Exploiting Mitochondrial Vulnerabilities to Trigger Apoptosis Selectively in Cancer Cells

Oxidative stress is two-sided in the treatment of acute myeloid leukemia

INTRODUCTION

Oxidative stress caused by elevated ROS, as a novel therapeutic mechanism, has been implicated in various tumors including AML. AML cells are chronically under oxidative stress, yet overreliance on ROS production makes tumor cells increasingly vulnerable to further damage. Reducing the cytotoxic effect of ROS on normal cells while killing leukemia stem cell (LSC) with high levels of reactive oxygen species is a new challenge for oxidative stress therapy in leukemia.

METHODS

By searching literature databases, we summarized recent relevant studies. The relationship of ROS on AML genes, signaling pathways, and transcription factors, and the correlation of ROS with AML bone marrow microenvironment and autophagy were summarized. In addition, we summarize the current status of research on ROS and AML therapeutics. Finally, we discuss the research progress on redox resistance in AML.

RESULTS

This review discusses the evidence showing the link between redox reactions and the progression of AML and compiles the latest research findings that will facilitate future biological studies of redox effects associated with AML treatment.

CONCLUSION

We believe that exploiting this unique oxidative stress property of AML cells may provide a new way to prevent relapse and drug resistance.

Targeting Mitochondria for Cancer Treatment

There is an increasing accumulation of data on the exceptional importance of mitochondria in the occurrence and treatment of cancer, and in all lines of evidence for such participation, there are both energetic and non-bioenergetic functional features of mitochondria. This analytical review examines three specific features of adaptive mitochondrial changes in several malignant tumors. The first feature is characteristic of solid tumors, whose cells are forced to rebuild their energetics due to the absence of oxygen, namely, to activate the fumarate reductase pathway instead of the traditional succinate oxidase pathway that exists in aerobic conditions. For such a restructuring, the presence of a low-potential quinone is necessary, which cannot ensure the conventional conversion of succinate into fumarate but rather enables the reverse reaction, that is, the conversion of fumarate into succinate. In this scenario, complex I becomes the only generator of energy in mitochondria. The second feature is the increased proliferation in aggressive tumors of the so-called mitochondrial (peripheral) benzodiazepine receptor, also called translocator protein (TSPO) residing in the outer mitochondrial membrane, the function of which in oncogenic transformation stays mysterious. The third feature of tumor cells is the enhanced retention of certain molecules, in particular mitochondrially directed cations similar to rhodamine 123, which allows for the selective accumulation of anticancer drugs in mitochondria. These three features of mitochondria can be targets for the development of an anti-cancer strategy.

A review for cancer treatment with mushroom metabolites through targeting mitochondrial signaling pathway: In vitro and in vivo evaluations, clinical studies and future prospects for mycomedicine

Resistance to apoptosis stands as a roadblock to the successful pharmacological execution of anticancer drug effect. A comprehensive insight into apoptotic signaling pathways and an understanding of the mechanisms of apoptosis resistance are crucial to unveil new drug targets. At this juncture, researchers are heading towards natural sources in particular, mushroom as their potential drugs leads to being the reliable source of potent bioactive compounds. Given the continuous increase in cancer cases, the potent anticancer efficacy of mushrooms has inevitably become a fascinating object to researchers due to their higher safety margin and multitarget. This review aimed to collect and summarize all the available scientific data on mushrooms from their extracts to bioactive molecules in order to suggest their anticancer attributes via a mitochondrion -mediated intrinsic signaling mechanism. Compiled data revealed that bioactive components of mushrooms including polysaccharides, sterols and terpenoids as well as extracts prepared using 15 different solvents from 53 species could be effective in the supportive treatment of 20 various cancers. The underlying therapeutic mechanisms of the studied mushrooms are explored in this review through diverse and complementary investigations: in vitro assays, pre-clinical studies and clinical randomized controlled trials. The processes mainly involved were ROS production, mitochondrial membrane dysfunction, and action of caspase 3, caspase 9, XIAP, cIAP, p53, Bax, and Bcl-2. In summary, the study provides facts pertaining to the potential beneficial effect of mushroom extracts and their active compounds against various types of cancer and is shedding light on the underlying targeted signaling pathways.

Role of Apoptosis in the Pathogenesis of Osteoarthritis: An Explicative Review

Apoptosis is a complex regulatory, active cell death process that plays a role in cell development, homeostasis, and ageing. Cancer, developmental defects, and degenerative diseases are all pathogenic disorders caused by apoptosis dysregulation. Osteoarthritis (OA) is by far the most frequently diagnosed joint disease in the aged, and it is characterized by the ongoing breakdown of articular cartilage, which causes severe disability. Multiple variables regulate the anabolic and catabolic pathways of the cartilage matrix, which either directly or indirectly contribute to cartilage degeneration in osteoarthritis. Articular cartilage is a highly specialized tissue made up of an extracellular matrix of cells that are tightly packed together. As a result, chondrocyte survival is crucial for the preservation of an optimal cartilage matrix, and chondrocyte characteristics and survival compromise may result in articular cartilage failure. Inflammatory cytokines can either promote or inhibit apoptosis, the process of programmed cell death. Pro-apoptotic cytokines like TNF-α can induce cell death, while anti-apoptotic cytokines like IL-4 and IL-10 protect against apoptosis. The balance between these cytokines plays a critical role in determining cell fate and has implications for tissue damage and disease progression. Similarly, they contribute to the progression of OA by disrupting the metabolic balance in joint tissues by promoting catabolic and anabolic pathways. Their impact on cell joints, as well as the impacts of cell signalling pathways on cytokines and inflammatory substances, determines their function in osteoarthritis development. Apoptosis is evident in osteoarthritic cartilage; however, determining the relative role of chondrocyte apoptosis in the aetiology of OA is difficult, and the rate of apoptotic chondrocytes in osteoarthritic cartilage is inconsistent. The current study summarises the role of apoptosis in the development of osteoarthritis, the mediators, and signalling pathways that trigger the cascade of events, and the other inflammatory features involved.

Functional effect of indole-3 carbinol in the viability and invasive properties of cultured cancer cells

Cancer treatment typically involves multiple strategies, such as surgery, radiotherapy, and chemotherapy, to remove tumors. However, chemotherapy often causes side effects, and there is a constant search for new drugs to alleviate them. Natural compounds are a promising alternative to this problem. Indole-3-carbinol (I3C) is a natural antioxidant agent that has been studied as a potential cancer treatment. I3C is an agonist of the aryl hydrocarbon receptor (AhR), a transcription factor that plays a role in the expression of genes related to development, immunity, circadian rhythm, and cancer. In this study, we investigated the effect of I3C on cell viability, migration, invasion properties, as well as mitochondrial integrity in hepatoma, breast, and cervical cancer cell lines. We found that all tested cell lines showed impaired carcinogenic properties and alterations in mitochondrial membrane potential after treatment with I3C. These results support the potential use of I3C as a supplementary treatment for various types of cancer.

Preclinical evaluation of Mito-LND, a targeting mitochondrial metabolism inhibitor, for glioblastoma treatment

BACKGROUND

Glioblastoma (GBM) is a brain tumor with the highest level of malignancy and the worst prognosis in the central nervous system. Mitochondrial metabolism plays a vital role in the occurrence and development of cancer, which provides critical substances to support tumor anabolism. Mito-LND is a novel small-molecule inhibitor that can selectively inhibit the energy metabolism of tumor cells. However, the therapeutic effect of Mito-LND on GBM remains unclear.

METHODS

The present study evaluated the inhibitory effect of Mito-LND on the growth of GBM cells and elucidated its potential mechanism.

RESULTS

The results showed that Mito-LND could inhibit the survival, proliferation and colony formation of GBM cells. Moreover, Mito-LND induced cell cycle arrest and apoptosis. Mechanistically, Mito-LND inhibited the activity of mitochondrial respiratory chain complex I and reduced mitochondrial membrane potential, thus promoting ROS generation. Importantly, Mito-LND could inhibit the malignant proliferation of GBM by blocking the Raf/MEK/ERK signaling pathway. In vivo experiments showed that Mito-LND inhibited the growth of GBM xenografts in mice and significantly prolonged the survival time of tumor-bearing mice.

CONCLUSION

Taken together, the current findings support that targeting mitochondrial metabolism may be as a potential and promising strategy for GBM therapy, which will lay the theoretical foundation for further clinical trials on Mito-LND in the future.

Cyclic anthraquinone derivatives, unique G-quadruplex binders, selectively induce cancer cell apoptosis and inhibit tumor growth

Cyclic anthraquinone derivatives (cAQs), which link two side chains of 1,5-disubstituted anthraquinone as a threading DNA intercalator, have been developed as G-quartet (G4) DNA-specific ligands. Among the cAQs, cAQ-mBen linked through the 1,3-position of benzene had the strongest affinity for G4 recognition and stabilization in vitro and was confirmed to bind to the G4 structure in vivo, selectively inhibiting cancer cell proliferation in correlation with telomerase expression levels and triggering cell apoptosis. RNA-sequencing analysis further indicated that differentially expressed genes regulated by cAQ-mBen were profiled with more potential quadruplex-forming sequences. In the treatment of the tumor-bearing mouse model, cAQ-mBen could effectively reduce tumor tissue and had less adverse effects on healthy tissue. These results suggest that cAQ-mBen can be a potential cancer therapeutic agent as a G4 binder.

Chemical exposure and alveolar macrophages responses: 'the role of pulmonary defense mechanism in inhalation injuries'

Epidemiological and clinical studies have indicated an association between particulate matter (PM) exposure and acute and chronic pulmonary inflammation, which may be registered as increased mortality and morbidity. Despite the increasing evidence, the pathophysiology mechanism of these PMs is still not fully characterised. Pulmonary alveolar macrophages (PAMs), as a predominant cell in the lung, play a critically important role in these pathological mechanisms. Toxin exposure triggers events associated with macrophage activation, including oxidative stress, acute damage, tissue disruption, remodelling and fibrosis. Targeting macrophage may potentially be employed to treat these types of lung inflammation without affecting the natural immune response to bacterial infections. Biological toxins, their sources of exposure, physical and other properties, and their effects on the individuals are summarised in this article. Inhaled particulates from air pollution and toxic gases containing chemicals can interact with alveolar epithelial cells and immune cells in the airways. PAMs can sense ambient pollutants and be stimulated, triggering cellular signalling pathways. These cells are highly adaptable and can change their function and phenotype in response to inhaled agents. PAMs also have the ability to polarise and undergo plasticity in response to tissue damage, while maintaining resistance to exposure to inhaled agents.

Oxidative stress induced by Pollonein-LAAO, a new L-amino acid oxidase from Bothrops moojeni venom, prompts prostate tumor spheroid cell death and impairs the cellular invasion process in vitro

Cancer cells produce abnormal levels of reactive oxygen species (ROS) that contribute to promote their malignant phenotype. In this framework, we hypothesized that the change in ROS concentration above threshold could impair key events of prostate cancer cells (PC-3) progression. Our results demonstrated that Pollonein-LAAO, a new L-amino acid oxidase obtained from Bothrops moojeni venom, was cytotoxic to PC-3 cells in two-dimensional and in tumor spheroid assays. Pollonein-LAAO was able to increase the intracellular ROS generation that culminates in cell death from apoptosis by both intrinsic and extrinsic pathways due to the up-regulation of TP53, BAX, BAD, TNFRSF10B and CASP8. Additionally, Pollonein-LAAO reduced mitochondrial membrane potential and caused G0/G1 phase to delay, due to the up-regulation of CDKN1A and the down-regulation of the expression of CDK2 and E2F. Interestingly, Pollonein-LAAO inhibited critical steps of the cellular invasion process (migration, invasion and adhesion), due to the down-regulation of SNAI1, VIM, MMP2, ITGA2, ITGAV and ITGB3. Furthermore, the Pollonein-LAAO effects were associated with the intracellular ROS production, since the presence of catalase restored the invasiveness of PC-3 cells. In this sense, this study contributes to the potential use of Pollonein-LAAO as ROS-based agent to enhance the current understanding of cancer treatment strategies.

GSK461364A suppresses proliferation of gastric cancer cells and induces apoptosis

Polo-like kinase-1 (PLK1) is crucial in regulating cell division and has been shown to have an oncogenic function in several cancers. Since PLK1 overexpression is closely related to tumorigenesis and has been correlated with poor clinical outcomes, specific inhibition of PLK1 in cancer cells is a promising approach for developing new anticancer drugs. In this context, the aim of the present study was to evaluated the potential cytotoxic effects of GSK461364A, a competitive inhibitor for PLK1, in gastric cancer cell line SNU-1 cells and explored its cytotoxic mechanism. The cells were exposed to GSK461364A at different concentrations ranging from 1 to 40 μM for 24 h, and it showed considerable cytotoxicity with an IC50 value of 4.34 μM. The treatment of SNU-1 cells with GSK461364A results in cell cycle arrest at the G2/M phase, decreased mitochondrial membrane potential, and increased apoptosis as indicated by Annexin V binding assay. In addition, GSK461364A treatment significantly increased the total oxidant (TOS) level, a signal of oxidative stress, and increased cleaved PARP and 8-oxo-dG levels as an indicator of DNA damage. ELISA experiments evaluating Bax, BCL-2, and cleaved caspase-3 also confirmed the apoptotic effect of GSK461364A. Current findings suggest that GSK461364A may be a chemotherapeutic agent in patients with gastric cancer. Nevertheless, more research is needed to evaluate GSK461364A as a cancer treatment drug.

CRIF1 siRNA-Encapsulated PLGA Nanoparticles Suppress Tumor Growth in MCF-7 Human Breast Cancer Cells

Mitochondrial oxidative phosphorylation (OXPHOS) system dysfunction in cancer cells has been exploited as a target for anti-cancer therapeutic intervention. The downregulation of CR6-interacting factor 1 (CRIF1), an essential mito-ribosomal factor, can impair mitochondrial function in various cell types. In this study, we investigated whether CRIF1 deficiency induced by siRNA and siRNA nanoparticles could suppress MCF-7 breast cancer growth and tumor development, respectively. Our results showed that CRIF1 silencing decreased the assembly of mitochondrial OXPHOS complexes I and II, which induced mitochondrial dysfunction, mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential depolarization, and excessive mitochondrial fission. CRIF1 inhibition reduced p53-induced glycolysis and apoptosis regulator (TIGAR) expression, as well as NADPH synthesis, leading to additional increases in ROS production. The downregulation of CRIF1 suppressed cell proliferation and inhibited cell migration through the induction of G0/G1 phase cell cycle arrest in MCF-7 breast cancer cells. Similarly, the intratumoral injection of CRIF1 siRNA-encapsulated PLGA nanoparticles inhibited tumor growth, downregulated the assembly of mitochondrial OXPHOS complexes I and II, and induced the expression of cell cycle protein markers (p53, p21, and p16) in MCF-7 xenograft mice. Thus, the inhibition of mitochondrial OXPHOS protein synthesis through CRIF1 deletion destroyed mitochondrial function, leading to elevated ROS levels and inducing antitumor effects in MCF-7 cells.

Mitophagy regulation in aging and neurodegenerative disease

Mitochondria are the primary cellular energy generators, supplying the majority of adenosine triphosphate through oxidative phosphorylation, which is necessary for neuron function and survival. Mitophagy is the metabolic process of eliminating dysfunctional or redundant mitochondria. It is a type of autophagy and it is crucial for maintaining mitochondrial and neuronal health. Impaired mitophagy leads to an accumulation of damaged mitochondria and proteins leading to the dysregulation of mitochondrial quality control processes. Recent research shows the vital role of mitophagy in neurons and the pathogenesis of major neurodegenerative diseases. Mitophagy also plays a major role in the process of aging. This review describes the alterations that are being caused in the mitophagy process at the molecular level in aging and in neurodegenerative diseases, particularly Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis, also looks at how mitophagy can be exploited as a therapeutic target for these diseases.

Knockdown of CALM2 increases the sensitivity to afatinib in HER2-amplified gastric cancer cells by regulating the Akt/FoxO3a/Puma axis

Gastric cancer (GC) is a global health issue that lacks effective treatment options. Afatinib is a tyrosine kinase inhibitor (TKI) that has shown promising results in the treatment of GC. However, resistance to afatinib is inevitable and hampers its clinical application. To date, there is limited knowledge regarding the mechanisms underlying the resistance of GC cells to afatinib. This study aimed to identify novel factors that may contribute to the resistance of GC cells to afatinib. We found that upregulation of calmodulin 2 (CALM2), a member of the CALM family, confers resistance to afatinib in GC cells. Knockdown of CALM2 can overcome the resistance to afatinib by promoting mitochondrial apoptosis in a caspase-dependent manner. Mechanistically, it was found that the downregulation of CALM2 led to the upregulation of the FoxO3a/Puma axis. Inhibition of either FoxO3a or Puma abrogated the effects of CALM2 downregulation in GC cells. In addition, we revealed that CALM2 knockdown inhibited Akt signaling, which is responsible for blocking the FoxO3a/Puma axis. Altogether, our results indicated that CALM2 could be considered a potential target to overcome the resistance of GC cells to afatinib.

Marine Sponge-Derived Alkaloid Induces Mitochondrial Dysfunction and Inhibits the PI3K/AKT/mTOR Signaling Pathway against Burkitt's Lymphoma

Burkitt's lymphoma (BL) has a particularly extremely poor prognosis and the fastest growth rate among human tumors, and the development of new drugs for the treatment of BL is urgently needed. In this study, the cytotoxic properties of 3,7-bis(3,5-dimethylphenyl)-aaptamine (AP-51), a new semisynthetic alkaloid derived from the marine natural product aapatamine, were investigated using BL cell lines. Our results showed that AP-51 inhibited the proliferation of Daudi and Raji cells with IC50 values of 3.48 and 2.07 μM, respectively. Flow cytometry and Western blot analyses showed that AP-51 initiated G0/G1 phase arrest by modulating the expression of cyclin-dependent kinases (CDKs). AP-51 also induced apoptosis, as demonstrated by nuclear fragmentation, downregulation of BCL-XL and Mcl-1, and upregulation of cleaved caspase-9, cleaved caspase-3, cleaved-PARP, and cytochrome c, the markers of apoptosis regulated via the mitochondrial pathway. When it comes to mitochondria, AP-51 treatment also significantly increased the levels of intracellular mitochondrial superoxide, decreased ATP content, and reduced the expression of ATP synthase, as well as the expression of the mitochondrial respiratory chain complexes. Finally, AP-51 treatment significantly inhibited the PI3K/AKT/mTOR signaling pathway, which was shown to be associated with the induction of apoptosis. Collectively, these findings indicated that AP-51 initiated cell cycle arrest, induced apoptosis, caused mitochondrial dysfunction, and decreased the phosphorylation of PI3K/AKT/mTOR signaling pathway-related proteins and the protein levels of C-MYC, suggesting that AP-51 has therapeutic potential as a possible treatment for Burkitt's lymphoma.

Chemical Composition, Antitumor Properties, and Mechanism of the Essential Oil from Plagiomnium acutum T. Kop

Plagiomnium acutum T. Kop. (P. acutum) has been used as a traditional Chinese medicine for thousands of years to treat cancer but lacks evidence. The objective of this work was to reveal the chemical composition of P. acutum essential oil (PEO) and explore its potential antitumor activity and molecular mechanism. PEO was prepared by the simultaneous distillation-extraction method and characterized by gas chromatography/mass spectroscopy. CCK8 assay, flow cytometry, western blot, and immunofluorescence techniques were used to analyze the effects and mechanism of PEO against cancer cells. A total of 74 constituents of PEO were identified, with diterpenes (26.5%), sesquiterpenes (23.89%), and alcohols (21.81%) being the major constituents. Two terpenoids, selina-6-en-4-ol and dolabella-3,7-dien-18-ol, were detected in PEO for the first time. PEO showed significant cell growth inhibitory activity on HepG2 and A549 cells by blocking the G1 phase and inducing apoptosis, which may be attributed to its upregulation of p21^Cip1 and p27^Kip1 proteins and interference with mitochondrial membrane potential effect. Dolabella-3,7-dien-18-ol accounts for 25.5% of PEO and is one of the main active components of PEO, with IC₅₀ values in HepG2 and A549 cells of (25.820 ± 0.216) µg/mL and (23.597 ± 1.207) μg/mL, respectively. These results confirmed the antitumor medicinal value of P. acutum and showed great application potential in the pharmaceutical industry.

Roles of Mitochondria in Oral Squamous Cell Carcinoma Therapy: Friend or Foe?

Oral squamous cell carcinoma (OSCC) therapy is unsatisfactory, and the prevalence of the disease is increasing. The role of mitochondria in OSCC therapy has recently attracted increasing attention, however, many mechanisms remain unclear. Therefore, we elaborate upon relative studies in this review to achieve a better therapeutic effect of OSCC treatment in the future. Interestingly, we found that mitochondria not only contribute to OSCC therapy but also promote resistance, and targeting the mitochondria of OSCC via nanoparticles is a promising way to treat OSCC.

Fascaplysin Induces Apoptosis and Ferroptosis, and Enhances Anti-PD-1 Immunotherapy in Non-Small Cell Lung Cancer (NSCLC) by Promoting PD-L1 Expression

Fascaplysin is a natural product isolated from sponges with a wide range of anticancer activities. However, the mechanism of fascaplysin against NSCLC has not been clearly studied. In this study, fascaplysin was found to inhibit migration by regulating the wnt/β-catenin signaling pathway and reversing the epithelial-mesenchymal transition phenotype. Further research showed that the anti-NSCLC effect of fascaplysin was mainly through the induction of ferroptosis and apoptosis. Fascaplysin-induced ferroptosis in lung cancer cells, evidenced by increased levels of ROS and Fe²⁺ and downregulation of ferroptosis-associated protein and endoplasmic reticulum stress, was involved in fascaplysin-induced ferroptosis. In addition, ROS was found to mediate fascaplysin-induced apoptosis. Fascaplysin significantly upregulated the expression of PD-L1 in lung cancer cells, and enhanced anti-PD-1 antitumor efficacy in a syngeneic mouse model. Therefore, these results suggest that fascaplysin exerts anticancer effects by inducing apoptosis and ferroptosis in vitro, and improving the sensitivity of anti-PD-1 immunotherapy in vivo. Fascaplysin is a promising compound for the treatment of NSCLC.

A double-edged sword: ROS related therapies in the treatment of psoriasis

In the onset and progression of psoriasis, redox imbalance is a vital factor. It's widely accepted that too much reactive oxygen species (ROS) always make psoriasis worse. Recent research, however, has shown that the accumulation of ROS is not entirely detrimental, as it helps reduce psoriasis lesions by inhibiting epidermal proliferation and keratinocyte death. As a result, ROS appears to have two opposing effects on the treatment of psoriasis. In this review, the current ROS-related therapies for psoriasis, including basic and clinical research, are presented. Additionally, the design and therapeutic benefits of various drug delivery systems and therapeutic approaches are examined, and a potential balance between anti-oxidative stress and ROS accumulation is also trying to be investigated.

FBP1-Altered Carbohydrate Metabolism Reduces Leukemic Viability through Activating P53 and Modulating the Mitochondrial Quality Control System In Vitro

Acute myeloid leukemia (AML)—the most frequent form of adult blood cancer—is characterized by heterogeneous mechanisms and disease progression. Developing an effective therapeutic strategy that targets metabolic homeostasis and energy production in immature leukemic cells (blasts) is essential for overcoming relapse and improving the prognosis of AML patients with different subtypes. With respect to metabolic regulation, fructose-1,6-bisphosphatase 1 (FBP1) is a gluconeogenic enzyme that is vital to carbohydrate metabolism, since gluconeogenesis is the central pathway for the production of important metabolites and energy necessary to maintain normal cellular activities. Beyond its catalytic activity, FBP1 inhibits aerobic glycolysis—known as the “Warburg effect”—in cancer cells. Importantly, while downregulation of FBP1 is associated with carcinogenesis in major human organs, restoration of FBP1 in cancer cells promotes apoptosis and prevents disease progression in solid tumors. Recently, our large-scale sequencing analyses revealed FBP1 as a novel inducible therapeutic target among 17,757 vitamin-D-responsive genes in MV4-11 or MOLM-14 blasts in vitro, both of which were derived from AML patients with FLT3 mutations. To investigate FBP1′s anti-leukemic function in this study, we generated a new AML cell line through lentiviral overexpression of an FBP1 transgene in vitro (named FBP1-MV4-11). Results showed that FBP1-MV4-11 blasts are more prone to apoptosis than MV4-11 blasts. Mechanistically, FBP1-MV4-11 blasts have significantly increased gene and protein expression of P53, as confirmed by the P53 promoter assay in vitro. However, enhanced cell death and reduced proliferation of FBP1-MV4-11 blasts could be reversed by supplementation with post-glycolytic metabolites in vitro. Additionally, FBP1-MV4-11 blasts were found to have impaired mitochondrial homeostasis through reduced cytochrome c oxidase subunit 2 (COX2 or MT-CO2) and upregulated PTEN-induced kinase (PINK1) expressions. In summary, this is the first in vitro evidence that FBP1-altered carbohydrate metabolism and FBP1-activated P53 can initiate leukemic death by activating mitochondrial reprogramming in AML blasts, supporting the clinical potential of FBP1-based therapies for AML-like cancers.

Metformin enhances the osteogenic activity of rat bone marrow mesenchymal stem cells by inhibiting oxidative stress induced by diabetes mellitus: an in vitro and in vivo study

PURPOSE

The purpose of this study was to determine whether metformin (MF) could alleviate the expresssion of reactive oxygen species (ROS) and improve the osteogenic ability of bone marrow mesenchymal stem cells derived from diabetic rats (drBMSCs) in vitro, and to evaluate the effect of MF on the ectopic osteogenesis of drBMSCs in a nude mouse model in vivo.

METHODS

BMSCs were extracted from normal and diabetic rats. In vitro, a cell viability assay (Cell Counting Kit-8), tests of alkaline phosphatase (ALP) activity, and western blot analysis were first used to determine the cell proliferation and osteogenic differentiation of drBMSCs that were subjected to treatment with different concentrations of MF (0, 50, 100, 200, 500 μM). The cells were then divided into 5 groups: (1) normal rat BMSCs (the BMSCs derived from normal rats group), (2) the drBMSCs group, (3) the drBMSCs + Mito-TEMPO (10 μM, ROS scavenger) group, (4) the drBMSCs + MF (200 μM) group, and (5) the drBMSCs + MF (200 μM) + H₂O₂ (50 μM, ROS activator) group. Intracellular ROS detection, a senescence-associated β-galactosidase assay, ALP staining, alizarin red staining, western blotting, and immunofluorescence assays were performed to determine the effects of MF on oxidative stress and osteogenic differentiation in drBMSCs. In vivo, the effect of MF on the ectopic osteogenesis of drBMSCs was evaluated in a nude mouse model.

RESULTS

MF effectively reduced ROS levels in drBMSCs. The cell proliferation, ALP activity, mineral deposition, and osteogenic-related protein expression of drBMSCs were demonstrably higher in the MF-treated group than in the non-MF-treated group. H₂O₂ inhibited the effects of MF. In addition, ectopic osteogenesis was significantly increased in drBMSCs treated with MF.

CONCLUSIONS

MF promoted the proliferation and osteogenic differentiation of drBMSCs by inhibiting the oxidative stress induced by diabetes and enhenced the ectopic bone formation of drBMSCs in nude mice.

Mitochondrial adaptation in cancer drug resistance: prevalence, mechanisms, and management

Drug resistance represents a major obstacle in cancer management, and the mechanisms underlying stress adaptation of cancer cells in response to therapy-induced hostile environment are largely unknown. As the central organelle for cellular energy supply, mitochondria can rapidly undergo dynamic changes and integrate cellular signaling pathways to provide bioenergetic and biosynthetic flexibility for cancer cells, which contributes to multiple aspects of tumor characteristics, including drug resistance. Therefore, targeting mitochondria for cancer therapy and overcoming drug resistance has attracted increasing attention for various types of cancer. Multiple mitochondrial adaptation processes, including mitochondrial dynamics, mitochondrial metabolism, and mitochondrial apoptotic regulatory machinery, have been demonstrated to be potential targets. However, recent increasing insights into mitochondria have revealed the complexity of mitochondrial structure and functions, the elusive functions of mitochondria in tumor biology, and the targeting inaccessibility of mitochondria, which have posed challenges for the clinical application of mitochondrial-based cancer therapeutic strategies. Therefore, discovery of both novel mitochondria-targeting agents and innovative mitochondria-targeting approaches is urgently required. Here, we review the most recent literature to summarize the molecular mechanisms underlying mitochondrial stress adaptation and their intricate connection with cancer drug resistance. In addition, an overview of the emerging strategies to target mitochondria for effectively overcoming chemoresistance is highlighted, with an emphasis on drug repositioning and mitochondrial drug delivery approaches, which may accelerate the application of mitochondria-targeting compounds for cancer therapy.

Leonurus japonicus Houttuyn induces reactive oxygen species-mediated apoptosis via regulation of miR-19a-3p/PTEN/PI3K/AKT in U937 and THP-1 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Leonurus japonicus Houttuyn is a medicinal ingredient in more than 300 prescriptions in traditional Korean medicine. It is especially important for women's health and blood-related diseases. Recent research revealed that Leonurus japonicus Houttuyn extracts have antioxidative, anticancer, analgesic, anti-inflammatory, and neuroprotective properties.

AIM OF THE STUDY

However, its underlying anti-cancerous mechanisms remain unclear. This study elucidated the anticancer mechanism of Leonurus japonicus Houttuyn in U937 and THP-1 cancer cells.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was used for detecting main compound of Leonurus japonicus Houttuyn, rutin. EZ-Cytox cell viability assay, Western blot analysis, live and dead cell assay, 2', 7' dichlorofluorescin diacetate (DCFDA) assay, quantitative real-time PCR (qRT-PCR) analysis, and microRNA (miR) mimic transfection assay were applied to further investigate anti-cancer efficacies and underlying mechanism in U937 and THP-1 cells.

RESULTS

The main compound of Leonurus japonicus Houttuyn, rutin was detected using HPLC. The cytotoxic effect of Leonurus japonicus Houttuyn was exerted in U937 and THP-1 cancer cells but not in MDBK and IEC-6 normal cells. Leonurus japonicus Houttuyn decreased mitochondria membrane potential (ΔΨm). Consistently, Leonurus japonicus Houttuyn reduced the expression of survivin and cleaved caspase-9, caspase-3, and poly (ADP-ribose) polymerase (PARP). Cell death was increased in Leonurus japonicus Houttuyn treated groups. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and CCAAT-enhancer-binding protein homologous protein (CHOP) was increased and phosphatidylinositol-3-kinase (PI3K) and Protein kinase B (AKT) were decreased by Leonurus japonicus Houttuyn. Reactive oxygen speices generation was elevated by Leonurus japonicus Houttuyn and its cytotoxicity was reversed by N-acetyl-l-cysteine (NAC) pretreatment. Moreover, onco-microRNA (miR), miR-19a-3p was suppressed by Leonurus japonicus Houttuyn and transfection of miR-19a-3p mimic reversed the regulated PTEN, p-AKT, CHOP expression, attenuating Leonurus japonicus Houttuyn induced apoptosis.

CONCLUSIONS

These findings indicated that Leonurus japonicus Houttuyn has anti-cancer effects by regulation of PTEN/PI3K/AKT signal pathway and ROS-related ER stress-induced apoptosis via regulation of miR-19a-3p. Leonurus japonicus Houttuyn may be an effective candidate for triggering PTEN-dependent apoptosis of cancer cells related to acute myeloid leukemia.

Cisplatin Chemotherapy and Cochlear Damage: Otoprotective and Chemosensitization Properties of Polyphenols

Significance: Cisplatin is an important component of treatment regimens for different cancers. Notwithstanding that therapeutic success often results from partial efficacy or stabilizing the disease, chemotherapy failure is driven by resistance to drug treatment and occurrence of side effects, such as progressive irreversible ototoxicity. Cisplatin's side effects, including ototoxicity, are often dose limiting. Recent Advances: Cisplatin ototoxicity results from several mechanisms, including redox imbalance caused by reactive oxygen species production and lipid peroxidation, activation of inflammation, and p53 and its downstream pathways that culminate in apoptosis. Considerable efforts in research have targeted development of molecular interventions that can be concurrently administered with cisplatin or other chemotherapies to reduce side effect toxicities while preserving or enhancing the antineoplastic effects. Evidence from studies has indicated some polyphenols, such as curcumin, can help to regulate redox signaling and inflammatory effects. Furthermore, polyphenols can exert opposing effects in different types of tissues, that is, normal cells undergoing stressful conditions versus cancer cells. Critical Issues: This review article summarizes evidence of curcumin antioxidant effect against cisplatin-induced ototoxicity that is converted to a pro-oxidant activity in cisplatin-treated cancer cells, thus providing an ideal chemosensitivity combined with otoprotection. Polyphenols can modulate the adaptive responses to stress in the cisplatin-exposed cochlea. These adaptive effects can result from the interaction/cross talk between the cell's defenses, inflammatory molecules, and the key signaling molecules of signal transducers and activators of transcription 3 (STAT-3), nuclear factor κ-B (NF-κB), p53, and nuclear factor erythroid 2-related factor 2 (Nrf-2). Future Directions: We provide molecular evidence for alternative strategies for chemotherapy with cisplatin addressing the otoprotection and chemosensitization properties of polyphenols. Antioxid. Redox Signal. 36, 1229-1245.

In Vitro Effects of Mitochondria-Targeted Antioxidants in a Small-Cell Carcinoma of the Ovary of Hypercalcemic Type and in Type 1 and Type 2 Endometrial Cancer

Small-cell carcinoma of the ovary of hypercalcemic type (SCCOHT) and endometrial cancer from type 1 and type 2 are gynecological tumors that affect women worldwide. The treatment encompasses the use of cytotoxic drugs that are nonspecific and inefficient. “Mitocans”, a family of drugs that specifically target tumor cells’ mitochondria, might be a solution, as they conjugate compounds, such as antioxidants, with carriers, such as lipophilic cations, that direct them to the mitochondria. In this study, caffeic acid was conjugated with triphenylphosphonium (TPP), 4-picolinium, or isoquinolinium, forming 3 new compounds (Mito6_TPP, Mito6_picol., and Mito6_isoq.) that were tested on ovarian (COV434) and endometrial (Hec50co and Ishikawa) cancer cells. The results of MTT and neutral red assays suggested a time- and concentration-dependent decrease in cell viability in all tumor cell lines. The presence of apoptosis was indicated by the Giemsa and Höechst staining and by the decrease in mitochondrial membrane potential. The measurement of intracellular reactive oxygen species demonstrated the antioxidant properties of these compounds, which might be related to cell death. Generally, Mito6_TPP was more active at lower concentrations than Mito6_picol. or Mito6_isoq., but was accompanied by more cytotoxic effects, as shown by the lactate dehydrogenase release. Non-tumorous cells (HFF-1) showed no changes after treatment. This study assessed the potential of these compounds as anticancer agents, although further investigation is needed.

Rhodamine 101 Conjugates of Triterpenoic Amides Are of Comparable Cytotoxicity as Their Rhodamine B Analogs

Pentacyclic triterpenoic acids (betulinic, oleanolic, ursolic, and platanic acid) were selected and subjected to acetylation followed by the formation of amides derived from either piperazine or homopiperazine. These amides were coupled with either rhodamine B or rhodamine 101. All of these compounds were screened for their cytotoxic activity in SRB assays. As a result, the cytotoxicity of the parent acids was low but increased slightly upon their acetylation while a significant increase in cytotoxicity was observed for piperazinyl and homopiperazinyl amides. A tremendous improvement in cytotoxicity was observed; however, for the rhodamine B and rhodamine 101 conjugates, and compound 27, an ursolic acid derived homopiperazinyl amide holding a rhodamine 101 residue showed an EC50 = 0.05 µM for A2780 ovarian cancer cells while being less cytotoxic for non-malignant fibroblasts. To date, the rhodamine 101 derivatives presented here are the first examples of triterpene derivatives holding a rhodamine residue different from rhodamine B.

Targeting Glioblastoma via Selective Alteration of Mitochondrial Redox State

Simple Summary

Glioblastoma is characterized by a pronounced redox imbalance due to elevated glycolytic and mitochondrial oxidative metabolism. New therapeutic strategies have been developed to modulate glioblastoma redox signaling to effectively suppress growth and prolong survival. However, drug selectivity and therapeutic relapse prove to be the major challenges. We describe a pharmacological strategy for the selective targeting and treatment of glioblastoma using the redox active combination drug menadione/ascorbate, which is characterized by tolerance to normal cells and tissues. Menadione/ascorbate treatment of glioblastoma mice suppressed tumor growth and significantly increased survival without adverse side effects. This is accompanied by increased oxidative stress, decreased reducing capacity and decreased cellular density in the tumor alone, as well as increased brain perfusion and decreased regulation of several oncoproteins and oncometabolites, which implies modulation of the immune response and reduced drug resistance. We believe that this therapeutic strategy is feasible and promising and deserves the attention of clinicians.

Abstract

Glioblastoma is one of the most aggressive brain tumors, characterized by a pronounced redox imbalance, expressed in a high oxidative capacity of cancer cells due to their elevated glycolytic and mitochondrial oxidative metabolism. The assessment and modulation of the redox state of glioblastoma are crucial factors that can provide highly specific targeting and treatment. Our study describes a pharmacological strategy for targeting glioblastoma using a redox-active combination drug. The experiments were conducted in vivo on glioblastoma mice (intracranial model) and in vitro on cell lines (cancer and normal) treated with the redox cycling pair menadione/ascorbate (M/A). The following parameters were analyzed in vivo using MRI or ex vivo on tissue and blood specimens: tumor growth, survival, cerebral perfusion, cellular density, tissue redox state, expression of tumor-associated NADH oxidase (tNOX) and transforming growth factor-beta 1 (TGF-β1). Dose-dependent effects of M/A on cell viability, mitochondrial functionality, and redox homeostasis were evaluated in vitro. M/A treatment suppressed tumor growth and significantly increased survival without adverse side effects. This was accompanied by increased oxidative stress, decreased reducing capacity, and decreased cellular density in the tumor only, as well as increased cerebral perfusion and down-regulation of tNOX and TGF-β1. M/A induced selective cytotoxicity and overproduction of mitochondrial superoxide in isolated glioblastoma cells, but not in normal microglial cells. This was accompanied by a significant decrease in the over-reduced state of cancer cells and impairment of their “pro-oncogenic” functionality, assessed by dose-dependent decreases in: NADH, NAD⁺, succinate, glutathione, cellular reducing capacity, mitochondrial potential, steady-state ATP, and tNOX expression. The safety of M/A on normal cells was compromised by treatment with cerivastatin, a non-specific prenyltransferase inhibitor. In conclusion, M/A differentiates glioblastoma cells and tissues from normal cells and tissues by redox targeting, causing severe oxidative stress only in the tumor. The mechanism is complex and most likely involves prenylation of menadione in normal cells, but not in cancer cells, modulation of the immune response, a decrease in drug resistance, and a potential role in sensitizing glioblastoma to conventional chemotherapy.

Distinct mechanism of action for antitumoral neutral cyclometalated Pt(II)-complexes bearing antifungal imidazolyl-based drugs

Three neutral Pt(II) complexes containing 1-Methylimidazole and the antifungal imidazolyl drugs Clotrimazole and Bifonazole have been prepared. The general formula of the new derivatives is [Pt(κ²-(C^N)Cl(L)], where C^N stands for ppy = 2-phenylpyridinate, and L = 1-Methylimidazole (MeIm) for [Pt-MeIm]; L = Clotrimazole (CTZ) for [Pt-CTZ] and L = Bifonazole (BFZ) for [Pt-BFZ]). The complexes have been completely characterized in solution and the crystal structures of [Pt-BFZ] and [Pt-CTZ] have been resolved. Complexes [Pt-MeIm] and [Pt-BFZ] present higher cytotoxicity than cisplatin in SW480 (colon adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian cancer) cell lines. [Pt-MeIm] shows the highest accumulation in A549 cells, in agreement with its inability to interact with serum albumin. By contrast, [Pt-CTZ] and [Pt-BFZ] interact with serum proteins, a fact that reduces their bioavailability. The strongest interaction with bovine serum albumin (BSA) is found for [Pt-BFZ], which is the least internalized inside the cells. All the complexes are able to covalently interact with DNA. The most cytotoxic complexes, [Pt-MeIm] and [Pt-BFZ] induce cellular accumulation in G0/G1 and apoptosis by a similar pathway, probably involving a reactive oxygen species (ROS) generation mechanism. [Pt-BFZ] turns out to be the most efficient complex regarding ROS generation and causes mitochondrial membrane depolarization, whereas [Pt-MeIm] induces the opposite effect, hyperpolarization of the mitochondrial membrane. On the contrary, the least cytotoxic complex, [Pt-CTZ] cannot block the cell cycle or generate ROS and the mechanism by which it induces apoptosis could be a different one.

Screening the biological properties of transition metal carbamates reveals gold(I) and silver(I) complexes as potent cytotoxic and antimicrobial agents

We report a screening study aimed to assess for the first time the air- and water-stability and the biological potential of simple metal-carbamates. These molecular metallic species are based on elements belonging to the groups 4-5, 7-9 and 11, and tin, and are easily available from inexpensive reagents. Complexes [Ag(O₂CNEt₂)] (13-Ag) and [Au(O₂CNMe₂)(PPh₃)] (14-Au) resulted substantially stable in aqueous media and exhibited a potent in vitro cytotoxicity. Especially 13-Ag revealed a significant selectivity against the A549 lung adenocarcinoma and the A2780 ovarian cancer cell lines with respect to the noncancerous HEK293 cell line. Generation of ROS (reactive oxygen species) and mitochondrial membrane depolarization were recognized for 13-Ag and 14-Au; notwithstanding, the cell death mechanism is different in the two cases: apoptosis and cell cycle arrest in G0/G1 phase for 13-Ag; necroptosis and cell cycle arrest in S phase for 14-Au. Both 13-Ag and 14-Au are endowed with antibacterial activity, which is relatively stronger for 13-Ag towards Gram negative and for 14-Au towards Gram positive strains, respectively.

Brain Delivery of Curcumin Through Low-Intensity Ultrasound-Induced Blood-Brain Barrier Opening via Lipid-PLGA Nanobubbles

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Owing to the presence of blood-brain barrier (BBB), conventional pharmaceutical agents are difficult to the diseased nuclei and exert their action to inhibit or delay the progress of PD. Recent literatures have demonstrated that curcumin shows the great potential to treat PD. However, its applications are still difficult in vivo due to its poor druggability and low bioavailability through the BBB.

Methods

Melt-crystallization methods were used to improve the solubility of curcumin, and curcumin-loaded lipid-PLGA nanobubbles (Cur-NBs) were fabricated through encapsulating the curcumin into the cavity of lipid-PLGA nanobubbles. The bubble size, zeta potentials, ultrasound imaging capability and drug encapsulation efficiency of the Cur-NBs were characterized by a series of analytical methods. Low-intensity focused ultrasound (LIFU) combined with Cur-NB was used to open the BBB to facilitate curcumin delivery into the deep brain of PD mice, followed by behavioral evaluation for the treatment efficacy.

Results

The solubility of curcumin was improved by melt-crystallization methods, with 2627-fold higher than pure curcumin. The resulting Cur-NBs have a nanoscale size about 400 nm and show excellent contrast imaging performance. Curcumin drugs encapsulated into Cur-NBs could be effectively released when Cur-NBs were irradiated by LIFU at the optimized acoustic pressure, achieving 30% cumulative release rate within 6 h. Importantly, Cur-NBs combined with LIFU can open the BBB and locally deliver the curcumin into the deep-seated brain nuclei, significantly enhancing efficacy of curcumin in the Parkinson C57BL/6J mice model in comparison with only Cur-NBs and LIFU groups.

Conclusion

In this work, we greatly improved the solubility of curcumin and developed Cur-NBs for brain delivery of curcumin against PD through combining with LIFU-mediating BBB. Cur-NBs provide a platform for these potential drugs which are difficult to cross the BBB to treat PD disease or other central nervous system (CNS) diseases.

Hierarchical nanoclusters with programmed disassembly for mitochondria-targeted tumor therapy with MR imaging

Mitochondria are crucial metabolic organelles involved in tumorigenesis and tumor progression, and the induction of abnormal mitochondria metabolism is recognized as a strategy with strong potential for the exploration of advanced tumor therapeutics. Herein, hierarchical manganese silicate nanoclusters modified with triphenylphosphonium (MSNAs-TPP) were designed and synthesized for mitochondria-targeted tumor theranostics. The as-prepared MSNAs-TPP retains considerable dimensional and structural stability in the neutral physiological environment, favoring its accumulation at the tumor site. More interestingly, MSNAs-TPP may disassemble in a responsive manner to an acidic tumor microenvironment into ultrasmall manganese silicate nanocapsules (∼6 nm), enabling deep tumor penetration and mitochondria targeting. When reaching the mitochondria, the nanocapsules effectively deplete mitochondrial glutathione (GSH), and simultaneously release catalytic Mn²⁺ ions to induce amplified oxidative stress in the structure with the enriched CO₂ and H₂O₂ from mitochondria metabolism. As a result, MSNAs-TPP presents considerable antitumor effect without a clear side effect, both in vitro and in vivo. The study may provide an alternative concept in the development of intelligent nanotherapeutics for tumor treatment with high efficacy.

Effects of dietary inclusion of Radix Bupleuri extract on the growth performance, and ultrastructural changes and apoptosis of lung epithelial cells in broilers exposed to atmospheric ammonia

To explore whether Radix Bupleuri extract (RBE) could protect lung injury of broilers under ammonia (NH3) exposure, 360 one-d-old male broilers were randomly allocated to four groups of six replicates each in a 2 × 2 factorial design with two diets (the basal diet [control; CON] and the basal diet supplemented with RBE [RB]) and two air conditions (normal condition [<2 ppm of NH3; NOR] and NH3 exposure [70 ppm of NH3; NH70]). The RB diet contained 80 mg saikosaponins/kg diet. On day 7, the lung tissues were collected and the lung epithelial cells (LEC) were isolated. Our experimental results showed that the NH3 exposure decreased body weight gain and feed intake irrespective of dietary treatments during days 1 to 7. However, the RBE addition decreased feed consumption to body weight gain ratio in broilers under NH70 conditions. In the LEC of CON-fed broilers under NH70 conditions, Golgi stacks showed the dilation of cisternaes and reduced secretory vesicles, mitochondria enlarged, the inner membrane of mitochondria became obscure, and the cristae of mitochondria ruptured, whereas only a mild enlargement of Golgi cisternaes and the part rupture of mitochondrial cristaes occurred in the LEC of RB-fed broilers under NH70 conditions. The NH3 exposure increased malondialdehyde (MDA) level, but decreased total antioxidant capacity (T-AOC) in the lungs of CON-fed broilers. However, the RBE addition decreased MDA level and increased T-AOC in the lungs of broilers under NH70 conditions. Simultaneously, the NH3 exposure increased apoptotic rate (AR), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) level in the isolated LEC of CON-fed broilers. The RBE addition decreased AR, MMP, and ROS in the isolated LEC of broilers under NH70 condition. Besides, the NH3 exposure increased mRNA expression of B-cell lymphoma-2 associated X protein (BAX), caspase-3, and tumor necrosis factor α (TNF-α), but increased interferon γ (IFN-γ) mRNA abundance in the lungs of CON-fed broilers. The RBE supplement decreased mRNA levels of BAX, caspase-3, and TNF-α, but increased IFN-γ, interleukin (IL)-4, and IL-17 mRNA levels in the lungs of broilers under NH70 conditions. These results indicated that dietary RBE addition alleviated NH3 exposure-induced intercellular ultrastructural damage via mitochondrial apoptotic pathway, possibly due to RBE-induced increase of antioxidant capacity and immunomodulatory function in the lungs of broilers under NH3 exposure.

Lipid Catabolism and ROS in Cancer: A Bidirectional Liaison

Although cancer cell metabolism was mainly considered to rely on glycolysis, with the concomitant impairment of mitochondrial metabolism, it has recently been demonstrated that several tumor types are sustained by oxidative phosphorylation (OXPHOS). In this context, endogenous fatty acids (FAs) deriving from lipolysis or lipophagy are oxidised into the mitochondrion, and are used as a source of energy through OXPHOS. Because the electron transport chain is the main source of ROS, cancer cells relying on fatty acid oxidation (FAO) need to be equipped with antioxidant systems that maintain the ROS levels under the death threshold. In those conditions, ROS can act as second messengers, favouring proliferation and survival. Herein, we highlight the different responses that tumor cells adopt when lipid catabolism is augmented, taking into account the different ROS fates. Many papers have demonstrated that the pro- or anti-tumoral roles of endogenous FA usage are hugely dependent on the tumor type, and on the capacity of cancer cells to maintain redox homeostasis. In light of this, clinical studies have taken advantage of the boosting of lipid catabolism to increase the efficacy of tumor therapy, whereas, in other contexts, antioxidant compounds are useful to reduce the pro-survival effects of ROS deriving from FAO.

Nitro-Deficient Niclosamide Confers Reduced Genotoxicity and Retains Mitochondrial Uncoupling Activity for Cancer Therapy

Niclosamide is an oral anthelmintic drug, approved for use against tapeworm infections. Recent studies suggest however that niclosamide may have broader clinical applications in cancers, spurring increased interest in the functions and mechanisms of niclosamide. Previously, we reported that niclosamide targets a metabolic vulnerability in p53-deficient tumours, providing a basis for patient stratification and personalised treatment strategies. In the present study, we functionally characterised the contribution of the aniline 4'-NO2 group on niclosamide to its cellular activities. We demonstrated that niclosamide induces genome-wide DNA damage that is mechanistically uncoupled from its antitumour effects mediated through mitochondrial uncoupling. Elimination of the nitro group in ND-Nic analogue significantly reduced γH2AX signals and DNA breaks while preserving its antitumour mechanism mediated through a calcium signalling pathway and arachidonic acid metabolism. Lipidomics profiling further revealed that ND-Nic-treated cells retained a metabolite profile characteristic of niclosamide-treated cells. Notably, quantitative scoring of drug sensitivity suggests that elimination of its nitro group enhanced the target selectivity of niclosamide against p53 deficiency. Importantly, the results also raise concern that niclosamide may impose a pleiotropic genotoxic effect, which limits its clinical efficacy and warrants further investigation into alternative drug analogues that may ameliorate any potential unwanted side effects.

Antioxidants Threaten Multikinase Inhibitor Efficacy against Liver Cancer by Blocking Mitochondrial Reactive Oxygen Species

Sorafenib and regorafenib, multikinase inhibitors (MKIs) used as standard chemotherapeutic agents for hepatocellular carcinoma (HCC), generate reactive oxygen species (ROS) during cancer treatment. Antioxidant supplements are becoming popular additions to our diet, particularly glutathione derivatives and mitochondrial-directed compounds. To address their possible interference during HCC chemotherapy, we analyzed the effect of common antioxidants using hepatoma cell lines and tumor spheroids. In liver cancer cell lines, sorafenib and regorafenib induced mitochondrial ROS production and potent cell death after glutathione depletion. In contrast, cabozantinib only exhibited oxidative cell death in specific HCC cell lines. After sorafenib and regorafenib administration, antioxidants such as glutathione methyl ester and the superoxide scavenger MnTBAP decreased cell death and ROS production, precluding the MKI activity against hepatoma cells. Interestingly, sorafenib-induced mitochondrial damage caused PINK/Parkin-dependent mitophagy stimulation, altered by increased ROS production. Finally, in sorafenib-treated tumor spheroids, while ROS induction reduced tumor growth, antioxidant treatments favored tumor development. In conclusion, the anti-tumor activity of specific MKIs, such as regorafenib and sorafenib, is altered by the cellular redox status, suggesting that uncontrolled antioxidant intake during HCC treatment should be avoided or only endorsed to diminish chemotherapy-induced side effects, always under medical scrutiny.

Tunneling nanotubes, TNT, communicate glioblastoma with surrounding non-tumor astrocytes to adapt them to hypoxic and metabolic tumor conditions

Cell-to-cell communication is essential for the development and proper function of multicellular systems. We and others demonstrated that tunneling nanotubes (TNT) proliferate in several pathological conditions such as HIV, cancer, and neurodegenerative diseases. However, the nature, function, and contribution of TNT to cancer pathogenesis are poorly understood. Our analyses demonstrate that TNT structures are induced between glioblastoma (GBM) cells and surrounding non-tumor astrocytes to transfer tumor-derived mitochondria. The mitochondrial transfer mediated by TNT resulted in the adaptation of non-tumor astrocytes to tumor-like metabolism and hypoxia conditions. In conclusion, TNT are an efficient cell-to-cell communication system used by cancer cells to adapt the microenvironment to the invasive nature of the tumor.

Discovery of KV 1.3 ion channel inhibitors: Medicinal chemistry approaches and challenges

The KV 1.3 voltage-gated potassium ion channel is involved in many physiological processes both at the plasma membrane and in the mitochondria, chiefly in the immune and nervous systems. Therapeutic targeting KV 1.3 with specific peptides and small molecule inhibitors shows great potential for treating cancers and autoimmune diseases, such as multiple sclerosis, type I diabetes mellitus, psoriasis, contact dermatitis, rheumatoid arthritis, and myasthenia gravis. However, no KV 1.3-targeted compounds have been approved for therapeutic use to date. This review focuses on the presentation of approaches for discovering new KV 1.3 peptide and small-molecule inhibitors, and strategies to improve the selectivity of active compounds toward KV 1.3. Selectivity of dalatazide (ShK-186), a synthetic derivate of the sea anemone toxin ShK, was achieved by chemical modification and has successfully reached clinical trials as a potential therapeutic for treating autoimmune diseases. Other peptides and small-molecule inhibitors are critically evaluated for their lead-like characteristics and potential for progression into clinical development. Some small-molecule inhibitors with well-defined structure-activity relationships have been optimized for selective delivery to mitochondria, and these offer therapeutic potential for the treatment of cancers. This overview of KV 1.3 inhibitors and methodologies is designed to provide a good starting point for drug discovery to identify novel effective KV 1.3 modulators against this target in the future.

An understanding of mitochondria and its role in targeting nanocarriers for diagnosis and treatment of cancer

Nanotechnology has changed the entire paradigm of drug targeting and has shown tremendous potential in the area of cancer therapy due to its specificity. In cancer, several targets have been explored which could be utilized for the better treatment of disease. Mitochondria, the so-called powerhouse of cell, portrays significant role in the survival and death of cells, and has emerged as potential target for cancer therapy. Direct targeting and nanotechnology based approaches can be tailor-made to target mitochondria and thus improve the survival rate of patients suffering from cancer. With this backdrop, in present review, we have reemphasized the role of mitochondria in cancer progression and inhibition, highlighting the different targets that can be explored for targeting of disease. Moreover, we have also summarized different nanoparticulate systems that have been used for treatment of cancer via mitochondrial targeting.

Cancer Stem-Like Phenotype of Mitochondria Dysfunctional Hep3B Hepatocellular Carcinoma Cell Line

Mitochondria are major organelles that play various roles in cells, and mitochondrial dysfunction is the main cause of numerous diseases. Mitochondrial dysfunction also occurs in many cancer cells, and these changes are known to affect malignancy. The mitochondria of normal embryonic stem cells (ESCs) exist in an undifferentiated state and do not function properly. We hypothesized that mitochondrial dysfunction in cancer cells caused by the depletion of mitochondrial DNA might be similar to the mitochondrial state of ESCs. We generated mitochondria dysfunctional (ρ0) cells from the Hep3B hepatocellular carcinoma cell line and tested whether these ρ0 cells show cancer stem-like properties, such as self-renewal, chemotherapy resistance, and angiogenesis. Compared with Hep3B cells, the characteristics of each cancer stem-like cell were increased in Hep3B/ρ0 cells. The Hep3B/ρ0 cells formed a continuous and large sphere from a single cell. Additionally, the Hep3B/ρ0 cells showed resistance to the anticancer drug doxorubicin because of the increased expression of ATP-binding cassette Subfamily B Member 1. The Hep3B/ρ0 conditioned medium induced more and thicker blood vessels and increased the mobility and invasiveness of the blood vessel cells. Therefore, our data suggest that mitochondrial dysfunction can transform cancer cells into cancer stem-like cells.

Targeting mitochondrial ion channels for cancer therapy

Pharmacological targeting of mitochondrial ion channels is emerging as a promising approach to eliminate cancer cells; as most of these channels are differentially expressed and/or regulated in cancer cells in comparison to healthy ones, this strategy may selectively eliminate the former. Perturbation of ion fluxes across the outer and inner membranes is linked to alterations of redox state, membrane potential and bioenergetic efficiency. This leads to indirect modulation of oxidative phosphorylation, which is/may be fundamental for both cancer and cancer stem cell survival. Furthermore, given the crucial contribution of mitochondria to intrinsic apoptosis, modulation of their ion channels leading to cytochrome c release may be of great advantage in case of resistance to drugs triggering apoptotic events upstream of the mitochondrial phase. In the present review, we give an overview of the known mitochondrial ion channels and of their modulators capable of killing cancer cells. In addition, we discuss state-of-the-art strategies using mitochondriotropic drugs or peptide-based approaches allowing a more efficient and selective targeting of mitochondrial ion channel-linked events.

Study of the antilymphoma activity of pracinostat reveals different sensitivities of DLBCL cells to HDAC inhibitors

Histone deacetylase inhibitors (HDACis) are antitumor agents with distinct efficacy in hematologic tumors. Pracinostat is a pan-HDACi with promising early clinical activity. However, similar to other HDACis, its activity as a single agent is limited. Diffuse large B-cell lymphoma (DLBCL) includes distinct molecular subsets or metabolically defined subtypes that rely in different ways on the B-cell receptor signaling pathway, oxidative phosphorylation, and glycolysis for their survival. The antitumor activity of pracinostat has not been determined in lymphomas. We performed preclinical in vitro activity screening of 60 lymphoma cell lines that included 25 DLBCLs. DLBCL cells belonging to distinct metabolic subtypes were treated with HDACis for 6 hours or 14 days followed by transcriptional profiling. DLBCL xenograft models enabled assessment of the in vivo antilymphoma activity of pracinostat. Combination treatments with pracinostat plus 10 other antilymphoma agents were performed. Western blot was used to assess acetylation levels of histone and nonhistone proteins after HDACi treatment. Robust antiproliferative activity was observed across all lymphoma histotypes represented. Focusing on DLBCL, we identified a low-sensitivity subset that almost exclusively consists of the oxidative phosphorylation (OxPhos)-DLBCL metabolic subtype. OxPhos-DLBCL cells also showed poorer sensitivity to other HDACis, including vorinostat. Transcriptomic analysis revealed fewer modulated transcripts but an enrichment of antioxidant pathway genes after HDACi treatment of OxPhos-DLBCLs compared with high-sensitivity B-cell receptor (BCR)-DLBCLs. Pharmacologic inhibition of antioxidant production rescued sensitivity of OxPhos-DLBCLs to pracinostat whereas BCR-DLBCLs were unaffected. Our study provides novel insights into the antilymphoma activity of pracinostat and identifies a differential response of DLBCL metabolic subtypes to HDACis.

Mitochondrial Dynamics and Liver Cancer

Simple Summary

Hepatocellular carcinoma is a leading cause of cancer-related death worldwide. Major risk factors in liver cancer development include chronic hepatitis B or C virus, autoimmune hepatitis, diabetes mellitus, alcohol abuse, and several metabolic diseases, among others. Standard therapy shows low efficacy, and there is an urgent need for novel therapies. Recent data permit to propose that proteins that control mitochondrial morphology through changes in mitochondrial fusion or mitochondrial fission, confer susceptibility or resistance to the development of liver cancer in mouse models. Here, we review the data that suggest mitochondrial dynamics to be involved in the development of liver tumors.

Abstract

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer. Due to its rising incidence and limited therapeutic options, HCC has become a leading cause of cancer-related death worldwide, accounting for 85% of all deaths due to primary liver cancers. Standard therapy for advanced-stage HCC is based on anti-angiogenic drugs such as sorafenib and, more recently, lenvatinib and regorafenib as a second line of treatment. The identification of novel therapeutic strategies is urgently required. Mitochondrial dynamics describes a group of processes that includes the movement of mitochondria along the cytoskeleton, the regulation of mitochondrial morphology and distribution, and connectivity mediated by tethering and fusion/fission events. In recent years, mitochondrial dynamic processes have emerged as key processes in the maintenance of liver mitochondrial homeostasis. In addition, some data are accumulating on the role played by mitochondrial dynamics during cancer development, and specifically on how such dynamics act directly on tumor cells or indirectly on cells responsible for tumor aggression and defense. Here, we review the data that suggest mitochondrial dynamics to be involved in the development of liver tumors.

Methanolic Fenugreek Seed Extract Induces p53-Dependent Mitotic Catastrophe in Breast Cancer Cells, Leading to Apoptosis

Purpose

The plant Trigonella foenum-graecum, well-known as fenugreek, has been shown to control type-2 diabetes, the level of cholesterol, inflammation of wounds, disorders related to gastrointestinal tracts, and cancer as well. The present study aimed to evaluate the anti-cancer potential of methanolic fenugreek seed extract (FSE) and its possible molecular mechanism of action in breast cancer cells.

Methods

The anticancer potential of FSE was evaluated in MCF-7 and SK-BR3 breast cancer cells through various cellular assays after selecting the IC₁₀, IC₂₅, IC₃₅, and IC₅₀ doses by the cell cytotoxicity assay. Furthermore, the oral acute toxicity of FSE was examined in mice, according to the guidelines of the Organization for Economic Co-operation and Development (OECD).

Results

FSE exhibited dose-dependent cytotoxicity, as the IC₅₀ was found to be 150 and 40 μg/mL for MCF-7 and SK-BR3 breast cancer cells, respectively. The cytological observations showed the typical apoptotic morphology in both of the breast cancer cells upon treatment with FSE, as it inhibited the migration and adhesion, in a dose-dependent manner. The flow cytometry analysis revealed that FSE induced a significant shift from G₂/M, and polyploidy (>G) at higher concentrations that suggested the activation of p53-mediated mitotic catastrophe, consequently leading to apoptosis. FSE induced a significant increase in the mitochondrial depolarization, ROS as well as a Bax/Bcl-2 ratio, and also exhibited the mitochondrial associated p53 signaling pathway. The in vivo acute toxicity data revealed that the oral administration of FSE did not induce any toxic effect in mice.

Conclusion

This study, for the first time, reports the mechanistic details of the anti-cancer potential of FSE. It requires a detailed analysis to understand the effect of FSE to induce the apoptosis through the multiple signaling pathways at varying concentrations. The nontoxic effect of FSE in mice suggests to utilize it safely for pharmaceutical formulations in different cancer systems.

Bergamottin and 5-Geranyloxy-7-methoxycoumarin Cooperate in the Cytotoxic Effect of Citrus bergamia (Bergamot) Essential Oil in Human Neuroblastoma SH-SY5Y Cell Line

The plant kingdom has always been a treasure trove for valuable bioactive compounds, and Citrus fruits stand out among the others. Bergamottin (BRG) and 5-geranyloxy-7-methoxycoumarin (5-G-7-MOC) are two coumarins found in different Citrus species with well-acknowledged pharmacological properties. Previously, they have been claimed to be relevant in the anti-proliferative effects exerted by bergamot essential oil (BEO) in the SH-SY5Y human neuroblastoma cells. This study was designed to verify this assumption and to assess the mechanisms underlying the anti-proliferative effect of both compounds. Our results demonstrate that BRG and 5-G-7-MOC are able to reduce the proliferation of SH-SY5Y cells, inducing apoptosis and increasing cell population in sub-G0/G1 phase. Moreover, we demonstrated the pro-oxidant activity of the two coumarins that increased reactive oxygen species and impaired mitochondrial membrane potential. From a molecular point of view, BRG and 5-G-7-MOC were able to modulate apoptosis related factors at both protein and gene levels. Lastly, we evaluated the synergistic effect of their combination, finding that the highest synergy was observed at a concentration ratio similar to that occurring in the BEO, supporting our initial hypothesis. Taken together, our results deepen the knowledge regarding the effect of BRG and 5-G-7-MOC in SH-SY5Y cells, emphasizing the relevance of their cooperation in achieving this effect.

Development and Evaluation of Paclitaxel and Curcumin Dry Powder for Inhalation Lung Cancer Treatment

Despite the effort to develop efficient targeted drug delivery for lung cancer treatment, the outcome remains unsatisfactory with a survival rate of 15% after 5 years of diagnosis. Inhalation formulation is an ideal alternative that could ensure the direct deposition of chemotherapeutics to the lungs. However, the design of an inhalable formulation that could simultaneously achieve a high local chemotherapeutic dose to the solid tumor and exert low pulmonary toxicities is a challenge, as the presence of 10–30% of chemotherapeutics in the lung is sufficient to induce toxicity. Therefore, this study aimed to develop a simple dry powder inhalation (DPI) formulation containing a model chemotherapeutic agent (paclitaxel, PTX) and a natural antioxidant (curcumin, CUR) that acts to protect healthy lung cells from injury during direct lung delivery. The co-jet-milling of CUR and PTX resulted in formulations with suitable aerosol performance, as indicated in the high fine particle fractions (FPF) (>60%) and adequate mass median aerodynamic diameter (MMAD). The CUR/PTX combination showed a more potent cytotoxic effect against lung cancer cells. This is evident from the induction of apoptosis/necrotic cell death and G2/M cell cycle arrests in both A549 and Calu-3 cells. The increased intracellular ROS, mitochondrial depolarization and reduced ATP content in A549 and Calu-3 cells indicated that the actions of CUR and PTX were associated with mitochondrial oxidative stress. Interestingly, the presence of CUR is crucial to neutralize the cytotoxic effects of PTX against healthy cells (Beas-2B), and this is dose-dependent. This study presents a simple approach to formulating an effective DPI formulation with preferential cytotoxicity towards lung cancer.

2-Oxoglutarate-dependent dioxygenases in cancer

2-Oxoglutarate-dependent dioxygenases (2OGDDs) are a superfamily of enzymes that play diverse roles in many biological processes, including regulation of hypoxia-inducible factor-mediated adaptation to hypoxia, extracellular matrix formation, epigenetic regulation of gene transcription and the reprogramming of cellular metabolism. 2OGDDs all require oxygen, reduced iron and 2-oxoglutarate (also known as α-ketoglutarate) to function, although their affinities for each of these co-substrates, and hence their sensitivity to depletion of specific co-substrates, varies widely. Numerous 2OGDDs are recurrently dysregulated in cancer. Moreover, cancer-specific metabolic changes, such as those that occur subsequent to mutations in the genes encoding succinate dehydrogenase, fumarate hydratase or isocitrate dehydrogenase, can dysregulate specific 2OGDDs. This latter observation suggests that the role of 2OGDDs in cancer extends beyond cancers that harbour mutations in the genes encoding members of the 2OGDD superfamily. Herein, we review the regulation of 2OGDDs in normal cells and how that regulation is corrupted in cancer.

Mitocanic Di- and Triterpenoid Rhodamine B Conjugates

The combination of the “correct” triterpenoid, the “correct” spacer and rhodamine B (RhoB) seems to be decisive for the ability of the conjugate to accumulate in mitochondria. So far, several triterpenoid rhodamine B conjugates have been prepared and screened for their cytotoxic activity. To obtain cytotoxic compounds with EC₅₀ values in a low nano-molar range combined with good tumor/non-tumor selectivity, the Rho B unit has to be attached via an amine spacer to the terpenoid skeleton. To avoid spirolactamization, secondary amines have to be used. First results indicate that a homopiperazinyl spacer is superior to a piperazinyl spacer. Hybrids derived from maslinic acid or tormentic acid are superior to those from oleanolic, ursolic, glycyrrhetinic or euscaphic acid. Thus, a tormentic acid-derived RhoB conjugate 32, holding a homopiperazinyl spacer can be regarded, at present, as the most promising candidate for further biological studies.

Medicinal Chemistry Targeting Mitochondria: From New Vehicles and Pharmacophore Groups to Old Drugs with Mitochondrial Activity

Interest in tumor cell mitochondria as a pharmacological target has been rekindled in recent years. This attention is due in part to new publications documenting heterogenous characteristics of solid tumors, including anoxic and hypoxic zones that foster cellular populations with differentiating metabolic characteristics. These populations include tumor-initiating or cancer stem cells, which have a strong capacity to adapt to reduced oxygen availability, switching rapidly between glycolysis and oxidative phosphorylation as sources of energy and metabolites. Additionally, this cell subpopulation shows high chemo- and radioresistance and a high capacity for tumor repopulation. Interestingly, it has been shown that inhibiting mitochondrial function in tumor cells affects glycolysis pathways, cell bioenergy, and cell viability. Therefore, mitochondrial inhibition may be a viable strategy for eradicating cancer stem cells. In this context, medicinal chemistry research over the last decade has synthesized and characterized "vehicles" capable of transporting novel or existing pharmacophores to mitochondrial tumor cells, based on mechanisms that exploit the physicochemical properties of the vehicles and the inherent properties of the mitochondria. The pharmacophores, some of which have been isolated from plants and others, which were synthesized in the lab, are diverse in chemical nature. Some of these molecules are active, while others are prodrugs that have been evaluated alone or linked to mitochondria-targeted agents. Finally, researchers have recently described drugs with well-proven safety and efficacy that may exert a mitochondria-specific inhibitory effect in tumor cells through noncanonical mechanisms. The effectiveness of these molecules may be improved by linking them to mitochondrial carrier molecules. These promising pharmacological agents should be evaluated alone and in combination with classic chemotherapeutic drugs in clinical studies.

Emerging role of NRF2 in ROS-mediated tumor chemoresistance

Chemoresistance is a central cause for the tumor management failure. Cancer cells disrupt the redox homeostasis through reactive oxygen species (ROS) regulatory mechanisms, leading to tumor progression and chemoresistance. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of neutralizing cellular ROS and restoring redox balance. Understanding the role of NRF2 in ROS-mediated chemoresistance can be helpful in the development of chemotherapy strategies with better efficiency. In this review, we sum up the roles of ROS in the development of chemoresistance to classical chemotherapy agents including cisplatin, 5-fluorouracil, gemcitabine, oxaliplatin, paclitaxel, and doxorubicin, and how to overcome ROS-mediated tumor chemoresistance by targeting NRF2. Finally, we propose that targeting NRF2 might be a promising strategy to resist ROS-driven chemoresistance and acquire better efficacy in cancer treatment.

Involvement of Mitochondrial Mechanisms in the Cytostatic Effect of Desethylamiodarone in B16F10 Melanoma Cells

Previously, we showed that desethylamiodarone (DEA), a major metabolite of the widely used antiarrhythmic drug amiodarone, has direct mitochondrial effects. We hypothesized that these effects account for its observed cytotoxic properties and ability to limit in vivo metastasis. Accordingly, we examined DEA’s rapid (3–12 h) cytotoxicity and its early (3–6 h) effects on various mitochondrial processes in B16F10 melanoma cells. DEA did not affect cellular oxygen radical formation, as determined using two fluorescent dyes. However, it did decrease the mitochondrial transmembrane potential, as assessed by JC-1 dye and fluorescence microscopy. It also induced mitochondrial fragmentation, as visualized by confocal fluorescence microscopy. DEA decreased maximal respiration, ATP production, coupling efficiency, glycolysis, and non-mitochondrial oxygen consumption measured by a Seahorse cellular energy metabolism analyzer. In addition, it induced a cyclosporine A–independent mitochondrial permeability transition, as determined by Co²⁺-mediated calcein fluorescence quenching measured using a high-content imaging system. DEA also caused outer mitochondrial membrane permeabilization, as assessed by the immunoblot analysis of cytochrome C, apoptosis inducing factor, Akt, phospho-Akt, Bad, and phospho-Bad. All of these data supported our initial hypothesis.