CoQ0-induced mitochondrial PTP opening triggers apoptosis via ROS-mediated VDAC1 upregulation in HL-60 leukemia cells and suppresses tumor growth in athymic nude mice/xenografted nude mice

Recommendations for nutritional supplements for dry eye disease: current advances

Dry eye disease (DED) represents a prevalent ocular surface disease. The development of effective nutritional management strategies for DED is crucial due to its association with various factors such as inflammation, oxidative stress, deficiencies in polyunsaturated fatty acids (PUFAs), imbalanced PUFA ratios, and vitamin insufficiencies. Extensive research has explored the impact of oral nutritional supplements, varying in composition and dosage, on the symptoms of DED. The main components of these supplements include fish oils (Omega-3 fatty acids), vitamins, trace elements, and phytochemical extracts. Beyond these well-known nutrients, it is necessary to explore whether novel nutrients might contribute to more effective DED management. This review provides a comprehensive update on the therapeutic potential of nutrients and presents new perspectives for combination supplements in DED treatment.

Redox-Cycling "Mitocans" as Effective New Developments in Anticancer Therapy

Our study proposes a pharmacological strategy to target cancerous mitochondria via redox-cycling "mitocans" such as quinone/ascorbate (Q/A) redox-pairs, which makes cancer cells fragile and sensitive without adverse effects on normal cells and tissues. Eleven Q/A redox-pairs were tested on cultured cells and cancer-bearing mice. The following parameters were analyzed: cell proliferation/viability, mitochondrial superoxide, steady-state ATP, tissue redox-state, tumor-associated NADH oxidase (tNOX) expression, tumor growth, and survival. Q/A redox-pairs containing unprenylated quinones exhibited strong dose-dependent antiproliferative and cytotoxic effects on cancer cells, accompanied by overproduction of mitochondrial superoxide and accelerated ATP depletion. In normal cells, the same redox-pairs did not significantly affect the viability and energy homeostasis, but induced mild mitochondrial oxidative stress, which is well tolerated. Benzoquinone/ascorbate redox-pairs were more effective than naphthoquinone/ascorbate, with coenzyme Q0/ascorbate exhibiting the most pronounced anticancer effects in vitro and in vivo. Targeted anticancer effects of Q/A redox-pairs and their tolerance to normal cells and tissues are attributed to: (i) downregulation of quinone prenylation in cancer, leading to increased mitochondrial production of semiquinone and, consequently, superoxide; (ii) specific and accelerated redox-cycling of unprenylated quinones and ascorbate mainly in the impaired cancerous mitochondria due to their redox imbalance; and (iii) downregulation of tNOX.

In vitro and in vivo anti-tumor activity of Coenzyme Q0 against TWIST1-overexpressing HNSCC cells: ROS-mediated inhibition of EMT/metastasis and autophagy/apoptosis induction

HNSCC (Head and Heck Squamous Cell Carcinoma) is a reasonably prevalent cancer with a high mortality rate. In this study, we tried to examine the anti-metastasis and apoptosis/autophagy actions of Coenzyme Q₀ (CoQ₀, 2,3-dimethoxy-5-methyl-1,4-benzoquinone), a derivative of Antrodia camphorata in HNCC TWIST1 overexpressing (FaDu-TWIST1) cells as well as in vivo tumor xenograft mice model. Using fluorescence based cellular assays, western blot and nude mice tumor xenografts, we determined that CoQ₀ effectively reduced cell viability and displayed rapid morphological changes in FaDu-TWIST1 cells compared to FaDu cells. Non/sub-cytotoxic concentrations of CoQ₀ treatment reduces the cell migration by downregulating TWIST1 and upregulating E-cadherin. Apoptosis produced by CoQ₀ was mostly related with caspase-3 activation, PARP cleavage, and VDAC-1 expression. The FaDu-TWIST1 cells treated with CoQ₀ exhibits autophagy-mediated LC3-II accumulation and acidic vesicular organelles (AVOs) formation. Pre-treatment with 3-MA and CoQ effectively prevented CoQ₀-induced cell death and CoQ₀-triggered autophagy in FaDu-TWIST cells as a death mechanism. CoQ₀ induces ROS production in FaDu-TWIST1 cells and NAC pre-treatment significantly reduces anti-metastasis, apoptosis, and autophagy. Likewise, ROS-mediated AKT inhibition regulates CoQ₀-induced apoptosis/autophagy in FaDu-TWIST1 cells. In vivo studies exhibit, CoQ₀ effectively delays and reduces the tumor incidence and burden in FaDu-TWIST1-xenografted nude mice. Current findings display, CoQ₀ exhibits a novel anti-cancer mechanism hence, it might be appropriate for anticancer therapy, and a new potent drug for HNSCC.

Coenzyme Q0, a novel quinone derivative of Antrodia camphorata, induces ROS-mediated cytotoxic autophagy and apoptosis against human glioblastoma cells in vitro and in vivo

Coenzyme Q0 (CoQ0, 2,3-dimethoxy-5-methyl-1,4-benzoquinone) derived from Antrodia camphorata exerts anticancer activities against breast, melanoma, and ovarian carcinoma. Glioblastoma multiforme is a common tumor affecting the central nervous system. This study explored anticancer properties of CoQ0 on human glioblastoma both in vitro and in vivo, and explained the molecular mechanism behind it. CoQ0 treatment retarded the growth and suppressed colony formation in glioblastoma (U87MG and GBM8401) cells. CoQ0 induced apoptosis by activation of caspase-3, cleavage of PARP, and dysregulation of Bax and Bcl-2 in both cell lines. Annexin V/PI staining indicated CoQ0 mediated necrosis and apoptosis. Interestingly, AVOs were increased trough induction of autophagy by CoQ0, LC3-II accumulation, and p62/SQSTM1 expression, leading to death mechanism. Z-VAD-FMK has no effect on CoQ0-induced autophagy but autophagy inhibition by 3-methyladenine (3-MA)/chloroquine (CQ) led to CoQ0-induced apoptosis. N-acetylcysteine (NAC) inhibited CoQ0-mediated ROS production and diminished CoQ0-induced apoptotic and autophagic cell death. Further, CoQ0 inhibited PI3K/AKT/mTOR signaling pathways. CoQ0 reduced the tumor burden in U87MG and GBM8401 xenografted athymic nude mice and significantly modulated tumor xenograft by inducing apoptosis and autophagy. CoQ0 generated ROS-mediated apoptotic and autophagic cell death for effective glioblastoma treatment.

Artemisinin Derivatives Inhibit Non-small Cell Lung Cancer Cells Through Induction of ROS-dependent Apoptosis/Ferroptosis

Non-small cell lung cancer (NSCLC) is one of the major cancer-related causes of morbidity and mortality worldwide. Despite the progress in lung cancer treatment, there is still an urgent need to discover novel therapeutic agents for NSCLC. Natural products represent a rich source of bioactive compounds. Through a natural compound library screening assay, we found that a group of anti-insect drugs had significant inhibitory effect on the proliferation of NSCLC cells. Among the anti-insect drugs, two derivatives of artemisinin, i.e., artesunate (ART) and dihydroartemisinin (DHA), a group of well-known anti-malarial drugs, have been shown to possess selective anti-cancer properties. Mechanistically, we found that ART and DHA induced apoptosis of A549 cells as evidenced by decreased protein level of VDAC and increased caspase 3 cleavage. Furthermore, cystine/glutamate transporter (xCT), a core negative regulator of ferroptosis, was downregulated by ART and DHA. The mRNA level of transferrin receptor (TFRC), a positive regulator of ferroptosis, was upregulated by ART and DHA. ART/DHA-induced apoptosis and ferroptosis in NSCLC cells were partly reversed by N-Acetyl-L-cysteine (NAC), a ROS scavenger, and ferrostatin-1, a ferroptosis inhibitor, respectively. These results suggest that artemisinin derivatives have anti-NSCLC activity through induction of ROS-dependent apoptosis/ferroptosis. Our findings provide the experimental basis for the potential application of artemisinin derivatives as a class of novel therapeutic drugs for NSCLC.

Vinegar/Tetramethylpyrazine Induces Nutritional Preconditioning Protecting the Myocardium Mediated by VDAC1

Vinegar is good for health. Tetramethylpyrazine (TMP) is the main component of its flavor, quality, and function. We hypothesized that vinegar/TMP pretreatment could induce myocardial protection of "nutritional preconditioning (NPC)" by low-dose, long-term supplementation and alleviate the myocardial injury caused by anoxia/reoxygenation (A/R). To test this hypothesis, TMP content in vinegar was detected by HPLC; A/R injury model was prepared by an isolated mouse heart and rat cardiomyocyte to evaluate the myocardial protection and mechanism of vinegar/TMP pretreatment by many enzymatic or functional, or cellular and molecular biological indexes. Our results showed that vinegar contained TMP, and its content was in direct proportion to storage time. Vinegar/TMP pretreatment could improve hemodynamic parameters, decrease lactate dehydrogenase (LDH) and creatine phosphokinase activities, and reduce infarct size and apoptosis in the isolated hearts of mice with A/R injury. Similarly, vinegar/TMP pretreatment could increase cell viability, decrease LDH activity, and decrease apoptosis against A/R injury of cardiomyocytes. Vinegar/TMP pretreatment could also maintain the mitochondrial function of A/R-injured cardiomyocytes, including improving oxygen consumption rate and extracellular acidification rate, reducing reactive oxygen species generation, mitochondrial membrane potential loss, mitochondrial permeability transition pore openness, and cytochrome c releasing. However, the protective effects of vinegar/TMP pretreatment were accompanied by the downregulation of VDAC1 expression in the myocardium and reversed by pAD/VDAC1, an adenovirus that upregulates VDAC1 expression. In conclusion, this study is the first to demonstrate that vinegar/TMP pretreatment could induce myocardial protection of NPC due to downregulating VDAC1 expression, inhibiting oxidative stress, and preventing mitochondrial dysfunction; that is, VDAC1 is their target, and the mitochondria are their target organelles. TMP is one of the most important myocardial protective substances in vinegar.

Taurine Antagonizes Macrophages M1 Polarization by Mitophagy-Glycolysis Switch Blockage via Dragging SAM-PP2Ac Transmethylation

The excessive M1 polarization of macrophages drives the occurrence and development of inflammatory diseases. The reprogramming of macrophages from M1 to M2 can be achieved by targeting metabolic events. Taurine promotes for the balance of energy metabolism and the repair of inflammatory injury, preventing chronic diseases and complications. However, little is known about the mechanisms underlying the action of taurine modulating the macrophage polarization phenotype. In this study, we constructed a low-dose LPS/IFN-γ-induced M1 polarization model to simulate a low-grade pro-inflammatory process. Our results indicate that the taurine transporter TauT/SlC6A6 is upregulated at the transcriptional level during M1 macrophage polarization. The nutrient uptake signal on the membrane supports the high abundance of taurine in macrophages after taurine supplementation, which weakens the status of methionine metabolism, resulting in insufficient S-adenosylmethionine (SAM). The low availability of SAM is directly sensed by LCMT-1 and PME-1, hindering PP2Ac methylation. PP2Ac methylation was found to be necessary for M1 polarization, including the positive regulation of VDAC1 and PINK1. Furthermore, its activation was found to promote the elimination of mitochondria by macrophages via the mitophagy pathway for metabolic adaptation. Mechanistically, taurine inhibits SAM-dependent PP2Ac methylation to block PINK1-mediated mitophagy flux, thereby maintaining a high mitochondrial density, which ultimately hinders the conversion of energy metabolism to glycolysis required for M1. Our findings reveal a novel mechanism of taurine-coupled M1 macrophage energy metabolism, providing novel insights into the occurrence and prevention of low-grade inflammation, and propose that the sensing of taurine and SAM availability may allow communication to inflammatory response in macrophages.

VDAC1 promotes cardiomyocyte autophagy in anoxia/reoxygenation injury via the PINK1/Parkin pathway

Ischemia/reperfusion (I/R) is a well-known injury to the myocardium, but the mechanism involved remains elusive. In addition to the well-accepted apoptosis theory, autophagy was recently found to be involved in the process, exerting a dual role as protection in ischemia and detriment in reperfusion. Activation of autophagy is mediated by mitochondrial permeability transition pore (MPTP) opening during reperfusion. In our previous study, we showed that MPTP opening is regulated by VDAC1, a channel protein located in the outer membrane of mitochondria. Thus, upregulation of VDAC1 expression is a possible trigger to cardiomyocyte autophagy via an unclear pathway. Here, we established an anoxia/reoxygenation (A/R) model in vitro to simulate the I/R process in vivo. At the end of A/R treatment, VDAC1, Beclin 1, and LC3-II/I were upregulated, and autophagic vacuoles were increased in cardiomyocytes, which showed a connection of VDAC1 and autophagy development. These variations also led to ROS burst, mitochondrial dysfunction, and aggravated apoptosis. Knockdown of VDAC1 by RNAi could alleviate the above-mentioned cellular damages. Additionally, the expression of PINK1 and Parkin was enhanced after A/R injury. Furthermore, Parkin was recruited to mitochondria from the cytosol, which suggested that the PINK1/Parkin autophagic pathway was activated during A/R. Nevertheless, the PINK1/Parkin pathway was effectively inhibited when VDAC1 was knocked-down. Taken together, the A/R-induced cardiomyocyte injury was mediated by VDAC1 upregulation, which led to cell autophagy via the PINK1/Parkin pathway, and finally aggravated apoptosis.

The Mitochondrial Permeability Transition: Nexus of Aging, Disease and Longevity

The activity of the mitochondrial permeability transition pore, mPTP, a highly regulated multi-component mega-channel, is enhanced in aging and in aging-driven degenerative diseases. mPTP activity accelerates aging by releasing large amounts of cell-damaging reactive oxygen species, Ca²⁺ and NAD⁺. The various pathways that control the channel activity, directly or indirectly, can therefore either inhibit or accelerate aging or retard or enhance the progression of aging-driven degenerative diseases and determine lifespan and healthspan. Autophagy, a catabolic process that removes and digests damaged proteins and organelles, protects the cell against aging and disease. However, the protective effect of autophagy depends on mTORC2/SKG1 inhibition of mPTP. Autophagy is inhibited in aging cells. Mitophagy, a specialized form of autophagy, which retards aging by removing mitochondrial fragments with activated mPTP, is also inhibited in aging cells, and this inhibition leads to increased mPTP activation, which is a major contributor to neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. The increased activity of mPTP in aging turns autophagy/mitophagy into a destructive process leading to cell aging and death. Several drugs and lifestyle modifications that enhance healthspan and lifespan enhance autophagy and inhibit the activation of mPTP. Therefore, elucidating the intricate connections between pathways that activate and inhibit mPTP, in the context of aging and degenerative diseases, could enhance the discovery of new drugs and lifestyle modifications that slow aging and degenerative disease.

Recent progress in the use of mitochondrial membrane permeability transition pore in mitochondrial dysfunction-related disease therapies

Mitochondria have various cellular functions, including ATP synthesis, calcium homeostasis, cell senescence, and death. Mitochondrial dysfunction has been identified in a variety of disorders correlated with human health. Among the many underlying mechanisms of mitochondrial dysfunction, the opening up of the mitochondrial permeability transition pore (mPTP) is one that has drawn increasing interest in recent years. It plays an important role in apoptosis and necrosis; however, the molecular structure and function of the mPTP have still not been fully elucidated. In recent years, the abnormal opening up of the mPTP has been implicated in the development and pathogenesis of diverse diseases including ischemia/reperfusion injury (IRI), neurodegenerative disorders, tumors, and chronic obstructive pulmonary disease (COPD). This review provides a systematic introduction to the possible molecular makeup of the mPTP and summarizes the mitochondrial dysfunction-correlated diseases and highlights possible underlying mechanisms. Since the mPTP is an important target in mitochondrial dysfunction, this review also summarizes potential treatments, which may be used to inhibit pore opening up via the molecules composing mPTP complexes, thus suppressing the progression of mitochondrial dysfunction-related diseases.

Novel sulfonamide porphyrin TBPoS-2OH used in photodynamic therapy for malignant melanoma

The application of photodynamic therapy (PDT) for the treatment of skin diseases has been receiving much attention. Here, we examined the anti-tumor effect of a novel porphyrin-based photosensitizer TBPoS-2OH in the malignant melanoma A375 and B16 cells. TBPoS-2OH has obvious cell photo-cytotoxicity, but it has low cell dark-cytotoxicity. Further research showed that TBPoS-2OH is enriched in lysosomes after being taken up by cells. Subsequently, the apoptotic rates were significantly increased in TBPoS-2OH-treated A375 and B16 cells. The specific mechanism may be that after receiving light stimulation, TBPoS-2OH could effectively increase the level of intracellular reactive oxygen species (ROS), thereby activating mitochondrial apoptosis pathway-related proteins in A375 and B16 cells. We found an increase in the content of cytochrome C in the cytoplasm, and the levels of related proteins, such as cleaved caspase-3, cleaved caspase-9, and cleaved PARP1, were significantly increased in TBPoS-2OH-treated cells. These results indicated that the new compound TBPoS-2OH could be developed and become an alternative drug for the treatment of melanoma. Some reference ideas for the development of new photosensitizers are also provided.

10H-3,6-Diazaphenothiazines triggered the mitochondrial-dependent and cell death receptor-dependent apoptosis pathways and further increased the chemosensitivity of MCF-7 breast cancer cells via inhibition of AKT1 pathways

Breast cancer is one of the leading causes of death in cancer categories, followed by lung, colorectal, and ovarian among the female gender across the world. 10H-3,6-diazaphenothiazine (PTZ) is a thiazine derivative compound that exhibits many pharmacological activities. Herein, we proceed to investigate the pharmacological activities of PTZ toward breast cancer MCF-7 cells as a representative in vitro breast cancer cell model. The PTZ exhibited a proliferation inhibition (IC50  = 0.895 µM) toward MCF-7 cells. Further, cell cycle analysis illustrated that the S-phase checkpoint was activated to achieve proliferation inhibition. In vitro cytotoxicity test on three normal cell lines (HEK293 normal kidney cells, MCF-10A normal breast cells, and H9C2 normal heart cells) demonstrated that PTZ was more potent toward cancer cells. Increase in the levels of reactive oxygen species results in polarization of mitochondrial membrane potential (ΔΨm), together with suppression of mitochondrial thioredoxin reductase enzymatic activity suggested that PTZ induced oxidative damages toward mitochondria and contributed to improved drug efficacy toward treatment. The RT2 PCR Profiler Array (human apoptosis pathways) proved that PTZ induced cell death via mitochondria-dependent and cell death receptor-dependent pathways, through a series of modulation of caspases, and the respective morphology of apoptosis was observed. Mechanistic studies of apoptosis suggested that PTZ inhibited AKT1 pathways resulting in enhanced drug efficacy despite it preventing invasion of cancer cells. These results showed the effectiveness of PTZ in initiation of apoptosis, programmed cell death, toward highly chemoresistant MCF-7 cells, thus suggesting its potential as a chemotherapeutic drug.

Flavokawain B and Doxorubicin Work Synergistically to Impede the Propagation of Gastric Cancer Cells via ROS-Mediated Apoptosis and Autophagy Pathways

Simple Summary

Among various kinds of treatment strategies for cancers, combination therapy has attracted significant attention due to its beneficial effects than the individual effects of the same compounds. Based on this idea, this study has investigated the synergistic effects of combination treatment of a natural anti-cancer agent flavokawain B (FKB) and a chemotherapeutic agent Doxorubicin on human gastric cancer cells and the underlying molecular mechanisms were deciphered through in vitro and in vivo approaches. Experimental data obtained in this study provided promising application prospects of FKB + Doxrubicin combination treatment in human gastric cancer cells.

Abstract

Chalcone flavokawain B (FKB) possesses a chemopreventive and anti-cancer activity. Doxorubicin is a chemotherapeutic DNA intercalating agent widely used in malignancy treatment. The present study investigated whether synergistic effects exist between the combination of FKB (1.25–5 µg/mL) and doxorubicin (0.5 µg/mL) on the apoptosis and autophagy in human gastric cancer (AGS) cells, and the possible in vitro and in vivo mechanisms. The MTT assay measured cell viability. Various apoptotic-, autophagy-associated protein expression was determined by the Western blot technique. FKB+doxorubicin synergy was estimated by the Chou-Talalay combination index (CI) method. In vivo studies were performed on BALB/c mice. Results showed that compared to FKB/doxorubicin treatments, low doses of FKB+doxorubicin suppressed AGS cell growth. FKB potentiated doxorubicin-induced DNA fragmentation, apoptotic cell death, and enhanced doxorubicin-mediated mitochondrial, death receptor pathways. FKB+doxorubicin activated increased LC3-II accumulation, p62/SQSTM1 expression, and AVO formation as compared to the FKB/doxorubicin alone treatments indicating autophagy in these cells. The death mechanism in FKB+doxorubicin-treated AGS cells is due to the activation of autophagy. FKB+doxorubicin-mediated dysregulated Bax/Bcl-2, Beclin-1/Bcl-2 ratios suggested apoptosis, autophagy induction in AGS cells. FKB+doxorubicin-induced LC3-II/AVOs downregulation was suppressed due to an apoptotic inhibitor Z-VAD-FMK. Whereas, 3-methyladenine/chloroquine weakened FKB+doxorubicin-induced apoptosis (decreased DNA fragmentation/caspase-3). Activation of ERK/JNK may be involved in FKB+doxorubicin-induced apoptosis and autophagy. FKB+doxorubicin-triggered ROS generation, but NAC attenuated FKB+doxorubicin-induced autophagic (LC3 accumulation) and apoptotic (caspase-3 activation and PARP cleavage) cell death. FKB+doxorubicin blocked gastric cancer cell xenografts in nude mice in vivo as compared to FKB/doxorubicin alone treatments. FKB and doxorubicin wielded synergistic anti-tumor effects in gastric cancer cells and is a promising therapeutic approach.

Utilizing Synergistic Potential of Mitochondria-Targeting Drugs for Leukemia Therapy

Acute myeloid leukemia (AML) is an aggressive group of cancers with high mortality rates and significant relapse risks. Current treatments are insufficient, and new therapies are needed. Recent discoveries suggest that AML may be particularly sensitive to chemotherapeutics that target mitochondria. To further investigate this sensitivity, six compounds that target mitochondria [IACS-010759, rotenone, cytarabine, etoposide, ABT-199 (venetoclax), and carbonyl cyanide m-chlorophenylhydrazone] were each paired with six compounds with other activities, including tyrosine kinase inhibitors (midostaurin and dasatinib), glycolytic inhibitors (2-deoxy-D-glucose, 3-bromopyruvate, and lonidamine), and the microtubule destabilizer vinorelbine. The 36 resulting drug combinations were tested for synergistic cytotoxicity against MOLM-13 and OCI-AML2 AML cell lines. Four combinations (IACS-010759 with vinorelbine, rotenone with 2-deoxy-D-glucose, carbonyl cyanide m-chlorophenylhydrazone with dasatinib, and venetoclax with lonidamine) showed synergistic cytotoxicity in both AML cell lines and were selective for tumor cells, as survival of healthy PBMCs was dramatically higher. Among these drug pairs, IACS-010759/vinorelbine decreased ATP level and impaired mitochondrial respiration and coupling efficiency most profoundly. Some of these four treatments were also effective in K-562, KU812 (chronic myelogenous leukemia) and CCRF-CEM, MOLT-4 (acute lymphoblastic leukemia) cells, suggesting that these treatments may have value in treating other forms of leukemia. Finally, two of the four combinations retained high synergy and strong selectivity in primary AML cells from patient samples, supporting the potential of these treatments for patients.

Cinobufagin induces cell cycle arrest at the S phase and promotes apoptosis in nasopharyngeal carcinoma cells

Emerging evidence suggests that cinobufagin, an active ingredient in Venenum Bufonis, inhibits cell proliferation in several tumor cells. However, the anti-tumor effect of cinobufagin on nasopharyngeal carcinoma and the underlying molecular mechanisms are still unclear. In this study, we found that cinobufagin significantly inhibits the proliferation of nasopharyngeal carcinoma HK-1 cells. Further analyses demonstrated that cinobufagin induces cell cycle arrest at the S phase in HK-1 cells through downregulating the levels of CDK2 and cyclin E. Moreover, cinobufagin significantly downregulates the protein level of Bcl-2 and upregulates the levels of Bax, subsequently increasing the levels of cytoplasmic cytochrome c, Apaf-1, cleaved PARP1, cleaved caspase-3, and cleaved caspase-9, leading to HK-1 apoptosis. Furthermore, we found that cinobufagin significantly increases ROS levels and decreases the mitochondrial membrane potential in HK-1 cells. Collectively, these data imply that cinobufagin induces cell cycle arrest at the S phase and induces apoptosis through increasing ROS levels, thereby inhibiting cell proliferation in HK-1 cells. Therefore, cinobufagin is a promising bioactive agent that may contribute to the development of treatment strategies of nasopharyngeal carcinoma.

Kalantuboside B induced apoptosis and cytoprotective autophagy in human melanoma A2058 cells: An in vitro and in vivo study

Kalantuboside B (KB), a natural bufadienolide derivative extracted from the succulent plant Kalanchoe tubiflora, is well-known for its cardiotonic, immunomodulatory, and anti-inflammatory properties. In this study, we tested in vitro and in vivo anti-cancer efficacy with low concentrations of KB (5-30 ng/mL; 8.7-52.2 nM) on A2058 melanoma cells; and for the molecular mechanisms that underlie them. KB significantly inhibited the cell viability and colony formation via arresting the cell cycle at G2/M phase. There was an association with a decrease in Cyclin A/B1, Cdc25C, and Cdc2 expressions. Further, this treatment indicated the induction of apoptosis, DNA fragmentation, cytochrome c release, and caspase-3, -8, -9, and -12 activation, and PARP cleavage, which shows that mitochondrial, death-receptor, and ER-stress signaling pathways are involved. KB-induced autophagy was apparent from enhanced LC3-II accumulation, GFP-LC3 puncta, and AVO formation. Surprisingly, KB-mediated cell death was potentiated by 3-MA and CQ to suggest the role of autophagy as a cytoprotective mechanism. Moreover, KB-treated A2058 cells enhanced intracellular ROS generation and antioxidant NAC prevented apoptosis and reversed cytoprotective autophagy. Interestingly, KB-induced apoptosis (PARP cleavage) and cytoprotective autophagy (LC3-II accumulation) were mediated by the up-regulation of the ERK signaling pathway. It was also shown that KB promoted cytoprotective autophagy by a calcium dependent-p53 downregulation pathway. In vivo data showed that KB suppressed tumor growth significantly in A2058-xenografted nude mice. A Western blot indicated cell-cycle inhibition (cyclin A reduction), apoptosis induction (PARP cleavage and Bcl-2 inhibition), and cytoprotective autophagy (LC3-II upregulation and p53 downregulation) in KB-treated A2058-xenografted mice. Our findings suggested that KB-induced ROS pathway plays a role in mediating the apoptosis and cytoprotective autophagy in human melanoma cells. Thus, KB is considered to be a putative anti-tumor agent.

The role of cholesterol metabolism in leukemia

Leukemia is a common hematological malignancy with overall poor prognosis. Novel therapies are needed to improve the outcome of leukemia patients. Cholesterol metabolism reprogramming is a featured alteration in leukemia. Many metabolic-related genes and metabolites are essential to the progress and drug resistance of leukemia. Exploring potential therapeutical targets related to cholesterol homeostasis is a promising area. This review summarized the functions of cholesterol and its derived intermediate metabolites, and also discussed potential agents targeting this metabolic vulnerability in leukemia.

Anti-EMT properties of CoQ0 attributed to PI3K/AKT/NFKB/MMP-9 signaling pathway through ROS-mediated apoptosis

Background

Breast cancer is the most prevalent cancer among women. In triple-negative breast cancer (TNBC) cells, a novel quinone derivative, coenzyme Q₀ (CoQ₀), promotes apoptosis and cell-cycle arrest. This study explored the anti-epithelial–mesenchymal transition (EMT) and antimetastatic attributes of CoQ₀ in TNBC (MDA-MB-231).

Methods

Invasion, as well as MTT assays were conducted. Lipofectamine RNAiMAX was used to transfect cells with β-catenin siRNA. Through Western blotting and RT-PCR, the major signaling pathways’ protein expressions were examined, and the biopsied tumor tissues underwent immunohistochemical and hematoxylin and eosin staining as well as Western blotting.

Results

CoQ₀ (0.5–2 μM) hindered tumor migration, invasion, and progression. Additionally, it caused MMP-2/− 9, uPA, uPAR, and VEGF downregulation. Furthermore, in highly metastatic MDA-MB-231 cells, TIMP-1/2 expression was subsequently upregulated and MMP-9 expression was downregulated. In addition, CoQ₀ inhibited metastasis and EMT in TGF-β/TNF-α-stimulated non-tumorigenic MCF-10A cells. Bioluminescence imaging of MDA-MB-231 luciferase–injected live mice demonstrated that CoQ₀ significantly inhibited metastasis of the breast cancer to the lungs and inhibited the development of tumors in MDA-MB-231 xenografted nude mice. Silencing of β-catenin with siRNA stimulated CoQ₀-inhibited EMT. Western blotting as well as histological analysis established that CoQ0 reduced xenografted tumor development because apoptosis induction, cell-cycle inhibition, E-cadherin upregulation, β-catenin downregulation, and metastasis and EMT regulatory protein modulation were observed.

Conclusions

CoQ₀ inhibited the progression of metastasis as well as EMT (in vitro and in vivo). The described approach has potential in treating human breast cancer metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1196-x) contains supplementary material, which is available to authorized users.

2,3-Dimethoxy-5-methyl-p-benzoquinone (Coenzyme Q0) Disrupts Carbohydrate Metabolism of HeLa Cells by Adduct Formation with Intracellular Free Sulfhydryl-Groups, and Induces ATP Depletion and Necrosis

2,3-Dimethoxy-5-methyl-p-benzoquinone is a common chemical structure of coenzyme Q (CoQ) that conjugates different lengths of an isoprenoid side chain at the 6-position of the p-benzoquinone ring. In a series of studies to explore the cytotoxic mechanism of CoQ homologues with a short isoprenoid side chain, we found that a CoQ analogue without an isoprenoid side chain, CoQ₀, showed marked toxicity against HeLa cells in comparison with cytotoxic homologues. Therefore, we examined the cytotoxic mechanism of CoQ₀. Different from the cytotoxic CoQ homologues that induced apoptosis, 100 µM CoQ₀ induced necrosis of HeLa cells. The CoQ₀-induced cell death was accompanied by a decrease in endogenous non-protein and protein-associated sulfhydryl (SH)-groups, but this improved with the concomitant addition of compounds with SH-groups but not antioxidants without SH-groups. In addition, UV-spectrum analysis suggested that CoQ₀ could rapidly form S-conjugated adducts with compounds with SH-groups by Michael addition. On the other hand, enzyme activities of both glyceraldehyde-3-phosphate dehydrogenase, which has a Cys residue in the active site, and α-ketoglutarate dehydrogenase complex, which requires cofactors with SH-groups, CoA and protein-bound α-lipoic acid, and CoA and ATP contents in the cells were significantly decreased by the addition of CoQ₀ but not CoQ₁. Furthermore, the decrease of an endogenous antioxidant, glutathione (GSH), by CoQ₀ treatment was much greater than the predicted increase of endogenous GSH disulfide. These results suggest that CoQ₀ rapidly forms S-conjugate adducts with these endogenous non-protein and protein-associated SH-groups of HeLa cells, which disrupts carbohydrate metabolism followed by intracellular ATP depletion and necrotic cell death.

Induction of autophagic cell death in human ovarian carcinoma cells by Antrodia salmonea through increased reactive oxygen species generation

We reported in our previously executed studies that the fermented culture broth of Antrodia salmonea (AS), a mushroom used in Taiwanese folk medicine induced reactive oxygen species (ROS)-mediated apoptosis in human ovarian carcinoma cells. In this study, we studied the anticancer efficacies of AS (0-240 μg/ml) by examining the key molecular events implicated in cell death associated with autophagy in SKOV-3 and A2780 human ovarian carcinoma cells and clarified the fundamental molecular mechanisms. Treatment of ovarian carcinoma cells with AS-induced autophagic cell death mediated by increased microtubule-associated protein LC3-II, GFP-LC3 puncta, and acidic vesicular organelle (AVO) formation. These events are linked with the activation of p62/SQSTM1, the inhibition of ATG4B, the expression of ATG7, and the dysregulation of Beclin-1/Bcl-2 (i.e., B-cell lymphoma 2). N-acetylcysteine inhibited AS-induced ROS generation, which in turn constricted AS-induced LC3 conversion, AVO formation, and ATG4B inhibition, indicating ROS-mediated autophagy cell death. In addition, the 3-methyladenine (3-MA) or chloroquine (CQ)-induced autophagy inhibition decreased AS-induced apoptosis. Additionally, apoptosis inhibition by Z-VAD-FMK, a pan-caspase inhibitor, substantially suppressed AS-induced autophagy. Furthermore, AS-inhibited HER-2/ neu and PI3K/AKT signaling pathways which were reversed by autophagy inhibitors 3-MA and CQ. Thus, A. salmonea is a potential chemopreventive agent that is capable of activating ROS-mediated autophagic cell death in ovarian carcinoma cells.

Resveratrol protects cardiomyocytes against anoxia/reoxygenation via dephosphorylation of VDAC1 by Akt-GSK3 β pathway

Our previous studies showed that the effect of resveratrol preventing mitochondrial permeability transition pore (mPTP) opening in myocardial ischemia/reperfusion injury was achieved by regulating voltage-dependent anion channel 1 (VDAC1). However, the underlying mechanism remains unclear. Previous studies demonstrated that the activity and function of VDAC1 are highly regulated by post-translational modification. In present study, we investigated whether resveratrol modulates VDAC1 phosphorylation to achieve cardioprotection and explored the signaling pathways involved. Our findings demonstrated that anoxia/reoxygenation (A/R) treatment, an ischemia/reperfusion model in vitro, enhanced VDAC1 phosphorylation in cardiomyocytes. Moreover, we found phosphorylated VDAC1 showed increased affinity to Bax, whereas interaction with hexokinase 2 (HK2) was reduced. Accordingly, the generation of reactive oxygen species increased, the mitochondrial membrane potential collapsed, mPTP opening increased and cytochrome c released into cytoplasm, thereby leading to increased apoptosis. Moreover, our data showed that pretreatment with resveratrol prior to A/R injury inhibited VDAC1 phosphorylation. Dephosphorylated VDAC1 using pretreated resveratrol promoted dissociation with Bax and binding to HK2, which subsequently protected cardiomyocytes against A/R injury. In addition, Akt and its downstream glycogen synthase kinase 3 β (GSK3β) were phosphorylated by the action of resveratrol. Akt inhibitor IV abrogated Akt-GSK3β phosphorylation and thereby abolished the dephosphorylation activity of resveratrol on VDAC1. Moreover, all resveratrol-mediated protective effects on A/R injured cardiomyocytes were abolished by Akt inhibitor IV. Taken together, our data indicated that A/R injury enhanced VDAC1 phosphorylation in cardiomyocytes, whereas pretreatment with resveratrol dephosphorylated VDAC1 through the Akt-GSK3β pathway, thereby protecting cardiomyocytes against A/R injury.