TPEN induces apoptosis independently of zinc chelator activity in a model of acute lymphoblastic leukemia and ex vivo acute leukemia cells through oxidative stress and mitochondria caspase-3- and AIF-dependent pathways

Zn2+ triazamacrocyclic chelators with methylpyridine pendant arms for B-cell apoptosis: a structure-activity study

Three macrocyclic tacn (1,4,7-triazacyclononane) derivatives containing one, two and three 2-methylpyridine pendant arms (no1py, no2py and no3py), compared to the linear diamine analogue tpen (N,N,N',N'-tetrakis(2-methylpyridinyl)-ethylenediamine) known for its capacity to induce cell apoptosis by Zn2+ chelation and/or ROS production, have shown cytotoxic activity on the Daudi B-cell line and CLL (chronic lymphoid leukemia) primary B cell model. These properties have been evidenced using an Incucyte® Live-Cell Analysis System. Evaluation of caspase 3/7 activation by incubation with the four studied chelators has exhibited caspase-dependent apoptotic death. Investigation of the chelator action mechanism has shown no ROS (reactive oxygen species) production for the macrocyclic chelators no1py, no2py and no3py, unlike the linear counterpart tpen for which ROS production was revealed. A significant inhibition effect of macrocyclic chelator cytotoxicity has been established by extracellular addition of cationic salts (Zn2+ and Cu2+) and the Zinquin emission fluorescence method has evidenced intracellular labile zinc chelation for no2py and no3py, while no1py acts differently. The acid-base properties of the chelators and their Zn2+ complexation constants have been obtained, discussed and correlated with the demonstrated biological properties.

Yanghe decoction alleviates osteoarthritis by AMPK-SIRT3 positive feedback loop-mediated mitochondrial autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Yanghe Decoction(YHD) is a traditional Chinese medicine compound known for its efficacy in treating osteoarthritis (OA).

AIM OF THE STUDY

We aimed to explore the underlying mechanisms of YHD in relation to OA.

MATERIALS AND METHODS

UHPLC-MS technology was used to identify the material basis of YHD. In vivo, OA rat model was induced by the modified Hulth method and then treated with YHD at three different doses (0.625, 1.3 and 2.6 g/kg/d). In vitro,YHD-Contained serum was prepared and administrated into rat chondrocytes, followed by simulation of Lipopolysaccharide(LPS). The protective mechanism was determined by observation of morphology, Flow cytometry and Protein level detection.

RESULTS

In vivo, YHD reduced chondrocyte apoptosis and joint inflammation while promoting mitophagy. It also elevated the protein levels of p-AMPK, SIRT3, PINK1, Parkin, and LC3II/I. In vitro, YHD-Contained Serum reduced chondrocyte apoptosis, decreased mitochondrial ROS, enhanced mitochondrial membrane potential, and upregulated the protein expressions of p-AMPK, SIRT3, PINK1, Parkin, and LC3II/I.

CONCLUSION

Through this study, we demonstrated YHD protect chondrocytes against apoptosis, and its underlying mechanisms may involve the regulation of AMPK-SIRT3 positive feedback loop and activation of PINK1/Parkin mediated mitophagy.

Polyimidazole ligands: Copper(II) complexes and antiproliferative activity in cancer cells

The design of novel chelators for therapeutic applications has been the subject of extensive research to address various diseases. Many chelators can manipulate the levels of metal ions within cells and effectively modulate the metal excess. In some cases, chelators show significant toxicity to cells. We investigated polyimidazole ligands by potentiometry and UV-Vis spectroscopy for their ability to form copper(II) complexes. We also compared the antiproliferative activity of the polyimidazole ligands and their copper(II) complexes with polypyridine ligands in CaCo-2 (colorectal adenocarcinoma), SH-SY5Y (neuroblastoma) and K562 (chronic myelogenous leukemia) cells and normal HaCaT (keratinocyte) cells. Polyimidazole ligands are less cytotoxic than their analogous polypyridine ligands. All polyimidazole ligands, except the tetraimidazole ligand for K562 cells, did not show any significant effect on the viability of cancer and normal cells. In contrast, the cytotoxic activity of polypiridine ligands was also observed in normal cells with IC50 values similar to those of cancer cells. Tetraimidazole ligand, the only ligand active on the leukemic K562 cell line, induced caspase-dependent apoptosis and increased intracellular reactive oxygen species production with mitochondrial damage. The low cytotoxicity of the polyimidazole ligands, even if it limits their use as anticancer agents, could make them useful in other medical applications, such as in the treatment of metal overload, microbial infections, inflammation or neurodegenerative disorders.

Evaluating the therapeutic potential of amygdalin: Cytotoxic and antimicrobial properties

Leukemia is an incurable disease; it exhibits strong resistance to chemotherapy and other therapies, and it represents the most common childhood cancer and mortality. The cytotoxic of amygdalin (AMG) against the cell line of human monocytic leukemia (THP-1) was recorded, before determining other pharmacological effects. The cells were exposed to AMG for 24 hr at 37°C at different concentrations, the cytotoxic effect was determined via the MTT assay. The cells and the supernatant were collected for analyzing the oxidant/antioxidant status, apoptotic markers, and anti-microbial activity. Results showed a marked anti-proliferative cytotoxic effect of AMG which is concentration and time-dependent, the lipid peroxidation content was significantly decreased while the total thiol was increased in the treated cell line, significant up-regulation of Caspase-3 (Cas-3) and Bcl-2-associated X protein (BAX) and down-regulation of B-cell lymphoma 2 (Bcl-2). Furthermore, The bacterial activity was detected via Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Disc Diffusion assays, while the antifungal evaluation was done by the Minimum Fungicidal Concentration (MFC). Antimicrobial experiments revealed that AMG exerted potent, broad-spectrum antimicrobial effects toward a diversity of dangerously infecting pathogens. In conclusion; the prevailing research suggests that AMG is an effective anticarcinogenic and antimicrobial substance. The utilization of AMG subsequently in masks or wound dressings to prevent bacterial & fungal infections, including mucormycosis following COVID-19, as well as infections caused by penicillium and aspergillus, is a highly effective strategy in combating resistant microorganisms.

Structurally diverse zinc(II) complexes containing tripodal tetradentate phenoxido-amines with promising antiproliferative effects

Structurally diverse zinc(II) complexes with tripodal tetradentate phenolic-amines of variable substituents in the phenol and amine moieties were synthesized and thoroughly characterized. The two dinuclear [Zn2(L1)2](ClO4)2·MeOH (1), [Zn2(L2)2](ClO4)2 (2), and four mononuclear [Zn(L3)(H2O)]·MeOH (3), [Zn(L4)] (4), [Zn(L5)] (5) and [Zn(L6)] (6) complexes revealed distorted octahedral, trigonal-bipyramidal or tetrahedral geometries. The free HL1 and H2L3-6 ligands, and complexes 1-6 were evaluated for in vitro cytotoxicity against human cancer cell lines (A2780, A2780R, PC-3 and 22Rv1) and normal healthy MRC-5 cells. Overall results revealed high-to-moderate cytotoxicity (with the best IC50 values for complex 6 ranging from 2.4 to 4.5 μM), which is however, significantly higher than that of the reference drug cisplatin. The moderately active complexes 1-4 showed considerable selectivity on A2780 cells (IC50 ≈ 16.3-19.5 μM) over MRC-5 ones (with IC50 >50 μM for 1, 2 and 4, and with IC50 >25 μM for 3). The complexes 1, 2, and 6 and the ligand H2L6 were chosen for subsequent deeper biological evaluations. Their time-resolved cellular uptake and other cellular effects in A2780 cells were studied, such as cell cycle profile, intracellular ROS production, induction of apoptosis and activation of caspases 3/7. Complexes 1 and 2 caused significant G0/G1 cell cycle arrest in A2780 cells and antioxidant effects at normal conditions. They showed only limited effects on cellular processes connected with cytotoxicity, i.e. induction of apoptosis, depletion of mitochondrial membrane potential, and autophagy. These findings can be at least partly attributed to the low ability of the complexes to enter the A2780 cells and the depression of metabolic activity of the target cancer cells.

PPARγ regulates osteoarthritis chondrocytes apoptosis through caspase-3 dependent mitochondrial pathway

Osteoarthritis (OA) is the most prevalent form of arthritis, characterized by a complex pathogenesis. One of the key factors contributing to its development is the apoptosis of chondrocytes triggered by oxidative stress. Involvement of peroxisome proliferator-activated receptor gamma (PPARγ) has been reported in the regulation of oxidative stress. However, there remains unclear mechanisms that through which PPARγ influences the pathogenesis of OA. The present study aims to delve into the role of PPARγ in chondrocytes apoptosis induced by oxidative stress in the context of OA. Primary human chondrocytes, both relatively normal and OA, were isolated and cultured for the following study. Various assessments were performed, including measurements of cell proliferation, viability and cytotoxicity. Additionally, we examined cell apoptosis, levels of reactive oxygen species (ROS), nitric oxide (NO), mitochondrial membrane potential (MMP) and cytochrome C release. We also evaluated the expression of related genes and proteins, such as collagen type II (Col2a1), aggrecan, inducible nitric oxide synthase (iNOS), caspase-9, caspase-3 and PPARγ. Compared with relatively normal cartilage, the expression of PPARγ in OA cartilage was down-regulated. The proliferation of OA chondrocytes decreased, accompanied by an increase in the apoptosis rate. Down-regulation of PPARγ expression in OA chondrocytes coincided with an up-regulation of iNOS expression, leading to increased secretion of NO, endogenous ROS production, and decrease of MMP levels. Furthermore, we observed the release of cytochrome C, elevated caspase-9 and caspase-3 activities, and reduction of the components of extracellular matrix (ECM) Col2a1 and aggrecan. Accordingly, utilization of GW1929 (PPARγ Agonists) or Z-DEVD-FMK (caspase-3 inhibitor) can protect chondrocytes from mitochondrial-related apoptosis and alleviate the progression of OA. During the progression of OA, excessive oxidative stress in chondrocytes leads to apoptosis and ECM degradation. Activation of PPARγ can postpone OA by down-regulating caspase-3-dependent mitochondrial apoptosis pathway.

Zn2+ is essential for Ca2+ oscillations in mouse eggs

Changes in the intracellular concentration of free calcium (Ca2+) underpin egg activation and initiation of development in animals and plants. In mammals, the Ca2+ release is periodical, known as Ca2+ oscillations, and mediated by the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1). Another divalent cation, zinc (Zn2+), increases exponentially during oocyte maturation and is vital for meiotic transitions, arrests, and polyspermy prevention. It is unknown if these pivotal cations interplay during fertilization. Here, using mouse eggs, we showed that basal concentrations of labile Zn2+ are indispensable for sperm-initiated Ca2+ oscillations because Zn2+-deficient conditions induced by cell-permeable chelators abrogated Ca2+ responses evoked by fertilization and other physiological and pharmacological agonists. We also found that chemically or genetically generated eggs with lower levels of labile Zn2+ displayed reduced IP3R1 sensitivity and diminished ER Ca2+ leak despite the stable content of the stores and IP3R1 mass. Resupplying Zn2+ restarted Ca2+ oscillations, but excessive Zn2+ prevented and terminated them, hindering IP3R1 responsiveness. The findings suggest that a window of Zn2+ concentrations is required for Ca2+ responses and IP3R1 function in eggs, ensuring optimal response to fertilization and egg activation.

Baicalin inhibits apoptosis and enhances chondrocyte proliferation in thiram-induced tibial dyschondroplasia in chickens by regulating Bcl-2/Caspase-9 and Sox-9/Collagen-II expressions

Avian tibial dyschondroplasia (TD) is a skeletal disease affecting fast growing chickens, resulting in non-mineralized avascular cartilage. This metabolic disorder is characterized by lameness and reduced growth performance causing economic losses. The aim of this study was to investigate the protective effects of baicalin against TD caused by thiram exposure. A total of two hundred and forty (n = 240) one day-old broiler chickens were uniformly and randomly allocated into three different groups (n = 80) viz. control, TD, and baicalin groups. All chickens received standard feed, however, to induce TD, the TD and baicalin groups received thiram (tetramethylthiuram disulfide) at a rate of 50 mg/kg feed from days 4-7. The thiram induction in TD and baicalin groups resulted in lameness, high mortality, and enlarged growth-plate, poor production performance, reduction in ALP, GSH-Px, SOD, and T-AOC levels, and increased AST and ALT, and MDA levels. Furthermore, histopathological results showed less vascularization, and mRNA and protein expression levels of Sox-9, Col-II, and Bcl-2 showed significant downward trend, while caspase-9 displayed significant up-regulation in TD-affected chickens. After the TD induction, the baicalin group was orally administered with baicalin at a rate of 200 mg/kg from days 8-18. Baicalin administration increased the vascularization, and chondrocytes with intact nuclei, alleviated lameness, decreased GP size, increased productive capacity, and restored the liver antioxidant enzymes and serum biochemical levels. Furthermore, baicalin significantly up-regulated the gene and protein expressions of Sox-9, Col-II, and Bcl-2, and significantly down-regulated the expression of caspase-9 (p < 0.05). Therefore, the obtained results suggest that baicalin could be a possible choice in thiram toxicity alleviation by regulating apoptosis and chondrocyte proliferation in thiram-induced tibial dyschondroplasia.

Zn2+ is Essential for Ca2+ Oscillations in Mouse Eggs

Changes in the intracellular concentration of free calcium (Ca2+) underpin egg activation and initiation of development in animals and plants. In mammals, the Ca2+ release is periodical, known as Ca2+ oscillations, and mediated by the type 1 inositol 1,4,5-trisphosphate receptor (IP3R1). Another divalent cation, zinc (Zn2+), increases exponentially during oocyte maturation and is vital for meiotic transitions, arrests, and polyspermy prevention. It is unknown if these pivotal cations interplay during fertilization. Here, using mouse eggs, we showed that basal concentrations of labile Zn2+ are indispensable for sperm-initiated Ca2+ oscillations because Zn2+-deficient conditions induced by cell-permeable chelators abrogated Ca2+ responses evoked by fertilization and other physiological and pharmacological agonists. We also found that chemically- or genetically generated eggs with lower levels of labile Zn2+ displayed reduced IP3R1 sensitivity and diminished ER Ca2+ leak despite the stable content of the stores and IP3R1 mass. Resupplying Zn2+ restarted Ca2+ oscillations, but excessive Zn2+ prevented and terminated them, hindering IP3R1 responsiveness. The findings suggest that a window of Zn2+ concentrations is required for Ca2+ responses and IP3R1 function in eggs, ensuring optimal response to fertilization and egg activation.

TPEN/TPGS (T2) combo dramatically reduces Philadelphia chromosome-positive pro-lymphoblastic B leukemia in BALB/c mice

Acute lymphoblastic leukemia (ALL) is hematological neoplasia that affects human beings from early life to adulthood. Although ALL treatment has been effective, an important percentage of ALL patients are resilient to treatment. Therefore, there is an urgent need for testing a new combination of compounds for the treatment of this disease. Recently, combined TPEN and TPGS (T2 combo) have shown selective cytotoxic effects in vitro leukemia cells such as Jurkat, K562, and Ba/F3 cells. In this study, we aimed to test the effect of combined TPEN and TPGS agents (T2 combo) at a fixed dose (TPEN 5 mg/kg: TPGS 100 mg/kg) on leukemic Ba/F3-BCR-ABL P210 BALB-c mice model. We found that 4 successive 2-day apart intravenous injections of T2 combo showed a statistically significant reduction of Ba/F3 BCR-ABL leukemia cells (- 69%) in leukemia BALB/c mice (n = 6) compared to untreated leukemia group (n = 6). Moreover, the T2 combo was innocuous to non-leukemia BALB/c mice (n = 3) compared to untreated non-leukemia mice (control, n = 3). After treatments (day 42), all mice were left to rest until day 50. Outstandingly, the leukemia BALB/c mice treated with the T2 combo showed a lower percentage of Ba/F3-BCR-ABL P210 cells (- 84%) than untreated leukemia BALB/c mice. Furthermore, treatment of leukemia and non-leukemia mice with T2 combo showed no significant tissue alteration/damage according to the histopathological analysis of brain, heart, liver, kidney, and spleen samples; however, T2 combo significantly reduced the number of leukocytes in the bone marrow of treated leukemia mice. We conclude that the T2 combo specifically affects leukemia cells but no other tissue/organs. Therefore, we anticipate that the T2 combo might be a potential pro-oxidant combination for the treatment of leukemia patients.

Comparison of Different Clinical Chemotherapeutical Agents’ Toxicity and Cell Response on Mesenchymal Stem Cells and Cancer Cells

Mesenchymal stem cells (MSCs) or fibroblasts are one of the most abundant cell types in the tumor microenvironment (TME) exerting various anti- and pro-apoptotic effects during tumorigenesis, invasion, and drug treatment. Despite the recently discovered importance of MSCs in tumor progression and therapy, the response of these cells to chemotherapeutics compared to cancer cells is rarely investigated. A widely accepted view is that these naive MSCs have higher drug tolerance than cancer cells due to a significantly lower proliferation rate. Here, we examine the differences and similarities in the sensitivity of MSCs and cancer cells to nine diverse chemotherapy agents and show that, although MSCs have a slower cell cycle, these cells are still sensitive to various drugs. Surprisingly, MSCs showed similar sensitivity to a panel of compounds, however, suffered fewer DNA double-stranded breaks, did not enter into a senescent state, and was virtually incapable of apoptosis. Our results suggest that MSCs and cancer cells have different cell fates after drug treatment, and this could influence therapy outcome. These findings could help design drug combinations targeting both MSCs and cancer cells in the TME.

Induced Zinc Loss Produces Heterogenous Biological Responses in Melanoma Cells

Zinc levels in serum and/or tissue are reported to be altered in melanoma with unknown effects on melanoma development and biology. The purpose of this study was to examine the effects of acute chelation of free intracellular zinc pools in melanoma cell lines Bowes and A375, as well as selected melanoma tissue explants with high or low intracellular free zinc. Zinc chelating agent TPEN at the concentration of 25 µM was employed during 48 h, which significantly reduced intracellular free zinc while decreasing melanoma cell proliferation, inducing G1/S arrest and cell damage leading to mitochondrial, caspase-dependent apoptosis. Chelation of free zinc was also associated with increased generation of superoxide in cell lines but not marked lysosomal membrane damage. Conversely, melanoma explant cultures mostly displayed time-dependent loss of lysosomal membrane integrity in the presence of slowly growing superoxide levels. Loss of free zinc-dependent p53 activity was similarly disparate in individual melanoma models. Surviving melanoma cells were arrested in the cell cycle, and varying proportions of them exhibited features characteristic of premature senescence, which increased in time despite zinc reloading. The present results show that melanoma cells with varying free zinc levels respond to its acute loss in a number of individual ways, reflecting activated mechanisms including oxidative stress, lysosomal damage, and p53 activity leading to heterogenous outcomes including cell death, transient, and/or permanent cell cycle arrest and premature senescence.

New Triazacycloalkane Derivatives as Cytotoxic Agents for CLL Treatment: From Proof of Concept to the Targeting Biomolecule

The 1,4,7-tris-(2-pyridinylmethyl)-1,4,7-triazacyclononane ligand (no3py) and its bifunctional analogue no3pyCOOK were synthesized to investigate their action toward zinc(II) depletion related to the apoptosis phenomenon in chronic lymphocytic leukemia (CLL) cells. no3py was used as the "free" ligand, while its "graftable" derivative was conjugated on a newly synthesized bifunctional sialoglycan, 6'-SL-NH₂, selected to specifically bind CD22 biomarker expressed on the B-CLL cell surface. Both compounds were produced with good yields thanks to a Sonogashira coupling reaction and an orthoester function, respectively, for the chelator and the targeting moiety. The newly reported bioconjugate 6'-SL-no3py was then obtained through a peptidic coupling reaction. Biological in vitro studies of no3py and 6'-SL-no3py consisting of real-time detection of cell health (cytotoxicity and proliferation) and caspases 3/7 activation (crucial enzymes whose activation triggers cell death signaling pathways) have been investigated. First, Ramos, Daudi, and Raji B-cell lines, which present different sensitivity to zinc(II) content variation, were incubated with no3py and 6'-SL-no3py. Then, a videomicroscope allowed the real-time monitoring of the morphological changes leading to cell death from the detection of the cytotoxicity, the antiproliferative effect, and the caspasic activity. In terms of mechanism, the Zn²⁺ chelator cytotoxic effect of no3py has been evidenced by a culture medium ion supplementation study and by the decrease of intracellular fluorescence of Zn-specific fluorophore zinquin in the presence of no3py and 6'-SL-no3py chelators. Finally, flow cytometry analysis with classical Annexin V staining was conducted to detect no3py- and 6'-SL-no3py-induced apoptotic cell death in B-CLL cells. Time-course analysis, using the Incucyte Live-Cell Analysis System, demonstrated that no3py induced cell death in a time- and dose-dependent manner with variability across cell lines. 6'-SL-no3py exhibited the same dose-dependent trend as no3py, showing the efficiency of the targeting moiety. In both cases, the chelators depicted proliferation curves that were inversely correlated with kinetic death. Morphological changes specific to apoptosis and caspase 3/7 activation were observed for the three cell lines treated with no3py and 6'-SL-no3py, highlighting their role as apoptotic agents. A higher concentration of 6'-SL-no3py is needed to reach 50% of the B-CLL mortality, confirming a targeting of the chelator to the cell membrane. Overall, our results proved that the biological properties of the triazamacrocyclic chelator still remain even after addition of the targeting moiety. The free chelator as well as the bioconjugate constitute promising cytotoxic agents for CLL therapy through apoptosis induction.

TPEN selectively eliminates lymphoblastic B cells from bone marrow pediatric acute lymphoblastic leukemia patients

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic disorder characterized by the abnormal proliferation and accumulation of immature B-lymphoblasts arrested at various stages of differentiation. Despite advances in treatment, a significant percentage of pediatric patients with precursor B-ALL still relapse. Therefore, alternative therapies are needed to improve the cure rates for pediatric patients. TPEN (N, N, N', N'-tetrakis(2-pyridylmethyl)-ethylenediamine) is a pro-oxidant agent capable of selectively inducing apoptosis in leukemia cell lines. Consequently, it has been suggested that TPEN could be a potential agent for oxidative therapy. However, it is not yet known whether TPEN can selectively destroy leukemia cells in a more disease-like model, for example, the bloodstream and bone marrow (BM), ex vivo. This investigation is an extension of a previous study that dealt with the effect of TPEN on ex vivo isolated/purified refractory B-ALL cells. Here, we evaluated the effect of TPEN on whole BM from nonleukemic patients (control) or pediatric patients diagnosed with de novo B-ALL or refractory B-ALL cells by analyzing the hematopoietic cell lineage marker CD34/CD19. Although TPEN was innocuous to nonleukemic BM (n = 3), we found that TPEN significantly induced apoptosis in de novo (n = 5) and refractory B-ALL (n = 6) leukemic cell populations. Moreover, TPEN significantly increased the counts of cells positive for the oxidation of the stress sensor protein DJ-1, a sign of the formation of H₂O₂, and significantly increased the counts of cells positive for the pro-apoptotic proteins TP53, PUMA, and CASPASE-3 (CASP-3), indicative of apoptosis, in B-ALL cells. We demonstrate that TPEN selectively eliminates B-ALL cells (CD34 + /CD19 +) but no other cell populations in BM (CD34 + /CD19-; CD34-/CD19 + ; CD34-/CD19-) independent of age, diagnosis status (de novo or refractory), sex, karyotype, or immunophenotype. Understanding TPEN-induced cell death in leukemia cells provides insight into more effective therapeutic oxidation-inducing anticancer agents.

Combinational treatment of TPEN and TPGS induces apoptosis in acute lymphoblastic and chronic myeloid leukemia cells in vitro and ex vivo

TPEN and TPGS have recently shown selective cytotoxic effects in vitro and ex vivo leukemia cells. In this study, we aimed to test the synergistic effect of combined TPEN and TPGS agents (thereafter, T2 combo) on Jurkat (clone-E61), K562, Ba/F3, and non-leukemia peripheral blood lymphocytes (PBL). The ED50 doses (i.e., TPEN ED50: 3.2 μM and TPGS ED50: 34 μM, potency ratio R = 10.62 = TPGS (ED50)/TPEN (ED50)) were identified as dose-effect curve (%DNA fragmentation (sub-G₁ phase) versus agent concentration). The most effective synergistic doses were determined according to isobole analysis. The apoptotic and oxidative stress effects of combined doses (TPEN 0.1, 0.5, 1 μM) and TPGS (5, 10, 20 μM)) were evaluated by DNA fragmentation (sub-G₁ phase), mitochondrial membrane potential, oxidation of stress sensor protein DJ-1, and activation of executer protein CASPASE-3. They testified to the synergistic effect of the T2 combo (e.g., TPEN 1: TPGS 20, combination index (CI) 0.90 < 1; 1/3.2+ 20/34, > 90% induced apoptosis) in all 3 cell lines. As proof of principle, we challenged complete bone marrow (n = 5) or isolated cells from bone marrow (n = 3) samples from acute pediatric acute B-cell patients and found that T2 combo (1:20; 10:200) dramatically reduced (- 50%) the CD34+/CD19+cell population and increased significantly CD19+/CASP-3+ positive B-ALL cells up to 960%. The T2 combo neither induced DNA fragmentation, altered ΔΨm, nor induced oxidation of stress sensor protein DJ-1, nor activated CASP-3 in PBL cells. We conclude that by using different combinations of TPEN and TPGS, a more efficient treatment strategy can be developed for leukemia patients.

Adherence Enables Neisseria gonorrhoeae to Overcome Zinc Limitation Imposed by Nutritional Immunity Proteins

Neisseria gonorrhoeae (Gc) must overcome the limitation of metals such as zinc to colonize mucosal surfaces in its obligate human host. While the zinc-binding nutritional immunity proteins calprotectin (S100A8/A9) and psoriasin (S100A7) are abundant in human cervicovaginal lavage fluid, Gc possesses TonB-dependent transporters TdfH and TdfJ that bind and extract zinc from the human version of these proteins, respectively. Here we investigated the contribution of zinc acquisition to Gc infection of epithelial cells of the female genital tract. We found that TdfH and TdfJ were dispensable for survival of strain FA1090 Gc that was associated with Ect1 human immortalized epithelial cells, when zinc was limited by calprotectin and psoriasin. In contrast, suspension-grown bacteria declined in viability under the same conditions. Exposure to murine calprotectin, which Gc cannot use as a zinc source, similarly reduced survival of suspension-grown Gc, but not Ect1-associated Gc. We ruled out epithelial cells as a contributor to the enhanced growth of cell-associated Gc under zinc limitation. Instead, we found that attachment to glass was sufficient to enhance bacterial growth when zinc was sequestered. We compared the transcriptional profiles of WT Gc adherent to glass coverslips or in suspension, when zinc was sequestered with murine calprotectin or provided in excess, from which we identified open reading frames that were increased by zinc sequestration in adherent Gc. One of these, ZnuA, was necessary but not sufficient for survival of Gc under zinc-limiting conditions. These results show that adherence protects Gc from zinc-dependent growth restriction by host nutritional immunity proteins.

Zinc ions negatively regulate proapoptotic signaling in cells expressing oncogenic mutant Ras

Mutational activation of the Ras family of proto-oncogenes promotes cell survival and proliferation. Studies using cells cultured in vitro have shown that ectopic expression of constitutively active Ras suppresses apoptosis induced by serum deprivation. However, in some cellular contexts, constitutively active Ras exerts the opposite effects, including apoptosis of serum-starved embryonic fibroblasts. Such observations first came over two decades ago, but the molecular mechanisms by which mutant Ras increases the susceptibility of cells to serum deprivation leading to apoptosis are still not fully understood. To revisit this issue, I investigate the effects of serum depletion and mutant Ras expression on intracellular signaling and transcriptome of cells carrying an inducible allele of constitutively active mutant Hras (Hras^G12V). I identify zinc ions (Zn²⁺) as a serum factor that suppresses proapoptotic signaling in cells expressing Hras^G12V. Mechanistically, Hras^G12V expression along with Zn²⁺ deficiency activates c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), which are required for caspase-3 activation involved in the induction of cell death. Transcriptome analyses suggest that Hras^G12V induces the unfolded protein response (UPR). Further analyses of intracellular signaling biomolecules related to the UPR indicate that Hras^G12V activates inositol-requiring protein 1 (IRE1), which synergizes with Zn²⁺ deficiency to activate JNK and p38 MAPK signaling. These results provide insights into a role of Zn²⁺ that counteracts proapoptotic signaling activated by mutationally activated Ras.

Design of novel oocyte activation methods: The role of zinc

Oocyte activation occurs at the time of fertilization and is a series of cellular events initiated by intracellular Ca2+ increases. Consequently, oocytes are alleviated from their arrested state in meiotic metaphase II (MII), allowing for the completion of meiosis. Oocyte activation is also an essential step for somatic cell nuclear transfer (SCNT) and an important tool to overcome clinical infertility. Traditional artificial activation methods aim to mimic the intracellular Ca2+ changes which occur during fertilization. Recent studies emphasize the importance of cytoplasmic Zn2+ on oocyte maturation and the completion of meiosis, thus suggesting artificial oocyte activation approaches that are centered around the concentration of available Zn2+in oocytes. Depletion of intracellular Zn2+ in oocytes with heavy metal chelators leads to successful oocyte activation in the absence of cellular Ca2+ changes, indicating that successful oocyte activation does not always depends on intracellular Ca2+ increases. Current findings lead to new approaches to artificially activate mammalian oocytes by reducing available Zn2+ contents, and the approaches improve the outcome of oocyte activation when combined with existing Ca2+ based oocyte activation methods. Here, we review the important role of Ca2+ and Zn2+ in mammalian oocyte activation and development of novel oocyte activation approaches based on Zn2+ availability.

Reactive Oxygen Species in Acute Lymphoblastic Leukaemia: Reducing Radicals to Refine Responses

Acute lymphoblastic leukaemia (ALL) is the most common cancer diagnosed in children and adolescents. Approximately 70% of patients survive >5-years following diagnosis, however, for those that fail upfront therapies, survival is poor. Reactive oxygen species (ROS) are elevated in a range of cancers and are emerging as significant contributors to the leukaemogenesis of ALL. ROS modulate the function of signalling proteins through oxidation of cysteine residues, as well as promote genomic instability by damaging DNA, to promote chemotherapy resistance. Current therapeutic approaches exploit the pro-oxidant intracellular environment of malignant B and T lymphoblasts to cause irreversible DNA damage and cell death, however these strategies impact normal haematopoiesis and lead to long lasting side-effects. Therapies suppressing ROS production, especially those targeting ROS producing enzymes such as the NADPH oxidases (NOXs), are emerging alternatives to treat cancers and may be exploited to improve the ALL treatment. Here, we discuss the roles that ROS play in normal haematopoiesis and in ALL. We explore the molecular mechanisms underpinning overproduction of ROS in ALL, and their roles in disease progression and drug resistance. Finally, we examine strategies to target ROS production, with a specific focus on the NOX enzymes, to improve the treatment of ALL.

Polypyridine ligands as potential metallo-β-lactamase inhibitors

Bacteria have developed multiple resistance mechanisms against the most used antibiotics. In particular, zinc-dependent metallo-β-lactamase producing bacteria are a growing threat, and therapeutic options are limited. Zinc chelators have recently been investigated as metallo-β-lactamase inhibitors, as they are often able to restore carbapenem susceptibility. We synthesized polypyridyl ligands, N,N'-bis(2-pyridylmethyl)-ethylenediamine, N,N,N'-tris(2-pyridylmethyl)-ethylenediamine, N,N'-bis(2-pyridylmethyl)-ethylenediamine-N-acetic acid (N,N,N'-tris(2-pyridylmethyl)-ethylenediamine-N'-acetic acid, which can form zinc(II) complexes. We tested their ability to restore the antibiotic activity of meropenem against three clinical strains isolated from blood and metallo-β-lactamase producers (Klebsiella pneumoniae, Enterobacter cloacae, and Stenotrophomonas maltophilia). We functionalized N,N,N'-tris(2-pyridylmethyl)-ethylenediamine with D-alanyl-D-alanyl-D-alanine methyl ester with the aim to increase bacterial uptake. We observed synergistic activity of four polypyridyl ligands with meropenem against all tested isolates, while the combination N,N'-bis(2-pyridylmethyl)-ethylenediamine and meropenem was synergistic only against New Delhi and Verona integron-encoded metallo-β-lactamase-producing bacteria. All synergistic interactions restored the antimicrobial activity of meropenem, providing a significant decrease of minimal inhibitory concentration value (by 8- to 128-fold). We also studied toxicity of the ligands in two normal peripheral blood lymphocytes.

Predication of the underlying mechanism of Bushenhuoxue formula acting on knee osteoarthritis via network pharmacology-based analyses combined with experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Knee osteoarthritis (KOA) is the most common chronic joint disorder worldwide, which is also a principle consideration for disability. The Bushenhuoxue formula (BSHXF) is a traditional herbal formula which widely applied to the treatment of KOA. However, its pharmacological mechanisms of action have not been clarified.

AIMS OF THE STUDY

The study aimed to identify the potential targets and mechanisms of BSHXF in the treatment of KOA through pharmacology-based analyses and experimental validation.

MATERIALS AND METHODS

The TCMSP database was applied to obtain the chemical compounds and targets of BSHXF, while the protein targets in KOA were determined through GeneCards and OMIM databases. The herb-compound-target and protein-protein interaction (PPI) networks were constructed for topological analyses and hub-targets screening. GO and KEGG enrichment analyses were performed on these core nodes to identify the critical biological processes and signaling pathways. Then destabilization of medial meniscus (DMM)-induced C57BL/6J mice model was established to detect the level of apoptosis via TUNEL assessment, while the expressions of CASP3, CASP8 and CASP9 were determined by immunohistochemistry.

RESULTS

A total of 154 active compounds and 58 targets were predicted. DAVID, ClueGO and Metascape enrichment analyses all proved that BSHXF plays an essential role in regulating apoptosis. Moreover, 3 central nodes of BSHXF are recognized as the active factors involved in the main biological functions, suggesting a potential mechanism of BSHXF for KOA treatment. In vivo experiment revealed that BSHXF significantly inhibited apoptosis and down-regulated the expressions of CASP3, CASP8 and CASP9.

CONCLUSION

Based on network pharmacology and experimental validation, our study indicated that BSHXF exerted anti-apoptosis effect through inhibiting the expressions of CASP3, CASP8 and CASP9, which could be considered as an effective method for KOA treatment.

Zinc regulates primary ovarian tumor growth and metastasis through the epithelial to mesenchymal transition

BACKGROUND

The trace element zinc plays an indispensable role in human health and diseases including cancer due to its antioxidant properties. While zinc supplements have been used for cancer prevention, zinc is also a risk factor for cancer development. It is still unclear how zinc plays a role in ovarian cancer.

METHODS

To understand how zinc contributes to ovarian tumor growth and metastasis, we examined whether zinc contributes to tumor metastasis by regulating epithelial to mesenchymal transition (EMT) using ovarian cancer cells in vitro. Cell migration and invasion were examined using transwell plates and EMT markers were examined using Western blot. Primary ovarian tumor growth and metastasis were assessed using orthotopic ovarian cancer mouse models in vivo.

RESULTS

Zinc promoted EMT, while TPEN (N, N, N', N'-tetrakis-(2-pyridylmethyl)-ethylenediamine), a membrane-permeable selective zinc chelator, inhibited EMT in a dose dependent manner in ovarian cancer cells. Moreover, zinc promoted ovarian cancer cell migration and invasion, while TPEN inhibited cell migration and invasion. Zinc activated expression of the metal response transcriptional factor-1 (MTF-1), while TPEN inhibited MTF-1 expression in a dose dependent manner. Knockout of MTF-1 inhibited zinc-induced cell migration, invasion and augmented the inhibitory effect of TPEN on cell migration and invasion. Loss of MTF-1 attenuated zinc-induced ERK1/2 and AKT activation and augmented the effect of TPEN in attenuating the ERK1/2 and AKT pathways. TPEN effectively inhibited primary ovarian tumor growth and metastasis in an orthotopic ovarian cancer mouse model by suppressing EMT.

CONCLUSION

zinc contributes to ovarian tumor metastasis by promoting EMT through a MTF-1 dependent pathway. Zinc depletion by TPEN may be a novel approach for ovarian cancer therapy by inhibiting EMT and attenuating the ERK1/2 and AKT pathways.

Zinc Modulates Several Transcription-Factor Regulated Pathways in Mouse Skeletal Muscle Cells

Zinc is an essential metal ion involved in many biological processes. Studies have shown that zinc can activate several molecules in the insulin signalling pathway and the concomitant uptake of glucose in skeletal muscle cells. However, there is limited information on other potential pathways that zinc can activate in skeletal muscle. Accordingly, this study aimed to identify other zinc-activating pathways in skeletal muscle cells to further delineate the role of this metal ion in cellular processes. Mouse C2C12 skeletal muscle cells were treated with insulin (10 nM), zinc (20 µM), and the zinc chelator TPEN (various concentrations) over 60 min. Western blots were performed for the zinc-activation of pAkt, pErk, and pCreb. A Cignal 45-Reporter Array that targets 45 signalling pathways was utilised to test the ability of zinc to activate pathways that have not yet been described. Zinc and insulin activated pAkt over 60 min as expected. Moreover, the treatment of C2C12 skeletal muscle cells with TPEN reduced the ability of zinc to activate pAkt and pErk. Zinc also activated several associated novel transcription factor pathways including Nrf1/Nrf2, ATF6, CREB, EGR1, STAT1, AP-1, PPAR, and TCF/LEF, and pCREB protein over 120 min of zinc treatment. These studies have shown that zinc's activity extends beyond that of insulin signalling and plays a role in modulating novel transcription factor activated pathways. Further studies to determine the exact role of zinc in the activation of transcription factor pathways will provide novel insights into this metal ion actions.

TPEN exerts selective anti-leukemic efficacy in ex vivo drug-resistant childhood acute leukemia

Despite some advances in the treatment of acute lymphoblastic (ALL) and myeloid leukemia (AML) in recent years, there is still a prominent percentage of pediatric patients with a reduced overall prognosis. Therefore, other therapeutic approaches are needed to treat those patients. In the present study, we report that the metal chelator TPEN affected ΔΨ_m and DNA content in isolated CD34⁺ refractory cells from bone marrow ALL (n = 7; B-cell, n = 4; T-cell, n = 3) and AML (n = 3) pediatric patients. Furthermore, TPEN induced oxidation of hydrogen peroxide (H₂O₂) sensor protein DJ-1, induced up-regulation of BH3-only pro-apoptotic protein PUMA, transcription factor p53 and activated the executor protease CASPASE-3 as apoptosis markers, and reduced the reactivity of the cellular proliferating marker Ki-67 in all acute leukemic groups, and reduced the phosphorylation of c-ABL protein signal in an AML case. Remarkably, bone marrow cells from non-leukemic patients' cells (n = 2) displayed neither loss of ΔΨ_m nor loss of DNA content when exposed to TPEN. We conclude that TPEN selectively induces apoptosis in acute leukemic cells via reactive oxygen species (ROS) signaling mechanism. Understanding the pathways of TPEN-induced cell death may provide insight into more effective therapeutic ROS-inducing anticancer agents.

Single cell analysis reveals multiple requirements for zinc in the mammalian cell cycle

Zinc is widely recognized as essential for growth and proliferation, yet the mechanisms of how zinc deficiency arrests these processes remain enigmatic. Here we induce subtle zinc perturbations and track asynchronously cycling cells throughout division using fluorescent reporters, high throughput microscopy, and quantitative analysis. Zinc deficiency induces quiescence and resupply stimulates synchronized cell-cycle reentry. Monitoring cells before and after zinc deprivation we found the position of cells within the cell cycle determined whether they either went quiescent or entered another cell cycle but stalled in S-phase. Stalled cells exhibited prolonged S-phase, were defective in DNA synthesis and had increased DNA damage levels, suggesting a role for zinc in maintaining genome integrity. Finally, we demonstrate zinc deficiency-induced quiescence occurs independently of DNA-damage response pathways, and is distinct from mitogen removal and spontaneous quiescence. This suggests a novel pathway to quiescence and reveals essential micronutrients play a role in cell cycle regulation.

Upregulation of ZIP14 and Altered Zinc Homeostasis in Muscles in Pancreatic Cancer Cachexia

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer type in which the mortality rate approaches the incidence rate. More than 85% of PDAC patients experience a profound loss of muscle mass and function, known as cachexia. PDAC patients with this condition suffer from decreased tolerance to anti-cancer therapies and often succumb to premature death due to respiratory and cardiac muscle wasting. Yet, there are no approved therapies available to alleviate cachexia. We previously found that upregulation of the metal ion transporter, Zip14, and altered zinc homeostasis are critical mediators of cachexia in metastatic colon, lung, and breast cancer models. Here, we show that a similar mechanism is likely driving the development of cachexia in PDAC. In two independent experimental metastasis models generated from the murine PDAC cell lines, Pan02 and FC1242, we observed aberrant Zip14 expression and increased zinc ion levels in cachectic muscles. Moreover, in advanced PDAC patients, high levels of ZIP14 in muscles correlated with the presence of cachexia. These studies underscore the importance of altered ZIP14 function in PDAC-associated cachexia development and highlight a potential therapeutic opportunity for improving the quality of life and prolonging survival in PDAC patients.

TPEN Exerts Antitumor Efficacy in Murine Mammary Adenocarcinoma Through an H2O2 Signaling Mechanism Dependent on Caspase-3

BACKGROUND

Breast cancer is the second most common cancer worldwide. N, N, N', N'-Tetrakis (2-pyridylmethyl)-ethylenediamine (TPEN) is a lipid-soluble zinc metal chelator that induces apoptosis in cancer cells through oxidative stress (OS). However, the effectiveness and the mechanisms involved in TPENinduced cell death in mammary adenocarcinoma cells in vitro and in vivo are still unclear.

OBJECTIVE

This study aimed to evaluate the cytotoxic effect of TPEN in mouse embryonic fibroblasts (MEFs, as normal control cells) and mammary adenocarcinoma cancer cells (TS/A cells) in vitro and in a mammary tumor model in vivo.

METHODS

Cells were treated with TPEN (0-3 µM), and changes in nuclear chromatin and DNA, mitochondrial membrane potential (ΔΨm), and intracellular reactive oxygen species (ROS) levels were determined by both fluorescence microscopy and flow cytometry. Cell proliferation and the cell cycle were also analyzed. Cellular markers of apoptosis were evaluated by Western blot. Finally, the effect of TPEN in a mammary adenocarcinoma tumor model in vivo was determined by immunohistological analyses.

RESULTS

TPEN induced apoptosis in TS/A cells in a dose-dependent manner, increasing nuclear chromatin condensation, DNA fragmentation, cell cycle arrest and ΔΨm loss. Additionally, TPEN increased dichlorofluorescein fluorescence (DCF+) intensity, indicative of ROS production; increased DJ-1-Cys106-sulfonate expression, a marker of intracellular H2O2 stress; induced p53 and PUMA upregulation; and activated caspase-3. Moreover, TPEN induced mammary cancer cell elimination and tumor size reduction in vivo 48 h after treatment through an OS-induced apoptotic mechanism.

CONCLUSION

TPEN selectively induces apoptosis in TS/A cells through an H2O2-mediated signaling pathway. Our findings support the use of TPEN as a potential treatment for breast cancer.

Modification of cell vulnerability to oxidative stress by N-(3-oxododecanoyl)-L-homoserine-lactone, a quorum sensing molecule, in rat thymocytes

N-(3-oxododecanoyl)-l-homoserine-lactone (ODHL), a quorum sensing molecule, affects intracellular Zn²⁺ concentration ([Zn²⁺]i) and cellular levels of nonprotein thiols ([NPT]i) of rat thymic lymphocytes, both of which are assumed to affect cell vulnerability to oxidative stress. Therefore, it is interesting to examine the effects of ODHL on the cells under oxidative stress. ODHL augmented the cytotoxicity of H₂O₂, but not calcium ionophore A23187. ODHL potentiated the H₂O₂-induced elevation of [Zn²⁺]i, wherein, it greatly attenuated the H₂O₂-induced increase in intracellular Ca²⁺ concentration. ODHL did not affect [NPT]i in the presence of H₂O₂. Therefore, we conclude that the elevation of [Zn²⁺]i is involved in the ODHL-induced potentiation of H₂O₂ cytotoxicity. Our findings suggest that ODHL modifies cell vulnerability to oxidative stress in host cells.

PI3K/Akt and caspase pathways mediate oxidative stress-induced chondrocyte apoptosis

Chondrocyte apoptosis is closely related to the development and progression of osteoarthritis (OA); however, the underlying mechanisms remain enigmatic. Previous studies have confirmed that cell apoptosis is one of the main pathological alterations during oxidative stress, and chondrocyte apoptosis induced by oxidative stress plays an important role in the development of OA. Rat chondrocytes exposed to hydrogen peroxide (H2O2) were used as the experimental oxidative stress model. We assessed cell viability, cell apoptosis, levels of intracellular reactive oxygen species (ROS), nitric oxide (NO) production, gene relative expression level of inducible nitric oxide synthase (iNOS), and expressions of iNOS, PI3K, phospho-Akt, caspase-9, and caspase-3. With the rising of intracellular ROS and increasing iNOS synthesis, producing a large amount of NO in chondrocytes, H2O2 decreased the cell viability and induced cell apoptosis of chondrocytes. Furthermore, the levels of caspase-9 and caspase-3 protein expression were significantly elevated as well as the level of p-Akt protein expression when induced by oxidative stress. These findings suggest that oxidative stress-induced chondrocyte apoptosis occurred via activating both PI3K/Akt and caspase pathways in the early stage in these processes.

Vitamin E synthetic derivate-TPGS-selectively induces apoptosis in jurkat t cells via oxidative stress signaling pathways: implications for acute lymphoblastic leukemia

D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) is a water-soluble derivative of natural vitamin E commonly used as a drug delivery agent. Recently, TPGS alone has been reported to induce cell death in lung, breast and prostate cancer. However, the effect of TPGS on cancer cell viability remains unclear. Thus, this study was aimed to evaluate the cytotoxic effect of TPGS on human periphral blood lymphocytes (PBL) and on T cell acute lymphocytic leukemia (ALL) Jurkat clone E6-1 cells and its possible mechanism of action. PBL and Jurkat cells were treated with TPGS (10, 20, 40, 60, and 80 μM), and morphological changes in the cell nucleus, mitochondrial membrane potential (ΔΨm), and intracellular reactive oxygen species levels were determined by immune-fluorescence microscopy and flow cytometry. Cellular apoptosis markers were also evaluated by immunocytochemistry. In this study, TPGS induced apoptotic cell death in Jurkat cells, but not in PBL, in a dose-response manner with increasing nuclear DNA fragmentation, increasing cell cycle arrest, and decreasing ΔΨm. Additionally, TPGS increased dichlorofluorescein fluorescence intensity, indicative of H2O2 production, in a dose-independent fashion. TPGS increased DJ-1 Cys(106)-sulfonate, as a marker of intracellular stress and induced the activation of NF-κB, p53 and c-Jun transcription factors. Additionally, it increased the expression of apoptotic markers Bcl-2 related pro-apoptotic proteins Bax and PUMAand activated caspase-3. The antioxidant N-acetyl-L-cysteine and known pharmacological inhibitors protected the cells from the TPGS induced effects. In conclusion, TPGS selectively induces apoptosis in Jurkat cells through two independent but complementary H2O2-mediated signaling pathways. Our findings support the use of TPGS as a potential treatment for ALL.

Synthetic Cyclic Peptomers as Type III Secretion System Inhibitors

Antibiotic-resistant bacteria are an emerging threat to global public health. New classes of antibiotics and tools for antimicrobial discovery are urgently needed. Type III secretion systems (T3SS), which are required by dozens of Gram-negative bacteria for virulence but largely absent from nonpathogenic bacteria, are promising virulence blocker targets. The ability of mammalian cells to recognize the presence of a functional T3SS and trigger NF-κB activation provides a rapid and sensitive method for identifying chemical inhibitors of T3SS activity. In this study, we generated a HEK293 stable cell line expressing green fluorescent protein (GFP) driven by a promoter containing NF-κB enhancer elements to serve as a readout of T3SS function. We identified a family of synthetic cyclic peptide-peptoid hybrid molecules (peptomers) that exhibited dose-dependent inhibition of T3SS effector secretion in Yersinia pseudotuberculosis and Pseudomonas aeruginosa without affecting bacterial growth or motility. Among these inhibitors, EpD-3'N, EpD-1,2N, EpD-1,3'N, EpD-1,2,3'N, and EpD-1,2,4'N exhibited strong inhibitory effects on translocation of the Yersinia YopM effector protein into mammalian cells (>40% translocation inhibition at 7.5 μM) and showed no toxicity to mammalian cells at 240 μM. In addition, EpD-3'N and EpD-1,2,4'N reduced the rounding of HeLa cells caused by the activity of Yersinia effector proteins that target the actin cytoskeleton. In summary, we have discovered a family of novel cyclic peptomers that inhibit the injectisome T3SS but not the flagellar T3SS.

Xanthohumol inhibits proliferation of laryngeal squamous cell carcinoma

Xanthohumol is a flavonoid compound that exhibits antioxidant and anticancer effects, and is used to treat atherosclerosis. The aim of the present study was to investigate the effect of xanthohumol on the cell proliferation of laryngeal squamous cell carcinoma and to understand the mechanism of its action. The effects of xanthohumol on the cell viability and apoptosis rate of laryngeal squamous cell carcinoma SCC4 cells were assessed by Annexin V-fluorescein isothiocyanate/propidium iodide staining. In addition, the expression levels of pro-apoptotic proteins, caspase-3, caspase-8, caspase-9, poly ADP ribose polymerase (PARP) p53 and apoptosis-inducing factor (AIF), as well as anti-apoptotic markers, B-cell lymphoma 2 (Bcl-2) and myeloid cell leukemia 1 (Mcl-1), were analyzed by western blotting. The results revealed that treatment with 40 µM xanthohumol significantly inhibited the proliferation of SCC4 cells. Furthermore, xanthohumol treatment (40 µM) induced SCC4 cell apoptosis, as indicated by the significant increase in activity and expression of caspase-3, caspase-8, caspase-9, PARP, p53 and AIF. By contrast, the protein expression of Bcl-2 and Mcl-1 was significantly decreased following treatment with 40 µM xanthohumol. Taken together, the results of the present study indicated that xanthohumol mediates growth suppression and apoptosis induction, which was mediated via the suppression of Bcl-2 and Mcl-1 and activation of PARP, p53 and AIF signaling pathways. Therefore, future studies that investigate xanthohumol as a potential therapeutic agent for laryngeal squamous cell carcinoma are required.

Chk1 and DNA-PK mediate TPEN-induced DNA damage in a ROS dependent manner in human colon cancer cells

Recently, we showed that the metal chelator TPEN targets colon cancer cells through redox cycling of copper. Here, we studied the DNA damage potential of TPEN and deciphered the role of Chk1, ATM and DNA-PK in TPEN-induced toxicity in 3 human colon cancer cell lines, HCT116, SW480 and HT29. We also investigated the role of reactive oxygen species (ROS) in TPEN-induced DNA damage. TPEN reduced cell viability in a dose- and time-dependent manner. Cytotoxicity was associated with significant DNA damage and higher expression of γ-H2AX protein and activation of ATM/ATR signaling pathway. Cell death by TPEN was dependent on ROS generation as evidenced by the reversal of cell viability, and DNA damage and the abrogation of γ-H2AX levels in the presence of antioxidants. Treatment with antioxidants, however, failed to reverse cytotoxicity at high TPEN concentrations (10µM). TPEN-induced cell death was also dependent on the redox cycling of copper since the copper chelator neocuproine inhibited DNA damage and reduced pChk1, γ-H2AX, and ATM protein expression. Cell death by low TPEN concentrations, involved ATM/ATR signaling in all 3 cell lines, since pre-incubation with specific inhibitors of ATM and DNA-PK led to the recovery of cells from TPEN-induced DNA damage. In addition, siRNA silencing of Chk1, DNA-PK and ATM abrogated the expression of γ-H2AX and reversed cell death, suggesting that Chk1 and DNA-PK mediate TPEN-induced cytotoxicity in colon cancer cells. This study shows for the first time the involvement of Chk1, DNA-PK and ATM in TPEN-induced DNA damage and confirms our previous findings that ROS generation and the redox cycling of copper in response to TPEN are the main mechanisms by which this compound induces cell death in human colon cancer cells. Inhibition of ATM or DNA-PK did not reverse cytotoxicity at high TPEN concentrations that cause excessive levels of ROS and irreversible cellular damage.

Prostate-specific membrane antigen-targeted liposomes specifically deliver the Zn(2+) chelator TPEN inducing oxidative stress in prostate cancer cells

AIM

To evaluate the potential use of zinc chelation for prostate cancer therapy using a new liposomal formulation of the zinc chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)-ethylenediamine (TPEN).

MATERIALS & METHODS

TPEN was encapsulated in nontargeted liposomes or liposomes displaying an aptamer to target prostate cancer cells overexpression prostate-specific membrane antigen. The prostate cancer selectivity and therapeutic efficacy of liposomal (targeted and nontargeted) and free TPEN were evaluated in vitro and in tumor-bearing mice.

RESULTS & CONCLUSION

TPEN chelates zinc and results in reactive oxygen species imbalance leading to cell death. Delivery of TPEN using aptamer-targeted liposomes results in specific delivery to targeted cells. In vivo experiments show that TPEN-loaded, aptamer-targeted liposomes reduce tumor growth in a human prostate cancer xenograft model.

Anticancer effect of xanthohumol induces growth inhibition and apoptosis of human liver cancer through NF-κB/p53-apoptosis signaling pathway

Xanthohumol may prevent and cure diabetes and atherosis, have oxidation resistance and antiviral function as well as anticancer effect preventing cancer cell metastasis. We investigate whether the anticancer effect of xanthohumol induces growth inhibition and apoptosis of human liver cancer through NF-κB/p53-apoptosis signaling pathway. Human liver cancer HepG2 cell were treated with 10, 20, 30 and 40 µM xanthohumol for 48 h. The present study showed that the anticancer effect of xanthohumol was effective in inhibiting proliferation and inducing apoptosis of human liver cancer HepG2 cells. Furthermore, the caspase-3 activity of human liver cancer HepG2 cells was increased by xanthohumol. In addition, 48-h treatment with xanthohumol suppressed NF-κB expression and promoted p53, cleaved PARP, AIF and cytochrome c expression and downregulated XIAP and Bcl-2/Bax expression in human liver cancer HepG2 cells. Therefore, the anticancer effect of xanthohumol induces growth inhibition and apoptosis of human liver cancer through the NF-κB/p53-apoptosis signaling pathway.

Doxorubicin induces apoptosis in Jurkat cells by mitochondria-dependent and mitochondria-independent mechanisms under normoxic and hypoxic conditions

In this study, we investigated the molecular mechanism of doxorubicin (dxr)-induced cytotoxicity on Jurkat cells - a model cell of human acute lymphoblastic leukemia - under normoxic (20% O2) and hypoxic (5% O2) conditions. Using in-cell western analysis, immunofluorescence, flow cytometry analysis, and biochemical inhibitors, we evaluated several oxidative stress (OS) and cell death markers. It was found that dxr (5-100 μmol/l) induced apoptosis by OS mechanisms involving DNA fragmentation (8-48%), loss of mitochondrial membrane potential (ΔΨm, 33-92%), and H2O2 production (15-42%) under normoxia. In addition, dxr (10 μmol/l) induced activation and/or nuclei translocation of NF-κB (6.6, 1.6-fold increase), p53 (4.3, 3.1 f), c-Jun (9.5, 5.0 f), apoptosis-inducing factor (AIF) (1.9, 3.9 f), caspase-3 (3.7, 1.9 f), overexpression of Parkin (2.1, 1.2 f)/PINK-1 (2.1 f) proteins, and reduced DJ-1 levels by half compared with untreated cells under normoxia, according to immunofluorescence and in-cell western analysis, respectively. In contrast, dxr (10 μmol/l) could not induce apoptosis in Jurkat cells under hypoxia. Effectively, dxr significantly reduced DNA fragmentation (6%), expression levels of cell death (e.g. p53, c-Jun, caspase-3, AIF), and OS (e.g. Parkin) markers, whereas it increased ΔΨm, hypoxia-inducible factor 1-α (HIF-1α, 3.1, 2.3 f), NF-κB (6.8, 2.0 f), and DJ-1 (1.3, 1.0 f) levels. This investigation suggests that dxr might efficiently eliminate acute lymphoblastic leukemia cells by OS-induced apoptosis under normoxic conditions through a minimal completeness of cell death signaling (i.e. mitochondria-caspase-3/AIF-dependent pathways) and through a direct DNA damage process. However, hypoxic conditions may reduce the effectiveness of dxr toxicity.

Disulphide-reduced psoriasin is a human apoptosis-inducing broad-spectrum fungicide

The unexpected resistance of psoriasis lesions to fungal infections suggests local production of an antifungal factor. We purified Trichophyton rubrum-inhibiting activity from lesional psoriasis scale extracts and identified the Cys-reduced form of S100A7/psoriasin (redS100A7) as a principal antifungal factor. redS100A7 inhibits various filamentous fungi, including the mold Aspergillus fumigatus, but not Candida albicans. Antifungal activity was inhibited by Zn(2+), suggesting that redS100A7 interferes with fungal zinc homeostasis. Because S100A7-mutants lacking a single cysteine are no longer antifungals, we hypothesized that redS100A7 is acting as a Zn(2+)-chelator. Immunogold electron microscopy studies revealed that it penetrates fungal cells, implicating possible intracellular actions. In support with our hypothesis, the cell-penetrating Zn(2+)-chelator TPEN was found to function as a broad-spectrum antifungal. Ultrastructural analyses of redS100A7-treated T. rubrum revealed marked signs of apoptosis, suggesting that its mode of action is induction of programmed cell death. TUNEL, SYTOX-green analyses, and caspase-inhibition studies supported this for both T. rubrum and A. fumigatus. Whereas redS100A7 can be generated from oxidized S100A7 by action of thioredoxin or glutathione, elevated redS100A7 levels in fungal skin infection indicate induction of both S100A7 and its reducing agent in vivo. To investigate whether redS100A7 and TPEN are antifungals in vivo, we used a guinea pig tinea pedes model for fungal skin infections and a lethal mouse Aspergillus infection model for lung infection and found antifungal activity in both in vivo animal systems. Thus, selective fungal cell-penetrating Zn(2+)-chelators could be useful as an urgently needed novel antifungal therapeutic, which induces programmed cell death in numerous fungi.

Zinc deficiency during in vitro maturation of porcine oocytes causes meiotic block and developmental failure

The present study investigated the effects of zinc deficiency during in vitro maturation (IVM) of porcine oocytes. Zinc deficiency was induced by administering the membrane‑permeable zinc chelator N,N,N',N'‑tetrakis‑(2‑pyridylmethyl)‑ethylendiamine (TPEN). First, the effects of zinc deficiency during IVM on a TPEN‑treated group and a TPEN+zinc-treated group compared with a control group were assessed. The oocyte maturation rates and subsequent embryonic developmental competence of the TPEN+zinc‑treated oocytes were similar to those of the control oocytes (metaphase II [MII] rate, 93.0 and 92.7%, respectively, and blastocyst [BL] formation rate, 42.0 and 40.0%, respectively). These results were significantly different from those obtained for the TPEN‑treated oocytes (MII rate, 0.61%; BL formation rate, 0%). Although the TPEN‑treated oocytes were arrested at metaphase I (MI), the distribution of microtubules was normal. However, microfilament formation was abnormal in the TPEN‑treated oocytes. Furthermore, the effect of a temporary zinc deficiency during IVM on oocyte maturation and subsequent embryonic development was assessed. TPEN (10 µM) was added to the IVM medium for 0, 7, 15 or 22 h. The 0 h‑treated oocytes showed an 83.9% MII rate, while the 7 h‑treated oocytes had a significantly lower MII rate (44.8%). Most of the 15- and 22 h‑treated oocytes were arrested at MI (MI rate: 98.0 and 97.2%, respectively; MII rate, 0% in both groups). Reductions in the BL formation were dependent on the TPEN treatment duration (29.3, 9.2, 0, and 0% after 0, 7, 15 and 22 h, respectively). In conclusion, zinc is an essential element for successful oocyte maturation and embryonic development in pigs. Zinc deficiency caused a meiotic block and had lasting effects on early embryonic development.

Investigating drug induced changes in single, living lymphocytes based on Raman micro-spectroscopy

Raman spectroscopy is a powerful tool for label-free, single cell characterization. In many reported studies, a Raman spectrum is acquired from a fraction of the cell volume and used as a representative signature of the whole cell to identify and discriminate between cell populations. It has remained an open question whether this is the most suitable approach since the spectra may not truly represent the cell as a whole and critical biochemical information could therefore be lost. To address this question, we developed a line-scan Raman microscope to acquire Raman images of single lymphocytes exposed to the chemotherapeutic drug doxorubicin for 24 to 96 hours. Principal component analysis was able to separate cells based on their drug-exposure times. Difference spectra on the mean data for the different time-points revealed that changes are related to a decrease in mean nucleic acid content and an increase in mean protein and lipid content. Vertex component analysis was used to extract the pure component spectra of lipids, nucleic acids, and proteins. Quantitative analysis of the data revealed that biochemical changes occurred at both local subcellular (i.e. molecular density) and global cellular (i.e. total observable molecular content) levels. However, significant differences between the trends in the local and global changes were observed. While local nucleic acid content decreased with increasing drug exposure time, the total cellular nucleic acid content remained relatively constant. For protein, local content remained relatively constant for all exposure times while the total protein content in the cell increased ∼3 fold. Lipid content in the entire cell increased ∼5 fold, compared to a smaller increase in lipid at the local level. These results show that valuable information about the biochemical changes throughout the entire cell can be missed if only Raman spectra of localized cell regions are used. These findings are expected to have a major impact on the future development of Raman spectroscopy for cytometry applications.

Pig oocyte activation using a Zn²⁺ chelator, TPEN

Artificial oocyte activation is a critical step during SCNT. Most current activation protocols focus on inducing an increase in the intracellular free Ca(2+) concentration of the oocyte. Here, we have used a zinc chelator, TPEN, to enhance the efficiency of oocyte activation during SCNT. TPEN treatment of matured pig oocytes resulted in the reduction of available Zn(2+) in pig oocytes; however, the cytosolic Ca(2+) concentration in the oocytes was not affected by the TPEN treatment. When various concentrations (100-250 μM) and incubation durations (45 minutes-2.5 hours) of TPEN were used to activate oocytes, the efficiency of oocyte activation was not different from conventional activation methods. When oocytes that were activated by conventional activation methods were incubated with a lower concentration of TPEN (5-10 μM), a significant increase in embryos developing to the blastocyst stage was observed. In addition, when oocytes receiving a small Ca(2+) stimulus were further activated by higher concentration of TPEN (100-200 μM), a significant increase in the frequency of blastocyst formation was observed, compared to a conventional activation method. This result indicated that TPEN can be a main reagent in oocyte activation. No increase in the cytosolic Ca(2+) level was detected when oocytes were exposed to various concentrations of TPEN, indicating the ability of TPEN to induce oocyte activation is independent of an intracellular Ca(2+) increase. We were able to produce clones through SCNT by using the TPEN-assisted activation procedure, and the piglets produced through the process did not show any signs of abnormality. In this study, we have developed an efficient way to use TPEN to increase the developmental potential of cloned embryos.

Characterization of Zinc Influx Transporters (ZIPs) in Pancreatic β Cells: ROLES IN REGULATING CYTOSOLIC ZINC HOMEOSTASIS AND INSULIN SECRETION

Zinc plays an essential role in the regulation of pancreatic β cell function, affecting important processes including insulin biosynthesis, glucose-stimulated insulin secretion, and cell viability. Mutations in the zinc efflux transport protein ZnT8 have been linked with both type 1 and type 2 diabetes, further supporting an important role for zinc in glucose homeostasis. However, very little is known about how cytosolic zinc is controlled by zinc influx transporters (ZIPs). In this study, we examined the β cell and islet ZIP transcriptome and show consistent high expression of ZIP6 (Slc39a6) and ZIP7 (Slc39a7) genes across human and mouse islets and MIN6 β cells. Modulation of ZIP6 and ZIP7 expression significantly altered cytosolic zinc influx in pancreatic β cells, indicating an important role for ZIP6 and ZIP7 in regulating cellular zinc homeostasis. Functionally, this dysregulated cytosolic zinc homeostasis led to impaired insulin secretion. In parallel studies, we identified both ZIP6 and ZIP7 as potential interacting proteins with GLP-1R by a membrane yeast two-hybrid assay. Knock-down of ZIP6 but not ZIP7 in MIN6 β cells impaired the protective effects of GLP-1 on fatty acid-induced cell apoptosis, possibly via reduced activation of the p-ERK pathway. Therefore, our data suggest that ZIP6 and ZIP7 function as two important zinc influx transporters to regulate cytosolic zinc concentrations and insulin secretion in β cells. In particular, ZIP6 is also capable of directly interacting with GLP-1R to facilitate the protective effect of GLP-1 on β cell survival.

NaCl pretreatment attenuates H.pylori-induced DNA damage and exacerbates proliferation of gastric epithelial cells (GES-1)

Background

Both H. pylori infection and high salt (NaCl) diet are risks of gastric cancer, however, the interaction pattern of the two is not very clear. Our objective was to investigate the effects of NaCl-pretreated H. pylori on DNA damage and proliferation of gastric epithelial cell (GES-1).

Methods

GES-1 cells were co-cultured with H.pylori or NaCl-pretreated H. pylori (with 30% NaCl) for 24 h. The morphological changes of all cells were observed by inverted phase contrast microscopy and transmission electron microscopy. Oxidative DNA damage was examined by immunofluorescence. Alterations in mitochondrial membrane potential and apoptosis rate were detected by flow cytometry and western blot, and expression of Ki-67, PCNA and P21 were evaluated using the immunocytochemical staining.

Results

GES-1 cells co-cultured with NaCl-pretreated H.pylori exhibited morphological changes and oxidative DNA damage. Although no significant disruption of the mitochondrial membrane potential (ΔΨm) and apoptotic rate were observed compared with control groups, there were significant decreased in Bax and Caspase3 proteins and increased in Bcl-2 protein in GES-1 cells infected with H. pylori³⁰ when compared with GES-1 cells cultured with H. pylori. In addition, we found a proliferative effect on GES-1 cells with an increased expression of Ki-67 and PCNA as well as a decreased p21 expression, through which the cells may acquire the potential for malignant transformation.

Conclusion

NaCl-pretreated H. pylori possessed the ability to cause cell injury and promote proliferation in gastric epithelial cells.

Influence of intracellular zinc on cultures of rat cardiac neural crest cells

BACKGROUND

Developmental zinc (Zn) deficiency increases the incidence of heart anomalies in rat fetuses, in regions and structures derived from the outflow tract. Given that the development of the outflow tract requires the presence of cardiac neural crest cells (cNCC), we speculated that Zn deficiency selectively kills cNCC and could lead to heart malformations.

METHODS

Cardiac NCC were isolated from E10.5 rat embryos and cultured in control media (CTRL), media containing 3 μM of the cell permeable metal chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), or in TPEN-treated media supplemented with 3 μM Zn (TPEN + Zn). Cardiac NCC were collected after 6, 8, and 24 h of treatment to assess cell viability, proliferation, and apoptosis.

RESULTS

The addition of TPEN to the culture media reduced free intracellular Zn pools and cell viability as assessed by low ATP production, compared to cells grown in control or Zn-supplemented media. There was an accumulation of reactive oxygen species, a release of mitochondrial cytochrome c into the cytoplasm, and an increased cellular expression of active caspase-3 in TPEN-treated cNCC compared to cNCC cultured in CTRL or TPEN + Zn media.

CONCLUSION

Zn deficiency can result in oxidative stress in cNCC, and subsequent decreases in their population and metabolic activity. These data support the concept that Zn deficiency associated developmental heart defects may arise in part as a consequence of altered cNCC metabolism.

Metal toxicity and the p53 protein: an intimate relationship

The relationship between p53, ROS and transition metals.

Assessment of circulating biochemical markers and antioxidative status in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) patients

Various circulating biochemical markers are indicators of pathological state in leukemia and its subtypes. Increased oxidative stress and decreased antioxidant factors portray clear image associated with malignancies during subtypes of leukemia. In this research work we investigated the inter-relationship among the subtypes of leukemia with circulating biochemical markers and oxidative stress in the Pakistani population. This research work was conducted on a total number of 70 subjects in which 20 were control participants and 50 were suffering from leukemia and divided into two subtypes (ALL and AML). Various circulating biomarkers were investigated including hematological, hepatic and renal profiles as well as oxidative stress markers, electrolytes and vitamins C and E. Results show that vitamin E was found to be decreased in diseased sub-types (P < 0.05). Malondialdehyde (MDA) levels were very high in disease sub-types (ALL-B = 8.69 ± 1.59; ALL-T = 8.78 ± 0.97; AML = 8.50 ± 1.29) compared to controls (1.22 ± 0.10; P < 0.05) while the levels of antioxidants [superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH), catalase (CAT)], platelets, as well as electrolytes (Ca and Mg) were reduced in patients suffering from leukemia (sub-types). Enhanced levels of oxidative stress (MDA) and decreased levels of enzymatic and non-enzymatic antioxidants reflect the pathological state and impaired cell control in patients suffering from leukemia (subtypes) and show a strong correlation with oxidative stress, indicating that patients' biological systems are under oxidative stress.

Study on the apoptosis mechanism induced by T-2 toxin

T-2 toxin is known to induce apoptosis in mammalian cells. The mechanism of apoptosis induced by T-2 toxin has been proposed to be linked with oxidative stress and mitochondrial pathway. In the current study, the toxic effect of T-2 on Hela, Bel-7402, and Chang liver cells was examined in dose-dependent and time-dependent manner by MTT assay. Caspase-3 was found to be up-regulated under T-2 toxin stress, which suggested that T-2 toxin induced cell apoptosis. Endogenous GSH and MDA levels in all three cell lines were found down- and up-regulated respectively, which indicated the link between toxic effect of T-2 toxin and intracellular oxidative stress. It was also found by MTT assay that NAC, which maintained the level of GSH in cells, could protect cells from death. Western-blot result showed that the level of both activated Caspase-8 and Caspase-9 increased when cells were treated by T-2 toxin. Caspase-9 was found to be activated earlier than Caspase-8. It was also found that p53 was up-regulated under T-2 toxin stress in the study. These results implied that the effect of T-2 toxin on cells was apoptosis rather than necrosis, and it was probably induced through mitochondrial pathway. To the best of our knowledge, the present study is the first to show that JunD is down-regulated in T-2 toxin induced apoptosis. By construction of an over-expression vector for the JunD gene, we observed that the survival ratio of JunD over-expressed cells obviously increased under T-2 toxin stress. These results suggested that the mechanism of T-2 induced cell death was closely connected with oxidative stress, and that JunD plays an important role in the defensive process against T-2 toxin stress.