Antioxidant Capacity Of Cancer Cells Research Articles

Liquidambaric acid inhibits cholangiocarcinoma progression by disrupting the STAMBPL1/NRF2 positive feedback loop

BackgroundAbnormal antioxidant capacity in cancer cells is intimately linked to tumor aggressiveness. Modulating oxidative stress status and inhibiting ferroptosis represents a novel anticancer therapeutic strategy. STAM Binding Protein Like 1 (STAMBPL1), a deubiquitinase, is implicated in various malignancies, yet its function in inhibiting ferroptosis and therapeutic potential for cholangiocarcinoma (CCA) remains unexplored. Purpose: This study elucidates STAMBPL1's function in ferroptosis and evaluates liquidambaric acid (LDA) as its inhibitor for therapeutic applications. MethodsUsing bioinformatics, WB, IHC, the expression and prognostic value of STAMBPL1 in CCA tissue was detected. The carcinogenic capacity of STAMBPL1 and LDA were assessed through CCK-8, EdU, cloning, transwell, scratch, apoptosis, and cell cycle assays. Flow cytometry and fluorescence microscopy, as well as transmission electron microscopy (TEM), examines the effects of STAMBPL1 and LDA on intracellular reactive oxygen species (ROS) and changes in mitochondrial membrane potential. The tumorigenic ability of STAMBPL1 and LDA in vivo was evaluated through subcutaneous tumor model and lung metastasis model. The underlying mechanism of STAMBPL1 was explored using immunoprecipitation coupled with Mass spectrometry (IP/MS), Co-immunoprecipitation (Co-IP), GST pull-down, DNA pull-down, and Dual-luciferase reporter assays. Molecular docking simulations, SPR, DARTS and CETSA predict the putative binding site of LDA on STAMBPL1 protein. Rescue experiments further confirmed the above conclusions. ResultsThis study unveils the upregulation and oncogenic role of STAMBPL1 in CCA. Functionally, STAMBPL1 notably enhances CCA cell proliferation and metastasis while impeding ferroptosis. STAMBPL1 stabilizes NRF2, a pivotal regulator of antioxidant enzymes, through K63 deubiquitination. Elevated NRF2, stabilized by STAMBPL1 overexpression, triggers GPX4 activation and reactive oxygen species (ROS) elimination. Particularly, sites 251-436 of STAMBPL1 interact with sites 228-605 of NRF2, facilitating DUB activity and eliminating ubiquitin molecules attached to NRF2, thus protecting it from proteasome-mediated degradation. Moreover, NRF2, acting as a transcription factor, binds to the promoter region of STAMBPL1 and activates its transcription, thus forming STAMBPL1/NRF2 positive feedback loop and regulating redox homeostasis. Molecular docking and in vitro/in vivo experiments identified that LDA binds to and inhibits STAMBPL1, thereby disrupting the STAMBPL1/NRF2 positive feedback loop, consequently suppressing CCA progression. ConclusionThis study firstly reveals that STAMBPL1 promotes cholangiocarcinoma progression by upregulating NRF2, indicating that targeting the STAMBPL1/NRF2 axis is a novel therapeutic strategy. Additionally, our findings firstly suggest that LDA can bind to STAMBPL1, inhibiting NRF2 deubiquitination and offering significant therapeutic potential.

Glutathione-depleting polyprodrug nanoparticle for enhanced photodynamic therapy and cascaded locoregional chemotherapy

Nanomedicines that combine reactive oxygen species (ROS)-responsive polyprodrug and photodynamic therapy have shown great potential for improving treatment efficacy. However, the consumption of ROS by overexpressed glutathione in tumor cells is a major obstacle for achieving effective ROS amplification and prodrug activation. Herein, we report a polyprodrug-based nanoparticle that can realize ROS amplification and cascaded drug release. The nanoparticle can respond to the high level of hydrogen peroxide in tumor microenvironment, achieving self-destruction and release of quinone methide. The quinone methide depletes intracellular glutathione and thus decreases the antioxidant capacity of cancer cells. Under laser irradiation, a large amount of ROS will be generated to induce cell damage and prodrug activation. Therefore, the glutathione-depleting polyprodrug nanoparticles can efficiently inhibit tumor growth by enhanced photodynamic therapy and cascaded locoregional chemotherapy.

Raptor couples mTORC1 and ERK1/2 inhibition by cardamonin with oxidative stress induction in ovarian cancer cells.

A balance on nutrient supply and redox homeostasis is required for cell survival, and increased antioxidant capacity of cancer cells may lead to chemotherapy failure. To investigate the mechanism of anti-proliferation of cardamonin by inducing oxidative stress in ovarian cancer cells. After 24 h of drug treatment, CCK8 kit and wound healing test were used to detect cell viability and migration ability, respectively, and the ROS levels were detected by flow cytometry. The differential protein expression after cardamonin administration was analyzed by proteomics, and the protein level was detected by Western blotting. Cardamonin inhibited the cell growth, which was related to ROS accumulation. Proteomic analysis suggested that MAPK pathway might be involved in cardamonin-induced oxidative stress. Western blotting showed that cardamonin decreased Raptor expression and the activity of mTORC1 and ERK1/2. Same results were observed in Raptor KO cells. Notably, in Raptor KO cells, the effect of cardamonin was weakened. Raptor mediated the function of cardamonin on cellular redox homeostasis and cell proliferation through mTORC1 and ERK1/2 pathways.

Transient Receptor Potential Ankyrin 1 (TRPA1) Channel as a Sensor of Oxidative Stress in Cancer Cells.

Moderate levels of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), fuel tumor metastasis and invasion in a variety of cancer types. Conversely, excessive ROS levels can impair tumor growth and metastasis by triggering cancer cell death. In order to cope with the oxidative stress imposed by the tumor microenvironment, malignant cells exploit a sophisticated network of antioxidant defense mechanisms. Targeting the antioxidant capacity of cancer cells or enhancing their sensitivity to ROS-dependent cell death represent a promising strategy for alternative anticancer treatments. Transient Receptor Potential Ankyrin 1 (TRPA1) is a redox-sensitive non-selective cation channel that mediates extracellular Ca2+ entry upon an increase in intracellular ROS levels. The ensuing increase in intracellular Ca2+ concentration can in turn engage a non-canonical antioxidant defense program or induce mitochondrial Ca2+ dysfunction and apoptotic cell death depending on the cancer type. Herein, we sought to describe the opposing effects of ROS-dependent TRPA1 activation on cancer cell fate and propose the pharmacological manipulation of TRPA1 as an alternative therapeutic strategy to enhance cancer cell sensitivity to oxidative stress.

Precise Chemodynamic Therapy of Cancer by Trifunctional Bacterium-Based Nanozymes.

Chemodynamic therapy (CDT) destroys cancer cells by converting H2O2 or O2 into reactive oxygen species (ROS), but its therapeutic efficacy is restricted by the antioxidant capacity of tumor. Previous solutions focused on strengthening the nanodrugs with the ability to increase ROS production or weaken the antioxidant capacity of cancer cells. Conversely, we here develop a mild nanodrug with negligible side effects. Specifically, the Au@Pt nanozyme decorated on a bacterial surface (Bac-Au@Pt) is reported to achieve precise CDT. Due to the tumor targeting ability of bacteria and catalytic property of Au@Pt nanozyme under acidic conditions, this nanosystem can release ROS to tumor cells effectively. In addition, the interferon gamma released by T cells specifically decreases the intracellular reductants in tumor cells, while having no obvious effect on normal cells. Therefore, a low dose of Bac-Au@Pt achieves a satisfactory therapeutic efficacy to tumor cells and is nontoxic to normal cells even at their acidic components. This nanosystem enables CDT and immunotherapy to mutually benefit and improve by each other, providing a promising strategy to achieve high anticancer efficacy even with a low dose usage.

TrxR1 to promote adriamycin resistance in MCF-7 breast cancer cells by upregulating both gene expression level and enzyme activity: Reversed by shikonin.

e15070 Background: Adriamycin is one of the effective drugs commonly used in the treatment of advanced breast cancer, but its high incidence of drug resistance and cardiotoxicity limit the application of doxorubicin. Recent evidence shows that increased antioxidant capacity of cancer cells is associated with resistance to chemotherapy. Shikonin, a derivative of Lithospermum erythrorhizon Sieb.et Zucc, displays broad antitumor activity and direct cytotoxicity on various tumor cells. Our previous study shows that shikonin was enabled to directly binding and inhibiting TrxR1, which significantly downregulates intracellular ROS in cancer cells, suggesting that shikonin might be a promising drug candidate. In this study, we identified the relationship between TrxR1 and chemotherapeutic drug resistance in cancer cells and effects of shikonin with and without adriamycin on adriamycin-resistance cells. Methods: The direct DTNB reduction assay was employed to test the enzyme activity of TrxR1. Cultured ADR-resistant MCF-7 cells were assayed for their half maximal inhibitory concentration (IC50) values and apoptosis using an CCK8 assay and Annexin V-FITC/PI-labeled flow cytometry. Drug resistance was evaluated by inhibitory concentration (IC50) values and immunoblotting multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP). TrxR1 knockdown was silenced by siRNA, leading to reducing the IC50 value of ADR-resistant MCF-7 cells. Dysfunctional endoplasmic reticulum was measured by western blot analysis of endoplasmic reticulum (ER) stress signaling pathways and observation of morphology using a transmission electron microscope. Results: We found that the TrxR1 was significantly enhanced in adriamycin-resistant (ADR/MCF7) cells.Furthermore, the decreased TrxR1 function by TrxR1-knockdown or TrxR1 inhibitor piperlongumine increased MCF-7 cells sensitivity to adriamycin. Treatment of ADR/MCF7 cells with shikonin (2.5,5,10,20,40 μM) dose-dependently inhibited TrxR1 enzyme activity and the clearance of dysfunctional endoplasmic reticulum, and induced cell apoptosis. Conclusions: Our results suggest that TrxR1 is critical for adriamycin resistance in breast cancer cells(ADR/MCF7),and shikonin or other inhibitors of TrxR1 would be potential in the treatment of cancer cells with adriamycin resistance.

Reaction of carbon monoxide with cystathionine β-synthase: implications on drug efficacies in cancer chemotherapy.

Photo-activatable carbon monoxide (CO)-releasing molecules (photoCORMs), have recently provided help to identify the salutary effects of CO in human pathophysiology. Among them notable is the ability of CO to sensitize chemotherapeutic-resistant cancer cells. Findings from our group have shown CO to mitigate drug resistance in certain cancer cells by the inhibition of cystathionine β-synthase (CBS), a key regulator of redox homeostasis in the cell. Diminution of the antioxidant capacity of cancer cells leads to sensitization to reactive oxygen species-producing drugs like doxorubicin and paclitaxel upon cotreatment with CO as well as in mitigating the drug effects of cisplatin. We hypothesize that the development of CO delivery techniques for coadministration with existing cancer treatment regimens may ultimately improve clinical outcomes in cancer therapy.

The Regulation of NRF2 by Nutrient-Responsive Signaling and Its Role in Anabolic Cancer Metabolism.

The stress responsive transcription factor nuclear factor erythroid 2 p45-related factor 2, or NRF2, regulates the expression of many cytoprotective enzymes to mitigate oxidative stress under physiological conditions. NRF2 is activated in response to oxidative stress, growth factor signaling, and changes in nutrient status. In addition, somatic mutations that disrupt the interaction between NRF2 and its negative regulator Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated 1 (KEAP1) commonly occur in cancer and are thought to promote tumorigenesis. Recent Advances: While it is well established that aberrant NRF2 activation results in enhanced antioxidant capacity in cancer cells, recent exciting findings demonstrate a role for NRF2-mediated metabolic deregulation that supports cancer cell proliferation. In this review, we describe how the NRF2-KEAP1 signaling pathway is altered in cancer, how NRF2 is regulated by changes in cellular metabolism, and how NRF2 reprograms cellular metabolism to support proliferation. Future studies will delineate the NRF2-regulated processes critical for metabolic adaptation to nutrient availability, cellular proliferation, and tumorigenesis. Antioxid. Redox Signal. 00, 000-000.

Inhibition of cancer antioxidant defense by natural compounds.

All classic, non-surgical anticancer approaches like chemotherapy, radiotherapy or photodynamic therapy kill cancer cells by inducing severe oxidative stress. Even tough chemo- and radiotherapy are still a gold standard in cancer treatment, the identification of non-toxic compounds that enhance their selectivity, would allow for lowering their doses, reduce side effects and risk of second cancers. Many natural products have the ability to sensitize cancer cells to oxidative stress induced by chemo- and radiotherapy by limiting antioxidant capacity of cancer cells. Blocking antioxidant defense in tumors decreases their ability to balance oxidative insult and results in cell death. Though one should bear in mind that the same natural compound often exerts both anti-oxidant and pro-oxidant properties, depending on concentration used, cell type, exposure time and environmental conditions. Here we present a comprehensive overview of natural products that inhibit major antioxidant defense mechanisms in cancer cells and discuss their potential in clinical application.

Abstract P5-03-12: Selenocystine inhibits triple-negative breast cancer cell proliferation by inducing cell apoptosis and S-phase arrest

Abstract Introduction: Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited effective treatment options. New therapeutic approaches are urgently needed to improve the prognosis of TNBC. Reactive oxygen species (ROS) are inherent byproducts of oxidative metabolism, and forced stimulation of glucose oxidation in cancer cells raises oxidative stress and sensitizes cells to different stresses. Therefore, targeting the antioxidant capacity of cancer cells has become a promising anticancer strategy. As a redox modulator, selenocystine (SeC) has received a great deal of attention and has been shown effective against human melanoma, hormone receptor-positive breast cancer, and cancers of liver, lung and cervical in vitro. However, whether SeC exerts an anticancer effect on TNBC cells has never been explored. Methods: The dose-response effects and time course of effects of SeC on three different TNBC cell lines, MDA-MB-231, MDA-MB-436 and MDA-MB-468, were investigated in this study. Cellular viability was determined by the CCK-8 assay and cell morphology were recorded under a light microscope. Cellular apoptosis was detected using Annexin V/PI staining assay and cell cycle distribution was analyzed by flow cytometry. Results: SeC induced cell growth inhibition in all three TNBC cell lines. For 24, 48 and 72 hours of SeC treatments, the IC50 values were 40.8, 12.8 and 9.2 μM for MDA-MB-231 cells; 14.6, 5.4 and 3.0 μM for MDA-MB-436 cells; and 69.6, 29.3 and 19.9 μM for MDA-MB-468 cells. The changes of cellular morphology of TNBC cells in response to SeC treatment were similar to those cells undergoing apoptotic pathway. This result was confirmed by Annexin V/PI staining assays (Table 1). Cell cycle analysis further revealed that SeC also induced S-phase arrest in a dose-dependent manner (Table 2). Conclusion: In summary, SeC inhibited TNBC cell viability in a dose- and time-dependent manner which was attributed to the induction of apoptosis and S-phase arrest. Our finding indicates that SeC is a potential therapeutic agent for TNBC. Table 1. Apoptotic rate of TNBC cells after SeC treatment.Conc.(μM)MDA-MB-231MDA-MB-436MDA-MB-46805.8 %18.1 %26.7 %1025.5 %45.8 %60.7 %2040.1 %67.1 %70.9 %4054.7 %70.7 %74.5 % Table 2. SeC induces S-phase arrest in TNBC cells in a dose-dependent manner. Conc.(μM)G0/G1 (%)S (%)G2/M (%)MDA-MB-231016.655.927.5 1050.139.310.6 2045.548.16.4 4041.753.05.3MDA-MB-436042.127.630.3 1036.335.028.7 2034.340.725.0 4032.445.422.2MDA-MB-468059.123.717.2 1054.929.315.8 2050.135.714.2 4043.843.113.1 Citation Format: Long M, Qiu W, Wu J, Liu R, Su H. Selenocystine inhibits triple-negative breast cancer cell proliferation by inducing cell apoptosis and S-phase arrest. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-03-12.

Acetylation at lysine 71 inactivates superoxide dismutase 1 and sensitizes cancer cells to genotoxic agents.

Cancer cells are characterized by a high dependency on antioxidant enzymes to cope with the elevated rates of reactive oxygen species (ROS). Impairing antioxidant capacity in cancer cells disturbs the ROS homeostasis and exposes cancer cells to massive oxidative stress. In this study, we have discovered that superoxide dismutase 1 (SOD1), a major player in maintaining the cellular redox status, was acetylated at lysine 71. This acetylation, which was primarily deacetylated by Sirtuin 1 (SIRT1), suppressed the enzymatic activity of SOD1 via disrupting its association with copper chaperone for SOD1 (CCS). More importantly, genotoxic agents, such as camptothecin (CPT), induced SOD1 acetylation by disrupting its binding with SIRT1. CPT-induced SOD1 acetylation was stimulated by its provoked ROS, suggesting a positive feedback loop, in which ROS per se impairs the antioxidative defence of cancer cells and reinforces oxidative stress stimulated by anticancer agents. The intrinsic abundance of SOD1 acetylation varied among cancer cells, and high level of SOD1 acetylation was correlated with elevated sensitivity to CPT. Together, our findings gained mechanistic insights into how cytotoxic agents fine tune the intracellular ROS homeostasis to strengthen their anticancer effects, and suggested SOD1 acetylation as a candidate biomarker for predicting response to CPT-based chemotherapy.

Bioactive Peptides in Cancer: Therapeutic Use and Delivery Strategies

Bioactive Peptides in Cancer: Therapeutic Use and Delivery Strategies

Abstract 4555: Design and discovery of novel small molecule redox modulators as therapies for pancreatic cancer.

Abstract Pancreatic cancer is a complex disease. Late stage detection, poor prognosis, and resistance to available chemotherapeutics highlight the need to discover new and potent anticancer agents for its effective treatment. Altered cellular bioenergetics and oxidative stress are emerging hallmarks of most forms of cancer including pancreatic cancer. Cancer cells are more prone to reactive oxygen species (ROS)-mediated cell death due to their inherent elevated basal oxidative stress as compared to normal cells. Increased basal ROS levels could represent the Achilles’ heel of cancer cells. Even though cancer cells have adapted to survive in an oxidative stress environment, exogenous oxidative insults can overwhelm the adaptive antioxidant capacity of cancer cells and trigger ROS-mediated cell death We have identified a novel class of compounds that act as redox modulators and specifically induce cell death in cancer cells. Compound 3a was identified through a medium throughput screen of ∼1000 highly diverse in-house compounds and chemotherapeutic agents for their ability to alter cellular bioenergetics using XF 24 extracellular flux analyzer (Seahorse Bioscience, Billerica, MA). Further structural optimizations led to the discovery of a more potent analog, 3b that displayed anti-proliferative activities at low micromolar levels in both drug-sensitive and drug-resistant cancer cell lines. Treatment with compound 3b causes Akt activation resulting in increased cellular oxygen consumption, oxidative stress and depletion of cellular antioxidant pool in pancreatic cancer cells. Akt is a pro-survival kinase that is upregulated in several forms of human cancers. Hyperactive Akt inhibits apoptosis induced by numerous stimuli. However, Akt is unable to inhibit ROS-mediated cell death, and in fact, Akt aids in ROS-directed cell death by inducing cellular oxygen consumption, promoting ROS generation, and impairing ROS degeneration. Moreover, oxidative stress induced by 3b promoted activation of stress kinases (p38/JNK) and resulted in cancer cell apoptosis. Treatment with antioxidants was able to reduce cell death confirming ROS-mediated cytotoxicity. In conclusion, our novel class of compounds are promising leads that by exacerbating oxygen consumption, ROS production, and reducing the antioxidant capacity of cancer cells tip the balance towards activation of stress kinases that ultimately leads to cell death. Citation Format: Divya Pathania, Mario Sechi, Michele Palomba, Vanna Sanna, Francesco Berrettini, Angela Sias, Laleh Taheri, Nouri Neamati. Design and discovery of novel small molecule redox modulators as therapies for pancreatic cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4555. doi:10.1158/1538-7445.AM2013-4555

Abstract 682: Design and discovery of novel small molecule modulators of reactive oxygen species-mediated cell signaling

Abstract Oxidative stress is an important hallmark of cancer. Elevated levels of intrinsic reactive oxygen species (ROS) make tumor cells more susceptible to exogenously induced oxidative stress. Excessive oxidative insults overwhelm the adaptive antioxidant capacity of cancer cells and trigger ROS-mediated cell death. Increasing ROS production or decreasing ROS scavengers shows potential for selectively targeting tumor cells that are under persistent oxidative stress. Recently, we have discovered novel class of quinazolinediones that exert their anticancer effects by modulating ROS-mediated cell signaling.The sub-micromolar anti-proliferative properties of these compounds were demonstrated by MTT and colony formation assays in a panel of cancer cell lines of different origins. Treatment with these agents induced cell cycle arrest, and increased superoxide production in cancer cells. Furthermore, proteomics analysis of 600 target antibody array revealed that these molecules significantly affected several cell signaling pathways implicated in carcinogenesis, cancer progression, redox signaling, and cell death.In conclusion, quinazolinediones are promising lead compounds that selectively enhance ROS production and induce ROS-mediated cell death in cancer cells, and warrant further preclinical studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 682. doi:10.1158/1538-7445.AM2011-682