoemulsion of 100 nm particle size demonstrated better membrane permeability than their larger counterparts. Moreover, the formulations documented favorable physicochemical and aerodynamic pulmonary delivery properties and reduced toxicity in human lung fibroblast (MRC-5) cells. Hence, this tunable size of nanoemulsions could be a suitable alternative drug delivery for pulmonary diseases with increased local lung concentration.

Phytochemical Targeting of Mitochondria for Breast Cancer Chemoprevention, Therapy, and Sensitization

Breast cancer is a common and deadly disease that causes tremendous physical, emotional, and financial burden on patients and society. Early-stage breast cancer and less aggressive subtypes have promising prognosis for patients, but in aggressive subtypes, and as cancers progress, treatment options and responses diminish, dramatically decreasing survival. Plants are nutritionally rich and biologically diverse organisms containing thousands of metabolites, some of which have chemopreventive, therapeutic, and sensitizing properties, providing a rich source for drug discovery. In this study we review the current landscape of breast cancer with a central focus on the potential role of phytochemicals for treatment, management, and disease prevention. We discuss the relevance of phytochemical targeting of mitochondria for improved anti-breast cancer efficacy. We highlight current applications of phytochemicals and derivative structures that display anti-cancer properties and modulate cancer mitochondria, while describing future applicability and identifying areas of promise.

Vitamin-H Channeled Self-Therapeutic P-gp Inhibitor Curcumin-Derived Nanomicelles for Targeting the Tumor Milieu by pH- and Enzyme-Triggered Hierarchical Disassembly

An effective nanocarrier-mediated drug delivery to cancer cells primarily faces limitations like the presence of successive drug delivery barriers, insufficient circulation time, drug leakage, and decreased tumor penetration capacity. With the aim of addressing this paradox, a self-therapeutic, curcumin-derived copolymer was synthesized by conjugation with PEGylated biotin via enzyme- and acid-labile ester and acetal linkages. This copolymer is a prodrug of curcumin and self-assembles into ∼150-200 nm-sized nanomicelles; it is capable of encapsulating doxorubicin (DOX) and hence can be designated as self-therapeutic. pH- and enzyme-responsive linkages in the polymer skeleton assist in its hierarchical disassembly only in the tumor microenvironment. Further, the conjugation of biotin and poly(ethylene glycol) (PEG) imparts features of tumor specificity and improved circulation times to the nanocarrier. The dynamic light scattering (DLS) analysis supports this claim and demonstrates rapid swelling and disruption of micelles under acidic pH. UV-vis spectroscopy provided evidence of an accelerated acetal degradation at pH 4.0 and 5.0. The in vitro release studies revealed a controlled release of DOX under acidic conditions and curcumin release in response to the enzyme. The value of the combination index calculated on HepG2 cells was found to be <1, and hence, the drug pair curcumin and DOX acts synergistically for tumor regression. To prove the efficiency of acid-labile linkages and the prodrug strategy for effective cancer therapy, curcumin-derived polymers devoid of sensitive linkages were also prepared. The prodrug stimuli-responsive nanomicelles showed enhanced cell cytotoxicity and tumor penetration capability on HepG2 cells as well as drug-resistant MCF-7 cell lines and no effect on normal NIH/3T3 fibroblasts as compared to the nonresponsive micelles. The results were also supported by in vivo evidence on a hepatocellular carcinoma (HCC)-induced nude mice model. An evident decrease in MMP-2, MMP-9, and α-fetoprotein (AFP), the biomarkers specific to tumor progression, was observed along with metastasis upon treatment with the drug-loaded dual-responsive nanomicelles. These observations corroborated with the SGOT and SGPT data as well as the histoarchitecture of the liver tissue in mice.

Exploring new Horizons in overcoming P-glycoprotein-mediated multidrug-resistant breast cancer via nanoscale drug delivery platforms

The high probability (13%) of women developing breast cancer in their lifetimes in America is exacerbated by the emergence of multidrug resistance after exposure to first-line chemotherapeutic agents. Permeation glycoprotein (P-gp)-mediated drug efflux is widely recognized as the major driver of this resistance. Initial in vitro and in vivo investigations of the co-delivery of chemotherapeutic agents and P-gp inhibitors have yielded satisfactory results; however, these results have not translated to clinical settings. The systemic delivery of multiple agents causes adverse effects and drug-drug interactions, and diminishes patient compliance. Nanocarrier-based site-specific delivery has recently gained substantial attention among researchers for its promise in circumventing the pitfalls associated with conventional therapy. In this review article, we focus on nanocarrier-based co-delivery approaches encompassing a wide range of P-gp inhibitors along with chemotherapeutic agents. We discuss the contributions of active targeting and stimuli responsive systems in imparting site-specific cytotoxicity and reducing both the dose and adverse effects.

Reversing Chemotherapy Resistance by a Synergy between Lysosomal pH-Activated Mitochondrial Drug Delivery and Erlotinib-Mediated Drug Efflux Inhibition

Mitochondrial drug delivery has attracted increasing attention in various mitochondrial dysfunction-associated disorders such as cancer owing to the important role of energy production. Herein, we report a lysosomal pH-activated mitochondrial-targeting polymer nanoparticle to overcome drug resistance by a synergy between mitochondrial delivery of doxorubicin (DOX, an anticancer drug) and erlotinib-mediated inhibition of drug efflux. The obtained nanoparticles, DE-NPs could maintain negative charge and have long blood circulation while undergoing charge reversal at lysosomal pH after internalization by cancer cells. Thereafter, the acidity-activated polycationic and hydrophobic polypeptide domains boost lysosomal escape and mitochondrial-targeting drug delivery, leading to mitochondrial dysfunction, ATP suppression, and cell apoptosis. Moreover, the suppressed ATP supply and erlotinib enabled dual inhibition of drug efflux by DOX-resistant MCF-7/ADR cells, leading to significantly augmented intracellular DOX accumulation and a synergistic anticancer effect with a 17-fold decrease of IC50 relative to DOX. In vivo antitumor study demonstrates that DE-NPs efficiently suppressed the tumor burden in MCF-7/ADR tumor-bearing mice and led to negligible toxicity. This work establishes that a combination of mitochondrial drug delivery and drug efflux inhibition could be a promising strategy for combating multidrug resistance.

Drug Resistance in Metastatic Breast Cancer: Tumor Targeted Nanomedicine to the Rescue

Breast cancer, specifically metastatic breast, is a leading cause of morbidity and mortality in women. This is mainly due to relapse and reoccurrence of tumor. The primary reason for cancer relapse is the development of multidrug resistance (MDR) hampering the treatment and prognosis. MDR can occur due to a multitude of molecular events, including increased expression of efflux transporters such as P-gp, BCRP, or MRP1; epithelial to mesenchymal transition; and resistance development in breast cancer stem cells. Excessive dose dumping in chemotherapy can cause intrinsic anti-cancer MDR to appear prior to chemotherapy and after the treatment. Hence, novel targeted nanomedicines encapsulating chemotherapeutics and gene therapy products may assist to overcome cancer drug resistance. Targeted nanomedicines offer innovative strategies to overcome the limitations of conventional chemotherapy while permitting enhanced selectivity to cancer cells. Targeted nanotheranostics permit targeted drug release, precise breast cancer diagnosis, and importantly, the ability to overcome MDR. The article discusses various nanomedicines designed to selectively target breast cancer, triple negative breast cancer, and breast cancer stem cells. In addition, the review discusses recent approaches, including combination nanoparticles (NPs), theranostic NPs, and stimuli sensitive or “smart” NPs. Recent innovations in microRNA NPs and personalized medicine NPs are also discussed. Future perspective research for complex targeted and multi-stage responsive nanomedicines for metastatic breast cancer is discussed.

Efficacy of topotecan nanoparticles for intravitreal chemotherapy of retinoblastoma

Retinoblastoma (Rb) is the most common intraocular malignancy in children that accounts for approximately 4% of all pediatric malignancies. Since chemotherapy is a widely practiced treatment for Rb, there is a growing interest in developing new and effective drugs to overcome systemic and local side effects of chemotherapy to improve the quality of life and increase the chances of survival. This study sought to fabricate thiolated chitosan nanoparticles containing topotecan (TPH-TCs-NPs) with a view of enhancing drug loading and release control. This research was also designed to assess the ability of TPH-TCs-NPs to improve cell association, increase treatment efficacy in retinoblastoma cells and xenograft-rat-model of retinoblastoma, and overcome current topotecan hydrochloride (TPH) intravitreal administration challenges, including stability loss and poor cellular uptake. Modified ionic gelation method was optimized to fabricate TPH-TCs-NPs and TPH-TMC-NPs (N-trimethyl chitosan nanoparticles containing TPH). We characterized the NPs and quantified topotecan loading and release against a free TPH standard. The efficacy of TPH-NPs was quantified in human retinoblastoma cells (Y79) by XTT and flow cytometry measurement. In addition, Y79 cells were injected intravitreally in both eyes of immunodeficient wistar albino rats to create a xenograft-rat-model to compare the antitumor effectiveness of TPH-NPs and TPH by intravitreal administration. TPH-NPs complexation was confirmed by EDX, FTIR, and DSC techniques. TPH-TCs-NPs and TPH-TMC-NPs had high encapsulation efficiency (85.23 ± 2 and 73.34 ± 2% respectively). TPH-TCs-NPs showed a mean diameter, polidispersity index, and zeta potential of 25±2 nm, 0.21 ± 0.03 and +12 ± 2 mV, respectively. As a function of dose, TCs and TMC NPs were more efficacious than free topotecan (IC50s 53.17 and 85.88 nM, relative to 138.30 nM respectively, P = 0.012). Kruskal-Wallis test showed a statistically significant difference between the groups. Additionally, a significant difference between the tumor control and TPH-TCs-NPs treated group in xenograft-rat-model ( Range of P-value: 0.026 to 0.035) was shown by Bonferroni post hoc test. The current investigation demonstrated enhanced efficacy and association of TPH-TCs-NPs relative to free TPH in retinoblastoma cells and tumor in vitro and in vivo.

Breast Cancer Targeted Treatment Strategies: Promising Nanocarrier Approaches

Breast cancer is the second most common cancer that causes death among women worldwide. Incidence of breast cancer is increasing worldwide, and the age at which breast cancer develops has shifted from 50- 70 years to 30-40 years. Chemotherapy is the most commonly used effective treatment strategy to combat breast cancer. However, one of the major drawbacks is low selective site-specificity and the consequent toxic insult to normal healthy cells. The nanocarrier system is consistently utilised to minimise the various limitations involved in the conventional treatment of breast cancer. The nanocarrier based targeted drug delivery system provides better bioavailability, prolonged circulation with an effective accumulation of drugs at the tumour site either by active or passive drug targeting. Active targeting has been achieved by receptor/protein anchoring and externally guided magnetic nanocarriers, whereas passive targeting accomplished by employing the access to the tunnel via leaky tumour vasculature, utilising the tumour microenvironment, because the nanocarrier systems can reduce the toxicity to normal cells. As of now a few nanocarrier systems have been approved by FDA, and various nanoformulations are in the pipeline at the preclinical and clinical development for targeting breast cancer; among them, polymeric micelles, microemulsions, magnetic microemulsions, liposomes, dendrimers, carbon nanotubes, and magnetic Nanoparticles (NPs) are the most common. The current review highlights the active and passive targeting potential of nanocarriers in breast cancer and discusses their role in targeting breast cancer without affecting normal healthy cells.

Achillin Increases Chemosensitivity to Paclitaxel, Overcoming Resistance and Enhancing Apoptosis in Human Hepatocellular Carcinoma Cell Line Resistant to Paclitaxel (Hep3B/PTX)

Multidrug resistance (MDR) has become a major obstacle in the treatment of cancer, and is associated with mechanisms such as increased drug outflow, reduction of apoptosis, and/or altered drug metabolism. These problems can be mitigated by the coadministration of agents known as chemosensitizers, as they can reverse resistance to anticancer drugs and eventually resensitize cancer cells. We explore the chemosensitizing effect of Achillin, a guaianolide-type sesquiterpene lactone isolated from the Mexican medicinal plant Artemisia ludovisiana, to reverse MDR in Hep3B/PTX cells of hepatocellular carcinoma, which present resistance to paclitaxel (PTX). Achillin showed an important effect as chemosensitizer; indeed, the cytotoxic effect of PTX (25 nM) was enhanced, and the induction of G2/M phase cell cycle arrest and apoptosis were potentiated when combining with Achillin (100 μM). In addition, we observed that Achillin decreases P-gp levels and increases the intracellular retention of doxorubicin in Hep3B/PTX cells; in addition, homology structural modeling and molecular docking calculations predicted that Achillin interacts in two regions (M-site and R-site) of transporter drug efflux P-glycoprotein (P-gp). Our results suggest that the chemosensitizer effect demonstrated for Achillin could be associated with P-gp modulation. This work also provides useful information for the development of new therapeutic agents from guaianolide-type sesquiterpene lactones like Achillin.

ABC Transporter-Mediated Multidrug-Resistant Cancer

ATP-binding cassette (ABC) transporters are involved in active pumping of many diverse substrates through the cellular membrane. The transport mediated by these proteins modulates the pharmacokinetics of many drugs and xenobiotics. These transporters are involved in the pathogenesis of several human diseases. The overexpression of certain transporters by cancer cells has been identified as a key factor in the development of resistance to chemotherapeutic agents. In this chapter, the localization of ABC transporters in the human body, their physiological roles, and their roles in the development of multidrug resistance (MDR) are reviewed. Specifically, P-glycoprotein (P-GP), multidrug resistance-associated proteins (MRPs), and breast cancer resistance protein (BCRP/ABCG2) are described in more detail. The potential of ABC transporters as therapeutic targets to overcome MDR and strategies for this purpose are discussed as well as various explanations for the lack of efficacy of ABC drug transporter inhibitors to increase the efficiency of chemotherapy.

A Versatile Carbon Monoxide Nanogenerator for Enhanced Tumor Therapy and Anti-Inflammation

Carbon monoxide (CO) is regarded as a potential therapeutic agent with multiple beneficial functions for biomedical applications. In this study, a versatile CO nanogenerator (designated as PPOSD) was fabricated and developed for tumor therapy and anti-inflammation. Partially oxidized tin disulfide (SnS₂) nanosheets (POS NSs) were decorated with a tumor-targeting polymer (polyethylene glycol-cyclo(Asp-d-Phe-Lys-Arg-Gly), PEG-cRGD), followed by the loading of chemotherapeutic drug doxorubicin (DOX) to prepare polymer@POS@DOX, or PPOSD. After injected intravenously, PPOSD could selectively accumulate in tumor tissue via the cRGD-mediated tumor recognition. Upon 561 nm laser irradiation, the POS moiety in PPOSD can photoreduce CO₂ to CO, which significantly sensitized the chemotherapeutic effect of DOX. The POS in PPOSD can also act as a photothermal agent for effective photothermal therapy (PTT) of the tumor upon 808 nm laser irradiation. Furthermore, the generated CO can simultaneously decrease the inflammatory reaction caused by PTT. Blood analysis and hematoxylin-eosin staining of major organs showed that no obvious systemic toxicity was induced after the treatment, suggesting good biosafety of PPOSD. This versatile CO nanogenerator will find great potential for both enhanced tumor inhibition and anti-inflammation.

Cationic block amphiphiles show anti-mitochondrial activity in multi-drug resistant breast cancer cells

Currently, there are limited treatment options for multi-drug resistant breast cancer. Lipid-modified cationic peptides have the potential to reach the mitochondria, which are attractive targets for the treatment of multi-drug resistant (MDR) breast cancer; yet, little is known about their mitochondrial targeting and anti-cancer activity. Interestingly, lipid-modified cationic peptides, typically used as gene transfection agents, exhibit similar structural features to mitochondrial targeted peptides. Using octahistidine-octaarginine (H₈R₈) as a model cationic peptide for cell penetration and endosomal escape, we explored the anti-cancer potential of lipid-modified cationic peptides as a function of amphiphilicity, biodegradability and lipid structure. We found that cationic peptides modified with a lipid that is at least 12 carbons in length exhibit potent anti-cancer activity in the low micromolar range in both EMT6/P and EMT6/AR-1 breast cancer cells. Comparing degradable and non-degradable linkers, as well as L- and D-amino acid sequences, we found that the anti-cancer activity is mostly independent of the biodegradation of the lipid-modified cationic peptides. Two candidates, stearyl-H₈R₈ (Str-H₈R₈) and vitamin E succinate-H₈R₈ (VES-H₈R₈) were cytotoxic to cancer cells by mitochondria depolarization. We observed increased reactive oxygen species (ROS) production, reduced cell bioenergetics and drug efflux, triggering apoptosis and G1 cell cycle arrest. Compared to Str-H₈R₈, VES-H₈R₈ showed enhanced cancer cell selectivity and drug efflux inhibition, thereby serving as a potential novel therapeutic agent. This study deepens our understanding of lipid-modified cationic peptides and uncovers their potential in multi-drug resistant breast cancer.

Delivering Combination Chemotherapies and Targeting Oncogenic Pathways via Polymeric Drug Delivery Systems

The side-effects associated with chemotherapy necessitates better delivery of chemotherapeutics to the tumor. Nanoparticles can load higher amounts of drug and improve delivery to tumors, increasing the efficacy of treatment. Polymeric nanoparticles, in particular, have been used extensively for chemotherapeutic delivery. This review describes the efforts made to deliver combination chemotherapies and inhibit oncogenic pathways using polymeric drug delivery systems. Combinations of chemotherapeutics with other drugs or small interfering RNA (siRNA) combinations have been summarized. Special attention is given to the delivery of drug combinations that involve either paclitaxel or doxorubicin, two popular chemotherapeutics in clinic. Attempts to inhibit specific pathways for oncotherapy have also been described. These include inhibition of oncogenic pathways (including those involving HER2, EGFR, MAPK, PI3K/Akt, STAT3, and HIF-1α), augmentation of apoptosis by inhibiting anti-apoptosis proteins (Bcl-2, Bcl-xL, and survivin), and targeting dysregulated pathways such as Wnt/β-catenin and Hedgehog.

Systemic siRNA delivery to tumors by cell-penetrating α-helical polypeptide-based metastable nanoparticles

Systemic, non-viral siRNA delivery for cancer treatment is mainly achieved via condensation by cationic materials (e.g., lipids and cationic polymers), which nevertheless, suffers from poor serum stability, non-specific tissue interaction, and unsatisfactory membrane activity against efficient in vivo gene knockdown. Here, we report the design of a metastable, cancer-targeting siRNA delivery system based on two functional polymers, PVBLG-8, a cationic, helical cell-penetrating polypeptide, and poly(l-glutamic acid) (PLG), an anionic random-coiled polypeptide. PVBLG-8 with rigid, linear structure showed weak siRNA condensation capability, and PLG with flexible chains was incorporated as a stabilizer which provided sufficient molecular entanglement with PVBLG-8 to encapsulate the siRNA within the polymeric network. The obtained PVBLG-8/siRNA/PLG nanoparticles (PSP NPs) with positive charges were sequentially coated with additional amount of PLG, which reversed the surface charge from positive to negative to yield the metastable PVBLG-8/siRNA/PLG@PLG (PSPP) NPs. The PSPP NPs featured desired serum stability during circulation to enhance tumor accumulation via the enhanced permeability and retention (EPR) effect. Upon acidification in the tumor extracellular microenvironment and intracellular endosomes, the partial protonation of PLG on PSPP NPs surface would lead to dissociation of PLG coating from NPs, exposure of the highly membrane-active PVBLG-8, and surface charge reversal from negative to positive, which subsequently promoted tumor penetration, selective cancer cell internalization, and efficient endolysosomal escape. When siRNA against epidermal growth factor receptor (EGFR) was encapsulated, the PSPP NPs showed excellent tumor penetration capability, tumor cell uptake level, EGFR silencing efficiency, and tumor growth inhibition efficacy in U-87 MG glioblastoma tumor spheroids in vitro and in xenograft tumor-bearing mice in vivo, outperforming the PSP NPs and several commercial reagents such as Lipofectamine 2000 and poly(l-lysine) (PLL). This study therefore demonstrates a facile and unique design approach of metastable and charge reversal NPs, which overcomes multiple biological barriers against systemic siRNA delivery toward anti-cancer treatment.

Orthogonal self-assembly of an organoplatinum(II) metallacycle and cucurbit[8]uril that delivers curcumin to cancer cells

Curcumin (Cur) is a naturally occurring anticancer drug isolated from the Curcuma longa plant. It is known to exhibit anticancer properties via inhibiting the STAT3 phosphorylation process. However, its poor water solubility and low bioavailability impede its clinical application. Herein, we used organoplatinum(II) ← pyridyl coordination-driven self-assembly and a cucurbit[8]uril (CB[8])-mediated heteroternary host-guest complex formation in concert to produce an effective delivery system that transports Cur into the cancer cells. Specifically, a hexagon 1, containing hydrophilic methyl viologen (MV) units and 3,4,5-Tris[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]benzoyl groups alternatively at the vertices, has been synthesized and characterized by several spectroscopic techniques. The MV units of 1 underwent noncovalent complexation with CB[8] to yield a host-guest complex 4. Cur can be encapsulated in 4, via a 1:1:1 heteroternary complex formation, resulting in a water-soluble host-guest complex 5. The host-guest complex 5 exhibited ca 100-fold improved IC₅₀ values relative to free Cur against human melanoma (C32), melanoma of rodents (B16F10), and hormone-responsive (MCF-7) and triple-negative (MDA-MB231) breast cancer cells. Moreover, strong synergisms of Cur with 1 and 4 with combinatorial indexes of <1 across all of the cell lines were observed. An induced apoptosis with fragmented DNA pattern and inhibited expression of phosphor-STAT3 supported the improved therapeutic potential of Cur in heteroternary complex 5.

Glutathione detonated and pH responsive nano-clusters of Au nanorods with a high dose of DOX for treatment of multidrug resistant cancer

Effects of nanosized drug delivery systems on cancer are often compromised due to their low drug loadings, premature drug release and multi-drug resistance (MDR). Herein, we reported a glutathione detonated and pH responsive nano-cluster of Au nanorods (AuNRs) with chemotherapeutic doxorubicin (DOX) and pre-chemosensitizer polycurcumin to treat MCF-7/ADR cells. The nano-cluster was prepared by self-assembling of AuNRs conjugated with DOX and amphiphilic poly(curcumin-co-dithiodipropionic acid)-b-biotinylated poly(ethylene glycol) via an emulsion/solvent evaporation technique, termed AuNR Cluster. The AuNR Cluster had a high drug loading (31.5% DOX), presenting much better aqueous solubility and stability at physiological pH than their individual AuNRs. The AuNR Cluster could be detonated to be their individual AuNRs at an intracellular concentration level of glutathione (GSH) (5 mM) and triggered to release DOX at an acidic pH (pH 6.8 or 5.0), which effectively facilitated cellular uptake of DOX (607 vs 356 a.u. for AuNRs at 12 h) and inhibited DOX efflux (471.33 vs 39.17 a.u. for free DOX at 24 h). The IC₅₀ value of DOX against MCF-7/ADR cells for AuNR Cluster was 4.15 µg/mL, much lower than that for free DOX (90.97 µg/mL). The AuNR Cluster took much more photothermal effects than their corresponding AuNRs and presented enhanced anti-tumor effect (IC₅₀: 2.61 µg/mL) under 808 nm laser irradiation.

STATEMENT OF SIGNIFICANCE

Nano-sized drug delivery systems for anti-MDR cancer is still a challenging task. Herein, AuNR Cluster was self-assembled by individual AuNRs via emulsion/solvent evaporation technique, having a structure consisting of hydrophobic DOX/PCDA-AuNR core and hydrophilic biotin-PEG chain shell. AuNR Cluster is detonated to disintegrate and yield its individual AuNRs at an intracellular concentration level of glutathione (5 mM) and triggered to release DOX at an acidic pH (6.8 or 5.0). In comparison with its individual AuNRs, AuNR Cluster has better water solubility and stability, greater photothermal effects under NIR irradiation, bigger cytotoxicity against MCF-7/ADR cells. AuNR Cluster is expected to be a potential nanomedicine for treatment of MDR cancer.

Rational Design of Multifunctional Polymeric Nanoparticles Based on Poly(l-histidine) and d-α-Vitamin E Succinate for Reversing Tumor Multidrug Resistance

A multifunctional nanoparticulate system composed of methoxy poly(ethylene glycol)-poly(l-histidine)-d-α-vitamin E succinate (MPEG-PLH-VES) copolymers for encapsulation of doxorubicin (DOX) was elaborated with the aim of circumventing the multidrug resistance (MDR) in breast cancer treatment. The MPEG-PLH-VES nanoparticles (NPs) were subsequently functionalized with biotin motif for targeted drug delivery. The MPEG-PLH-VES copolymer exerts no obvious effect on the P-gp expression level of MCF-7/ADR but exhibited a significant influence on the loss of mitochondrial membrane potential, the reduction of intracellular ATP level, and the inhibition of P-gp ATPase activity of MCF-7/ADR cells. The constructed MPEG-PLH-VES NPs exhibited an acidic pH-induced increase on particle size in aqueous solution. The DOX-encapsulated MPEG-PLH-VES/biotin-PEG-VES (MPEG-PLH-VES/B) NPs were characterized to possess high drug encapsulation efficiency of approximate 90%, an average particle size of approximately 130 nm, and a pH-responsive drug release profile in acidic milieu. Confocal laser scanning microscopy (CLSM) investigations revealed that the DOX-loaded NPs resulted in an effective delivery of DOX into MCF-/ADR cells and a notable carrier-facilitated escape from endolysosomal entrapment. Pertaining to the in vitro cytotoxicity evaluation, the DOX-loaded MPEG-PLH-VES/B NPs resulted in more pronounced cytotoxicity to MCF-/ADR cells compared with DOX-loaded MPEG-PLH-VES NPs and free DOX solution. In vivo imaging study in MCF-7/ADR tumor-engrafted mice exhibited that the MPEG-PLH-VES/B NPs accumulated at the tumor site more effectively than MPEG-PLH-VES NPs due to the biotin-mediated active targeting effect. In accordance with the in vitro results, DOX-loaded MPEG-PLH-VES/B NPs showed the strongest inhibitory effect against the MCF-7/ADR xenografted tumors with negligible systemic toxicity, as evidenced by the histological analysis and change of body weight. The multifunctional MPEG-PLH-VES/B nanoparticulate system has been demonstrated to provide a promising strategy for efficient delivery of DOX into MCF-7/ADR cancerous cells and reversing MDR.

Vibrating droplet generation to assemble zwitterion-coated gold-graphene oxide stealth nanovesicles for effective pancreatic cancer chemo-phototherapy

A vibrating nozzle approach was used to produce uniform (∼2 μm) hybrid droplets containing gold-graphene oxide (Au-GO), doxorubicin (DOX), and zwitterionic chitosan (ZC) for assembly of Au-GO@ZC-DOX stealth nanovesicles (NVs) via a single-pass diffusion drying process without any hydrothermal reactions, separations, or purifications. NVs were prepared with a lateral dimension of ∼53.0 nm, a pH-triggered high DOX release profile, and strong photothermal effects. Macrophage opsonization was prevented, resulting in anti-cancer and anti-migration effects, with high intracellular uptake in PANC-1 and MIA PaCa-2 cells. PANC-1 tumor uptake was greater for NVs having the ZC configuration than that for NVs without the ZC configuration, resulting in better anti-tumor effects with minimal toxicities. The vibrating nozzle approach offers significant potential to assemble multi-componential NVs for more efficient anti-tumor treatment and easy user-defined manufacturing of multifunctional nanomedicines.

Functional evaluation of doxorubicin decorated polymeric liposomal curcumin: a surface tailored therapeutic platform for combination chemotherapy

The present study deals with the hypothesis and design of new platform for the accommodation of curcumin and doxorubicin in surface engineered liposomes for combination chemotherapy.

The potential of multi-compound nanoparticles to bypass drug resistance in cancer

PURPOSE

The therapeutic efficacy of conventional chemotherapy against several solid tumors is generally limited and this is often due to the development of resistance or poor delivery of the drugs to the tumor. Mechanisms of resistance may vary between cancer types. However, with current development of genetic analyses, imaging, and novel delivery systems, we may be able to characterize and bypass resistance, e.g., by inhibition of the right target at the tumor site. Therefore, combined drug treatments, where one drug will revert or obstruct the development of resistance and the other will concurrently kill the cancer cell, are rational solutions. However, drug exposure of one drug will defer greatly from the other due to their physicochemical properties. In this sense, multi-compound nanoparticles are an excellent modality to equalize drug exposure, i.e., one common physicochemical profile. In this review, we will discuss novel approaches that employ nanoparticle technology that addresses specific mechanisms of resistance in cancer.

METHODS

The PubMed literature was consulted and reviewed.

RESULTS

Nanoparticle technology is emerging as a dexterous solution that may address several forms of resistance in cancer. For instance, we discuss advances that address mechanisms of resistance with multi-compound nanoparticles which co-deliver chemotherapeutics with an anti-resistance agent. Promising anti-resistance agents are (1) targeted in vivo gene silencing methods aimed to disrupt key resistance gene expression or (2) protein kinase inhibitors to disrupt key resistance pathways or (3) efflux pumps inhibitors to limit drug cellular efflux.

Recent advances in co-delivery systems based on polymeric nanoparticle for cancer treatment

Cancer is a broad term for a class of prevalent diseases as one in three people develop cancer during their lifetime. Although, there are few success stories of cancer therapy, most of the existing medications do not lead to complete recovery. Because of the complexity of cancer, usually a single therapeutic approach is insufficient for the suppression of cancer growth and metastasis. Simultaneous loading and co-delivery of different agents with different physiochemical characteristics to the same tumors have been suggested for minimizing the dose of anticancer drugs and achieving the synergistic therapeutic impacts in cancers treatment. Intense work to develop nanotechnology-based systems as a suitable option for cancer treatment is currently underway. The purpose of this review is to provide an overview of the co-delivery systems based on polymeric nanoparticles including polymeric micelles, dendrimers, poly-d,l-lactide-co-glycolide, polyethylenimine, poly(l-lysine) and chitosan for efficacious cancer therapy.

A review on the efficacy and toxicity of different doxorubicin nanoparticles for targeted therapy in metastatic breast cancer

In metastatic breast cancer (MBC), the conventional doxorubicin (DOX) has various problems due to lack of selectivity with subsequent therapeutic failure and adverse effects. DOX- induced cardiotoxicity is a major problem that necessitates the presence of new forms to decrease the risk of associated morbidity. Nanoparticles (NPs) are considered an important approach to selectively increase drug accumulation inside tumor cells and thus decreasing the associated side effects. Tumor cells develop resistance to chemotherapeutic agents through multiple mechanisms, one of which is over expression of efflux transporters. Various NPs have been investigated to overcome efflux mediated resistance. To date, only liposomal doxorubicin (LD) and pegylated liposomal doxorubicin (PLD) have entered phase II and III clinical trials and FDA- approved for clinical use in MBC. This review addresses the effects of LD and PLD on the hematological and palmar-plantar erythrodysesthesia (PPE) in anthracycline naïve and pretreated MBC patients. For evidence, studies to be included in this review were identified through PubMed, Cochrane and Google scholar databases. The results derived from: four phase III clinical trials that compared LD with the conventional DOX in naïve MBC patients, and ten non-comparative clinical trials investigated LD and PLD as monotherapy or combination in pretreated MBC. This work confirmed the cardiac tolerability profile of LD and PLD versus DOX, while hematological and skin toxicities were more common. Other DOX-NPs in preclinical trials were discussed in a chronological order. Finally, the modern preclinical development framework for DOX includes exosomal DOX (exo-DOX). Exosomal NPs are non-toxic, non-immunogenic, and can be engineered to have high cargo loading capacity and targeting specificity. These NPs have not been investigated clinically. Our study shows that the full clinical potentiality of DOX-NPs remains to be addressed to move the field forward.

Enhanced antitumor activity of epigallocatechin gallate–conjugated dual-drug-loaded polystyrene–polysoyaoil–diethanol amine nanoparticles for breast cancer therapy

The development of novel combination anticancer drug delivery systems is an important step to improve the effectiveness of anticancer treatment in metastatic breast cancer and to overcome increased toxicity of the currently used combination treatments. The aim of this study was to assess efficient targeting, therapeutic efficacy, and bioavailability of a combination of drugs (curcumin and α-tocopheryl succinate) loaded polystyrene–polysoyaoil–diethanol amine nanoparticles. Polystyrene–polysoyaoil–diethanol amine nanoparticles encapsulating two drugs, individually or in combination, were prepared by double-emulsion solvent evaporation method, resulting in particle size smaller than 250 nm with a surface negative charge between −30 and −40 mV. Entrapment efficiency of curcumin and α-tocopheryl succinate in the epigallocatechin gallate–conjugated dual-drug-loaded nanoparticles was found to be 68% and 80%, respectively. The release kinetics of curcumin and α-tocopheryl succinate from the nanoparticles exhibited a gradual and continuous profile followed by an initial burst behavior with a release over 20 days in vitro. Next, we have investigated the anticancer activity of nanoparticles encapsulating both the drugs and individually drug in human breast cancer cells (MDA-MB-231) using double-staining-based cell death analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assessment of cytotoxicity and flow cytometer. In vitro cytotoxicity studies revealed that epigallocatechin gallate–α-tocopheryl succinate/curcumin–polystyrene–polysoyaoil–diethanol amine nanoparticles are more potent than the corresponding α-tocopheryl succinate/curcumin–polystyrene–polysoyaoil–diethanol amine nanoparticles and their single-drug-loaded forms and show a synergistic and breast tumor targeting function. Thus, here, we propose epigallocatechin gallate–conjugated curcumin and α-tocopheryl succinate–loaded polystyrene–polysoyaoil–diethanol amine nanoparticles which effectively inhibit tumor growth and reduce toxicity compared to single-drug chemotherapy.

Athymic nude mice as an experimental model for cancer treatment

Athymic nude mice, a murine strain bearing spontaneous deletion in the Foxn1 gene that causes deteriorated or absent thymus (which results in inhibited immune system with reduction of number of T cells), represent a widely used model in cancer research having long lasting history as a tool for preclinical testing of drugs. The review describes three models of athymic mice that utilize cancer cell lines to induce tumors. In addition, various methods that can be applied in order to evaluate activity of anticancer agents in these models are shown and discussed. Although each model has certain disadvantages, they are still considered as inevitable instruments in many fields of cancer research, particularly in finding new drugs that would more effectively combat the cancer disease or enhance the use of current chemotherapy. Finally, the review summarizes strengths and weaknesses as well as future perspectives of the athymic nude mice model in cancer research.

Twist1 confers multidrug resistance in colon cancer through upregulation of ATP-binding cassette transporters

Multidrug resistance is a major problem in colon cancer treatment. However, its molecular mechanisms remain unclear. Recently, the epithelial-mesenchymal transition (EMT) in anticancer drug resistance has attracted increasing attention. This study investigated whether vincristine treatment induces EMT and promotes multidrug resistance in colon cancer. The result showed that vincristine treatment increases the expression of several ATP-binding cassette transporters in invasive human colon adenocarcinoma cell line (HCT-8). Vincristine-resistant HCT-8 cells (HCT-8/V) acquire a mesenchymal phenotype, and thus its migratory and invasive ability are increased both in vitro and in vivo. The master transcriptional factors of EMT, especially Twist1, were significantly increased in the HCT-8/V cell line. Moreover, the ectopic expression of Twist1 increased the chemoresistance of HCT-8 cells to vincristine and increased the expression levels and promoter activities of ABCB1 and ABCC1. Furthermore, Twist1 silencing reverses the EMT phenotype, enhances the chemosensitivity of HCT-8/ V cells to anticancer agents in vitro and in vivo, and downregulates the expression of ABCB1 and ABCC1. Twist1-mediated promotion of ABCB1 and ABCC1 expression levels plays an important role in the drug resistance of colon cancer cells.

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

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

Glutathione responsive polymers and their application in drug delivery systems

Materials which respond to biological cues are the subject of intense research interest due to their possible application in smart drug delivery vehicles.

Supramolecular cyclodextrin nanocarriers for chemo- and gene therapy towards the effective treatment of drug resistant cancers

A tumor active targeting β-cyclodextrin based nanocarrier β-NC-OEI-SS-FA was designed by the modification of star shaped cationic derivatives β-NC-OEI with folic acid through a disulfide bond, to co-deliver chemotherapeutic paclitaxel and the Nur77 gene for overcoming Bcl-2 mediated non-pump resistance by an "enemy to friend" strategy for potential drug resistant cancer therapy.

Biotin Decorated Gold Nanoparticles for Targeted Delivery of a Smart-Linked Anticancer Active Copper Complex: In Vitro and In Vivo Studies

The synthesis and anticancer activity of a copper(II) diacetyl-bis(N4-methylthiosemicarbazone) complex and its nanoconjugates are reported. The copper(II) complex is connected to a carboxylic acid group through a cleavable disulfide link to enable smart delivery. The copper complex is tethered to highly water-soluble 20 nm gold nanoparticles (AuNPs), stabilized by amine terminated lipoic acid-polyethylene glycol (PEG). The gold nanoparticle carrier was further decorated with biotin to achieve targeted action. The copper complex and the conjugates with and without biotin, were tested against HeLa and HaCaT cells. They show very good anticancer activity against HeLa cells, a cell line derived from cervical cancer and are less active against HaCaT cells. Slow and sustained release of the complex from conjugates is demonstrated through cleavage of disulfide linker in the presence of glutathione (GSH), a reducing agent intrinsically present in high concentrations within cancer cells. Biotin appended conjugates do not show greater activity than conjugates without biotin against HeLa cells. This is consistent with drug uptake studies, which suggests similar uptake profiles for both conjugates in vitro. However, in vivo studies using a HeLa cell xenograft tumor model shows 3.8-fold reduction in tumor volume for the biotin conjugated nanoparticle compared to the control whereas the conjugate without biotin shows only 2.3-fold reduction in the tumor volume suggesting significant targeting.

Selective Release of Hydrophobic and Hydrophilic Cargos from Multi-Stimuli-Responsive Nanogels

Highly stable multi-stimuli-responsive nanogels for selective release of simultaneously encapsulated hydrophobic and hydrophilic cargos in a spatiotemporally controlled manner are demonstrated here. The nanogel is composed of hydrophilic pH- and thermoresponsive poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and hydrophobic photocleavable o-nitrobenzyl (ONB) linkage. The hydrophobic cargos were noncovalently encapsulated into lipophilic interiors of the nanogels, while the hydrophilic cargos were chemically linked to the nanogel precursor polymer PDMAEMA through a redox-cleavable disulfide junction. For these dual-loaded nanogels, hydrophobic cargos can be released in response to temperature, pH, and UV light, while the hydrophilic cargos can be released in response to redox reagent. The stimuli-selective release of hydrophobic and hydrophilic cargos affords the system with great potential applications in combination chemotherapy, tissue engineering, anticorrosion, and smart nanoreactors.