Non-viral nanocarriers for siRNA delivery in breast cancer

Osteoporosis therapy using nanoparticles: a review

Osteoporosis, characterized by low bone density and increased risk of fractures, represents a major healthcare challenge. Anti-resorptive and anabolic medications are now used to treat osteoporosis in an effort to reduce bone loss and increase bone mass. Innovative methods are required since current therapies have drawbacks. Promising options for improving bone health and medicine delivery are provided by nanotechnology. Bisphosphonates with tetracyclines and oligopeptides, among other compounds that target the bone, make it easier to provide a particular medication to bone tissue. Additionally, nanocarriers are essential for the administration of both organic and inorganic nanoparticles in the treatment of osteoporosis. Drug encapsulation and controlled release may be done in a variety of ways using organic nanoparticles. Inorganic nanoparticles have special qualities that help in medication transport and bone repair. This review explores the potential of nanoparticle-based strategies in the treatment of osteoporosis.

Off target toxicities and links with physicochemical properties of medicinal products, including antibiotics, oligonucleotides, lipid nanoparticles (with cationic and/or anionic charges). Data review suggests an emerging pattern

Toxicology is an essential part of any drug development plan. Circumnavigating the risk of failure because of a toxicity issue can be a challenge, and failure in late development is extremely costly. To identify potential risks, it requires more than just understanding the biological target. The toxicologist needs to consider a compound's structure, it's physicochemical properties (including the impact of the overall formulation), as well as the biological target (e.g., receptor interactions). Understanding the impact of the physicochemical properties can be used to predict potential toxicities in advance by incorporating key endpoints in early screening strategies and/or used to compare toxicity profiles across lead candidates. This review discussed the risks of off-target and/or non-specific toxicities that may be associated with the physicochemical properties of compounds, especially those carrying dominant positive or negative charges, including amphiphilic small molecules, peptides, oligonucleotides and lipids/liposomes/lipid nanoparticles. The latter of which are being seen more and more in drug development, including the recent Covid pandemic, where mRNA and lipid nanoparticle technology is playing more of a role in vaccine development. The translation between non-clinical and clinical data is also considered, questioning how a physicochemical driven toxicity may be more universal across species, which means that such toxicity may be reassuringly translatable between species and as such, this information may also be considered as a support to the 3 R's, particularly in the early screening stages of a drug development plan.

Biomaterial-based gene therapy

Gene therapy, a medical approach that involves the correction or replacement of defective and abnormal genes, plays an essential role in the treatment of complex and refractory diseases, such as hereditary diseases, cancer, and rheumatic immune diseases. Nucleic acids alone do not easily enter the target cells due to their easy degradation in vivo and the structure of the target cell membranes. The introduction of genes into biological cells is often dependent on gene delivery vectors, such as adenoviral vectors, which are commonly used in gene therapy. However, traditional viral vectors have strong immunogenicity while also presenting a potential infection risk. Recently, biomaterials have attracted attention for use as efficient gene delivery vehicles, because they can avoid the drawbacks associated with viral vectors. Biomaterials can improve the biological stability of nucleic acids and the efficiency of intracellular gene delivery. This review is focused on biomaterial-based delivery systems in gene therapy and disease treatment. Herein, we review the recent developments and modalities of gene therapy. Additionally, we discuss nucleic acid delivery strategies, with a focus on biomaterial-based gene delivery systems. Furthermore, the current applications of biomaterial-based gene therapy are summarized.

Development of lipid nanoparticles and liposomes reference materials (II): cytotoxic profiles

Lipid based nanocarriers are one of the most effective drug delivery systems that is evident from the recent COVID-19 mRNA vaccines. The main objective of this study was to evaluate toxicity of six lipid based formulations with three surface charges-anionic, neutral or cationic, to establish certified reference materials (CRMs) for liposomes and siRNA loaded lipid nanoparticles (LNP-siRNA). Cytotoxicity was assessed by a proliferation assay in adherent and non-adherent cell lines. High concentration of three LNP-siRNAs did not affect viability of suspension cells and LNP-siRNAs were non-toxic to adherent cells at conventionally used concentration. Systematic evaluation using multiple vials and repeated test runs of three liposomes and three LNP-siRNA formulations showed no toxicity in HL60 and A549 cells up to 128 and 16 µg/mL, respectively. Extended treatment and low concentration of LNPs did not affect the viability of suspension cells and adherent cells at 96 h. Interestingly, 80% of A549 and HL60 cells in 3D conditions were viable when treated with cationic LNP-siRNA for 48 h. Taken together, anionic, cationic and neutral lipid formulations were non-toxic to cells and may be explored further in order to develop them as drug carriers.

Insights on prospects of nano-siRNA based approaches in treatment of Cancer

siRNA interference, commonly referred to as gene silence, is a biological mechanism that inhibits gene expression in disorders such as cancer. It may enhance the precision, efficacy, and stability of medicines, especially genetic therapies to some extent. However, obstacles such as the delivery of oligonucleotide drugs to inaccessible areas of the body and the prevalence of severe side effects must be overcome. To maximize their potential, it is thus essential to optimize their distribution to target locations and limit their toxicity to healthy cells. The action of siRNA may be harnessed to delete a similar segment of mRNA that encodes a protein that causes sickness. The absence of an efficient delivery mechanism that shields siRNA from nuclease degradation, delivers it to cancer cells and releases it into the cytoplasm of specific cancer cells without causing side effects is currently the greatest obstacle to the practical implementation of siRNA therapy. This article focuses on combinations of siRNA with chemotherapeutic drug delivery systems for the treatment of cancer and gives an overview of several nanocarrier formulations in both research and clinical applications.

Redox-Responsive Disulfide Cyclic Peptides: A New Strategy for siRNA Delivery

RNA interference (RNAi) is a powerful tool capable of targeting virtually any protein without time-consuming and expensive drug development studies. However, due to obstacles facing efficient and safe delivery, RNAi-based therapeutic approach remains a challenge. Herein, we have designed and synthesized a number of disulfide-constraining cyclic and hybrid peptides using tryptophan and arginine residues. Our hypothesis was that peptide structures would undergo reduction by intracellular glutathione (more abundant in cancer cells) and unpack the small interfering RNA (siRNA) from the peptide/siRNA complexes. A subset of newly developed peptides (specifically, C4 and H4) exhibited effective cellular internalization of siRNA (∼70% of the cell population; monitored by flow cytometry and confocal microscopy), the capability of protecting siRNA against early degradation by nucleases (monitored by gel electrophoresis), minimal cytotoxicity in selected cell lines (studied by cell viability and LC₅₀ calculations), and efficient protein silencing by 70-75% reduction in the expression of targeting signal transducer and activator of transcription 3 (STAT3) in human triple-negative breast cancer (TNBC) MDA-MB-231 cells, analyzed using the Western blot technique. Our results indicate the birth of a promising new family of siRNA delivery systems that are capable of safe and efficient delivery, even in the presence of nucleases.

RNAi-based therapeutics and tumor targeted delivery in cancer

Over the past decade, non-coding RNA-based therapeutics have proven as a great potential for the development of targeted therapies for cancer and other diseases. The discovery of the critical function of microRNAs (miRNAs) has generated great excitement in developing miRNA-based therapies. The dysregulation of miRNAs contributes to the pathogenesis of various human diseases and cancers by modulating genes that are involved in critical cellular processes, including cell proliferation, differentiation, apoptosis, angiogenesis, metastasis, drug resistance, and tumorigenesis. miRNA (miRNA mimic, anti-miRNA/antagomir) and small interfering RNA (siRNA) can inhibit the expression of any cancer-related genes/mRNAs with high specificity through RNA interference (RNAi), thus representing a remarkable therapeutic tool for targeted therapies and precision medicine. siRNA and miRNA-based therapies have entered clinical trials and recently three novel siRNA-based therapeutics were approved by the Food and Drug Administration (FDA), indicating the beginning of a new era of targeted therapeutics. The successful clinical applications of miRNA and siRNA therapeutics rely on safe and effective nanodelivery strategies for targeting tumor cells or tumor microenvironment. For this purpose, promising nanodelivery/nanoparticle-based approaches have been developed using a variety of molecules for systemic administration and improved tumor targeted delivery with reduced side effects. In this review, we present an overview of RNAi-based therapeutics, the major pharmaceutical challenges, and the perspectives for the development of promising delivery systems for clinical translation. We also highlight the passive and active tumor targeting nanodelivery strategies and primarily focus on the current applications of nanoparticle-based delivery formulations for tumor targeted RNAi molecules and their recent advances in clinical trials in human cancers.

siRNA nanohybrid systems: false hope or feasible answer in cancer management

Finding out predisposition and makeup alterations in cancer cells has prompted the exploration of exogenous small interference RNA (siRNA) as a therapeutic agent to deal with cancer. siRNA is subjected to many limitations that hinders its cellular uptake. Various nanocarriers have been loaded with siRNA to improve their cellular transportation and have moved to clinical trials. However, many restrictions as low encapsulation efficiency, nanocarrier cytotoxicity and premature release of siRNA have impeded the single nanocarrier use. The realm of nanohybrid systems has emerged to overcome these limitations and to synergize the criteria of two or more nanocarriers. Different nanohybrid systems that were developed as cellular pathfinders for the exogenous siRNA to target cancer will be illustrated in this review.

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.

Traditional herbal medicine and nanomedicine: Converging disciplines to improve therapeutic efficacy and human health

Traditional herbal medicine (THM), an ancient science, is a gift from nature. For thousands of years, it has helped humans fight diseases and protect life, health, and reproduction. Nanomedicine, a newer discipline has evolved from exploitation of the unique nanoscale morphology and is widely used in diagnosis, imaging, drug delivery, and other biomedical fields. Although THM and nanomedicine differ greatly in time span and discipline dimensions, they are closely related and are even evolving toward integration and convergence. This review begins with the history and latest research progress of THM and nanomedicine, expounding their respective developmental trajectory. It then discusses the overlapping connectivity and relevance of the two fields, including nanoaggregates generated in herbal medicine decoctions, the application of nanotechnology in the delivery and treatment of natural active ingredients, and the influence of physiological regulatory capability of THM on the in vivo fate of nanoparticles. Finally, future development trends, challenges, and research directions are discussed.

Cetuximab-Modified Human Serum Albumin Nanoparticles Co-Loaded with Doxorubicin and MDR1 siRNA for the Treatment of Drug-Resistant Breast Tumors

Background

Breast cancer is the most prevalent cancer among women. Doxorubicin (DOX) is a common chemotherapeutic drug used to treat many different cancers. However, multidrug resistance limits the treatment of breast cancer. MDR1 siRNA (siMDR1) combinatorial therapy has attracted significant attention as a breakthrough therapy for multidrug resistance in tumors. However, naked siRNA is easily degraded by enzymatic hydrolysis requiring an siRNA carrier for its protection. Human serum albumin (HSA) was selected as the carrier due to its excellent biocompatibility, non-toxicity, and non-immunogenicity. Cetuximab was used to modify the HSA nanoparticles in order to target the tumor tissues.

Methods

This study used a central composite design response surface methodology (CCD-RSM) to investigate the optimal formula for HSA NPs preparation. Cex-HSA/DOX/MDR1 siRNA (C-H/D/M) was characterized by dynamic light scattering and transmission electron microscopy. The efficacy of C-H/D/M tumor growth inhibitory activity was investigated in vitro and in vivo using confocal imaging, MTT assay, and an MCF-7/ADR tumor-bearing mice model. RT–qPCR, ELISA analysis, and flow cytometry were used to investigate the in vitro antitumor mechanisms of C-H/D/M.

Results

The diameter and PDI of the C-H/D/M were 173.57 ± 1.30 nm and 0.027 ± 0.004, respectively. C-H/D/M promoted and maintained the sustained release and the uptake of DOX significantly. After transfection, the MDR1 mRNA and P-gp expression levels were down-regulated by 44.31 ± 3.6% (P < 0.01) and 38.08 ± 2.4% (P < 0.01) in an MCF-7/ADR cell line. The fluorescent images of the treated BALB/c nude mice revealed that C-H/D/M achieved targeted delivery of siMDR1 and DOX into the tumor tissue. The in vivo tumor inhibition results demonstrated that the tumor inhibition rate of the C-H/D/M treated group was 54.05% ± 1.25%. The biosafety results indicated that C-H/D/M did not induce significant damages to the main organs in vivo.

Conclusion

C-H/D/M can be used as an ideal non-viral tumor-targeting vector to overcome MDR and enhance the antitumor effect.

Chitosan as possible inhibitory agents and delivery systems in leukemia

Leukemia is a lethal cancer in which white blood cells undergo proliferation and immature white blood cells are seen in the bloodstream. Without diagnosis and management in early stages, this type of cancer can be fatal. Changes in protooncogenic genes and microRNA genes are the most important factors involved in development of leukemia. At present, leukemia risk factors are not accurately identified, but some studies have pointed out factors that predispose to leukemia. Studies show that in the absence of genetic risk factors, leukemia can be prevented by reducing the exposure to risk factors of leukemia, including smoking, exposure to benzene compounds and high-dose radioactive or ionizing radiation. One of the most important treatments for leukemia is chemotherapy which has devastating side effects. Chemotherapy and medications used during treatment do not have a specific effect and destroy healthy cells besides leukemia cells. Despite the suppressing effect of chemotherapy against leukemia, patients undergoing chemotherapy have poor quality of life. So today, researchers are focusing on finding more safe and effective natural compounds and treatments for cancer, especially leukemia. Chitosan is a valuable natural compound that is biocompatible and non-toxic to healthy cells. Anticancer, antibacterial, antifungal and antioxidant effects are examples of chitosan biopolymer properties. The US Food and Drug Administration has approved the use of this compound in medical treatments and the pharmaceutical industry. In this article, we take a look at the latest advances in the use of chitosan in the treatment and improvement of leukemia.

Osteoporosis Remission and New Bone Formation with Mesoporous Silica Nanoparticles

Nanotechnology changed the concept of treatment for a variety of diseases, producing a huge impact regarding drug and gene delivery. Among the different targeted diseases, osteoporosis has devastating clinical and economic consequences. Since current osteoporosis treatments present several side effects, new treatment approaches are needed. Recently, the application of small interfering RNA (siRNA) has become a promising alternative. Wnt/β-catenin signaling pathway controls bone development and formation. This pathway is negatively regulated by sclerostin, which knock-down through siRNA application would potentially promote bone formation. However, the major bottleneck for siRNA-based treatments is the necessity of a delivery vector, bringing nanotechnology as a potential solution. Among the available nanocarriers, mesoporous silica nanoparticles (MSNs) have attracted great attention for intracellular delivery of siRNAs. The mesoporous structure of MSNs permits the delivery of siRNAs together with another biomolecule, achieving a combination therapy. Here, the effectiveness of a new potential osteoporosis treatment based on MSNs is evaluated. The proposed system is effective in delivering SOST siRNA and osteostatin through systemic injection to bone tissue. The nanoparticle administration produced an increase expression of osteogenic related genes improving the bone microarchitecture. The treated osteoporotic mice recovered values of a healthy situation approaching to osteoporosis remission.

Nanotechnology-based siRNA delivery strategies for treatment of triple negative breast cancer

Triple negative breast cancer (TNBC) is a subtype of breast cancer characterized by absence of estrogen (ER) receptor, progesterone (PR) receptor, and human epidermal growth factor-2 (HER-2) receptor. TNBC is an aggressive disease that develops early Chemoresistance. The major pitfall associated is its poor prognosis, low overall survival, high relapse, and mortality as compared to other types of breast cancer. Chemotherapy could be helpful but do not contribute to an increase in survival of patient. To overcome such obstacles, in our article we explored advanced therapy using genes and nanocarrier along with its conjugation to achieve high therapeutic profile with reduced side effect. siRNAs are one of the class of RNA associated with gene silencing. They also regulate the expression of certain proteins that are involved in development of tumor cells. But they are highly unstable. So, for efficient delivery of siRNA, very intelligent, efficient delivery systems are required. Several nanotechnologies based non-viral vectors such as liposome, micelles, nanoparticles, dendrimers, exosomes, nanorods and nanobubbles etc. offers enormous unique properties such as nanometric size range, targeting potential with the capability to link with several targeting moieties for the gene delivery. These non-viral vectors are much safer, effective and efficient system for the delivery of genes along with chemotherapeutics. This review provides an overview of TNBC, conventional and advanced treatment approach of TNBC along with understanding of current status of several nanocarriers used for the delivery of siRNA for the treatment of TNBC.

Plausible role of chitosan in drug and gene delivery against resistant breast cancer cells

Breast cancer is the highest global spread of invasive cancer in women. While significant progress has been made in breast cancer, diagnostic and therapeutic effective prevention and treatment options remain scarce. Concerning chitosan-based chemotherapeutic therapies, the studies reported cell migration resistance, improved drug absorption, membrane interaction and permeability, immune stimulating behavior, and extended in-vitro drug release. However, chitosan has been practically restricted mostly to unmodified forms. Targeted distribution is ensured by chitosan-based ligand conjugated carrier systems in conjunction with active moieties such as DNA, RNA, proteins, and therapeutic agents. The purpose of this context is to emphasize the efficient drug delivery to breast cancer cell lines using chitosan. Chitosan also exhibited excellent capabilities in gene packaging. For the interaction of bioactive molecules and the regulation of the drug release profile, chemical modification of chitosan is beneficial. This article discusses the various chitosan-based ligand conjugated carrier systems. From the studies reviewed it can be concluded that chitosan derivatives are promising materials for targeted and non-viral gene delivery in treatment of breast cancer.

Liposomes as multifaceted delivery system in the treatment of osteoporosis

Introduction: Treatment of osteoporosis with the available drug formulations is still challenging due to multiple associated limitations such as chronic treatment, off-target side effects, poor bone targeting, and low bioavailability. Adopting advanced bone-targeted drug delivery strategies like liposomes is one of the safe and effective approaches for osteoporosis treatment.Areas covered: This review summarizes the applications of liposomes in gene delivery, bone regeneration, bone-targeted delivery, and as a carrier for drug encapsulation in the treatment of osteoporosis. Details of all the supportive studies are discussed here and the bone-specific roles of the strategies like new generation liposomes in osteoporosis are elaborated. The future scope of performing in-depth research on the bone-targeted liposomes is discussed.Expert opinion: Liposomes-based bone-targeted delivery of therapeutics seems to be a promising approach for the effective treatment of osteoporosis. But till date, the tremendous in vitro and in vivo research on liposomes has failed to attain significant progress in their clinical translation. From bench to bedside success of the research an interdisciplinary collaboration between the preclinical and clinical experts engaged at different stages of liposomes development is required.

Gene therapy with caspase-3 small interfering RNA-nanoparticles is neuroprotective after optic nerve damage

Apoptosis, a key mechanism of programmed cell death, is triggered by caspase-3 protein and lowering its levels with gene therapy may rescue cell death after central nervous system damage. We developed a novel, non-viral gene therapy to block caspase-3 gene expression using small interfering RNA (siRNA) delivered by polybutylcyanoacrylate nanoparticles (CaspNPs). In vitro CaspNPs significantly blocked caspase-3 protein expression in C6 cells, and when injected intraocularly in vivo, CaspNPs lowered retinal capsase-3 immunofluorescence by 57.9% in rats with optic nerve crush. Longitudinal, repeated retinal ganglion cell counts using confocal neuroimaging showed that post-traumatic cell loss after intraocular CaspNPs injection was only 36.1% versus 63.4% in lesioned controls. Because non-viral gene therapy with siRNA-nanoparticles can selectively silence caspace-3 gene expression and block apoptosis in post-mitotic neurons, siRNA delivery with nanoparticles may be promising for neuroprotection or restoration of central visual system damage and other neurological disorders. The animal study procedures were approved by the German National Act on the use of experimental animals (Ethic Committee Referat Verbraucherschutz, Veterinärangelegenheiten; Landesverwaltungsamt Sachsen-Anhalt, Halle, Germany, # IMP/G/01-1150/12 and # IMP/G/01-1469/17).

Mechanisms of Resistance to Chemotherapy in Breast Cancer and Possible Targets in Drug Delivery Systems

Breast cancer (BC) is one of the most important cancers worldwide, and usually, chemotherapy can be used in an integrative approach. Usually, chemotherapy treatment is performed in association with surgery, radiation or hormone therapy, providing an increased outcome to patients. However, tumors can develop resistance to different drugs, progressing for a more aggressive phenotype. In this scenario, the use of nanocarriers could help to defeat tumor cell resistance, providing a new therapeutic perspective for patients. Thus, this systematic review aims to bring the molecular mechanisms involved in BC chemoresistance and extract from the previous literature information regarding the use of nanoparticles as potential treatment for chemoresistant breast cancer.

Inorganic-organic Nanomaterials for Therapeutics and Molecular Imaging Applications

Background::

Surface modification of nanoparticles with targeting moieties can be achieved through bioconjugation chemistries to impart new Functionalities. Various polymeric nanoparticles have been used for the formulation of nanoparticles such as naturally-occurring protein cages, virus-like particles, polymeric saccharides, and liposomes. These polymers have been proven to be biocompatible, side effects free and degradable with no toxicity.

Objectives::

This paper reviews available literature on the nanoparticles pharmaceutical and medical applications. The review highlights and updates the customized solutions for selective drug delivery systems that allow high-affinity binding between nanoparticles and the target receptors.

Methods::

Bibliographic databases and web-search engines were used to retrieve studies that assessed the usability of nanoparticles in the pharmaceutical and medical fields. Data were extracted on each system in vivo and in vitro applications, its advantages and disadvantages, and its ability to be chemically and genetically modified to impart new functionalities. Finally, a comparison between naturally occurring and their synthetic counterparts was carried out.

Results::

The results showed that nanoparticles-based systems could have promising applications in diagnostics, cell labeling, contrast agents (Magnetic Resonance Imaging and Computed Tomography), antimicrobial agents, and as drug delivery systems. However, precautions should be taken to avoid or minimize toxic effect or incompatibility of nanoparticles-based systems with the biological systems in case of pharmaceutical or medical applications.

Conclusion::

This review presented a summary of recent developments in the field of pharmaceutical nanotechnology and highlighted the challenges and the merits that some of the nanoparticles- based systems both in vivo and in vitro systems.

Silencing SALL-4 Gene by Transfecting Small Interfering RNA with Targeted Aminoglycoside-Carboxyalkyl Polyethylenimine Nano-Polyplexes Reduced Migration of MCF-7 Breast Cancer Cells

Background:

The application of non-viral systems for delivering genes to cells is becoming a very interesting issue, especially in the treatment of neoplasms such as Breast Cancer (BC). Polymer-based non-viral systems are safe and feasible gene carriers to be used in targeted cancer therapy. SALL4 gene encodes a transcription factor and is overexpressed in some cancers.

Methods:

In this study, carboxyalkylated-PEI25 (25 kDa) was used to deliver plasmids expressing SALL4-siRNA into MCF-7 cells. DLS and AFM were applied to determine the size of nanoparticles. The MTT method was used to assess cytotoxicity, and the efficiency of transfection was confirmed both qualitatively and quantitatively. Finally, the effect of silencing SALL4 was investigated on the migration of MCF7 cells using the scratch test.

Results:

The results showed that transferring the SALL4-siRNA using PEI25G10C50 reduced the expression of the corresponding transcription factor by 14 folds which attenuated the migration of MCF-7 cells by 58%.

Conclusion:

In conclusion, PEI25G10C50 can serve as an effective gene delivery system for treating BC by targeting SALL-4.

Study on mechanism of elemene reversing tumor multidrug resistance based on luminescence pharmacokinetics in tumor cells in vitro and in vivo

While elemene (ELE) can reverse tumor multidrug resistance (MDR), the mechanisms for ELE reversing MDR remain unclear. Numerous studies have suggested that the efflux functionality of ATP-binding cassette (ABC) transporters, not their quantity, is more relevant to tumor MDR. However, no appropriate methods exist for real-time detection of the intracellular drug efflux caused by ABC transporters in vitro, especially in vivo, which hinders the examination of MDR reversal mechanisms. This study directly investigates the correlation between efflux functionality of ABC transporters and MDR reversal via ELE, using d-luciferin potassium salt (d-luc) as the chemotherapeutic substitute to study the intracellular drug efflux. Here, a luciferase reporter assay system combined with bioluminescence imaging confirmed that the efflux of d-luc from MCF-7/DOXFluc cells in vitro and in vivo was significantly reduced by ELE and when combined with Doxorubicin (DOX), ELE showed a synergistically anti-tumor effect in vitro and in vivo. Additionally, the luminescence pharmacokinetics of d-luc in MCF-7/DOXFluc cells and pharmacodynamics of the combined ELE and DOX in vivo showed a great correlation, implying that d-luc might be used as a probe to study ABC transporters-mediated efflux in order to explore mechanisms of traditional Chinese medicines reversing MDR.

Self-Assembled Dual-Targeted Epirubicin-Hybrid Polydopamine Nanoparticles for Combined Chemo-Photothermal Therapy of Triple-Negative Breast Cancer

PURPOSE

Folic acid and cyclic arginylglycylaspartic acid peptides were introduced to the surface of negatively charged lipid-coated hybrid polydopamine-cysteine cores for the delivery of epirubicin (EPI) (E/PCF-NPs). The combined chemo-photothermal therapy using E/PCF-NPs for triple-negative breast cancer was evaluated.

MATERIALS AND METHODS

The temperature elevation and thermal toxicity of nanoparticles were studied. The morphology and properties of E/PCF-NPs were characterized by transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Physicochemical properties, including particle size, zeta potential, drug loading, entrapment efficiency (EE%), stability and in vitro release, were determined. The cell viability, reactive oxygen species (ROS) levels, ratios of oxidized nicotinamide adenine dinucleotide to its reduced form (NAD+/NADH), apoptosis assays, and cellular uptake of E/PCF-NPs were determined on 4T1 cells. Pharmacokinetic studies and tissue distributions were performed and detected by an ultra-high performance liquid chromatography/mass spectrometry system. The antitumor effects of E/PCF-NPs under near-infrared (NIR) laser irradiation were also evaluated.

RESULTS

The sphere-like morphology of E/PCF-NPs showed a high EE%, uniform size of 106.7 nm, remarkable stability, and highly improved cytotoxicity under NIR laser, when compared to that of photothermal treatment alone. In vitro release of EPI from E/PCF-NPs was pH sensitive, and a greater response was achieved under NIR laser irradiation. Compared to chemotherapy or photothermal treatment alone, the combined treatment in vitro significantly inhibited the survival rate of 4T1 cells to 17.7%, induced ROS generation, and reduced NAD+/NADH significantly. Treatment with E/PCF-NPs under irradiation induced 4T1 cell apoptosis in approximately 93.6% cells. In vitro cellular uptake of E/PCF-NPs was time-dependent. The long-circulating and higher tumor accumulation of E/PCF-NPs resulted in complete ablation of breast tumor tissue through the enhanced photothermal effect by NIR laser irradiation-mediated cell apoptosis.

CONCLUSION

E/PCF-NPs show enhanced anti-cancer effects due to synergistic effects of chemotherapy with photothermal therapy and may be potential therapeutic agents for cancer treatment.

Evaluation of Therapeutic Equivalence for the Follow-On Version of Intravenously Administered Non-Biological Complex Drugs

The interchangeability evaluation for generic drugs formulated as intravenous injections normally only requires assessments of pharmaceutical equivalence (PE) when the medicinal products are simple small-molecule drugs. However, intravenously administered non-biological complex drugs (NBCDs), such as liposomes, microsphere suspension, or fat emulsion, have inherent passive disposition selectivity due to their special formulations, thereby the in vivo drug performances are improved. Because of the complexity in formulation, the in vitro pharmaceutical investigations of follow-on NBCDs are more complicated than those required for generic small-molecule drugs. In addition to qualitative and quantitative sameness of the active and inactive ingredients, it is required to comparatively study the static and kinetic microscopic particle-related physiochemical properties of the follow-on NBCDs versus the reference products. Moreover, for complex formulations that have a significant impact on the biodistribution of the drug compound, an in vivo bioequivalence (BE) study is also important. Since NBCDs that demonstrated bioequivalence through the conventional BE approach have been found inequivalent in efficacy or safety to the reference products, pivotal BE studies for follow-on NBCDs are required to take both encapsulated/total drug and free drug as the analytes to address release kinetics and biodistribution of the active pharmacological ingredient in the body. This manuscript reviews the 26 U.S. FDA published product-specific guidelines for intravenous injections. In general, these NBCDs can be stratified into four groups according to their release kinetics and ability of bio-membrane penetration. Group 1 consists of seven small-molecule, non-complex drugs; group 2 included four NBCDs with either microscale particle size or rapid dissolution property; group 3 include five loosely packed NBCDs (fat emulsions) and one quickly released ophthalmic liposomal drug; and the last group contains four cytotoxic liposomal or protein-bound NBCDs and five iron carbohydrate complexes. The requirements of the corresponding guidelines range from simple proof of PE between the test and the reference products, to a collection of studies that demonstrate the key manufacturing process (e.g. liposome loading), the particle- or vehicle-wise static and kinetic physiological characterizations, the dissolution test, and BE evaluation of both total/encapsulated drug form and free drug form between the follow-on NBCDs and their reference products. Such studies are challenging in implementation. Therefore, a variety of alternative approaches are proposed in this article.

Exosome-mediated siRNA delivery to suppress postoperative breast cancer metastasis

High recurrence and metastasis of triple-negative breast cancer (TNBC) after operation is a leading cause of breast cancer related death. The pre-metastatic niche (PMN) is an environment in a secondary organ conducive to the metastasis of a primary tumor. Herein, we identify exosomes from autologous breast cancer cells that show effective lung targeting ability. Based on this, we developed the biomimetic nanoparticles (cationic bovine serum albumin (CBSA) conjugated siS100A4 and exosome membrane coated nanoparticles, CBSA/siS100A4@Exosome) to improve drug delivery to the lung PMN. CBSA/siS100A4@Exosome self-assembled nanoparticles formed homogeneous sizes of ~200 nm, protected siRNA from degradation, and showed excellent biocompatibility. Further in vivo studies showed that CBSA/siS100A4@Exosome had a higher affinity toward lung in comparison to the CBSA/siS100A4@Liposome, and exhibited outstanding gene-silencing effects that significantly inhibited the growth of malignant breast cancer cells. Taken together, these results indicate that CBSA/siS100A4@Exosome self-assembled nanoparticles are a promising strategy to suppress postoperative breast cancer metastasis.

Inhibiting PI3 kinase-γ in both myeloid and plasma cells remodels the suppressive tumor microenvironment in desmoplastic tumors

Phosphoinositide-3-kinases (PI3Ks) are part of signal transducing enzymes that mediate key cellular functions in cancer and immunity. PI3K-γ is crucial for cellular activation and migration in response to certain chemokines. PI3K-γ is highly expressed in myeloid cells and promotes their migration and the production of inflammatory mediators. We found that PI3K-γ was also highly expressed in tumor-associated B cells. IPI-549, the only PI3K-γ inhibitor in clinical development, offers a unique approach to enhance the anti-tumor immune response. We encapsulated IPI-549 in targeted polymeric nanoparticles (NP) and tested its activity in both murine pancreatic cancer and melanoma models. IPI-549 NP significantly decreased tumor growth and prolonged host survival in both models. Importantly, IPI-549 NP treatment reduced the suppressive tumor microenvironment by decreasing both suppressive myeloid and plasma cells in the tumor. We concluded that IPI-549 NP delivery could be a promising method for treating pancreatic cancer and other immune-suppressive tumors.

Single vs. repeated matrix metalloproteinase-13 knockdown with intra-articular short interfering RNA administration in a murine osteoarthritis model

Purpose: Our aims were 1) to estimate the duration of short interfering RNA (siRNA) effect on matrix metalloproteinase-13 (Mmp-13) levels by a single intra-articular injection using a mouse knee osteoarthritis (OA) model and 2) to test whether repeated injections results in any additional suppressive effect on cartilage degradation compared to a single injection. Materials and Methods: OA was induced in 9 weeks old male C57BL/6 mice by destabilization of medial meniscus (DMM). Chemically modified siRNA targeted for Mmp-13 was injected into the knee joint at 1 week post-DMM surgery. Control group of knees received that for non-targeted genes. Synovial tissue was collected to measure Mmp-13 expression levels by quantitative polymerase chain reaction (qPCR) at 2, 3, and 6 weeks after surgery in each group. To test the effect of multiple injections, we created four experiment groups according to the number of injections. Histological assessment of articular cartilage was performed at 8 weeks post-DMM surgery. Results: In the Mmp-13 siRNA-treated group, expression levels of Mmp-13 mRNA were decreased by 40% compared to the control group at 2 weeks after surgery (p = 0.04), before returning to baseline at 3 weeks after surgery. A significant improvement in the histological score was observed in all Mmp-13 siRNA-treated groups compared to the control group (p < 0.05). However, no significant differences were seen between the single and multiple injection group. Conclusions: Our results suggested that the duration of siRNA effect in the knee joint lasts for at least 1 week, and that no further benefit is achieved by multiple injections.

Nanoparticles to Knockdown Osteoporosis-Related Gene and Promote Osteogenic Marker Expression for Osteoporosis Treatment

Osteoporosis is the most common disease involving bone degeneration. Current clinical treatments are not able to offer a satisfying curative effect, so the development of effective treatments is desired. Gene silencing through siRNA delivery has gained great attention as a potential treatment in bone diseases. SOST gene inhibits the Wnt signaling pathway reducing osteoblast differentiation. Consequently, silencing SOST genes with a specific siRNA could be a potential option to treat osteoporosis. Generally, siRNAs have a very short half-life and poor transfection capacity, so an effective carrier is needed. In particular, mesoporous silica nanoparticles (MSNs) have attracted great attention for intracellular delivery of nucleic acids. We took advantage of their high loading capacity to further load the pores with osteostatin, an osteogenic peptide. In this study, we developed a system based on MSNs coated with poly(ethylenimine), which can effectively deliver SOST siRNA and osteostatin inside cells, with the consequent augmentation of osteogenic markers with a synergistic effect. This established the potential utility of MSNs to co-deliver both biomolecules to promote bone formation, this being a potential alternative to treat osteoporosis.

Correlating quantitative tumor accumulation and gene knockdown using SPECT/CT and bioluminescence imaging within an orthotopic ovarian cancer model

Using an orthotopic model of ovarian cancer, we studied the delivery of siRNA in nanoparticles of tri-block copolymers consisting of hyperbranched polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) (hyPEI-g-PCL-b-PEG) with and without a folic acid targeting ligand. A SKOV-3/LUC FRα overexpressing cell line was employed to mimic the clinical manifestations of ovarian cancer. Both targeted and non-targeted micelleplexes were able to effectively deliver siRNA to the primary tumor and its metastases, as measured by gamma scintillation counting and confocal microscopy. Stability of the micelleplexes was demonstrated with a serum albumin binding study. Regarding biodistribution, intravenous (I.V.) administration showed a slight advantage of FRα targeted over non-targeted micelleplex accumulation within the tumor. However, both formulations displayed significant liver uptake. On the other hand, intraperitoneally (I.P.) injected mice showed a modest 6% of the injected dose per gram (ID/g) uptake within the primary and most interestingly also in the metastatic lesions which subsequently resulted in a 62% knockdown of firefly luciferase expression in the tumor after a single injection. While this is, to the best of our knowledge, the first paper that correlates quantitative tumor accumulation in an orthotopic tumor model with in vivo gene silencing, these data demonstrate that PEI-g-PCL-b-PEG-Fol conjugates are a promising option for gene knockdown in ovarian cancer.

Functionalization of Halloysite Nanotubes via Grafting of Dendrimer for Efficient Intracellular Delivery of siRNA

Here, polyamidoamine grafted halloysite nanotubes (PAMAM- g-HNTs) were synthesized for loading of siRNA in order to intracellular delivery of siRNA and treat of breast cancer via gene therapy. The successful grafting of PAMAM on HNTs was confirmed by various analytical methods. The size, zeta potential, and grafting ratio of PAMAM- g-HNTs is ∼206.2 nm, +19.8 mV, and 3.04%, respectively. PAMAM- g-HNTs showed good cytocompatibility toward HUVECs (84.7%) and MCF-7 cells (82.3%) even at high concentration of 100 μg/mL. PAMAM- g-HNTs/siRNA exhibited enhanced cellular uptake efficiency of 94.3% compared with Lipofectamine 2000 (Lipo2000)/siRNA (83.6%). PAMAM- g-HNTs/small interfering RNA-vascular endothelial growth factor (siVEGF) led to 78.0% knockdown of cellular VEGF mRNA and induced 33.6% apoptosis in the MCF-7 cells, which is also much higher than that of Lipo2000/siVEGF. In vivo anti-cancer results demonstrated that PAMAM- g-HNTs/siVEGF treated 4T1-bearing mice showed enhanced anti-cancer efficacy than Lipo2000/siVEGF group. Also, the nanocarrier system showed negligible toxic effects toward the major organs of mice. In vivo fluorescence imaging studies showed that there is a slight decrease in the fluorescence signal of PAMAM- g-HNTs/cy5-siVEGF after 72 h post-injection. Therefore, PAMAM- g-HNTs show promising application as novel nanovectors for siRNA delivery and gene therapy of cancer.

Improved Cell Transfection of siRNA by pH-Responsive Nanomicelles Self-Assembled with mPEG- b-PHis- b-PEI Copolymers

Here, the novel pH-responsive nanomicelles self-assembled with amphipathic meo-poly(ethylene glycol)- b-poly(l-histidine)- b-polyethylenimine (mPEG- b-PHis- b-PEI, EHE) copolymers based on hydrophobic interaction of PHis with deprotonation of imidazoles were developed for siRNA transfection. The cationic nanomicelles could electrostatically compact siRNA into stable EHE/siRNA nanoplexes with a hydrodynamic diameter of ∼190 nm and present a low toxicity in normal physiological condition (pH ∼ 7.4). Different from pH-irresponsive ECE/siRNA nanoplexes based on mPEG- b-poly(ε-caprolactone)- b-PEI (ECE), the EHE/siRNA nanoplexes exhibited a higher cellular uptake along with an increased ζ-potential (from +18 to +32 mV) when the pH changed from 7.4 to 6.8 (extracellular acidic microenvironments). After cell internalization, the EHE/siRNA nanoplexes also exhibited an enhanced nanostructural disassembling and release of siRNA from lysosomal acidic microenvironments (pH ∼ 5.5). Furthermore, it was demonstrated that the EHE/siEGFR nanoplexes downregulated the expression levels of the corresponding mRNA and protein more efficiently than ECE/siEGFR in HeLa cells. The improved siRNA silencing effects of EHE/siEGFR nanoplexes resulted from the higher cellular uptake and enhanced endosomal/lysosomal escape, which is associated with the pH-responsive disassembly of nanostructure as well as the synergistic "proton sponge" effects of PHis and PEI in EHE copolymers. Therefore, the pH-responsive EHE nanomicelles would be promising and potential carriers for cell transfection of siRNA.

Conjugate Polyplexes with Anti-Invasive Properties and Improved siRNA Delivery In Vivo

This study reports on a simple method to prepare siRNA-polycation conjugate polyplexes by in situ thiol-disulfide exchange reaction. The conjugate polyplexes are prepared using thiol-terminated siRNA and a bioreducible branched polycationic inhibitor of the CXCR4 chemokine receptor (rPAMD). The rPAMD-SS-siRNA conjugate polyplexes exhibit improved colloidal stability and resistance against disassembly with heparin, serum, and physiological salt concentrations when compared with control conventional rPAMD/siRNA polyplexes. Coating the polyplexes with human serum albumin masks the positive surface charge and contributes to the enhanced in vitro gene silencing and improved safety in vivo. The conjugate polyplexes display improved in vivo reporter gene silencing following intravenous injection in tumor-bearing mice. Because the conjugate polyplexes retained the ability of rPAMD to inhibit CXCR4 and restrict cancer cell invasion, the developed systems show promise for future combination anti-metastatic siRNA therapies of cancer.

E-cadherin: Its dysregulation in carcinogenesis and clinical implications

E-cadherin is a transmembrane glycoprotein which connects epithelial cells together at adherens junctions. In normal cells, E-cadherin exerts its tumour suppressing role mainly by sequestering β-catenin from its binding to LEF (Lymphoid enhancer factor)/TCF (T cell factor) which serves the function of transcribing genes of the proliferative Wnt signaling pathway. Despite the ongoing debate on whether the loss of E-cadherin is the cause or effect of epithelial-mesenchymal transition (EMT), E-cadherin functional loss has frequently been associated with poor prognosis and survival in patients of various cancers. The dysregulation of E-cadherin expression that leads to carcinogenesis happens mostly at the epigenetic level but there are cases of genetic alterations as well. E-cadherin expression has been linked to the cellular functions of invasiveness reduction, growth inhibition, apoptosis, cell cycle arrest and differentiation. Studies on various cancers have shown that these different cellular functions are also interdependent. Recent studies have reported a rapid expansion of E-cadherin clinical relevance in various cancers. This review article summarises the multifaceted effect E-cadherin expression has on cellular functions in the context of carcinogenesis as well as its clinical implications in diagnosis, prognosis and therapeutics.

Delivery Pathway Regulation of 3',3″-Bis-Peptide-siRNA Conjugate via Nanocarrier Architecture Engineering

Small interfering RNA (siRNA) has been continuously explored for clinical applications. However, neither nanocarriers nor conjugates have been able to remove the obstacles. In this study, we employed a combined nanochemistry strategy to optimize its delivery dilemma, where different interactions and assembly modes were cooperatively introduced into the forming process of siRNA/lipids nanoplexes. In the nanoplexes, the 3',3″-bis-peptide-siRNA conjugate (pp-siRNA) and gemini-like cationic lipids (CLDs) were employed as dual regulators to improve their bio-behavior. We demonstrated that the "cicada pupa"-shaped nanoplexes of MT-pp-siRNA/CLDs (MT represented the mixed two-phase method) exhibited more compact multi-sandwich structure (∼25 layers), controllable size (∼150 nm), and lower zeta potential (∼22 mV) than other comparable nanoplexes and presented an increased siRNA protection and stability. Significantly, the nanoplex was internalized into melanoma cells by almost caveolae-mediated endocytosis and macropinocytosis (∼99.46%), and later reduced/avoided lysosomal degradation. Finally, the nanoplex facilitated the silencing of mRNA of the mutant B-Raf protein (down by ∼60%). In addition, pp-siRNA had a high intracellular sustainability, a significantly prolonged circulating time, and accumulation in tumor tissues in vivo. Our results have demonstrated that the combined approach can improve the intracellular fate of siRNA, which opens up novel avenues for efficient siRNA delivery.

Alternative Splicing in Breast Cancer and the Potential Development of Therapeutic Tools

Alternative splicing is a key molecular mechanism now considered as a hallmark of cancer that has been associated with the expression of distinct isoforms during the onset and progression of the disease. The leading cause of cancer-related deaths in women worldwide is breast cancer, and even when the role of alternative splicing in this type of cancer has been established, the function of this mechanism in breast cancer biology is not completely decoded. In order to gain a comprehensive view of the role of alternative splicing in breast cancer biology and development, we summarize here recent findings regarding alternative splicing events that have been well documented for breast cancer evolution, considering its prognostic and therapeutic value. Moreover, we analyze how the response to endocrine and chemical therapies could be affected due to alternative splicing and differential expression of variant isoforms. With all this knowledge, it becomes clear that targeting alternative splicing represents an innovative approach for breast cancer therapeutics and the information derived from current studies could guide clinical decisions with a direct impact in the clinical advances for breast cancer patients nowadays.

The use of nanoparticulates to treat breast cancer

Breast cancer is a major ongoing public health issue among women in both developing and developed countries. Significant progress has been made to improve the breast cancer treatment in the past decades. However, the current clinical approaches are invasive, of low specificity and can generate severe side effects. As a rapidly developing field, nanotechnology brings promising opportunities to human cancer diagnosis and treatment. The use of nanoparticulate-based platforms overcomes biological barriers and allows prolonged blood circulation time, simultaneous tumor targeting and enhanced accumulation of drugs in tumors. Currently available and clinically applicable innovative nanoparticulate-based systems for breast cancer nanotherapies are discussed in this review.

Molecular Mechanisms and Biological Functions of siRNA

One of the most important advances in biology has been the discovery that siRNA (small interfering RNA) is able to regulate the expression of genes, by a phenomenon known as RNAi (RNA interference). The discovery of RNAi, first in plants and Caenorhabditis elegans and later in mammalian cells, led to the emergence of a transformative view in biomedical research. siRNA has gained attention as a potential therapeutic reagent due to its ability to inhibit specific genes in many genetic diseases. siRNAs can be used as tools to study single gene function both in vivo and in-vitro and are an attractive new class of therapeutics, especially against undruggable targets for the treatment of cancer and other diseases. The siRNA delivery systems are categorized as non-viral and viral delivery systems. The non-viral delivery system includes polymers; Lipids; peptides etc. are the widely studied delivery systems for siRNA. Effective pharmacological use of siRNA requires 'carriers' that can deliver the siRNA to its intended site of action. The carriers assemble the siRNA into supramolecular complexes that display functional properties during the delivery process.

Mesoporous Silica Nanoparticles as Carriers for Intracellular Delivery of Nucleic Acids and Subsequent Therapeutic Applications

Nucleic acids, including DNA, microRNA (miRNA), small interfering RNA (siRNA), and antisense oligonucleotide (ASO), are powerful gene regulators, which have been demonstrated as promising drug candidates for therapeutic treatments. Nevertheless, poor cellular membrane permeability and serum stability have greatly hindered the applications of nucleic acids in biomedicine. To address these issues, associate carriers that can encapsulate and protect nucleic acids are urgently required. Mesoporous silica nanoparticles (MSNs or MSNPs), which are nanomaterials with excellent biocompatibility, large surface area for functionalization, and tunable pore size for encapsulating different cargos, are emerging as novel and ideal biomaterials for different biomedical applications. In this review paper, we focus on the applications of MSNs in nucleic acid delivery and nucleic acid-guided therapeutic treatments. General strategies for the preparation of nucleic acid-MSN complexes will be firstly introduced, followed by a summary of recent applications of MSNs in nucleic acid delivery and nucleic acid-guided therapeutics.

Knockdown of antiapoptotic genes in breast cancer cells by siRNA loaded into hybrid nanoparticles

Tumorigenesis is related to an imbalance in controlling mechanisms of apoptosis. Expression of the genes BCL-2 and BCL-xL results in the promotion of cell survival by inhibiting apoptosis. Thus, a novel approach to suppress antiapoptotic genes is the use of small interfering RNA (siRNA) in cancer cells. However, there are some limitations for the application of siRNA such as the need for vectors to pass the cell membrane and deliver the nucleic acid. In this study CaP-siRNA-PEG-polyanion hybrid nanoparticles were developed to promote siRNA delivery to cultured human breast cancer cells (MCF-7) in order to evaluate whether the silencing of antiapoptotic genes BCL-2 and BCL-xL by siRNA would increase cancer cell death. After 48 h of incubation the expression of BCL-2 and BCL-xL genes decreased to 49% and 23%, respectively. The siRNA sequence used induced cancer cell death at a concentration of 200 nM siRNA after 72 h of incubation. As the targeted proteins are related to the resistance to chemotherapeutic drugs, the nanocarriers systems were also tested in the presence of doxorubicin (DOX). The results showed a significant reduction in the CC₅₀ of the DOX, after silencing the antiapoptotic genes. In addition, an increase in apoptotic cell counts for both incubations conditions was observed as well. In conclusion, silencing antiapoptotic genes such as BCL-2 and BCL-xL through the use of siRNA carried by hybrid nanoparticles showed to be effective in vitro, and presents a promising strategy for pre-clinical analysis, especially when combined with DOX against breast cancer.

Highly Efficient and Safe Delivery of VEGF siRNA by Bioreducible Fluorinated Peptide Dendrimers for Cancer Therapy

RNA interference (RNAi) has a great promise in treating various acquired and hereditary diseases. However, it remains highly desirable to develop new delivery system to circumvent complex extra- and intracellular barriers for successful clinical translation. Here, we report on a versatile polymeric vector, bioreducible fluorinated peptide dendrimers (BFPD), for efficient and safe small interfering RNA (siRNA) delivery. In virtue of skillfully integrating all of the unique advantages of reversible cross-linking, fluorination, and peptide dendrimers, this novel vector can surmount almost all extra- and intracellular barriers associated with local siRNA delivery through highly improved physiological stability and serum resistance, significantly increased intratumoral enrichment, cellular internalization, successful facilitation of endosomal escape, and cytosolic siRNA release. BFPD polyplexes, carrying small interfering vascular endothelial growth factor (siVEGF), demonstrated excellent VEGF silencing efficacy (∼65%) and a strong capability for inhibiting HeLa cell proliferation. More importantly, these polyplexes showed superior performance in long-term enrichment in the tumor sites and had a high level of tumor growth inhibition. Furthermore, these polyplexes not only exhibited excellent in vivo antitumor efficacy but also demonstrated superior biocompatibility, compared with LPF2000, both in vivo and in vitro. These findings indicate that BFPD is an efficient and safe siRNA delivery system and has remarkable potential for RNAi-based cancer treatment.

Dermal/transdermal delivery of small interfering RNA and antisense oligonucleotides- advances and hurdles

A diverse array of nucleic acids has been studied by several researchers for the management of several diseases. Among these compounds, small interfering RNA and antisense oligonucleotides have attracted considerable attention. Antisense oligonucleotides are synthetic single stranded strings of nucleic acids that bind to RNA and thereby alter or reduce expression of the target RNA while siRNAs, on the other hand, are double-stranded RNA molecules which can hybridize with a specific mRNA sequence and block the translation of numerous genes. One of the main obstacles in the dermal or transdermal delivery of these compounds is their low skin permeability. In this review, various techniques used to enhance the delivery of these molecules into or across the skin are described and in some cases, the correlation between enhanced dermal/transdermal delivery and therapeutic efficacy is highlighted.

Development of flexible nanocarriers for siRNA delivery into tumor tissue

Various non-viral delivery systems for small interfering RNAs (siRNA) have been developed. Such delivery systems generally exhibit tightly formed spherical structures. While such carriers have demonstrated good transfection activity in mono-layered cell systems, effects against solid tumors are often less apparent and difficult to demonstrate, likely due to the rigid structures of the carriers, which may prevent penetration to deeper regions within tumor tissue. Herein, we developed a flexible nanocarrier (FNC) system that is able to penetrate to deeper regions within tumor tissue. Specifically, we employed previously found flexible polyplexes comprised of siRNA and poly-l-lysine as wick structures for the preparation of FNCs. FNCs were constructed by coating the wick structures with lipids using a liposomal membrane fusion method. The diameters of the resulting FNCs were ca. 170nm, and the shapes were non-spherical. Lipid coating was confirmed using a nuclease resistance assay. Furthermore, FNCs showed significant RNA interference effects, comparable to Lipofectamine 2000, in a mono-layered cell system. To accelerate tumor penetration, the FNC surface was modified with polyethylene glycol (PEG) and the tight junction opener peptide AT1002. Surface-modified FNCs demonstrated effective penetrability into a cancer spheroid. Thus, we developed a novel and unique tumor-penetrable siRNA FNC system.

Chitosan-based nanoparticles for survivin targeted siRNA delivery in breast tumor therapy and preventing its metastasis

Nanoparticle-mediated small interfering RNA (siRNA) delivery is a promising therapeutic strategy in various cancers. However, it is difficult to deliver degradative siRNA to tumor tissue, and thus a safe and efficient vector for siRNA delivery is essential for cancer therapy. In this study, poly(ethylene glycol)-modified chitosan (PEG-CS) was synthesized successfully for delivering nucleic acid drug. We deemed that PEGylated CS could improve its solubility by forming a stable siRNA loaded in nanoparticles, and enhancing transfection efficiency of siRNA-loaded CS nanoparticles in cancer cell line. The research results showed that siRNA loaded in PEGylated CS (PEG-CS/siRNA) nanoparticles with smaller particle size had superior structural stability in the physical environment compared to CS nanoparticles. The data of in vitro antitumor activity revealed that 4T1 tumor cell growth was significantly inhibited and cellular uptake of PEG-CS/siRNA nanoparticles in 4T1 cells was dramatically enhanced compared to naked siRNA groups. The results from flow cytometry and confocal laser scanning microscopy showed that PEG-CS/siRNA nanoparticles were more easily taken up than naked siRNA. Importantly, PEG-CS/siRNA nanoparticles significantly reduced the growth of xenograft tumors of 4T1 cells in vivo. It has been demonstrated that the PEG-CS is a safe and efficient vector for siRNA delivery, and it can effectively reduce tumor growth and prevent metastasis.

Internalization of Vectored Liposomes in a Culture of Poorly Differentiated Tumor Cells

Internalization of liposomal nanocontainers conjugated with monoclonal antibodies to VEGF, VEGFR2 (KDR), and proteins overproduced in the tumor tissue was studied in vitro on cultures of poorly differentiated tumor cells. Comparative analysis of accumulation of vectored liposomes in the tumor cells was performed by evaluating co-localization of labeled containers and cell organelles by laser scanning confocal microscopy. We observed nearly 2 times more active penetration and accumulation of liposomes vectored with antibodies in the tumor cells in comparison with non-vectored liposomes. Selective clathrin-dependent penetration of vectored liposomes into tumor cells was demonstrated by using pharmacological agents inhibiting endocytosis.

Delivery strategies and potential targets for siRNA in major cancer types

Small interfering RNA (siRNA) has gained attention as a potential therapeutic reagent due to its ability to inhibit specific genes in many genetic diseases. For many years, studies of siRNA have progressively advanced toward novel treatment strategies against cancer. Cancer is caused by various mutations in hundreds of genes including both proto-oncogenes and tumor suppressor genes. In order to develop siRNAs as therapeutic agents for cancer treatment, delivery strategies for siRNA must be carefully designed and potential gene targets carefully selected for optimal anti-cancer effects. In this review, various modifications and delivery strategies for siRNA delivery are discussed. In addition, we present current thinking on target gene selection in major tumor types.

Systemic delivery of siRNA by hyaluronan-functionalized calcium phosphate nanoparticles for tumor-targeted therapy

In this study, hyaluronan (HA)-functionalized calcium phosphate nanoparticles (CaP-AHA/siRNA NPs) were developed for an injectable and targetable delivery of siRNA, which were prepared by coating the alendronate-hyaluronan graft polymer (AHA) around the surface of calcium phosphate-siRNA co-precipitates. The prepared CaP-AHA/siRNA NPs had a uniform spherical core-shell morphology with an approximate size of 170 nm and zeta potential of -12 mV. The coating of hydrophilic HA improved the physical stability of nanoparticles over one month due to the strong interactions between phosphonate and calcium. In vitro experiments demonstrated that the negatively charged CaP-AHA/siRNA NPs could effectively deliver EGFR-targeted siRNA into A549 cells through CD44-mediated endocytosis and significantly down-regulate the level of EGFR expression. Also, the internalized CaP-AHA/siRNA NPs exhibited a pH-responsive release of siRNA, indicating that the acidification of lysosomes probably facilitated the disassembling of nanoparticles and the resultant ions sharply increased the inner osmotic pressure and thus expedited the release of siRNA from late lysosomes into the cytoplasm. Furthermore, in vivo tumor therapy demonstrated that high accumulation of CaP-AHA/siEGFR NPs in tumor led to a significant tumor growth inhibition with a specific EGFR gene silencing effect after intravenous administration in nude mice xenografted with A549 tumor, along with a negligible body weight loss. These results suggested that the CaP-AHA/siRNA NPs could be an effective and safe systemic siRNA delivery system for a RNAi-based tumor targeted therapy strategy.

Synthesis and characterization of Fe3O4-PEG-LAC-chitosan-PEI nanoparticle as a survivin siRNA delivery system

The limited effectiveness of the conventional methods for cancer treatment makes the researchers to find novel safe and effective therapeutic strategies. One of these strategies is to use small interfering RNAs (siRNAs). A major challenge here is the siRNA delivery into the cells. The purpose of this study was to design and prepare a biocompatible, biodegradable, and safe nanosized particle for siRNA delivery into human breast cancer MCF-7 and leukemia K562 cells. Chemically synthesized magnetic nanoparticles containing polyethyleneglycol-lactate polymer (PEG-LAC), chitosan, and polyethyleneimine (PEI) were successfully prepared and used as a gene delivery vehicle. The nanoparticles were characterized by Fourier transform infrared spectroscopy and zeta potential. The Fe3O4-PEG-LAC-chitosan-PEI nanoparticle showed efficient and stable survivin siRNA loading in gel retardation assay. The cytotoxicity of the prepared nanoparticle was studied using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay and was compared with that of mitoxantrone (MTX) in combination with the prepared siRNA delivery system to evaluate the possible synergic effect of MTX and survivin siRNA. The nanoparticles with and without noncomplementary siRNA showed low toxicity against both cell lines; however, a twofold decrease was observed in cell survival percent after MTX addition to MCF-7 cells treated with either nanoparticle itself or complexed with noncomplementary siRNA. While survivin siRNA nanoplex caused threefold decrease in the cell survival percent, its combination with MTX did not result in a significant increase in the cytotoxic effect. Therefore, Fe3O4-PEG-LAC-chitosan-PEI nanoparticle should be considered as a potential carrier for enhanced survivin siRNA delivery into MCF-7 and K562 cells.

Systemic delivery of siRNA by T7 peptide modified core-shell nanoparticles for targeted therapy of breast cancer

Systemic delivery of siRNA is the most challenging step to transfer RNAi to clinical application for breast cancer therapy. In this study, the tumor targeted, T7 peptide modified core-shell nanoparticles (named as T7-LPC/siRNA NPs) were constructed to achieve effective systemic delivery of siRNA. The core-shell structure of T7-LPC/siRNA NPs enables them to encapsulate siRNA in the core and protect it from RNase degradation during circulation. In vitro cellular uptake and gene silencing experiments demonstrated that T7-LPC/siEGFR NPs could deliver EGFR siRNA into breast cancer cells through receptor mediated endocytosis and effectively down-regulate the EGFR expression. In vivo distribution study proved the T7-LPC/siRNA NPs could deliver fluorescence labeled siRNA to the tumor site more efficiently than the non-targeted PEG-LPC/siRNA NPs after intravenous administration. Furthermore, the experiments of in vivo tumor therapy confirmed that intravenous administration of T7-LPC/siEGFR NPs led to an effective EGFR down-regulation and an obvious inhibition of breast tumor growth, with little activation of immune responses and negligible body weight loss. These results suggested that T7-LPC/siRNA NPs could be an effective and safe systemic siRNA delivery system for RNAi-based breast cancer therapy.