The Roles of ROS and Caspases in TRAIL-Induced Apoptosis and Necroptosis in Human Pancreatic Cancer Cells

Discovery and Mechanistic Studies of Dual-Target Hits for Carbonic Anhydrase IX and VEGFR-2 as Potential Agents for Solid Tumors: X-ray, In Vitro, In Vivo, and In Silico Investigations of Coumarin-Based Thiazoles

A dual-targeting approach is predicted to yield better cancer therapy outcomes. Consequently, a series of coumarin-based thiazoles (5a-h, 6, and 7a-e) were designed and constructed as potential carbonic anhydrase (CA) and VEGFR-2 suppressors. The inhibitory actions of the target compounds were assessed against CA isoforms IX and VEGFR-2. The assay results showed that coumarin-based thiazoles 5a, 5d, and 5e can effectively inhibit both targets. 5a, 5d, and 5e cytotoxic effects were tested on pancreatic, breast, and prostate cancer cells (PANC1, MCF7, and PC3). Further mechanistic investigation disclosed the ability of 5e to interrupt the PANC1 cell progression in the S stage by triggering the apoptotic cascade, as seen by increased levels of caspases 3, 9, and BAX, alongside the Bcl-2 decline. Moreover, the in vivo efficacy of compound 5e as an antitumor agent was evaluated. Also, molecular docking and dynamics displayed distinctive interactions between 5e and CA IX and VEGFR-2 binding pockets.

Kisspeptin decreases the adverse effects of human ovarian vitrification by regulating ROS-related apoptotic occurrences

Kisspeptin is characterized as a neuropeptide with a pivotal function in female and male infertility, and its antioxidant properties have been demonstrated. In this study, the effects of kisspeptin on the improvement of the vitrification and thawing results of human ovarian tissues were investigated. In this work, 12 ovaries from patients who underwent hysterectomy were collected laparoscopically, and then 32 samples from each of their tissues were taken. Haematoxylin and eosin (H&E) staining was performed to check the normality of the ovarian tissue and, subsequently, the samples were allocated randomly into four groups, including: (1) fresh (control), (2) vitrification, (3) vitrified + 1 μM kisspeptin, and (4) vitrified + 10 μM kisspeptin groups. After vitrification, thawing, and tissue culture processes, H&E staining for tissue quality assessment, terminal deoxynucleotidyl transferase dUTP nick end labelling assay for apoptosis evaluation, and malondialdehyde (MDA), superoxide dismutase (SOD), and ferric reducing ability of plasma tests for oxidative stress appraisal were carried out. Our histological results showed incoherency of ovarian tissue morphology in the vitrification group compared with other groups. Other findings implicated increased apoptosis rate and MDA concentration and reduced SOD activity and total antioxidant capacity (TAC) in the vitrification group compared with the control group (P < 0.05). Moreover, decreased apoptosis rate and MDA concentration, and increased TAC and SOD function were observed in the vitrification with kisspeptin groups (1 μM and 10 μM) compared with the vitrified group (P < 0.05). Our reports express that kisspeptin is an effective agent to overcome the negative effects of vitrification by regulating reactive oxygen species-related apoptotic processes.

ARHGAP15 promotes metastatic colonization in gastric cancer by suppressing RAC1-ROS pathway

The molecular mechanism of tumor metastasis, especially how metastatic tumor cells colonize in a distant site, remains poorly understood. Here we reported that ARHGAP15, a Rho GTPase activating protein, enhanced gastric cancer (GC) metastatic colonization, which was quite different from its reported role as a tumor suppressor gene in other cancers. It was upregulated in metastatic lymph nodes and significantly associated with a poor prognosis. Ectopic expression of ARHGAP15 promoted metastatic colonization of gastric cancer cells in murine lungs and lymph nodes in vivo or protected cells from oxidative-related death in vitro. However, genetic downregulation of ARHGAP15 had the opposite effect. Mechanistically, ARHGAP15 inactivated RAC1 and then decreased intracellular accumulation of reactive oxygen species (ROS), thus enhancing the antioxidant capacity of colonizing tumor cells under oxidative stress. This phenotype could be phenocopied by inhibition of RAC1 or rescued by the introduction of constitutively active RAC1 into cells. Taken together, these findings suggested a novel role of ARHGAP15 in promoting gastric cancer metastasis by quenching ROS through inhibiting RAC1 and its potential value for prognosis estimation and targeted therapy.

Cyanidin-3-O-Glucoside Induces the Apoptosis of Human Gastric Cancer MKN-45 Cells through ROS-Mediated Signaling Pathways

Cyanidin-3-O-glucoside (C3G), an active ingredient in anthocyanins, mainly exists in dark cereals. C3G was investigated for its effect on human gastric cancer (GC) cells, together with its molecular mechanism. The CCK-8 assay results showed that C3G had significant antiproliferative effects on GC cells, but it had little effect on normal cells. Western blot and flow cytometry results showed that C3G regulated the reduction of mitochondrial membrane potential and arrested the cell cycle in the G2/M phase through the AKT signaling pathway, causing the cells to undergo apoptosis. Additionally, in MKN-45 cells, C3G markedly raised intracellular reactive oxygen species (ROS) levels. The wound healing assay and Transwell assay results showed that MKN-45 cell migration was significantly inhibited. Western blot results showed that the expression of E-cadherin protein was upregulated and the expressions of β-catenin, N-cadherin, and Vimentin were downregulated. Additionally, following N-acetylcysteine treatment, the expression levels of these proteins were reduced. In conclusion, C3G caused MKN-45 cells to undergo apoptosis; arrested the cell cycle in the G2/M phase; hindered cell migration; and activated the MAPK, STAT3, and NF-κB signaling pathways, by inducing an increase in ROS levels. Thus, C3G may be a promising new medication for the treatment of GC.

Wedelolactone induces apoptosis and pyroptosis in retinoblastoma through promoting ROS generation

Retinoblastoma is a most frequently occurring primary intraocular tumor in infancy and children, highlighting the requirement to find and develop novel and more effective therapeutic approaches. Wedelolactone (WDL), a nature compound isolated from E. prostrata, exhibits multiple biological activities through regulating various signaling pathways; however, its potential influences on retinoblastoma progression are still unknown, and thus was investigated in our study, as well as the underlying mechanisms. Here, we found that WDL treatments significantly reduced the proliferation of retinoblastoma cells by inducing apoptosis and pyroptosis through increasing Caspase-3, Caspase-1, gasdermin E (GSDME) and gasdermin D (GSDMD) activation. Mitochondrial impairment and reactive oxygen species (ROS) generation were considerably up-regulated in WDL-incubated retinoblastoma cells through a dose-dependent manner. Notably, we found that ROS scavenge significantly abolished the function of WDL to provoke apoptosis and pyroptosis in retinoblastoma cell lines, revealing that ROS was required for WDL to perform its anti-cancer role in retinoblastoma. Moreover, our in vivo experiments indicated that WDL administration significantly reduced the tumor growth in the established retinoblastoma mouse models with undetectable toxicity. Collectively, these findings highlighted the potential of WDL to inhibit the growth and induce cell death of retinoblastoma in vitro and in vivo, and thereby showed promise as a therapeutic agent for the treatment of retinoblastoma.

Endoplasmic Reticulum Stress-Induced Apoptotic Effects of Novel 1-Pyrroline (3,4-Dihydro-2H-pyrrole) Derivatives on Breast Cancer Cells

Heterocyclic compounds have emerged as promising and appealing scaffolds for developing effective antitumor agents. Here, the effects of synthesized 24 different 1-pyrroline derivatives (PDs) containing substituted aryl sulfide moiety were investigated on human breast cancer cell lines. The viability of cells was assessed via MTT assay. Reactive oxygen species (ROS) generation was analyzed via fluorescent dye CM-H2DCFDA. Apoptotic cells were determined via flow cytometry. Endoplasmic reticulum (ER) stress-associated protein levels were analyzed via western blot analysis. Four of the PDs (PD-12, -14, -16 and -17) had great cytotoxic selectivity against breast cancer cells. Apoptotic cell death was induced by PDs via the generation of ROS. PDs significantly increased the GRP78, p-PEAK, p-eIF2α, and CHOP protein levels indicating ER stress in breast cancer cells. These results imply that newly synthesized PDs may be potential anticancer agents as they selectively inhibit breast cancer cells.

Autophagy, ferroptosis, pyroptosis, and necroptosis in tumor immunotherapy

In recent years, immunotherapy represented by immune checkpoint inhibitors (ICIs) has led to unprecedented breakthroughs in cancer treatment. However, the fact that many tumors respond poorly or even not to ICIs, partly caused by the absence of tumor-infiltrating lymphocytes (TILs), significantly limits the application of ICIs. Converting these immune “cold” tumors into “hot” tumors that may respond to ICIs is an unsolved question in cancer immunotherapy. Since it is a general characteristic of cancers to resist apoptosis, induction of non-apoptotic regulated cell death (RCD) is emerging as a new cancer treatment strategy. Recently, several studies have revealed the interaction between non-apoptotic RCD and antitumor immunity. Specifically, autophagy, ferroptosis, pyroptosis, and necroptosis exhibit synergistic antitumor immune responses while possibly exerting inhibitory effects on antitumor immune responses. Thus, targeted therapies (inducers or inhibitors) against autophagy, ferroptosis, pyroptosis, and necroptosis in combination with immunotherapy may exert potent antitumor activity, even in tumors resistant to ICIs. This review summarizes the multilevel relationship between antitumor immunity and non-apoptotic RCD, including autophagy, ferroptosis, pyroptosis, and necroptosis, and the potential targeting application of non-apoptotic RCD to improve the efficacy of immunotherapy in malignancy.

Understanding Necroptosis in Pancreatic Diseases

Intermediate between apoptosis and necrosis, necroptosis is a regulated caspase-independent programmed cell death that induces an inflammatory response and mediates cancer development. As our understanding improves, its role in the physiopathology of numerous diseases, including pancreatic diseases, has been reconsidered, and especially in pancreatitis and pancreatic cancer. However, the exact pathogenesis remains elusive, even though some studies have been conducted on these diseases. Its unique mechanisms of action in diseases are expected to bring prospects for the treatment of pancreatic diseases. Therefore, it is imperative to further explore its molecular mechanism in pancreatic diseases in order to identify novel therapeutic options. This article introduces recent related research on necroptosis and pancreatic diseases, explores necroptosis-related molecular pathways, and provides a theoretical foundation for new therapeutic targets for pancreatic diseases.

Synthesis and Antiproliferative Activity of Novel Imipridone–Ferrocene Hybrids with Triazole and Alkyne Linkers

Imipridones, including ONC201, ONC206 and ONC212 (which are emblematic members of this class of compounds developed by Oncoceutics) constitute a novel class of anticancer agents, with promising results in clinical trials. With the aim of increasing the ROS (reactive oxygen species) responsivity of the synthesized molecules, a set of novel ferrocene–imipridone hybrids were designed and synthesized. Our strategy was motivated by the documented interplay between the imipridone-triggered activation of TRAIL (the tumor necrosis factor-related apoptosis-inducing ligand) and mitochondrial ClpP (Caseinolytic protease P) and the ROS-mediated effect of ferrocene-containing compounds. In order to obtain novel hybrids with multitarget characters, the ferrocene moiety was tethered to the imipridone scaffold through ethynylene and 1,2,3-triazolyl linkers by using Sonogashira coupling of Cu(I)- and Ru(II)-catalyzed azide–alkyne cycloadditions. The biological activities of the new hybrids were examined by using in vitro cell viability assays on four malignant cell lines (PANC-1, A2058, EBC-1 and Fadu), along with colony formation assays on the most resistant PANC-1 cell line. Several hybrids caused a significantly greater drop in the cell viability compared to ONC201, and two of them completely overcame the resistance, with IC₅₀ values comparable to those produced by ONC201. The two most potent hybrids, but not ONC201, induced apoptosis/necrosis in PANC-1 and A2058 cells after 24 h of treatment.

Astaxanthin Sensitizes Low SOD2-Expressing GBM Cell Lines to TRAIL Treatment via Pathway Involving Mitochondrial Membrane Depolarization

Carotenoids have been suggested to have either anti- or pro-oxidative effects in several cancer cells, and those effects can trigger an unbalanced reactive oxygen species (ROS) production resulting in an apoptotic response. Our study aimed to evaluate the effect of the well-known carotenoid 3, 3′-dihydroxy-β, β’-carotene-4, 4-dione (astaxanthin, AXT) on glioblastoma multiforme (GBM) cells, especially as a pretreatment of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), that was previously shown to increase ROS and to induce apoptosis in cancer cells. We found that AXT by itself did not trigger apoptosis in four investigated GBM cell lines upon a 24 h treatment at various concentrations from 2.5 to 50 µM. However, in U251-MG and T98-MG GBM cells, pretreatment of 2.5 to 10 µM AXT sensitized cells to TRAIL treatment in a statistically significant manner (p < 0.05) while it did not affect CRT-MG and U87-MG GBM cells. We further compared AXT-sensitive U251-MG and -insensitive CRT-MG response to AXT and showed that 5 µM AXT treatment had a beneficial effect on both cell lines, as it enhanced mitochondrial potential and TRAIL treatment had the opposite effect, as it decreased mitochondrial potential. Interestingly, in U251-MG, 5 µM AXT pretreatment to TRAIL-treated cells mitochondrial potential further decreased compared to TRAIL alone cells. In addition, while 25 and 50 ng/mL TRAIL treatment increased ROS for both cell lines, pretreatment of 5 µM AXT induced a significant ROS decrease in CRT-MG (p < 0.05) while less effective in U251-MG. We found that in U251-MG, superoxide dismutase (SOD) 2 expression and enzymatic activity were lower compared to CRT-MG and that overexpression of SOD2 in U251-MG abolished AXT sensitization to TRAIL treatment. Taken together, these results suggest that while AXT acts as an ROS scavenger in GBM cell lines, it also has some role in decreasing mitochondrial potential together with TRAIL in a pathway that can be inhibited by SOD2.

Au-24 as a Potential Thioredoxin Reductase Inhibitor in Hepatocellular Carcinoma Cells

A novel TrxR inhibitor Au-24 and its inhibitory ability to hepatocellular carcinoma in vitro and in vivo is reported herein. Au-24 can suppress HepG2 cells from proliferating by lowering mitochondrial membrane potential (MMP) and increasing reactive oxygen species (ROS) levels, resulting in oxidative stress, which causes DNA damage, autophagy, cell cycle arrest, and apoptosis. This compound can also affect the normal function of apoptosis, MAPK, PI3K/AKT/mTOR, NF-κB, STAT3 signaling pathways. In vivo experiments revealed that Au-24 inhibited HepG2 tumor growth more effectively than AA1 (chloro(triethylphosphine)gold(I)) by decreasing Ki67 and CD31 protein expression and promoting tumor cell apoptosis and necrosis lesions. As a result, Au-24 was found to be a promising candidate as a TrxR inhibitor for the treatment of hepatocellular carcinoma (HCC) in both in vivo and in vitro experiments.

From Apoptosis to Necroptosis: The Death Wishes to Cancer

DNA mutation is a common event in the human body, but in most situations, it is fixed right away by the DNA damage response program. In case the damage is too severe to repair, the programmed cell death system will be activated to get rid of the cell. However, if the damage affects some critical components of this system, the genetic scars are kept and multiply through mitosis, possibly leading to cancer someday. There are many forms of programmed cell death, but apoptosis and necroptosis represent the default and backup strategy, respectively, in the maintenance of optimal cell population as well as in cancer prevention. For the same reason, the ideal approach for cancer treatment is to induce apoptosis in the cancer cells because it proceeds 20 times faster than tumor cell proliferation and leaves no mess behind. Induction of necroptosis can be the second choice in case apoptosis becomes hard to achieve, however, necroptosis finishes the job at a cost-inflammation.

Bufalin Induces Programmed Necroptosis in Triple-Negative Breast Cancer Drug-Resistant Cell Lines through RIP1/ROS-Mediated Pathway

OBJECTIVE

To explore the effect and mechanism of action of bufalin in triple-negative breast cancer (TNBC) drug-resistant cell lines.

METHODS

The normal human mammary epithelial cell line, TNBC cell line, TNBC adriamycin-resistant cell line, and TNBC docetaxel-resistant cell line were treated with different doses of bufalin (0-1,000 nmol/L) at different time points (0-72 h). Propidium iodide staining, AV-FITC/PI double staining, Hoechst 33342/PI double staining and transmission electron microscopy (TEM) were used to evaluate the death patterns of the cell lines.

RESULTS

Bufalin killed the TNBC cell line and its drug-resistant cell lines in a dose/time-dependent manner (all P<0.01). After treatment with bufalin for 24 h, the adriamycin-resistant cell line showed a co-existing pattern of necroptosis and apoptosis. However, at 48 h, necroptosis was the main manifestation. After treatment with bufalin, the expressions of tumor necrosis factor α, phospho-tumor necrosis factor receptor 1, phospho-receptor interacting protein 1 and c-caspase 3 increased (all P<0.01), the killing effect of bufalin could be mostly inhibited by NEC-1, and by z-VAD-fmk (both P<0.01). Besides, the intracellular reactive oxygen species (ROS) levels increased considerably (P<0.01), the antioxidant N-acetyl cysteine or Nec-1 could inhibit the increase of ROS level and the killing effect of bufalin (all P<0.01). The adriamycin-resistant cell line exhibited necroptosis characteristic after 48 h of bufalin treatment under TEM.

CONCLUSIONS

Bufalin could induce necroptosis through RIP1/ROS-mediated pathway to kill the drug-resistant TNBC cell lines. This finding provides critical experimental data and theoretical basis for the clinical application of bufalin to overcome the difficulties in the treatment of TNBC.

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Reactive Oxygen Species (ROS) Regulates Different Types of Cell Death by Acting as a Rheostat

Reactive oxygen species (ROS) are essential for cellular signaling and response to stress. The level of ROS and the type of ROS determine the ability of cells to undergo cell death. Furthermore, dysregulation of the antioxidant pathways is associated with many diseases. It has become apparent that cell death can occur through different mechanisms leading to the classifications of different types of cell death such as apoptosis, ferroptosis, and necroptosis. ROS play essential roles in all forms of cell death, but it is only now coming into focus that ROS control and determine the type of cell death that occurs in any given cell. Indeed, ROS may act as a rheostat allowing different cell death mechanisms to be engaged and crosstalk with different cell death types. In this review, we will describe the ROS regulatory pathways and how they control different types of cell death under normal and disease states. We will also propose how ROS could provide a mechanism of crosstalk between cell death mechanisms and act as a rheostat determining the type of cell death.

The molecular mechanism of acute liver injury and inflammatory response induced by Concanavalin A

Acute liver injury is a common but urgent clinical condition, and its underlying mechanism remains to be further elucidated. Concanavalin A (ConA)-induced liver injury was investigated in the study. Different from the caspase-dependent cell apoptosis in lipopolysaccharide/D-aminogalactose (LPS/D-GalN) induced liver injury, ConA-induced hepatocyte death was independent on caspase. Increased hepatocytic expressions of mixed lineage kinase domain like (MLKL) and receptor-interacting protein kinase 1 (RIPK1), and higher serum concentration of tumor necrosis factor-α (TNF-α) were noticed in mice with ConA-induced liver injury. Inhibition of RIPK1 protein or deletion of MLKL gene could significantly attenuate the acute liver injury and improve mice survival. Besides, the ConA treatment induced severe hepatic inflammation in wide type (WT) mice in comparison with Mlkl-/- mice, suggesting the RIPK1-MLKL-mediated hepatocellular necroptosis might participate in the process of liver injury. Moreover, mitochondrial damage associated molecular patterns (DAMPs) were subsequently released after the hepatocyte death, and further activated the p38 mitogen-activated protein kinase (MAPK) pathway, which could be reduced by deletion or inhibition of Toll-like receptor 9 (TLR9). Taken together, our research revealed that ConA-induced acute liver injury was closely related to TNF-α-mediated cell necroptosis, and inhibiting RIPK1 or deleting MLKL gene could alleviate liver injury in mice. The mitochondrial DNA released by dead hepatocytes further activated neutrophils through TLR9, thus resulting in the exacerbation of liver injury.

Detection of Oxidative Stress Induced by Nanomaterials in Cells-The Roles of Reactive Oxygen Species and Glutathione

The potential of nanomaterials use is huge, especially in fields such as medicine or industry. Due to widespread use of nanomaterials, their cytotoxicity and involvement in cellular pathways ought to be evaluated in detail. Nanomaterials can induce the production of a number of substances in cells, including reactive oxygen species (ROS), participating in physiological and pathological cellular processes. These highly reactive substances include: superoxide, singlet oxygen, hydroxyl radical, and hydrogen peroxide. For overall assessment, there are a number of fluorescent probes in particular that are very specific and selective for given ROS. In addition, due to the involvement of ROS in a number of cellular signaling pathways, understanding the principle of ROS production induced by nanomaterials is very important. For defense, the cells have a number of reparative and especially antioxidant mechanisms. One of the most potent antioxidants is a tripeptide glutathione. Thus, the glutathione depletion can be a characteristic manifestation of harmful effects caused by the prooxidative-acting of nanomaterials in cells. For these reasons, here we would like to provide a review on the current knowledge of ROS-mediated cellular nanotoxicity manifesting as glutathione depletion, including an overview of approaches for the detection of ROS levels in cells.

Calotropis gigantea stem bark extract induced apoptosis related to ROS and ATP production in colon cancer cells

Conventional chemotherapeutic agents for colorectal cancer (CRC) cause systemic side effects and eventually become less efficacious owing to the development of drug resistance in cancer cells. Therefore, new therapeutic regimens have focused on the use of natural products. The anticancer activity of several parts of Calotropis gigantea has been reported; however, the effects of its stem bark extract on inhibition of cancer cell proliferation have not yet been examined. In this study, the anticancer activity of C. gigantea stem bark extract, both alone and in combination with 5-fluorouracil (5-FU), was evaluated. A crude ethanolic extract was prepared from dry, powdered C. gigantea barks using 95% ethanol. This was then partitioned to obtain dichloromethane (CGDCM), ethyl acetate, and water fractions. Quantitative analysis of the constituent secondary metabolites and calotropin was performed. These fractions exhibited cytotoxicity in HCT116 and HT-29 cells, with CGDCM showing the highest potency in both the cell lines. A combination of CGDCM and 5-FU significantly enhanced the cytotoxic effect. Moreover, the resistance of normal fibroblast, HFF-1, cells to this combination demonstrated its safety in normal cells. The combination significantly enhanced apoptosis through the mitochondria-dependent pathway. Additionally, the combination reduced adenosine triphosphate production and increased the production of reactive oxygen species, demonstrating the mechanisms involved in the induction of apoptosis. Our results suggest that CGDCM is a promising anti-cancer agent and may enhance apoptosis induction by 5-FU in the treatment of CRC, while minimizing toxicity toward healthy cells.

Dexmedetomidine alleviated neuropathic pain in dorsal root ganglion neurons by inhibition of anaerobic glycolysis activity and enhancement of ROS tolerance

Neuropathic pain is a kind of chronic pain that is triggered or caused primarily by damage to the nervous system and neurological dysfunction. It’s known that dexmedetomidine is a new type of highly selective alpha2-adrenoceptor agonist with sedation, anti-anxiety, analgesic and other effects. However, the function and mechanism of dexmedetomidine on neuropathic pain are not clear. Rat DRG neurons were isolated and identified using immunofluorescence assay. Following treatment with H₂O₂, dexmedetomidine or ROS inhibitor (NAC), the apoptosis and ROS levels were examined by flow cytometery; apoptosis- and anaerobic glycolysis-related proteins were determined by Western blot assay; glucose consumption, pyruvic acid, lactic acid and ATP/ADP ratios were also measured. The results revealed that dexmedetomidine inhibited H₂O₂-induced apoptosis and reactive oxygen species (ROS) in rat DRG neurons and in addition, dexmedetomidine down-regulated the expression levels of anaerobic glycolysis-related proteins, significantly reduced glucose, pyruvic acid and lactic acid levels. It also increased the ATP/ADP ratio in H₂O₂-treated rat dorsal root ganglion (DRG) neurons. Moreover, we also demonstrated that ROS inhibitor (NAC) also inhibited H₂O₂-induced apoptosis and anaerobic glycolysis in rat DRG neurons. In conclusion, dexmedetomidine suppressed H₂O₂-induced apoptosis and anaerobic glycolysis activity by inhibiting ROS, in rat DRG neurons. Therefore, dexmedetomidine might play a pivotal role in neuropathic pain by the inhibition of ROS.

Calycosin induces mitochondrial-dependent apoptosis and cell cycle arrest, and inhibits cell migration through a ROS-mediated signaling pathway in HepG2 hepatocellular carcinoma cells

Calycosin is one of the main ingredients extracted from the Chinese medical herb, Radix astragali (RA). It has been shown to inhibit cell proliferation and induce apoptosis in several cancer cell lines, but the underlying mechanism remains unclear. The effects of calycosin on the proliferation and apoptosis of hepatocellular carcinoma (HCC) cells, as well as its mechanism, were investigated in this study. Cell Counting Kit-8 assay results suggested that calycosin had anti-proliferation effects on HCC in dose- and time-dependent manners, and had less cytotoxicity in normal cells. Hoechst/PI double staining and flow cytometry results showed cellular morphological changes and apoptosis after treatment of HepG2 cells with calycosin. The western blot assay showed calycosin decreased the expression of Bcl-2 and increased the expression of Bax, caspase-3, and PARP. Calycosin induced the activation of MAPK, STAT3, NF-κB, apoptosis-related proteins, and induced cell cycle arrest in the G0/G1 phase by regulating AKT. In addition, calycosin reduced the expression of TGF-β1, SMAD2/3, SLUG, and vimentin. Furthermore, phosphorylation, apoptosis, and cell migration induced by calycosin were mediated by the production of reactive oxygen species. These events could be inhibited by pretreatment with N-acetyl-L-cysteine. Calycosin resisted HCC by activating ROS-mediated MAPK, STAT3, and NF-κB signaling pathways.

Sulphamoylated Estradiol Analogue Induces Reactive Oxygen Species Generation to Exert Its Antiproliferative Activity in Breast Cancer Cell Lines

2-Methoxyestradiol (2ME), a 17β-estradiol metabolite, exerts anticancer properties in vitro and in vivo. To address 2ME’s low bioavailability, research led to the in silico design of sulphamoylated 2ME analogues. However, the role of oxidative stress induced in the activity exerted by sulphamoylated compounds remains elusive. In the current study, the influence of 2-Ethyl-17-oxoestra-1,3,5(10)-trien-3-yl sulphamate (ESE-one) on reactive oxygen species (ROS) induction and its effect on cell proliferation, as well as morphology, were assessed in breast tumorigenic cells (MCF-7 and MDA-MB-231). Fluorescent microscopy showed that sulphamoylated estradiol analogues induced hydrogen peroxide and superoxide anion, correlating with decreased cell growth demonstrated by spectrophotometry data. ESE-one exposure resulted in antiproliferation which was repressed by tiron (superoxide inhibitor), trolox (peroxyl inhibitor) and N,N′-dimethylthiourea (DMTU) (hydrogen peroxide inhibitor). Morphological studies demonstrated that tiron, trolox and DMTU significantly decreased the number of rounded cells and shrunken cells in MCF-7 and MDA-MB-231 cells induced by ESE-one. This in vitro study suggests that ESE-one induces growth inhibition and cell rounding by production of superoxide anion, peroxyl radical and hydrogen peroxide. Identification of these biological changes in cancer cells caused by sulphamoylated compounds hugely contributes towards improvement of anticancer strategies and the ROS-dependent cell death pathways in tumorigenic breast cells.

Large yellow croaker peroxiredoxin IV protect cells against oxidative damage and apoptosis

Oxidative stress and inflammation lead to cell damage and are implicated in many disease states. High concentrations of hydrogen peroxide (H₂O₂) may mediate cells apoptosis by increasing intracellular reactive oxygen species (ROS) levels. In this study, we established a LYCK-PrxIV cell line (large yellow croaker head kidney cell line stably expressing peroxiredoxin IV). The level of nitric oxide (NO), superoxide anion and hydrogen peroxide (H₂O₂) in this LYCK-PrxIV cells were significantly lower than those in control cells of LYCK-pcDNA3.1 (LYCK cell line stably transfected by pcDNA3.1 vector). Additionally, when exposed to H₂O₂, cell apoptosis was significantly alleviated in LYCK-PrxIV than in control cells. Meanwhile, the ROS level and ATP content were maintained more stable in LYCK-PrxIV than in LYCK-pcDNA3.1. The over-expression of LcPrxIV in LYCK-PrxIV cells induced a declined mRNA expression of LcCXC, LcCC, LcIL-8 and LcTNF-α2, as well as an increase of LcIL-10 mRNA expression, when compared to LYCK-pcDNA3.1. On the other hand, the expression of chemokine LcCXC, LcCC and LcTNF-a2 increased in LYCK-pcDNA3.1 after H₂O₂ stimulation, while that of LcIL-8 and LcIL-10 decreased. The regualtion of gene expression in LYCK-PrxIV cells was almost the same as that in LYCK-pcDNA3.1, but the change fold was much more moderate. These results suggest that LcPrxIV may be an indispensable ROS scavenger protecting LYCK cells against oxidative damage as well as the subsequent apoptosis and inflammatory response, which provides a clue that LcPrxIV may be an assist in fish immune response.

Hydroxychavicol sensitizes imatinib-resistant chronic myelogenous leukemia cells to TRAIL-induced apoptosis by ROS-mediated IAP downregulation

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of cytokine superfamily, induces apoptosis in a number of tumor cells through the activation of extrinsic apoptotic pathway but shows little or no cytotoxicity toward normal cells. However some tumor cells are inherently resistant to TRAIL-mediated apoptosis, which needs to be addressed to establish TRAIL as a potential chemotherapeutic drug. In this study, our aim was to manipulate TRAIL-apoptosis pathway by hydroxychavicol (HCH), a polyphenol from Piper betel leaf, for the induction of apoptosis in TRAIL resistant chronic myeloid leukemia cell. When imatinib-resistant K562 cells were treated with HCH, it made these K562 cells sensitive to TRAIL. It was observed that HCH downregulated antiapoptotic proteins XIAP and FLIP, whereas the expression of TRAIL receptors, DR4 and DR5, remains unchanged. Moreover, we observed that reactive oxygen species or ROS played a crucial role in the downregulation of FLIP and XIAP because ROS scavenger significantly reversed the decrease of XIAP, and FLIP. Ubiquitin-proteasome pathway was observed to play a crucial role in the downregulation of XIAP and FLIP, as proteasomal inhibitor MG132 significantly reversed the downregulation of XIAP and FLIP. In conclusion, this study demonstrates the combinatorial treatment of TRAIL and HCH as promising alternative therapeutic approach to treat the imatinib-resistant leukemia, which are also resistant to TRAIL.

1α,25(OH)2D3 Radiosensitizes Cancer Cells by Activating the NADPH/ROS Pathway

The radioresistance of tumors affect the outcome of radiotherapy. Accumulating data suggest that 1α,25(OH)₂D₃ is a potential anti-oncogenic molecule in various cancers. In the present study, we investigated the radiosensitive effects and underlying mechanisms of 1α,25(OH)₂D₃ in vitro and in vivo. We found that 1α,25(OH)₂D₃ enhanced the radiosensitivity of lung cancer and ovarian cancer cells by promoting the NADPH oxidase-ROS-apoptosis axis. Compared to the group that only received radiation, the survival fraction and self-renewal capacity of cancer cells treated with a combination of 1α,25(OH)₂D₃ and radiation were decreased. Both apoptosis and ROS were significantly increased in the combination group compared with the radiation only group. Moreover, N-acetyl-L-cysteine, a scavenger of intracellular ROS, reversed the apoptosis and ROS induced by 1α,25(OH)₂D₃, indicating that 1α,25(OH)₂D₃ enhanced the radiosensitivity of cancer cells in vitro by promoting ROS-induced apoptosis. Moreover, our results demonstrated that 1α,25(OH)₂D₃ promoted the ROS level via activating NADPH oxidase complexes, NOX4, p22^phox, and p47^phox. In addition, knockdown of the vitamin D receptor (VDR) abolished the radiosensitization of 1α,25(OH)₂D₃, which confirmed that 1α,25(OH)₂D₃ radiosensitized tumor cells that depend on VDR. Similarly, our study also evidenced that vitamin D₃ enhanced the radiosensitivity of cancer cells in vivo and extended the overall survival of mice with tumors. In summary, these results demonstrate that 1α,25(OH)₂D₃ enhances the radiosensitivity depending on VDR and activates the NADPH oxidase-ROS-apoptosis axis. Our findings suggest that 1α,25(OH)₂D₃ in combination with radiation enhances lung and ovarian cell radiosensitivity, potentially providing a novel combination therapeutic strategy.

The Novel gem-Dihydroperoxide 12AC3O Suppresses High Phosphate-Induced Calcification via Antioxidant Effects in p53LMAco1 Smooth Muscle Cells

The excessive intake of phosphate (Pi), or chronic kidney disease (CKD), can cause hyperphosphatemia and eventually lead to ectopic calcification, resulting in cerebrovascular diseases. It has been reported that reactive oxygen species (ROS), induced by high concentrations of Pi loading, play a key role in vascular calcification. Therefore, ROS suppression may be a useful treatment strategy for vascular calcification. 12AC3O is a newly synthesized gem-dihydroperoxide (DHP) that has potent antioxidant effects. In the present study, we investigated whether 12AC3O inhibited vascular calcification via its antioxidative capacity. To examine whether 12AC3O prevents vascular calcification under high Pi conditions, we performed Alizarin red and von Kossa staining, using the mouse aortic smooth muscle cell line p53LMAco1. Additionally, the effect of 12AC3O against oxidative stress, induced by high concentrations of Pi loading, was investigated using redox- sensitive dyes. Further, the direct trapping effect of 12AC3O on reactive oxygen species (ROS) was investigated by ESR analysis. Although high concentrations of Pi loading exacerbated vascular smooth muscle calcification, calcium deposition was suppressed by the treatment of both antioxidants and 12AC3O, suggesting that the suppression of ROS may be a candidate therapeutic approach for treating vascular calcification induced by high concentrations of Pi loading. Importantly, 12AC3O also attenuated oxidative stress. Furthermore, 12AC3O directly trapped superoxide anion and hydroxyl radical. These results suggest that ROS are closely involved in high concentrations of Pi-induced vascular calcification and that 12AC3O inhibits vascular calcification by directly trapping ROS.

Heterogeneity of chondrosarcomas response to irradiations with X-rays and carbon ions: A comparative study on five cell lines

Objectives

Chondrosarcomas are malignant bone tumors considered as resistant to radiotherapy. To unravel mechanisms of resistance, we compared biological responses of several chondrosarcomas to X-ray irradiations in normoxia and hypoxia. Since hadrontherapy with Carbon-ions gave interesting clinical outcomes, we also investigated this treatment in vitro.

Methods

Five human chondrosarcoma cell lines were used and cultured in normoxia or hypoxia. Their sensitivities to irradiations were determined by carrying out survival curves. DNA damage was monitored by γH2AX expression. Apoptosis was assessed by cell cycle analysis and Apo2.7 expression, and by evaluating PARP cleavage. Senescence was evaluated using SA β-galactosidase assay. Necrosis, and autophagy, were evaluated by RIP1 and beclin-1 expression, respectively. Mutations in relevant biological pathways were screened by whole-exome sequencing.

Results

X-ray radiations induced death in some chondrosarcomas by both apoptosis and senescence (CH2879), or by either of them (SW1353 and JJ012), whereas no death was observed in other cell lines (FS090 and 105KC). Molecularly, p21 was overexpressed when senescence was elicited. Genetic analysis allowed to identify putative genes (such as TBX3, CDK2A, HMGA2) permitting to predict cell response to irradiations. Unexpectedly, chronic hypoxia did not favor radioresistance in chondrosarcomas, and even increased the radiosensitivity of JJ012 line. Finally, we show that carbon ions triggered more DNA damages and death than X-rays.

Conclusions

Chondrosarcomas have different response to irradiation, possibly due to their strong genetic heterogeneity. p21 expression is suggested as predictive of X-ray-induced senescence. Surprisingly, hypoxia does not increase the radioresistance of chondrosarcomas, but as expected Carbon ion beams are more effective that X-rays in normoxia, whereas their efficiency was also variable depending on cell lines.

Tannic Acid Promotes TRAIL-Induced Extrinsic Apoptosis by Regulating Mitochondrial ROS in Human Embryonic Carcinoma Cells

: Human embryonic carcinoma (EC; NCCIT) cells have self-renewal ability and pluripotency. Cancer stem cell markers are highly expressed in NCCIT cells, imparting them with the pluripotent nature to differentiate into other cancer types, including breast cancer. As one of the main cancer stem cell pathways, Wnt/β-catenin is also overexpressed in NCCIT cells. Thus, inhibition of these pathways defines the ability of a drug to target cancer stem cells. Tannic acid (TA) is a natural polyphenol present in foods, fruits, and vegetables that has anti-cancer activity. Through Western blotting and PCR, we demonstrate that TA inhibits cancer stem cell markers and the Wnt/β-catenin signaling pathway in NCCIT cells and through a fluorescence-activated cell sorting analysis we demonstrated that TA induces sub-G1 cell cycle arrest and apoptosis. The mechanism underlying this is the induction of mitochondrial reactive oxygen species (ROS) (mROS), which then induce the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated extrinsic apoptosis pathway instead of intrinsic mitochondrial apoptosis pathway. Moreover, ribonucleic acid sequencing data with TA in NCCIT cells show an elevation in TRAIL-induced extrinsic apoptosis, which we confirm by Western blotting and real-time PCR. The induction of human TRAIL also proves that TA can induce extrinsic apoptosis in NCCIT cells by regulating mROS.

Screening of X-ray responsive substances for the next generation of radiosensitizers

X-ray responsivity resulting in the generation of reactive oxygen species (ROS) was investigated in 9600 organic compounds that were selected by considering their structural diversity. We focused on superoxides that were primarily detected using dihydroethidium (DHE) and hydroxyl radicals, that were identified fluorometrically using 3'-(p-aminophenyl) Fluorescein (APF). Many organic compounds were discovered that responded to the DHE and/or APF assay using X-ray irradiation. These results suggest that some of these organic compounds emit either superoxides or hydroxyl radicals whereas others emit both under the influence of X-ray irradiation. The response of the derivatives of a hit compound with a partial change in the structure was also investigated. The products produced from DHE by X-ray irradiation were identified by HPLC to confirm the integrity of the process. Although, the reactions were suppressed by the superoxide dismutase (SOD), not only 2-hydroxyethidium (2-OH-E⁺), but also ethidium (E⁺) were detected. The results suggest that apart from a direct reaction, an indirect reaction may occur between DHE and the superoxides. Although X-ray responsiveness could not be inferred due to the molecular complexity of the investigated compounds, delineation of these reactions will facilitate the development of the next generation of radiosensitizers.

Mitochondrial respiratory chain dysfunction mediated by ROS is a primary point of fluoride-induced damage in Hepa1-6 cells

To evaluate the mechanism of fluoride (F) mitochondrial toxicity, we cultured Hepa1-6 cells with different F concentrations (0, 1 and 2 mmoL/L) and determined cell pathological morphology, mitochondrial respiratory chain damage and cell cycle change. Results showed that the activities and mRNA expression levels of antioxidant enzymes considerably decreased, whereas the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and nitric oxide (NO) markedly increased. Breakage of mitochondrial cristae and substantial vacuolated mitochondria were observed by transmission electron microscopy. These results indicate the F-induced oxidative damage in Hepa1-6 cells. The enzyme activities of mitochondrial complexes I, II, III and IV were disordered in Hepa1-6 cells treated by excessive F, thereby indicating a remarkable down-regulation. Further research showed that complex subunits also demonstrated the development of disorder, in which the protein expressions levels of NDUFV2 and SDHA were substantially down-regulated, whereas those of CYC1 and COX Ⅳ were markedly up-regulated. Reductions in ATP and mitochondrial membrane potential were detected with the dysfunction of the mitochondrial respiratory chain. The G2/M phase arrest of the cell cycle in Hepa1-6 cells was measured via flow cytometry, and the up-regulated protein expressions of Cyt c, caspase 9, caspase 3 and substantial apoptotic cells were determined. In summary, this study demonstrated that ROS-mediated mitochondrial respiratory chain dysfunction causes F-induced Hepa1-6 cell damage.

Functional Synergy Of Antimicrobial Peptides And Chlorhexidine Acetate Against Gram-Negative/Gram-Positive Bacteria And A Fungus In Vitro And In Vivo

Background and purpose

To reduce the resistance and allergic reaction to chlorhexidine acetate (CHA) in the current treatment of (Bacterial vaginosis) BV and (vulvovaginal candidiasis) VVC in female vaginitis. In this study, the antimicrobial activities and mechanism of action of the synergistic effects of antimicrobial peptides (AMPs) HPRP-A1 and HPRP-A2, and CHA, against Gram-negative and Gram-positive bacteria, and one fungus Candida albicans (C. albicans) were investigated in vitro and in mouse and rat vaginitis infection models in vivo.

Results

HPRP-A1, HPRP-A2 and CHA showed significant synergistic effects on the antimicrobial activities against different Gram-negative and Gram-positive bacteria and C. albicans. The combined application of HPRP-A2 and CHA exhibited strong synergistic effects in the mouse and rat vaginitis models caused by bacteria or C. albicans.

Conclusion

This study may prompt the development of new drug combinations against vaginitis infections, including mixed bacterial and fungal infections and multi-drug-resistant infections.

Synergistic effect of the pro-apoptosis peptide kla-TAT and the cationic anticancer peptide HPRP-A1

In this study, a peptide-peptide co-administration therapy between hybrid peptide kla-TAT and cationic anticancer peptide HPRP-A1 was designed to increase the anticancer activity of the combination peptides through synergistic effect. kla is a pro-apoptotic peptide which could induce rapid cancer cell apoptosis by disruption the mitochondrial membrane when internalized the cells. To enhance more kla peptides pass through cell membrane, a double improvement strategy was designed by chemically conjugation with cell penetration peptide TAT as well as co-administration with cationic membrane active peptide HPRP-A1, and the double anticancer mechanism of the kla-TAT peptide and HPRP-A1 including membrane disruption and apoptosis induction was verified through in vitro experiments. The CompuSyn synergism/antagonism analysis showed that kla-TAT acted synergistically with HPRP-A1 against a non-small cell lung cancer (NSCLC) A549 cell line. The anticancer activities of the two peptides were dramatically increased by co-administration, under the mechanism of cell membrane disruption, caspase-dependent apoptosis induction, as well as cyclin-D1 down-regulation based G1 phase arrest. We believe that the synergic therapeutic strategy would be a meaningful method for the anticancer peptides used in cancer treatment.

Programmed necrosis and its role in management of breast cancer

Breast cancer is one of the major causes of cancer related deaths in women worldwide. A major factor responsible for treatment failure in breast cancer is the development of resistance to commonly used chemotherapeutic drugs leading to disease relapse. Several studies have shown dysregulation of molecular machinery of apoptosis, the major programmed cell death pathway in breast malignancies. Thus, there is an unmet need to search for an alternative cell death pathway which can work when apoptosis is compromised. Necroptosis or programmed necrosis is a relatively recently described entity which has attracted attention in this context. Classically, even in physiological conditions necroptosis is found to act if apoptosis is not functional due to some reason. Recently, more and more studies are being conducted in different malignancies to explore the possibility and utility of inducing cell death by necroptosis. The present review describes the key molecular players involved in necroptotic pathway and their status in breast cancer. In addition, the research done to utilize this pathway for treatment of breast cancer has also been highlighted.

3-Bromopyruvate potentiates TRAIL-induced apoptosis in human colon cancer cells through a reactive oxygen species- and caspase-dependent mitochondrial pathway

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a promising anticancer cytokine with minimal toxicity towards normal cells. Nevertheless, most primary cancers are often intrinsically TRAIL-resistant or can acquire resistance after TRAIL therapy. This study aimed to investigate the inhibitory effect of co-treatment of 3-bromopyruvate (3-BP) as a potent anticancer agent with TRAIL on colon cancer cells (HT-29). The results of present study indicated that combined treatment with 3-BP and TRAIL inhibited the proliferation of HT-29 cells to a greater extent (88.4%) compared with 3-BP (54%) or TRAIL (11%) treatment alone. In contrast, the combination of 3-BP and TRAIL had no significant inhibitory effect on the proliferation of normal cells (HEK-293) (8.4%). At a cellular mechanistic level, the present study showed that 3-BP sensitized human colon cancer cells to TRAIL-induced apoptosis via reactive oxygen species generation, upregulation of Bax, downregulation of Bcl-2 and survivin, release of cytochrome c into the cytosol, and activation of caspase-3. In normal cells, 3-BP, TRAIL, or combination of both had no significant effect on the reactive oxygen species levels, release of cytochrome c, and caspase-3 activity. Therefore, the combination of 3-BP and TRAIL can be a promising therapeutic strategy for treatment of colon cancer.

Curcumin relieves paraquat‑induced lung injury through inhibiting the thioredoxin interacting protein/NLR pyrin domain containing 3‑mediated inflammatory pathway

When paraquat (PQ) enters the human body, it increases oxidative stress and inflammation, ultimately resulting in acute lung injury (ALI). Curcumin, a naturally occurring compound, has been reported to ameliorate PQ-induced ALI; however, the underlying molecular mechanisms remain unclear. In the present study, normal lung fibroblasts (WI-38VA13) were treated with 10 µmol/l PQ for 48 h, followed by a further 48 h incubation with 300 µmol/l curcumin. Cells were then harvested to determine their viability. Flow cytometry was performed to analyze the levels of reactive oxygen species (ROS) and the rate of apoptosis. The levels of apoptotic proteins and activation of the thioredoxin interacting protein/NLR pyrin domain containing 3 (TXNIP/NLRP3) axis were measured via reverse transcription-quantitative polymerase chain reaction and western blot analyses. Proinflammatory cytokine levels were examined using enzyme-linked immunosorbent assays. Finally, the expression levels of Notch1, extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphorylated-ERK1/2 were evaluated via western blotting. Following treatment with curcumin, PQ-induced increases in ROS levels and apoptosis were significantly attenuated, and Bcl-2 expression levels were upregulated, whereas those of Bax were downregulated. It was also observed that curcumin treatment downregulated the expression levels of TXNIP, NLRP3, interleukin (IL)-1β and IL-18, and downstream caspase-1 compared with PQ treatment alone. Curcumin significantly attenuated the upregulation of Notch1 without affecting ERK1/2 phosphorylation. The present findings suggested that the inhibitory effects of curcumin on TXINP1 may inhibit activation of the NLRP3 inflammasome, subsequently suppressing the upregulation of proinflammatory cytokines and ultimately improving PQ-induced ALI.

Cardiac glycoside sensitized hepatocellular carcinoma cells to TRAIL via ROS generation, p38MAPK, mitochondrial transition, and autophagy mediation

A major concern in the clinical application of tumor necrosis factor related apoptosis-inducing ligand (TRAIL) in tumors is the development of resistance. Therefore, agents that can potentially restore TRAIL sensitivity are important therapeutic targets for cancer treatment. Herein, we evaluated lanatoside c and digoxin, both of which are widely used cardiac glycosides (CGs), for their ability to sensitize human hepatocellular carcinoma cells (Huh-7 and HepG2) through TRAIL-induced apoptosis. CGs functionalize TRAIL as shown by its effect on intracellular reactive oxygen species (ROS) generation, which damages mitochondrial integrity and thereby confers intrinsic apoptotic caspase cascade during combined treatment. Caspase activation is dependent on ROS as shown by the ability of CGs to generate ROS and the ROS-N-acetylcysteine (NAC) relationship, which inhibits apoptosis during cotreatment by preventing the formation of caspase-8 and -3. Furthermore, CGs triggered p38MAPK phosphorylation and NAC pre-exposure blocked p38MAPK phosphorylation, which demonstrated that p38MAPK was dependent upon ROS generation. Additionally, CGs were found to be potent inducers of AMPK-mediated protective autophagy as pharmacological and genetic autophagy inhibition reached the higher threshold of TRAIL-mediated apoptosis. Finally, CGs downregulated the expression of the antiapoptotic protein Bcl-2 and increased the translocation of proapoptotic protein cytochrome c, thereby inducing apoptosis. Collectively, these results indicate that CGs potentiate the enhanced cytotoxic capacity to TRAIL through ROS generation, p38MAPK phosphorylation, cell survival protein downregulation, and protective autophagy inhibition.

Tumor Homing Reactive Oxygen Species Nanoparticle for Enhanced Cancer Therapy

Multifunctional nanoparticles that carry chemotherapeutic agents can be innovative anticancer therapeutic options owing to their tumor-targeting ability and high drug-loading capacity. However, the nonspecific release of toxic DNA-intercalating anticancer drugs from the nanoparticles has significant side effects on healthy cells surrounding the tumors. Herein, we report a tumor homing reactive oxygen species nanoparticle (THoR-NP) platform that is highly effective and selective for ablating malignant tumors. Sodium nitroprusside (SNP) and diethyldithiocarbamate (DDC) were selected as an exogenous reactive oxygen species (ROS) generator and a superoxide dismutase 1 inhibitor, respectively. DDC-loaded THoR-NP, in combination with SNP treatment, eliminated multiple cancer cell lines effectively by the generation of peroxynitrite in the cells (>95% cell death), as compared to control drug treatments of the same concentration of DDC or SNP alone (0% cell death). Moreover, the magnetic core (ZnFe₂O₄) of the THoR-NP can specifically ablate tumor cells (breast cancer cells) via magnetic hyperthermia, in conjunction with DDC, even in the absence of any exogenous RS supplements. Finally, by incorporating iRGD peptide moieties in the THoR-NP, integrin-enriched cancer cells (malignant tumors, MDA-MB-231) were effectively and selectively killed, as opposed to nonmetastatic tumors (MCF-7), as confirmed in a mouse xenograft model. Hence, our strategy of using nanoparticles embedded with ROS-scavenger-inhibitor with an exogenous ROS supplement is highly selective and effective cancer therapy.

The role of necroptosis in cancer biology and therapy

Apoptosis resistance is to a large extent a major obstacle leading to chemotherapy failure during cancer treatment. Bypassing the apoptotic pathway to induce cancer cell death is considered to be a promising approach to overcoming this problem. Necroptosis is a regulated necrotic cell death modality in a caspase-independent fashion and is mainly mediated by Receptor-Interacting Protein 1 (RIP1), RIP3, and Mixed Lineage Kinase Domain-Like (MLKL). Necroptosis serves as an alternative mode of programmed cell death overcoming apoptosis resistance and may trigger and amplify antitumor immunity in cancer therapy.The role of necroptosis in cancer is complicated. The expression of key regulators of the necroptotic pathway is generally downregulated in cancer cells, suggesting that cancer cells may also evade necroptosis to survive; however, in certain types of cancer, the expression level of key mediators is elevated. Necroptosis can elicit strong adaptive immune responses that may defend against tumor progression; however, the recruited inflammatory response may also promote tumorigenesis and cancer metastasis, and necroptosis may generate an immunosuppressive tumor microenvironment. Necroptosis also reportedly promotes oncogenesis and cancer metastasis despite evidence demonstrating its antimetastatic role in cancer. In addition, necroptotic microenvironments can direct lineage commitment to determine cancer subtype development in liver cancer. A plethora of compounds and drugs targeting necroptosis exhibit potential antitumor efficacy, but their clinical feasibility must be validated.Better knowledge of the necroptotic pathway mechanism and its physiological and pathological functions is urgently required to solve the remaining mysteries surrounding the role of necroptosis in cancer. In this review, we briefly introduce the molecular mechanism and characteristics of necroptosis, the interplay between necroptosis and other cell death mechanisms, crosstalk of necroptosis and metabolic signaling and detection methods. We also summarize the intricate role of necroptosis in tumor progression, cancer metastasis, prognosis of cancer patients, cancer immunity regulation, cancer subtype determination and cancer therapeutics.

Tumor necrosis factor receptor-associated protein 1 regulates hypoxia-induced apoptosis through a mitochondria-dependent pathway mediated by cytochrome c oxidase subunit II

Background

Tumor necrosis factor receptor-associated protein 1 (TRAP1) plays a protective effect in hypoxic cardiomyocytes, but the precise mechanisms are not well clarified. The study is aimed to identify the mechanism of TRAP1 on hypoxic damage in cardiomyocytes.

Methods

In this study, the effects of TRAP1 and cytochrome c oxidase subunit II (COXII) on apoptosis in hypoxia-induced cardiomyocytes were explored using overexpression and knockdown methods separately.

Results

Hypoxia induced cardiomyocyte apoptosis, and TRAP1 overexpression notably inhibited apoptosis induced by hypoxia. Conversely, TRAP1 silencing promoted apoptosis in hypoxic cardiomyocytes. Further investigation revealed that the proapoptotic effects caused by the silencing of TRAP1 were prevented by COXII overexpression, whereas COXII knockdown reduced the antiapoptotic function induced by TRAP1 overexpression. Additionally, changes in the release of cytochrome c from mitochondria into the cytosol and the caspase-3 activity in the cytoplasm, as well as reactive oxygen species production, were found to be correlated with the changes in apoptosis.

Conclusions

The current study uncovered that TRAP1 regulates hypoxia-induced cardiomyocyte apoptosis through a mitochondria-dependent apoptotic pathway mediated by COXII, in which reactive oxygen species presents as an important component.

Electronic supplementary material

The online version of this article (10.1186/s41038-019-0154-3) contains supplementary material, which is available to authorized users.

Effect of astaxanthin on apoptosis of rat renal tubular epithelial cells induced by iohexol

Contrast acute kidney injury refers to acute renal failure due to the application of contrast agents. Astaxanthin, as an antioxidant, can improve early acute kidney injury in severely burned rats. However, the mechanism of astaxanthin for renal protection is still unclear. In this study, the rat renal tubular epithelial cells (NRK-52E) were treated with iohexol, astaxanthin, astaxanthin plus nicotinamide and nicotinamide. Subsequently, the nuclear morphology was observed by fluorescence staining of DAPI DNA, the apoptosis was detected by flow cytometry, the mitochondrial membrane potential was detected by JC-1 and the SIRT1, P53, Bax, Bcl-2 protein expression level was detected by Western blotting. We found that astaxanthin can reduce nuclear pyknosis and nuclear deep staining, decrease the number of apoptotic cells, up-regulate the expression of proapoptotic proteins P53 and Bax and up-regulate the expression of anti-apoptotic protein Bcl-2 by increasing SIRT1 expression level, thereby exerting protective effects on renal tubular epithelial cells. At the same time, nicotinamide has the opposite effect on the NRK-52E compared with astaxanthin. These results indicated that astaxanthin may provide a new option for the prevention of contrast-induced acute kidney injury.

PGC-1α protects against oxidized low-density lipoprotein and luteinizing hormone-induced granulosa cells injury through ROS-p38 pathway

Obese women with polycystic ovary syndrome (PCOS) often suffer from ovulation failure, which may be driven by granulosa cells (GCs) injury caused by increased levels of circulating oxidized low-density lipoprotein (ox-LDL) and luteinizing hormone (LH). PGC-1α may play an important role in this pathophysiological processes. However, the effect and the potential mechanism of PGC-1α on GCs injury evoked by obese PCOS is fully unclear. To investigate the protective effect and the potential mechanism of PGC-1α on GCs injury evoked by ox-LDL + LH stimulation. Patients with PCOS and women of normal reproductive age who undergoing egg retrievals and consenting for this research were collected. Those women were divided into normal-weight non-PCOS group, obese non-PCOS group, normal-weight PCOS group and obese PCOS group according to the body mass index (BMI) and PCOS diagnosis. Follicular fluid was collected and primary GCs were isolated. The levels of LH and ox-LDL in follicular fluid in the four groups were measured. And, the expressions of PGC-1α, cell apoptosis and ROS generation in primary GCs in the four groups were evaluated. After GCs from women of normal reproductive age at normal-weight pre-treated with adenovirus encoding PGC-1α (Ad-PGC-1α) prior to ox-LDL + LH treatment in vitro, the cell viability, apoptosis, apoptosis-related proteins expressions and ROS generation were evaluated by CCK-8 assay, AnnexinV/PI double staining, Western blot and H₂DCF-DA staining, respectively. The expression of PGC-1α was significantly decreased, whereas the cell apoptosis and ROS generation were significantly increased in GCs of PCOS group, especially obese PCOS group. Our data also revealed that over-expression of PGC-1α in GCs from women of normal reproductive age at normal-weight markedly inhibited cell injury, ROS generation and p38 activation, accompanied by increased Bcl-2 expression, decreased Bax and cleaved caspase-3 expressions induced by ox-LDL + LH stimulation. Ox-LDL + LH-induced cell apoptosis was abrogated by attenuation of ROS generation or p38 activation. Attenuation of ROS generation reversed ox-LDL + LH-induced p38 activation, however, p38 inhibitors had an effect on ROS generation. Our findings suggested that PGC-1α protected against ox-LDL + LH-induced GCs injury through inhibiting cell apoptosis. And, the mechanism may be related to the inhibition of ROS-initiated p38 pathway. Our data indicated that PGC-1α may be a potential therapeutic target for obese PCOS.

Inhibiting TrxR suppresses liver cancer by inducing apoptosis and eliciting potent antitumor immunity

Liver cancer is one of the most common malignant tumors worldwide. Thioredoxin reductase (TrxR) is highly expressed in liver cancer cells. The present study aimed to investigate the effect of inhibiting TrxR on liver cancer and to better understand the underlying molecular and immuno-logical mechanisms associated with inhibition. It was demonstrated that targeting TrxR inhibited the growth and induced apoptosis of liver cancer cells, which was accompanied by activation of the mitogen associated protein kinase pathway. This inhibition was dependent on the production of reactive oxygen species (ROS). Blockage of ROS production reversed TrxR inhibitor‑induced antitumor effects. Blocking the Trx/TrxR system activated the mammalian target of rapamycin pathway and inhibited autophagy, which occurred in a ROS‑independent manner. TrxR inhibition led to lesions in the mitochondrial membrane, indicated by alterations in membrane potential. Mouse xenograft experiments were highly consistent with in vitro studies. Most importantly, blocking the Trx/TrxR system improved the tumor immune microenvironment. Together, these data demonstrated that TrxR is a potential target for liver cancer therapy, which could inhibit hepatocarcinogenesis and progression, and improve the antitumor immune response.

Aloe-Emodin Induces Endoplasmic Reticulum Stress-Dependent Apoptosis in Colorectal Cancer Cells

BACKGROUND Recently, colorectal cancer has become a more common type of tumor in the world. Research has reported that several kinds of single compounds of Chinese herbs have shown anti-tumor activity in colorectal cancer. Aloe-emodin (AE), a natural compound extract from Aloe Vera, has been discovered to suppress cell proliferation and accelerate apoptosis in a variety of tumor cells. Whether AE exerts an effect on colorectal cancer cells has not yet been investigated. MATERIAL AND METHODS In this study, we examined the impact of AE on SW620 and HT29 colorectal cancer cell lines. After treatment with various concentrations of AE (10, 20, and 40 μM), cell proliferation, cell apoptosis, reactive oxygen species (ROS) generation, cytosolic calcium level, and related gene expression were analyzed. RESULTS Our results indicated that AE suppressed cell viability and induced cell apoptosis in SW620 and HT29 cell lines. Furthermore, both cell lines when exposed to AE generated ROS, which induces endoplasmic reticulum (ER) stress. We then detected the expression of ER stress-related proteins and cytosolic calcium levels. We found that cells exposure to AE had upregulation of unfolded protein response (UPR) proteins like glucose-related protein 78 (GRP78), phosphorylated protein kinase R (PKR)-like ER kinase (p-PERK), phosphorylated eukaryotic initiation factor-2α (p-eIF2α), and transcription factor C/EBP homologous protein (CHOP). Meanwhile, we detected an increased cytosolic calcium content followed by the upregulation of the calpain-1, calpain-2 and caspase-12. CHOP and caspase-12 are important regulatory factors leading to cell apoptosis. CONCLUSIONS AE might serve as a candidate in the treatment of colorectal cancer through inducing ER stress-dependent apoptosis.

Antioxidative CXXC Peptide Motif From Mesencephalic Astrocyte-Derived Neurotrophic Factor Antagonizes Programmed Cell Death

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a potent survival-promoting protein with neurorestorative effect for neurodegenerative diseases. Its mechanism of action, albeit poorly known, depends strongly on the CXXC motif (CKGC). Here we studied the survival-promoting properties of the CKGC tetrapeptide from MANF. In the Jurkat T lymphocytic cell line, CKGC potently inhibits death receptor Fas-induced apoptosis and mildly counteracts mitochondrial apoptosis and necroptosis. The peptide with serines instead of cysteines (SKGS) has no survival-promoting activity. The cytoprotective efficiency of the peptide against Fas-induced apoptosis is significantly improved by reduction of its cysteines by dithiotreitol, suggesting that it protects the cells via cysteine thiol groups, partially as an antioxidant. CKGC neutralizes the reactive oxygen species, maintains the mitochondrial membrane potential and prevents activation of the effector caspases in the Jurkat cells with activated Fas. The peptide does not require intracellular administration, as it is endocytosed and resides mainly in the Golgi. Finally, the peptide also potently promotes survival of cultured primary dopaminergic neurons.

SYKT Alleviates Doxorubicin-Induced Cardiotoxicity via Modulating ROS-Mediated p53 and MAPK Signal Pathways

Backgrounds. Doxorubicin (DOX) is an effective therapeutic drug for malignant tumors; however, its clinical applications were limited by its side effects, especially the cardiotoxicity caused by ROS-mediated p53 and MAPK signal pathways' activation-induced cell apoptosis. Sanyang Xuedai mixture (SYKT) has been reported as an antioxidant agent and attenuated DOX-induced cardiotoxicity by targeting ROS-mediated apoptosis, but the mechanisms are still not fully delineated. Objective. This study aimed at investigating whether SYKT alleviated DOX-induced cardiotoxicity by inhibiting ROS-mediated apoptosis and elucidating the role of ROS-mediated p53 and MAPK signal pathways' activation in this process. Materials and Methods. Identification, separation, and culture of mouse primary cardiomyocytes. Cells were treated with DOX (1 μM), SYKT (30 mg/mL), or SYKT coupled with DOX. The p53 inhibitor Pifithrin-α (PFT-α), p38/MAPK inhibitor SB203583 (SB), and JNK inhibitor SP600125 (SP) were used as positive control. Western blot was employed to detected p53 and p38 as well as JNK expressions and the activation and translocation of Bax and cytochrome C. Flow cytometer (FCM) was used to detect the mitochondrial membrane potential and cell apoptosis. Results. After separation and culture, 95% of cells showed positive cTnI expression, which indicated that mouse primary cardiomyocytes were successfully identified in our research. DOX activated p53 and MAPK signal pathways in a time-dependent manner, which were inactivated by being cotreated with SYKT, PFT-α, or SB, respectively. DOX significantly decreased Bax and increased cytochrome c expressions in the cytoplasm, whereas Bax was upregulated and cytochrome c was downregulated in the mitochondria, which were reversed by SYKT treatment. Besides, DOX reduced mitochondria membrane potential (MMP) in cardiomyocytes compared to the control group; SYKT recovered its MMP and attenuated DOX-induced cardiomyocyte injury. Of note, DOX increased the expression levels of cleaved caspase-3 as well as poly ADP-ribose polymerase (PARP) and promoted cell apoptosis, which were also reversed by SYKT treatment. Discussion and Conclusions. Our results indicated that SYKT alleviated DOX-induced cardiotoxicity by inhibiting p53 and MAPK signal pathways' activation-mediated apoptosis, and it might serve as a potential therapeutic agent for DOX-induced cardiotoxicity.

Antidiabetic adiponectin receptor agonist AdipoRon suppresses tumour growth of pancreatic cancer by inducing RIPK1/ERK-dependent necroptosis

The association between lower circulating adiponectin (APN) levels and the development of pancreatic cancer has been reported. However, the effect of APN on the growth and survival of pancreatic cancer cells remains elusive. Here, we investigate the effects of the anti-diabetic APN receptor (AdipoR) agonist AdipoRon and APN on human pancreatic cancer cells. We found that AdipoRon, but not APN, induces MIAPaCa-2 cell death, mainly through necroptosis. Mechanistically, although both AdipoRon and APN activate AMPK and p38 MAPK in an AdipoR-dependent manner that elicits survival signals, only AdipoRon induces rapid mitochondrial dysfunction through mitochondrial Ca²⁺ overload, followed by superoxide production via RIPK1 and ERK1/2 activation. Oral administration of AdipoRon suppresses MIAPaCa-2 tumour growth without severe adverse effects and kills cancer cells isolated from patients with pancreatic cancer. Thus, AdipoRon could be a therapeutic agent against pancreatic cancer as well as diabetes.

Rottlerin promotes autophagy and apoptosis in gastric cancer cell lines

It is widely accepted that apoptosis is closely associated with cancer cell death. However, whether autophagy induces tumor cell death has not been fully elucidated. Various studies have discussed the antitumor properties of rottlerin in human malignancies. The current study aimed to investigate the effects of rottlerin, a natural product isolated from the kamala tree (Mallotus philipensis), on growth inhibition and autophagy in gastric cancer (GC) cell lines in vitro. The results of the present study demonstrated that rottlerin suppressed cell growth, induced autophagy and apoptosis, and reduced migration and invasion in the SGC-7901 and MGC-803 GC cell lines. Furthermore, rottlerin led to microtubule-associated protein 1 light chain 3β-II augmentation and the enrichment of autophagosomes. In addition, the protein expression levels of mechanistic target of rapamycin kinase and S-phase kinase-associated protein 2 were downregulated in GC cells following rottlerin treatment, which is associated with autophagy. The protein levels of caspase-3, cleaved-caspase-3, total poly (ADP-ribose) polymerase (PARP) and cleaved-PARP exhibited no marked alterations in the GC cells following rottlerin treatment, indicating that caspases were likely not involved in rottlerin-induced GC apoptosis. In summary, the results of the present study indicate that rottlerin may inhibit invasion and promote apoptosis in GC cells, which may be mediated by the activation of autophagy. Therefore, rottlerin may be of value in the treatment of GC.

Cell-penetrating peptide conjugates of gambogic acid enhance the antitumor effect on human bladder cancer EJ cells through ROS-mediated apoptosis

Background

Gambogic acid (GA) is the main active ingredient of resin gamboges and possesses anti-cancer activity toward various human cancer cells. However, clinical application of GA has been limited by its poor aqueous solubility and dose-limiting toxicities. Cell-penetrating peptides (CPPs) are widely used to deliver anti-cancer drugs into cancer cells and to enhance the water solubility of drugs.

Purpose

The object of this study was to synthesize peptide-drug conjugates in which the cell-penetrating peptide TAT (trans-activator of transcription) was conjugated to GA and evaluated the anti-cancer activity of this GA-CPP conjugate (GA-TAT) in EJ bladder cancer cells.

Methods

GA is built onto the TAT, and the GA-TAT conjugates are cleaved from the solid support and purified via HPLC. The equilibrium solubility of GA-TAT was measured using the shake-flask method. The effects of GA-TAT on EJ cell viability and proliferation were determined by MTT assay, Edu assay and colony formation assay, respectively. After treated with 1.0 μM GA-TAT for 24 h, the apoptosis rate of EJ cells were detected by Acridine orange/ethidium bromide (AO/EB) assay and flow cytometry assay. The proteins of caspase-3 (processing), caspase-9 (processing), Bcl-2 and Bax were analyzed by Western blotting, and the intracellular reactive oxygen species (ROS) production was evaluated by a reactive oxygen species assay.

Results

In contrast to free GA, the solubility of GA-TAT in water was significantly improved. Meanwhile, GA-TAT significantly increased EJ cellular uptake, toxicity and apoptosis. Mechanistic analysis revealed that GA-TAT enhanced the anti-cancer effect of GA against EJ cells through ROS-mediated apoptosis. The results were demonstrated that GA-TAT increased the ROS level in EJ cells, and N-acetyl-L-cysteine (NAC; a well-known ROS scavenger) inhibited GA-TAT-induced ROS generation and apoptosis. Additionally, GA-TAT activated caspase-3 and caspase-9 and down-regulated the Bcl-2/Bax ratio, but these effects were largely rescued by NAC.

Conclusion

GA-TAT has outstanding potential for promoting tumor apoptosis and exhibits promise for use in bladder cancer therapy.

Downregulation of SKP2 in Papillary Thyroid Cancer Acts Synergistically With TRAIL on Inducing Apoptosis via ROS

CONTEXT AND OBJECTIVE

S-phase kinase protein 2 (SKP2) is an F-box protein with proteasomal properties and has been found to be overexpressed in a variety of cancers. However, its role in papillary thyroid cancer (PTC) has not been fully elucidated.

EXPERIMENTAL DESIGN

SKP2 expression was assessed by immunohistochemistry in a tissue microarray format on a cohort of >1000 PTC samples. In vitro and in vivo studies were performed using proteasome inhibitor bortezomib and proapoptopic death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) either alone or in combination on PTC cell lines.

RESULTS

SKP2 was overexpressed in 45.5% of PTC cases and was significantly associated with extrathyroidal extension (P = 0.0451), distant metastasis (P = 0.0435), and tall cell variant (P = 0.0271). SKP2 overexpression was also directly associated with X-linked inhibitor of apoptosis protein overexpression (P < 0.0001) and Bcl-xL overexpression (P = 0.0005) and inversely associated with death receptor 5 (P < 0.0001). The cotreatment of bortezomib and TRAIL synergistically induced apoptosis via mitochondrial apoptotic pathway in PTC cell lines. Furthermore, bortezomib and TRAIL synergistically induced reactive oxygen species (ROS) generation and caused death receptor 5 upregulation through activation of the extracellular signal-regulated kinase-C/EBP homologous protein signaling cascade. Finally, bortezomib treatment augmented the TRAIL-mediated anticancer effect on PTC xenograft tumor growth in nude mice.

CONCLUSION

These data suggest that SKP2 is a potential therapeutic target in PTC and that a combination of bortezomib and TRAIL might be a viable therapeutic option for the treatment of patients with aggressive PTC.