siRNA Delivery In Cancer Therapy Research Articles

In vitro study on the inflammatory response of chitosan nanoparticles as a potential siRNA carrier targeting towards osteosarcoma cells

Abstract There have been significant developments in the use of siRNA in the silencing of cancer-allied target proteins with substantial apoptotic effects. Nevertheless, the challenges regarding siRNA delivery for cancer therapy remain a major concern for taking these therapies successfully from laboratory to in vivo studies. Biomaterials are defined traditionally as any material that is used for either medical or dental applications that contact the host cells in any form, such as a drug carrier a device, or as a prosthesis towards the replacement of damaged tissues. The main issues to be fulfilled by the biomaterial for clinical applications are biocompatibility, bioactivity, ability to carry drug to target site, inflammatory responses and other factors based on its application. The present study focuses on the in vitro inflammatory response to the CS nanoparticles using RAW 264.7 and bone marrow derived macrophage cells. Additionally, the in vitro release kinetics of siRNA with varying concentrations and pH, transfection efficacy and biocompatibility were also investigated. The results of siRNA cumulative release increased at pH 5 and 3, which may be corresponding to the protonation, and a delayed release was seen at 7, which was ascribed to unprotonated amine groups inside the CS. The results of release kinetics confirmed a sustained release of siRNA from CS NPs. Considering that CS is a biocompatible polymer, it typically has little impact/damage on cells, as numerous researchers have observed during in vitro experiments. Inflammatory studies were carried out in vitro with RAW 264.7 and BMC cells derived from mice. The gene and protein expression studies showed that the materials might cause some slight inflammation on exposure with both RAW 264.7 and BMC cells in vitro, which is completely negligible. However, putting together the overall data it can be concluded that CS NPs can be a promising material for in vivo applications, which is in agreement with the results of other researchers, but the only concern being its ability to carry siRNA and protect it from nuclease and other enzymatic attacks.

Biomimetic cell membrane-coated nanocarriers for targeted siRNA delivery in cancer therapy.

Small interfering RNA (siRNA) therapeutics for cancer are a focus of increasing research interest. However, the major obstacle to their clinical application is the targeted delivery of siRNA to cancer cells at desirable levels. Cell membrane-coated nanocarriers have the advantage of combining the properties of both cell membranes and nanoparticles (NPs). In this review, we highlight the most common RNAi therapeutics and the extracellular and intracellular barriers to siRNA delivery. Moreover, we discuss clinical applications of different cell membrane-coated nanocarriers for targeted siRNA delivery, including cancer cell membranes (CCMs), platelet membranes, erythrocyte membranes, stem cell membranes, exosome membranes, and hybrid membranes. Taken together, biomimetic cell membrane-coated nanotechnology is a promising strategy for targeted siRNA delivery for cancer treatment.

Development of amino acid-modified biodegradable lipid nanoparticles for siRNA delivery

The use of siRNA therapeutics to treat cancer is a very promising approach. However, specific delivery of siRNAs to tumors remains a major challenge. The recent success of siRNA delivery to the liver has incentivized the development of biomaterials for siRNA delivery into tumors. Here, we report a new class of amino acid-modified lipids for siRNA delivery to cancer cells. Eight lipids were developed by headgroup modification with histidine and lysine. The lipids were screened in PC3-luciferase stable cells for gene silencing and cellular cytotoxicity study. The best lipid LHHK shows a pKa of 6.08, which is within the optimal pKa range of lipid nanoparticles (LNPs) for siRNA delivery. The LHHK LNP protects siRNA from serum degradation for up to 24 h and shows higher endosomal release and better cellular uptake compared to other lysine-modified lipids in PC3 cells. The LHHK LNP exhibits significant silencing activity of IKKα and IKBKE in prostate cancer and pancreatic cancer, respectively. Moreover, the LHHK LNP encapsulating IKBKE siRNA inhibits cell proliferation of pancreatic cancer cells and suppresses the tumor progression in a pancreatic cancer mouse model. Statement of significanceLipid nanoparticle (LNP) is a promising platform for siRNA delivery. However, LNP is generally associated with high systemic toxicity. As a result, efficient and biodegradable lipids are highly needed for siRNA-based cancer therapy. Herein, we develop amino acid-modified biodegradable lipids. These lipids show very low cellular toxicity and high transfection efficiency. The best lipid LHHK shows a pKa of 6.08, which is within the optimal pKa range of LNPs for siRNA delivery. The LHHK LNP efficiently silences IKKα and IKBKE in prostate and pancreatic cancer, respectively. Moreover, the LHHK LNP encapsulating IKBKE siRNA inhibits cell proliferation and suppresses tumor growth of pancreatic cancer in vivo. These results suggest that amino acid-modified lipids possess a great potential for siRNA delivery in cancer therapy.

Tumour-derived extracellular vesicle membrane hybrid lipid nanovesicles enhance siRNA delivery by tumour-homing and intracellular freeway transportation.

Extracellular vesicles (EVs) have been proved a promising small interfering RNA (siRNA) delivery vehicle to mediate gene‐silencing. Tumour‐derived extracellular vesicles (TDEVs) as genetic exchange vectors in the tumour microenvironment, enable intercellular communication for a wide range of endogenous cargo molecules, such as RNAs and proteins. However, the oncogenic cargo of TDEVs limits their application in siRNA delivery for cancer therapy. Herein, we isolated TDEVs from hepatocellular carcinoma (HCC) cells and derived TDEV membranes by abandoning their content. Innovative TDEV membrane hybrid lipid nanovesicles (LEVs) were then fabricated by fusion of TDEV membranes and phospholipids to realize precise delivery to tumours and highly efficient transfection of siRNA. The TDEV membranes endow LEVs with ‘homing’ targeting ability, facilitating specific internalisation into parent HCC cells primarily through heparan sulfate proteoglycan‐mediated pathways. Unlike conventional lipid‐based nanovesicles, LEVs can bypass the endosomal degradation pathway, boost the delivery of siRNA through the Golgi and endoplasmic reticulum (ER) intracellular ‘freeway’ transportation, achieving a 1.7‐fold improvement in siRNA transfection efficiency compared with liposomes. Additionally, siRNA loaded LEVs were demonstrated to enhance the antitumour efficacy in HCC bearing mice through effective gene silencing in the tumour sites. Our results highlight the potential application of the TDEV membrane‐derived nanovesicles as an advanced siRNA delivery strategy for cancer therapy.

Environment-Responsive Lipid/siRNA Nanoparticles for Cancer Therapy.

RNA interference (RNAi) is a promising technology to regulate oncogenes for treating cancer. The primary limitation of siRNA for clinical application is the safe and efficacious delivery of therapeutic siRNA into target cells. Lipid-based delivery systems are developed to protect siRNA during the delivery process and to facilitate intracellular uptake. There is a significant progress in lipid nanoparticle systems that utilize cationic and protonatable amino lipid systems to deliver siRNA to tumors. Among these lipids, environment-responsive lipids are a class of novel lipid delivery systems that are capable of responding to the environment changes during the delivery process and demonstrate great promise for clinical translation for siRNA therapeutics. Protonatable or ionizable amino lipids and switchable lipids as well as pH-sensitive multifunctional amino lipids are the presentative environment-responsive lipids for siRNA delivery. These lipids are able to respond to environmental changes during the delivery process to facilitate efficient cytosolic siRNA delivery. Environment-responsive lipid/siRNA nanoparticles (ERLNP) are developed with the lipids and are tested for efficient delivery of therapeutic siRNA into the cytoplasm of cancer cells to silence target genes for cancer treatment in preclinical development. This review summarizes the recent developments in environment-response lipids and nanoparticles for siRNA delivery in cancer therapy.

Anti-HER2 functionalized graphene oxide as survivin-siRNA delivery carrier inhibits breast carcinoma growth in vitro and in vivo.

BackgroundThe success of gene therapy is mostly dependent on the development of gene carrier. Graphene oxide (GO) possesses excellent aqueous solubility and biocompatibility, which is important for its biochemical and medical applications. Our previous work proved that GO can deliver siRNA into cells efficiently and downregulate the expression of desired protein.MethodsIn this study, a novel delivery carrier, GO-R8/anti-HER2 (GRH), was developed by conjugating octaarginine (R8) and anti-HER2 antibody with GO as a tumor active-targeting vector for survivin-siRNA delivery.ResultsGRH/survivin-siRNA formed nanoglobes of 195±10 nm in diameter. Real-time polymerase chain reaction analysis revealed that survivin messenger RNA expression showed a 42.4%±2.69% knockdown. The expression of survivin protein was downregulated to 50.86%±2.94% in enzyme-linked immunosorbent assay. In MTT tests, GRH exhibited no testable cytotoxicity. In vivo, GRH/survivin-siRNA showed gene silencing and inhibition of tumor growth.ConclusionThe in vitro and in vivo results consistently demonstrated that GRH/survivin-siRNA has potential to be an efficient gene silencing carrier for siRNA delivery in cancer therapy.

PEGylated DC-Chol/DOPE cationic liposomes containing KSP siRNA as a systemic siRNA delivery Carrier for ovarian cancer therapy

Although siRNA-mediated downregulation technology has been highly successful in suppressing the expression of any disease-related gene, systemic delivery of siRNA for the clinical applications remains challenging, especially in the use of cancer therapy. DC-Chol/DOPE cationic liposomes as one of the most attractive vehicles for gene delivery have been widely exploited for transfection of siRNA into cells, but complexity of systemic delivery has allowed only their direct injection into local targets due to the formation of aggregations with negatively-charged blood components. Herein, we demonstrate the effects of PEGylation on DC-Chol/DOPE cationic liposomes for systemic siRNA delivery in cancer therapy. In contrast to non-PEGylated DC-Chol/DOPE-siRNA lipoplexes, PEGylated DC-Chol/DOPE-siRNA lipoplexes reduce the excretion by kidneys and scavenging in liver, prolonging the circulation time in vivo, and ultimately increase their preferential tumor accumulation. Therefore, systemic injection of PEGylated DC-Chol/DOPE liposomes loaded with siRNA against kinesin spindle protein (KSP) gene exhibited a high level of target gene silencing at tumor sites and substantial suppression of tumor growth. Furthermore, systemically administered PEGylated lipoplexes did not lead to any activation of innate immune responses in the immunocompetent mice. These results suggest the potential of PEGylated DC-Chol/DOPE liposomes as a systemic delivery carrier for siRNA-mediated cancer therapy.

Reactive oxygen species (ROS)-responsive nanomedicine for RNAi-based cancer therapy.

Although much effort has been dedicated to the development of efficient siRNA delivery for cancer therapy, delivery nanomaterials that can particularly respond to reactive oxygen species (ROS), which are overproduced in the tissue and mitochondria of cancer cells, are still rare for the clinical translation of RNA interference (RNAi)-based therapy. To this end, we developed a ROS-responsive boronic vehicle with a lipid envelope for systemic vascular endothelial growth factor (VEGF) siRNA delivery so as to improve RNAi cancer therapy. We found that the efficiency of siRNA delivery largely relied on the ROS responsiveness of the carrier we have developed to mediate timely siRNA release, the PEG-functionalized lipid layer to shield the surface charge of polyplexes as well as the ability of the phenylboronic moiety to stabilize siRNA. The unique carrier nanostructure provides the efficient systemic transportation of siRNA to the tumor site for effective knockdown of the VEGF, which resulted in a significant antiangiogenesis effect and the effective inhibition of tumor growth in vivo. The current study defines a new systemic delivery strategy for siRNA by cooperatively integrating multifunctional lipid coatings with the ROS-responsive boronic polymer, which may potentially benefit RNAi-based therapy in the dawning era of precision nanomedicine for cancer therapy.

Liposomes Incorporating Transferrin and Stearic Acid-modified Octa-arginine for siRNA Delivery.

Liposomes incorporating stearic acid-modified octa-arginine (StA-R8) and conjugated to transferrin (Tf) were synthesized and evaluated for delivery of small interfering RNA (siRNA) against survivin. Characteristics, cytotoxicity, cellular uptake and biological activity of liposomes complexed to survivin siRNA were investigated. Tf-conjugated liposomes were shown to have reduced cytotoxicity and improved delivery efficiency for siRNA into cancer cells compared to non-conjugated StA-R8 liposomes. These data suggest that Tf-conjugated StA-R8 liposomes are promising vehicles for siRNA delivery in cancer therapy.

The pH-Triggered Triblock Nanocarrier Enabled Highly Efficient siRNA Delivery for Cancer Therapy.

Small interfering RNA (siRNA) therapies have been hampered by lack of delivery systems in the past decades. Nowadays, a few promising vehicles for siRNA delivery have been developed and it is gradually revealed that enhancing siRNA release from endosomes into cytosol is a very important factor for successful delivery. Here, we designed a novel pH-sensitive nanomicelle, PEG-PTTMA-P(GMA-S-DMA) (PTMS), for siRNA delivery. Owing to rapid hydrolysis in acidic environment, PTMS NPs underwent hydrophobic-to-hydrophilic transition in endosomes that enabled combination of proton sponge effect and raised osmotic pressure in endosomes, resulting in vigorous release of siRNAs from endosomes into cytosol. In vitro results demonstrated that PTMS/siRNA complexes exhibited excellent gene silencing effects in several cell lines. Their gene silencing efficiency could reach ~91%, ~87% and ~90% at the N/P ratio of 50/1 in MDA-MB-231, A549 and Hela cells respectively, which were better than that obtained with Lipofectamine 2000. The highly efficient gene silencing was then proven from enhanced siRNA endosomal release, which is mainly attributed to pH-triggered degradation of polymer and acid-accelerated siRNA release. In vivo experiments indicated that NPs/siRNA formulation rapidly accumulated in tumor sites after i.v. injection. Tumor growth was effectively inhibited and ~45% gene knockdown efficacy was determined at the siRRM2 dose of 1mg/kg. Meanwhile, no significant toxicity was observed during the whole treatment. We also found that PTMS/siRNA formulations could lead to significant gene silencing effects in liver (~63%) and skin (~80%) when injected by i.v. and s.c., respectively. This research work gives a rational strategy to optimize siRNA delivery systems for tumor treatments.

Nanoparticles for siRNA-Based Gene Silencing in Tumor Therapy.

Gene silencing through RNA interference (RNAi) has emerged as a potential strategy in manipulating cancer causing genes by complementary base-pairing mechanism. Small interfering RNA (siRNA) is an important RNAi tool that has found significant application in cancer therapy. However due to lack of stability, poor cellular uptake and high probability of loss-of-function due to degradation, siRNA therapeutic strategies seek safe and efficient delivery vehicles for in vivo applications. The current review discusses various nanoparticle systems currently used for siRNA delivery for cancer therapy, with emphasis on liposome based gene delivery systems. The discussion also includes various methods availed to improve nanoparticle based-siRNA delivery with target specificity and superior efficiency. Further this review describes challenges and perspectives on the development of safe and efficient nanoparticle based-siRNA-delivery systems for cancer therapy.

Delivery of siRNA Using Lipid Nanoparticles Modified with Cell Penetrating Peptide.

Clinical development of siRNA has been hindered by the lack of an effective delivery system. Here, we report the construction of a novel siRNA delivery system, sTOLP, which is based on cell penetrating peptide oleoyl-octaarginine (OA-R8) modified multifunctional lipid nanoparticles. sTOLP nanoparticles are composed of a protamine complexed siRNA core, OA-R8, cationic and PEGylated lipids, and transferrin as a targeting ligand. sTOLP formulation was optimized and characterized in vitro and showed excellent gene silencing activity. In vivo, siRNA encapsulated in sTOLP exhibited potent tumor inhibition (61.7%) and was preferentially taken up by hepatocytes and tumor cells in HepG2-bearing nude mice without inducing immunogenicity or hepatic or renal toxicity. Furthermore, sTOLP-loaded siRNA had stability in circulation greater than that of free siRNA. These data demonstrated potential utility of sTOLP-mediated siRNA delivery in cancer therapy.

Biodegradable Multiamine Polymeric Vector for siRNA Delivery.

The gene silencing activity of small interfering RNA (siRNA) has led to their use as tools for target validation and as potential therapeutics for a variety of diseases. A major challenge is the development of vectors with high delivery efficiency and low toxicity. Although poly(ethylenimine) (PEI) has been regarded as the most promising polymeric vector for nucleic acid delivery, the nonbiodegradable structure greatly hinders its clinical application. In the present study, a diblock copolymer, PEG-PAsp(DIP-DETA), of poly(ethylene glycol) (PEG) and poly(L-aspartic acid) (PAsp) randomly grafted with pH-sensitive 2-(diisopropylamino)ethylamine (DIP) and diethylenetriamine (DETA) groups was synthesized via ring-opening polymerization and aminolysis reaction. Similar to polyethylenimine (PEI), the copolymer possesses a multiamine structure that not only allows effective siRNA complexation at neutral pH but also facilitates lysosomal release of siRNA via a proton buffering effect. Moreover, the poly(L-aspartic acid) backbone renders the vector biodegradability, which is not achievable with PEI. This novel polymeric vector can mediate effective intracellular siRNA delivery in various cancer cells. Consequently, the delivery of BCL-2 siRNA resulted in target gene silencing, inducing apoptosis and inhibiting the growth of cancer cells. These results show the potential of this non-PEI based polymeric vector with proton buffering capacity and biodegradability for siRNA delivery in cancer therapy.

Matrix metalloproteinase 2-responsive micelle for siRNA delivery

Systemic delivery of small interfering RNA (siRNA) into cancer cells remains the major obstacle to siRNA drug development. An ideal siRNA delivery vehicle for systemic administration should have long circulation time in blood, accumulate at tumor site, and sufficiently internalize into cancer cells for high-efficiency of gene silence. Herein, we report a core–shell Micelleplex delivery system that made from block copolymer bearing poly(ethylene glycol) (PEG), matrix metalloproteinase 2 (MMP-2)-degradable peptide PLG*LAG, cationic cell penetrating peptide polyarginine r9 and poly(ε-caprolactone) (PCL) for siRNA delivery. We show clear evidences in vitro and in vivo to prove that the micelle carrying siRNA can circulate enough time in blood, enrich accumulation at tumor sites, shed the PEG layer when triggered by tumor overexpressing MMP-2, and then the exposing cell penetrating peptide r9 enhanced cellular uptake of siRNA. Accordingly, this design strategy enhances the inhibition of breast tumor growth following systemic injection of this system carrying siRNA against Polo-like kinase 1, which demonstrating this Micelleplex can be a potential delivery system for systemic siRNA delivery in cancer therapy.

Tumor-Targeting Transferrin Nanoparticles for Systemic Polymerized siRNA Delivery in Tumor-Bearing Mice

Transferrin (TF) is widely used as a tumor-targeting ligand for the delivery of anticancer drugs because the TF receptor is overexpressed on the surface of various fast-growing cancer cells. In this article, we report on TF nanoparticles as an siRNA delivery carrier for in vivo tumor-specific gene silencing. To produce siRNA carrying TF nanoparticles (NPs), both TF and siRNA were chemically modified with sulfhydryl groups that can build up self-cross-linked siRNA-TF NPs. Self-polymerized 5'-end thiol-modified siRNA (poly siRNA, psi) and thiolated transferrin (tTF) were spontaneously cross-linked to form stable NPs (psi-tTF NPs) under optimized conditions, and they could be reversibly degraded to release functional monomeric siRNA molecules under reductive conditions. Receptor-mediated endocytosis of TF induced rapid tumor-cell-specific uptake of the psi-tTF NPs, and the internalized NPs resulted in a downregulation of the target protein in red-fluorescent-protein-expressing melanoma cancer cells (RFP/B16F10) with negligible cytotoxicity. After systemic administration, the psi-tTF NPs showed marked accumulation at the tumor, leading to successful target-gene silencing in vivo. This psi-tTF NP system provided a safe and effective strategy for in vivo systemic siRNA delivery for cancer therapy.

Recent Developments in Nanoparticle-Based siRNA Delivery for Cancer Therapy

RNA interference (RNAi) is a gene regulation mechanism initiated by RNA molecules that enables sequence-specific gene silencing by promoting degradation of specific mRNAs. Molecular therapy using small interfering RNA (siRNA) has shown great therapeutic potential for diseases caused by abnormal gene overexpression or mutation. The major challenges to application of siRNA therapeutics include the stability and effective delivery of siRNA in vivo. Important progress in nanotechnology has led to the development of efficient siRNA delivery systems. In this review, the authors discuss recent advances in nanoparticle-mediated siRNA delivery and the application of siRNA in clinical trials for cancer therapy. This review will also offer perspectives on future applications of siRNA therapeutics.

A mesoporous silica nanoparticle – PEI – Fusogenic peptide system for siRNA delivery in cancer therapy

RNA interference (RNAi) is widely regarded as a promising technology for disease treatment, yet one major obstacle for its clinical application is the lack of efficient siRNA delivery vehicles. In this study, we described a magnetic mesoporous silica nanoparticles (M-MSNs)-based, polyelectrolyte (polyethylenimine, PEI) and fusogenic peptide (KALA)-functionalized siRNA delivery system (denoted as M-MSN_siRNA@PEI-KALA), which was highly effective for initiating target gene silencing both in vitro and in vivo. The construction of this delivery system began with the encapsulation of siRNA within the mesopores of M-MSNs, followed by the coating of PEI on the external surface of siRNA-loaded M-MSNs and the chemical conjugation of KALA peptides. The as-prepared delivery vehicles, with notable siRNA protective effect and negligible cytotoxicity, could be easily internalized into cells, readily escape from the endolysosomes and release the loaded siRNA into the cytoplasm. As a result, the knockdown of enhanced green fluorescent protein (EGFP) and vascular endothelial growth factor (VEGF) in tumor cells were observed, both with excellent RNAi efficiencies. In the following in vivo experiments, the intratumoral injection of M-MSN_VEGF siRNA@PEI-KALA significantly inhibited the tumor growth, possibly by the suppression of neovascularization in tumors. To sum up, we have established a highly effective MSNs-based delivery system, which has great potential to serve as therapeutic siRNA formulation for cancer treatment.

Significance and applications of nanoparticles in siRNA delivery for cancer therapy

RNAi is a powerful gene silencing process that holds great promise in cancer therapy by the use of siRNA. The aim of this review is to give an outline on different approaches to deliver siRNA and to describe the advantages and disadvantages of these systems. The prospects for siRNA are to be substantially better than other therapies, as they are easily applicable to any therapeutic target. They also promise potent gene inhibition with exquisite selectivity, down to the level of a single nucleotide polymorphism, and can easily identify offending proteins or variants by screening across a gene sequence. The main obstacle of using RNAi technology in cancer treatment is to protect such a fragile and quickly metabolized biological molecule and to efficiently deliver it in vivo to the target cells. Therefore, there is a requirement for new systems, such as nanoparticles, for siRNA delivery to help the siRNAs reach, and improve their biodistribution in, target tissues.

Lipid-Based Nanoparticles for siRNA Delivery in Cancer Therapy: Paradigms and Challenges

RNA interference (RNAi) is a specific gene-silencing mechanism that can be mediated by the delivery of chemical synthesized small-interfering RNA (siRNA). RNAi might constitute a novel therapeutic approach for cancer treatment because researchers can easily design siRNA molecules to inhibit, specifically and potently, the expression of any protein involved in tumor initiation and progression. Despite all the potential of siRNA as a novel class of drugs, the limited cellular uptake, low biological stability, and unfavorable pharmacokinetics of siRNAs have limited their application in the clinic. Indeed, blood nucleases easily degrade naked siRNAs, and the kidneys rapidly eliminate these molecules. Furthermore, at the level of target cells, the negative charge and hydrophilicity of siRNAs strongly impair their cellular internalization. Therefore, the translation of siRNA to the clinical setting is highly dependent on the development of an appropriate delivery system, able to ameliorate siRNA pharmacokinetic and biodistribution properties. In this regard, major advances have been achieved with lipid-based nanocarriers sterically stabilized by poly(ethylene glycol) (PEG), such as the stabilized nucleic acid lipid particles (SNALP). However, PEG has not solved all the major problems associated with siRNA delivery. In this Account, the major problems associated with PEGylated lipid-based nanoparticles, and the different strategies to overcome them are discussed. Although PEG has revolutionized the field of nanocarriers, cumulative experience has revealed that upon repeated administration, PEGylated liposomes lose their ability to circulate over long periods in the bloodstream, a phenomenon known as accelerated blood clearance. In addition, PEGylation impairs the internalization of the siRNA into the target cell and its subsequent escape from the endocytic pathway, which reduces biological activity. An interesting approach to overcome such limitations relies on the design of novel exchangeable PEG-derivatized lipids. After systemic administration, these lipids can be released from the nanoparticle surface. Moreover, the design and synthesis of novel cationic lipids that are more fusogenic and the use of internalizing targeting ligands have contributed to the emergence of novel lipid-based nanoparticles with remarkable transfection efficiency.

A biodegradable amphiphilic and cationic triblock copolymer for the delivery of siRNA targeting the acid ceramidase gene for cancer therapy

One of the key challenges in the development of RNA interference-based cancer therapy is the lack of an efficient delivery system for synthetic small interfering RNAs (siRNAs) that would enable efficient uptake by tumor cells and allow for significant knockdown of a target transcript in vivo. Here, we describe a micelleplex system based on an amphiphilic and cationic triblock copolymer, which can systemically deliver siRNA targeting the acid ceramidase (AC) gene for cancer therapy. This triblock copolymer, consisting of monomethoxy poly(ethylene glycol), poly(ε-caprolactone) and poly(2-aminoethyl ethylene phosphate), self-assembles into micellar nanoparticles (MNPs) in aqueous solution with an average diameter of 60 nm and a zeta potential of approximately 48 mV. The resulting micelleplex, formed by the interaction of MNPs and siRNA, was effectively internalized by BT474 breast cancer cells and siRNA was subsequently released, resulting in significant gene knockdown. This effect was demonstrated by significant down-regulation of luciferase expression in BT474-luciferase cells which stably express luciferase, and suppression of AC expression in BT474 cells at both the transcriptional and protein level, following delivery of specific siRNAs by the micelleplex. Furthermore, a micelleplex carrying siRNA targeting the AC (micelleplexsiAC) gene was found to induce remarkable apoptosis and reduce the proliferation of cancer cells. Systemic delivery of micelleplexsiAC significantly inhibited tumor growth in a BT474 xenograft murine model, with depressed expression of AC and no positive activation of the innate immune response, suggesting therapeutic promise for micelleplex siRNA delivery in cancer therapy.