Co-delivery of docetaxel and verapamil by reduction-sensitive PEG-PLGA-SS-DTX conjugate micelles to reverse the multi-drug resistance of breast cancer

Strategies, Challenges, and Prospects of Nanoparticles in Gynecological Malignancies

Gynecologic cancers are a significant health issue for women globally. Early detection and successful treatment of these tumors are crucial for the survival of female patients. Conventional therapies are often ineffective and harsh, particularly in advanced stages, necessitating the exploration of new therapy options. Nanotechnology offers a novel approach to biomedicine. A novel biosensor utilizing bionanotechnology can be employed for early tumor identification and therapy due to the distinctive physical and chemical characteristics of nanoparticles. Nanoparticles have been rapidly applied in the field of gynecologic malignancies, leading to significant advancements in recent years. This study highlights the significance of nanoparticles in treating gynecological cancers. It focuses on using nanoparticles for precise diagnosis and continuous monitoring of the disease, innovative imaging, and analytic methods, as well as multifunctional drug delivery systems and targeted therapies. This review examines several nanocarrier systems, such as dendrimers, liposomes, nanocapsules, and nanomicelles, for gynecological malignancies. The review also examines the enhanced therapeutic potential and targeted delivery of ligand-functionalized nanoformulations for gynecological cancers compared to nonfunctionalized anoformulations. In conclusion, the text also discusses the constraints and future exploration prospects of nanoparticles in chemotherapeutics. Nanotechnology will offer precise methods for diagnosing and treating gynecological cancers.

Enhanced Efficacy against Drug-Resistant Tumors Enabled by Redox-Responsive Mesoporous-Silica-Nanoparticle-Supported Lipid Bilayers as Targeted Delivery Vehicles

Multidrug resistance (MDR) is frequently induced after long-term exposure to reduce the therapeutic effect of chemotherapeutic drugs, which is always associated with the overexpression of efflux proteins, such as P-glycoprotein (P-gp). Nano-delivery technology can be used as an efficient strategy to overcome tumor MDR. In this study, mesoporous silica nanoparticles (MSNs) were synthesized and linked with a disulfide bond and then coated with lipid bilayers. The functionalized shell/core delivery systems (HT-LMSNs-SS@DOX) were developed by loading drugs inside the pores of MSNs and conjugating with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and hyaluronic acid (HA) on the outer lipid surface. HT-LMSNs-SS and other carriers were characterized and assessed in terms of various characteristics. HT-LMSNs-SS@DOX exhibited a dual pH/reduction responsive drug release. The results also showed that modified LMSNs had good dispersity, biocompatibility, and drug-loading capacity. In vitro experiment results demonstrated that HT-LMSNs-SS were internalized by cells and mainly by clathrin-mediated endocytosis, with higher uptake efficiency than other carriers. Furthermore, HT-LMSNs-SS@DOX could effectively inhibit the expression of P-gp, increase the apoptosis ratios of MCF-7/ADR cells, and arrest cell cycle at the G0/G1 phase, with enhanced ability to induce excessive reactive oxygen species (ROS) production in cells. In tumor-bearing model mice, HT-LMSNs-SS@DOX similarly exhibited the highest inhibition activity against tumor growth, with good biosafety, among all of the treatment groups. Therefore, the nano-delivery systems developed herein achieve enhanced efficacy towards resistant tumors through targeted delivery and redox-responsive drug release, with broad application prospects.

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.

Functionalized Lipid Nanocarriers for Simultaneous Delivery of Docetaxel and Tariquidar to Chemoresistant Cancer Cells

The simultaneous drug delivery efficiency of a co-loaded single-carrier system of docetaxel (DTX)- and tariquidar (TRQ)-loaded nanostructured lipid carrier (NLC) functionalized with PEG and RIPL peptide (PRN) (D^T-PRN) was compared with that of a physically mixed dual-carrier system of DTX-loaded PRN (D-PRN) and TRQ-loaded PRN (T-PRN) to overcome DTX mono-administration-induced multidrug resistance. NLC samples were prepared using the solvent emulsification evaporation technique and showed homogeneous spherical morphology, with nano-sized dispersion (<220 nm) and zeta potential values of −15 to −7 mV. DTX and/or TRQ was successfully encapsulated in NLC samples (>95% encapsulation efficiency and 73–78 µg/mg drug loading). In vitro cytotoxicity was concentration-dependent; D^T-PRN exhibited the highest MDR reversal efficiency, with the lowest combination index value, and increased the cytotoxicity and apoptosis in MCF7/ADR cells by inducing cell-cycle arrest in the G2/M phase. A competitive cellular uptake assay using fluorescent probes showed that, compared to the dual nanocarrier system, the single nanocarrier system exhibited better intracellular delivery efficiency of multiple probes to target cells. In the MCF7/ADR-xenografted mouse models, simultaneous DTX and TRQ delivery using D^T-PRN significantly suppressed tumor growth as compared to other treatments. A single co-loaded system for PRN-based co-delivery of DTX/TRQ (1:1, w/w) constitutes a promising therapeutic strategy for drug-resistant breast cancer cells.

Screening Multidrug Resistance Reversal Agents in Traditional Chinese Medicines by Efflux Kinetics of D-Luciferin in MCF-7/DOXFluc Cells

In this study, we established a simple and rapid in vitro method for screening multidrug resistance (MDR) reversal agents in traditional Chinese medicines (TCMs), which could better correspond to the MDR reversing effect in vivo. Here, D-luciferin, a substrate for the enzyme firefly luciferase and also a substrate for ATP-binding cassette transporters (ABC transporters), was used as the probe to detect its efflux kinetics caused by ABC transporters. First, we established a stable doxorubicin (DOX)-resistant cell line (MCF-7/DOX^Fluc) that overexpressed luciferase. Then, some kinds of TCMs were chosen for the MDR reversal agents to measure its effect on inhibiting the D-luciferin outflow from MCF-7/DOX^Fluc, and the ideal reversal agent with the least D-luciferin efflux from MCF-7/DOX^Fluc was selected to further investigate its effect combined with DOX on MCF-7/DOX^Fluc tumor-bearing mice. The results indicated that quercetin (Qu) could remarkably increase the retention of D-luciferin in MCF-7/DOX^Fluc in vitro and in vivo. Also, the combination of Qu and DOX could exceedingly inhibit the tumor growth, which proved the feasibility of this in vitro screening method. The study proposed a feasible method for mass screening of MDR agents from TCMs in vitro.

Synergistic co-administration of docetaxel and curcumin to chemoresistant cancer cells using PEGylated and RIPL peptide-conjugated nanostructured lipid carriers

Background

A targeted co-administration system of docetaxel (DTX) and curcumin (CUR) using a PEG-modified RIPL peptide (IPLVVPLRRRRRRRRC)-conjugated nanostructured lipid carrier (P/R-NLC) was constructed to exert synergistic anticancer effects against chemoresistant breast cancer.

Results

DTX- or CUR-loaded NLCs and P/R-NLCs were prepared using the solvent emulsification–evaporation method. NLCs showed homogeneous spherical morphology with nano-sized dispersion (< 210 nm) with zeta potential varying from − 16.4 to − 19.9 mV. DTX or CUR was successfully encapsulated in the NLCs: encapsulation efficiency (> 95%); drug loading (8 − 18%). All NLC formulations were stable for 4 weeks under the storage conditions at 4 °C. Drug release was diffusion-controlled, revealing the best fit to the Higuchi equation. DTX- or CUR-loaded formulations showed dose-dependent cytotoxicity. The DTX/CUR combination (1:3 w/w) in P/R-NLC formulations exhibited the strongest synergism in both MCF7 and MCF7/ADR cells with combination index values of 0.286 and 0.130, respectively. Co-treatment with DTX- or CUR-P/R-NLCs increased apoptosis in both cell lines exhibited the superior synergistic inhibitory effect on MCF7/ADR three-dimensional spheroids. Finally, in OVCAR3-xenografted mouse models, co-treatment with DTX- or CUR-loaded P/R-NLCs significantly suppressed tumor growth compared to the other treatment groups.

Conclusions

Co-administration of DTX/CUR (1:3 w/w) using P/R-NLCs induced a synergistic effect against chemoresistant cancer cells.

Graphical Abstract

nurP28, a New-to-Nature Zein-Derived Peptide, Enhances the Therapeutic Effect of Docetaxel in Breast Cancer Monolayers and Spheroids

The development of novel cancer therapeutic strategies has garnered increasing interest in cancer research. Among the therapeutic choices, chemosensitizers have shown exciting prospects. Peptides are an attractive alternative among the molecules that may be used as chemosensitizers. We rationally designed a new-to-nature peptide, nurP28, derived from the 22-kDa α-zein protein sequence (entry Q00919_MAIZE). The resultant sequence of the nurP28 peptide after the addition of arginine residues was LALLALLRLRRRATTAFIIP, and we added acetyl and amide groups at the N- and C-terminus, respectively, for capping. We evaluated the cytotoxicity of the nurP28 peptide alone and in combination with docetaxel in fibroblast monolayers and breast cancer monolayers and spheroids. Our results indicated that nurP28 is not cytotoxic to human fibroblasts or cancer cells. Nevertheless, when combined with 1 µM docetaxel, 3 ng/mL nurP28 induced equivalent (in MCF7 monolayers) and higher (in MCF7 spheroids) cytotoxic effects than 10-fold higher doses of docetaxel alone. These findings suggest that nurP28 may act as a chemosensitizer in breast cancer treatment. This study describes the enhancing “anti-cancer” effects of nurP28 in breast cancer 2D and 3D cultures treated with docetaxel. Further studies should explore the mechanisms underlying these effects and assess the clinical potential of our findings using animal models.

Smart design approaches for orally administered lipophilic prodrugs to promote lymphatic transport

Challenges to effective delivery of drugs following oral administration has attracted growing interest over recent decades. Small molecule drugs (<1000 Da) are generally absorbed across the gastrointestinal tract into the portal blood and further transported to the systemic circulation via the liver. This can result in a significant reduction to the oral bioavailability of drugs that are metabolically labile and ultimately lead to ineffective exposure and treatment. Targeting drug delivery to the intestinal lymphatics is attracting increased attention as an alternative route of drug transportation providing multiple benefits. These include bypassing hepatic first-pass metabolism and selectively targeting disease reservoirs residing within the lymphatic system. The particular physicochemical requirements for drugs to be able to access the lymphatics after oral delivery include high lipophilicity (logP>5) and high long-chain triglyceride solubility (> 50 mg/g), properties required to enable drug association with the lipoprotein transport pathway. The majority of small molecule drugs, however, are not this lipophilic and therefore not substantially transported via the intestinal lymph. This has contributed to a growing body of investigation into prodrug approaches to deliver drugs to the lymphatic system by chemical manipulation. Optimised lipophilic prodrugs have the potential to increase lymphatic transport thereby improving oral pharmacokinetics via a reduction in first pass metabolism and may also target of disease-specific reservoirs within the lymphatics. This may provide advantages for current pharmacotherapy approaches for a wide array of pathological conditions, e.g. immune disease, cancer and metabolic disease, and also presents a promising approach for advanced vaccination strategies. In this review, specific emphasis is placed on medicinal chemistry strategies that have been successfully employed to design lipophilic prodrugs to deliberately enable lymphatic transport. Recent progress and opportunities in medicinal chemistry and drug delivery that enable new platforms for efficacious and safe delivery of drugs are critically evaluated.

Emerging nanotechnology based combination therapies of taxanes for multiple drug-resistant cancers

'One drug- one target' to 'multiple drug- multiple targets' paradigm shifted to produce combination therapies, have found great outcomes to overcome multiple drug resistance (MDR). MDR is a significant barrier to the delivery of taxane-based anticancer medicines such as docetaxel, paclitaxel, and cabazitaxel. Due to MDR induced by drug efflux transporters, clinical application of these medications is impeded. To date, nanoformulations such as liposomes, micelles, polymeric nanoparticles, and gold nanoparticles have been investigated to deliver taxanes alone and in combination to reverse drug resistance. Despite the fact that various groups have already looked into taxane nano formulations in the literature, there isn't much in the way of polypharmacology and advanced nanoformulations with a focus on MDR. In this overview, we briefly covered the insights regarding MDR, difficulties related to current pharmaceutical products of taxanes, combination therapies of taxanes to combat MDR, all of which can be used to delve into cancer treatment.

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.

Therapeutic strategies to overcome taxane resistance in cancer

One of the primary causes of attenuated or loss of efficacy of cancer chemotherapy is the emergence of multidrug resistance (MDR). Numerous studies have been published regarding potential approaches to reverse resistance to taxanes, including paclitaxel (PTX) and docetaxel, which represent one of the most important classes of anticancer drugs. Since 1984, following the FDA approval of paclitaxel for the treatment of advanced ovarian carcinoma, taxanes have been extensively used as drugs that target tumor microtubules. Taxanes, have been shown to affect an array of oncogenic signaling pathways and have potent cytotoxic efficacy. However, the clinical success of these drugs has been restricted by the emergence of cancer cell resistance, primarily caused by the overexpression of MDR efflux transporters or by microtubule alterations. In vitro and in vivo studies indicate that the mechanisms underlying the resistance to PTX and docetaxel are primarily due to alterations in α-tubulin and β-tubulin. Moreover, resistance to PTX and docetaxel results from: 1) alterations in microtubule-protein interactions, including microtubule-associated protein 4, stathmin, centriole, cilia, spindle-associated protein, and kinesins; 2) alterations in the expression and activity of multidrug efflux transporters of the ABC superfamily including P-glycoprotein (P-gp/ABCB1); 3) overexpression of anti-apoptotic proteins or inhibition of apoptotic proteins and tumor-suppressor proteins, as well as 4) modulation of signal transduction pathways associated with the activity of several cytokines, chemokines and transcription factors. In this review, we discuss the abovementioned molecular mechanisms and their role in mediating cancer chemoresistance to PTX and docetaxel. We provide a detailed analysis of both in vitro and in vivo experimental data and describe the application of these findings to therapeutic practice. The current review also discusses the efficacy of different pharmacological modulations to achieve reversal of PTX resistance. The therapeutic roles of several novel compounds, as well as herbal formulations, are also discussed. Among them, many structural derivatives had efficacy against the MDR phenotype by either suppressing MDR or increasing the cytotoxic efficacy compared to the parental drugs, or both. Natural products functioning as MDR chemosensitizers offer novel treatment strategies in patients with chemoresistant cancers by attenuating MDR and increasing chemotherapy efficacy. We broadly discuss the roles of inhibitors of P-gp and other efflux pumps, in the reversal of PTX and docetaxel resistance in cancer cells and the significance of using a nanomedicine delivery system in this context. Thus, a better understanding of the molecular mechanisms mediating the reversal of drug resistance, combined with drug efficacy and the application of target-based inhibition or specific drug delivery, could signal a new era in modern medicine that would limit the pathological consequences of MDR in cancer patients.

Amlodipine and Verapamil, Voltage-Gated Ca2+ Channel Inhibitors, Suppressed the Growth of Gastric Cancer Stem Cells

BACKGROUND

The membrane transporters activated in cancer stem cells (CSCs) are the target of novel cancer therapies for gastric cancer. The present study investigated ion channel expression profiles in gastric CSCs (GCSCs).

METHODS

Cells strongly expressing CD44 were separated from MKN74 cells, a human gastric cancer cell line, by fluorescence-activated cell sorting (FACS), and GCSCs were identified based on tumorsphere formation. Gene expression profiles in GCSCs were examined by a microarray analysis.

RESULTS

Among MKN74 cells, CD44 messenger RNA levels were higher in CSCs than in non-CSCs. These CSCs also exhibited resistance to cisplatin. The microarray analysis revealed that the expression of several genes related to voltage-gated Ca²⁺ channels (VGCCs), including CACNA2D1 and CACNB4, was upregulated. The cytotoxicities of the CACNA2D1 inhibitor amlodipine and the CACNB4 inhibitor verapamil were greater at lower concentrations in CSCs than in non-CSCs, and markedly reduced tumorsphere numbers. Tumor volumes were significantly smaller in a xenograft nude mouse model treated with amlodipine or verapamil in combination with cisplatin than in that treated with cisplatin alone.

CONCLUSIONS

The present results indicate that VGCCs play a role in maintaining CSCs, and demonstrated the potential of their specific inhibitors, amlodipine and verapamil, as targeted therapeutic agents against gastric cancer.

Anti-CEA tagged iron nanoparticles for targeting triple-negative breast cancer

Systemic therapy is generally required for breast cancer. However, treatment toxicity and side effects are a concern, especially for triple-negative breast cancer (TNBC), a subtype that usually develops resistance to chemotherapy. To overcome this issue, new nanoformulations capable of targeting cancer cells have been developed and alternative biomarkers have been explored as target molecules for TNBC management. In this study, we performed an in vivo assay in a murine orthotopic TNBC model to evaluate the targeting ability of anti-carcinoembryonic antigen (anti-CEA) loaded nanoparticles (labelled MFCEA), which had been previously synthetized by our research group. 4T1 cells were injected in the mammary gland of balb-c mice, and tumors were evaluated for CEA expression by immunohistochemistry. Tumor-bearing mice received targeted (MFCEA) and non-targeted (MF) nanoparticles intraperitoneally. Tumors were removed 1, 4, 15 and 24h after treatment, and Prussian blue iron staining was performed. Our results showed, as far as we know for the first time, that 4T1 induced tumors are CEA positive, and this opens up new prospects for treating TNBC. Furthermore, MFCEA nanoparticles were able to target malignant tissue and were retained in the tumor for longer than MF nanoparticles. The retention property of MFCEA, together with the absence of toxicity observed in the MTT assay, make these nanoparticles a promising device for management of CEA positive tumors and perhaps for TNBC. Nevertheless, further studies must be carried out to improve their performance and ensure safety for clinical studies.

Co-delivery of gemcitabine prodrug along with anti NF-κB siRNA by tri-layer micelles can increase cytotoxicity, uptake and accumulation of the system in the cancers

Combination treatment based on gene and chemotherapy is a promising strategy for effective cancer treatment due to the limited therapeutic efficacy of anticancer drugs. Dual functional polymeric micelles (PMs) have been emerged as potent nanocarriers for combinational cancer therapy. In the present study, the potential of tri-layer PMs loaded with anti-nuclear factor-κB (NF-κB) siRNA and 4-(N)-stearoyl gemcitabine (GemC18) has been investigated for cancer treatment. PMs with different core hydrophobicity were prepared by using poly(ε-caprolactone), polyethyleneimine and polyethylene glycol (PCL-PEI-PEG) copolymers and evaluated. The results revealed that GemC18-loaded PMs were significantly more cytotoxic than free drug on breast and pancreatic cancer cells. However, the cytotoxicity of drug loaded micelles was decreased by increasing the micellar core hydrophobicity because of decreasing drug release rate. Moreover, siRNA loaded PMs could considerably inhibit NF-κB expression. PMs loaded with both GemC18 and siRNA exhibited higher capability to induce apoptosis and inhibit migration of both cells. PMs with the most hydrophobic core indicated higher tumor accumulation efficiency via in-vivo imaging study. In conclusion, the prepared PMs hold a promise as an attractive dual functional delivery system for an effective cancer therapy.

Tumor microenvironment-induced structure changing drug/gene delivery system for overcoming delivery-associated challenges

Nano-drug/gene delivery systems (DDS) are powerful weapons for the targeted delivery of various therapeutic molecules in treatment of tumors. Nano systems are being extensively investigated for drug and gene delivery applications because of their exceptional ability to protect the payload from degradation in vivo, prolong circulation of the nanoparticles (NPs), realize controlled release of the contents, reduce side effects, and enhance targeted delivery among others. However, the specific properties required for a DDS vary at different phase of the complex delivery process, and these requirements are often conflicting, including the surface charge, particle size, and stability of DDS, which severely reduces the efficiency of the drug/gene delivery. Therefore, researchers have attempted to fabricate structure, size, or charge changeable DDS by introducing various tumor microenvironment (TME) stimuli-responsive elements into the DDS to meet the varying requirements at different phases of the delivery process, thus improving drug/gene delivery efficiency. This paper summarizes the most recent developments in TME stimuli-responsive DDS and addresses the aforementioned challenges.

Construction and anti-tumor activities of disulfide-linked docetaxel-dihydroartemisinin nanoconjugates

Co-delivery of anti-tumor agents with outstanding stimulus-triggered drug release in tumor cells, especially with the aid of nanotechnology, provided the possibility to enhance delivery efficiency for targeting tumor cells and antitumor efficacy. In this paper, docetaxel-dihydroartemisinin nanoconjugates linked by disulfide bond were designed to increase co-delivery and anti-tumor efficacy. Docetaxel and dihydroartemisinin were synthesized using two-step reaction and furtherly assembled to nanoconjugates. Nanoprescription was optimized to evaluate its physicochemical properties. In vitro anti-tumor activities of nanoformulation were assessed by MTT. The flow cytometry was adopted to analyze cell apoptosis and cell cycle arrest. The wound healing assay was used to evaluate antimigratory-property. In vivo pharmacokinetic and pharmacodynamic studies were investigated in rats and 4T1 bearing Balb/c mice model after intravenous injection, respectively. The chemical structure of conjugate was confirmed. The prepared nanoparticles possessed uniform size distribution (172.10 ± 1.70 nm, PDI 0.05 ± 0.01), was stable during storage period, sustained release profiles and sensitive reduction responsiveness. MTT assay indicated that the toxicity of nanoconjugates was slightly weak. Flow cytometry studies showed that nanoconjugates could promote early apoptosis significantly and mainly arose from G₀/G₁ phase. The wound healing assay provided an obvious antimetastatic potential of nanoparticles in 4T1 cells. The result of pharmacokinetic study suggested that nanoconjugates exhibited higher exposure levels. In vivo pharmacodynamic research showed that mice treated with docetaxel-dihydroartemisinin nanoconjugates had lower systemic toxicity and higher survival ratio than those of control groups. This potential of nanoconjugates was developed as a novel nanoplateform to treat tumor.

Muscone/RI7217 co-modified upward messenger DTX liposomes enhanced permeability of blood-brain barrier and targeting glioma

Rationale: The dual-targeted drug delivery system was designed for enhancing permeation of the blood-brain barrier (BBB) and providing an anti-glioma effect. As transferrin receptor (TfR) is over-expressed by the brain capillary endothelial (hCMEC/D3) and glioma cells, a mouse monoclonal antibody, RI7217, with high affinity and selectivity for TfR, was used to study the brain targeted drug delivery system. Muscone, an ingredient of traditional Chinese medicine (TCM) musk, was used as the "guide" drug to probe the permeability of the BBB for drug delivery into the cerebrospinal fluid. This study investigated the combined effects of TCM aromatic resuscitation and modern receptor-targeted technology by the use of muscone/RI7217 co-modified docetaxel (DTX) liposomes for enhanced drug delivery to the brain for anti-glioma effect. Methods: Cellular drug uptake from the formulations was determined using fluorescence microscopy and flow cytometry. The drug penetrating ability into tumor spheroids were visualized using confocal laser scanning microscopy (CLSM). In vivo glioma-targeting ability of formulations was evaluated using whole-body fluorescent imaging system. The survival curve study was performed to evaluate the anti-glioma effect of the formulations. Results: The results showed that muscone and RI7217 co-modified DTX liposomes enhanced uptake into both hCMEC/D3 and U87-MG cells, increased penetration to the deep region of U87-MG tumor spheroids, improved brain targeting in vivo and prolonged survival time of nude mice bearing tumor. Conclusion: Muscone and RI7217 co-modified DTX liposomes were found to show improved brain targeting and enhanced the efficacy of anti-glioma drug treatment in vivo.

Pluronic micelles with suppressing doxorubicin efflux and detoxification for efficiently reversing breast cancer resistance

The antitumor activity of doxorubicin (DOX) is often limited owing to the occurrence of multidrug resistance (MDR) during treatment. Herein, we developed hybrid polymeric micelles, which consisted of pluronic F127 as long-circulating helper in blood, and phenylboronic ester-grafted pluronic P123 (PHE) as efflux and detoxification regulator to efficiently deliver DOX and reverse MDR in vivo. Hybrid F127/PHE micelles exhibited higher stability and drug encapsulation (~80%) than simple F127/P123 micelles due to its lower CMC, and displayed in vitro drug release in a hydrogen peroxide (H₂O₂)-sensitive manner. Besides, DOX-loaded hybrid micelles (F127/PHE-DOX) possessed higher cell-killing ability and induce more apoptotic in MDR-cells than other groups, which was probably because it not only could greatly increase intracellular drug concentration by inhibiting P-gp mediated drug efflux, but also promote reactive oxygen species (ROS) generation by decreasing glutathione (GSH) levels. Besides, in vivo evaluation indicated that F127/PHE-DOX could well accumulate at tumor regions and exhibit the strongest tumor growth inhibition (TGI 87.87%) accompanied with low side effects. As a result, F127/PHE micelles had great potentials as a platform for anticancer drugs delivery and tumor MDR reversal in clinical application.

Dual-responsive TPGS crosslinked nanocarriers to overcome multidrug resistance

Efficient delivery of chemotherapeutic agents into tumor cells and reversal of chemoresistance are crucially important to enhance cancer therapy.

Nanotargeted agents: an emerging therapeutic strategy for breast cancer

Breast cancer is the most common female cancer worldwide and represents 12% of all cancer cases. Improvements in survival rates are largely attributed to improved screening and diagnosis. Conventional chemotherapy remains an important treatment option but it is beset with poor cell selectivity, serious side effects and resistance. Nanoparticle drug delivery systems bring promising opportunities to breast cancer treatment. They may improve chemotherapy by targeting drugs to tumors, generating high drug concentrations at tumors providing slow release of the drug, increased drug stability and concomitant reductions in side effects. The nanotechnology-based drug delivery approaches and the current research and application status of nano-targeted agents for breast cancer are discussed in this review to provide a basis for further study on targeted drug delivery systems.

Co-Delivery Nanosystems for Cancer Treatment: A Review

Massive data available on cancer therapy more than ever lead our mind to the general concept that there is no perfect treatment for cancer. Indeed, the biological complexity of this disease is too excessive to be treated by a single therapeutic approach. Current delivery systems containing a specific drug or gene have their particular opportunities and restrictions. It is worth noting that a considerable number of studies suggest that single- drug delivery systems result in insufficient suppression of cancer growth. Therefore, one of the main ideas of co-delivery system designing is to enhance the intended response or to achieve the synergistic/combined effect compared to the single drug strategy. This review focuses on various strategies for co-delivery of therapeutic agents in the treatment of cancer. The primary approaches within the script are categorized into co-delivery of conventional chemotherapeutics, gene-based molecules, and plant-derived materials. Each one is explained in examples with the recent researches. In the end, a brief summary is provided to conclude the gist of the review.

A novel smart PEGylated gelatin nanoparticle for co-delivery of doxorubicin and betanin: A strategy for enhancing the therapeutic efficacy of chemotherapy

Betanin (BET) can reduce the side effects of potent anticancer drugs e.g. doxorubicin (DOX) on the normal tissues in co-administration with them because of the synergistic therapeutic effect and consequently the reduced required amount of anticancer agents. Despite interest in the use of BET, incomplete oral absorption and low stability of BET limit its application. Thus, in this study to overcome the restrictions of BET and providing the synergistic effect of DOX@BET, we designed a new pH-responsive nanocarrier via decoration of gelatin nanoparticles (GNPs) by (methoxy poly (ethylene glycol)-poly ((2-dimethylamino) ethyl methacrylate-co-itaconic acid) (PGNPs). DOX and BET were effectively loaded (the loading capacity of 20.5% and 16.25%, respectively) into the PGNPs and this nanoplatform exhibited the suitable small particle size (162 nm). Additionally, the triggered release ability of drugs was studied through the assessment of simulated physiological and tumor tissue environments and showed the controlled release of DOX and BET with adjusting the pH of environment. Moreover, the synergistic effect of DOX@BET loaded PGNPs decreased the cell viability amount of breast cancer cells (MCF-7) respect to the free form of DOX or BET which indicated that the developed smart nanocarrier will be a hopeful nanocarrier for cancer therapy.

Rational Design of IR820- and Ce6-Based Versatile Micelle for Single NIR Laser-Induced Imaging and Dual-Modal Phototherapy

Phototherapy as a promising cancer diagnostic and therapeutic strategy has aroused extensive attention. However, single-wavelength near-infrared (NIR) light-triggered combinational treatment of photothermal therapy (PTT) and photodynamic therapy (PDT) is still a great challenge. Herein, a multifunctional micelle activated by a single-wavelength laser for simultaneous PTT and PDT as well as fluorescence imaging is developed. Briefly, new indocyanine green (IR820) is conjugated to d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) via the linker 6-aminocaproic acid, and then, chlorin e6 (Ce6) is encapsulated into the micelles formed by TPGS-IR820 conjugates to fabricate TPGS-IR820/Ce6 micelles. As the well-designed TPGS-IR820 conjugate shares a similar peak absorption wavelength with Ce6, this micelle can be applied with a single NIR laser (660 nm). The stable micelles exhibit excellent photothermal conversion efficiency in vitro and in vivo as well as high singlet oxygen generation capacity in tumor cells. After efficient cellular internalization, the as-prepared micelles display outstanding anticancer activity upon single NIR laser irradiation in vitro and in vivo. Furthermore, TPGS-IR820/Ce6 micelles show negligible systemic toxicity. The highly safe and effective TPGS-IR820/Ce6 micelles can offer an innovative strategy to construct single NIR light-induced PTT and PDT combined phototherapy nanoplatforms via suitable modification of organic phototherapeutic agents.

pH-Sensitive Poly(β-amino ester)s Nanocarriers Facilitate the Inhibition of Drug Resistance in Breast Cancer Cells

Multidrug resistance (MDR) remains an unmet challenge in chemotherapy. Stimuli-responsive nanocarriers emerge as a promising tool to overcome MDR. Herein, pH-sensitive poly(β-amino ester)s polymers (PHP)-based micellar nanoparticles were synthesized for enhanced doxorubicin (DOX) delivery in drug resistant breast cancer MCF-7/ADR cells. DOX-loaded PHP micelles showed rapid cell-internalization and lysosomal escape in MCF-7/ADR cells. The cytotoxicity assays showed relatively higher cell inhibition of DOX-loaded PHP micelles than that of free DOX against MCF-7/ADR cells. Further mechanistic studies showed that PHP micelles were able to inhibit P-glycoprotein (P-gp) activity by lowering mitochondrial membrane potentials and ATP levels. These results suggested that the enhanced antitumor effect might be attributed to PHP-mediated lysosomal escape and drug efflux inhibition. Therefore, PHP would be a promising pH-responsive nanocarrier for enhanced intracellular drug delivery and overcoming MDR in cancer cells.

A journey from the endothelium to the tumor tissue: distinct behavior between PEO-PCL micelles and polymersomes nanocarriers

Polymeric nanocarriers must overcome several biological barriers to reach the vicinity of solid tumors and deliver their encapsulated drug. This study assessed the in vitro and in vivo passage through the blood vessel wall to tumors of two well-characterized polymeric nanocarriers: poly(ethyleneglycol-b-ε-caprolactone) micelles and polymersomes charged with a fluorescent membrane dye (DiO: 3,3'-dioctadecyloxacarbo-cyanine perchlorate). The internalization and translocation from endothelial (human primary endothelial cells HUVEC) to cancer cells (human tumor cell line HCT-116) was studied in conventional 2D monolayers, 3D tumor spheroids, or in an endothelium model based on transwell assay. Micelles induced a faster DiO internalization compared to polymersomes but the latter crossed the endothelial monolayer more easily. Both translocation rates were enhanced by the addition of a pro-inflammatory factor or in the presence of tumor cells. These results were confirmed by early in vivo experiments. Overall, this study pointed out the room for the improvement of polymeric nanocarriers design to avoid drug losses when crossing the blood vessel walls.

VE-Albumin Core-Shell Nanoparticles for Paclitaxel Delivery to Treat MDR Breast Cancer

Multi-drug resistance (MDR) presents a serious problem in cancer chemotherapy. In this study, Vitamin E (VE)-Albumin core-shell nanoparticles were developed for paclitaxel (PTX) delivery to improve the chemotherapy efficacy in an MDR breast cancer model. The PTX-loaded VE-Albumin core-shell nanoparticles (PTX-VE NPs) had small particle sizes (about 100 nm), high drug entrapment efficiency (95.7%) and loading capacity (12.5%), and showed sustained release profiles, in vitro. Docking studies indicated that the hydrophobic interaction and hydrogen bonds play a significant role in the formation of the PTX-VE NPs. The results of confocal laser scanning microscopy analysis demonstrated that the cell uptake of PTX was significantly increased by the PTX-VE NPs, compared with the NPs without VE (PTX NPs). The PTX-VE NPs also exhibited stronger cytotoxicity, compared with PTX NPs with an increased accumulation of PTX in the MCF-7/ADR cells. Importantly, the PTX-VE NPs showed a higher anti-cancer efficacy in MCF-7/ADR tumor xenograft model than the PTX NPs and the PTX solutions. Overall, the VE-Albumin core-shell nanoparticles could be a promising nanocarrier for PTX delivery to improve the chemotherapeutic efficacy of MDR cancer.

Thiol redox-sensitive cationic polymers for dual delivery of drug and gene

Recently greater emphasis has been given to combination therapy for generating synergistic effects of treating cancer. Recent studies on thiol-sensitive nanocarriers for the delivery of drug or gene have shown promising results. In this review, we will examine the rationale and advantage in using nanocarriers for the combined delivery of different anticancer drugs and biologics. Here, we also discuss the role of nanocarriers, particularly redox-sensitive polymers in evading or inhibiting the efflux pump in cancer and how they modulate the sensitivity of cancer cells. The review aims to provide a good understanding of the new pattern of cancer treatment and key concerns for designing nanomedicine of synergistic combinations for cancer therapy.

Evaluation of Anti-Tumor Efficacy of Vorinostat Encapsulated Self-Assembled Polymeric Micelles in Solid Tumors

Vorinostat (VOR), a potent HDAC inhibitor, suffers from low solubility and poor absorption, which hinders its successful application in therapy, especially in the treatment of solid tumors. In this study, an effort to improve the physicochemical characteristics of VOR was made by encapsulating it in PEG-PLGA copolymeric micelles. VOR-loaded PEG-PLGA micelles (VOR-PEG-PLGA) were produced by thin-film hydration and physicochemically characterized. The PEG-PLGA micelles had an average size of 124.06 ± 2.6 nm, polydispersity index of 0.27 ± 0.1, and entrapment efficiency of 90 ± 2.1%. Micelles were characterized by TEM, DSC, and drug release studies. The drug release occurred in a sustained manner up to 72 h from PEG-PLGA micelles. In the in vitro cell-based studies using human breast cancer (MDA MB 231) and murine melanoma (B16F10) cell lines, VOR-PEG-PLGA micelles exhibited superior cellular internalization, enhanced cytotoxic activity, and greater apoptosis compared to free drug. Percent cell killing of 54.9% for VOR-PEG-PLGA-treated cells was observed after 24 h compared to 36% for free VOR in MDA MB 231 cell line. Further, significant tumor suppression was witnessed in B16F10 tumor-bearing mice treated with VOR-PEG-PLGA micelles with a 1.78-fold reduction in tumor volume compared to free VOR-treated animals. Overall, the VOR-PEG-PLGA micelles improved the biopharmaceutical properties of VOR, which resulted in enhanced anti-tumor efficacy. Therefore, the newly developed nano-formulation of VOR could be considered as an effective treatment option in solid tumors.

Polymeric micelles for potentiated antiulcer and anticancer activities of naringin

Naringin is one of the most interesting phytopharmaceuticals that has been widely investigated for various biological actions. Yet, its low water solubility, limited permeability, and suboptimal bioavailability limited its use. Therefore, in this study, polymeric micelles of naringin based on pluronic F68 (PF68) were developed, fully characterized, and optimized. The optimized formula was investigated regarding in vitro release, storage stability, and in vitro cytotoxicity vs different cell lines. Also, cytoprotection against ethanol-induced ulcer in rats and antitumor activity against Ehrlich ascites carcinoma in mice were investigated. Nanoscopic and nearly spherical 1:50 micelles with the mean diameter of 74.80±6.56 nm and narrow size distribution were obtained. These micelles showed the highest entrapment efficiency (EE%; 96.14±2.29). The micelles exhibited prolonged release up to 48 vs 10 h for free naringin. The stability of micelles was confirmed by insignificant changes in drug entrapment, particle size, and retention (%) (91.99±3.24). At lower dose than free naringin, effective cytoprotection of 1:50 micelles against ethanol-induced ulcer in rat model has been indicated by significant reduction in mucosal damage, gastric level of malondialdehyde, gastric expression of tumor necrosis factor-alpha, caspase-3, nuclear factor kappa-light-chain-enhancer of activated B cells, and interleukin-6 with the elevation of gastric reduced glutathione and superoxide dismutase when compared with the positive control group. As well, these micelles provoked pronounced antitumor activity assessed by potentiated in vitro cytotoxicity particularly against colorectal carcinoma cells and tumor growth inhibition when compared with free naringin. In conclusion, 1:50 naringin-PF68 micelles can be represented as a potential stable nanodrug delivery system with prolonged release and enhanced antiulcer as well as antitumor activities.

Rational Design of an Amphiphilic Chlorambucil Prodrug Realizing Self-Assembled Micelles for Efficient Anticancer Therapy

The application of anticancer drug chlorambucil (CLB) in chemotherapy is severely restricted by its insolubility, lability, and toxic side effects; therefore, it is challenging to realize a highly efficient anticancer therapy of chlorambucil. To solve the above drawbacks encountered by chlorambucil, herein we proposed an amphiphilic chlorambucil prodrug-based self-assembled micelle strategy to realize the highly efficient anticancer therapy of chlorambucil. 1,6-Hexanediamine hydrochloride (HDH) serving as the hydrophilic segment was covalently bound to hydrophobic CLB to prepare an amphiphilic prodrug CLB-HDH which could self-assemble into micelles in aqueous solution. These micelles can passively target tumor tissues via the enhanced permeability and retention (EPR) effect, leading to enhanced cellular internalization. Both the cytotoxicity assay in vitro and anticancer study in vivo confirmed the excellent therapeutic activity of CLB-HDH micelles in comparison with free chlorambucil. Moreover, the hemolysis examination and histological analysis demonstrated the designed CLB-HDH micelles are safe in drug delivery. Therefore, our designed amphiphilic prodrug CLB-HDH micelles bring new opportunity for chlorambucil clinical application to combat cancers.

Redox-Responsive Core-Cross-Linked Block Copolymer Micelles for Overcoming Multidrug Resistance in Cancer Cells

Success of chemotherapy as a treatment for cancer has been often inhibited by multidrug resistance (MDR) of the cancer cells. There is a clear need to generate strategies to overcome this resistance. In this work, we have developed redox-responsive and core-cross-linked micellar nanocarriers using poly(ethylene glycol)-block-poly(2-(methacryloyloxy)ethyl 5-(1,2-dithiolan-3-yl)pentanoate) diblock copolymers (PEG-b-PLAHEMA) with tunable swelling properties for the delivery of drugs toward drug-sensitive MDA-MB-231 and drug-resistant MDA-MB-231 (231R) cancer cells. PEG-b-PLAHEMA containing varying number of 2-(methacryloyloxy)ethyl 5-(1,2-dithiolan-3-yl)pentanoate (LAHEMA) units were synthesized by employing the reversible addition-fragmentation chain transfer polymerization technique. The block copolymer self-assembly, cross-linking induced by reduction, and de-cross-linking triggered time-dependent controlled swelling of micelles were studied using dynamic light scattering, fluorescence spectroscopy, and transmission electron microscopy. In vitro cytotoxicity, cellular uptake efficiency, and glutathione-responsive anticancer activity of doxorubicin (DOX) encapsulated in core-cross-linked block copolymer micelles (CCMs) toward both drug-sensitive and drug-resistant cancer cell lines were evaluated. Significant reduction in IC₅₀ was observed by DOX-loaded CCMs toward drug-resistant 231R cancer cell lines, which was further improved by coencapsulating DOX and verapamil (a P-glycoprotein inhibitor) in CCMs. Thus, these reduction-sensitive biocompatible CCMs with tunable swelling property are very promising in overcoming MDR in cancer cells.

Redox-responsive F127-folate/F127-disulfide bond-d-α-tocopheryl polyethylene glycol 1000 succinate/P123 mixed micelles loaded with paclitaxel for the reversal of multidrug resistance in tumors

Introduction

The development of nanodrug carriers utilizing tumor microenvironment has become a hotspot in reversing multidrug resistance (MDR).

Materials and methods

This study synthesized a redox-sensitive copolymer, Pluronic F127-disulfide bond-d-α-tocopheryl polyethylene glycol 1000 succinate (FSST), through the connection of the reduction-sensitive disulfide bond between F127 and d-α-tocopheryl polyethylene glycol 1000 succinate. This polymer could induce the elevation of reactive oxygen species (ROS) levels, ultimately resulting in cytotoxicity. Moreover, the redox-responsive mixed micelles, F127-folate (FA)/FSST/P123 (FFSSTP), based on FSST, Pluronic F127-FA, and Pluronic P123, were prepared to load paclitaxel (PTX).

Results

The in vitro release study demonstrated that FFSSTP/PTX accelerated the PTX release through the breakage of disulfide bond in reductive environment. In cellular experiment, FFSSTP/PTX induced significant apoptosis in PTX-resistant MCF-7/PTX cells through inhibiting adenosine triphosphate (ATP)-binding cassette proteins from pumping out PTX by interfering with the mitochondrial function and ATP synthesis. Furthermore, FFSSTP/PTX induced apoptosis through elevating the intracellular levels of ROS.

Conclusion

FFSSTP could become a potential carrier for the treatment of MDR tumors.

Disulfide bond based polymeric drug carriers for cancer chemotherapy and relevant redox environments in mammals

Increasing numbers of disulfide linkage-employing polymeric drug carriers that utilize the reversible peculiarity of this unique covalent bond have been reported. The reduction-sensitive disulfide bond is usually employed as a linkage between hydrophilic and hydrophobic polymers, polymers and drugs, or as cross-linkers in polymeric drug carriers. These polymeric drug carriers are designed to exploit the significant redox potential difference between the reducing intracellular environments and relatively oxidizing extracellular spaces. In addition, these drug carriers can release a considerable amount of anticancer drug in response to the reducing environment when they reach tumor tissues, effectively improving antitumor efficacy. This review focuses on various disulfide linkage-employing polymeric drug carriers. Important redox thiol pools, including GSH/GSSG, Cys/CySS, and Trx1, as well as redox environments in mammals, will be introduced.