Nanoparticle-Mediated Mitochondrial Damage Induces Apoptosis in Cancer

CoCrMo nanoparticle induces neurotoxicity mediated via mitochondrial dysfunction: a study model for implant derived nanoparticle effects

Toxicity associated with elevated levels of cobalt-chromium-molybdenum (CoCrMo) nanoparticles in total hip replacement (THR) patients has been a rising concern. Recent investigations demonstrated that these particles can induce polyneuropathy in THR patients. The current study aims to address a detailed molecular investigation of CoCrMo nanoparticle-mediated mitochondrial dynamics using induced pluripotent stem cell-derived neurons (iPSC neurons). Telencephalic neurons from iPSCs were used in this study. A statistically significant dose-dependent reduction in membrane potential and mitochondrial superoxide generation was observed after CoCrMo nanoparticle treatment. The gene expression analysis confirmed that the oxidative-specific genes were significantly upregulated in particle-treated cells compared to untreated cells. When iPSCs were exposed to CoCrMo nanoparticles, there was a significant reduction in the area, perimeter, and length of mitochondria. Live cell imaging (mitochondrial tracking) revealed a significant reduction in mitochondrial movements in the presence of CoCrMo nanoparticles. Further protein expression confirmed increased mitochondrial fission in CoCrMo particle-treated cells by significantly upregulating Drp-1 protein and downregulating Mfn-2. In conclusion, the results show that CoCrMo nanoparticles can significantly alter neuronal mitochondrial dynamics. The disturbance in balance restricts mitochondrial movement, reduces energy production, increases oxidative stress, and can cause subsequent neurodegeneration.

Dog-bone shaped gold nanoparticle-mediated chemo-photothermal therapy impairs the powerhouse to trigger apoptosis in cancer cells

The mitochondrion has emerged as one of the uncommon targets in cancer therapeutics due to its involvement in cancer generation and progression. Consequently, nanoplatform mediated delivery of anti-cancer drugs into the mitochondria of cancer tissues demonstrated immense potential in cancer treatment. In the last couple of decades, gold nanoparticles have gained incredible attention in biomedical applications due to their easy synthesis, size-shape tenability, optical properties and outstanding photothermal ability. However, application of gold nanoparticles to target mitochondria to induce the chemo-photothermal effect in cancer has remained in its infancy. To address this, herein we have engineered dog-bone shaped gold nanoparticles (Mito-AuDB-NPs) comprising cisplatin and 10-hydroxycamptothecin as chemotherapeutic drugs along with the triphenylphosphonium (TPP) cation for mitochondria homing. Mito-AuDB-NPs exhibited a remarkable increase in temperature till 56 °C upon 18 min irradiation with 740 nm NIR LED light with a power density of 0.9 W cm-2. These Mito-AuDB-NPs successfully homed into the mitochondria of HeLa cervical cancer cells within 1 h and induced mitochondrial outer membrane permeabilization (MOMP) under the chemo-photothermal effect leading to the generation of reactive oxygen species (ROS). This Mito-AuDB-NP-mediated mitochondrial damage triggered programmed cell death (apoptosis) by decreasing the expression of anti-apoptotic Bcl-2/Bcl-xl and increasing the expression of pro-apoptotic BAX followed by caspase-3 cleavage towards extraordinary HeLa cell killing in a synergistic manner without showing toxicity towards non-cancerous RPE-1 human epithelial retinal pigment cells. We anticipate that this dog-bone shaped gold nanoparticle-mediated chemo-photothermal impairment of mitochondria in the cancer cells can open a new direction towards organelle targeted cancer therapy.

Enhanced cytotoxicity to lung cancer cells by mitochondrial delivery of camptothecin

Delivering traditional DNA-damaging anticancer drugs into mitochondria to damage mitochondria is a promising chemotherapy strategy. The impermeability of this mitochondrial inner membrane, however, impedes the delivery of drug molecules that could impact other important biological roles of mitochondria. Herein, the prodrug camptothecin (CPT)-triphenylphosphine (TPP) modified with hyaluronic acid (HA) via electrostatic adsorption (HA/CPT-TPP, HCT) was used to mediate the mitochondrial accumulation of CPT. These nanoparticles (NPs) showed enhanced drug accumulation in cancer cells through tumor targeting. HCT entered acidic lysosomes through endosomal transport, HA was degraded by hyaluronidase (HAase) in acidic lysosomes, and the positively charged CPT-TPP was exposed and accumulated fully in the mitochondria. Subsequently, CPT-TPP significantly disrupted the mitochondrial structure and damaged mitochondrial function, leading to increased reactive oxygen species (ROS) levels and energy depletion. Finally, HCT enhanced lung cancer cell apoptosis via the activation of caspase-3 and caspase-9. Furthermore, greatly increased tumor growth inhibition was observed in nude mice bearing A549 xenograft tumors after the administration of HCT via tail injection. This study demonstrated that the mitochondria-targeted delivery of CPT may be a promising antitumor therapeutic strategy.

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

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

Targeting Senescence as a Therapeutic Opportunity for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is associated with an elevated risk of recurrence and poor prognosis. Historically, only chemotherapy was available as systemic treatment, but immunotherapy and targeted therapies currently offer prolonged benefits. TNBC is a group of diseases with heterogeneous treatment sensitivity, and resistance is inevitable and early for a large proportion of the intrinsic subtypes. Although senescence induction by anticancer therapy offers an immediate favorable clinical outcome once the rate of tumor progression reduces, these cells are commonly dysfunctional and metabolically active, culminating in treatment-resistant repopulation associated with worse prognosis. This heterogeneous response can also occur without therapeutic pressure in response to damage or oncogenic stress, playing a relevant role in the carcinogenesis. Remarkably, there is preclinical and exploratory clinical evidence to support a relevant role of senescence in treatment resistance. Therefore, targeting senescent cells has been a scientific effort in many malignant tumors using a variety of targets and strategies, including increasing proapoptotic and decreasing antiapoptotic stimuli. Despite promising results, there are some challenges to applying this technology, including the best schedule of combination, assessment of senescence, specific vulnerabilities, and the best clinical scenarios. This review provides an overview of senescence in TNBC with a focus on future-proofing senotherapy strategies.

Label-Free Tracking of Nanoprodrug Cellular Uptake and Metabolism Using Raman and Autofluorescence Imaging

Nano-DDS, a drug delivery system using nanoparticles, is a promising tool to reduce adverse drug reactions and maximize drug efficiency. Understanding the intracellular dynamics following the accumulation of nanoparticles in tissues, such as cellular uptake, distribution, metabolism, and pharmacological effects, is essential to maximize drug efficiency; however, it remains elusive. In this study, we tracked the intracellular behavior of nanoparticles of a prodrug, cholesterol-linked SN-38 (CLS), in a label-free manner using Raman and autofluorescence imaging. Bright autofluorescent spots were observed in cells treated with CLS nanoparticles, and the color tone of the bright spots changed with incubation time. The Raman spectra of the bright spots showed that the autofluorescence came from the nanoparticles taken into cells, and the change in color of bright spots indicated that CLS turned into SN-38 via hydrolysis inside a cell. It was found that most of the SN-38 were localized in small regions in the cytoplasm even after the conversion from CLS, and only a small amount of SN-38 was dissolved and migrated into other cytoplasm regions and the nucleus. The massive size growth of cells was observed within several tens of hours after the treatment with CLS nanoparticles. Moreover, Raman images of cells using the cytochrome c band and the fluorescence images of cells stained with JC-1 showed that cellular uptake of CLS nanoparticles efficiently caused mitochondrial damage. These results show that the combination of Raman and autofluorescence imaging can provide insight into the intracellular behavior of prodrug nanoparticles and the cell response and facilitate the development of nano-DDSs.

Quantitative Measurement of Drug Release Dynamics within Targeted Organelles Using Förster Resonance Energy Transfer

Measuring the release dynamics of drug molecules after their delivery to the target organelle is critical to improve therapeutic efficacy and reduce side effects. However, it remains challenging to quantitatively monitor subcellular drug release in real time. To address the knowledge gap, a novel gemini fluorescent surfactant capable of forming mitochondria-targeted and redox-responsive nanocarriers is designed. A quantitative Förster resonance energy transfer (FRET) platform is fabricated using this mitochondria-anchored fluorescent nanocarrier as a FRET donor and fluorescent drugs as a FRET acceptor. The FRET platform enables real-time measurement of drug release from organelle-targeted nanocarriers. Moreover, the obtained drug release dynamics can evaluate the duration of drug release at the subcellular level, which established a new quantitative method for organelle-targeted drug release. This quantitative FRET platform can compensate for the absent assessment of the targeted release performances of nanocarriers, offering in-depth understanding of the drug release behaviors at the subcellular targets.

Mitochondrial-targeted nanoparticles: Delivery and therapeutic agents in cancer

Mitochondria are the powerhouses of cells and modulate the essential metabolic functions required for cellular survival. Various mitochondrial pathways, such as oxidative phosphorylation or production of reactive oxygen species (ROS) are dysregulated during cancer growth and development, rendering them attractive targets against cancer. Thus, the delivery of antitumor agents to mitochondria has emerged as a potential approach for treating cancer. Recent advances in nanotechnology have provided innovative solutions for overcoming the physical barriers posed by the structure of mitochondrial organelles, and have enabled the development of efficient mitochondrial nanoplatforms. In this review, we examine the importance of mitochondria during neoplastic development, explore the most recent smart designs of nano-based systems aimed at targeting mitochondria, and highlight key mitochondrial pathways in cancer cells.

Mitochondria-Targeting Polyprodrugs to Overcome the Drug Resistance of Cancer Cells by Self-Amplified Oxidation-Triggered Drug Release

The multi-drug resistance (MDR) of cancers is one of the main barriers for the success of diverse chemotherapeutic methods and is responsible for most cancer deaths. Developing efficient approaches to overcome MDR is still highly desirable for efficient chemotherapy of cancers. The delivery of targeted anticancer drugs that can interact with mitochondrial DNA is recognized as an effective strategy to reverse the MDR of cancers due to the relatively weak DNA-repairing capability in the mitochondria. Herein, we report on a polyprodrug that can sequentially target cancer cells and mitochondria using folic acid (FA) and tetraphenylphosphonium (TPP) targeting moieties, respectively. They were conjugated to the terminal groups of the amphiphilic block copolymer prodrugs composed of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) and copolymerized monomers containing cinnamaldehyde (CNM) and doxorubicin (DOX). After self-assembly into micelles with the suitable size (∼30 nm), which were termed as TF@CNM + DOX, and upon intravenous administration, the micelles can accumulate in tumor tissues. After FA-mediated endocytosis, the endosomal acidity (∼pH 5) can trigger the release of CNM from TF@CNM + DOX micelles, followed by enhanced accumulation into the mitochondria via the TPP target. This promotes the overproduction of reactive oxygen species (ROS), which can subsequently enhance the intracellular oxidative stress and trigger ROS-responsive release of DOX into the mitochondria. TF@CNM + DOX shows great potential to inhibit the growth of DOX-resistant MCF-7 ADR tumors without observable side effects. Therefore, the tumor and mitochondria dual-targeting polyprodrug design represents an ideal strategy to treat MDR tumors through improvement of the intracellular oxidative level and ROS-responsive drug release.

Glutathione improves testicular spermatogenesis through inhibiting oxidative stress, mitochondrial damage, and apoptosis induced by copper deposition in mice with Wilson disease

BACKGROUND AND OBJECTIVE

There are considerable evidence of reproductive impairment in male organisms with Wilson disease (WD). The purpose of this study was to observe spermatogenesis, mitochondrial damage, apoptosis, and the level of oxidative stress in the testes of Wilson disease model TX mice, and to observe the effect and mechanism of glutathione on testicular spermatogenesis.

METHODS

Mice were divided into a normal control group (control group), Wilson disease model TX mice group (WD group), penicillamine-treated TX mice group (penicillamine group) and glutathione-treated TX mice group (glutathione group). Testicular coefficient, histomorphology of testis and epididymis, number of spermatozoa, apoptosis of spermatogenic cells and expression of apoptosis-related proteins were observed. Ultrastructural analysis of mitochondria and mitochondrial membrane potential (MMP) monitored using JC-1 dye were used to detect mitochondrial damage. The levels of malondialdehyde (MDA), glutathione (GSH), catalase (CAT), and reactive oxygen species (ROS) in testicular cells were measured to assess oxidative stress.

RESULTS

Testicular coefficient did not change in mice with Wilson disease. However, the tissue structure of the testicular seminiferous tubules was damaged, and the number of spermatozoa in the epididymal lumen was significantly reduced in WD group. The apoptosis rate in the testes was significantly increased. The protein expression of the pro-apoptotic proteins Bax and Caspase-3 significantly increased, and the expressions of the anti-apoptotic protein Bcl-2 significantly decreased. The levels of ROS and MDA significantly increased, and the levels of CAT and GSH significantly decreased. Mitochondria with abnormal ultrastructure and the rate of JC-1 positive cells were significantly increased in the WD group. After copper chelation by penicillamine, the structure of the testicular seminiferous tubules and the number of spermatozoa in the epididymal lumen were significantly improved. The number of apoptotic cells was significantly reduced. The levels of Bax and Caspase-3 decreased, and the expression of Bcl-2 increased. The contents of CAT and GSH increased, and the levels of ROS and MDA decreased significantly. The abnormal mitochondria and JC-1 positive cells was significantly decreased. The histomorphology of seminiferous tubules, spermatogenic function, apoptosis rate, apoptosis-related proteins, mitochondrial damage, and oxidative stress in Wilson disease TX mice significantly improved after glutathione treatment.

CONCLUSION

Copper deposition in Wilson disease can lead to oxidative stress injury, mitochondrial damage, and apoptosis in the testis, leading to the impairment of spermatogenesis. Glutathione may improve testicular spermatogenesis in male Wilson disease TX mice by inhibiting copper deposition-induced oxidative stress, mitochondrial damage, and apoptosis.

Morphological Transformation and In Situ Polymerization of Caspase-3 Responsive Diacetylene-Containing Lipidated Peptide Amphiphile for Self-Amplified Cooperative Antitumor Therapy

In order to artificially regulate cell behaviors, intracellular polymerization as an emerging chemical technique has attracted much attention. Yet, it is still a challenge to achieve effective intracellular polymerization to conquer tumors in the complex cellular environment. Herein, this work develops a tumor-targeting and caspase-3 responsive nanoparticle composed of a diacetylene-containing lipidated peptide amphiphile and mitochondria-targeting photosensitizer (C3), which undergoes nanoparticle-to-nanofiber transformation and efficient in situ polymerization triggered by photodynamic treatment and activation of caspase-3. The locational nanofibers on the mitochondria membranes lead to mitochondrial reactive oxygen species (mtROS) burst and self-amplified circulation, offering persistent high oxidative stress to induce cell apoptosis. This study provides a strategy for greatly enhanced antitumor therapeutic efficacy through mtROS burst and self-amplified circulation induced by intracellular transformation and in situ polymerization.

A mitochondria-targeted nano-platform for pancreatic cancer therapy

Liposome is a conventional drug delivery system which has been widely used in the pharmacy field. However, its applications are greatly restricted in clinical practice by the disadvantages of cholesterol and nonselective distribution. Herein, a novel platform for anti-tumor drug delivery was developed by incorporating an amphiphilic stachydrine-octadecane conjugate (SS) as the mitochondria-targeting molecule onto the triptolide-liposome surfaces (SS-TP LPs). The polyethylene glycol (PEG) and the suitable particle size (about 133 nm) of liposomes facilitated their stabilities, the long half-life in blood and the escape from the rapid elimination. The SS-TP LPs were internalized and accumulated into the mitochondria of cancer cells in a time-dependent manner, followed by triggering permeabilization of the mitochondrial outer membrane by inhibiting Bcl-2, and then further caused greater cancer cell death via releasing cytochrome C and initiating a cascade of caspase 3 reactions. In the Pan02 tumor-bearing mice, the SS-TP LPs showed significant efficacy in inhibiting tumor growth and reducing tumor size but synchronously exhibited specific mitochondria-targeting and much lower subacute toxicity compared with the free TP and TP LPs. Our study suggests that SS-TP LPs can be a promising anticancer drug delivery system for mitochondria-targeted therapy in pancreatic cancer.

Apple pectin-based Zataria multiflora essential oil (ZEO) nanoemulsion: An approach to enhance ZEO DNA damage induction in breast cancer cells as in vitro and in silico studies reveal

Zataria multiflora essential oil (ZEO) is a natural complex of compounds with a high apoptotic potential against breast cancer cells and minor toxicity toward normal cells; however, similar to many essential oils, ZEO utilization in pharmaceutical industries has limitations due to its labile and sensitive ingredients. Nanoemulsification based on natural polymers is one approach to overcome this issue. In this study, an apple pectin-ZEO nanoemulsion (AP-ZEONE) was prepared and its morphology, FTIR spectra, and physical properties were characterized. Furthermore, it was shown that AP-ZEONE substantially suppresses the viability of MDA-MB-231, T47D, and MCF-7 breast cancer cells. AP-ZEONE significantly induced apoptotic morphological alterations and DNA fragmentation as confirmed by fluorescent staining and TUNEL assay. Moreover, AP-ZEONE induced apoptosis in MDA-MB-231 cells by loss of mitochondrial membrane potential (ΔΨm) associated with the accumulation of reactive oxygen species (ROS), G2/M cell cycle arrest, and DNA strand breakage as flow cytometry, DNA oxidation, and comet assay analysis revealed, respectively. Spectroscopic and computational studies also confirmed that AP-ZEONE interacts with genomic DNA in a minor groove/partial intercalation binding mode. This study demonstrated the successful inhibitory effect of AP-ZEONE on metastatic breast cancer cells, which may be beneficial in the therapy process.

Mitochondrial Genetic and Epigenetic Regulations in Cancer: Therapeutic Potential

Mitochondria are dynamic organelles managing crucial processes of cellular metabolism and bioenergetics. Enabling rapid cellular adaptation to altered endogenous and exogenous environments, mitochondria play an important role in many pathophysiological states, including cancer. Being under the control of mitochondrial and nuclear DNA (mtDNA and nDNA), mitochondria adjust their activity and biogenesis to cell demands. In cancer, numerous mutations in mtDNA have been detected, which do not inactivate mitochondrial functions but rather alter energy metabolism to support cancer cell growth. Increasing evidence suggests that mtDNA mutations, mtDNA epigenetics and miRNA regulations dynamically modify signalling pathways in an altered microenvironment, resulting in cancer initiation and progression and aberrant therapy response. In this review, we discuss mitochondria as organelles importantly involved in tumorigenesis and anti-cancer therapy response. Tumour treatment unresponsiveness still represents a serious drawback in current drug therapies. Therefore, studying aspects related to genetic and epigenetic control of mitochondria can open a new field for understanding cancer therapy response. The urgency of finding new therapeutic regimens with better treatment outcomes underlines the targeting of mitochondria as a suitable candidate with new therapeutic potential. Understanding the role of mitochondria and their regulation in cancer development, progression and treatment is essential for the development of new safe and effective mitochondria-based therapeutic regimens.

Green synthesis of DOX-loaded hollow MIL-100 (Fe) nanoparticles for anticancer treatment by targeting mitochondria

Fe-based Metal-Organic Frameworks (MOFs) are promising drug delivery materials due to their large surface area, high stability, and biocompatibility. However, their drug loading capacity is constrained by their small pore size, and a further improvement in their drug capacity is needed. In this work, we report an effective and green structural modification strategy to improve drug loading capacity for Fe-based MOFs. Our strategy is to grow MIL-100 (Fe) on carboxylate-terminated polystyrene (PS-COOH) via a sustainable route, which creates a large inner cavity as well as exposure of more functional groups that benefit drug loading capacity. We perform the scanning electron microscope and transmission electron microscope to confirm the hollow structure of MIL-100 (Fe). Up to 30% of drug loading capacity has been demonstrated in our study. We also conduct cell viability tests to investigate its therapeutic effects on breast cancer cells (MDA-MB-231). Confocal laser scanning microscopy imaging confirms cellular uptake and mitochondrial targeting function of doxorubicin-loaded H-M (DOX@H-M) nanoparticles. JC-1 staining of cancer cells reveals a significant change in the mitochondrial membrane potential, indicating the mitochondrial dysfunction and apoptosis of tumor cells. Our study paves the way for facile synthesis of hollow structural MOFs, and demonstrates the potential of applying Fe-based MOFs in breast cancer treatment.

Silver Nanoparticles Induce Apoptosis in HepG2 Cells through Particle-Specific Effects on Mitochondria

Silver nanoparticles (AgNPs) have been widely used in biomedical and consumer products. It remains challenging to distinguish the toxicity of AgNPs derived from the particle form or the released silver ions (Ag⁺). In this study, the toxic effects of two citrate-coated AgNPs (20 and 100 nm) and Ag⁺ were investigated in hepatoblastoma cells (HepG2 cells). The suppression tests showed that AgNPs and Ag⁺ induced cell apoptosis via different pathways, which led us to speculate on the AgNP-induced mitochondrial damage. Then, the mitochondrial damages induced by AgNPs and Ag⁺ were compared under the same intracellular Ag⁺ concentration, showing that the mitochondrial damage might be mainly attributed to Ag nanoparticles but not to Ag⁺. The interaction between AgNPs and mitochondria was analyzed using a scattered light imaging method combined with light intensity profiles and transmission electron microscopy. The colocalization of AgNPs and mitochondria was observed in both NP20- and NP100-treated HepG2 cells, indicating a potential direct interaction between AgNPs and mitochondria. These results together showed that AgNPs induced apoptosis in HepG2 cells through the particle-specific effects on mitochondria.

Chimeric nanoparticles for targeting mitochondria in cancer cells

Mitochondrial dysfunction is implicated in myriad diseases, including cancer. Subsequently, targeting mitochondrial DNA (mt-DNA) in cancer cells has emerged as an unorthodox strategy for anti-cancer therapy. However, approaches targeting only one component of the mitochondrial "central dogma" can be evaded by cancer cells through various mechanisms. To address this, herein, we have engineered mitochondria-targeting cholesterol-based chimeric nanoparticles (mt-CNPs) consisting of cisplatin, camptothecin, and tigecycline, which can simultaneously impair mt-DNA, mitochondrial topoisomerase I (mt-Top1), and mitochondrial ribosomes. mt-CNPs were characterized as being positively charged, spherical in shape, and 187 nm in diameter. Confocal microscopy confirmed that mt-CNPs efficiently localized into the mitochondria of A549 lung cancer cells within 6 h, followed by mitochondrial morphology damage and the subsequent generation of reactive oxygen species (ROS). mt-CNPs showed remarkable cancer-cell killing abilities compared to free-drug combinations in A549 (lung), HeLa (cervical), and MCF7 (breast) cancer cells. These mitochondria-targeting lipidic chimeric nanoparticles could be explored further to impair multiple targets in mitochondria, helping researchers to gain an understanding of mitochondrial translational and transcriptional machinery and to develop new strategies for cancer therapy.

Dose-Dependent Molecular Responses of Labeo rohita to Triphenyl Phosphate

Triphenyl phosphate (TPhP) is a broad-spectrum organophosphate compound widely used as an additive in several products to prevent ignition. However, its utilization produces a hazardous impact on various organisms. So far, very few studies have investigated the acute toxicity of TPhP at environmentally relevant concentrations in nontarget aquatic species. This study aimed to assess whether the short-term exposure of TPhP (4, 20, and 100 μg L^-1) affects the oxidative stress, antioxidant activity, biomolecule metabolism, DNA stability, chromosomal integrity, apoptosis, and pathological changes in various organs of Labeo rohita fingerlings. The results illustrated that the reactive oxygen species (ROS) production and lipid peroxidation (LPO) rates were significantly higher in tissues (brain, liver, and kidney) of TPhP-treated groups. Interestingly, superoxide dismutase (SOD) and catalase (CAT) activities were remarkably decreased in tissues following TPhP exposure. The levels of protein, glucose, total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) in various tissues were also found to be significantly altered in TPhP-exposed fish fingerlings. These significant alterations in the antioxidant system and biochemical profile induced genotoxic responses such as DNA and chromosomal damage in the fish fingerlings. Furthermore, the incidence of the observed genotoxic responses was also found to be dose-dependent. Likewise, the apoptotic responses were also significantly altered following TPhP acute exposure in L. rohita fingerlings. The subsequent effects on oxidative stress, antioxidant inhibition, dysregulated biomolecule metabolism, and genotoxicity might be the possible reason for the observed pathological changes in various tissues of L. rohita. Taken together, the present findings showed that the toxicity of TPhP is principally associated with exposure concentrations. Therefore, this study illustrates the toxicity risks of TPhP to vertebrate organisms at real-world concentrations.

Iridium(III)-BBIP complexes induce apoptosis via PI3K/AKT/mTOR pathway and inhibit A549 lung tumor growth in vivo

The new ligand BBIP (BBIP = 2-(7-bromo-2H-benzo[d]imidazole-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) with its iridium(III) complexes: [Ir(ppy)2(BBIP)](PF6) (ppy = 2-phenylpyridine, Ir1), [Ir(bzq)2(BBIP)](PF6) (bzq = benzo[h]quinolone, Ir2) and [Ir(piq)2(BBIP)](PF6) (piq = 1-phenylisoquinoline, Ir3) were synthesized and characterized by elemental analysis, High Resolution Mass Spectrometer (HRMS), 1H NMR and 13C{1H} NMR. The cytotoxicity of the complexes against A549, HepG2, SGC-7901, BEL-7402, HeLa and normal LO2 was evaluated through 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. The results show that Ir1 exhibits high cytotoxic activity against A549 cells with a low IC50 value of 4.9 ± 0.5 μM. A series of biological activities such as cell cycle arrest, endoplasmic reticulum localization assay, apoptosis, western blotting, cellular uptake determination and in vivo antitumor activity were investigated. The assays implied that the complexes inhibit cancer cell migration through blocking mitotic progress. Cell cycle distribution stated that the complexes depress cell growth at G0/G1 phase. Additionally, the complexes acted on the endoplasmic reticulum and induce apoptosis through endoplasmic reticulum stress pathway. Especially, the western blotting showed that the complexes activated Bcl-2 (B-cell lymphoma-2) family and decreased PI3K (phosphoinositide-3 kinase) and AKT (protein kinase B), up-regulated the expression of mTOR (mammalian target of rapamycin) and p-mTOR (phosphorylated mammalian target of rapamycin). Therefore, the complexes induce apoptosis through activating PI3K-AKT-mTOR pathway. Antitumor in vivo demonstrated that Ir1 can effectively prevent the tumor growth with an inhibitory rate of 48.89%.

Nanoparticle-Mediated Routing of Antibiotics into Mitochondria in Cancer Cells

In recent years, antibiotics have emerged as alternative medicines in cancer therapy due to their capability of mitochondrial dysfunction in cancer cells. However, antibiotics render collateral damage in noncancerous cells by targeting mitochondrial transcription and translational machinery. To address this, herein, we have engineered three different mitochondria-targeted cationic antibiotic (tigecycline)-loaded nanoparticles from cholesterol conjugates. Dynamic light scattering and electron microscopy confirmed the spherical morphology and a less than 200 nm hydrodynamic diameter for these nanoparticles. The triphenylphosphine-coated tigecycline-loaded nanoparticle (Mito-TPP-Tig-NP) was shown to be homed into the mitochondria of A549 lung cancer cells compared to the other cationic nanoparticles. These Mito-TPP-Tig-NPs indeed triggered mitochondrial morphology damage and generation of reactive oxygen species (ROS). All the mitochondria-targeted tigecycline-loaded nanoparticles showed improved cancer cell killing ability in A549 and HeLa cervical cancer cells compared to free tigecycline. Moreover, Mito-TPP-Tig-NPs showed much less toxicity toward noncancerous human embryonic kidney cells (HEK293) compared to free tigecycline. These antibiotic-loaded mitochondria-targeted nanoparticles can open up an avenue toward anticancer therapy.

Targeted Mitochondrial Fluorescence Imaging-Guided Tumor Antimetabolic Therapy with the Imprinted Polymer Nanomedicine Capable of Specifically Recognizing Dihydrofolate Reductase

As we all know, inhibiting the activity of dihydrofolate reductase (DHFR) has always been an effective strategy for folate antimetabolites to treat tumors. In the past, it mainly relied on chemical drugs. Here, we propose a new strategy, (3-propanecarboxyl)triphenylphosphonium bromide (CTPB)-modified molecularly imprinted polymer nanomedicine (MIP-CTPB). MIP-CTPB prepared by imprinting the active center of DHFR can specifically bind to the active center to block the catalytic activity of DHFR, thereby inhibiting the synthesis of DNA and ultimately inhibiting the tumor growth. The modification of CTPB allows the nanomedicine to be targeted and enriched in mitochondria, where DHFR is abundant. The confocal laser imaging results show that MIP-CTPB can target mitochondria. Cytotoxicity experiments show that MIP-CTPB inhibits HeLa cell proliferation by 42.2%. In vivo experiments show that the tumor volume of the MIP-CTPB-treated group is only one-sixth of that of the untreated group. The fluorescent and paramagnetic properties of the nanomedicine enable targeted fluorescence imaging of mitochondria and T2-weighted magnetic resonance imaging of tumors. This research not only opens up a new direction for the application of molecular imprinting, but also provides a new idea for tumor antimetabolic therapy guided by targeted mitochondrial imaging.

Synthesis and evaluation of iridium(III) complexes on antineoplastic activity against human gastric carcinoma SGC-7901 cells

The study was intended to determine the antineoplastic effects of two new iridium(III) complexes [Ir(ppy)₂(PTTP)](PF₆) (1) (ppy = 2-phenylpyridine) and [Ir(piq)₂(PTTP)](PF₆) (2) (piq = 1-phenylisoquinoline, PTTP = 2-phenoxy-1,4,8,9-tetraazatriphenylene). In MTT assay, the ligand PTTP displayed ineffective inhibition on cell growth in SGC-7901, BEL-7402, HepG2 as well as NIH3T3 cell lines, while complexes 1 and 2 showed high cytotoxic activity on SGC-7901 cells with an IC₅₀ value of 0.5 ± 0.1 µM and 4.4 ± 0.6 µM, respectively. Cellular uptake, cell cloning experiments, wound healing assay and cell cycle arrest indicated that the two complexes can inhibit the cell proliferation in SGC-7901 and induce cell cycle arrest at G0/G1 phase. Additionally, reactive oxygen species (ROS) and mitochondrial membrane potential suggested that the two complexes induced cell apoptosis through disrupting mitochondrial functions. Further, western blot analysis illustrated that the two complexes caused apoptosis via regulating expression levels of Bcl-2 family proteins. Moreover, complex 1 could suppress tumor growth in vivo with an inhibitory rate of 49.41%. Altogether, these results demonstrated that complexes 1 and 2 exert a potent anticancer effect against SGC-7901 cells via mitochondrial apoptotic pathway and have a potential to be developed as antineoplastic drug candidates for human gastric cancer.

Mitochondria-acting carrier-free nanoplatform self-assembled by α-tocopheryl succinate carrying cisplatin for combinational tumor therapy

Unsatisfactory drug loading capability, potential toxicity of the inert carrier and the limited therapeutic effect of a single chemotherapy drug are all vital inhibitory factors of carrier-assisted drug delivery systems for chemotherapy. To address the above obstacles, a series of carrier-free nanoplatforms self-assembled by dual-drug conjugates was constructed to reinforce chemotherapy against tumors by simultaneously disrupting intratumoral DNA activity and inhibiting mitochondria function. In this nanoplatform, the mitochondria-targeting small-molecular drug, α-tocopheryl succinate (TOS), firstly self-assembled into nanoparticles, which then were used as the carrier to conjugate cisplatin (CDDP). Systematic characterization results showed that this nanoplatform exhibited suitable particle size and a negative surface charge with good stability in physicochemical environments, as well as pH-sensitive drug release and efficient cellular uptake. Due to the combined effects of reactive oxygen species (ROS) generation by TOS and DNA damage by CDDP, the developed nanoplatform could induce mitochondrial dysfunction and elevated cell apoptosis, resulting in highly efficient anti-tumor outcomes in vitro. Collectively, the combined design principles adopted for carrier-free nanodrugs construction in this study aimed at targeting different intracellular organelles for facilitating ROS production and DNA disruption can be extended to other carrier-free nanodrugs-dependent therapeutic systems.

Mitochondria-targeted vitamin E succinate delivery for reversal of multidrug resistance

Inducing mitochondrial malfunction is an appealing strategy to overcome tumor multidrug resistance (MDR). Reported here a versatile mitochondrial-damaging molecule, vitamin E succinate (VES), is creatively utilized to assist MDR reversal of doxorubicin hydrochloride (DOX·HCl) via a nanovesicle platform self-assembled from amphiphilic polyphosphazenes containing pH-sensitive 1H-benzo-[d]imidazol-2-yl) methanamine (BIMA) groups. Driven by multiple non-covalent interactions, VES is fully introduced into the hydrophobic membrane of DOX·HCl-loaded nanovesicles with loading content of 23.5%. The incorporated VES also offers robust anti-leakage property toward DOX·HCl under normal physiological conditions. More importantly, upon release within acidic tumor cells, VES can target mitochondria and result in various dysfunctions including excessive generation of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨ_m) loss, and inhibited adenosine triphosphate (ATP) synthesis, which contribute to cell apoptosis and insufficient energy supply for drug efflux pumps. Consequently, the killing-effect of DOX·HCl is significantly enhanced toward drug resistant cancer cells at the optimal mass ratio of DOX·HCl to VES. Further in vivo antitumor investigation on nude mice bearing xenograft drug-resistant human chronic myelogenous leukemia K562/ADR tumors verifies the extremely enhanced anti-tumor efficacy of the dual drug-loaded nanovesicle with the tumor inhibition rate (TIR) of 82.38%. Collectively, this study provides a s safe, facile and promising strategy for both precise drug delivery and MDR eradication to improve cancer therapy.

Cisplatin and paclitaxel co-delivery nanosystem for ovarian cancer chemotherapy

We have designed and developed an effective drug delivery system using biocompatible polymer of poly (ethylene glycol)-polyaspartic acid (mPEG-PAsp) for co-loading the chemotherapy drugs paclitaxel (PTX) and cisplatin (CP) in one nano-vehicle. This study aimed to improve the anti-cancer efficacy of combinations of chemotherapy drugs and reduce their side effects. mPEG-PAsp-(PTX/Pt) nano-micelles disperse well in aqueous solution and have a narrow size distribution (37.8 ± 3.2 nm) in dynamic light scattering (DLS). Drug release profiles found that CP released at pH 5.5 was significantly faster than that at pH 7.4. MPEG-PAsp-(PTX/Pt) nano-micelles displayed a significantly higher tumor inhibitory effect than mPEG-PAsp-PTX nano-micelles when the polymer concentrations reached 50 μg/mL. Our data indicated that polymer micelles of mPEG-PAsp loaded with the combined drug exert synergistic anti-tumor efficacy on SKOV3 ovarian cells via different action mechanisms. Results from our studies suggested that mPEG-PAsp-(PTX/Pt) nano-micelles are promising alternatives for carrying and improving the delivery of therapeutic drugs with different water solubilities.

pH-activated, mitochondria-targeted, and redox-responsive delivery of paclitaxel nanomicelles to overcome drug resistance and suppress metastasis in lung cancer

Background

Mitochondria play a role in the occurrence, development, drug resistance, metastasis, and other functions of cancer and thus are a drug target. An acid-activated mitochondria-targeting drug nanocarrier with redox-responsive function was constructed in the present study. However, whether this vector can precisely delivery paclitaxel (PTX) to enhance therapeutic efficacy in drug-resistant lung cancer is unknown.

Results

Acid-cleavable dimethylmaleic anhydride (DA) was used to modify pluronic P85-conjugated mitochondria-targeting triphenylphosphonium (TPP) using disulfide bonds as intermediate linkers (DA-P85-SS-TPP and DA-P-SS-T). The constructed nanocarriers demonstrated enhanced cellular uptake and selective mitochondrial targeting at extracellular pH characteristic for a tumor (6.5) and were characterized by extended circulation in the blood. TPP promoted the targeting of the DA-P-SS-T/PTX nanomicelles to the mitochondrial outer membrane to decrease the membrane potential and ATP level, resulting in inhibition of P-glycoprotein and suppression of drug resistance and cancer metastasis. PTX was also rapidly released in the presence of high glutathione (GSH) levels and directly diffused into the mitochondria, resulting in apoptosis of drug-resistant lung cancer cells.

Conclusions

These promising results indicated that acid-activated mitochondria-targeting and redox-responsive nanomicelles potentially represent a significant advancement in cancer treatment.

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Mucin corona delays intracellular trafficking and alleviates cytotoxicity of nanoplastic-benzopyrene combined contaminant

Nanoplastics have recently become a worldwide concern as newly emerging airborne pollutants, which can associate with polycyclic aromatic hydrocarbons (PAHs) and form combined contaminant nanoparticles (CCNPs). After being inhaled in the respiratory system, the CCNPs would first encounter the mucous gel layer being rich in mucin. Herein, polystyrene-benzopyrene (PS@Bap) NPs were prepared as CCNPs model and their interaction with mucin and the resultant biological responses were studied. It was observed that mucin corona stably attached to the CCNPs surface, which significantly altered the fate of the CCNPs in lung epithelial cells (A 549 cell line). The mucin corona would 1) stably adsorbed on PS@Bap at the early stages of endocytosis until degraded during the lysosomal transport and maturation process, 2) delay intracellular trafficking of PS@Bap and the progress of Bap detached from PS, 3) enhance uptake of PS@Bap but reduce the cytotoxicity elicited by PS@Bap, as indicated by cell viability, generation of reactive oxygen species, impairment on mitochondrial function, and further cell apoptosis. In addition, in vivo study also verified the enhanced effect of PS on the development of an acute lung inflammatory response induced by Bap. This study highlights the significance of incorporating the effects of mucin for precisely assessing the respiratory system toxicity of nanoplastics based CCNPs in atmospheric environments.

Surmounting tumor resistance to metallodrugs by co-loading a metal complex and siRNA in nanoparticles

Copper complexes are promising anticancer agents widely studied to overcome tumor resistance to metal-based anticancer drugs. Nevertheless, copper complexes per se encounter drug resistance from time to time. Adenosine-5'-triphosphate (ATP)-responsive nanoparticles containing a copper complex CTND and B-cell lymphoma 2 (Bcl-2) small interfering RNA (siRNA) were constructed to cope with the resistance of cancer cells to the complex. CTND and siRNA can be released from the nanoparticles in cancer cells upon reacting with intracellular ATP. The resistance of B16F10 melanoma cells to CTND was terminated by silencing the cellular Bcl-2 gene via RNA interference, and the therapeutic efficacy was significantly enhanced. The nanoparticles triggered a cellular autophagy that amplified the apoptotic signals, thus revealing a novel mechanism for antagonizing the resistance of copper complexes. In view of the extensive association of Bcl-2 protein with cancer resistance to chemotherapeutics, this strategy may be universally applicable for overcoming the ubiquitous drug resistance to metallodrugs.

Endocytosis and Organelle Targeting of Nanomedicines in Cancer Therapy

Nanomedicines (NMs) have played an increasing role in cancer therapy as carriers to efficiently deliver therapeutics into tumor cells. For this application, the uptake of NMs by tumor cells is usually a prerequisite to deliver the cargo to intracellular locations, which mainly relies on endocytosis. NMs can enter cells through a variety of endocytosis pathways. Different endocytosis pathways exhibit different intracellular trafficking routes and diverse subcellular localizations. Therefore, a comprehensive understanding of endocytosis mechanisms is necessary for increasing cellular entry efficiency and to trace the fate of NMs after internalization. This review focuses on endocytosis pathways of NMs in tumor cells, mainly including clathrin- and caveolae-mediated endocytosis pathways, involving effector molecules, expression difference of those molecules between normal and tumor cells, as well as the intracellular trafficking route of corresponding endocytosis vesicles. Then, the latest strategies for NMs to actively employ endocytosis are described, including improving tumor cellular uptake of NMs by receptor-mediated endocytosis, transporter-mediated endocytosis and enabling drug activity by changing intracellular routes. Finally, active targeting strategies towards intracellular organelles are also mentioned. This review will be helpful not only in explicating endocytosis and the trafficking process of NMs and elucidating anti-tumor mechanisms inside the cell but also in rendering new ideas for the design of highly efficacious and cancer-targeted NMs.

Precise design strategies of nanomedicine for improving cancer therapeutic efficacy using subcellular targeting

Therapeutic efficacy against cancer relies heavily on the ability of the therapeutic agents to reach their final targets. The optimal targets of most cancer therapeutic agents are usually biological macromolecules at the subcellular level, which play a key role in carcinogenesis. Therefore, to improve the therapeutic efficiency of drugs, researchers need to focus on delivering not only the therapeutic agents to the target tissues and cells but also the drugs to the relevant subcellular structures. In this review, we discuss the most recent construction strategies and release patterns of various cancer cell subcellular-targeting nanoformulations, aiming at providing guidance in the overall design of precise nanomedicine. Additionally, future challenges and potential perspectives are illustrated in the hope of enhancing anticancer efficacy and accelerating the translational progress of precise nanomedicine.

Rational Construction of a Mitochondrial Targeting, Fluorescent Self-Reporting Drug-Delivery Platform for Combined Enhancement of Endogenous ROS Responsiveness

To maximize the utilization and response to the high oxidative stress environment of tumor sites while avoiding the dilemma of enhancing reactive oxygen species (ROS) response in a single way, mitochondrial targeting combined with fluorescent self-reporting polymeric nanocarriers (1K-TPP and 2K-TPP) with grafted structures were synthesized via a chemoenzymatic method in a high yield to simultaneously enhance the drug delivery of endogenous ROS responses. 1K-TPP and 2K-TPP loaded doxorubicin (DOX) at a high content over 12% and formed homogeneous spherical micelles. In vitro, both of them showed promising high sensitivity (detection limit below 200 nM H₂O₂), fast response, and ratiometric fluorescent self-reporting properties (fluorescent enhancement more than 200 times) to ROS and excellent stability under physiological conditions, while achieving a rapid release of the DOX in response to 1 mM H₂O₂. Cell co-localization experiments exhibited that they had favorable mitochondrial targeting, and mitochondrial isolation experiments also confirmed that the TPP-modified 1K-TPP selectively accumulated nearly three times in mitochondria than that in total cells. The internalization of 1K-TPP and 2K-TPP into cancer cells was greatly improved by nearly 200% compared to that of unmodified control (1K-OH and 2K-OH) and also explored a unique energy-dependent endocytosis. Furthermore, stimulation of endogenous ROS enhanced the green fluorescence intensity (up to 51.4%) of the linked probe so as to destroy the internal structure of the nanocarriers, achieving self-reporting of the drug's intracellular release and tracking of the intracellular location of nanocarriers. The cytotoxicity of DOX-loaded 1K-TPP and 2K-TPP in tumor cells with a higher ROS content showed statistical superiority to that of 1K-OH and 2K-OH, benefiting from the extremely good endogenous ROS response sensitivity leading to the differential selective release of drugs. These results demonstrate the potential of 1K-TPP and 2K-TPP, especially for 1K-TPP, as mitochondria-targeted, fluorescent self-reporting nanocarriers for combined enhancement of endogenous ROS responsiveness.

Targeted and Intrinsic Activity of HA-Functionalized PEI-Nanoceria as a Nano Reactor in Potential Triple-Negative Breast Cancer Treatment

Although there has been considerable achievement in the field of breast cancer therapeutics, tackling the disturbing issue of highly potent triple-negative breast cancer (TNBC) still remains a hurdle in cancer therapeutics. Here, for the first time we propose a poly(ethylenimine) (PEI)-mediated approach for the synthesis of hyaluronic acid (HA) tagged cerium oxide nanoparticles (CePEI-NPs) as a therapeutic agent in TNBC. Primarily, the formulated HA-CePEI-NPs upon treatment displayed superior anticancer effect by exhibiting the loss of mitochondrial membrane potential (MMP). These particles acted as a nano reactor by the generation of reactive oxygen species (ROS) during the treatment. We further evaluated the caspase activity which divulgated the activation of caspases-3 and -9 while there was a decrease in the level of Bcl-2. The treatment also resulted in the release of cytochrome c (Cyt c), and in addition, features such as pynknosis and G2/M phase arrest were also noted. Hence the nano reactor property of nano ceria in activating mitochondrial-mediated intrinsic apoptosis highlights its promising role as a nano drug for therapeutic applications in TNBC.

Mitochondrial Impairment by Cyanine-Based Small Molecules Induces Apoptosis in Cancer Cells

Mitochondrion, the powerhouse of the cells, has emerged as one of the unorthodox targets in anticancer therapy due to its involvement in several cellular functions. However, the development of small molecules for selective mitochondrial damage in cancer cells remained limited and less explored. To address this, in our work, we have synthesized a natural product inspired cyanine-based 3-methoxy pyrrole small molecule library by a concise strategy. This strategy involves Vilsmeier and Pd(0) catalyzed Suzuki cross-coupling reactions as key steps. The screening of the library members in HeLa cervical cancer cells revealed two new molecules that localized into subcellular mitochondria and damaged them. These small molecules perturbed antiapoptotic (Bcl-2/Bcl-xl) and pro-apoptotic (Bax) proteins to produce reactive oxygen species (ROS). Molecular docking studies showed that both molecules bind more tightly with the BH3 domain of Bcl-2 proteins compared to obatoclax (a pan-Bcl-2 inhibitor). These novel small molecules arrested the cell cycle in the G0/G1 phase, cleaved caspase-3/9, and finally prompted late apoptosis. This small molecule-mediated mitochondrial damage induced remarkably high cervical cancer cell death. These unique small molecules can be further explored as chemical biology tools and next-generation organelle-targeted anticancer therapy.

Silver nanoparticles modulate mitochondrial dynamics and biogenesis in HepG2 cells

Silver nanoparticles (AgNPs) are inevitably released into the environment owing to their widespread applications in industry and medicine. The potential of their toxicity has aroused a great concern. Previous studies have shown that AgNPs exposure in HepG2 cells is primarily related to the damage of mitochondria, which includes induction of mitochondrial swelling and increase of intracellular levels of reactive oxygen species (ROS), the collapse of mitochondrial membrane potential and induction of apoptosis through a mitochondrial pathway. In this study, the effects of AgNPs exposure in HepG2 cells on mitochondrial dynamics and biogenesis were investigated. AgNPs were found to induce mitochondrial morphological and structural alterations. The expressions of key proteins (Drp1, Fis1, OPA1, Mff, Mfn1, and Mfn2) related to mitochondrial fission/fusion event were changed. Especially the expression of fission-related protein 1 (p-Drp1) (Ser616) was significantly up-regulated, whereas the expression of mitochondrial biogenesis protein (PGC-1α) was reduced in AgNP-treated cells. Concomitantly, the expression of autophagy marker proteins (LC3B and p62) was increased. The results suggested that AgNPs could trigger cytotoxicity by targeting the mitochondria, resulting in the disruption of mitochondrial function, damage to the mitochondrial structure and morphology, interfering in mitochondrial dynamics and biogenesis. The mitochondria could be a critical target of AgNPs in cells. The functions of mitochondria could be used for assessing the cytotoxic effects associated with AgNPs in cells.

Spatial targeting of Bcl-2 on endoplasmic reticulum and mitochondria in cancer cells by lipid nanoparticles

The presence of the same proteins at different sub-cellular locations with completely different functions adds to the complexity of signalling pathways in cancer.

Phloroglucinol-conjugated gold nanoparticles targeting mitochondrial membrane potential of human cervical (HeLa) cancer cell lines

In recent, targeting mitochondria in cancer is considered to be a challenging task. This report illustrates preliminary findings from an investigation of the conjugation of gold nanoparticles with a bioactive natural compound, phloroglucinol targeting mitochondrial transmembrane potential of HeLa cancer cells. We systematically investigated the formation of gold-nano conjugates over precisely controlled reaction conditions. Their sharp features enable superior surface plasmon resonance, morphology, surface charge, and stability. We show that gold-nano conjugates scavenging free radicals and persuade cell death in HeLa cancer cells. We also show that gold-nano conjugates induce apoptosis by promoting mitochondrial transmembrane permeation via fluorescent microscopic studies. This work gives new insights into bridging metabolomics and nanotechnology into developing novel lead therapeutic molecules.

Cell death and mitochondrial dysfunction induced by the dietary non-proteinogenic amino acid L-azetidine-2-carboxylic acid (Aze)

In addition to the 20 protein amino acids that are vital to human health, hundreds of naturally occurring amino acids, known as non-proteinogenic amino acids (NPAAs), exist and can enter the human food chain. Some NPAAs are toxic through their ability to mimic protein amino acids and this property is utilised by NPAA-containing plants to inhibit the growth of other plants or kill herbivores. The NPAA L-azetidine-2-carboxylic acid (Aze) enters the food chain through the use of sugar beet (Beta vulgaris) by-products as feed in the livestock industry and may also be found in sugar beet by-product fibre supplements. Aze mimics the protein amino acid L-proline and readily misincorporates into proteins. In light of this, we examined the toxicity of Aze to mammalian cells in vitro. We showed decreased viability in Aze-exposed cells with both apoptotic and necrotic cell death. This was accompanied by alterations in endosomal-lysosomal activity, changes to mitochondrial morphology and a significant decline in mitochondrial function. In summary, the results show that Aze exposure can lead to deleterious effects on human neuron-like cells and highlight the importance of monitoring human Aze consumption via the food chain.

Internalization and effects on cellular ultrastructure of nickel nanoparticles in rat kidneys

Purpose: Since nanoparticles (NPs) are beginning to be introduced in medicine and industry, it is mendatory to evaluate their biological side-effects, among other things. The present study aimed to investigate the pathways by which nickel nanoparticles (NiNPs) enter nephrons and to evaluate their localization and effects on cellular ultrastructure.

Methods: Rats were injected intraperitoneally with 20 nm NiNPs (20 mg/Kg/b.w./day) for 28 consecutive days. Transmission electron microscope technique was used to detect localization of NiNPs and their effects on cellular ultrastructure in rat kidneys. Additionally, measurements of certain biochemical parameters such as creatinine, urea, uric acid and phosphorus for investigating renal function following NiNPs treatment were taken.

Results: The presence of NiNPs in the nephrons in treated rats was confirmed by transmission electron microscopy. NiNPs entered the renal tubules cells via various pathways. The results indicated that NiNPs administration induced ultrastructural changes in the proximal cells of renal tubules and certain glomerular cells (podocytes and mesangial cells). Additionally, NiNPs were found to be localized in the mitochondria, which led to a significant decrease in their density and morphology. Furthermore, cell death was induced in the glomerular cells as found with a Terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) assay and through detection of p35 using immunohistochemical staining.

Conclusion: Herein, NiNPs were found to induce various cellular ultrastructural changes in the kidneys of rats. NiNPs used diverse pathways to internalize into the cytoplasm of the proximal convoluted tubules (PT) cells across the basement membrane, and also through the plasma membrane of two adjacent PT cells. NiNPs internalization, accumulation and their alterations of the cellular ultrastructure affected rat renal function.

Supramolecular self-assembly of triazine-based small molecules: targeting the endoplasmic reticulum in cancer cells

The endoplasmic reticulum (ER) is one of the most important organelles controlling myriads of cellular functions including protein folding/misfolding/unfolding, calcium ion homeostasis and lipid biosynthesis. Subsequently, due to its functional dysregulation in cancer cells, it has emerged as an interesting target for anti-cancer therapy. However, specific targeting of the ER in cancer cells remains a major challenge due to the lack of ER-selective chemical tools. Furthermore, for performing multiple cellular functions the ER is dependent on the nucleus through complicated cross-talk. Herein, we have engineered a supramolecular self-assembled hexameric rosette structure from two small molecules: tri-substituted triazine and 5-fluorouracil (5-FU). This rosette structure consists of an ER-targeting moiety with a fluorescence tag, an ER-stress inducer and a nuclear DNA damaging drug simultaneously, which further self-assembled into an ER-targeting spherical nano-scale particle (ER-NP). These ER-NPs internalized into HeLa cervical cancer cells by macropinocytosis and specifically localized into the ER to induce ER stress and DNA damage leading to cell death through apoptosis. Interestingly, ER-NPs initiated autophagy, inhibited by a combination of ER-NPs and chloroquine (CQ) to augment cancer cell death. This work has the potential to exploit the concept of supramolecular self-assembly into developing novel nano-scale materials for specific sub-cellular targeting of multiple organelles for future anti-cancer therapy.

Enhanced combination cancer therapy using lipid-calcium carbonate/phosphate nanoparticles as a targeted delivery platform

Aim: Melanoma, the most life-threatening skin cancer, requires more effective therapies. Methodology: A new folic acid (FA) receptor-targeted lipid-coated calcium carbonate/phosphate (LCCP) nanoparticle was synthesized, incorporating two often-used therapeutics, cell death siRNA and α-tocopheryl succinate. Results: The nanoparticles were spherical, with an average size of 40 nm. The nanoparticles exhibited a high gene/drug loading efficiency (60%), with folic acid-enhanced cellular uptake. The nanoparticles with both therapeutics enhanced inhibition of B16F0 melanoma cell growth, showing a moderate synergistic effect. The mechanism of the inhibition is associated with induction of cell apoptosis and cell cycle arrest at G1 phase. Conclusion: Our data indicate that lipid-coated calcium carbonate/phosphate nanoparticles are a potential platform for targeted therapy for melanoma.

Assessment of zero-valent iron-based nanotherapeutics for ferroptosis induction and resensitization strategy in cancer cells

Addressing nanomedicine resistance is critical for its ultimate clinical success; despite this, advancing the therapeutic designs for cancer therapy are rarely discussed in the literature.

Cascade Amplifiers of Intracellular Reactive Oxygen Species Based on Mitochondria-Targeted Core-Shell ZnO-TPP@D/H Nanorods for Breast Cancer Therapy

Tumor cells are vulnerable to reactive oxygen species (ROS). However, it is still a challenge to induce ROS efficiently in tumor cells. In this study, cascade amplifiers of intracellular ROS based on charge-reversible mitochondria-targeted ZnO-TPP@D/H nanorods (NRs) were first developed for breast cancer therapy. The core-shell ZnO-TPP@D/H NR with a particle size of 179.60 ± 5.67 nm was composed of a core of a ZnO NR, an inner shell of triphenyl phosphonium (TPP), and an outer shell of heparin. Doxorubicin (DOX) was loaded on ZnO-TPP@D/H NRs with high drug loading efficiency of 22.00 ± 0.18%. The zeta potential of ZnO-TPP@D/H NRs varied from 24.00 ± 0.83 to -34.06 ± 0.87 mV after heparin coating, protecting ZnO-TPP@D/H NRs from nonspecific adsorption in circulation. Mitochondrial targeting was achieved after the degradation of heparin. Cellular uptake assays showed that ZnO-TPP@D/H NRs could accumulate in mitochondria. ROS generation assays showed that ZnO-TPP@D/H NRs could triple the intracellular ROS in 4T1 cells (highly metastatic breast cancer cells) than free DOX. Western blot demonstrated that ZnO-TPP@D/H NRs dramatically induced cell apoptosis in 4T1 cells. In vivo experiments suggested the antitumor potential of ZnO-TPP@D/H NRs.

An α-tocopheryl succinate enzyme-based nanoassembly for cancer imaging and therapy

Nanoassembly (NA) based on a D-α-tocopherol succinate (αTS) conjugated lysozyme (Lys) (Lys-αTS) was fabricated for tumor-selective delivery of curcumin (CUR) for breast cancer therapy. Lys and αTS were used as a biocompatible enzyme and a hydrophobic residue, respectively, for the preparation of nanocarriers in this study. Compared with CUR-loaded cross-linked Lys (c-Lys/CUR) NA, Lys-αTS/CUR NA exhibited a smaller hydrodynamic size (213 nm mean diameter), a narrower size distribution, and a more spherical shape. Sustained drug release was observed from the Lys-αTS/CUR NA for five days at a normal physiological pH (pH 7.4). The developed Lys-αTS/CUR NA showed enhanced cellular accumulation, antiproliferative effects, and apoptotic efficacies in MDA-MB-231 human breast adenocarcinoma cells. According to the results of optical imaging test in the MDA-MB-231 tumor-bearing mouse models, the Lys-αTS/CUR NA-injected group exhibited a more tumor-selective accumulation pattern, rather than being distributed in the normal tissues and organs. The observed tumor targetability of Lys-αTS/CUR was further studied, which revealed improved in vivo anticancer activities (better inhibition of tumor growth and induction of apoptosis in the tumor tissue) after an intravenous administration in the MDA-MB-231 tumor-bearing mouse models. All these results indicate that the newly developed enzyme-based nanocarrier, the Lys-αTS NA, can be a promising candidate for the therapy of breast cancers.

Oxidative stress mediated cytotoxicity of tin (IV) oxide (SnO2) nanoparticles in human breast cancer (MCF-7) cells

Due to unique optical and electronic properties tin oxide nanoparticles (SnO₂ NPs) have shown potential for various applications including solar cell, catalyst, and biomedicine. However, there is limited information concerning the interaction of SnO₂ NPs with human cells. In this study, we explored the potential mechanisms of cytotoxicity of SnO₂ NPs in human breast cancer (MCF-7) cells. Results demonstrated that SnO₂ NPs induce cell viability reduction, lactate dehydrogenase leakage, rounded cell morphology, cell cycle arrest and low mitochondrial membrane potential in dose- and time-dependent manner. SnO₂ NPs were also found to provoke oxidative stress evident by generation of reactive oxygen species (ROS), hydrogen peroxide (H₂O₂) and lipid peroxidation, while depletion of glutathione (GSH) level and lower activity of several antioxidant enzymes. Remarkably, we observed that ROS generation, GSH depletion, and cytotoxicity induced by SnO₂ NPs were effectively abrogated by antioxidant N-acetylcycteine. Our data have shown that SnO₂ NPs induce toxicity in MCF-7 cells via oxidative stress. This study warrants further research to explore the genotoxicity of SnO₂ NPs in different types of cancer cells.

Precisely Striking Tumors without Adjacent Normal Tissue Damage via Mitochondria-Templated Accumulation

Ignored damage in adjacent normal tissue is fatal especially in some specific tumor therapy such as brain tumors, but it remains a great challenge to conquer due to random drug diffusion and tumor complexity. Herein, we show that hyperthermia in mitochondria, an interparticle plasmonic coupling effect activated nanoevent, selectively strikes tumor tissues without damaging adjacent normal tissues. Spherical gold nanoparticles with a mitochondria-targeting moiety, triphenyl phosphonium, preferentially accumulated inside tumor mitochondria and reached the threshold to activate interparticle plasmonic coupling effect among gold nanoparticles, realizing selective light-thermal conversion and mitochondrial dysfunction in tumor, whereas little hyperthermia and mitochondrial dysfunction were observed in adjacent normal tissues. In vivo study revealed that the temperature increment in tumor tissue with irradiation was nearly 4-fold that in adjacent normal tissue. This subcellular organelle-templated accumulation strategy provides a therapeutic model for highly selective tumor therapy with negligible local side effects.