Overcoming multidrug resistance by co-delivery of Mdr-1 and survivin-targeting RNA with reduction-responsible cationic poly(β-amino esters)

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Overcoming Chemotherapy Resistance in Metastatic Cancer: A Comprehensive Review

The management of metastatic cancer is complicated by chemotherapy resistance. This manuscript provides a comprehensive academic review of strategies to overcome chemotherapy resistance in metastatic cancer. The manuscript presents background information on chemotherapy resistance in metastatic cancer cells, highlighting its clinical significance and the current challenges associated with using chemotherapy to treat metastatic cancer. The manuscript delves into the molecular mechanisms underlying chemotherapy resistance in subsequent sections. It discusses the genetic alterations, mutations, and epigenetic modifications that contribute to the development of resistance. Additionally, the role of altered drug metabolism and efflux mechanisms, as well as the activation of survival pathways and evasion of cell death, are explored in detail. The strategies to overcome chemotherapy resistance are thoroughly examined, covering various approaches that have shown promise. These include combination therapy approaches, targeted therapies, immunotherapeutic strategies, and the repurposing of existing drugs. Each strategy is discussed in terms of its rationale and potential effectiveness. Strategies for early detection and monitoring of chemotherapy drug resistance, rational drug design vis-a-vis personalized medicine approaches, the role of predictive biomarkers in guiding treatment decisions, and the importance of lifestyle modifications and supportive therapies in improving treatment outcomes are discussed. Lastly, the manuscript outlines the clinical implications of the discussed strategies. It provides insights into ongoing clinical trials and emerging therapies that address chemotherapy resistance in metastatic cancer cells. The manuscript also explores the challenges and opportunities in translating laboratory findings into clinical practice and identifies potential future directions and novel therapeutic avenues. This comprehensive review provides a detailed analysis of strategies to overcome chemotherapy resistance in metastatic cancer. It emphasizes the importance of understanding the molecular mechanisms underlying resistance and presents a range of approaches for addressing this critical issue in treating metastatic cancer.

Umbilical Cord Blood-Derived M1 Macrophage Exosomes Loaded with Cisplatin Target Ovarian Cancer In Vivo and Reverse Cisplatin Resistance

We investigated the therapeutic efficacy of umbilical cord blood (UCB)-derived M1 macrophage exosomes loaded with cisplatin (CIS) in ovarian cancer and platinum resistance. M1 macrophages were purified by using CD14 magnetic beads and characterized by flow cytometry. Our analyses included morphology, particle size, particle concentration, potential, drug loading capacity, counts of entry into cells, antitumor effect in vivo, and the ability to reverse drug resistance. A2780, SKOV3, and A2780/DDP, SKOV3/DDP ovarian cancer cells (CIS-sensitive and CIS-resistant cell lines, respectively) were treated with CIS or CIS-loaded M1 macrophage exosomes (M1exoCISs). The encapsulation efficiency of CIS loading into M1 macrophage exosomes was approximately 30%. In vitro, M1exoCIS treatment reduced the CIS IC50 values of both A2780, SKOV3, and A2780/DDP, SKOV3/DDP cells. We evaluated the effect of M1exoCIS on tumor growth using a mouse ovarian cancer subcutaneous transplantation tumor model inoculated with A2780/DDP cells. M1exoCIS was observed in the liver, spleen, and tumor sites 24 h posttreatment; the fluorescence intensity of M1exoCIS is higher than that of CIS. After 7 days, M1exoCIS significantly inhibited the growth of subcutaneously transplanted tumors compared with CIS alone and had a longer survival time. Moreover, the toxicity test shows that M1exoCIS has less hepatorenal toxicity than CIS. To investigate the mechanism of M1exoCIS targeting, homing, and reversing drug resistance, we performed RT-PCR, Western blotting, and Proteome Profiler Human Receptor Array analyses. We found that A2780 and A2780/DDP cells expressed the integrin β1/CD29 receptor, while M1 exosomes expressed integrin β1/CD29. In addition, M1exos carries long noncoding RNA H19, implicated in PTEN protein upregulation and miR-130a and Pgp gene downregulation, leading to the reversal of CIS drug resistance. Therefore, UCB-derived M1exoCIS target tumor sites of ovarian cancer in vivo and can be used to increase the CIS sensitivity and cytotoxicity.

Antibacterial and pH-sensitive methacrylate poly-L-Arginine/poly (β-amino ester) polymer for soft tissue engineering

During the last decade, pH-sensitive biomaterials containing antibacterial agents have grown exponentially in soft tissue engineering. The aim of this study is to synthesize a biodegradable pH sensitive and antibacterial hydrogel with adjustable mechanical and physical properties for soft tissue engineering. This biodegradable copolymer hydrogel was made of Poly-L-Arginine methacrylate (Poly-L-ArgMA) and different poly (β- amino ester) (PβAE) polymers. PβAE was prepared with four different diacrylate/diamine monomers including; 1.1:1 (PβAE1), 1.5:1 (PβAE1.5), 2:1 (PβAE2), and 3:1 (PβAE3), which was UV cross-linked using dimethoxy phenyl-acetophenone agent. These PβAE were then used for preparation of Poly-L-ArgMA/PβAE polymers and revealed a tunable swelling ratio, depending on the pH conditions. Noticeably, the swelling ratio increased by 1.5 times when the pH decreased from 7.4 to 5.6 in the Poly-L-ArgMA/PβAE1.5 sample. Also, the controllable degradation rate and different mechanical properties were obtained, depending on the PβAE monomer ratio. Noticeably, the tensile strength of the PβAE hydrogel increased from 0.10 ± 0.04 MPa to 2.42 ± 0.3 MPa, when the acrylate/diamine monomer molar ratio increased from 1.1:1 to 3:1. In addition, Poly-L-ArgMA/PβAE samples significantly improved L929 cell viability, attachment and proliferation. Poly-L-ArgMA also enhanced the antibacterial activities of PβAE against both Escherichia coli (~5.1 times) and Staphylococcus aureus (~2.7 times). In summary, the antibacterial and pH-sensitive Poly-L-ArgMA/PβAE1.5 with suitable mechanical, degradation and biological properties could be an appropriate candidate for soft tissue engineering, specifically wound healing applications.

Recent advances in anti-multidrug resistance for nano-drug delivery system

Chemotherapy for tumors occasionally results in drug resistance, which is the major reason for the treatment failure. Higher drug doses could improve the therapeutic effect, but higher toxicity limits the further treatment. For overcoming drug resistance, functional nano-drug delivery system (NDDS) has been explored to sensitize the anticancer drugs and decrease its side effects, which are applied in combating multidrug resistance (MDR) via a variety of mechanisms including bypassing drug efflux, controlling drug release, and disturbing metabolism. This review starts with a brief report on the major MDR causes. Furthermore, we searched the papers from NDDS and introduced the recent advances in sensitizing the chemotherapeutic drugs against MDR tumors. Finally, we concluded that the NDDS was based on several mechanisms, and we looked forward to the future in this field.

Combination of polythyleneimine regulating autophagy prodrug and Mdr1 siRNA for tumor multidrug resistance

Multidrug resistance (MDR) has been restricting the efficacy of chemotherapy, which mainly include pump resistance and non-pump resistance. In order to fight overall MDR, a novel targeted gene/drug co-deliver nano system is developed, which can suppress the drug efflux pumps and modulate autophagy to overcoming both pump and non-pump resistance. Here, small interfere RNA (siRNA) is incorporated into polymer-drug conjugates (PEI-PTX, PP) which are composed of polyethyleneimine (PEI) and paclitaxel (PTX) via covalent bonds, and hyaluronic acid (HA) is coated on the surface of PP/siRNA to achieve long blood cycle and CD44-targeted delivery. The RNA interference to mdr1 gene is combined with autophagy inhibition by PP, which efficiently facilitate apoptosis of Taxol-resistant lung cancer cells (A549/T). Further study indicates that PEI in PP may play a significant role to block the autophagosome–lysosome fusion process by means of alkalizing lysosomes. Both in vitro and in vivo studies confirm that the nanoassemblies can successfully deliver PTX and siRNA into tumor cells and significantly inhibited A549/T tumor growth. In summary, the polymeric nanoassemblies provide a potential strategy for combating both pump and non-pump resistance via the synergism of RNAi and autophagy modulation.

CD44/Folate Dual Targeting Receptor Reductive Response PLGA-Based Micelles for Cancer Therapy

In this study, a novel poly (lactic-co-glycolic acid) (PLGA)-based micelle was synthesized, which could improve the therapeutic effect of the antitumor drug doxorubicin hydrochloride (DOX) and reduce its toxic and side effects. The efficient delivery of DOX was achieved by active targeting mediated by double receptors and stimulating the reduction potential in tumor cells. FA-HA-SS-PLGA polymer was synthesized by amidation reaction, and then DOX-loaded micelles were prepared by dialysis method. The corresponding surface method was used to optimize the experimental design. DOX/FA-HA-SS-PLGA micelles with high drug loading rate and encapsulation efficiency were prepared. The results of hydrophilic experiment, critical micelle concentration determination, and hemolysis test all showed that DOX/FA-HA-SS-PLGA micelles had good physicochemical properties and biocompatibility. In addition, both in vitro reduction stimulus response experiment and in vitro release experiment showed that DOX/FA-HA-SS-PLGA micelles had reduction sensitivity. Molecular docking experiments showed that it can bind to the target protein. More importantly, in vitro cytology studies, human breast cancer cells (MCF-7), human non-small cell lung cancer cells (A549), and mouse colon cancer cells (CT26) were used to demonstrate that the dual receptor-mediated endocytosis pathway resulted in stronger cytotoxicity to tumor cells and more significant apoptosis. In and in vivo antitumor experiment, tumor-bearing nude mice were used to further confirm that the micelles with double targeting ligands had better antitumor effect and lower toxicity. These experimental results showed that DOX/FA-HA-SS-PLGA micelles have the potential to be used as chemotherapeutic drugs for precise tumor treatment.

Opportunities in combinational chemo-immunotherapy for breast cancer using nanotechnology: an emerging landscape

INTRODUCTION

Breast carcinoma (BC) is one of the most frequent causes of cancer-related death among women, which is due to the poor response to conventional therapy. There are several complications associated with monotherapy for cancer, such as cytotoxicity to normal cells, multidrug resistance (MDR), side effects, and limited applications. To overcome these challenges, a combination of chemotherapy and immunotherapy (monoclonal antibodies, anticancer vaccines, checkpoint inhibitors, and cytokines) has been introduced. Drug delivery systems (DDSs) based on nanotechnology have more applications in BC treatment owing to their controlled and targeted drug release with lower toxicity and reduced adverse drug effects. Several nanocarriers, such as liposomes, nanoparticles, dendrimers, and micelles, have been used for the effective delivery of drugs.

AREAS COVERED

This article presents opportunities and challenges in BC treatment, the rationale for cancer immunotherapy, and several combinational approaches with their applications for BC treatment.

EXPERT OPINION

Nanotechnology can be used for the early prognosis and cure of BC. Several novel and targeted DDSs have been developed to enhance the efficacy of anticancer drugs. This article aims to understand new strategies for the treatment of BC and the appropriate design of nanocarriers used as a combinational DDS.

Current understandings and clinical translation of nanomedicines for breast cancer therapy

Breast cancer is one of the most frequently diagnosed cancers that is threatening women's life. Current clinical treatment regimens for breast cancer often involve neoadjuvant and adjuvant systemic therapies, which somewhat are associated with unfavorable features. Also, the heterogeneous nature of breast cancers requires precision medicine that cannot be fulfilled by a single type of systemically administered drug. Taking advantage of the nanocarriers, nanomedicines emerge as promising therapeutic agents for breast cancer that could resolve the defects of drugs and achieve precise drug delivery to almost all sites of primary and metastatic breast tumors (e.g. tumor vasculature, tumor stroma components, breast cancer cells, and some immune cells). Seven nanomedicines as represented by Doxil® have been approved for breast cancer clinical treatment so far. More nanomedicines including both non-targeting and active targeting nanomedicines are being evaluated in the clinical trials. However, we have to realize that the translation of nanomedicines, particularly the active targeting nanomedicines is not as successful as people have expected. This review provides a comprehensive landscape of the nanomedicines for breast cancer treatment, from laboratory investigations to clinical applications. We also highlight the key advances in the understanding of the biological fate and the targeting strategies of breast cancer nanomedicine and the implications to clinical translation.

Recent advancements and future submissions of silica core-shell nanoparticles

The core-shell silica-based nanoparticles (CSNPs) possess outstanding properties for developing next-generation therapeutics. CSNPs provide greater surface area owing to their mesoporous structure, which offers a high opportunity for surface modification. This review highlights the potential of core-shell silica-based nanoparticle (CSNP) based injectable nanotherapeutics (INT); its role in drug delivery, biomedical imaging, light-triggered phototherapy, Plasmonic enhancers, gene delivery, magnetic hyperthermia, immunotherapy, and potential as next-generation theragnostic. Specifically, the conceptual crosstalk on modern synthetic strategies, biodistribution profiles with a mechanistic view on the therapeutics loading and release modeling are dealt in detail. The manuscript also converses the challenges associated with CSNPs, regulatory hurdles, and their current market position.

Treating Autoimmune Inflammatory Diseases with an siERN1-Nanoprodrug That Mediates Macrophage Polarization and Blocks Toll-like Receptor Signaling

The clinical application of small interfering RNA (siRNA) drugs provides promising opportunities to develop treatment strategies for autoimmune inflammatory diseases. In this study, siRNAs targeting the endoplasmic reticulum to nucleus signaling 1 (ERN1) gene (siERN1) were screened. Two cationic polymers, polyethylenimine (PEI) and poly(β-amino amine) (PBAA), which can improve the efficiency of the siRNA transfection, were used as siERN1 delivery carriers. They were implemented to construct a nanodrug delivery system with macrophage-targeting ability and dual responsiveness for the treatment of autoimmune inflammatory diseases. In terms of the mechanism, siERN1 can regulate the intracellular calcium ion concentration by interfering with the function of inositol 1,4,5-trisphosphate receptor 1/3 (IP3R1/3) and thus inducing M2 polarization of macrophages. Furthermore, siERN1-nanoprodrug [FA (folic acid)-PEG-R(RKKRRQRRR)-NPs(ss-PBAA-PEI)@siERN1] acts as a conductor of macrophage polarization by controlling the calcium ion concentration and is an inhibitor of MyD88-dependent Toll-like receptor signaling. The results revealed that the FA-PEG-R-NPs@siERN1 has universal biocompatibility, long-term drug release responsiveness, superior targeting properties, and therapeutic effects in mouse collagen-induced arthritis and inflammatory bowel disease models. In conclusion, this study reveals a potential strategy to treat autoimmune inflammatory disorders.

Smart stimuli-responsive nanocarriers for the cancer therapy – nanomedicine

Nanomedicine is ongoing current research in the applications of nanotechnology for cancer therapy. Simply from a technology perspective, this field of research has an enormous broadening and success to date. Recently, nanomedicine has also made inroads in the treatment of cancer. Stimuli-responsive nanoparticles are an emerging field of research because its targeting capacity is of great interest in the treatment of cancer. The responsive nanoparticles are efficient in encountering different internal biological stimuli (acidic, pH, redox, and enzyme) and external stimuli (temperature, ultrasounds, magnetic field, and light), which are used as smart nanocarriers for delivery of the chemotherapeutic and imaging agents for cancer therapy. In-depth, the responsive nanocarrier that responds to the biological cues is of pronounced interest due to its capability to provide a controlled release profile at the tumor-specific site. The outlook of this review focuses on the stimuli-responsive nanocarrier drug delivery systems in sequence to address the biological challenges that need to be evaluated to overcome conventional cancer therapy.

Recent advances in co-delivery nanosystems for synergistic action in cancer treatment

Nanocarrier delivery systems have been widely studied to carry unique or dual chemical drugs. The major challenge of chemotherapies is to overcome the multidrug-resistance (MDR) of cells to antineoplastic medicines. In this context, nano-scale technology has allowed researchers to develop biocompatible nano-delivery systems to overcome the limitation of chemical agents. The development of nano-vehicles may also be directed to co-deliver different agents such as drugs and genetic materials. The delivery of nucleic acids targeting specific cells is based on gene therapy principles to replace the defective gene, correct genome errors or knock-down a particular gene. Co-delivery systems are attractive strategies due to the possibility of achieving synergistic therapeutic effects, which are more effective in overcoming the MDR of cancer cells. These combined therapies can provide better outcomes than separate delivery approaches carrying either siRNA, miRNA, pDNA, or drugs. This article reviews the main design features that need to be associated with nano-vehicles to co-deliver drugs, genes, and gene-drug combinations with efficacy. The advantages and disadvantages of co-administration approaches are also overviewed and compared with individual nanocarrier systems. Herein, future trends and perspectives in designing novel nano-scale platforms to co-deliver therapeutic agents are also discussed.

Multifunctional nanoplatforms co-delivering combinatorial dual-drug for eliminating cancer multidrug resistance

Clinically, the primary cause of chemotherapy failure belongs to the occurrence of cancer multidrug resistance (MDR), which directly leads to the recurrence and metastasis of cancer along with high mortality. More and more attention has been paid to multifunctional nanoplatform-based dual-therapeutic combination to eliminate resistant cancers. In addition to helping both cargoes improve hydrophobicity and pharmacokinetic properties, increase bioavailability, release on demand and enhance therapeutic efficacy with low toxic effects, these smart co-delivery nanocarriers can even overcome drug resistance. Here, this review will not only present different types of co-delivery nanocarriers, but also summarize targeted and stimuli-responsive combination nanomedicines. Furthermore, we will focus on the recent progress in the co-delivery of dual-drug using such intelligent nanocarriers for surmounting cancer MDR. Whereas it remains to be seriously considered that there are some knotty issues in the fight against MDR of cancers via using co-delivery nanoplatforms, including limited intratumoral retention, the possible changes of combinatorial ratio under complex biological environments, drug release sequence from the nanocarriers, and subsequent free-drug resistance after detachment from the nanocarriers. It is hoped that, with the advantage of continuously developing nanomaterials, two personalized therapeutic agents in combination can be better exploited to achieve the goal of cooperatively combating cancer MDR, thus advancing the time to clinical transformation.

Survivin silencing improved the cytotoxicity of carboplatin and melphalan in Y79 and primary retinoblastoma cells

Survivin stands out as one of the most specific cancer targets discovered to date. Although single inhibition, e.g. through small interfering RNA (siRNA), has shown modest results in clinical trials, its combination with drugs holds promise to sensitize cancer cells to chemotherapeutics. In this study, we propose a sequential treatment of siRNA survivin followed by chemotherapy. Firstly, we demonstrated that siRNA-loaded switchable lipid nanoparticles (siLNP) silence survivin in a panel of cancer cell lines. Subsequently, we selected retinoblastoma (RB) as our model to screen four chemotherapeutic agents: carboplatin, topotecan, melphalan or teniposide. The effect of drugs on survivin expression and caspase-3 was investigated by RT-qPCR. The best drug combination was selected measuring the viability, survivin expression and the selectivity of the treatment. Our stepwise method revealed that siRNA delivery by switchable LNP sensitized Y79, but not the healthy APRE-19 cell line, to carboplatin and melphalan cytotoxicity. This ability was validated on primary human RB cells. Finally, the distinct behavior of the drugs demonstrated that a diligent screening of drugs should be envisioned when looking for synergy with survivin. Our sequential approach highlighted carboplatin and melphalan as agents to be investigated in future survivin-associated in vivo testing to tackle RB.

Design and Fabrication of Dual Redox Responsive Nanoparticles with Diselenide Linkage Combined Photodynamically to Effectively Enhance Gene Expression

BACKGROUND

PEI is currently the most used non-viral gene carrier and the transfection efficiency is closely related to the molecular weight; however, the prominent problem is that the cytotoxicity increased with the molecular weight.

METHODS

A novel redox responsive biodegradable diselenide cross-linked polymer (dPSP) was designed to enhance gene expression. ICG-pEGFP-TRAIL/dPSP nanoparticles with high drug loading are prepared, which have redox sensitivity and plasmid protection. The transfection efficiency of dPSP nanoparticle was evaluated in vitro.

RESULTS

The plasmid was compressed by 100% at the N/P ratio of 16, and the particle size was less than 100 nm. When explored onto high concentrations of GSH/H2O2, dPSP4 degraded into small molecular weight cationic substances with low cytotoxicity rapidly. Singlet oxygen (1O2) was produced when indocyanine green (ICG) was irradiated by near-infrared laser irradiation (NIR) to promote oxidative degradation of dPSP4 nanoparticles. Under the stimulation of NIR 808 and redox agent, the particle size and PDI of ICG-pDNA/dPSP nanoparticle increased significantly.

CONCLUSION

Compared with gene therapy alone, co-transportation of dPSP4 nanoparticle with ICG and pEGFP-TRAIL had better antitumor effect. Diselenide-crosslinked polyspermine had a promising prospect on gene delivery and preparation of multifunctional anti-tumor carrier.

Photosensitizer-Doped and Plasma Membrane-Responsive Liposomes for Nuclear Drug Delivery and Multidrug Resistance Reversal

Clinically approved doxorubicin (Dox)-loaded liposomes (e.g., Doxil) guarantee good biosafety, but their insufficient nuclear delivery of Dox (<0.4%) after cellular uptake significantly hampers their final anticancer efficacy. Here, we report that simply doping protoporphyrin IX (PpIX, a commonly used hydrophobic photosensitizer) into the lipid bilayers of Dox-loaded liposomes (the resultant product is termed PpIX/Dox liposomes) is a feasible way to promote the nuclear delivery of Dox. This facile strategy relies on a unique property of PpIX-it presents considerably higher affinity for the real plasma membrane over its liposomal carrier, which drives the doped PpIX molecules to detach from the liposomes when encountering cancer cells. We demonstrate that this process can trigger the efficient release of the loaded Dox molecules and allow them to enter the nuclei of MCF-7 breast cancer cells without being trapped by lysosomes. Regarding the drug-resistant MCF-7/ADR cells, the aberrant activation of the efflux pumps in the plasma membranes expels the internalized Dox. However, we strikingly find that the robust drug resistance can be reversed upon mild laser irradiation because the photodynamic effect of PpIX disrupts the drug efflux system (e.g., P-glycoprotein) and facilitates the nuclear entry of Dox. As a proof-of-concept, this PpIX doping strategy is also applicable for enhancing the effectiveness of cisplatin-loaded liposomes against both A549 and A549/DDP lung cancer cells. In vivo experimental results prove that a single injection of PpIX/Dox liposomes completely impedes the growth of MCF-7 tumors in nude mice within 2 weeks and, in combination with laser irradiation, can synergistically ablate MCF-7/ADR tumors. Biosafety assessments reveal no significant systemic toxicity caused by PpIX/Dox liposomes. This work exemplifies a facile method to modulate the subcellular fate of liposomal drugs and may inspire the optimization of nanopharmaceuticals in the near future.

Cancer-Targeting Nanoparticles for Combinatorial Nucleic Acid Delivery

Nucleic acids are a promising type of therapeutic for the treatment of a wide range of conditions, including cancer, but they also pose many delivery challenges. For efficient and safe delivery to cancer cells, nucleic acids must generally be packaged into a vehicle, such as a nanoparticle, that will allow them to be taken up by the target cells and then released in the appropriate cellular compartment to function. As with other types of therapeutics, delivery vehicles for nucleic acids must also be designed to avoid unwanted side effects; thus, the ability of such carriers to target their cargo to cancer cells is crucial. Classes of nucleic acids, hurdles that must be overcome for effective intracellular delivery, types of nonviral nanomaterials used as delivery vehicles, and the different strategies that can be employed to target nucleic acid delivery specifically to tumor cells are discussed. Additonally, nanoparticle designs that facilitate multiplexed delivery of combinations of nucleic acids are reviewed.

Dual-functionalized liposome by co-delivery of paclitaxel with sorafenib for synergistic antitumor efficacy and reversion of multidrug resistance

Multidrug resistance (MDR) remains one of the major reasons for inefficiency of many chemotherapeutic agents in cancer therapy. In this study, a D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) and polylysine-deoxycholic acid copolymer (PLL-DA) co-modified cationic liposome coating with hyaluronic acid (HA) was constructed for co-delivery of paclitaxel (PTX) and chemosensitizing agent, sorafenib (SOR) to treat the MDR cancer. The multifunctional liposome (HA-TPD-CL-PTX/SOR) presented good stability against rat plasma and was capable of reversing surface zeta potential under acidic conditions in the presence of HAase. Additionally, experimental result confirmed that the PLL-DA copolymer would facilitate the endo-lysosomal escape of the liposome. In vitro study demonstrated that HA-TPD-CL-PTX/SOR could significantly enhance drug accumulation in resistant MCF-7/MDR cells by inhibiting the P-gp efflux, and effectively inhibited growth of tumor cells. Furthermore, the liposome showed an enhanced anticancer activity in vivo, with a tumor growth inhibition rate of 78.52%. In summary, HA-TPD-CL-PTX/SOR exhibited a great potential for effective therapy of resistant cancers by combining with chemotherapeutic agents and could be a promising nano-carrier for reversing MDR and improving the effectiveness of chemotherapy.

Polyamidoamine dendrimers-based nanomedicine for combination therapy with siRNA and chemotherapeutics to overcome multidrug resistance

Multidrug resistance (MDR) significantly decreases the therapeutic efficiency of anti-cancer drugs. Its reversal could serve as a potential method to restore the chemotherapeutic efficiency. Downregulation of MDR-related proteins with a small interfering RNA (siRNA) is a promising way to reverse the MDR effect. Additionally, delivery of small molecule therapeutics simultaneously with siRNA can enhance the efficiency of chemotherapy by dual action in MDR cell lines. Here, we conjugated the dendrimer, generation 4 polyamidoamine (G4 PAMAM), with a polyethylene glycol (PEG)-phospholipid copolymer. The amphiphilic conjugates obtained spontaneously self-assembled into a micellar nano-preparation, which can be co-loaded with siRNA onto PAMAM moieties and sparingly water-soluble chemotherapeutics into the lipid hydrophobic core. This system was co-loaded with doxorubicin (DOX) and therapeutic siRNA (siMDR-1) and tested for cytotoxicity against MDR cancer cells: human ovarian carcinoma (A2780 ADR) and breast cancer (MCF7 ADR). The combination nanopreparation effectively downregulated P-gp in MDR cancer cells and reversed the resistance towards DOX.

Poly(β-Amino Esters): Synthesis, Formulations, and Their Biomedical Applications

Poly(β-amino ester) (abbreviated as PBAE or PAE) refers to a polymer synthesized from an acrylate and an amine by Michael addition and has properties inherent to tertiary amines and esters, such as pH responsiveness and biodegradability. The versatility of building blocks provides a library of polymers with miscellaneous physicochemical and mechanical properties. When used alone or together with other materials, PBAEs can be fabricated into different formulations in order to fulfill various requirements in drug delivery (for instance, gene, anticancer drugs, and antimicrobials delivery) and natural complex mimicry (nanochaperones). This progress report discusses the recent developments in design, synthesis, formulations, and applications of PBAEs in biomedical fields and provides a perspective view for the future of the PBAEs.

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.

Reduction-sensitive polymeric nanomedicines: An emerging multifunctional platform for targeted cancer therapy

The development of smart delivery systems that are robust in circulation and quickly release drugs following selective internalization into target cancer cells is a key to precision cancer therapy. Interestingly, reduction-sensitive polymeric nanomedicines showing high plasma stability and triggered cytoplasmic drug release behavior have recently emerged as one of the most exciting platforms for targeted delivery of various anticancer drugs including small chemical drugs, proteins, and nucleic acids. In vivo studies in varying tumor models reveal that these reduction-sensitive multifunctional nanomedicines outperform the currently used clinical formulations and reduction-insensitive counterparts, bringing about not only significantly enhanced tumor selectivity, accumulation and inhibition efficacy but also markedly reduced systemic toxicity and improved therapeutic index. In this review, we will highlight the cutting-edge advancement with a focus on in vivo performances as well as future perspectives on reduction-sensitive polymeric nanomedicines for targeted cancer therapy.

Enhancing the therapeutic effect via elimination of hepatocellular carcinoma stem cells using Bmi1 siRNA delivered by cationic cisplatin nanocapsules

Resistance of hepatocellular carcinoma (HCC) to systemic chemotherapy is partially due to presence of drug-resistant cancer stem cells. Bmi1 protein is essential for survival and proliferation of HCC cancer stem cells (CSCs). Here, we report that Bmi1 siRNA (Bmi1siR) loaded in cationic nanocapsules of cisplatin (NPC) eliminated stem cells in situ HCC in mice. NPC/Bmi1siR was fabricated via electrostatic complexation of Bmi1 siRNA to NPCs, which had cores composed of cisplatin and were coated with cationic lipids. In vivo, NPC/Bmi1siR showed higher anti-tumor activity in HCC bearing mice compared with cisplatin or NPC. Critically, both flow cytometry (FACS) analysis in vitro and histological examination in vivo revealed that side population or CD133+ HCC cells were dramatically decreased by NPC/Bmi1siR treatment, suggesting that HCC CSCs were eliminated. Altogether, our results suggest that drug resistance of HCC can be overcome by co-delivering Bmi1 siRNA with cisplatin in cationic nanocapsules.

Dishevelled1-3 contribute to multidrug resistance in colorectal cancer via activating Wnt/β-catenin signaling

Multidrug resistance is a great obstacle in successful chemotherapy of colorectal cancer. However, the molecular mechanism underlying multidrug resistance is not fully understood. Dishevelled, a pivot in Wnt signaling, has been linked to cancer progression, while its role in chemoresistance remains unclear. Here, we found that Dishevelled1-3 was over-expressed in multidrug-resistant colorectal cancer cells (HCT-8/VCR) compared to their parental cells. Silencing Dishevelled1-3 resensitized HCT-8/VCR cells to multiple drugs including vincristine, 5-fluorouracil and oxaliplatin. Moreover, Dishevelled1-3 increased the protein levels of multidrug resistance protein 1 (P-gp/MDR1), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP), Survivin and Bcl-2 which are correlated with multidrug resistance. shβ-catenin abolished Dishevelled-mediated these protein expressions. Unexpectedly, none of Dishevelled1-3 controlled β-catenin accumulation and nuclear translocation. Furthermore, the nuclear translocations of Dishevelled1-3 were promoted in HCT-8/VCR cells compared to HCT-8. Dishevelled1-3 bound to β-catenin in nucleus, and promoted nuclear complex formation and transcription activity of β-catenin/TCF. Taken together, Dishevelled1-3 contributed to multidrug resistance in colorectal cancer via activating Wnt/β-catenin signaling and inducing the expressions of P-gp, MRP2, BCRP, Survivin and Bcl-2, independently of β-catenin accumulation and nuclear translocation. Silencing Dishevelled1-3 resensitized multidrug-resistant colorectal cancer cells, providing a novel therapeutic target for successful chemotherapy of colorectal cancer.

Nanotechnology-based combination therapy for overcoming multidrug-resistant cancer

Multidrug resistance (MDR) is a major obstacle to successful cancer treatment and is crucial to cancer metastasis and relapse. Combination therapy is an effective strategy for overcoming MDR. However, the different pharmacokinetic (PK) profiles of combined drugs often undermine the combination effect in vivo, especially when greatly different physicochemical properties (e.g., those of macromolecules and small drugs) combine. To address this issue, nanotechnology-based codelivery techniques have been actively explored. They possess great advantages for tumor targeting, controlled drug release, and identical drug PK profiles. Thus, a powerful tool for combination therapy is provided, and the translation from in vitro to in vivo is facilitated. In this review, we present a summary of various combination strategies for overcoming MDR and the nanotechnology-based combination therapy.

Systematic evaluation of multifunctional paclitaxel-loaded polymeric mixed micelles as a potential anticancer remedy to overcome multidrug resistance

Multidrug resistance (MDR) of tumor cells is becoming the main reason for the failure of chemotherapy and P-glycoprotein (P-gp) mediated drug efflux has demonstrated to be the key factor for MDR. To address this issue, a novel pH-responsive mixed micelles drug delivery system composed of dextran-g-poly(lactide-co-glycolide)-g-histidine (HDP) and folate acid-D-α-tocopheryl polyethylene glycol 2000 (FA-TPGS2K) copolymers has been designed for the delivery of antitumor agent, paclitaxel (PTX) via FA-receptor mediated cell endocytosis, into PTX-resistant breast cancer MCF-7 cells (MCF-7/PTX). PTX-loaded FA-TPGS2K/HDP mixed micelles were characterized to have a small size distribution, high loading content and excellent pH-responsive drug release profiles. Compared with HDP micelles, FA-TPGS2K/HDP mixed micelles showed a higher cytotoxicity against MCF-7 and MCF-7/PTX cells due to the synergistic effect of FA-receptor mediated cell endocytosis, pH-responsive drug release and TPGS mediated P-gp inhibition. P-gp expression level, ATP content and mitochondrial membrane potential change have been measured, the results indicated blank FA-TPGS2K/HDP mixed micelles could inhibit the P-gp activity by reducing the mitochondrial membrane potential and depleting ATP content but not down-regulating the P-gp expression. In vivo antitumor activities demonstrated FA-TPGS2K/HDP mixed micelles could reach higher antitumor activity compared with HDP micelles for MCF-7/PTX tumor cells. Histological assay also indicated that FA-TPGS2K/HDP mixed micelles showed strongly apoptosis inducing effect, anti-proliferation effect and anti-angiogenesis effect. All these evidences demonstrated this pH-sensitive FA-TPGS2K/HDP micelle-based drug delivery system is a promising approach for overcoming MDR.

STATEMENT OF SIGNIFICANCE

In this work, a novel FA-TPGS2K copolymer has been synthesized and used it to construct mixed micelles with HDP copolymer to overcome MDR effect. Furthermore, a series in vitro and in vivo evaluations have been made, which supported enough evidences for the efficient delivery of antitumor drug to MDR cells.

Inhibition of breast cancer metastasis by paclitaxel-loaded pH responsive poly(β-amino ester) copolymer micelles

Aim: Tumor metastasis is one of the leading causes of insufficient chemotherapy during cancer treatment. In this study, a poly(β-amino ester) derivate was developed to fabricate paclitaxel (PTX) entrapped pH-responsive copolymer micelles for inhibition of breast cancer metastasis. Materials & methods: PTX-loaded micelles were fabricated by thin film hydration method. The inhibition efficacy of the as-prepared micelles was evaluated on MDA-MB-231 cells and tumor bearing mice. Results: PTX-loaded micelles were successfully prepared. Such micelles could promote drug uptake and MDA-MB-231 cell deaths, and suppress tumor metastasis. Conclusion: The pH-responsive PTX-loaded micelles are promising candidates in developing stimuli triggered drug delivery systems in acidic tumor microenvironments with improved inhibitory effects on tumor metastasis.

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

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

A RNA nanotechnology platform for a simultaneous two-in-one siRNA delivery and its application in synergistic RNAi therapy

Incorporating multiple copies of two RNAi molecules into a single nanostructure in a precisely controlled manner can provide an efficient delivery tool to regulate multiple gene pathways in the relation of mutual dependence. Here, we show a RNA nanotechnology platform for a two-in-one RNAi delivery system to contain polymeric two RNAi molecules within the same RNA nanoparticles, without the aid of polyelectrolyte condensation reagents. As our RNA nanoparticles lead to the simultaneous silencing of two targeted mRNAs, of which biological functions are highly interdependent, combination therapy for multi-drug resistance cancer cells, which was studied as a specific application of our two-in-one RNAi delivery system, demonstrates the efficient synergistic effects for cancer therapy. Therefore, this RNA nanoparticles approach has an efficient tool for a simultaneous co-delivery of RNAi molecules in the RNAi-based biomedical applications, and our current studies present an efficient strategy to overcome multi-drug resistance caused by malfunction of genes in chemotherapy.

Chemistry of Mesoporous Organosilica in Nanotechnology: Molecularly Organic-Inorganic Hybridization into Frameworks

Organic-inorganic hybrid materials aiming to combine the individual advantages of organic and inorganic components while overcoming their intrinsic drawbacks have shown great potential for future applications in broad fields. In particular, the integration of functional organic fragments into the framework of mesoporous silica to fabricate mesoporous organosilica materials has attracted great attention in the scientific community for decades. The development of such mesoporous organosilica materials has shifted from bulk materials to nanosized mesoporous organosilica nanoparticles (designated as MONs, in comparison with traditional mesoporous silica nanoparticles (MSNs)) and corresponding applications in nanoscience and nanotechnology. In this comprehensive review, the state-of-art progress of this important hybrid nanomaterial family is summarized, focusing on the structure/composition-performance relationship of MONs of well-defined morphology, nanostructure, and nanoparticulate dimension. The synthetic strategies and the corresponding mechanisms for the design and construction of MONs with varied morphologies, compositions, nanostructures, and functionalities are overviewed initially. Then, the following part specifically concentrates on their broad spectrum of applications in nanotechnology, mainly in nanomedicine, nanocatalysis, and nanofabrication. Finally, some critical issues, presenting challenges and the future development of MONs regarding the rational synthesis and applications in nanotechnology are summarized and discussed. It is highly expected that such a unique molecularly organic-inorganic nanohybrid family will find practical applications in nanotechnology, and promote the advances of this discipline regarding hybrid chemistry and materials.

An overview of the effective combination therapies for the treatment of breast cancer

Breast cancer (BC) is generally classified based on the receptors overexpressed on the cell nucleus, which include hormone receptors such as progesterone (PR) and estrogen (ER), and HER2. Triple-negative breast cancer (TNBC) is a type of cancer that lacks any of these three types of receptor proteins (ER/PR/HER2). Tumor cells exhibit drug resistant phenotypes that decrease the efficacy of chemotherapeutic treatments. Generally, drug resistance has a genetic basis that is caused by an abnormal gene expression, nevertheless, there are several types of drug resistance: efflux pumps reducing the cellular concentration of the drug, alterations in membrane lipids that reduce cellular uptake, increased or altered drug targets, metabolic alteration of the drug, inhibition of apoptosis, repair of the damaged DNA, and alteration of the cell cycle checkpoints. The use of "combination therapy" is recognized as an efficient solution to treat human diseases, in particular, breast cancer. In this review, we give examples of different nanocarriers used to co-deliver multiple therapeutics (chemotherapeutic agent and nucleic acid) to drug-resistant tumor cells, and lastly, we give our recommendations for the future directions for the co-delivery treatments.

Large Pore-Sized Hollow Mesoporous Organosilica for Redox-Responsive Gene Delivery and Synergistic Cancer Chemotherapy

A stability-difference-selective bond-breakage strategy for the fabrication of largepore-sized hollow mesoporous organosilica nanoparticles (HMONs) is successfully developed. Moreover, surfacefunctionalized HMONs are successfully constructed to simultaneously deliver P-gp modulator siRNA and anticancer drug doxorubicin to reverse the multidrug resistance of cancer cells.

Knockdown of SALL4 inhibits the proliferation and reverses the resistance of MCF-7/ADR cells to doxorubicin hydrochloride

Background

Breast cancer is the most frequent malignancy in women and drug resistance is the major obstacle for its successful chemotherapy. In the present study, we analyzed the involvement of an oncofetal gene, sal-like 4 (SALL4), in the tumor proliferation and drug resistance of human breast cancer.

Results

Our study showed that SALL4 was up-regulated in the drug resistant breast cancer cell line, MCF-7/ADR, compared to the other five cell lines. We established the lentiviral system expressing short hairpin RNA to knockdown SALL4 in MCF-7/ADR cells. Down-regulation of SALL4 inhibited the proliferation of MCF-7/ADR cells and induced the G1 phase arrest in cell cycle, accompanied by an obvious reduction of the expression of cyclinD1 and CDK4. Besides, down-regulating SALL4 can re-sensitize MCF-7/ADR to doxorubicin hydrochloride (ADMh) and had potent synergy with ADMh in MCF-7/ADR cells. Depletion of SALL4 led to a decrease in IC50 for ADMh and an inhibitory effect on the ability to form colonies in MCF-7/ADR cells. With SALL4 knockdown, ADMh accumulation rate of MCF-7/ADR cells was increased, while the expression of BCRP and c-myc was significantly decreased. Furthermore, silencing SALL4 also suppressed the growth of the xenograft tumors and reversed their resistance to ADMh in vivo.

Conclusion

SALL4 knockdown inhibits the growth of the drug resistant breast cancer due to cell cycle arrest and reverses tumor chemo-resistance through down-regulating the membrane transporter, BCPR. Thus, SALL4 has potential as a novel target for the treatment of breast cancer.

Co-delivery of drugs and plasmid DNA for cancer therapy

Cancer is an extremely complex disease involving multiple signaling pathways that enable tumor cells to evade programmed cell death, thus making cancer treatment extremely challenging. The use of combination therapy involving both gene therapy and chemotherapy has resulted in enhanced anti-cancer effects and has become an increasingly important strategy in medicine. This review will cover important design parameters that are incorporated into delivery systems for the co-administration of drug and plasmid-based nucleic acids (pDNA and shRNA), with particular emphasis on polymers as delivery materials. The unique challenges faced by co-delivery systems and the strategies to overcome such barriers will be discussed. In addition, the advantages and disadvantages of combination therapy using separate carrier systems versus the use of a single carrier will be evaluated. Finally, future perspectives in the design of novel platforms for the combined delivery of drugs and genes will be presented.

Multifunctional hyaluronic acid modified graphene oxide loaded with mitoxantrone for overcoming drug resistance in cancer

Multifunctional nanosheets (HA-GO/Pluronic) with targeted chemo-photothermal properties were successfully developed for controlled delivery of mitoxantrone (MIT) to overcome multidrug resistance (MDR). In vitro release profiles displayed that both an acidic environment and a NIR laser could trigger and accelerate the release of a drug, which ensured nanosheets were stable in blood circulation and released MIT within tumor cells under laser irradiation. HA-GO/Pluronic nanosheets were taken up into MCF-7/ADR cells via receptor-mediated endocytosis, which further facilitated escapement of P-gp efflux. Compared with MIT solution, MIT/HA-GO/Pluronic showed greater cytotoxicity and increase in cellular MIT accumulation in MCF-7/ADR cells. Cell apoptosis and cell cycle arrest studies also revealed that MIT/HA-GO/Pluronic was more potent than MIT/GO/Pluronic and MIT solution. The anticancer efficacy in vivo was evaluated in MCF-7 and MCF-7/ADR-bearing mice, and inhibition of tumors by MIT/HA-GO/Pluronic with NIR laser irradiation was the most effective among all MIT formulations. In summary, the MIT/HA-GO/Pluronic system had striking functions such as P-gp reversible inhibitor and anticancer efficacy, and could present a promising platform for drug-resistant cancer treatment.

Gene Therapeutic Approaches to Overcome ABCB1-Mediated Drug Resistance

Multidrug resistance (MDR) to pharmaceutical active agents is a common clinical problem in patients suffering from cancer. MDR is often mediated by over expression of trans-membrane xenobiotic transport molecules belonging to the superfamily of ATP-binding cassette (ABC)-transporters. This protein family includes the classical MDR-associated transporter ABCB1 (MDR1/P-gp). Inhibition of ABC-transporters by low molecular weight compounds in cancer patients has been extensively investigated in clinical trials, but the results have been disappointing. Thus, in the last decades alternative experimental therapeutic strategies for overcoming MDR were under extensive investigation. These include gene therapeutic approaches applying antisense-, ribozyme-, RNA interference-, and CRISPR/Cas9-based techniques. Various delivery strategies were used to reverse MDR in different tumor models in vitro and in vivo. Results and conclusions of these gene therapeutic studies will be discussed.

Light-responsive AIE nanoparticles with cytosolic drug release to overcome drug resistance in cancer cells

A photo-active amphiphilic polymer containing a photosensitizer with aggregation-induced emission (AIE) characteristics was developed for light-responsive cytosolic drug release to overcome drug resistance.

Folate Receptor Targeted Delivery of siRNA and Paclitaxel to Ovarian Cancer Cells via Folate Conjugated Triblock Copolymer to Overcome TLR4 Driven Chemotherapy Resistance

This paper focuses on the ability of a folate-decorated triblock copolymer to deliver a targeted dose of siRNA in order to overcome chemotherapy resistance which can commonly cause complications in ovarian cancer patients. The micelleplexes that are formed upon electrostatic interaction with siRNA are used to deliver siRNA in a targeted manner to SKOV-3 ovarian cancer cells that overexpress folate receptor-α (FRα). The triblock copolymer consists of polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) (PEI-g-PCL-b-PEG-Fol). In this work, polymers of different molecular weights of PEG, as well as different grafting degrees of the (g-PCL-b-PEG-Fol) chains to PEI, were analyzed to optimize targeted siRNA delivery. The polymers, their micelleplexes, and the in vitro performance of the latter were characterized by nuclear magnetic resonance, dynamic light scattering, transmission electron microscopy, flow cytrometry, western blot, confocal microscopy, and in luciferase assays. The different PEI-g-PCL-b-PEG-Fol conjugates showed suitable sizes below 260 nm, especially at N/P 5, which also allowed for full siRNA condensation. Furthermore, flow cytometry and Western blot analysis demonstrated that our best polymer was able to effectively deliver siRNA and that siRNA delivery resulted in efficient protein knockdown of toll-like receptor 4 (TLR4). Consequently, TLR4 knock down within SKOV-3 cells resensitized them toward paclitaxel (PTX) treatment, and apoptotic events increased. This study demonstrates that PEI-g-PCL-b-PEG-Fol conjugates are a reliable delivery system for siRNA and are able to mediate therapeutic protein knockdown within ovarian cancer cells. Additionally, this study provides further evidence to link TLR4 levels to chemotherapy resistance.

Redox-Responsive Polyphosphoester-Based Micellar Nanomedicines for Overriding Chemoresistance in Breast Cancer Cells

Multidrug resistance (MDR) has been recognized as a key factor contributing to the failure of chemotherapy for cancer in the clinic, often due to insufficient delivery of anticancer drugs to target cells. For addressing this issue, a redox-responsive polyphosphoester-based micellar nanomedicine, which can be triggered to release transported drugs in tumor cells, has been developed. The micelles are composed of diblock copolymers with a hydrophilic PEG block and a hydrophobic polyphosphoester (PPE) block bearing a disulfide bond in a side group. After incubating the redox-responsive micelles with drug-resistant tumor cells, the intracellular accumulation and retention of DOX were significantly enhanced. Moreover, after internalization by MDR cancer cells, the disulfide bond in the side group was cleaved by the high intracellular glutathione levels, resulting in a hydrophobic to hydrophilic transition of the PPE block and subsequent disassembly of the micelles. Thus, the encapsulated DOX was rapidly released, and abrogation of drug resistance in the cancer cells was observed in vitro. Moreover, the DOX-loaded redox-responsive micelles exhibited significantly enhanced inhibition of tumor growth in nude mice bearing MCF-7/ADR xenograft tumors via tail vein injection, indicating that such micelles have great potential in overcoming MDR for cancer therapy.

Reducible chimeric polypeptide consisting of octa-D-arginine and tetra-L-histidine peptides as an efficient gene delivery vector

Cationic oligopeptide as a nonviral gene delivery vector has aroused much research interest recently, but its further application is limited by its low transfection efficiency. In the present study, we have created a high-efficiency gene vector by using octa-d-arginine and tetra-l-histidine to form a disulfide cross-linked chimeric polypeptide and used this vector to deliver the therapeutic gene tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) to see whether the gene could be transferred and could exert antitumor effects in vitro and in vivo. The result showed that the newly designed vector was able to condense DNA into nanosized polyplexes effectively, thus facilitating its transmembrane transport, promoting its endosomal escape, and finally enabling degradation within the cell. Our study has demonstrated that this chimeric polypeptide is an effective gene carrier in cancer therapy.