Therapeutic potentials of short interfering RNAs

Lipid nanoparticle technology-mediated therapeutic gene manipulation in the eyes

Millions of people worldwide have hereditary genetic disorders, trauma, infectious diseases, or cancer of the eyes, and many of these eye diseases lead to irreversible blindness, which is a major public health burden. The eye is a relatively small and immune-privileged organ. The use of nucleic acid-based drugs to manipulate malfunctioning genes that target the root of ocular diseases is regarded as a therapeutic approach with great promise. However, there are still some challenges for utilizing nucleic acid therapeutics in vivo because of certain unfavorable characteristics, such as instability, biological carrier-dependent cellular uptake, short pharmacokinetic profiles in vivo (RNA), and on-target and off-target side effects (DNA). The development of lipid nanoparticles (LNPs) as gene vehicles is revolutionary progress that has contributed the clinical application of nucleic acid therapeutics. LNPs have the capability to entrap and transport various genetic materials such as small interfering RNA, mRNA, DNA, and gene editing complexes. This opens up avenues for addressing ocular diseases through the suppression of pathogenic genes, the expression of therapeutic proteins, or the correction of genetic defects. Here, we delve into the cutting-edge LNP technology for ocular gene therapy, encompassing formulation designs, preclinical development, and clinical translation.

Pharmacokinetics, safety, and tolerability of BMS-986263, a lipid nanoparticle containing HSP47 siRNA, in participants with hepatic impairment

BMS-986263 is a retinoid-conjugated lipid nanoparticle delivering small interfering RNA designed to inhibit synthesis of HSP47 protein, a collagen-specific chaperone protein involved in fibrosis development. This is a phase I, open-label, two-part study evaluating pharmacokinetics and safety of BMS-986263 in participants with hepatic impairment (HI). Part 1 (n = 24) of this study enrolled two cohorts with mild and moderate HI and a separate cohort of age- and body mass index (BMI)-matched participants with normal hepatic function. Part 2 enrolled eight participants with severe HI and eight age- and BMI-matched participants with normal hepatic function. All participants received a single intravenous 90 mg BMS-986263 infusion. Compared with normal-matched participants, geometric mean area under the plasma concentration-time curve time zero to the time of the last quantifiable concentration (AUC(0-T) ) and AUC from zero to infinity (AUC(INF) ) of HSP47 siRNA were similar in participants with mild HI and 34% and 163% greater in those with moderate and severe HI, respectively, whereas the maximum plasma concentration was ~25% lower in mild and moderate HI groups but 58% higher in the severe HI group than in the normal group. Adverse events were reported by two of eight, four of eight, and three of eight participants with mild, moderate, or severe HI, respectively; none were reported in the normal-matched group. Overall, single-dose BMS-986263 was generally safe and well-tolerated and dose adjustment is not considered necessary for participants with mild or moderate HI. Although available data do not indicate that dose adjustment should be performed in patients with severe HI; the optimal posology of BMS-986263 in patients with severe HI may be determined later in its clinical development when additional data to establish exposure-safety/efficacy relationship becomes available.

The Role of HIF-1α in Bone Regeneration: A New Direction and Challenge in Bone Tissue Engineering

The process of repairing significant bone defects requires the recruitment of a considerable number of cells for osteogenesis-related activities, which implies the consumption of a substantial amount of oxygen and nutrients. Therefore, the limited supply of nutrients and oxygen at the defect site is a vital constraint that affects the regenerative effect, which is closely related to the degree of a well-established vascular network. Hypoxia-inducible factor (HIF-1α), which is an essential transcription factor activated in hypoxic environments, plays a vital role in vascular network construction. HIF-1α, which plays a central role in regulating cartilage and bone formation, induces vascular invasion and differentiation of osteoprogenitor cells to promote and maintain extracellular matrix production by mediating the adaptive response of cells to changes in oxygen levels. However, the application of HIF-1α in bone tissue engineering is still controversial. As such, clarifying the function of HIF-1α in regulating the bone regeneration process is one of the urgent issues that need to be addressed. This review provides insight into the mechanisms of HIF-1α action in bone regeneration and related recent advances. It also describes current strategies for applying hypoxia induction and hypoxia mimicry in bone tissue engineering, providing theoretical support for the use of HIF-1α in establishing a novel and feasible bone repair strategy in clinical settings.

Progress on siRNA-based gene therapy targeting secondary injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a life-threatening condition with a high mortality rate. For survivors, quality of life is determined by primary and secondary phases of injury. The prospects for injury repair and recovery after ICH are highly dependent on the extent of secondary injury. Currently, no effective treatments are available to prevent secondary injury or its long-term effects. One promising strategy that has recently garnered attention is gene therapy, in particular, small interfering RNAs (siRNA), which silence specific genes responsible for destructive effects after hemorrhage. Gene therapy as a potential treatment for ICH is being actively researched in animal studies. However, there are many barriers to the systemic delivery of siRNA-based therapy, as the use of naked siRNA has limitations. Recently, the Food and Drug Administration approved two siRNA-based therapies, and several are undergoing Phase 3 clinical trials. In this review, we describe the advancements in siRNA-based gene therapy for ICH and also summarize its advantages and disadvantages.

Recent developments in nucleic acid-based therapies for Parkinson's disease: Current status, clinical potential, and future strategies

Parkinson's disease is the second most common progressive neurodegenerative disease diagnosed mainly based on clinical symptoms caused by loss of nigrostriatal dopaminergic neurons. Although currently available pharmacological therapies provide symptomatic relief, however, the disease continues to progress eventually leading to severe motor and cognitive decline and reduced quality of life. The hallmark pathology of Parkinson's disease includes intraneuronal inclusions known as Lewy bodies and Lewy neurites, including fibrillar α-synuclein aggregates. These aggregates can progressively spread across synaptically connected brain regions leading to emergence of disease symptoms with time. The α-synuclein level is considered important in its fibrillization and aggregation. Nucleic acid therapeutics have recently been shown to be effective in treating various neurological diseases, raising the possibility of developing innovative molecular therapies for Parkinson's disease. In this review, we have described the advancements in genetic dysregulations in Parkinson's disease along with the disease-modifying strategies involved in genetic regulation with particular focus on downregulation of α-synuclein gene using various novel technologies, notably antisense oligonucleotides, microRNA, short interfering RNA, short hairpin RNAs, DNA aptamers, and gene therapy of vector-assisted delivery system-based therapeutics. In addition, the current status of preclinical and clinical development for nucleic acid-based therapies for Parkinson's disease have also been discussed along with their limitations and opportunities.

BMS-986263 in patients with advanced hepatic fibrosis: 36-week results from a randomized, placebo-controlled phase 2 trial

BACKGROUND AND AIMS

Hepatic fibrosis secondary to HCV infection can lead to cirrhosis and hepatic decompensation. Sustained virologic response (SVR) is possible with direct-acting antiviral drug regimens; however, patients with advanced fibrosis have an increased risk for HCC. Heat shock protein 47 (HSP47), a key collagen chaperone, has been implicated in fibrosis development. We evaluated the efficacy and safety of BMS-986263, a lipid nanoparticle delivering small interfering RNA designed to degrade HSP47 mRNA, for the treatment of advanced fibrosis.

APPROACH AND RESULTS

NCT03420768 was a Phase 2, randomized (1:1:2), placebo-controlled trial conducted at a hepatology clinic in the United States. Patients with HCV-SVR (for ≥ 1 year) and advanced fibrosis received once-weekly i.v. infusions of placebo or BMS-986263 (45 or 90 mg) for 12 weeks. The primary endpoint was ≥ 1 METAVIR stage improvement at Week 12; key secondary endpoints included Ishak score improvement, pharmacokinetics, fibrosis biomarkers, and safety. All 61 patients completed treatment, and 2/15 (13%, placebo), 3/18 (17%, 45 mg), and 6/28 (21%, 90 mg) had METAVIR improvements of ≥ 1 stage at Week 12. Five patients in the 90-mg arm had Ishak improvements by ≥ 2 stages. BMS-986263 plasma concentrations increased in a generally dose-proportional fashion between BMS-986263 doses, with no notable accumulation with weekly dosing. All adverse events (AEs) were mild or moderate in intensity; most treatment-related AEs were infusion-related reactions in the BMS-986263 arms. At baseline, collagen levels were low, indicating low levels of fibrogenesis in these patients.

CONCLUSIONS

In patients with HCV-SVR, BMS-986263 administration was generally well tolerated through Week 36 and resulted in METAVIR and Ishak score improvements. Further evaluation of BMS-986263 in patients with active fibrogenesis is warranted.

Non-coding RNA therapeutics for cardiac regeneration

A growing body of evidence indicates that cardiac regeneration after myocardial infarction can be achieved by stimulating the endogenous capacity of cardiomyocytes (CMs) to replicate. This process is controlled, both positively and negatively, by a large set of non-coding RNAs (ncRNAs). Some of the microRNAs (miRNAs) that can stimulate CM proliferation is expressed in embryonic stem cells and is required to maintain pluripotency (e.g. the miR-302∼367 cluster). Others also govern the proliferation of different cell types, including cancer cells (e.g. the miR-17∼92 cluster). Additional miRNAs were discovered through systematic screenings (e.g. miR-199a-3p and miR-590-3p). Several miRNAs instead suppress CM proliferation and are involved in the withdrawal of CMs from the cell cycle after birth (e.g. the let-7 and miR-15 families). Similar regulatory roles on CM proliferation are also exerted by a few long ncRNAs. This body of information has obvious therapeutic implications, as miRNAs with activator function or short antisense oligonucleotides against inhibitory miRNAs or lncRNAs can be administered to stimulate cardiac regeneration. Expression of miRNAs can be achieved by gene therapy using adeno-associated vectors, which transduce CMs with high efficiency. More effective and safer for therapeutic purposes, small nucleic acid therapeutics can be obtained as chemically modified, synthetic molecules, which can be administered through lipofection or inclusion in lipid or polymer nanoparticles for efficient cardiac delivery. The notion that it is possible to reprogramme CMs into a regenerative state and that this property can be enhanced by ncRNA therapeutics remains exciting, however extensive experimentation in large mammals and rigorous assessment of safety are required to advance towards clinical application.

The Tumorigenic Effect of Sphingosine Kinase 1 and Its Potential Therapeutic Target

Sphingosine kinase 1 (SPHK1) regulates cell proliferation and survival by converting sphingosine to the signaling mediator sphingosine 1-phosphate (S1P). SPHK1 is widely overexpressed in most cancers, promoting tumor progression and is associated with clinical prognosis. Numerous studies have explored SPHK1 as a promising target for cancer therapy. However, due to insufficient knowledge of SPHK1 oncogenic mechanisms, its inhibitors’ therapeutic potential in preventing and treating cancer still needs further investigation. In this review, we summarized the metabolic balance regulated by the SPHK1/S1P signaling pathway and highlighted the oncogenic mechanisms of SPHK1 via the upregulation of autophagy, proliferation, and survival, migration, angiogenesis and inflammation, and inhibition of apoptosis. Drug candidates targeting SPHK1 were also discussed at the end. This review provides new insights into the oncogenic effect of SPHK1 and sheds light on the future direction for targeting SPHK1 as cancer therapy.

IGFBP‑rP1‑silencing promotes hypoxia‑induced angiogenic potential of choroidal endothelial cells via the RAF/MEK/ERK signaling pathway

Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) has been reported to have various functions in different cellular contexts. Our previous investigation discovered that IGFBP-rP1 inhibited retinal angiogenesis in vitro and in vivo by inhibiting the pro-angiogenic effect of VEGF and downregulating VEGF expression. Recently, IGFBP-rP1 was confirmed to be downregulated in the aqueous humor of patients with neovascular age-related macular degeneration compared with controls; however, its specific role remains unknown. The present study applied the technique of gene silencing, reverse transcription-quantitative PCR, western blotting, cell viability assays, cell motility assays and tube formation assays. Chemical hypoxic conditions and choroidal endothelial (RF/6A) cells were used to explore the effect of IGFBP-rP1-silencing on the phenotype activation of RF/6A cells under hypoxic conditions and to elucidate the underlying mechanisms. siRNA achieved IGFBP-rP1-silencing in RF/6A cells without cytotoxicity. IGFBP-rP1-silencing significantly restored the viability of RF/6A cells in hypoxia and enhanced hypoxia-induced migration and capillary-like tube formation of RF/6A cells. Furthermore, IGFBP-rP1-silencing significantly upregulated the expression of B-RAF, phosphorylated (p)-MEK, p-ERK and VEGF in RF/6A cells under hypoxic conditions; however, these upregulations were inhibited by exogenous IGFBP-rP1. These data indicated that silencing IGFBP-rP1 expression in RF/6A cells effectively promoted the hypoxia-induced angiogenic potential of choroidal endothelial cells by upregulating RAF/MEK/ERK signaling pathway activation and VEGF expression.

Saccharomyces cerevisiae (Baker's Yeast) as an Interfering RNA Expression and Delivery System

The broad application of RNA interference for disease prevention is dependent upon the production of dsRNA in an economically feasible, scalable, and sustainable fashion, as well as the identification of safe and effective methods for RNA delivery. Current research has sparked interest in the use of Saccharomyces cerevisiae for these applications. This review examines the potential for commercial development of yeast interfering RNA expression and delivery systems. S. cerevisiae is a genetic model organism that lacks a functional RNA interference system, which may make it an ideal system for expression and accumulation of high levels of recombinant interfering RNA. Moreover, recent studies in a variety of eukaryotic species suggest that this microbe may be an excellent and safe system for interfering RNA delivery. Key areas for further research and development include optimization of interfering RNA expression in S. cerevisiae, industrial-sized scaling of recombinant yeast cultures in which interfering RNA molecules are expressed, the development of methods for large-scale drying of yeast that preserve interfering RNA integrity, and identification of encapsulating agents that promote yeast stability in various environmental conditions. The genetic tractability of S. cerevisiae and a long history of using this microbe in both the food and pharmaceutical industry will facilitate further development of this promising new technology, which has many potential applications of medical importance.

Epigenetic regulation of anterior segment diseases and potential therapeutics

In recent years, technological advances in sequencing have accelerated our understanding of epigenetics in ocular development and ophthalmic diseases. We now know that epigenetic modifications are necessary for normal ocular development and biological processes such as corneal wound healing and ocular surface repair, while aberrant epigenetic regulation underlies the pathogenesis of a wide range of ocular diseases, including cataracts and various diseases of the ocular surface. As the epigenetics of the eye is a constantly changing field of medicine, this comprehensive review focuses on innovations and scientific discoveries related to epigenetic control of anterior segment diseases that were published in the English literature in the past five years. These recent studies attempt to elucidate therapeutic targets for the anterior segment pathological processes. Already, recent studies have shown therapeutic potential in targeting epigenetic mechanisms of ocular diseases, and new epigenetic therapies are on the verge of being introduced to clinical practice. New drug targets can potentially emerge as we make further discoveries within this field.

Downregulation of survivin by adenovirus-mediated shRNA promotes apoptosis in skin cancer cells

Background

Survivin, a member of the inhibitor of apoptosis protein family, is highly expressed in many cancers and has important roles in inhibiting apoptosis by blocking caspase activation. However, its antitumor effects remain largely unknown. Here we explore the function of survivin in skin cancer.

Methods

We used qPCR and Western blot to examine survivin expression in skin cancer patients and cell line. We generated several survivin shRNA constructs and tested the effects of survivin shRNA on cancer cell viability using MTT assay, flow cytometry, and TUNEL assay.

Results

We found that survivin was upregulated in both skin cancer patients and skin cancer cell line A431. Knockdown survivin via shRNA inhibited cancer cell proliferation and promoted apoptosis in both A431 cell and in vivo xenograft tumor mouse model. The antitumor effect is comparable to resveratrol, a drug known to inhibit cancer progression. Moreover, we showed that inhibition of survivin was able to increase the expression of cleaved caspase 7/caspase 9 and activate the ataxia-telangiectasia mutated-NF-κB pathway in A431 cells.

Conclusion

Survivin-shRNA possesses antitumor abilities in vitro and in vivo by inhibiting the proliferation and promoting apoptosis of A431 cells. It may serve as a potential anticancer target for skin cancer therapy in the future.

Therapeutic Potential of Ribozymes

Recent advances in RNA engineering during the last two decades have supported the development of RNA-based therapeutics targeting a variety of human diseases. The broad scope of these emerging drugs clearly demonstrates the versatility of RNA. Ribozymes have been seen as promising candidates in this area. However, efficient intracellular application of ribozymes remains challenging, and other strategies appear to have outperformed ribozymes as molecular drugs. Nevertheless, trans-cleaving ribozymes have been applied for specific cleavage of target mRNAs in order to inhibit undesired gene expression. Furthermore, ribozymes have been engineered to allow site-directed RNA sequence alterations, enabling the correction of genetic misinformation at the RNA level. This chapter provides an overview of ribozyme-based strategies, highlighting the promises and pitfalls for potential therapeutic applications.

In Vitro and in Vivo RNA Inhibition by CD9-HuR Functionalized Exosomes Encapsulated with miRNA or CRISPR/dCas9

In vitro and in vivo delivery of RNAs of interest holds promise for gene therapy. Recently, exosomes are considered as a kind of rational vehicle for RNA delivery, especially miRNA and/or siRNA, while the loading efficiency is limited. In this study, we engineered the exosomes for RNA loading by constructing a fusion protein in which the exosomal membrane protein CD9 was fused with RNA binding protein, while the RNA of interest either natively harbors or is engineered to have the elements for the binding. By proof-of-principle experiments, we here fused CD9 with HuR, an RNA binding protein interacting with miR-155 with a relatively high affinity. In the exosome packaging cells, the fused CD9-HuR successfully enriched miR-155 into exosomes when miR-155 was excessively expressed. Moreover, miR-155 encapsulated in the exosomes in turn could be efficiently delivered into the recipient cells and recognized the endogenous targets. In addition, we also revealed that the CD9-HuR exosomes could enrich the functional miRNA inhibitor or CRISPR/dCas9 when the RNAs were engineered to have the AU rich elements. Taken together, we here have established a novel strategy for enhanced RNA cargo encapsulation into engineered exosomes, which in turn functions in the recipient cells.

Non-Covalent Associates of siRNAs and AuNPs Enveloped with Lipid Layer and Doped with Amphiphilic Peptide for Efficient siRNA Delivery

Elaboration of non-viral vehicles for delivery of therapeutic nucleic acids, in particular siRNA, into a cell is an actively growing field. Gold nanoparticles (AuNPs) occupy a noticeable place in these studies, and various nanoconstructions containing AuNPs are reported. We aimed our work to the rational design of AuNPs-based siRNA delivery vehicle with enhanced transfection efficiency. We optimized the obtaining of non-covalent siRNAs-AuNPs cores: ionic strength, temperature and reaction time were determined. Formation of cores was confirmed using gel electrophoresis. Stable associates were prepared, and then enveloped into a lipid layer composed of phosphatidylcholine, phosphatidylethanolamine and novel pH-sensitive lipidoid. The constructions were modified with [Str-(RL)₄G-NH₂] peptide (the resulting construction). All intermediate and resulting nanoconstructions were analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) to control their physico-chemical properties. To examine the biological effect of the delivery vehicle, green fluorescent protein (GFP)-expressing human embryonic kidney (HEK) Phoenix cells were incubated with the resulting construction containing anti-GFP siRNA, with the siRNA effect being studied by flow cytometry and confocal microscopy. Transfection of the cells with the resulting construction reduced the GFP fluorescence as efficiently as Lipofectamin 3000. Thus, siRNA vehicle based on non-covalently bound siRNA-AuNP core and enveloped into a lipid layer provides efficient delivery of siRNA into a cell followed by specific gene silencing.

Shock wave-induced permeabilization of mammalian cells

Controlled permeabilization of mammalian cell membranes is fundamental to develop gene and cell therapies based on macromolecular cargo delivery, a process that emerged against an increasing number of health afflictions, including genetic disorders, cancer and infections. Viral vectors have been successfully used for macromolecular delivery; however, they may have unpredictable side effects and have been limited to life-threatening cases. Thus, several chemical and physical methods have been explored to introduce drugs, vaccines, and nucleic acids into cells. One of the most appealing physical methods to deliver genes into cells is shock wave-induced poration. High-speed microjets of fluid, emitted due to the collapse of microbubbles after shock wave passage, represent the most significant mechanism that contributes to cell membrane poration by this technique. Herein, progress in shock wave-induced permeabilization of mammalian cells is presented. After covering the main concepts related to molecular strategies whose applications depend on safer drug delivery methods, the physics behind shock wave phenomena is described. Insights into the use of shock waves for cell membrane permeation are discussed, along with an overview of the two major biomedical applications thereof-i.e., genetic modification and anti-cancer shock wave-assisted chemotherapy. The aim of this review is to summarize 30 years of data showing underwater shock waves as a safe, noninvasive method for macromolecular delivery into mammalian cells, encouraging the development of further research, which is still required before the introduction of this promising tool into clinical practice.

Facile Synthesis, Geometry, and 2'-Substituent-Dependent in Vivo Activity of 5'-(E)- and 5'-(Z)-Vinylphosphonate-Modified siRNA Conjugates

(E)-Vinylphosphonate ((E)-VP), a metabolically stable phosphate mimic at the 5'-end of the antisense strand, enhances the in vivo potency of siRNA. Here we describe a straightforward synthetic approach to incorporate a nucleotide carrying a vinylphosphonate (VP) moiety at the 5'-end of oligonucleotides under standard solid-phase synthesis and deprotection conditions by utilizing pivaloyloxymethyl (POM) protected VP-nucleoside phosphoramidites. The POM protection enhances scope and scalability of 5'-VP-modified oligonucleotides and, in a broader sense, the synthesis of oligonucleotides modified with phosphonate moieties. Trivalent N-acetylgalactosamine-conjugated small interfering RNA (GalNAc-siRNA) comprising (E)-geometrical isomer of VP showed improved RISC loading with robust RNAi-mediated gene silencing in mice compared to the corresponding (Z)-isomer despite similar tissue accumulation. We also obtained structural insights into why bulkier 2'-ribosugar substitutions such as 2'-O-[2-(methylamino)-2-oxoethyl] are well tolerated only when combined with 5'-(E)-VP.

Recent Progress in Stem Cell Modification for Cardiac Regeneration

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity.

Co-delivery of hypoxia inducible factor-1α small interfering RNA and 5-fluorouracil to overcome drug resistance in gastric cancer SGC-7901 cells

BACKGROUND

Drug resistance cancer cells have become a major problem in chemotherapy. To solve this problem, the co-delivery of small interefering RNA (siRNA) and 5-fluorouracil chitosan nanoparticles was employed, aiming to reverse the multidrug resistance of gastric cancer SGC-7901 cells in vitro.

METHODS

Chitosan nanoparticles were prepared using an ionic gel method. siRNA nanoparticles were characterized by gel retardation assays. Particle size and zeta potential were measured to confirm nanoparticle formation. The transfection efficiency of siRNA was determined by flow cytometry and high-content screening. Western blotting and a quantitative real-time-polymerase chain reaction were used to assess the silencing efficiency of siRNA. Accumulation and efflux experiments for rhodamine-123, cell migration experiments, cell sensitivity analyses and cell apoptosis assays were used to determine whether siRNA could reverse multidrug resistance. A systemic toxicity assay was used to evaluate the safety of nanoparticles.

RESULTS

Compared to naked siRNA, the co-delivery system demonstrated a higher transfection efficiency and gene silencing efficiency by inhibiting the efflux of P-glycoprotein and cell migration. Moreover, the combination treatment with siRNA and 5-fluorouracil co-delivered by chitosan nanoparticles can increase the sensitivity of drug resistance cells and cell apoptosis. Finally, the safety of nanoparticles was evaluated in vivo and the results obtained suggested that nanoparticles did not have any obvious toxicity.

CONCLUSIONS

Co-delivery of siRNA and 5-fluorouracil chitosan nanoparticles is an attractive strategy for overcoming multidrug resistance.