Folate-decorated PEGylated triblock copolymer as a pH/reduction dual-responsive nanovehicle for targeted intracellular co-delivery of doxorubicin and Bcl-2 siRNA

siRNA-guided dual-targeting nanocarrier for breast cancer treatment

AIMS

This study aimed to develop a thermoplastic polyurethane-oleic acid-based nanosystem (TPU-Ole NPs) incorporating siRNA and curcumin (CUR) to overcome multidrug resistance in breast cancer by silencing the c-myc gene.

METHODS

TPU-Ole and CUR-loaded NPs were prepared via solvent evaporation and coated with poly-L-lysine (PLL) for siRNA attachment. NPs were characterised by dynamic light scattering (DLS) for mean diameter, polydispersity index (PDI), and zeta potential (ZP). Encapsulation (EE) and loading efficiencies (LE) were measured by NanoDrop. Release (pH 5.0; 7.4) and storage stability (pH 7.4) were evaluated using the eppendorf method. siRNA binding was confirmed by agarose gel electrophoresis. Gene silencing and apoptosis were assessed by RT-PCR and flow cytometry.

RESULTS

Mean diameter, PDI, and ZP of NPs were 170 ± 2 nm, 0.011 ± 0.080, and -27.5 ± 0.11 mV. EE and LE were 75 ± 0.12 and 14.2 ± 0.06%. Sustained release and good stability were observed.

CONCLUSION

siRNA-CUR-NPs efficiently silenced c-myc and induced apoptosis in MCF-7 cells.

Targeted co-delivery nanosystem based on methotrexate, curcumin, and PAMAM dendrimer for improvement of the therapeutic efficacy in cervical cancer

The simultaneous administration of multiple drugs within identical nanocarriers to cancer cells or tissues can result in the effective action of drugs at reduced concentrations. In this investigation, PAMAM dendrimers (G4-PAMAM) were employed to link with methotrexate (MTX) using DCC/NHS chemistry and followed by the entrapment of curcumin (Cur) within it. The establishment of covalent bonds between MTX and the PAMAM dendrimer led to PAMAM-MTX interaction, verified and described through FT-IR. Various techniques were employed to evaluate the structural properties of the prepared Cur-PAMAM-MTX NC. The Cur-PAMAM-MTX NC, after preparation, exhibited a particle size of 249 nm, with an encapsulation efficiency (EE) of ~ 81% for Cur. The cumulative in vitro release of Cur-loaded NC indicated a controlled release influenced by time and pH. The cell study results revealed that Cur-PAMAM-MTX NC exhibited significantly higher cytotoxicity than free MTX, Cur, and other formulations tested in vitro. The synergistic effect of co-delivery of MTX and Cur by PAMAM significantly increased cytotoxicity. Besides, the significant ROS level rising has been shown in the treated cells with MTX-PAMAM-Cur. Considering these findings, the co-delivery NC shows promise for additional in vitro investigations and possesses the capacity to function as an effective framework for the combined delivery of MTX and Cur in cervical cancer chemotherapy.

A redox-responsive self-assembling COA-4-arm PEG prodrug nanosystem for dual drug delivery suppresses cancer metastasis and drug resistance by downregulating hsp90 expression

Metastasis and resistance are main causes to affect the outcome of the current anticancer therapies. Heat shock protein 90 (Hsp90) as an ATP-dependent molecular chaperone takes important role in the tumor metastasis and resistance. Targeting Hsp90 and downregulating its expression show promising in inhibiting tumor metastasis and resistance. In this study, a redox-responsive dual-drug nanocarrier was constructed for the effective delivery of a commonly used chemotherapeutic drug PTX, and a COA-modified 4-arm PEG polymer (4PSC) was synthesized. COA, an active component in oleanolic acid that exerts strong antitumor activity by downregulating Hsp90 expression, was used as a structural and functional element to endow 4PSC with redox responsiveness and Hsp90 inhibitory activity. Our results showed that 4PSC/PTX nanomicelles efficiently delivered PTX and COA to tumor locations without inducing systemic toxicity. By blocking the Hsp90 signaling pathway, 4PSC significantly enhanced the antitumor effect of PTX, inhibiting tumor proliferation and invasiveness as well as chemotherapy-induced resistance in vitro. Remarkable results were further confirmed in vivo with two preclinical tumor models. These findings demonstrate that the COA-modified 4PSC drug delivery nanosystem provides a potential platform for enhancing the efficacy of chemotherapies.

Recent advances in peptide-based therapeutic strategies for breast cancer treatment

Breast cancer is the leading cause of cancer-related fatalities in female worldwide. Effective therapies with low side effects for breast cancer treatment and prevention are, accordingly, urgently required. Targeting anticancer materials, breast cancer vaccines and anticancer drugs have been studied for many years to decrease side effects, prevent breast cancer and suppress tumors, respectively. There are abundant evidences to demonstrate that peptide-based therapeutic strategies, coupling of good safety and adaptive functionalities are promising for breast cancer therapy. In recent years, peptide-based vectors have been paid attention in targeting breast cancer due to their specific binding to corresponding receptors overexpressed in cell. To overcome the low internalization, cell penetrating peptides (CPPs) could be selected to increase the penetration due to the electrostatic and hydrophobic interactions between CPPs and cell membranes. Peptide-based vaccines are at the forefront of medical development and presently, 13 types of main peptide vaccines for breast cancer are being studied on phase III, phase II, phase I/II and phase I clinical trials. In addition, peptide-based vaccines including delivery vectors and adjuvants have been implemented. Many peptides have recently been used in clinical treatments for breast cancer. These peptides show different anticancer mechanisms and some novel peptides could reverse the resistance of breast cancer to susceptibility. In this review, we will focus on current studies of peptide-based targeting vectors, CPPs, peptide-based vaccines and anticancer peptides for breast cancer therapy and prevention.

Potentiation of Folate-Functionalized PLGA-PEG nanoparticles loaded with metformin for the treatment of breast Cancer: possible clinical application

AIM

Folate receptor expression increase up to 30% in breast cancer cells and could be used as a possible ligand to couple to folate-functionalized nanoparticles. Metformin (Met) is an anti-hyperglycemic agent whose anti-cancer properties have been formerly reported. Consequently, in the current study, we aimed to synthesize and characterize folate-functionalized PLGA-PEG NPs loaded with Met and evaluate the anti-cancer effect against the MDA-MB-231 human breast cancer cell line.

METHODS

FA-PLGA-PEG NPs were synthesized by employing the W1/O/W2 technique and their physicochemical features were evaluated by FE-SEM, TEM, FTIR, and DLS methods. The cytotoxic effects of free and Nano-encapsulated drugs were analyzed by the MTT technique. Furthermore, RT-PCR technique was employed to assess the expression levels of apoptotic and anti-apoptotic genes.

RESULT

MTT result indicated Met-loaded FA-PLGA-PEG NPs exhibited cytotoxic effects in a dose-dependently manner and had more cytotoxic effects relative to other groups. The remarkable down-regulation (hTERT and Bcl-2) and up-regulation (Caspase7, Caspase3, Bax, and p53) gene expression were shown in treated MDA-MB-231 cells with Met-loaded FA-PLGA-PEG NPs.

CONCLUSION

Folate-Functionalized PLGA-PEG Nanoparticles are suggested as an appropriate approach to elevate the anticancer properties of Met for improving the treatment effectiveness of breast cancer cells.

Nanoparticles design considerations to co-deliver nucleic acids and anti-cancer drugs for chemoresistance reversal

Chemoresistance and hence the consequent treatment failure is considerably challenging in clinical cancer therapeutics. The understanding of the genetic variations in chemoresistance acquisition encouraged the use of gene modulatory approaches to restore anti-cancer drug efficacy. Many smart nanoparticles are designed and optimized to mediate combinational therapy between nucleic acid and anti-cancer drugs. This review aims to define a rational design of such co-loaded nanocarriers with the aim of chemoresistance reversal at various cellular levels to improve the therapeutic outcome of anticancer treatment. Going through the principles of therapeutics loading, physicochemical characteristics tuning, and different nanocarrier modifications, also looking at combination effectiveness on chemosensitivity restoration. Up to now, these emerging nanocarriers are in development status but are expected to introduce outstanding outcomes.

Current Advancements in Self-assembling Nanocarriers-Based siRNA Delivery for Cancer Therapy

Different therapeutic practices for treating cancers have significantly evolved to compensate and/or overcome the failures in conventional methodologies. The demonstrated potentiality in completely inhibiting the tumors and in preventing cancer relapse has made nucleic acids therapy (NAT)/gene therapy as an attractive practice. This has been made possible because NAT-based cancer treatments are highly focused on the fundamental mechanisms - i.e., silencing the expression of oncogenic genes responsible for producing abnormal proteins (via messenger RNAs (mRNAs)). However, the future clinical translation of NAT is majorly dependent upon the effective delivery of the exogenous nucleic acids (especially RNAs - e.g., short interfering RNAs (siRNAs) - herein called biological drugs). Moreover, nano-based vehicles (i.e., nanocarriers) are involved in delivering them to prevent degradation and undesired bioaccumulation while enhancing the stability of siRNAs. Herein, we have initially discussed about three major types of self-assembling nanocarriers (liposomes, polymeric nanoparticles and exosomes). Later, we have majorly reviewed recent developments in non-targeted/targeted nanocarriers for delivery of biological drugs (individual/dual) to silence the most important genes/mRNAs accountable for inducing protein abnormality. These proteins include polo-like kinase 1 (PLK1), survivin, vascular endothelial growth factor (VEGF), B-cell lymphoma/leukaemia-2 (Bcl-2) and multi-drug resistance (MDR). Besides, the consequent therapeutic effects on cancer growth, invasion and/or metastasis have also been discussed. Finally, we have comprehensively reviewed the improvements achieved in the cutting-edge cancer therapeutics while delivering siRNAs in combination with clinically approved chemotherapeutic drugs.

Well-Defined pH-Responsive Self-Assembled Block Copolymers for the Effective Codelivery of Doxorubicin and Antisense Oligonucleotide to Breast Cancer Cells

The worldwide steady increase in the number of cancer patients motivates the development of innovative drug delivery systems for combination therapy as an effective clinical modality for cancer treatment. Here, we explored a design concept based on poly(ethylene glycol)-b-poly(2-(dimethylamino)ethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate-formylbenzoic acid) [PEG-b-PDMAEMA-b-P(HEMA-FBA)] for the dual delivery of doxorubicin (DOX) and GTI2040 (an antisense oligonucleotide for ribonucleotide reductase inhibition) to MCF-7 breast cancer cells. PEG-b-PDMAEMA-b-PHEMA, the precursor copolymer, was prepared through chain extensions from a PEG-based macroinitiator via two consecutive atom transfer radical polymerization (ATRP) steps. Then, it was modified at the PHEMA block with 4-formylbenzoic acid (FBA) to install reactive aldehyde moieties. A pH-responsive polymer-drug conjugate (PDC) was obtained by conjugating DOX to the polymer structure via acid-labile imine linkages, and subsequently self-assembled in an aqueous solution to form DOX-loaded self-assembled nanoparticles (DOX-SAN) with a positively charged shell. DOX-SAN condensed readily with negatively charged GTI2040 to form GTI2040/DOX-SAN nanocomplexes. Gel-retardation assay confirmed the affinity between GTI2040 and DOX-SAN. The GTI2040/DOX-SAN nanocomplex at N/P ratio of 30 exhibited a volume-average hydrodynamic size of 136.4 nm and a zeta potential of 21.0 mV. The pH-sensitivity of DOX-SAN was confirmed by the DOX release study based on the significant cumulative DOX release at pH 5.5 relative to pH 7.4. Cellular uptake study demonstrated favorable accumulation of GTI2040/DOX-SAN inside MCF-7 cells compared with free GTI2040/DOX. In vitro cytotoxicity study indicated higher therapeutic efficacy of GTI2040/DOX-SAN relative to DOX-SAN alone because of the downregulation of the R2 protein of ribonucleotide reductase. These outcomes suggest that the self-assembled pH-responsive triblock copolymer is a promising platform for combination therapy, which may be more effective in combating cancer than individual therapies.

Nanoparticles-Based Strategies to Improve the Delivery of Therapeutic Small Interfering RNA in Precision Oncology

Small interfering RNA (siRNA) can selectively suppress the expression of disease-causing genes, holding great promise in the treatment of human diseases, including malignant cancers. In recent years, with the development of chemical modification and delivery technology, several siRNA-based therapeutic drugs have been approved for the treatment of non-cancerous liver diseases. Nevertheless, the clinical development of siRNA-based cancer therapeutics remains a major translational challenge. The main obstacles of siRNA therapeutics in oncology include both extracellular and intracellular barriers, such as instability under physiological conditions, insufficient tumor targeting and permeability (particularly for extrahepatic tumors), off-target effects, poor cellular uptake, and inefficient endosomal escape. The development of clinically suitable and effective siRNA delivery systems is expected to overcome these challenges. Herein, we mainly discuss recent strategies to improve the delivery and efficacy of therapeutic siRNA in cancer, including the application of non-viral nanoparticle-based carriers, the selection of target genes for therapeutic silencing, and the combination with other therapeutic modalities. In addition, we also provide an outlook on the ongoing challenges and possible future developments of siRNA-based cancer therapeutics during clinical translation.

Chemosensitizing effect and mechanism of imperatorin on the anti-tumor activity of doxorubicin in tumor cells and transplantation tumor model

Multidrug resistance of tumors has been a severe obstacle to the success of cancer chemotherapy. The study wants to investigate the reversal effects of imperatorin (IMP) on doxorubicin (DOX) resistance in K562/DOX leukemia cells, A2780/Taxol cells and in NOD/SCID mice, to explore the possible molecular mechanisms. K562/DOX and A2780/Taxol cells were treated with various concentrations of DOX and Taol with or without different concentrations of IMP, respectively. K562/DOX xenograft model was used to assess anti-tumor effect of IMP combined with DOX. MTT assay, Rhodamine 123 efflux assay, RT-PCR, and Western blot analysis were determined in vivo and in vitro. Results showed that IMP significantly enhanced the cytotoxicity of DOX and Taxol toward corresponding resistance cells. In vivo results illustrated both the tumor volume and tumor weight were significantly decreased after 2-week treatment with IMP combined with DOX compared to the DOX alone group. Western blotting and RT-PCR analyses indicated that IMP downregulated the expression of P-gp in K562/DOX xenograft tumors in NOD/SCID mice. We also evaluated glycolysis and glutamine metabolism in K562/DOX cells by measuring glucose consumption and lactate production. The results revealed that IMP could significantly reduce the glucose consumption and lactate production of K562/DOX cells. Furthermore, IMP could also remarkably repress the glutamine consumption, α-KG and ATP production of K562/DOX cells. Thus, IMP may sensitize K562/DOX cells to DOX and enhance the anti-tumor effect of DOX in K562/DOX xenograft tumors in NOD/SCID mice. IMP may be an adjuvant therapy to mitigate the multidrug resistance in leukemia chemotherapy.

Simultaneous nanocarrier-mediated delivery of siRNAs and chemotherapeutic agents in cancer therapy and diagnosis: Recent advances

Recently, investigations have revealed that RNA interference (RNAi) has a remarkable potential to decrease cancer burden by downregulating genes. Among various RNAi molecules, small interfering RNA (siRNA) has been more attractive for this goal and is able to silence a target pathological path and promote the degradation of a certain mRNA, resulting in either gain or loss of function of proteins. Moreover, therapeutic siRNAs have exhibited low side effects compared to other therapeutic molecular candidates. Nevertheless, siRNA delivery has its own limitations including quick degradation in circulation, ineffective internalization and low passive uptake by cells, possible toxicity against off-target sites, and inducing unfavorable immune responses. Therefore, delivery tools must be able to specifically direct siRNAs to their target locations without inflicting detrimental effects on other sites. To conquer the mentioned problems, nanocarrier-mediated delivery of siRNAs, using inorganic nanoparticles (NPs), polymers, and lipids, has been developed as a biocompatible delivery approach. In this review, we have discussed recent advances in the siRNA delivery methods that employ nanoparticles, lipids, and polymers, as well as the inorganic-based co-delivery systems used to deliver siRNAs and anticancer agents to target cells.

Redox/pH-Responsive 2-in-1 Chimeric Nanoparticles for the Co-Delivery of Doxorubicin and siRNA

The co-delivery of chemotherapy drugs and gene-suppressing small interfering RNA (siRNA) show promise for cancer therapy. The key to the clinical realization of this treatment model will be the development of a carrier system enabling the simultaneous delivery (“co-delivery” instead of combinatorial delivery) of chemotherapy and siRNA agents to cancer. In this study, a co-delivery system was developed from two individual components to form one integrated nanovehicle through a redox-sensitive thiol–disulfide bond for the synergistic delivery of chemotherapy and RNA silencing: doxorubicin (Dox)-loaded N,O-carboxymethyl chitosan (NOCC) complex with a thiolated hyaluronic acid (HA-SH) nanocarrier and dopamine (Dopa)-conjugated thiolated hyaluronic acid (SH-HA-Dopa)-coated calcium phosphate (CaP)-siRNA nanocarrier. The 2-in-1 chimeric nanoparticles (NPs) were structurally stable together in the storage environment and in the circulation. This smart system selectively releases Dox and siRNA into the cytosol. Furthermore, equipped with the tumor-targeting component HA, the co-delivery system shows specific targeting and high cellular uptake efficiency by receptor-mediated endocytosis. In summary, these dual-responsive (redox and pH), tumor-targeting smart 2-in-1 chimeric NPs show promise to be employed in functional co-delivery and tumor therapy.

Advances in Nanomaterials Used in Co-Delivery of siRNA and Small Molecule Drugs for Cancer Treatment

Recent advancements in nanotechnology have improved our understanding of cancer treatment and allowed the opportunity to develop novel delivery systems for cancer therapy. The biological complexities of cancer and tumour micro-environments have been shown to be highly challenging when treated with a single therapeutic approach. Current co-delivery systems which involve delivering small molecule drugs and short-interfering RNA (siRNA) have demonstrated the potential of effective suppression of tumour growth. It is worth noting that a considerable number of studies have demonstrated the synergistic effect of co-delivery systems combining siRNA and small molecule drugs, with promising results when compared to single-drug approaches. This review focuses on the recent advances in co-delivery of siRNA and small molecule drugs. The co-delivery systems are categorized based on the material classes of drug carriers. We discuss the critical properties of materials that enable co-delivery of two distinct anti-tumour agents with different properties. Key examples of co-delivery of drug/siRNA from the recent literature are highlighted and discussed. We summarize the current and emerging issues in this rapidly changing field of research in biomaterials for cancer treatments.

Nanotechnology lights up the antitumor potency by combining chemotherapy with siRNA

Nanotechnology-based combination anticancer therapy offers novel approaches to overcome the limitations of single-agent administration. The emerging siRNA technology combined with chemotherapy has shown considerable promise in anticancer therapy. There are three main challenges in the fabrication of siRNA/chemotherapeutic drug co-loaded nanovectors: adequate cargo protection, precise targeted delivery, and site-specific cargo release. This review presents a summary of the nanosystems that have recently been developed for co-delivering siRNA and chemotherapeutic drugs. Their combined therapeutic effects are also discussed.

A review of nanoparticle drug delivery systems responsive to endogenous breast cancer microenvironment

Breast cancer, as a malignant disease that seriously threatens women's health, urgently needs to be researched to develop effective and safe therapeutic drugs. Nanoparticle drug delivery systems (NDDS), provide a powerful means for drug targeting to the breast cancer, enhancing the bioavailability and reducing the adverse effects of anticancer drug. However, the breast cancer microenvironment together with heterogeneity of cancer, impedes the tumor targeting effect of NDDS. Breast cancer microenvironment, exerts endogenous stimuli, such as hypoxia, acidosis, and aberrant protease expression, shape a natural shelter for tumor growth, invasion and migration. On the basis of the ubiquitous of endogenous stimuli in the breast cancer microenvironment, researchers exploited them to design the stimuli-responsive NDDS, which response to endogenous stimulus, targeted release drug in breast cancer microenvironment. In this review, we highlighted the effect of the breast cancer microenvironment, summarized innovative NDDS responsive to the internal stimuli in the tumor microenvironment, including the material, the targeting groups, the loading drugs, targeting position and the function of stimuli-responsive nanoparticle drug delivery system. The limitations and potential applications of the stimuli-responsive nanoparticle drug delivery systems for breast cancer treatment were discussed to further the application.

Targeted Photodynamic Therapy (PDT) of Lung Cancer with Biotinylated Silicon (IV) Phthalocyanine

BACKGROUND

Lung cancer is the leading cause of cancer-associated mortality in the world. Traditional cancer therapies prolong the life expectancy of patients but often suffer from adverse reactions. Photodynamic Therapy (PDT) has been recommended as a treatment option for lung cancer in several countries, due to its non-invasive procedures, high selectivity and weak side effects.

OBJECTIVE

We have designed and synthesized a biotin receptor-targeted silicon phthalocyanine (IV) (compound 1) which showed a good therapeutic effect on biotin receptor-positive tumors. Since the overexpression of Biotin Receptor (BR) is also present in human lung cancer cells (A549), we explored the therapeutic properties of compound 1 on A549 xenograft tumor models.

METHODS

The selectivity of compound 1 toward A549 cells was studied with a fluorescence microscope and IVIS Spectrum Imaging System. The cytotoxicity was measured using the MTT assay. In vivo anti-tumor activity was investigated on the nude mice bearing A549 xenografts.

RESULTS

In vitro assays proved that compound 1 could selectively accumulate in A549 cells via the BR-mediated internalization. In vivo imaging and distribution experiments showed that compound 1 could selectively accumulate in tumor tissues of tumor-bearing mice. After 16 days of the treatment, the volumes of tumor in the PDT group were obviously smaller than that in other groups.

CONCLUSION

This study demonstrates that compound 1 is a promising photosensitizer and has broad application prospects in clinical PDT of lung cancers.

hTERT-molecular targeted therapy of ovarian cancer cells via folate-functionalized PLGA nanoparticles co-loaded with MNPs/siRNA/wortmannin

Effective telomerase-molecular targeted cancer therapy might be a promising approach for the efficient treatment of ovarian cancer. Therefore, folate-functionalized PLGA nanoparticles (NPs) were co-loaded with hTERT siRNA, Wortmannin (Wtmn), as a potent PI3K inhibitor, and magnetic nanoparticle (MNPs) as a theranostic agent to gain a multifunctional NPs for targeted drug delivery as well as molecular targeted therapy. ¹HNMR, FTIR, DLS, FE-SEM and TEM were applied to characterize the synthesized NPs. In vitro discharge pattern for siRNA and Wtmn from the dual drug-loaded NPs showed an early fast release followed by a constant release up to 200 h. According to the MRI analysis, by increasing the concentration of Fe₃O₄ in NPs, the weaker T2 signal intensity was enhanced, and a considerable contrast was detected in the MRI images. MTT assay and median-effect analysis showed that the Wtmn/siRNA-loaded MNPs-PLGA-F2 NPs display the most synergistic cytotoxicity on the SKOV-3 ovarian cancer cells. Moreover, the Wtmn/siRNA-loaded MNPs-PLGA-FA NPs could significantly reduce the expression of hTERT, AKT, and p-AKT than the single drug-encapsulated NPs (P < 0.05). Taken together, the findings showed that the multifunctional NPs relying on combinatorial therapy might have considerable potential for effective telomerase-molecular targeted therapy of ovarian cancer.

Targeting Cancer using Curcumin Encapsulated Vesicular Drug Delivery Systems

Curcumin is a major curcuminoid present in turmeric. The compound is attributed to various therapeutic properties, which include anti-oxidant, anti-inflammatory, anti-bacterial, anti-malarial, and neuroprotection. Due to its therapeutic potential, curcumin has been employed for centuries in treating different ailments. Curcumin has been investigated lately as a novel therapeutic agent in the treatment of cancer. However, the mechanisms by which curcumin exerts its cytotoxic effects on malignant cells are still not fully understood. One of the main limiting factors in the clinical use of curcumin is its poor bioavailability and rapid elimination. Advancements in drug delivery systems such as nanoparticle-based vesicular drug delivery platforms have improved several parameters, namely, drug bioavailability, solubility, stability, and controlled release properties. The use of curcumin-encapsulated niosomes to improve the physical and pharmacokinetic properties of curcumin is one such approach. This review provides an up-to-date summary of nanoparticle-based vesicular drug carriers and their therapeutic applications. Specifically, we focus on niosomes as novel drug delivery formulations and their potential in improving the delivery of challenging small molecules, including curcumin. Overall, the applications of such carriers will provide a new direction for novel pharmaceutical drug delivery, as well as for biotechnology, nutraceutical, and functional food industries.

Folate Receptor-Mediated siRNA Delivery: Recent Developments and Future Directions for RNAi Therapeutics

RNA interference (RNAi), a gene regulatory process mediated by small interfering RNAs (siRNAs), has made remarkable progress as a potential therapeutic agent against various diseases. However, RNAi is associated with fundamental challenges such as poor systemic delivery and susceptibility to the nucleases. Targeting ligand-bound delivery vehicles has improved the accumulation of drug at the target site, which has resulted in high transfection efficiency and enhanced gene silencing. Recently, folate receptor (FR)-mediated targeted delivery of siRNAs has garnered attention due to their enhanced cellular uptake and high transfection efficiency toward tumor cells. Folic acid (FA), due to its small size, low immunogenicity, high in vivo stability, and high binding affinity toward FRs, has attracted much attention for targeted siRNA delivery. FRs are overexpressed in a large number of tumors, including ovarian, breast, kidney, and lung cancer cells. In this review, we discuss recent advances in FA-mediated siRNA delivery to treat cancers and inflammatory diseases. This review summarizes various FA-conjugated nanoparticle systems reported so far in the literature, including liposome, silica, metal, graphene, dendrimers, chitosan, organic copolymers, and RNA nanoparticles. This review will help in the design and development of potential delivery vehicles for siRNA drug targeting to tumor cells using an FR-mediated approach.

Progress in Natural Compounds/siRNA Co-delivery Employing Nanovehicles for Cancer Therapy

Chemotherapy using natural compounds, such as resveratrol, curcumin, paclitaxel, docetaxel, etoposide, doxorubicin, and camptothecin, is of importance in cancer therapy because of the outstanding therapeutic activity and multitargeting capability of these compounds. However, poor solubility and bioavailability of natural compounds have limited their efficacy in cancer therapy. To circumvent this hurdle, nanocarriers have been designed to improve the antitumor activity of the aforementioned compounds. Nevertheless, cancer treatment is still a challenge, demanding novel strategies. It is well-known that a combination of natural products and gene therapy is advantageous over monotherapy. Delivery of multiple therapeutic agents/small interfering RNA (siRNA) as a potent gene-editing tool in cancer therapy can maximize the synergistic effects against tumor cells. In the present review, co-delivery of natural compounds/siRNA using nanovehicles are highlighted to provide a backdrop for future research.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

Phenylboronic acid-functionalized F127-oligochitosan conjugate micelles for doxorubicin encapsulation

Doxorubicin shows good anticancer activity, but poor pharmacokinetic property and high organ toxicity restrict its clinical application. The synthesized phenylboronic acid-modified F127-chitosan conjugate was used to prepare doxorubicin-loaded micelles through dialysis method. The physicochemical properties of the doxorubicin-loaded micelles were characterized. These micelles were further evaluated for in vitro release/cytotoxicity, in vivo activity/biosafety, and pharmacokinetic studies. in vitro release experiment demonstrated that the release of doxorubicin from drug-loaded micelles was pH-dependent. in vitro cytotoxic study showed that the introduction of phenylboronic acid resulted in lower IC₅₀ against B16 cells than that in non-modified F127-chitosan micelles group, and the doxorubicin-loaded micelles displayed lower in vitro activity against B16, A549, and HT-29 cells than free doxorubicin did. However, in vivo experiments confirmed that the doxorubicin-loaded micelles were safe for mouse main organs, obviously improved pharmacokinetic parameters of doxorubicin in rat and achieved comparable inhibition of tumor growth with no animal death in B16-bearing mice models throughout the experiment when compared with free doxorubicin. The phenylboronic acid-sialic acid interaction and pH-sensitive drug release might play important roles in increased tumor targeting and therapeutic effect of the doxorubicin-loaded micelles.

Redox- and MMP-2-sensitive drug delivery nanoparticles based on gelatin and albumin for tumor targeted delivery of paclitaxel

Tumor-responsive nanocarriers are highly valuable and demanded for smart anticancer drug delivery, where a quick release of chemotherapeutic drugs in tumors is preferred. Herein, a redox and MMP-2 sensitive nanoparticle has been designed for targeted delivery of PTX. Bovine serum albumin as a targeting ligand and gelatin as a hydrophilic carrier and MMP-2 sensitive reagent were used to construct the nanoparticles. Disulfide containing prodrug (PTX-SS-COOH) was grafted to the sulfhydryl modified gelatin to form the redox sensitive amphiphilic polymer. The nanoparticles were formed by self-assembly of amphiphilic polymer and BSA covering. Furthermore the modified sulfhydryl group on the gelatin can form a disulfide bond by self-crosslinking in the air, which endows the nanoparticle with a stable structure. The nanoparticle was sensitive to changes in MMP-2 concentration and redox potential, resulting in multiple responsive drug delivery to the tumor microenvironment. We further verified the anticancer effect of the nanoparticles both in vitro and in vivo, the nanoparticle (BSA/Gel-SS-PTX/PTX-SS-COOH NPs) demonstrated an excellent anticancer efficiency.

Co-delivery of curcumin and Bcl-2 siRNA by PAMAM dendrimers for enhancement of the therapeutic efficacy in HeLa cancer cells

Co-delivery of therapeutic agents and small interfering RNA (siRNA) can be achieved by a suitable nanovehicle. In this work, the solubility and bioavailability of curcumin (Cur) were enhanced by entrapment in a polyamidoamine (PAMAM) dendrimer, and a polyplex was formed by grafting Bcl-2 siRNA onto the surface amine groups to produce PAMAM-Cur/Bcl-2 siRNA nanoparticles (NPs). The synthesized polyplex NPs had a particle size of ∼180 nm, and high Cur loading content of ∼82 wt%. Moreover, the PAMAM-Cur/Bcl-2 siRNA NPs showed more effective cellular uptake, and higher inhibition of tumor cell proliferation compared to PAMAM-Cur nanoformulation and free Cur, due to the combined effect of co-delivery of Cur and Bcl-2 siRNA. The newly described PAMAM-Cur/Bcl-2 siRNA polyplex NPs could be a promising co-delivery nanovehicle.

Codelivery of DOX and siRNA by folate-biotin-quaternized starch nanoparticles for promoting synergistic suppression of human lung cancer cells

In this paper, the self-assembled folate-biotin-quaternized starch nanoparticles (FBqS NPs) were used as carrier system of doxorubicin (DOX) and siRNAIGF1R for the codelivery of both into human lung adenocarcinoma cell lines (A549 cells) in vitro. The cytotoxicity, targeted ligand competition, cell proliferation inhibition, cellular uptake, endocytosis mechanism and target protein suppression of drug-loaded FBqS NPs were evaluated in detail. Compared with several other drug formulations under same condition, siRNAIGF1R/DOX/FBqS NPs exhibited the greatest cytotoxicity to A549 cells and the cytotoxicity was competitively inhibited by free folate in dose-dependent manner. The A549 cells treated by siRNAIGF1R/DOX/FBqS NPs showed the lowest cell proliferation capacity. The energy-dependent clathrin- and caveolae-mediated endocytosis might be the primary cellular uptake mechanism of drug-loaded FBqS NPs. The expression of IGF1R protein in A549 cells treated by siRNAIGF1R/FBqS NPs declined dramatically. So the FBqS NPs were expected as the co-carrier system of chemotherapeutants and siRNAs for future clinical application.

Multifunctional PEG-b-polypeptide-decorated gold nanorod for targeted combined chemo-photothermal therapy of breast cancer

The combination of chemotherapy and photothermal therapy is acknowledged as one of the most promising approaches in cancer treatment. Targeted delivery and controlled drug release are two important factors for combined chemo-photothermal therapy. In this study, a multifunctional nanoplatform based on gold nanorod (GNR) decorated with folate-conjugated poly(ethylene glycol)-b-poly(L-γ-glutamylhydrazine) (FEGGH) containing disulfide linker and dihydroxyphenyl groups was developed for targeted combined chemo-photothermal therapy of breast cancer. FEGGH was synthesized by ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride using folate/cystamine-heterobifunctionalized poly(ethylene glycol) as an initiator, following by hydrazinolysis and carbodiimide reactions. FEGGH was decorated onto GNR through Au-catechol bonds. Chemotherapeutic drug doxorubicin (DOX) was loaded onto the nanoplatform through pH-sensitive hydrazone linkage, obtaining final product FEGGH^DOX-GNR. The DOX-loaded nanoplatform displayed excellent photostability and reduction/pH dual-responsive drug release behavior. Cytological studies demonstrated the effective internalization of FEGGH^DOX-GNR into MCF-7 cells via folate-mediated endocytosis and additive therapeutic effect of combined photothermal-chemotherapy. These results indicate that our nanoplatform may be a promising strategy for targeted combined chemo-photothermal therapy of breast cancer.

Bacterial magnetosomes-based nanocarriers for co-delivery of cancer therapeutics in vitro

In recent times, co-delivery of therapeutics has emerged as a promising strategy for treating dreadful diseases such as cancer.

MATERIALS AND METHODS

In this study, we developed a novel nanocarrier based on bacterial magnetosomes (BMs) that co-loaded with siRNA and doxorubicin (DOX) using polyethyleneimine (PEI) as a cross-linker (BMs/DP/siRNA). The delivery efficiency of siRNA as well as the pH-responsive release of DOX, and synergistic efficacy of these therapeutics in vitro were systematically investigated.

RESULTS

The structure of DOX-PEI (DP) conjugates that synthesized via hydrazone bond formation was confirmed by 1H nuclear magnetic resonance (NMR). The in vitro release experiments showed that the DP conjugate (DOX-loading efficiency - 5.77%±0.08%) exhibited the long-term release behavior. Furthermore, the optimal BMs/DP/siRNA particle size of 107.2 nm and the zeta potential value of 31.1±1.0 mV facilitated enhanced cellular internalization efficiency. Moreover, the agarose gel electrophoresis showed that the co-delivery system could protect siRNA from degradation in serum and RNase A. In addition, the cytotoxicity assay showed that BMs/DP/siRNA could achieve an excellent synergistic effect compared to that of siRNA delivery alone. The acridine orange (AO)/ethidium bromide (EB) double staining assay also showed that BMs/DP/siRNA complex could induce cells in a stage of late apoptosis and nanocomplex located in the proximity of the nucleus.

CONCLUSION

The combination of gene and chemotherapeutic drug using BMs is highly efficient, and the BMs/DP/siRNA would be a promising therapeutic strategy for the future therapeutics.

Synthesis, characterization and in vitro/in vivo evaluation of novel reduction-sensitive hybrid nano-echinus-like nanomedicine

To remedy the problems resulting from the usage of anti-cancer drugs in cancer chemotherapy, such as deficient drug concentration in tumour cells, low water-solubility and non-specific distribution of antitumour drugs, a kind of reduction-sensitive polymer prodrug of curcumin (Cur) containing in the nano-echinus was synthesized and designed. The nano-echinus-like nanomedicine presented synergistic effect with glycyrrhetic acid (GA) and oligomeric hyaluronic (HA) for targeting and combating HepG2 human liver cancer cell. Firstly, a kind of small molecular prodrug of Cur, dithiodipropionic acid-Cur (-SS-Cur), was chemically conjugated onto the side chain of the conjugated glycyrrhetic acid- oligomeric hyaluronic (GA-HA) to generate an amphiphilic polymeric prodrug of Cur, GA-HA-SS-Cur. The obtained GA-HA-SS-Cur prodrug and subsidiary material mPEG-DSPE could self-assemble into a sea urchin-like micelles in aqueous media and release Cur rapidly in response to glutathion (GSH). Then, Cur was loaded into the nano-echinus with a particle size of (118.1 ± 0.2 nm) and drug-loading efficiency of (8.03 ± 2.1%). The structure of GA-HA-SS-Cur was characterized by ¹H-NMR in this report. The morphology of micelles was observed with a transmission electron microscope (TEM). Subsequently, the reduction-sensitivity of the nano-echinus was confirmed by the changes in in-vitro drug release after different concentrations of GSH treatment. Besides, the cellular uptake behaviour and MTT assays of the nano-echinus were investigated, suggesting that the nano-echinus was of desirable safety and could be taken into HepG2 cells in a time-dependent manner. Later, anti-tumour efficacy in vivo revealed the effective inhibition of tumour growth.

Photo/pH-controlled host-guest interaction between an azobenzene-containing block copolymer and water-soluble pillar[6]arene as a strategy to construct the "compound vesicles" for controlled drug delivery

Herein, dual stimuli-responsive compound vesicles were constructed based on host-guest interaction between a water-soluble pillar[6]arene (WP6) and an amphiphilic azobenzene-containing block copolymers (BCP). Reversible morphological transformation between compound vesicles and solid aggregates was achieved by repeated pH- and photo-stimuli. These compound vesicles were then applied in the controlled release of water-soluble anticancer drug, doxorubicin hydrochloride (DOX · HCl). Upon external stimuli, the DOX · HCl displayed a faster release rate than that without stimuli. Moreover, the compound vesicles showed an excellent cytocompatibility toward the human breast cancer cells (Michigan Cancer Foundation-7, MCF-7), and the drug-loaded compound vesicles exhibited lower cytotoxicity than free drug. The drug-loaded compound vesicles could be taken up by MCF-7 cells and can release the DOX · HCl in cancer cells due to the acid environment, which was important for applications in the therapy of cancers as a controlled-release drug carrier.

Targeted delivery of siRNA using RGDfC-conjugated functionalized selenium nanoparticles for anticancer therapy

Lack of biocompatible and effective delivery carriers is a significant shortcoming for siRNA-mediated cancer therapy. To overcome these limitations, selenium nanoparticles (SeNPs) have been proposed for siRNA transfection vehicles. In this study, we synthesized novel RGDfC peptide modified selenium nanoparticles (RGDfC-SeNPs) as a gene vehicle, which was expected to improve the tumor-targeted delivery activity. RGDfC-SeNPs were compacted with siRNAs (anti-Oct4) by electrostatic interaction, which was capable of protecting siRNA from degradation. RGDfC-SeNPs exhibited excellent ability to deliver siRNA into HepG2 cells. siRNA transfection assay showed that RGDfC-SeNPs presented a higher gene silencing efficacy than conventional lipofectamine 2000. The cytotoxicity of RGDfC-SeNPs/siRNA on normal cells was lower than that on tumor cells, indicating that RGDfC-SeNPs/siRNA exhibited selectivity between normal and cancer cells. Additionally, Oct4 knockdown mediated by the selenium nanoparticle transfection arrested HepG2 cells mainly at the G2/M phase and significantly induced HepG2 cell apoptosis. Western blotting results showed that RGDfC-SeNPs/siRNA might trigger Wnt/β-catenin signaling, and further activate a BCL-2 apoptosis-related signaling pathway to advance HepG2 cell apoptosis. In vivo biodistribution experiments indicated that RGDfC-SeNPs/siRNA nanoparticles were specifically targeted to the HepG2 tumors. Most importantly, RGDfC-SeNPs/siRNA inhibited tumor growth significantly and induced HepG2 cell apoptosis via silencing the Oct4 gene. In addition, the results of H&E staining demonstrated that RGDfC-SeNPs/siRNA had negligible toxicity on the major organs of mice. In a word, this study provides a novel strategy for the design of biocompatible and effective siRNA delivery vehicles in cancer therapy.