Photodynamic N-TiO2 Nanoparticle Treatment Induces Controlled ROS-mediated Autophagy and Terminal Differentiation of Leukemia Cells

A review on dendrimer-based nanoconjugates and their intracellular trafficking in cancer photodynamic therapy

Nanotechnology-based cancer treatment has received considerable attention, and these treatments generally use drug-loaded nanoparticles (NPs) to target and destroy cancer cells. Nanotechnology combined with photodynamic therapy (PDT) has demonstrated positive outcomes in cancer therapy. Combining nanotechnology and PDT is effective in targeting metastatic cancer cells. Nanotechnology can also increase the effectiveness of PDT by targeting cells at a molecular level. Dendrimer-based nanoconjugates (DBNs) are highly stable and biocompatible, making them suitable for drug delivery applications. Moreover, the hyperbranched structures in DBNs have the capacity to load hydrophobic compounds, such as photosensitizers (PSs) and chemotherapy drugs, and deliver them efficiently to tumour cells. This review primarily focuses on DBNs and their potential applications in cancer treatment. We discuss the chemical design, mechanism of action, and targeting efficiency of DBNs in tumour metastasis, intracellular trafficking in cancer treatment, and DBNs' biocompatibility, biodegradability and clearance properties. Overall, this study will provide the most recent insights into the application of DBNs and PDT in cancer therapy.

The impact of nanomaterials on autophagy across health and disease conditions

Autophagy, a catabolic process integral to cellular homeostasis, is constitutively active under physiological and stress conditions. The role of autophagy as a cellular defense response becomes particularly evident upon exposure to nanomaterials (NMs), especially environmental nanoparticles (NPs) and nanoplastics (nPs). This has positioned autophagy modulation at the forefront of nanotechnology-based therapeutic interventions. While NMs can exploit autophagy to enhance therapeutic outcomes, they can also trigger it as a pro-survival response against NP-induced toxicity. Conversely, a heightened autophagy response may also lead to regulated cell death (RCD), in particular autophagic cell death, upon NP exposure. Thus, the relationship between NMs and autophagy exhibits a dual nature with therapeutic and environmental interventions. Recognizing and decoding these intricate patterns are essential for pioneering next-generation autophagy-regulating NMs. This review delves into the present-day therapeutic potential of autophagy-modulating NMs, shedding light on their status in clinical trials, intervention of autophagy in the therapeutic applications of NMs, discusses the potency of autophagy for application as early indicator of NM toxicity.

Metal-based nanoparticles in cancer therapy: Exploring photodynamic therapy and its interplay with regulated cell death pathways

Photodynamic therapy (PDT) represents a non-invasive treatment strategy currently utilized in the clinical management of selected cancers and infections. This technique is predicated on the administration of a photosensitizer (PS) and subsequent irradiation with light of specific wavelengths, thereby generating reactive oxygen species (ROS) within targeted cells. The cellular effects of PDT are dependent on both the localization of the PS and the severity of ROS challenge, potentially leading to the stimulation of various cell death modalities. For many years, the concept of regulated cell death (RCD) triggered by photodynamic reactions predominantly encompassed apoptosis, necrosis, and autophagy. However, in recent decades, further explorations have unveiled additional cell death modalities, such as necroptosis, ferroptosis, cuproptosis, pyroptosis, parthanatos, and immunogenic cell death (ICD), which helps to achieve tumor cell elimination. Recently, nanoparticles (NPs) have demonstrated substantial advantages over traditional PSs and become important components of PDT, due to their improved physicochemical properties, such as enhanced solubility and superior specificity for targeted cells. This review aims to summarize recent advancements in the applications of different metal-based NPs as PSs or delivery systems for optimized PDT in cancer treatment. Furthermore, it mechanistically highlights the contribution of RCD pathways during PDT with metal NPs and how these forms of cell death can improve specific PDT regimens in cancer therapy.

Autophagy-mediated nanomaterials for tumor therapy

Autophagy is a lysosomal self-degradation pathway that plays an important protective role in maintaining intracellular environment. Deregulation of autophagy is related to several diseases, including cancer, infection, neurodegeneration, aging, and heart disease. In this review, we will summarize recent advances in autophagy-mediated nanomaterials for tumor therapy. Firstly, the autophagy signaling pathway for tumor therapy will be reviewed, including oxidative stress, mammalian target of rapamycin (mTOR) signaling and autophagy-associated genes pathway. Based on that, many autophagy-mediated nanomaterials have been developed and applied in tumor therapy. According to the different structure of nanomaterials, we will review and evaluate these autophagy-mediated nanomaterials' therapeutic efficacy and potential clinical application.

Syzygium cumini (L.) Extract-Derived Green Titanium Dioxide Nanoparticles Induce Caspase-Dependent Apoptosis in Hepatic Cancer Cells

An aqueous extract of Syzygium cumini seeds was utilized to green synthesize titanium dioxide nanoparticles (TiO2 NPs). UV-Visible, DLS, FTIR, XRD, FESEM, TEM, SAED, EDAX, and photoluminescence spectroscopy techniques were employed to characterize the prepared TiO2 nanoparticles. The rutile crystal structure of TiO2 NPs was revealed by XRD study. The TEM and FESEM images of the TiO2 NPs revealed an average particle size of 50-100 nm. We employed EDAX to investigate the elemental compositions of TiO2 NPs. The O-Ti-O stretching bands appeared in the FTIR spectrum of TiO2 NPs at wavenumbers of 495 cm-1. The absorption edge peaks of TiO2 NPs were found in the UV-vis spectra at 397 nm. The MTT study revealed that TiO2 NPs effectively inhibited the growth of liver cancer Hep3 and Hep-G2 cells. The results of the corresponding fluorescent staining assays showed that TiO2 NPs significantly increased ROS generation, decreased MMP, and induced apoptosis in both liver cancer Hep3 and Hep-G2 cells. TiO2 nanoparticles lessened SOD, CAT, and GSH levels while augmenting MDA contents in Hep3 and Hep-G2 cells. In both Hep3 and Hep-G2 cells treated with TiO2 NPs, the Bax, CytC, p53, caspase-3, -8, and -9 expressions were remarkably augmented, while Bcl-2 expression was reduced. Overall, these findings revealed that formulated TiO2 NPs treatment considerably inhibited growth and triggered apoptosis in Hep3 and HepG2 cells.

Autophagy and Biomaterials: A Brief Overview of the Impact of Autophagy in Biomaterial Applications

Macroautophagy (hereafter autophagy), a tightly regulated physiological process that obliterates dysfunctional and damaged organelles and proteins, has a crucial role when biomaterials are applied for various purposes, including diagnosis, treatment, tissue engineering, and targeted drug delivery. The unparalleled physiochemical properties of nanomaterials make them a key component of medical strategies in different areas, such as osteogenesis, angiogenesis, neurodegenerative disease treatment, and cancer therapy. The application of implants and their modulatory effects on autophagy have been known in recent years. However, more studies are necessary to clarify the interactions and all the involved mechanisms. The advantages and disadvantages of nanomaterial-mediated autophagy need serious attention in both the biological and bioengineering fields. In this mini-review, the role of autophagy after biomaterial exploitation and the possible related mechanisms are explored.

Antileukemic potential of Nile blue-mediated photodynamic therapy on HL60 human myeloid leukemia cells

Background/aim

Photodynamic therapy (PDT) has received great attention over the past decade in the treatment of diseases such as leukemia which is a cancer of the blood and bone marrow cells that causes a significant number of deaths worldwide. In this study, it was aimed to investigate the effects of Nile blue-mediated PDT (NB-mediated PDT) on HL60 cells.

Materials and methods

The effect of NB-mediated PDT on cell proliferation was evaluated with cell volume analysis using flow cytometry at 24 h. Cell apoptosis, ROS production, mitochondrial membrane potential, and cell cycle analysis were evaluated using annexin V-FITC, H2DCFDA, JC-1, and PI staining, respectively, by flow cytometry and fluorescence microscopy. The morphological and ultrastructural analyses were examined by Giemsa staining and SEM. CD11b staining is used to determine the differentiation of leukemia cells.

Results

NB-mediated PDT induced an apoptotic response at 12.5 μM in HL60 cells. When Giemsa staining and SEM images were evaluated, apoptotic bodies, holes, and occasional folds were detected on the surfaces of cells in the NB-mediated PDT group.

Conclusion

The NB-mediated PDT had no effect on the differentiation of leukemia cells, but this therapy affects the growth of HL60 cells in vitro, which may provide a new idea for removing leukemic cells from bone marrow intended for autologous transplant.

Immunomodulatory, Antioxidant, Anticancer, and Pharmacokinetic Activity of Ulvan, a Seaweed-Derived Sulfated Polysaccharide: An Updated Comprehensive Review

Cancer is one of the most worldwide spread diseases and causes maximum death. Treatment of cancer depends on the host immune system and the type of drugs. The inefficiency of conventional cancer treatments as a result of drug resistance, nontargeted delivery, and chemotherapy-related negative side effects has caused bioactive phytochemicals to come into focus. As a result, recent years have seen an increase in research into screening and identifying natural compounds with anticancer properties. Recent studies on the isolation and use of polysaccharides derived from various marine algal species have revealed a variety of biological activities, including antioxidant and anticancer properties. Ulvan is a polysaccharide derived from various green seaweeds of the Ulva species in the family Ulvaceae. It has been demonstrated to have potent anticancer and anti-inflammatory properties through the modulation of antioxidants. It is vital to understand the mechanisms underlying the biotherapeutic activities of Ulvan in cancer and its role in immunomodulation. In this context, we reviewed the anticancer effects of ulvan based on its apoptotic effects and immunomodulatory activity. Additionally, we also focused on its pharmacokinetic studies in this review. Ulvan is the most conceivable candidate for use as a cancer therapeutic agent and could be used to boost immunity. Moreover, it may be established as an anticancer drug once its mechanisms of action are understood. Due to its high food and nutritive values, it can be used as a possible dietary supplement for cancer patients in the near future. This review may provide fresh perspectives on the potential novel role of ulvan, reveal a brand-new cancer-prevention strategy, and improve human health.

Photodynamic Activity of TMPyP4/TiO2 Complex under Blue Light in Human Melanoma Cells: Potential for Cancer-Selective Therapy

The combination of TiO₂ nanoparticles (NPs) and photosensitizers (PS) may offer significant advantages in photodynamic therapy (PDT) of melanoma, such as improved cell penetration, enhanced ROS production, and cancer selectivity. In this study, we aimed to investigate the photodynamic effect of 5,10,15,20-(Tetra-N-methyl-4-pyridyl)porphyrin tetratosylate (TMPyP4) complexes with TiO₂ NPs on human cutaneous melanoma cells by irradiation with 1 mW/cm² blue light. The porphyrin conjugation with the NPs was analyzed by absorption and FTIR spectroscopy. The morphological characterization of the complexes was performed by Scanning Electron Microscopy and Dynamic Light Scattering. The singlet oxygen generation was analyzed by phosphorescence at 1270 nm. Our predictions indicated that the non-irradiated investigated porphyrin has a low degree of toxicity. The photodynamic activity of the TMPyP4/TiO₂ complex was assessed on the human melanoma Mel-Juso cell line and non-tumor skin CCD-1070Sk cell line treated with various concentrations of the PS and subjected to dark conditions and visible light-irradiation. The tested complexes of TiO₂ NPs with TMPyP4 presented cytotoxicity only after activation by blue light (405 nm) mediated by the intracellular production of ROS in a dose-dependent manner. The photodynamic effect observed in this evaluation was higher in melanoma cells than the effect observed in the non-tumor cell line, demonstrating a promising potential for cancer-selectivity in PDT of melanoma.

Self-delivery biomedicine for enhanced photodynamic therapy by feedback promotion of tumor autophagy

Reactive oxygen species (ROS) generated during photodynamic therapy (PDT) can induce autophagy to protect tumor cell from PDT-induced apoptosis. In this work, a self-delivery autophagy regulator (designated as CeCe) is developed for autophagy promotion sensitized PDT against tumor. Briefly, CeCe is prepared by the assembly of a photosensitizer of chlorin e6 (Ce6) and autophagy promoter of celastrol. By virtue of intermolecular interactions, Ce6 and celastrol are able to self-assemble into nanomedicine with great photodynamic performance and autophagy regulation capacity. Under light irradiation, CeCe would produce ROS in tumor cells to amplify the oxidative stress and promote cell autophagy. As a result, CeCe exhibits an enhanced photo toxicity by inducing autophagic cell death. In vivo experiments indicate that CeCe can predominantly accumulate in tumor tissue for a robust PDT. Moreover, CeCe has a superior therapeutic efficiency compared to monotherapy and combined treatment of Ce6 and celastrol, suggesting a synergistic antitumor effect of PDT and autophagy promotion. This self-delivery nanomedicine may advance the development of the co-delivery nanoplatform to improve the antitumor efficacy of PDT by promoting autophagy. STATEMENT OF SIGNIFICANCE: Autophagy is a "double-edged sword" in cellular homeostasis and metabolism, which can promote tumor progression but also induce an unknown impact on tumor inhibition. In this work, a self-delivery autophagy regulator (designated as CeCe) was developed for autophagy promotion sensitized photodynamic therapy (PDT). By virtue of intermolecular interactions, Ce6 and celastrol were found to self-assemble into stable CeCe without drug excipients, which exhibited great photodynamic performance and autophagy regulation capacity. In vitro and in vivo findings demonstrated a superior tumor suppression ability of CeCe over the monotherapy as well as the combined treatment of Ce6 and celastrol, suggesting a synergistic antitumor efficacy by PDT and autophagy promotion.

Temozolomide, Simvastatin and Acetylshikonin Combination Induces Mitochondrial-Dependent Apoptosis in GBM Cells, Which Is Regulated by Autophagy

Glioblastoma multiforme (GBM) is one of the deadliest cancers. Temozolomide (TMZ) is the most common chemotherapy used for GBM patients. Recently, combination chemotherapy strategies have had more effective antitumor effects and focus on slowing down the development of chemotherapy resistance. A combination of TMZ and cholesterol-lowering medications (statins) is currently under investigation in in vivo and clinical trials. In our current investigation, we have used a triple-combination therapy of TMZ, Simvastatin (Simva), and acetylshikonin, and investigated its apoptotic mechanism in GBM cell lines (U87 and U251). We used viability, apoptosis, reactive oxygen species, mitochondrial membrane potential (MMP), caspase-3/-7, acridine orange (AO) and immunoblotting autophagy assays. Our results showed that a TMZ/Simva/ASH combination therapy induced significantly more apoptosis compared to TMZ, Simva, ASH, and TMZ/Simva treatments in GBM cells. Apoptosis via TMZ/Simva/ASH treatment induced mitochondrial damage (increase of ROS, decrease of MMP) and caspase-3/7 activation in both GBM cell lines. Compared to all single treatments and the TMZ/Simva treatment, TMZ/Simva/ASH significantly increased positive acidic vacuole organelles. We further confirmed that the increase of AVOs during the TMZ/Simva/ASH treatment was due to the partial inhibition of autophagy flux (accumulation of LC3β-II and a decrease in p62 degradation) in GBM cells. Our investigation also showed that TMZ/Simva/ASH-induced cell death was depended on autophagy flux, as further inhibition of autophagy flux increased TMZ/Simva/ASH-induced cell death in GBM cells. Finally, our results showed that TMZ/Simva/ASH treatment potentially depends on an increase of Bax expression in GBM cells. Our current investigation might open new avenues for a more effective treatment of GBM, but further investigations are required for a better identification of the mechanisms.

Customizing delivery nano-vehicles for precise brain tumor therapy

Although some tumor has become a curable disease for many patients, involvement of the central nervous system (CNS) is still a major concern. The blood-brain barrier (BBB), a special structure in the CNS, protects the brain from bloodborne pathogens via its excellent barrier properties and hinders new drug development for brain tumor. Recent breakthroughs in nanotechnology have resulted in various nanovehicless (NPs) as drug carriers to cross the BBB by different strategys. Here, the complex compositions and special characteristics of causes of brain tumor formation and BBB are elucidated exhaustively. Additionally, versatile drug nanovehicles with their recent applications and their pathways on different drug delivery strategies to overcome the BBB obstacle for anti-brain tumor are briefly discussed. Customizing nanoparticles for brain tumor treatments is proposed to improve the efficacy of brain tumor treatments via drug delivery from the gut to the brain. This review provides a broad perspective on customizing delivery nano-vehicles characteristics facilitate drug distribution across the brain and pave the way for the creation of innovative nanotechnology-based nanomaterials for brain tumor treatments.

Nanoemulsion applications in photodynamic therapy

Nanoemulsion, or nanoscaled-size emulsions, is a thermodynamically stable system formed by blending two immiscible liquids, blended with an emulsifying agent to produce a single phase. Nanoemulsion science has advanced rapidly in recent years, and it has opened up new opportunities in a variety of fields, including pharmaceuticals, biotechnology, food, and cosmetics. Nanoemulsion has been recognized as a potential drug delivery technology for various drugs, such as photosensitizing agents (PS). In photodynamic therapy (PDT), PSs produce cytotoxic reactive oxygen species under specific light irradiation, which oxidize the surrounding tissues. Over the past decades, the idea of PS-loaded nanoemulsions has received researchers' attention due to their ability to overcome several limitations of common PSs, such as limited permeability, non-specific phototoxicity, hydrophobicity, low bioavailability, and self-aggregation tendency. This review aims to provide fundamental knowledge of nanoemulsion formulations and the principles of PDT. It also discusses nanoemulsion-based PDT strategies and examines nanoemulsion advantages for PDT, highlighting future possibilities for nanoemulsion use.

Effect of Coated Silver Nanoparticles on Cancerous vs. Healthy Cells

Unique properties of silver nanoparticles (NPs) ensure their wide applications, in biomedicine; for this reason, it is very important carefully to study the toxicity of such NPs. The influence of silver nanoparticles coated with natural resin (Ag NPs) on the morphological and functional features of healthy BHK-21 and cancerous Hep-2 cells were studied using fluorescence microscopy, MTT, and neutral red assays. Ag NPs induced morphological changes in both cell cultures. The modifications were dose-dependent and more pronounced with an increase in NPs concentration. The IC₅₀ value of Ag NPs for Hep-2 cells was found to be 2.19 ± 0.22 µg/mL, whereas for BHK-21 cells it was significantly (5x) higher at 10.92 ± 2.48 µg/mL. The use of NPs at a concentration close to IC₅₀ leads to significant increase (up to 40%) in the number of necrotic cells in cancerous cell population and a decrease in the number of mitotic cells (up to 1.3%). In noncancerous cells the cellular parameters were similar to the control cells. These data suggest that the silver nanoparticles coated with natural resin can be potentially used in cancer therapy.

Perturbation of autophagy: An intrinsic toxicity mechanism of nanoparticles

Nanoparticles (NPs) have been widely used for various purposes due to their unique physicochemical properties. Such widespread applications greatly increase the possibility of human exposure to NPs in various ways. Once entering the human body, NPs may interfere with cellular homeostasis and thus affect the physiological system. As a result, it is necessary to evaluate the potential disturbance of NPs to multiple cell functions, including autophagy. Autophagy is an important cell function to maintain cellular homeostasis, and minimizing the disturbance caused by NP exposures to autophagy is critical to nanosafety. Herein, we summarized the recent research progress in nanotoxicity with particular focuses on the perturbation of NPs to cell autophagy. The basic processes of autophagy and complex relationships between autophagy and major human diseases were further discussed to emphasize the importance of keeping autophagy under control. Moreover, the most recent advances on perturbation of different types of NPs to autophagy were also reviewed. Last but not least, we also discussed major research challenges and potential coping strategies and proposed a safe-by-design strategy towards safer applications of NPs.

Modified Titanium Dioxide as a Potential Visible-Light-Activated Photosensitizer for Bladder Cancer Treatment

Low oxygen concentration inside the tumor microenvironment represents a major barrier for photodynamic therapy of many malignant tumors, especially urothelial bladder cancer. In this context, titanium dioxide, which has a low cost and can generate high ROS levels regardless of local O₂ concentrations, could be a potential type of photosensitizer for treating this type of cancer. However, the use of UV can be a major disadvantage, since it promotes breakage of the chemical bonds of the DNA molecule on normal tissues. In the present study, we focused on the cytotoxic activities of a new material (Ti(OH)₄) capable of absorbing visible light and producing high amounts of ROS. We used the malignant bladder cell line MB49 to evaluate the effects of multiple concentrations of Ti(OH)₄ on the cytotoxicity, proliferation, migration, and production of ROS. In addition, the mechanisms of cell death were investigated using FACS, accumulation of lysosomal acid vacuoles, caspase-3 activity, and mitochondrial electrical potential assays. The results showed that exposure of Ti(OH)₄ to visible light stimulates the production of ROS and causes dose-dependent necrosis in tumor cells. Also, Ti(OH)₄ was capable of inhibiting the proliferation and migration of MB49 in low concentrations. An increase in the mitochondrial membrane potential associated with the accumulation of acid lysosomes and low caspase-3 activity suggests that type II cell death could be initiated by autophagic dysfunction mechanisms associated with high ROS production. In conclusion, the characteristics of Ti(OH)₄ make it a potential photosensitizer against bladder cancer.

Two-dimensional nanomaterials-added dynamism in 3D printing and bioprinting of biomedical platforms: Unique opportunities and challenges

The nanomaterials research spectrum has seen the continuous emergence of two-dimensional (2D) materials over the years. These highly anisotropic and ultrathin materials have found special attention in developing biomedical platforms for therapeutic applications, biosensing, drug delivery, and regenerative medicine. Three-dimensional (3D) printing and bioprinting technologies have emerged as promising tools in medical applications. The convergence of 2D nanomaterials with 3D printing has extended the application dynamics of available biomaterials to 3D printable inks and bioinks. Furthermore, the unique properties of 2D nanomaterials have imparted multifunctionalities to 3D printed constructs applicable to several biomedical applications. 2D nanomaterials such as graphene and its derivatives have long been the interest of researchers working in this area. Beyond graphene, a range of emerging 2D nanomaterials, such as layered silicates, black phosphorus, transition metal dichalcogenides, transition metal oxides, hexagonal boron nitride, and MXenes, are being explored for the multitude of biomedical applications. Better understandings on both the local and systemic toxicity of these materials have also emerged over the years. This review focuses on state-of-art 3D fabrication and biofabrication of biomedical platforms facilitated by 2D nanomaterials, with the comprehensive summary of studies focusing on the toxicity of these materials. We highlight the dynamism added by 2D nanomaterials in the printing process and the functionality of printed constructs.

Diverse biotechnological applications of multifunctional titanium dioxide nanoparticles: An up-to-date review

Titanium dioxide (TiO₂) nanoparticles (NPs) are one of the topmost widely used metallic oxide nanoparticles. Whether present in naked form or doped with metals or polymers, TiO₂ NPs perform immensely important functions. However, the alteration in size and shape by doping results in improving the physical, chemical, and biological behaviour of TiO₂ NPs. Hence, the differential effects of various TiO₂ nanostructures including nanoflakes, nanoflowers, and nanotubes in various domains of biotechnology have been elucidated by researchers. Recently, the exponential growth of research activities regarding TiO₂ NPs has been observed owing to their chemical stability, low toxicity, and multifaceted properties. Because of their enormous abundance, plants, humans, and environment are inevitably exposed to TiO₂ NPs. These NPs play a significant role in improving agricultural attributes, removing environmental pollution, and upgrading the domain of nanomedicine. Therefore, the currently ongoing studies about the employment of TiO₂ NPs in enhancement of different aspects of agriculture, environment, and medicine have been extensively discussed in this review.

MAP kinase-dependent autophagy controls phorbol myristate acetate-induced macrophage differentiation of HL-60 leukemia cells

We investigated the mechanisms and the role of autophagy in the differentiation of HL-60 human acute myeloid leukemia cells induced by protein kinase C (PKC) activator phorbol myristate acetate (PMA). PMA-triggered differentiation of HL-60 cells into macrophage-like cells was confirmed by cell-cycle arrest accompanied by elevated expression of macrophage markers CD11b, CD13, CD14, CD45, EGR1, CSF1R, and IL-8. The induction of autophagy was demonstrated by the increase in intracellular acidification, accumulation/punctuation of autophagosome marker LC3-II, and the increase in autophagic flux. PMA also increased nuclear translocation of autophagy transcription factors TFEB, FOXO1, and FOXO3, as well as the expression of several autophagy-related (ATG) genes in HL-60 cells. PMA failed to activate autophagy inducer AMP-activated protein kinase (AMPK) and inhibit autophagy suppressor mechanistic target of rapamycin complex 1 (mTORC1). On the other hand, it readily stimulated the phosphorylation of mitogen-activated protein (MAP) kinases extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) via a protein kinase C-dependent mechanism. Pharmacological or genetic inhibition of ERK or JNK suppressed PMA-triggered nuclear translocation of TFEB and FOXO1/3, ATG expression, dissociation of pro-autophagic beclin-1 from its inhibitor BCL2, autophagy induction, and differentiation of HL-60 cells into macrophage-like cells. Pharmacological or genetic inhibition of autophagy also blocked PMA-induced macrophage differentiation of HL-60 cells. Therefore, MAP kinases ERK and JNK control PMA-induced macrophage differentiation of HL-60 leukemia cells through AMPK/mTORC1-independent, TFEB/FOXO-mediated transcriptional and beclin-1-dependent post-translational activation of autophagy.

N-Doped Graphene Quantum Dots/Titanium Dioxide Nanocomposites: A Study of ROS-Forming Mechanisms, Cytotoxicity and Photodynamic Therapy

Titanium dioxide nanoparticles (TiO2 NPs) have been proven to be potential candidates in cancer therapy, particularly photodynamic therapy (PDT). However, the application of TiO2 NPs is limited due to the fast recombination rate of the electron (e−)/hole (h+) pairs attributed to their broader bandgap energy. Thus, surface modification has been explored to shift the absorption edge to a longer wavelength with lower e−/h+ recombination rates, thereby allowing penetration into deep-seated tumors. In this study, TiO2 NPs and N-doped graphene quantum dots (QDs)/titanium dioxide nanocomposites (N-GQDs/TiO2 NCs) were synthesized via microwave-assisted synthesis and the two-pot hydrothermal method, respectively. The synthesized anatase TiO2 NPs were self-doped TiO2 (Ti3+ ions), have a small crystallite size (12.2 nm) and low bandgap energy (2.93 eV). As for the N-GQDs/TiO2 NCs, the shift to a bandgap energy of 1.53 eV was prominent as the titanium (IV) tetraisopropoxide (TTIP) loading increased, while maintaining the anatase tetragonal crystal structure with a crystallite size of 11.2 nm. Besides, the cytotoxicity assay showed that the safe concentrations of the nanomaterials were from 0.01 to 0.5 mg mL−1. Upon the photo-activation of N-GQDs/TiO2 NCs with near-infrared (NIR) light, the nanocomposites generated reactive oxygen species (ROS), mainly singlet oxygen (1O2), which caused more significant cell death in MDA-MB-231 (an epithelial, human breast cancer cells) than in HS27 (human foreskin fibroblast). An increase in the N-GQDs/TiO2 NCs concentrations elevates ROS levels, which triggered mitochondria-associated apoptotic cell death in MDA-MB-231 cells. As such, titanium dioxide-based nanocomposite upon photoactivation has a good potential as a photosensitizer in PDT for breast cancer treatment.

Photodynamic cancer therapy using liposomes as an advanced vesicular photosensitizer delivery system

The multidisciplinary field of photodynamic therapy (PDT) is a combination of photochemistry and photophysics sciences, which has shown tremendous potential for cancer therapy application. PDT employs a photosensitizing agent (PS) and light to form cytotoxic reactive oxygen species and subsequently oxidize light-exposed tissue. Despite numerous advantages of PDT and enormous progress in this field, common PSs are still far from ideal treatment because of their poor permeability, non-specific phototoxicity, side effects, hydrophobicity, weak bioavailability, and tendency to self-aggregation. To circumvent these limitations, PS can be encapsulated in liposomes, an advanced drug delivery system that has demonstrated the ability to enhance drug permeability into biological membranes and loading both hydrophobic and lipophilic agents. Moreover, liposomes can also be coated by targeting agents to improve delivery efficiency. The present review aims to summarize the principles of PDT, various PS generations, PS-loaded nanoparticles, liposomes, and their impact on PDT, then discuss recent photodynamic cancer therapy strategies using liposomes as PS-loaded vectors, and highlight future possibilities and perspectives.

Dietary polyphenols in chemoprevention and synergistic effect in cancer: Clinical evidences and molecular mechanisms of action

BACKGROUND

Epidemiological studies has revealed that a diet rich in fruits and vegetables could lower the risk of certain cancers. In this setting, natural polyphenols are potent anticancer bioactive compounds to overcome the non-target specificity, undesirable cytotoxicity and high cost of treatment cancer chemotherapy.

PURPOSE

The review focuses on diverse classifications of the chemical diversity of dietary polyphenol and their molecular targets, modes of action, as well as preclinical and clinical applications in cancer prevention.

RESULTS

The dietary polyphenols exhibit chemo-preventive activity through modulation of apoptosis, autophagy, cell cycle progression, inflammation, invasion and metastasis. Polyphenols possess strong antioxidant activity and control multiple molecular events through activation of tumor suppressor genes and inhibition of oncogenes involved in carcinogenesis. Numerous in vitro and in vivo studies have evidenced that these dietary phytochemicals regulate critical molecular targets and pathways to limit cancer initiation and progression. Moreover, natural polyphenols act synergistically with existing clinically approved drugs. The improved anticancer activity of combinations of polyphenols and anticancer drugs represents a promising perspective for clinical applications against many human cancers.

CONCLUSION

The anticancer properties exhibited by dietary polyphenols are mainly attributed to their anti-metastatic, anti-proliferative, anti-angiogenic, anti-inflammatory, cell cycle arrest, apoptotic and autophagic effects. Hence, regular consumption of dietary polyphenols as food or food additives or adjuvants can be a promising tactic to preclude adjournment or cancer therapy.

Inhibition of Autophagy Flux Promotes Secretion of Chondroitin Sulfate Proteoglycans in Primary Rat Astrocytes

Following spinal cord injury (SCI), reactive astrocytes in the glial scar produce high levels of chondroitin sulfate proteoglycans (CSPGs), which are known to inhibit axonal regeneration. Transforming growth factor beta (TGFβ) is a well-known factor that induces the production of CSPGs, and in this study, we report a novel mechanism underlying TGFβ's effects on CSPG secretion in primary rat astrocytes. We observed increased TGFβ-induced secretion of the CSPGs neurocan and brevican, and this occurred simultaneously with inhibition of autophagy flux. In addition, we show that neurocan and brevican levels are further increased when TGFβ is administered in the presence of an autophagy inhibitor, Bafilomycin-A1, while they are reduced when cells are treated with a concentration of rapamycin that is not sufficient to induce autophagy. These findings suggest that TGFβ mediates its effects on CSPG secretion through autophagy pathways. They also represent a potential new approach to reduce CSPG secretion in vivo by targeting autophagy pathways, which could improve axonal regeneration after SCI.

Chemical diversity of dietary phytochemicals and their mode of chemoprevention

Despite the advancement in prognosis, diagnosis and treatment, cancer has emerged as the second leading cause of disease-associated death across the globe. With the remarkable application of synthetic drugs in cancer therapy and the onset of therapy-associated adverse effects, dietary phytochemicals have been materialized as potent anti-cancer drugs owing to their antioxidant, apoptosis and autophagy modulating activities. With dynamic regulation of apoptosis and autophagy in association with cell cycle regulation, inhibition in cellular proliferation, invasion and migration, dietary phytochemicals have emerged as potent anti-cancer pharmacophores. Dietary phytochemicals or their synthetic analogous as individual drug candidates or in combination with FDA approved chemotherapeutic drugs have exhibited potent anti-cancer efficacy. With the advancement in cancer therapeutics, dietary phytochemicals hold high prevalence for their use as precision and personalized medicine to replace conventional chemotherapeutic drugs. Hence, keeping these perspectives in mind, this review focuses on the diversity of dietary phytochemicals and their molecular mechanism of action in several cancer subtypes and tumor entities. Understanding the possible molecular key players involved, the use of dietary phytochemicals will thrive a new horizon in cancer therapy.

Chemosensitivity enhanced by autophagy inhibition based on a polycationic nano-drug carrier

In recent years, with the increasing understanding of the role of autophagy in tumorigenesis and development, a steady stream of studies have demonstrated that both excessive induction and inhibition of autophagy could effectively improve the therapeutic efficacy against tumors during cytotoxic or molecularly targeted drug therapy. Among them, autophagy inhibition mediated by nanomaterials has become an appealing notion in nanomedicine therapeutics, since it can be exploited as an effective adjuvant in chemotherapy or as a potential anti-tumor agent. Herein, we constructed a pH-sensitive nanoplatform loaded with epirubicin (EPI) (mPEG-b-P(DPA-b-DMAEMA)/EPI), enabling effective autophagy inhibition in the process of tumor-targeting therapy and further sensitized the tumors to EPI. It was found that polycationic nanomicelles (PEDD-Ms) displayed specific localization in lysosomes after entering tumor cells and caused the impairment of lysosomal degradation capacity through lysosomal alkalization in a dose-dependent manner. HepG2 cells treated with PEDD-Ms displayed a large-scale accumulation of autophagosomes and LC3 (an autophagosome marker protein), and the degradation of the autophagy substrate p62 was also blocked, which indicated that these functional nanomicelles could significantly inhibit autophagy. Meanwhile, the typical morphological characteristics of autophagosomes were directly visualized by TEM. In vivo results also showed that the tumor-targeted and autophagy inhibition-associated nanoplatform therapy could effectively improve the therapeutic efficiency of EPI, which may be partially attributed to the fact that autophagy inhibition could enhance the sensitivity of tumor cells to EPI. Overall, we revealed the effect of polycationic nanomicelles on autophagic processes in tumor cells and explored their possible molecular mechanism, also considering the synergistic outcome between autophagy mediated by nanomaterials and chemotherapeutic drugs to improve the therapeutic effect on tumors.

Intracellular and extracellular targets as mechanisms of cancer therapy by nanomaterials in relation to their physicochemical properties

Cancer nanomedicine has evolved in recent years and is only expected to increase due to the ease with which nanomaterials (NMs) may be manipulated to the advantage of the cancer patient. The success of nanomedicine is dependent on the cell death mechanism, which in turn is dependent on the organelle initially targeted. The success of cancer nanomedicine is also dependent on other cellular mechanisms such as the induction of autophagy dysfunction, manipulation of the tumor microenvironment (TME) and secretome or induction of host immune responses. Current cancer phototherapies for example, photothermal- or photodynamic therapies as well as radio enhancement also form a major part of cancer nanomedicine. In general, cancer nanomedicine may be grouped into those NMs exhibiting inherent anti-cancer properties that is, self-therapeutic NMs (Group 1), NMs leading to localization of phototherapies or radio-enhancement (Group 2), and NMs as nanocarriers in the absence or presence of external radiation (Group 3). The recent advances of these three groups, together with their advantages and disadvantages as well as their cellular mechanisms and ultimate outcomes are summarized in this review. By exploiting these different intracellular mechanisms involved in initiating cell death pathways, it is possible to synthesize NMs that may have the desirable characteristics to maximize their efficacy in cancer therapy. Therefore, a summary of these important physicochemical characteristics is also presented that need to be considered for optimal cancer cell targeting and initiation of mechanisms that will lead to cancerous cell death. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Mathematical modeling and experimental analysis of the efficacy of photodynamic therapy in conjunction with photo thermal therapy and PEG-coated Au-doped TiO2 nanostructures to target MCF-7 cancerous cells

Some nanoscale morphologies of titanium oxide nanostructures blend with gold nanoparticles and act as satellites and targeted weapon methodologies in biomedical applications. Simultaneously, titanium oxide can play an important role when combined with gold after blending with polyethylene glycol (PEG). Our experimental approach is novel with respect to the plasmonic role of metal nanoparticles as an efficient PDT drug. The current experimental strategy floats the comprehensive and facile way of experimental strategy on the critical influence that titanium with gold nanoparticles used as novel photosensitizing agents after significant biodistribution of proposed nanostructures toward targeted site. In addition, different morphologies of PEG-coated Au-doped titanium nanostructures were shown to provide various therapeutic effects due to a wide range of electromagnetic field development. This confirms a significantly amplified population of hot electron generation adjacent to the interface between Au and TiO₂ nanostructures, leading to maximum cancerous cell injury in the MCF-7 cell line. The experimental results were confirmed by applying a least squares fit math model which verified our results with 99% goodness of fit. These results can pave the way for comprehensive rational designs for satisfactory response of performance phototherapeutic model mechanisms along with new horizons of photothermal therapy (HET) and photodynamic therapy (HET) operating under visible and near-infrared (NIR) light.

Role of PFKFB3 and PFKFB4 in Cancer: Genetic Basis, Impact on Disease Development/Progression, and Potential as Therapeutic Targets

Glycolysis is a crucial metabolic process in rapidly proliferating cells such as cancer cells. Phosphofructokinase-1 (PFK-1) is a key rate-limiting enzyme of glycolysis. Its efficiency is allosterically regulated by numerous substances occurring in the cytoplasm. However, the most potent regulator of PFK-1 is fructose-2,6-bisphosphate (F-2,6-BP), the level of which is strongly associated with 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase activity (PFK-2/FBPase-2, PFKFB). PFK-2/FBPase-2 is a bifunctional enzyme responsible for F-2,6-BP synthesis and degradation. Four isozymes of PFKFB (PFKFB1, PFKFB2, PFKFB3, and PFKFB4) have been identified. Alterations in the levels of all PFK-2/FBPase-2 isozymes have been reported in different diseases. However, most recent studies have focused on an increased expression of PFKFB3 and PFKFB4 in cancer tissues and their role in carcinogenesis. In this review, we summarize our current knowledge on all PFKFB genes and protein structures, and emphasize important differences between the isoenzymes, which likely affect their kinase/phosphatase activities. The main focus is on the latest reports in this field of cancer research, and in particular the impact of PFKFB3 and PFKFB4 on tumor progression, metastasis, angiogenesis, and autophagy. We also present the most recent achievements in the development of new drugs targeting these isozymes. Finally, we discuss potential combination therapies using PFKFB3 inhibitors, which may represent important future cancer treatment options.

Recent Trends in Photoacoustic Imaging Techniques for 2D Nanomaterial-Based Phototherapy

A variety of 2D materials have been developed for therapeutic biomedical studies. Because of their excellent physicochemical properties, 2D materials can be used as carriers for delivering therapeutic agents into a lesion, leading to phototherapy. Various optical imaging techniques have been used for the monitoring of the treatment process. Among these, photoacoustic imaging has unique advantages including relatively deep imaging depth and large field of view with high spatial resolution. In this review article, we summarize the types of photoacoustic imaging systems used for phototherapy monitoring, then we explore contrast-enhanced photoacoustic images using 2D materials. Finally, photoacoustic image-guided phototherapies are discussed. We conclude that 2D material-based phototherapy can be efficiently monitored by photoacoustic imaging techniques.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Chemotherapeutic efficacy of curcumin and resveratrol against cancer: Chemoprevention, chemoprotection, drug synergism and clinical pharmacokinetics

The frequent inefficiency of conventional cancer therapies due to drug resistance, non-targeted drug delivery, chemotherapy-associated toxic side effects turned the focus to bioactive phytochemicals. In this context, curcumin and resveratrol have emerged as potent chemopreventive and chemoprotective compounds modulating apoptotic and autophagic cell death pathways in cancer in vitro and in vivo. As synergistic agents in combination with clinically established anticancer drugs, the enhanced anticancer activity at reduced chemotherapy-associated toxicity towards normal organs can be explained by improved pharmacokinetics, pharmacodynamics, bioavailability and metabolism. With promising preclinical and clinical applications, the design of drug-loaded nanoparticles, nanocarriers, liposomes and micelles have gained much attention to improve target specificity and drug efficacy. The present review focuses on the molecular modes of chemoprevention, chemoprotection and drug synergism with special emphasis to preclinical and clinical applications, pharmacokinetics, pharmacodynamics and advanced drug delivery methods for the development of next-generation personalized cancer therapeutics.

Autophagy and Leukemia

Leukemia is a malignant clonal disease that originates from hematopoietic stem cells. As in-depth research examines the molecular biology and immunology of the hematopoietic system, leukemia treatment has evolved from a single cytotoxic drug to treatments that inducing differentiation and apoptosis. Meanwhile, autophagy has become a growing concern as a new form of cell death. The immune response, hematopoietic stem cell differentiation, and drug resistance of tumor cells are all potentially affected by autophagy. Regulating autophagy may become one of the promising directions in the field of targeted therapy.

Platinum nanoparticles induced genotoxicity and apoptotic activity in human normal and cancer hepatic cells via oxidative stress-mediated Bax/Bcl-2 and caspase-3 expression

Platinum nanoparticles (PtNPs) attract much attention due to their excellent biocompatibility and catalytic properties, but their toxic effects on normal (CHANG) and cancerous (HuH-7) human liver cells are meagre. The cytotoxic and apoptotic effects of PtNPs (average size, 3 nm) were determined in CHANG and HuH-7 cells. After treating these cells were with PtNPs (10, 50, 100, 200, and 300 μg/mL) for 24 and 48 hours, we observed dose- and time-dependent cytotoxicity, as evaluated by using (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide, a tetrazole) (MTT) and neutral red uptake (NRU) assays. The production of reactive oxygen species (ROS) was increased in both cells after treatment with the above dose of PtNPs for 24 and 48 hours. Determination of morphological changes of cells, chromosome condensation, mitochondrial membrane potential, and caspase-3 assays showed that PtNPs induce cytotoxicity and apoptosis in CHANG and HuH-7 cells by altering the cell morphology and density, increasing cell population in apoptosis, and causing chromosome condensation. Furthermore, we have studied fragmentation of DNA using alkaline single cell gel electrophoresis and expression of apoptotic genes by real-time PCR (RT-PCR). The percentage of DNA fragmentation was more at 300 μg/mL for 48 hours in both cells, but slightly more fragmentation was found in HuH-7 relative to CHANG cells. Considering all of the above parameters, PtNPs elicited cytotoxicity on CHANG and HuH-7 cells by blocking cell proliferation and inducing apoptosis. Thus this study may be useful in in vitro laboratory studies using cell lines for screening the genotoxic and apoptotic potential of nanoparticles.

Targeting non-apoptotic cell death in cancer treatment by nanomaterials: Recent advances and future outlook

Many tumors develop resistance to most of the apoptosis-based cancer therapies. In this sense targeting non-apoptotic forms of cell death including necroptosis, autophagy and ferroptosis may have therapeutic benefits in apoptosis-defective cancer cells. Nanomaterials have shown great advantages in cancer treatment owing to their unique characteristics. Besides, the capability of nanomaterials to induce different forms of cell death has gained widespread attention in cancer treatment. Reports in this field reflect the therapeutic potential of necroptotic cell death induced by nanomaterials in cancer. Also, autophagic cell death induced by nanomaterials alone and as a part of chemo-, radio- and photothermal therapy holds great promise as anticancer therapeutic option. Besides, ferroptosis induction by iron-based nanomaterials in drug delivery, immunotherapy, hyperthermia and imaging systems shows promising results in malignancies. Hence, this review is devoted to the latest efforts and the challenges in this field of research and its clinical merits.

Reprogramming and transdifferentiation - two key processes for regenerative medicine

Regenerative medicine based on transplants obtained from donors or foetal and new-born mesenchymal stem cells, encounter important obstacles such as limited availability of organs, ethical issues and immune rejection. The growing demand for therapeutic methods for patients being treated after serious accidents, severe organ dysfunction and an increasing number of cancer surgeries, exceeds the possibilities of the therapies that are currently available. Reprogramming and transdifferentiation provide powerful bioengineering tools. Both procedures are based on the somatic differentiated cells, which are easily and unlimitedly available, like for example: fibroblasts. During the reprogramming procedure mature cells are converted into pluripotent cells - which are capable to differentiate into almost any kind of desired cells. Transdifferentiation directly converts differentiated cells of one type into another differentiated cells type. Both procedures allow to obtained patient's dedicated cells for therapeutic purpose in regenerative medicine. In combination with biomaterials, it is possible to obtain even whole anatomical structures. Those patient's dedicated structures may serve for them upon serious accidents with massive tissue damage but also upon cancer surgeries as a replacement of damaged organ. Detailed information about reprogramming and transdifferentiation procedures as well as the current state of the art are presented in our review.

TiO2 nanoparticles enhance the chemotherapeutic effects of 5-fluorouracil in human AGS gastric cancer cells via autophagy blockade

AIMS

Nanoparticles (NPs)-based drugs have been recently introduced to improve the efficacy of current therapeutic strategies for the treatment of cancer; however, the molecular mechanisms by which a NP interacts with cellular systems still need to be delineated. Here, we utilize the autophagic potential of TiO2 NPs for improving chemotherapeutic effects of 5-fluorouracil (5-FU) in human AGS gastric cells.

MATERIALS AND METHODS

Cell growth and viability were determined by trypan blue exclusion test and MTT assay, respectively. Vesicular organelles formation was evaluated by acridine orange staining of cells. Cell cycle and apoptosis were monitored by flow cytometry. Reactive oxygen species (ROS) level were measured by DCHF-DA staining. Autophagy was examined by q-PCR and western blotting. Molecular docking was used for studying NP interaction with autophagic proteins.

KEY FINDINGS

TiO2 NPs increase ROS production, impair lysosomal function and subsequently block autophagy flux in AGS cells. In addition, the autophagy blockade induced by non-toxic concentrations of TiO2 NPs (1 μg/ml) can promote cytotoxic and apoptotic effects of 5-FU in AGS cells.

SIGNIFICANCE

These results confirm the beneficial effects of TiO2 NPs in combination with chemotherapy in in vitro model of gastric cancer, which may pave the way to develop a possible solution to circumvent chemoresistance in cancer.

Biological Factors, Metals, and Biomaterials Regulating Osteogenesis through Autophagy

Bone loss raises great concern in numerous situations, such as ageing and many diseases and in both orthopedic and dentistry fields of application, with an extensive impact on health care. Therefore, it is crucial to understand the mechanisms and the determinants that can regulate osteogenesis and ensure bone balance. Autophagy is a well conserved lysosomal degradation pathway, which is known to be highly active during differentiation and development. This review provides a revision of the literature on all the exogen factors that can modulate osteogenesis through autophagy regulation. Metal ion exposition, mechanical stimuli, and biological factors, including hormones, nutrients, and metabolic conditions, were taken into consideration for their ability to tune osteogenic differentiation through autophagy. In addition, an exhaustive overview of biomaterials, both for orthopedic and dentistry applications, enhancing osteogenesis by modulation of the autophagic process is provided as well. Already investigated conditions regulating bone regeneration via autophagy need to be better understood for finely tailoring innovative therapeutic treatments and designing novel biomaterials.

The Current Understanding of Autophagy in Nanomaterial Toxicity and Its Implementation in Safety Assessment-Related Alternative Testing Strategies

Nanotechnology has rapidly promoted the development of a new generation of industrial and commercial products; however, it has also raised some concerns about human health and safety. To evaluate the toxicity of the great diversity of nanomaterials (NMs) in the traditional manner, a tremendous number of safety assessments and a very large number of animals would be required. For this reason, it is necessary to consider the use of alternative testing strategies or methods that reduce, refine, or replace (3Rs) the use of animals for assessing the toxicity of NMs. Autophagy is considered an early indicator of NM interactions with cells and has been recently recognized as an important form of cell death in nanoparticle-induced toxicity. Impairment of autophagy is related to the accelerated pathogenesis of diseases. By using mechanism-based high-throughput screening in vitro, we can predict the NMs that may lead to the generation of disease outcomes in vivo. Thus, a tiered testing strategy is suggested that includes a set of standardized assays in relevant human cell lines followed by critical validation studies carried out in animals or whole organism models such as C. elegans (Caenorhabditis elegans), zebrafish (Danio rerio), and Drosophila (Drosophila melanogaster)for improved screening of NM safety. A thorough understanding of the mechanisms by which NMs perturb biological systems, including autophagy induction, is critical for a more comprehensive elucidation of nanotoxicity. A more profound understanding of toxicity mechanisms will also facilitate the development of prevention and intervention policies against adverse outcomes induced by NMs. The development of a tiered testing strategy for NM hazard assessment not only promotes a more widespread adoption of non-rodent or 3R principles but also makes nanotoxicology testing more ethical, relevant, and cost- and time-efficient.

Differential effects of N-TiO2 nanoparticle and its photo-activated form on autophagy and necroptosis in human melanoma A375 cells

The manipulation of autophagy provides a new opportunity for highly effective anticancer therapies. Recently, we showed that photodynamic therapy (PDT) with nitrogen-doped titanium dioxide (N-TiO₂ ) nanoparticles (NPs) could promote the reactive oxygen species (ROS)-dependent autophagy in leukemia cells. However, the differential autophagic effects of N-TiO₂ NPs in the dark and light conditions and the potential of N-TiO_2- based PDT for the treatment of melanoma cells remain unknown. Here we show that depending on the visible-light condition, the autophagic response of human melanoma A375 cells to N-TiO₂ NPs switches between two different statuses (ie., flux or blockade) with the opposite outcomes (ie., survival or death). Mechanistically, low doses of N-TiO₂ NPs (1-100 µg/ml) stimulate a nontoxic autophagy flux response in A375 cells, whereas their photo-activation leads to the impairment of the autophagosome-lysosome fusion, the blockade of autophagy flux and consequently the induction of RIPK1-mediated necroptosis via ROS production. These results confirm that photo-controllable autophagic effects of N-TiO₂ NPs can be utilized for the treatment of cancer, particularly melanoma.

Delayed effects of sulfur mustard on autophagy suppression in chemically-injured lung tissue

BACKGROUND

Autophagy is an intracellular hemostasis mechanism, responding to extracellular or intracellular stresses. Sulfur mustard (SM) induces cellular stress. Iranian soldiers exposed to SM gas, during the Iraq-Iran war, suffer from delayed complications even 30 years after exposure. In this study, for exploring the SM effect on autophagy pathway, gene and protein expression of autophagy markers are evaluated in the lung of SM-exposed people.

METHODS

52 FFPE lung tissues of SM-exposed people and 33 lung paraffin blocks of non-exposed patients to SM were selected. LC3 and Beclin-1 mRNA expressions were evaluated by QRT-PCR. LC3-B protein and LC3II/LC3I proteins ratio were detected by Immunohistochemistry and immunoblotting method. The collected data were analyzed in SPSS, and P value ≤ 0.05 was considered significant.

RESULTS

LC3 gene expression in SM-exposed subjects (median CT value = 4.97) increased about 4 fold compared with the control group (median CT value = 0.46, P = 0.025). Beclin-1 mRNA expression had not significant difference between two groups. After adjusting the confounding variables such as drug usage, LC3-B protein (P = 0.041) and LC3II/LC3I ratio (P = 0.044) were found significantly lower in the lung cells of SM-exposed group.

CONCLUSION

Upon exposure to SM gas, the lung cells are affected by acute cellular stress such as oxidative stress. The study results show that LC3 mRNA level increases in these patients, but, surprisingly, LC3-B protein via unknown mechanism has been down-regulated. N-acetyl cysteine and salbutamol drugs could induce the autophagy, and help to reduce the SM effects and improve the clinical condition of SM-injured patients.

Near Infrared-Activated Dye-Linked ZnO Nanoparticles Release Reactive Oxygen Species for Potential Use in Photodynamic Therapy

Novel dye-linked zinc oxide nanoparticles (NPs) hold potential as photosensitizers for biomedical applications due to their excellent thermal- and photo-stability. The particles produced reactive oxygen species (ROS) upon irradiation with 850 nm near infrared (NIR) light in a concentration- and time-dependent manner. Upon irradiation, ROS detected in vitro in human umbilical vein endothelial cells (HUVEC) and human carcinoma MCF7 cells positively correlated with particle concentration and interestingly, ROS detected in MCF7 was higher than in HUVEC. Preferential cytotoxicity was also exhibited by the NPs as cell killing was higher in MCF7 than in HUVEC. In the absence of irradiation, dye-linked ZnO particles minimally affected the viability of cell (HUVEC) at low concentrations (<30 μg/mL), but viability significantly decreased at higher particle concentrations, suggesting a need for particle surface modification with poly (ethylene glycol) (PEG) for improved biocompatibility. The presence of PEG on particles after dialysis was indicated by an increase in size, an increase in zeta potential towards neutral, and spectroscopy results. Cell viability was improved in the absence of irradiation when cells were exposed to PEG-coated, dye-linked ZnO particles compared to non-surface modified particles. The present study shows that there is potential for biological application of dye-linked ZnO particles in photodynamic therapy.

Mechanoregulation of titanium dioxide nanoparticles in cancer therapy

Titanium dioxide (TiO₂) nanoparticles (NPs), first developed in the 1990s, have been applied in numerous biomedical fields such as tissue engineering and therapeutic drug development. In recent years, TiO₂-based drug delivery systems have demonstrated the ability to decrease the risk of tumorigenesis and improve cancer therapy. There is increasing research on the origin and effects of pristine and doped TiO₂-based nanotherapeutic drugs. However, the detailed molecular mechanisms by which drug delivery to cancer cells alters sensing of gene mutations, protein degradation, and metabolite changes as well as its associated cumulative effects that determine the microenvironmental mechanosensitive metabolism have not yet been clearly elucidated. This review focuses on the microenvironmental influence of TiO₂-NPs induced various mechanical stimuli on tumor cells. The differential expression of genome, proteome, and metabolome after treatment with TiO₂-NPs is summarized and discussed. In the tumor microenvironment, mechanosensitive DNA mutations, gene delivery, protein degradation, inflammatory responses, and cell viability affected by the mechanical stimuli of TiO₂-NPs are also examined.

Ready player one? Autophagy shapes resistance to photodynamic therapy in cancers

Photodynamic therapy (PDT) is a procedure used in cancer therapy that has been shown to be useful for certain indications. Considerable evidence suggests that PDT might be superior to conventional modalities for some indications. In this report, we examine the relationship between PDT responsiveness and autophagy, which can exert a cytoprotective effect. Autophagy is an essential physiological process that maintains cellular homeostasis by degrading dysfunctional or impaired cellular components and organelles via a lysosome-based pathway. Autophagy, which includes macroautophagy and microautophagy, can be a factor that decreases or abolishes responses to various therapeutic protocols. We systematically discuss the mechanisms underlying cell-fate decisions elicited by PDT; analyse the principles of PDT-induced autophagy, macroautophagy and microautophagy; and present evidence to support the notion that autophagy is a critical mechanism in resistance to PDT. A combined strategy involving autophagy inhibitors may be able to further enhance PDT efficacy. Finally, we provide suggestions for future studies, note where our understanding of the relevant molecular regulators is deficient, and discuss the correlations among PDT-induced resistance and autophagy, especially microautophagy.

Anti-oxidant and Selective Anti-proliferative Effects of the Total Cornicabra Olive Polyphenols on Human Gastric MKN45 Cells

Background

According to the epidemiological studies, consuming olive products can decrease the incidence of the different types of cancers mostly due to the high anti-oxidant properties of their polyphenolic compounds.

Objectives

To evaluate the anti-oxidant and anti-proliferative potentials of the olive fruits total polyphenols on the gastric adenocarcinoma MKN45 cells in comparison to the normal Hu02 cells.

Materials and Methods

The total phenolic content of the olive fruits and radical scavenging activity were determined by Folin and 2,2-diphenyl-1-picrylhydrazyl (DPPH) tests respectively. MTT assay was performed for the evaluation of the cell viability. Intracellular reactive oxygen species (ROS) level was measured using DCFH-DA. Statistical analysis was performed using SPSS 16 statistical software.

Results

Treatment of the MKN45 cells with the phenolic compounds extracted from olive fruits decreased growth and viability of the cells in a dose- and time-dependent manner. In addition, treatment of the MKN45 cells with a combination of the phenolic compounds extracts and cytarabine further decreased cell compared to monotherapy of the cells with each compound alone. Mechanistically, we showed that the anti-cancer effects of the olive polyphenols in the MKN45 cells are mediated through depletion of ROS. Similarly, polyphenolic extracts were found to decrease ROS level in the normal cells at the concentrations of 500 and 1000 μg.mL^-1 and short treatment times (6 h), but the viability of these cells did not significantly change. At high concentrations (2000 μg.mL^-1) of the phenolic extracts or at longer times of incubation (12 h), however, both ROS levels and the viability of the cells were significantly decreased in the normal cells.

Conclusions

The olive fruits polyphenolic extract modulates ROS levels and selectively targets cancerous cells at low concentrations. Also, the effects of cytarabine could be potentiated by the olive fruits polyphenols. Thus, for a combined protocol of cancer cell therapy, olive fruit polyphenolic compound could be proposed as a proper candidate.