Nanomaterials and autophagy: new insights in cancer treatment

Nanomedicine in Bladder Cancer Therapy

Bladder cancer (BC) is one of the most common malignant neoplasms of the genitourinary system. Traditional BC therapies include chemotherapy, targeted therapy, and immunotherapy. However, limitations such as lack of specificity, cytotoxicity, and multidrug resistance pose serious challenges to the benefits of BC therapies. Consequently, current studies focus on the search for new therapeutic solutions. In recent years, there has been a growing interest in using nanotechnology in the treatment of both non-invasive (NMIBC) and invasive bladder cancer (MIBC). Nanotechnology is based on the use of both organic molecules (chitosan, liposomes) and inorganic molecules (superparamagnetic iron oxide nanoparticles) as carriers of active substances. The main aim of such molecules is the targeted transport and prolonged retention of the drug in the target tissue, which increases the therapeutic efficacy of the active substance. This review discusses the numerous types of nanoparticles (including chitosan, polymeric nanoparticles, liposomes, and protein nanoparticles), targeting mechanisms, and approved nanotherapeutics with oncological implications in cancer treatment. We also present nanoformulation applications in phototherapy, gene therapy, and immunotherapy. Moreover, we summarise the current perspectives, advantages, and challenges in clinical translation.

Cyclodextrin Nanosponges: A Revolutionary Drug Delivery Strategy

Nanosponges are porous solid cross-linked polymeric nanostructures. This study focuses on cyclodextrin-based nanosponges. Nanosponges based on cyclodextrin can form interactions with various lipophilic or hydrophilic compounds. The release of the entrapped molecules can be altered by altering the structure to obtain either a longer or faster release kinetics. The nanosponges might increase the aqueous solubility of weakly water-soluble compounds, develop long-lasting delivery systems, or construct novel drug carriers for nanomedicine. CD-NS (cyclodextrin-based nanosponges) are evolving as flexible and promising nanomaterials for medication administration, sensing, and environmental cleanup. CD-NS are three-dimensional porous structures of cyclodextrin molecules cross-linked by a suitable polymeric network, resulting in a large surface area. This overview covers CD-NS synthesis methods and applications.

Controlling Polymersome Size through Microfluidic-Assisted Self-Assembly: Enabling 'Ready to Use' formulations for biological applications

The self-assembly of poly(ethylene glycol)-block-poly(trimethylene carbonate) PEG-b-PTMC copolymers into vesicles, also referred as polymersomes, was evaluated by solvent displacement using microfluidic systems. Two microfluidic chips with different flow regimes (micromixer and Herringbone) were used and the impact of process conditions on vesicle formation was evaluated. As polymersomes are sensitive to osmotic variations, their preparation under conditions allowing their direct use in biological medium is of major importance. We therefore developed a solvent exchange approach from DMSO (Dimethylsulfoxide) to aqueous media with an osmolarity of 300 mOsm.L^-1, allowing their direct use for biological evaluation. We evidenced that the organic/aqueous solvent ratio does not impact vesicle size, but the total flow rate and copolymer concentration have been observed to influence the size of polymersomes. Finally, nanoparticles with diameters ranging from 76 nm to 224 nm were confirmed to be vesicles through the use of multi-angle light scattering in combination with cryo-TEM (Cryo-Transmission Electron Microscopy) characterization.

Autophagy induced macrophages by α-alumina(α-AL2O3) conjugated cysteine peptidase, enhances the cytotoxic activity of CD8+ T lymphocytes against Leishmania major

Introduction

Induction of a protective immune response against Leishmania major requires the activation of both TH1 and CD8+ T lymphocytes. Because L. major is an intra-phagosomal parasite, its antigens do not have access to MHC-I. The present study aimed to evaluate the effect of cysteine peptidase A (CPA)/cysteine peptidase B (CPB) conjugated to α-AL2O3 on autophagy induction in L. major infected macrophages and subsequent activation of cytotoxic CD8+ T lymphocytes.

Methods

Recombinant CPA and CPB of L. major were produced in expression vectors and purified. Aldehyde functionalized α-AL2O3 were conjugated to hydrazine-modified CPA/CPB by a chemical bond was confirmed by Fourier-transform infrared spectroscopy (FTIR). The High efficient internalization of α-AL2O3 conjugated CPA/CPB to macrophages was confirmed using a fluorescence microscope and flowcytometry. Induction of the acidic autophagosome and LC3 conversion in macrophages was determined by acridine orange (AO) staining and western blot. Autophagy-activated macrophages were used for CD8+ T cell priming. Cytotoxic activity of the primed CD8+ T cell against L. major infected macrophages was measured using apoptosis assay.

Results

α-AL2O3 conjugated CPA/CPB enhances macrophages antigen uptake and increases acidic vacuole formation and LC-3I to LC-3II conversion. Co-culture of autophagy-activated macrophages with CD8+ T cells augmented CD8+ T cells priming and proliferation more than in other study groups. These primed CD8+ T cells induce significant apoptotic death of L. major infected macrophages compared with non-primed CD8+ T cells.

Conclusion

α-AL2O3 nanoparticles enhance the cross-presentation of L. major antigens to CD8+ T cells by inducing autophagy. This finding supports the positive role of autophagy and encourages the use of α-AL2O3 in vaccine design.

Benzylisoquinoline Alkaloids from the Stems of Limacia scandens and Their Potential as Autophagy Inhibitors

Limacia scandens is traditionally used to treat depression and affective disorders in Malaysia. The chemical compositions have been reported to include bisbenzylisoquinoline and aporphine-type alkaloids in the genus Limacia Lour., but studies on the components of L. scandens have rarely been reported. Therefore, this study was conducted to determine new benzylisoquinoline alkaloid derivatives with autophagy regulation activity from this plant. Bioactivity-guided isolation was applied to various column chromatography methods using RP-18, Sephadex LH-20 open column chromatography, and preparative HPLC. The chemical structures of the isolated compounds were elucidated through spectroscopic data analysis, including NMR, HR-ESI-MS, and ECD data. In addition, isolated compounds were tested for autophagy-regulating activity in HEK293 cells expressing GFP-L3. Three new dimeric benzylisoquinoline alkaloids (1−3), one new 4-hydroxybenzoic acid-conjugated benzylisoquinoline alkaloid (4), and six known compounds (5−10) were isolated from the stems of L. scandens. All compounds (1–10) were screened for autophagy regulation in HEK293 cells stably expressing the GFP-LC3 plasmid. Among the isolated compounds, 1, 2, and 4 showed autophagic regulation activity that blocked the process of combining autophagosomes and lysosomes. They also inhibit the protein degradation process from the autolysosome as inhibitors of autophagy. Novel benzylisoquinoline alkaloids from L. scandens showed potent potency for the inhibition of autophagic flux. This study provides potential candidates for developing natural autophagy inhibitors for disease prevention and treatment.

Pro-inflammatory effects of silver nanoparticles in the intestine

Nanotechnology is a promising technology of the twenty-first century, being a rapidly evolving field of research and industrial innovation widely applied in our everyday life. Silver nanoparticles (AgNP) are considered the most commercialized nanosystems worldwide, being applied in diverse sectors, from medicine to the food industry. Considering their unique physical, chemical and biological properties, AgNP have gained access into our daily life, with an exponential use in food industry, leading to an increased inevitable human oral exposure. With the growing use of AgNP, several concerns have been raised, in recent years, about their potential hazards to human health, more precisely their pro-inflammatory effects within the gastrointestinal system. Therefore a review of the literature has been undertaken to understand the pro-inflammatory potential of AgNP, after human oral exposure, in the intestine. Despite the paucity of information reported in the literature about this issue, existing studies indicate that AgNP exert a pro-inflammatory action, through generation of oxidative stress, accompanied by mitochondrial dysfunction, interference with transcription factors and production of cytokines. However, further studies are needed to elucidate the mechanistic pathways and molecular targets involved in the intestinal pro-inflammatory effects of AgNP.

Cholesterol-Based Nanovesicles Enhance the In Vitro Cytotoxicity, Ex Vivo Intestinal Absorption, and In Vivo Bioavailability of Flutamide

Critical adverse effects and frequent administration, three times per day, limit the use of flutamide (FLT) as a chemotherapeutic agent in the treatment of prostate cancer. Therefore, our research aimed to develop new cholesterol-based nanovesicles for delivering FLT to malignant cells in an endeavor to maximize its therapeutic efficacy and minimize undesired adverse effects. Draper–Lin small composite design was used to optimize the critical quality attributes of FLT-loaded niosomes and ensure the desired product quality. The influence of the selected four independent variables on mean particle size (Y₁), zeta potential (Y₂), drug entrapment efficiency (Y₃), and the cumulative drug release after 24 h (Y₄) was examined. The optimized nanovesicles were assessed for their in vitro cytotoxicity, ex-vivo absorption via freshly excised rabbit intestine as well as in vivo pharmacokinetics on male rats. TEM confirmed nanovescicles’ spherical shape with bilayer structure. Values of dependent variables were 748.6 nm, −48.60 mV, 72.8% and 72.2% for Y₁, Y₂, Y₃ and Y₄, respectively. The optimized FLT-loaded niosomes exerted high cytotoxic efficacy against human prostate cancer cell line (PC-3) with an IC₅₀ value of 0.64 ± 0.04 µg/mL whilst, it was 1.88 ± 0.16 µg/mL for free FLT. Moreover, the IC₅₀ values on breast cancer cell line (MCF-7) were 0.27 ± 0.07 µg/mL and 4.07 ± 0.74 µg/mL for FLT-loaded niosomes and free FLT, respectively. The permeation of the optimized FLT-loaded niosomes through the rabbit intestine showed an enhancement ratio of about 1.5 times that of the free FLT suspension. In vivo pharmacokinetic study displayed an improvement in oral bioavailability of the optimized niosomal formulation with AUC and C_max values of 741.583 ± 33.557 μg/mL × min and 6.950 ± 0.45 μg/mL compared to 364.536 ± 45.215 μg/mL × min and 2.650 ± 0.55 μg/mL for the oral FLT suspension. With these promising findings, we conclude that encapsulation of FLT in cholesterol-loaded nanovesicles enhanced its anticancer activity and oral bioavailability which endorse its use in the management of prostate cancer.

Eugenol-Induced Autophagy and Apoptosis in Breast Cancer Cells via PI3K/AKT/FOXO3a Pathway Inhibition

The use of natural compounds is promising in approaches to prevent and treat cancer. The long-term application of most currently employed chemotherapy techniques has toxic side effects. Eugenol, a phenolic phytochemical extracted from certain essential oils, has an anti-cancer effect. The modulation of autophagy can promote either the survival or apoptosis of cancer cells. Triple-negative (MDA-MB-231) and HER2 positive (SK-BR-3) breast cancer cell lines were treated with different doses of eugenol. Apoptosis was detected by a flow-cytometry technique, while autophagy was detected by acridine orange. Real-time PCR and Western blot assays were applied to investigate the effect of eugenol on the gene and protein expression levels of autophagy and apoptotic genes. Treating cells with different concentrations of eugenol significantly inhibited cell proliferation. The protein levels of AKT serine/threonine kinase 1 (AKT), forkhead box O3 (FOXO3a), cyclin dependent kinase inhibitor 1A (p21), cyclin-dependent kinase inhibitor (p27), and Caspase-3 and -9 increased significantly in Eugenol-treated cells. Eugenol also induced autophagy by upregulating the expression levels of microtubule-associated protein 1 light chain 3 (LC3) and downregulating the expression of nucleoporin 62 (NU p62). Eugenol is a promising natural anti-cancer agent against triple-negative and HER2-positive breast cancer. It appears to work by targeting the caspase pathway and by inducing autophagic cell death.

Nanoemulsions: A Review on the Conceptualization of Treatment for Psoriasis Using a 'Green' Surfactant with Low-Energy Emulsification Method

Psoriasis is a skin disease that is not lethal and does not spread through bodily contact. However, this seemingly harmless condition can lead to a loss of confidence and social stigmatization due to a persons' flawed appearance. The conventional methods of psoriasis treatment include taking in systemic drugs to inhibit immunoresponses within the body or applying topical drugs onto the surface of the skin to inhibit cell proliferation. Topical methods are favored as they pose lesser side effects compared to the systemic methods. However, the side effects from systemic drugs and low bioavailability of topical drugs are the limitations to the treatment. The use of nanotechnology in this field has enhanced drug loading capacity and reduced dosage size. In this review, biosurfactants were introduced as a 'greener' alternative to their synthetic counterparts. Glycolipid biosurfactants are specifically suited for anti-psoriatic application due to their characteristic skin-enhancing qualities. The selection of a suitable oil phase can also contribute to the anti-psoriatic effect as some oils have skin-healing properties. The review covers the pathogenic pathway of psoriasis, conventional treatments, and prospective ingredients to be used as components in the nanoemulsion formulation. Furthermore, an insight into the state-of-the-art methods used in formulating nanoemulsions and their progression to low-energy methods are also elaborated in detail.

CLEAR - Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

Identification of Three Autophagy-Related Long Non-Coding RNAs as a Novel Head and Neck Squamous Cell Carcinoma Prognostic Signature

Head and neck squamous cell carcinoma (HNSCC) has a poor prognosis. Considerable evidence indicates that autophagy and non-coding RNA play essential roles in the biological processes involved in cancers, but associations between autophagy-related long non-coding RNAs (lncRNAs) and HNSCC remain unclear. In the present study, HNSCC RNA sequences and autophagy-related gene data were extracted from The Cancer Genome Atlas database and the Human Autophagy Database. A total of 1,153 autophagy-related lncRNAs were selected via calculating Pearson’s correlation coefficient. Three prognosis-related autophagy lncRNAs were identified via univariate Cox regression, least absolute shrinkage and selection operator analysis, and multivariate Cox regression analysis. We also constructed a prognostic model based on these autophagy-related lncRNAs and evaluated its ability to accurately and independently predict the prognosis of HNSCC patients. The area under the curve (AUC) was 0.864 (3-year) and 0.836 (5-year), and our model can independently predict the prognosis of HNSCC. The prognostic value of the three autophagy lncRNAs was confirmed via analysis of samples from five databases. To further identify the functions of the three lncRNAs, a co-expression network was constructed and pathway analysis was performed. In that analysis the lncRNAs were correlated with 189 related genes and 20 autophagy-related genes, and these lncRNAs mainly involved homologous recombination, the Fanconi anemia pathway, the autophagy-related pathway, and immune-related pathways. In addition, we validated the expression levels of three lncRNAs and autophagy markers (ATG12, BECN1, and MAP1LC3B) based on TIMER, Oncomine, and HPA database analysis. Our results indicated that TTTY15 was increased in HPV positive and HPV negative HNSCC patients, and three autophagy markers were up-regulated in all HNSCCC patients. Lastly, association between three lncRNAs and autophagy markers was performed, and our results showed that TTTY15 and MIF-AS1 were associated with autophagy markers. Collectively, these results suggested that three autophagy-related lncRNAs have prognostic value in HNSCC patients.

Cyclodextrin nanosponge for the GSH-mediated delivery of Resveratrol in human cancer cells

Smart drug delivery systems are required for the site-specific drug targeting to enhance the therapeutic efficiency of a drug. Resveratrol (RV) is a polyphenolic compound with anti-cancer activity. However, its poor aqueous solubility and non-selectivity are the major challenges for its employment in cancer therapy. In this work, we present the synthesis of RV-loaded glutathione responsive cyclodextrin nanosponges (RV-GSH-NSs) to improve the therapeutic efficiency and selective delivery of RV. The drug loading and encapsulation efficiency were 16.12% and 80.64%, respectively. The in vitro release profile confirmed that RV release was enhanced in response to external glutathione (GSH). Nude NSs were not toxic per se to human fibroblasts when administered for up to 72 h at the highest dose. Cell internalization studies confirmed that RV-GSH-NSs were preferentially up-taken by tumor cells compared to non-tumorigenic cells. Accordingly, RV showed selective toxicity to cancer cells compared to normal cells. GSH depletion by buthionine sulfoximine, a potent inhibitor of its synthesis, reflected in a significant decrease of the NSs accumulation, and consequently resulted in a drastic reduction of RV-mediated toxic effects in cancer cells. These findings demonstrate that GSH- responsive NSs represent an effective delivery system for targeting cancer cells by harnessing the differential tumor characteristics in terms of redox status in parallel with the limitation of side effects toward normal cells.

Novel therapeutic regimens for urethane-induced early lung cancer in rats: Combined cisplatin nanoparticles with vitamin-D3

Lung cancer remains incurable; therefore, novel therapeutical approaches are of great demand. This study was designed to investigate the effectiveness of cisplatin nanoparticles combined with vitamin-D₃ on urethane-induced early lung cancer in rats and to clarify the underlying signaling mechanisms. Early lung cancer was induced in male Wistar rats by urethane. Rats were divided into six groups: I-control, II-cancer untreated, III-cancer + free cisplatin, IV-cancer + cisplatin nanoparticles, V-cancer + free cisplatin + vitamin-D₃ , VI-cancer + cisplatin nanoparticles + vitamin-D₃ . Inflammation, proliferation, and apoptosis were evaluated together with the levels of tumor marker CK-19 along with histological assessment. Treatment of lung cancer with either free or nanoparticles of cisplatin alone demonstrated significant suppression in the expression of inflammatory, anti-apoptotic and tumor markers compared to rats with lung cancer. Moreover, vitamin-D₃ supplementation with either cisplatin forms lead to a further decrease of all markers, markedly with cisplatin nanoparticles. The present study shows the synergistic effect of cisplatin-nanoparticles combined with vitamin-D₃ as a new therapy regimen against lung cancer. Further studies with larger sample sizes and longer duration are needed to confirm these results.

Carbon Nanospheres Exert Antitumor Effects Associated with Downregulation of 4E-BP1 Expression on Prostate Cancer

Introduction

Although carbon nanospheres (CNPs) are promising nanomaterials in cancer treatment, how they affect prostate cancer (PCa) remains unclear.

Methods

In this study, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were used to confirm the successful synthesis of CNPs. CCK-8, flow cytometry, Transwell, wound healing, Western blot and immunohistochemistry (IHC) assays were performed to evaluate the antitumor effect of CNPs toward the two kinds of prostate cancer cell lines PC3 and DU145.

Results

Our results showed that CNPs inhibited cell growth, invasion, and migration and induced apoptosis and autophagy in PCa cells. Multifactor detection of a single Akt phosphorylation pathway and Western blot results suggested the suppression of 4E-BP1 in PCa cells after incubation with CNPs. The results from animal experiments also suggested the antitumor effect of CNPs and reduced 4E-BP1 expression in PCa tissue samples from BALB/c nude mice administered a local subcutaneous injection of CNPs.

The Effect of the Chorion on Size-Dependent Acute Toxicity and Underlying Mechanisms of Amine-Modified Silver Nanoparticles in Zebrafish Embryos

As the worldwide application of nanomaterials in commercial products increases every year, various nanoparticles from industry might present possible risks to aquatic systems and human health. Presently, there are many unknowns about the toxic effects of nanomaterials, especially because the unique physicochemical properties of nanomaterials affect functional and toxic reactions. In our research, we sought to identify the targets and mechanisms for the deleterious effects of two different sizes (~10 and ~50 nm) of amine-modified silver nanoparticles (AgNPs) in a zebrafish embryo model. Fluorescently labeled AgNPs were taken up into embryos via the chorion. The larger-sized AgNPs (LAS) were distributed throughout developing zebrafish tissues to a greater extent than small-sized AgNPs (SAS), which led to an enlarged chorion pore size. Time-course survivorship revealed dose- and particle size-responsive effects, and consequently triggered abnormal phenotypes. LAS exposure led to lysosomal activity changes and higher number of apoptotic cells distributed among the developmental organs of the zebrafish embryo. Overall, AgNPs of ~50 nm in diameter exhibited different behavior from the ~10-nm-diameter AgNPs. The specific toxic effects caused by these differences in nanoscale particle size may result from the different mechanisms, which remain to be further investigated in a follow-up study.

Targeting Cancer Resistance via Multifunctional Gold Nanoparticles

Resistance to chemotherapy is a major problem facing current cancer therapy, which is continuously aiming at the development of new compounds that are capable of tackling tumors that developed resistance toward common chemotherapeutic agents, such as doxorubicin (DOX). Alongside the development of new generations of compounds, nanotechnology-based delivery strategies can significantly improve the in vivo drug stability and target specificity for overcoming drug resistance. In this study, multifunctional gold nanoparticles (AuNP) have been used as a nanoplatform for the targeted delivery of an original anticancer agent, a Zn(II) coordination compound [Zn(DION)2]Cl2 (ZnD), toward better efficacy against DOX-resistant colorectal carcinoma cells (HCT116 DR). Selective delivery of the ZnD nanosystem to cancer cells was achieved by active targeting via cetuximab, NanoZnD, which significantly inhibited cell proliferation and triggered the death of resistant tumor cells, thus improving efficacy. In vivo studies in a colorectal DOX-resistant model corroborated the capability of NanoZnD for the selective targeting of cancer cells, leading to a reduction of tumor growth without systemic toxicity. This approach highlights the potential of gold nanoformulations for the targeting of drug-resistant cancer cells.

Remote Magnetic Control of Autophagy in Mouse B-Lymphoma Cells with Iron Oxide Nanoparticles

Autophagy is the spontaneous degradation of intracellular proteins and organelles in response to nutrient deprivation. The phagocytosis of iron oxide nanoparticles (IONPs) results in intracellular degradation that can be exploited for use in cancer treatment. Non-invasive magnetic control has emerged as an important technology, with breakthroughs achieved in areas such as magneto-thermal therapy and drug delivery. This study aimed to regulate autophagy in mouse B-lymphoma cells (A20) through the incorporation of IONPs-quantum dots (QDs). We hypothesized that with the application of an external magnetic field after phagocytosis of IONPs-QDs, autophagy of intracellular IONPs-QDs could be regulated in a non-invasive manner and subsequently modulate the regulation of inflammatory responses. The potential of this approach as a cancer treatment method was explored. The application of IONPs and an external magnetic force enabled the non-invasive regulation of cell autophagy and modulation of the self-regulatory function of cells. The combination of non-invasive magnetic fields and nanotechnology could provide a new approach to cancer treatment.

Lysosome-dependent cell death and deregulated autophagy induced by amine-modified polystyrene nanoparticles

Nanoparticles (NPs) typically accumulate in lysosomes. However, their impact on lysosomal function, as well as autophagy, a lysosomal degradative pathway, is still not well known. We have previously reported in the 1321N1 cell line that amine-modified polystyrene (NH₂-PS) NPs induce apoptosis through damage initiated in the lysosomes leading ultimately to release of lysosomal content in the cytosol, followed by apoptosis. Here, by using a combination of biochemical and cell biological approaches, we have characterized in a mouse embryonic fibroblast cell line that the lysosomal alterations induced by NH₂-PS NPs is progressive, initiating from mild lysosomal membrane permeabilization (LMP), to expansion of lysosomal volume and intensive LMP before the summit of cell death. Though the cells initially seem to induce autophagy as a surviving mechanism, the damage of NH₂-PS NPs to lysosomes probably results in lysosomal dysfunctions, leading to blockage of autophagic flux at the level of lysosomes and the eventual cell death.

Cytoskeletal synchronization of CHO cells with polymer functionalized fullerene C60

Recent developments in the field of fullerene C₆₀ and its derivatives suggest its suitability in a wide range of applications ranging from photovoltaic instruments, development of solar based cells, cosmetics to enzyme inhibition treatment, and so on. These innovative applications raised possibilities of intentional or oblivious human-particle contact leading to possible deleterious effects on human health. The current study deals with the interaction of dextran functionalized fullerene C₆₀ (Dex-C₆₀) on Chinese Hamster Ovary cells. The results showed that the cell viability was not affected by Dex-C₆₀ treatment even at higher concentrations. Treatment of Dex-C₆₀ did not affect mitochondrial membrane potential and the integrity of lysosomal and cytoskeletal membrane. DNA ladder assay and nuclear staining showed that the DNA remains intact, and no fragmentation or nuclear condensation was visible. From flow cytometry analysis, the viable population of treated cells was seemed to be remaining similar to that of untreated cells. Hence, from the current result, it is concluded that Dex-C₆₀ can be a potential candidate for various biomedical applications.

Advanced microscopic evaluation of parallel type I and type II cell deaths induced by multi-functionalized gold nanocages in breast cancer

Despite aggressive surgical resections and combinatorial chemoradiations, certain highly malignant populations of tumor cells resurrect and metastasize. Mixed-grade cancer cells fail to respond to standard-of-care therapies by developing intrinsic chemoresistance and subsequently result in tumor relapse. Macroautophagy is a membrane trafficking process that underlies drug resistance and tumorigenesis in most breast cancers. Manipulating cellular homeostasis by a combinatorial nanotherapeutic model, one can evaluate the crosstalk between type I and type II cell death and decipher the fate of cancer therapy. Here, we present a multi-strategic approach in cancer targeting to mitigate the autophagic flux with subcellular toxicity via lysosome permeation, accompanied by mitochondrial perturbation and apoptosis. In this way, a nanoformulation is developed with a unique blend of a lysosomotropic agent, an immunomodulating sulfated-polysaccharide, an adjuvant chemotherapeutic agent, and a monoclonal antibody as a broad-spectrum complex for combinatorial nanotherapy of all breast cancers. To the best of our knowledge, this manuscript illustrates for the first time the applications of advanced microscopic techniques such as electron tomography, three-dimensional rendering and segmentation of subcellular interactions, and fate of the multifunctional therapeutic gold nanocages specifically targeted toward breast cancer cells.

Necrotic, apoptotic and autophagic cell fates triggered by nanoparticles

Nanomaterials have gained a rapid increase in use in a variety of applications that pertain to many aspects of human life. The majority of these innovations are centered on medical applications and a range of industrial and environmental uses ranging from electronics to environmental remediation. Despite the advantages of NPs, the knowledge of their toxicological behavior and their interactions with the cellular machinery that determines cell fate is extremely limited. This review is an attempt to summarize and increase our understanding of the mechanistic basis of nanomaterial interactions with the cellular machinery that governs cell fate and activity. We review the mechanisms of NP-induced necrosis, apoptosis and autophagy and potential implications of these pathways in nanomaterial-induced outcomes. Abbreviations: Ag, silver; CdTe, cadmium telluride; CNTs, carbon nanotubes; EC, endothelial cell; GFP, green fluorescent protein; GO, graphene oxide; GSH, glutathione; HUVECs, human umbilical vein endothelial cells; NP, nanoparticle; PEI, polyethylenimine; PVP, polyvinylpyrrolidone; QD, quantum dot; ROS, reactive oxygen species; SiO2, silicon dioxide; SPIONs, superparamagnetic iron oxide nanoparticles; SWCNT, single-walled carbon nanotubes; TiO2, titanium dioxide; USPION, ultra-small super paramagnetic iron oxide; ZnO, zinc oxide.

Autophagy-dependent toxicity of amino-functionalized nanoparticles in ovarian cancer cells

Polystyrene NH₂-NPs induce toxicity through a differential impact on autophagy machinery in ovarian cancer cells with a different genetic background.

Distinct autophagy-inducing abilities of similar-sized nanoparticles in cell culture and live C. elegans

Nanomaterial-induced autophagy has raised increasing concerns. A variety of nanomaterials, conventional or recently emerged, have the capability of inducing autophagy. As a consequence, it is becoming a popular belief that induction of autophagy is a common response of cells upon exposure to nanoscale materials. In order to clarify whether the "nanoscale" size is the determining factor for the nanomaterials to induce autophagy, we utilized in vitro cultured cells and an in vivo Caenorhabditis elegans (C. elegans) model to systemically investigate the autophagy-inducing ability of nanomaterials. We selected four types of representative nanomaterials with similar sizes, namely silicon nanoparticles (SiNPs), CdTe quantum dots (QDs), carbon dots (CDs) and gold nanoparticles (AuNPs). We demonstrated that, unlike most other nanomaterials tested, no autophagosome formation was detected in cultured cells or in live C. elegans with SiNP treatment. The expression of autophagy-related genes and the lipidation of LGG-1/LC3 in cells and C. elegans also remained unchanged after the treatment of SiNPs. In addition, the ability of the nanomaterials to induce autophagy appeared to correlate with those to incur subcellular organelle damage. Together, our studies demonstrate that SiNPs do not induce autophagy in vitro or in vivo in the selected model organisms and cell lines, thus clarifying that the "nanoscale" size is not the determining factor for the nanomaterials to induce autophagy. The results also suggest that the autophagy-inducing ability of most nanomaterials could be merely a reflection of their detrimental effect on cellular structures.

Iron oxide nanozyme suppresses intracellular Salmonella Enteritidis growth and alleviates infection in vivo

Rational:Salmonella Enteritidis (S. Enteritidis) is a globally significant zoonotic foodborne pathogen which has led to large numbers of deaths in humans and caused economic losses in animal husbandry. S. Enteritidis invades host cells and survives within the cells, causing resistance to antibiotic treatment. Effective methods of elimination and eradication of intracellular S. Enteritidis are still very limited. Here we evaluated whether a new intracellular antibacterial strategy using iron oxide nanozymes (IONzymes) exerted highly antibacterial efficacy via its intrinsic peroxidase-like activity in vitro and in vivo.Methods: The antibacterial activities of IONzymes against planktonic S. Enteritidis, intracellular S. Enteritidis in Leghorn Male Hepatoma-derived cells (LMH), and liver from specific pathogen free (SPF) chicks were investigated by spread-plate colony count method and cell viability assay. Changes in levels of microtubule-associated protein light chain 3 (LC3), a widely used marker for autophagosomes, were analyzed by immunoblotting, immunofluorescence, and electron microscopy. Reactive oxygen species (ROS) production was also assessed in vitro. High-throughput RNA sequencing was used to investigate the effects of IONzymes on liver transcriptome of S. Enteritidis-infected chicks. Results: We demonstrated that IONzymes had high biocompatibility with cultured LMH cells and chickens, which significantly inhibited intracellular S. Enteritidis survival in vitro and in vivo. In addition, co-localization of IONzymes with S. Enteritidis were observed in autophagic vacuoles of LMH cells and liver of chickens infected by S. Enteritidis, indicating that IONzymes mediated antibacterial reaction of S. Enteritidis with autophagic pathway. We found ROS level was significantly increased in infected LMH cells treated with IONzymes, which might enhance the autophagic elimination of intracellular S. Enteritidis. Moreover, orally administered IONzymes decreased S. Enteritidis organ invasion of the liver and prevented pathological lesions in a chicken-infection model. Non-target transcriptomic profiling also discovered IONzymes could change hepatic oxidation-reduction and autophagy related gene expressions in the S. Enteritidis infected chickens. Conclusion: These data suggest that IONzymes can increase ROS levels to promote the antibacterial effects of acid autophagic vacuoles, and thus suppress the establishment and survival of invading intracellular S. Enteritidis. As a result, IONzymes may be a novel alternative to current antibiotics for the control of intractable S. Enteritidis infections.

NanoTRAIL-Oncology: A Strategic Approach in Cancer Research and Therapy

TRAIL is a member of the tumor necrosis factor superfamily that can largely trigger apoptosis in a wide variety of cancer cells, but not in normal cells. However, insufficient exposure to cancer tissues or cells and drug resistance has severely impeded the clinical application of TRAIL. Recently, nanobiotechnology has brought about a revolution in advanced drug delivery for enhanced anticancer therapy using TRAIL. With the help of materials science, immunology, genetic engineering, and protein engineering, substantial progress is made by expressing fusion proteins with TRAIL, engineering TRAIL on biological membranes, and loading TRAIL into functional nanocarriers or conjugating it onto their surfaces. Thus, the nanoparticle-based TRAIL (nanoTRAIL) opens up intriguing opportunities for efficient and safe bioapplications. In this review, the mechanisms of action and biological function of TRAIL, as well as the current status of TRAIL treatment, are comprehensively discussed. The application of functional nanotechnology combined with TRAIL in cancer therapy is also discussed.

Enhancing the Therapeutic Efficacy of Tamoxifen Citrate Loaded Span-Based Nano-Vesicles on Human Breast Adenocarcinoma Cells

Serious adverse effects and low selectivity to cancer cells are the main obstacles of long term therapy with Tamoxifen (Tmx). This study aimed to develop Tmx-loaded span-based nano-vesicles for delivery to malignant tissues with maximum efficacy. The effect of three variables on vesicle size (Y₁), zeta potential (Y₂), entrapment efficiency (Y₃) and the cumulative percent release after 24 h (Y₄) were optimized using Box-Behnken design. The optimized formula was prepared and tested for its stability in different storage conditions. The observed values for the optimized formula were 310.2 nm, - 42.09 mV, 75.45 and 71.70% for Y₁, Y₂, Y₃, and Y₄, respectively. The examination using electron microscopy confirmed the formation of rounded vesicles with distinctive bilayer structure. Moreover, the cytotoxic activity of the optimized formula on both breast cancer cells (MCF-7) and normal cells (BHK) showed enhanced selectivity (9.4 folds) on cancerous cells with IC₅₀ values 4.7 ± 1.5 and 44.3 ± 1.3 μg/ml on cancer and normal cells, respectively. While, free Tmx exhibited lower selectivity (2.5 folds) than optimized nano-vesicles on cancer cells with IC₅₀ values of 9.0 ± 1.1 μg/ml and 22.5 ± 5.3 μg/ml on MCF-7 and BHK cells, respectively. The promising prepared vesicular system, with greater efficacy and selectivity, provides a marvelous tool to overcome breast cancer treatment challenges.

The impact of immunotoxicity in evaluation of the nanomaterials safety

Nanomedicinal products (NMPs), due to their unique properties, are extensively investigated for their biomedical and pharmaceutical applications. Apart from being carriers of certain drugs, nanoparticles can also interact with both the innate and adaptive immune systems, thus eliciting immune responses. Following administration, their discrete physicochemical properties make each NMP act differently in the organism. Actually, the toxic effects of NMPs, in terms of specific end points, do not necessarily depend on the specific group or structural type of the particle. Furthermore, the nanoformulation may change the pharmacokinetic/toxicokinetic profile of the drug. Unveiling the structure–activity relationship of NMPs would help to clarify their immunomodulatory effects. Therefore, in addition to the current regulatory immunotoxicity testing strategies, development and regulatory approval of nano-sized pharmaceuticals still need to be discussed in order to identify potential gaps in the safety assessment.

Modulation of quantum dots and clearance of Helicobacter pylori with synergy of cell autophagy

Helicobacter pylori (Hp) is one type of Gram-negative pathogenic bacterium that colonizes and causes a wide range of gastric diseases. Once Hp penetrates into cells, the currently recognized triple or quadruple therapy often loses effectiveness. Recent evidence suggests that autophagy is closely associated with Hp infection, and can play an important role in the eradication of Hp. More importantly, certain types of quantum dots (QDs) can induce and modulate cellular autophagy, and can be developed into conjugates making QDs potential candidates as new anti-Hp agents.

Silver nanoparticles of different sizes induce a mixed type of programmed cell death in human pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma, with the high resistance to chemotherapeutic agents, remains the fourth leading cause of cancer-death in the world. Due to the wide range of biological activity and unique properties, silver nanoparticles (AgNPs) are indicated as agents with potential to overcome barriers involved in chemotherapy failure. Therefore, in our study we decided to assess the ability of AgNPs to kill pancreatic cancer cells, and then to identify the molecular mechanism underlying this effect. Moreover, we evaluated the cytotoxicity of AgNPs against non-tumor cell of the same tissue (hTERT-HPNE cells) for comparison. Our results indicated that AgNPs with size of 2.6 and 18 nm decreased viability, proliferation and caused death of pancreatic cancer cells in a size- and concentration-dependent manner. Ultrastructural analysis identified that cellular uptake of AgNPs resulted in apoptosis, autophagy, necroptosis and mitotic catastrophe. These alterations were associated with increased pro-apoptotic protein Bax and decreased level of anti-apoptotic protein Bcl-2. Moreover, AgNPs significantly elevated the level of tumor suppressor p53 protein as well as necroptosis- and autophagy-related proteins: RIP-1, RIP-3, MLKL and LC3-II, respectively.

In addition, we found that PANC-1 cells were more vulnerable to AgNPs-induced cytotoxicity compared to pancreatic non-tumor cells.

In conclusion, AgNPs by inducing mixed type of programmed cell death in PANC-1 cells, could provide a new therapeutic strategy to overcome chemoresistance in one of the deadliest human cancer.

Recent developments in nanomedicine for melanoma treatment

Melanoma is a most aggressive skin cancer with limited therapeutic options and its incidence is increasing rapidly in recent years. The discovery and application of new targeted therapy agents have shown significant benefits. However, adverse side-effects and resistance to chemotherapy remain formidable challenges in the clinical treatment of malignant melanoma. Nanotherapeutics offers an important prospect of overcoming these drawbacks. The anti-tumoral applications of nanomedicine are varied, including those in chemotherapy, RNA interference, photothermal therapy, and photodynamic therapy. Furthermore, nanomedicine allows delivery of the effector structures into the tumor site via passive or active targeting, thereby allowing increased therapeutic specificity and reduced side effects. In this review, we summarize the latest developments in the application of nanocarrier-mediated targeted drug delivery to melanoma and nanomedicine-related clinical trials in melanoma treatment. We also discuss existing problems and opportunities for future developments, providing direction and new thoughts for further studies.

Nanotechnology for Food Packaging and Food Quality Assessment

Nanotechnology has paved the way to innovative food packaging materials and analytical methods to provide the consumers with healthier food and to reduce the ecological footprint of the whole food chain. Combining antimicrobial and antifouling properties, thermal and mechanical protection, oxygen and moisture barrier, as well as to verify the actual quality of food, e.g., sensors to detect spoilage, bacterial growth, and to monitor incorrect storage conditions, or anticounterfeiting devices in food packages may extend the products shelf life and ensure higher quality of foods. Also the ecological footprint of food chain can be reduced by developing new completely recyclable and/or biodegradable packages from natural and eco-friendly resources. The contribution of nanotechnologies to these goals is reviewed in this chapter, together with a description of portable devices ("lab-on-chip," sensors, nanobalances, etc.) which can be used to assess the quality of food and an overview of regulations in force on food contact materials.

Effect of platinum nanoparticles on cell death induced by ultrasound in human lymphoma U937 cells

In this study, we report on the potential use of platinum nanoparticles (Pt-NPs), a superoxide dismutase (SOD)/catalase mimetic antioxidant, in combination with 1MHz ultrasound (US) at an intensity of 0.4 W/cm(2), 10% duty factor, 100 Hz PRF, for 2 min. Apoptosis induction was assessed by DNA fragmentation assay, cell cycle analysis and Annexin V-FITC/PI staining. Cell killing was confirmed by cell counting and microscopic examination. The mitochondrial and Ca(2+)-dependent pathways were investigated. Caspase-8 expression and autophagy-related proteins were detected by spectrophotometry and western blot analysis, respectively. Intracellular reactive oxygen species (ROS) elevation was detected by flow cytometry, while extracellular free radical formation was assessed by electron paramagnetic resonance spin trapping spectrometry. The results showed that Pt-NPs exerted differential effects depending on their internalization. Pt-NPs functioned as potent free radical scavengers when added immediately before sonication while pre-treatment with Pt-NPs suppressed the induction of apoptosis as well as autophagy (AP), and resulted in enhanced cell killing. Dead cells displayed the features of pyknosis. The exact mode of cell death is still unclear. In conclusion, the results indicate that US-induced AP may contribute to cell survival post sonication. To our knowledge this is the first study to discuss autophagy as a pro-survival pathway in the context of US. The combination of Pt-NPs and US might be effective in cancer eradication.

A comparison of immunotoxic effects of nanomedicinal products with regulatory immunotoxicity testing requirements

Nanomaterials (NMs) are attractive for biomedical and pharmaceutical applications because of their unique physicochemical and biological properties. A major application area of NMs is drug delivery. Many nanomedicinal products (NMPs) currently on the market or in clinical trials are most often based on liposomal products or polymer conjugates. NMPs can be designed to target specific tissues, eg, tumors. In virtually all cases, NMPs will eventually reach the immune system. It has been shown that most NMs end up in organs of the mononuclear phagocytic system, notably liver and spleen. Adverse immune effects, including allergy, hypersensitivity, and immunosuppression, have been reported after NMP administration. Interactions of NMPs with the immune system may therefore constitute important side effects. Currently, no regulatory documents are specifically dedicated to evaluate the immunotoxicity of NMs or NMPs. Their immunotoxicity assessment is performed based on existing guidelines for conventional substances or medicinal products. Due to the unique properties of NMPs when compared with conventional medicinal products, it is uncertain whether the currently prescribed set of tests provides sufficient information for an adequate evaluation of potential immunotoxicity of NMPs. The aim of this study was therefore, to compare the current regulatory immunotoxicity testing requirements with the accumulating knowledge on immunotoxic effects of NMPs in order to identify potential gaps in the safety assessment. This comparison showed that immunotoxic effects, such as complement activation-related pseudoallergy, myelosuppression, inflammasome activation, and hypersensitivity, are not readily detected by using current testing guidelines. Immunotoxicity of NMPs would be more accurately evaluated by an expanded testing strategy that is equipped to stratify applicable testing for the various types of NMPs.

Determining the relationship between nanoparticle characteristics and immunotoxicity: key challenges and approaches

The growing wealth of information regarding the influence that physicochemical characteristics play on nanoparticle biocompatibility and safety is allowing improved design and rationale for their development and preclinical assessment. Accurate and appropriate measurement of these characteristics accompanied by informed toxicological assessment is a necessity for the development of safe and effective nanomedicines. While particle type, formulation and mode of administration dictate the individual causes for concern through development, the benefits of nanoformulation for treatment of the diseased state are great. Here we have proposed certain considerations and suggestions, which could lead to better-informed preclinical assessment of nanomaterials for nanomedicine, as well as how this information can and should be extrapolated to the physiological state of the end user.

Smart multifunctional nanoparticles in nanomedicine

Recent advances in nanotechnology caused a growing interest using nanomaterials in medicine to solve a number of issues associated with therapeutic agents. The fabricated nanomaterials with unique physical and chemical properties have been investigated for both diagnostic and therapeutic applications. Therapeutic agents have been combined with the nanoparticles to minimize systemic toxicity, increase their solubility, prolong the circulation half-life, reduce their immunogenicity and improve their distribution. Multifunctional nanoparticles have shown great promise in targeted imaging and therapy. In this review, we summarized the physical parameters of nanoparticles for construction of “smart” multifunctional nanoparticles and their various surface engineering strategies. Outlook and questions for the further researches were discussed.

Efficient delivery of chlorin e6 into ovarian cancer cells with octalysine conjugated superparamagnetic iron oxide nanoparticles for effective photodynamic therapy

Chlorin e6, loaded on the surface of SPION-PG-Lys₈ through electrostatic attraction, was delivered preferentially into mitochondria of SKOV3 ovarian cancer cells, improving efficacy of photodynamic therapy significantly.

Drug Delivery Systems for Imaging and Therapy of Parkinson's Disease

BACKGROUND

Although a variety of therapeutic approaches are available for the treatment of Parkinson's disease, challenges limit effective therapy. Among these challenges are delivery of drugs through the blood brain barier to the target brain tissue and the side effects observed during long term administration of antiparkinsonian drugs. The use of drug delivery systems such as liposomes, niosomes, micelles, nanoparticles, nanocapsules, gold nanoparticles, microspheres, microcapsules, nanobubbles, microbubbles and dendrimers is being investigated for diagnosis and therapy.

METHODS

This review focuses on formulation, development and advantages of nanosized drug delivery systems which can penetrate the central nervous system for the therapy and/or diagnosis of PD, and highlights future nanotechnological approaches.

RESULTS

It is esential to deliver a sufficient amount of either therapeutic or radiocontrast agents to the brain in order to provide the best possible efficacy or imaging without undesired degradation of the agent. Current treatments focus on motor symptoms, but these treatments generally do not deal with modifying the course of Parkinson's disease. Beyond pharmacological therapy, the identification of abnormal proteins such as α -synuclein, parkin or leucine-rich repeat serine/threonine protein kinase 2 could represent promising alternative targets for molecular imaging and therapy of Parkinson's disease.

CONCLUSION

Nanotechnology and nanosized drug delivery systems are being investigated intensely and could have potential effect for Parkinson's disease. The improvement of drug delivery systems could dramatically enhance the effectiveness of Parkinson's Disease therapy and reduce its side effects.

Negatively charged AuNP modified with monoclonal antibody against novel tumor antigen FAT1 for tumor targeting

BACKGROUND

Herein, we demonstrated the use of a newly generated anti FAT1 antibody (clone mAB198.3) for intracellular delivery of anionic gold NPs, to form active targeting Au nanoparticles with high payload characteristics.

METHODS

In vitro characterizations were determined by DLS, confocal microscopy, TEM, western blot, MALDI-TOF MS/MS analysis, MTT, ICP-MS and flow cytometry analysis. In vivo targeting efficacy was investigated by in vivo bio-imaging study and ICP-MS.

RESULTS

The specificity of the FAT1 recognition in colon cancer was confirmed by pre-adsorbing mAb198.3, adsorption dramatically abolished the antibody reactivity on colon cancer, thus confirming the binding specificity. The DLS size distribution profile of the AuCOOH, AuCOOH(Cy5)_ mAb198.3, AuCOOH(Cy5)_isotype has showed that the modified gold nanoparticles are well dispersed in water, PBS buffer and cell culture medium with 10 % FBS. By TEM measurement, the size of Au nanoparticles with spherical morphology is about 10-20 nm. AuCOOH_198.3 NPs were stable in an acidic environment, as well as in PBS buffer, cell culture media and media with 10 % serum. MTT results revealed that Au nanoparticles have well biocompatibility. TEM results indicated that conjugation of mAb198.3 on Au nanoparticles can be an effective delivery vehicle for negatively charged gold nanoparticles and increased its intracellular transport. It was also demonstrated by confocal microscopy that AuCOOH(Cy5)_mAb198.3 could attach to the cell membrane in very short time, then gradually delivered into cells. After 4 h incubation, almost all AuCOOH(Cy5)_mAb198.3 have been uptaken into or surrounding the cytoplasm and nucleus. In vivo results showed that only about 20 % of AuCOOH accumulated in tumor site due to EPR effect, while nearly 90 % of AuCOOH_mAb198.3 was found in tumor, providing sufficient evidence for receptor-specific targeting by mAb198.3.

CONCLUSION

According to in vitro and in vivo research results, the intracellular uptake of negatively charged AuCOOH_mAB198.3 particles is enhanced to a greater extent. Thus, AuCOOH_mAb198.3 holds significant potential to improve the treatment of cancer.

An insight on electrospun-nanofibers-inspired modern drug delivery system in the treatment of deadly cancers

This review gives an insight into the process of electrospinning, its essential parameters, the types of drug incorporation and the works reported on common dreadful cancers.

Autophagy as the effector and player in DNA damage response of cells to genotoxicants

In this review, we provide an overview and discuss the molecular mechanism of DNA damage induced autophagy, and their mutual regulation and its role in cell fate determination in response to genotoxic effects of environmental toxicants.

Cationic poly(amidoamine) dendrimers induced cyto-protective autophagy in hepatocellular carcinoma cells

Poly(amidoamine) (PAMAM) dendrimers are proposed as one of the most promising nanomaterials for biomedical applications because of their unique tree-like structure, monodispersity and tunable properties. In this study, we found that PAMAM dendrimers could induce the formation of autophagosomes and the conversion of microtubule-associated protein 1 light chain 3 (LC3) in hepatocellular carcinoma HepG2 cells, while the inhibition of the Akt/mTOR and activation of the Erk 1/2 signaling pathways were involved in autophagy-induced by PAMAM dendrimers. We also investigated the suppression of autophagy with the obviously enhanced cytotoxicity of PAMAM dendrimers. Moreover, the blockage of a reactive oxygen species (ROS) could enhance the growth inhibition and apoptosis of hepatocellular carcinoma cells, induced by PAMAM dendrimers through reducing autophagic effects. Taken together, these findings explored the role and mechanism of autophagy induced by PAMAM dendrimers in HepG2 cells, provided new insight into the effect of autophagy on drug delivery nanomaterials and tumor cells and contributed to the use of a drug delivery vehicle for hepatocellular carcinoma treatment.

Nanomaterial-induced autophagy: a new reversal MDR tool in cancer therapy?

Most of the therapeutic strategies to counteract cancer imply killing of malignant cells. The most exploited cell death mechanism in cancer therapies is apoptosis, but recently, a lot of papers report that other mechanisms, mainly autophagy, could represent a new line of attack in the fight against cancer. One of the limitations for the effectiveness of the approved clinical treatments is the phenomenon of multidrug resistance (MDR) which enables the cancer cells to develop resistance to therapy, especially for chemotherapy. The MDR mechanisms include (a) decreased uptake of drug, (b) reduced intracellular drug concentration by efflux pumps, (c) altered cell cycle checkpoints, (d) altered drug targets, (e) increased metabolism of drugs, (f) induced emergency response genes to impair apoptotic pathway, and (g) altered drug detoxification. Great efforts have been made to reverse MDR. Currently, autophagy and nanosized drug delivery systems (DDSs) belonging to nanomaterials (NMs) provide alternative strategies to circumvent MDR. Nanosized DDSs are very promising tools to accumulate chemotherapeutics at targeting sites and control temporal and spatial drug release into tumor cells. On the other hand, autophagy could overrule drug resistance upon its activation by ensuring cell death via switching its prosurvival role to a prodeath one or by mediating the occurrence of cell death, i.e., apoptosis or necrosis. Likewise, the autophagy inhibition could counteract MDR by sensitizing the cells to anticancer molecules, i.e., Src family tyrosine kinase (SFK) inhibitors or 5-fluorouracil. Noteworthy, autophagy has been recently indicated to be a common cellular response to NMs, corroborating the fascinating idea of the exploitation of NM-induced autophagy in nanomedicine therapy. This review focuses on recently published literature about the relationship between MDR reversal and NMs or autophagy pointing to hypothesize a pivotal role of autophagy modulation induced by NMs in counteracting MDR.