Apoptosis provoked by the oxidative stress inducer menadione (Vitamin K(3)) is mediated by the Fas/Fas ligand system

Vitamin K: New insights related to senescence and cancer metastasis

Several clinical trials and experimental studies have recently shown that vitamin K (VK) supplementation benefits the human body. Specifically, VK participates in coagulation and is associated with cellular senescence and cancer. VK has a potential anticancer effect in various cancers, such as pancreatic and prostate cancers. Through anti-inflammatory and antioxidant effects, VK can prevent senescence and inhibit cancer metastasis. Therefore, cancer prognosis can be improved by preventing cellular senescence. In addition, VK can inhibit the proliferation, growth, and differentiation of cancer cells through various mechanisms, including induction of c-myc and c-fos genes, regulation of B-cell lymphoma-2 (Bcl-2) and p21 genes, and angiogenesis inhibition. This review aims to discuss the relationship among VK, cellular senescence, and cancer metastasis and thus may improve comprehension of the specific functions of VK in human health. The potential application of VK as an adjuvant therapy for cancer (or in combination with traditional chemotherapy drugs or other vitamins) has also been highlighted.

Dietary Vitamin K Intake and HPV-Infection Status Among American Women: A Secondary Analysis From National Health and Nutrition Examination Survey Data From 2003 to 2016

Objective: Cervical cancer is a serious potential risk to women’s health, and is closely related to persistent HPV infection. Vitamin K mainly existed in green vegetables, fruit, and dairy products. This research aims to observe the association between vitamin K and HPV-infection.

Methods: 13,447 participants from the NHANES were selected. Dietary vitamin K intake was used as the objective independent variable and continuous variable, HPV-infection status was used as the outcome variable, and characteristics of selected participants were used as the covariates.

Results: There was a nonlinearity between vitamin K intake and HPV-infection, and the inflection point is 3.81 of log2 vitamin K intake. In a range of 0–3.81, Each one-unit increase in log2 vitamin K intake was associated with a 43% reduction in the risk of HPV infection. When log2 vitamin K intake excess of 3.81, the risk of HPV infection did not continue to decline. The HPV-subtype was not associated with vitamin K intake.

Conclusion: There is a nonlinearity between vitamin K intake and HPV-infection status. But HPV-subtype was not associated with vitamin K intake.

Apoptotic Effects of a Thioether Analog of Vitamin K3 in a Human Leukemia Cell Line

Research suggests that thioether analogs of vitamin K₃ (VK₃) can act to preserve the phosphorylation of epidermal growth factor receptors by blocking enzymes (phosphatases) responsible for their dephosphorylation. Additionally, these derivatives can induce apoptosis via mitogen-activated protein kinase and caspase-3 activation, inducing reactive oxygen species (ROS) production, and apoptosis. However, vitamin K₁ exhibits only weak inhibition of phosphatase activity, while the ability of VK₃ to cause oxidative DNA damage has raised concerns about carcinogenicity. Hence, in the current study, we designed, synthesized, and screened a number of VK₃ analogs for their ability to enhance phosphorylation activity, without inducing off-target effects, such as DNA damage. 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay revealed that each analog produced a different level of cytotoxicity in the Jurkat human leukemia cell line; however, none elicited a cytotoxic effect that differed significantly from that of the control. Of the VK₃ analogs, CPD5 exhibited the lowest EC₅₀, and flow cytometry results showed that apoptosis was induced at final concentrations of ≥10 μM; hence, only 0.1, 1, and 10 μM were evaluated in subsequent assays. Furthermore, CPD5 did not cause vitamin K-attributed ROS generation and was found to be associated with a significant increase in caspase 3 expression, indicating that, of the synthesized thioether VK₃ analogs, CPD5 was a more potent inducer of apoptosis than VK₃. Hence, further elucidation of the apoptosis-inducing effect of CPD5 may reveal its efficacy in other neoplastic cells and its potential as a medication.

Vitamin K intake and breast cancer incidence and death: results from a prospective cohort study

BACKGROUND & AIMS

Vitamin K prevents growth and metastasis of certain cancers, but there is little evidence regarding the association between dietary vitamin K and breast cancer incidence and death. We sought to examine whether intakes of total vitamin K, phylloquinone (vitamin K1) and menaquinones (MKs) (vitamin K2) may influence risks of breast cancer incidence and death in the US population.

METHODS

Herein, 2286 breast cancer cases and 207 breast cancer deaths were identified during 702,748 person-years of follow-up. Cox regression and competing risk regression were used to estimate multivariable-adjusted hazards ratios (HRs) and 95% confidence intervals (95% CIs) by dietary vitamin K intake quintile (Q) for risk of breast cancer incidence and mortality.

RESULTS

After adjustment for confounders, the total MK intake was associated with an increased risk of breast cancer (HR Q5 vs Q1, 1.26; 95% CI, 1.05 to 1.52; P_trend, 0.01) and death from breast cancer (HR Q5 vs Q1, 1.71; 95% CI, 0.97 to 3.01; P_trend, 0.04). Non-linear positive dose-response associations with risks of breast cancer incidence and death were found for total MKs intake (P_{non-linearity}<0.05). No statistically significant associations were observed between the intake of total vitamin K and phylloquinone and breast cancer.

CONCLUSIONS

The present study suggests that total MK intake was associated with an altered risk of the occurrence and death of breast cancer in the general US population. If our findings are replicated in other epidemiological studies, reducing dietary intake of menaquinones may offer a novel strategy for breast cancer prevention.

Synergistic Effect of Endogenous and Exogenous Aldehydes on Doxorubicin Toxicity in Yeast

Anthracyclines are frequently used to treat many cancers including triple negative breast cancer, which is commonly observed in African-American women (AA), and tend to be more aggressive, carry worse prognoses, and are harder to manage because they lack molecular targets. Although effective, anthracyclines use can be limited by serious side effects and eventually the development of drug resistance. In S. cerevisiae, mutants of HOM6 display hypersensitivity to doxorubicin. HOM6 is required for synthesis of threonine and interruption of the pathway leads to accumulation of the threonine intermediate L-aspartate-semialdehyde. This intermediate may synergize with doxorubicin to kill the cell. In fact, deleting HOM3 in the first step, preventing the pathway to reach the HOM6 step, rescues the sensitivity of the hom6 strain to doxorubicin. Using several S. cerevisiae strains (wild type, hom6, hom3, hom3hom6, ydj1, siz1, and msh2), we determined their sensitivity to aldehydes and to their combination with doxorubicin, cisplatin, and etoposide. Combination of formaldehyde and doxorubicin was most effective at reducing cell survival by 31-fold–39-fold (in wild type cells) relative to doxorubicin and formaldehyde alone. This effect was dose dependent on doxorubicin. Cotreatment with formaldehyde and doxorubicin also showed increased toxicity in anthracycline-resistant strains siz1 and msh2. The hom6 mutant also showed sensitivity to menadione with a 2.5-fold reduction in cell survival. The potential use of a combination of aldehydes and cytotoxic drugs could potentially lead to applications intended to enhance anthracycline-based therapy.

Vitamin K: Redox-modulation, prevention of mitochondrial dysfunction and anticancer effect

This review is directed to the redox-modulating properties and anticancer effect of vitamin K. The concept is focused on two aspects: (i) redox-cycle of vitamin K and its effect on the calcium homeostasis, “oncogenic” and “onco-suppressive” reactive oxygen species and the specific induction of oxidative stress in cancer; (ii) vitamin K plus C as a powerful redox-system, which forms a bypass between mitochondrial complexes II and III and thus prevents mitochondrial dysfunction, restores oxidative phosphorylation and aerobic glycolysis, modulates the redox-state of endogenous redox-pairs, eliminates the hypoxic environment of cancer cells and induces cell death. The analyzed data suggest that vitamin C&K can sensitize cancer cells to conventional chemotherapy, which allows achievement of a lower effective dose of the drug and minimizing the harmful side-effects. The review is intended for a wide audience of readers - from students to specialists in the field.

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

Sulforaphane enhances proteasomal and autophagic activities in mice and is a potential therapeutic reagent for Huntington's disease

The ubiquitin proteasome system (UPS) is impaired in Huntington's disease, a devastating neurodegenerative disorder. Sulforaphane, a naturally occurring compound, has been shown to stimulate UPS activity in cell cultures. To test whether sulforaphane enhances UPS function in vivo, we treated UPS function reporter mice ubiquitously expressing the green fluorescence protein (GFP) fused to a constitutive degradation signal that promotes its rapid degradation in the conditions of a healthy UPS. The modified GFP is termed GFP UPS reporter (GFPu). We found that both GFPu and ubiquitinated protein levels were significantly reduced and the three peptidase activities of the proteasome were increased in the brain and peripheral tissues of the mice. Interestingly, sulforaphane treatment also enhanced autophagy activity in the brain and the liver. To further examine whether sulforaphane promotes mutant huntingtin (mHtt) degradation, we treated Huntington's disease cells with sulforaphane and found that sulforaphane not only enhanced mHtt degradation but also reduced mHtt cytotoxicity. Sulforaphane-mediated mHtt degradation was mainly through the UPS pathway as the presence of a proteasome inhibitor abolished this effect. Taken together, these data indicate that sulforaphane activates protein degradation machineries in both the brain and peripheral tissues and may be a therapeutic reagent for Huntington's disease and other intractable disorders. Accumulation of mutant huntingtin (mHtt) protein causes Huntington's disease (HD). Sulforaphane (SFN), a naturally occurring compound, increased proteasome and autophagy activities in vivo and enhanced mHtt turnover and cell survival in HD cell models. SFN-mediated mHtt degradation is mainly through the proteasome pathway. These data suggest that SFN can be a therapeutic reagent for treating HD and other intractable disorders.

The effect of bicarbonate on menadione-induced redox cycling and cytotoxicity: potential involvement of the carbonate radical

We have investigated the effect of NaHCO3 on menadione redox cycling and cytotoxicity. A cell-free system utilized menadione and ascorbic acid to catalyze a redox cycle, and we utilized murine hepatoma (Hepa 1c1c7) cells for in vitro experiments. Experiments were performed using low (2 mmol/L) and physiological (25 mmol/L) levels of NaHCO3 in buffer equilibrated to physiological pH. Using oximetry, ascorbic acid oxidation, and ascorbyl radical detection, we found that menadione redox cycling was enhanced by NaHCO3. Furthermore, Hepa 1c1c7 cells treated with menadione demonstrated cytotoxicity that was significantly increased with physiological concentrations of NaHCO3 in the media, compared with low levels of NaHCO3. Interestingly, the inhibition of superoxide dismutase (SOD) with 2 different metal chelators was associated with a protective effect against menadione cytotoxicity. Using isolated protein, we found a significant increase in protein carbonyls with menadione-ascorbate-SOD with physiological NaHCO3 levels; low NaHCO3 or SOD-free reactions produced lower levels of protein carbonyls. In conclusion, these findings suggest that the hydrogen peroxide generated by menadione redox cycling together with NaHCO3-CO2 are potential substrates for SOD peroxidase activity that can lead to carbonate-radical-enhanced cytotoxicity. These findings demonstrate the importance of NaHCO3 in menadione redox cycling and cytotoxicity.

Effects of quercetin and menadione on intestinal calcium absorption and the underlying mechanisms

Quercetin (QT) could be considered as a potential therapeutic agent for different diseases due to its antioxidant, anti-inflammatory, antiviral and anticancer properties. This study was designed to investigate the ability of QT to protect the chick intestine against menadione (MEN) induced injury in vivo and in vitro. Four-week old chicks (Gallus gallus) were treated i.p. with 2.5μmol of MEN/kg b.w. or with i.l. 50μM QT or both. QT protected the intestinal Ca(2+) absorption against the inhibition caused by MEN, but QT alone did not modify. Glutathione (GSH) depletion provoked by MEN in chick enterocytes was abolished by QT treatment, whereas QT alone did not modify the intestinal GSH content. The enhancement of GSH peroxidase activity produced by MEN was blocked by QT treatment. In contrast, superoxide dismutase activity remained high after simultaneous treatment of enterocytes with MEN and QT. The flavonol also avoided changes in the mitochondrial membrane permeability (swelling) produced by MEN. The FasL/Fas/caspase-3 pathway was activated by MEN, effect that was abrogated by QT. In conclusion, QT may be useful in preventing inhibition of chick intestinal Ca(2+) absorption caused by MEN or other substances that deplete GSH, by blocking the oxidative stress and the FasL/Fas/caspase-3 pathway activation.

Prostaglandin E2 blocks menadione-induced apoptosis through the Ras/Raf/Erk signaling pathway in promonocytic leukemia cell lines

Altered oxidative stress has long been observed in cancer cells, and this biochemical property of cancer cells represents a specific vulnerability that can be exploited for therapeutic benefit. The major role of an elevated oxidative stress for the efficacy of molecular targeted drugs is under investigation. Menadione is considered an attractive model for the study of oxidative stress, which can induce apoptosis in human leukemia HL-60 cell lines. Prostaglandin E(2) (PGE(2)) via its receptors not only promotes cell survival but also reverses apoptosis and promotes cancer progression. Here, we present evidence for the biological role of PGE(2) as a protective agent of oxidative stress-induced apoptosis in monocytic cells. Pretreatment of HL-60 cells with PGE(2) markedly ameliorated the menadione-induced apoptosis and inhibited the degradation of PARP and lamin B. The EP(2) receptor antagonist AH6809 abrogated the inhibitory effect of PGE(2), suggesting the role of the EP(2)/cAMP system. The PKA inhibitor H89 also reversed apoptosis and decreased the PKA activity that was elevated 10-fold by PGE(2). The treatment of HL-60 cells with NAC or zinc chloride showed a similar protective effect as with PGE(2) on menadione-treated cells. Furthermore, PGE(2) activated the Ras/Raf/MEK pathway, which in turn initiated ERK activation, and ultimately protected menadione-induced apoptosis. These results imply that PGE(2) via cell survival pathways may protect oxidative stress-induced apoptosis in monocytic cells. This study warrants further pre-clinical investigation as well as application towards leukemia clinics.

Vitamin K3 and vitamin C alone or in combination induced apoptosis in leukemia cells by a similar oxidative stress signalling mechanism

BACKGROUND

Secondary therapy-related acute lymphoblastic leukemia might emerge following chemotherapy and/or radiotherapy for primary malignancies. Therefore, other alternatives should be pursued to treat leukemia.

RESULTS

It is shown that vitamin K3- or vitamin C- induced apoptosis in leukemia cells by oxidative stress mechanism involving superoxide anion radical and hydrogen peroxide generation, activation of NF-κB, p53, c-Jun, protease caspase-3 activation and mitochondria depolarization leading to nuclei fragmentation. Cell death was more prominent when Jurkat and K562 cells are exposed to VC and VK3 in a ratio 1000:1 (10 mM: 10 μM) or 100:1 (300 μM: 3 μM), respectively.

CONCLUSION

We provide for the first time in vitro evidence supporting a causative role for oxidative stress in VK3- and VC-induced apoptosis in Jurkat and K562 cells in a domino-like mechanism. Altogether these data suggest that VK3 and VC should be useful in the treatment of leukemia.

Mitochondrial dysfunction is responsible for the intestinal calcium absorption inhibition induced by menadione

Menadione (MEN) inhibits intestinal calcium absorption by a mechanism not completely understood. The aim of this work was to find out the role of mitochondria in this inhibitory mechanism. Hence, normal chicks treated with one i.p. dose of MEN were studied in comparison with controls. Intestinal calcium absorption was measured by the in situ ligated intestinal segment technique. GSH, oxidoreductase activities from the Krebs cycle and enzymes of the antioxidant system were measured in isolated mitochondria. Mitochondrial membrane potential was measured by a flow cytometer technique. DNA fragmentation and cytochrome c localization were determined by immunocytochemistry. Data indicate that in 30 min, MEN decreases intestinal Ca(2+) absorption, which returns to the control values after 10 h. GSH was only decreased for half an hour, while the activity of malate dehydrogenase and alpha-ketoglutarate dehydrogenase was diminished for 48 h. Mn(2+)-superoxide dismutase activity was increased in 30 min, whereas the activity of catalase and glutathione peroxidase remained unaltered. DNA fragmentation and cytochrome c release were maximal in 30 min, but were recovered after 15 h. In conclusion, MEN inhibits intestinal Ca(2+) absorption by mitochondrial dysfunction as revealed by GSH depletion and alteration of the permeability triggering the release of cytochrome c and DNA fragmentation.

Characterization of the SKN7 ortholog of Aspergillus fumigatus

Reactive oxidant intermediates play a major role in the killing of Aspergillus fumigatus by phagocytes. In yeasts, SKN7 is a transcription factor contributing to the oxidative stress response. We investigated here the role of afSkn7p in the adaptation of A. fumigatus against oxidative stress. To analyze functionally the afSKN7 in A. fumigatus, we modified a quick PCR fusion methodology for targeted deletion in A. fumigatus. The afskn7Delta mutant was morphologically similar to the wild-type strain, but showed a growth inhibition phenotype associated with hydrogen peroxide and tert-butyl hydroperoxide. However, no significant virulence differences were observed between wild type, mutant and reconstituted strains in a murine model of pulmonary aspergillosis. This result indicated that an increased sensitivity of A. fumigatus to peroxides in vitro is not correlated with a modification of fungal virulence.

The role of the sakA (Hog1) and tcsB (sln1) genes in the oxidant adaptation of Aspergillus fumigatus

The Hog1 MAP kinase pathway regulates stress adaptation in several fungi. To assess its role in stress adaptation in Aspergillus fumigatus, we constructed mutants in genes encoding the sensor histidine kinase (HK) tcsB as well as sakA, which are homologues of the Saccharomyces cerevisiae sln1 and Hog1, respectively. Compared to the wild type strain (Wt), growth of sakA (sakAtriangle up) mutant was reduced, and growth inhibition was increased when H(2)O(2), menadione, or SDS was added to the media. On the other hand, the tcsB mutant (tcsBtriangle up) was similar to the Wt strain in regard to growth and morphology, although a partial sensitivity to SDS was observed. Western blot analysis of Wt and the tcsBtriangle up strains indicated that when stressed with H(2)O(2), phosphorylation of Hog1p still occurs in the mutant. Since in Candida albicans, Hog1 regulates transcription of at least one histidine kinase, we performed RT-PCR of 6 histidine kinase genes as well as the ssk1 and skn7 response regulator genes of A. fumigatus. No significant differences in transcription were observed with the sakAtriangle up when compared to the Wt, indicating that the sakA does not regulate transcription of these genes. Our studies indicate that the A. fumigatus sakA is required for optimal growth of the organism with or without oxidant stress, while tcsB gene is dispensable.

The switch mechanism of the cell death mode from apoptosis to necrosis in menadione-treated human osteosarcoma cell line 143B cells

Time-dependent changes in the cell death mode from apoptosis to necrosis were studied in cultured 143B cells treated with menadione, an anti-cancerous drug, excluding a possible involvement of "secondary necrosis." The population of apoptotic cells judged by FITC-Annexin V and propidium iodide (PI) double staining reached its maximum at 6 hours after 100 microM menadione treatment followed by an abrupt decrease thereafter, while that of necrotic cells continuously increased reaching 90% at 24 hours. Electron microscopically, cells attached to the culture dish at 6 hours after the treatment consisted of two different types of cells: cells with typical apoptotic features occupying the major population and those with condensed nuclei and swollen cytoplasm. Cells attached to the culture dish at 8 hours after the treatment consisted exclusively of those with condensed nuclei and swollen cytoplasm. Mitochondria in these cells showed various structural changes: those swollen to various degrees with deposition of flocculent densities, or those with highly condensed matrix. Distinct decreases both in intracellular levels of ATP and caspase-3-like activities and remarkable elevations of intracellular levels of superoxide, which were partly suppressed by NAD(P)H oxidase inhibitors, occurred at 6 hours after the treatment. These results may suggest that distinct increases of the intracellular level of superoxide derived from plasma membrane NAD(P)H oxidase besides that from mitochondria have triggered the transition of cell death mode from apoptosis to necrosis. Transition of highly condensed mitochondria to extremely swollen ones may reflect necrotic processes in menadione-treated cells. The present study strongly suggests that time-dependent study is essential using the electron microscopic technique to analyze detailed processes in the changes of the cell death mode.

Effect of resveratrol on high glucose-induced stress in human leukemia K562 cells

Hyperglycemia, a symptom of diabetes mellitus, induces hyperosmotic responses, including apoptosis, in vascular endothelial cells and leukocytes. Hyperosmotic shock elicits a stress response in mammalian cells, often leading to apoptotic cell death. In a previous report, we showed that hyperosmotic shock induced apoptosis in various mammalian cells. Importantly, apoptotic biochemical changes (i.e., caspase-3 activation and DNA fragmentation) were blocked by antioxidant pretreatment during hyperosmotic shock-induced cell death. In the present study, we report that resveratrol, a phytoalexin present in grapes with known antioxidant and anti-inflammatory properties, attenuates high glucose-induced apoptotic changes, including c-Jun N-terminal kinase (JNK) activation and caspase-3 activation in human leukemia K562 cells. Experiments with the cell permeable dye, 2',7'-dichlorofluorescein diacetate (DCF-DA), an indicator of reactive oxygen species (ROS) generation, revealed that high glucose treatment directly increased intracellular oxidative stress, which was attenuated by resveratrol. In addition, high glucose-treated K562 cells displayed a lower degree of attachment to collagen, the major component of vessel wall subendothelium. In contrast, cells pretreated with resveratrol followed by high glucose exhibited higher affinity for collagen. The results of this report collectively imply the involvement of oxidative stress in high glucose-induced apoptosis and alterations in attachment ability. Moreover, resveratrol blocks these events by virtue of its antioxidant property.

Autoschizis: a new form of cell death for human ovarian carcinoma cells following ascorbate:menadione treatment. Nuclear and DNA degradation

Microscopic aspects, densitometric evaluation of Feulgen-stained DNA, and gel electrophoresis of total DNA have been used to elucidate the effects of 1, 2, and 3 h VC (ascorbic acid), VK3 (menadione), and combined VC:VK3 treatments on the cellular and nuclear morphology and DNA content of a human ovarian carcinoma cell line (MDAH 2774). Optical densitometry showed a significant decrease in cancer cell DNA content directly related to VC and VC:VK3 treatments while VK3 and VC:VK3 treated cells exhibited cytoskeletal changes that included self-excision of cytoplasmic pieces with no membranous organelles. Nuclei decreased in size and exhibited poor contrast consistent with progressive decondensation of their chromatin. Degraded chromatin was also detected in cytoplasmic autophagosomes. Nucleoli segregated their components and fragmented into small pieces. Gel electrophoretic analysis of total DNA revealed evidence of generalized DNA degradation specific to treated tumor cells. These results are consistent with previous observations [Scanning 20 (1998a) 564; Ultrastruct. Pathol. 25 (2001b) 183; J. Histochem. Cytochem. 49 (2001) 109] which demonstrated that the VC:VK3 combination induced autoschizic cell death by a series of cytoplasmic excisions without organelles along with specific nuclear ultrastructural damage.

Studies of murine systemic autoimmunity

Systemic autoimmunity is an important clinical problem, offering a window into fundamental questions of self-nonself tolerance. We have used cellular immunology, serology, and immunopathology to approach several spontaneous mouse models. Although much remains to be done, a picture is emerging of pathological antigen-driven immune responses to self nuclear antigens, highly dependent on multiple genes, and susceptible to abnormalities of apoptosis.

Menadione biphasically controls JNK-linked cell death in leukemia Jurkat T cells

Signals for cell-death induction by menadione were studied in Jurkat T cells. Low concentrations of menadione (10-20 microM) and H(2)O(2) (10-50 microM) induced cell death accompanying low (menadione: <5%) or moderate (H(2)O(2): 10-15%) levels of DNA fragmentation in Jurkat cells. These concentrations of menadione (10 microM) and H(2)O(2) also caused membrane (necrotic) cell death at unproportionally high (80%) and proportional (10-30%) levels, respectively. Higher concentrations (100-5,000 microM) of H(2)O(2) exclusively induced membrane cell death. Unexpectedly, 30-300 microM menadione induced ever-decreasing levels of necrotic cell death in a concentration-dependent manner. An in vitro kinase assay showed that 20-50 microM, but not >100 microM, menadione induced activation of c-Jun NH(2)-terminal kinase (JNK), whereas a striking activation of JNK was induced by 500-5,000 microM H(2)O(2). Induction of cell death by a low concentration of menadione was partially inhibited in dominant negative JNK gene-transfected Jurkat/VPF cells. A high concentration (300 microM) of menadione was found to inhibit cell-death induction by high concentrations (200-5,000 microM) of H(2)O(2). The JNK inhibitory activity of menadione was also demonstrated in a cell-free system. However, menadione did not activate JNK in vitro. These results suggest that JNK is required for induction of not only apoptotic cell death, but also necrotic cell death in Jurkat T cells and that menadione biphasically controls this JNK-linked signal for inducing cell death.

Molecular dissection of alleles of the osmotic-1 locus of Neurospora crassa

Two-component histidine kinases of bacteria, plants, and fungi are involved in the regulation of intracellular events in response to changes in external environmental conditions. Fungal histidine kinases play important roles in osmoregulation, in vivo and in planta virulence, and sensitivity to certain classes of antifungals. The osmotic-1 (OS-1) locus of Neurospora crassa encodes a predicted protein with homology to histidine kinases and appears to be an osmosensor. Mutants of the OS-1 locus are hypersensitive to salt and are strongly resistant to dicarboximide antifungals. Molecular analysis of each of eight OS-1 mutants revealed that seven resulted from amino acid changes in a domain of the protein known as the linker region. These results indicate that the linker region of fungal two-component histidine kinases is essential for proper functioning of the kinase.

p53 dependent apoptosis in glioma cell lines in response to hydrogen peroxide induced oxidative stress

Generation of reactive oxygen species (ROS) is an important mode of action of many chemotherapeutic agents. Hydrogen peroxide (H(2)O(2)) is a model oxidant that has been used to study the response of cells to oxidative stress. The role of p53 in ROS induced cell death has not been consistent and has been shown to be cell type dependent. Study of cellular and molecular parameters and mechanisms involved in H(2)O(2) induced cell death in glioma cells will contribute to the understanding of response of these cells to oxidative stress. We investigated induction of cell death by H(2)O(2), and its relation to p53 in two human glial tumor derived cell lines U87MG (wild type p53) and U373MG (mutated p53). We observed that H(2)O(2) was able to induce apoptosis (as shown by morphology, flow cytometry and DNA fragmentation studies) in U87MG in a dose dependent manner. Dimethyl sulfoxide (DMSO), a known ROS scavenger, was protective to the cells. H(2)O(2) induced cell death was significantly reduced by antisense p53 oligonucleotide. Pretreatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of the redox sensitive transcription factor NF-kappa B, abrogated the increased expression of p53 protein in response to H(2)O(2), and enhanced cell survival. The U373MG cell line, having mutated p53, was comparatively resistant to H(2)O(2) induced cell death. We conclude from the study that p53, activated by NF-kappa B, is essential for H(2)O(2) induced apoptosis in glioma cells.

Evidence that oxidative stress-induced apoptosis by menadione involves Fas-dependent and Fas-independent pathways

Menadione (vitamin K3) a redox cycling quinone, is a clinically important chemotherapeutic agent. The objective of this study was to clarify the cytotoxic mechanisms by which menadione induces cell death in a lymphoblastoid cell line. Our results show that while the Jun kinase cascade and FasL expression may contribute to cell death at lower drug concentrations, a mitochondrial pathway dominates the cytotoxic effect at higher menadione concentrations. Menadione treatment clearly affected the mitochondrial function of Jurkat T cells by inducing a collapse of the inner transmembrane potential (DeltaPsi(m)) and a decrease in inner membrane mass, which could be completely reversed by N-acetylcysteine. Importantly, while a broad range of fmk-derived caspase inhibitors had potent effects on Fas-induced apoptosis, they failed to interfere in menadione cytotoxicity, indicating that menadione-induced cell death is predominantly Fas-independent. In addition, the mitochondrial changes coincided with ATP depletion. The failure in ATP production explains the occurrence of Fas-independent death events.

Cellular stress response and apoptosis in cancer therapy

Anticancer treatment using cytotoxic drugs is considered to mediate cell death by activating key elements of the apoptosis program and the cellular stress response. While proteolytic enzymes (caspases) serve as main effectors of apoptosis, the mechanisms involved in activation of the caspase system are less clear. Two distinct pathways upstream of the caspase cascade have been identified. Death receptors, eg, CD95 (APO-1/Fas), trigger caspase-8, and mitochondria release apoptogenic factors (cytochrome c, Apaf-1, AIF), leading to the activation of caspase-9. The stressed endoplasmic reticulum (ER) contributes to apoptosis by the unfolded protein response pathway, which induces ER chaperones, and by the ER overload response pathway, which produces cytokines via nuclear factor-kappaB. Multiple other stress-inducible molecules, such as p53, JNK, AP-1, NF-kappaB, PKC/MAPK/ERK, and members of the sphingomyelin pathway have a profound influence on apoptosis. Understanding the complex interaction between different cellular programs provides insights into sensitivity or resistance of tumor cells and identifies molecular targets for rational therapeutic intervention strategies.

Ultrastructural aspects of autoschizis: a new cancer cell death induced by the synergistic action of ascorbate/menadione on human bladder carcinoma cells

Scanning and transmission electron microscopy were employed to further characterize the cytotoxic effects of a ascorbic acid/menadione (or vitamin C/vitamin K3) combination on a human bladder carcinoma T24 cell line. Following 1-h treatment T24 cells display membrane and mitochondrial defects as well as excision of cytoplasmic fragments that contain no organelles. These continuous self-excisions reduce the cell size. Concomitant, nuclear changes, chromatin disassembly, nucleolar condensation and fragmentation, and decreased nuclear volume lead to cell death via a process similar to karyorrhexis and karyolysis. Because this cell death is achieved through a progressive loss of cytoplasm due to self-morsellation, the authors named this mode of cell death autoschizis (from the Greek autos, self, and schizein, to split, as defined in Scanning. 1998; 20: 564-575). This morphological characterization of autoschizic cell death confirms and extends the authors previous reports and demonstrates that this cell death is distinct from apoptosis.

Apoptosis and liver diseases: recent concepts of mechanism and significance

Apoptosis, or programmed cell death, is a highly conserved mechanism that plays an essential role in numerous normal developmental and regulatory processes and disease states. It is mediated by a variable interaction among several components of the cell, including cell surface death receptors, the caspase cascade, mitochondrial metabolism and energetics, and the cytoskeleton. Even in those instances in which cell surface death receptors play a role, mitochondria are often central to the process, not only in mediating the death program, but in initiating it as well. In regard to mitochondrial involvement, a key role is hypothesized for an interaction among AMP-activated protein kinase, cytoskeletal intermediate filaments, and mitochondrial oxidation of fatty acids. This proposed interaction may be a critical element in the pathogenesis of intramitochondrial oxidative stress, diminished inner membrane potential (delta psi(m)), and other mitochondrial changes that contribute to cell death. Apoptosis may participate in a wide variety of disease processes, ranging from chemical and physical injury to viral infection and cancer, but its mechanistic and functional relationship to these conditions remains incompletely understood. Despite this, an understanding of the mechanisms involved and of the identity of potential pharmacologic targets is increasing, and warrants an optimistic view of their potential for clinical application.

The isolation of FOS-1, a gene encoding a putative two-component histidine kinase from Aspergillus fumigatus

In fungi, two-component histidine kinases are involved in response mechanisms to extracellular changes in osmolarity, resistance to dicarboximide fungicides, and cell-wall assembly. In the human opportunistic fungus, Candida albicans, each of the three histidine kinases plays a role in virulence. Here, we identify, for the first time, a gene, FOS-1, from the human pathogenic fungus Aspergillus fumigatus that predicts a protein with homology to two-component histidine kinases. The predicted FOS-1 protein is highly homologous to bacterial and other fungal histidine kinases in several functional domains, but is divergent at the amino- and carboxy-termini. A mutant lacking the FOS-1 locus, DeltaFOS-1, did not exhibit a detectable defect in either hyphal growth or morphology when grown on solid or liquid medium. However, in liquid medium, conidiophore development of the DeltaFOS-1 mutant was delayed. Compared to wild type, the DeltaFOS-1 strain was neither osmotically sensitive nor sensitive or resistant to a number of nondicarboximide antifungal drugs, but was highly resistant to dicarboximide fungicides and resistant to novozym 234, suggesting that FOS-1p may play a role in the regulation of cell-wall assembly.

Reactive oxidizing species produced near the plasma membrane induce apoptosis in bovine aorta endothelial cells

Many cytotoxic agents initiate apoptosis by generating reactive oxidizing species (ROS). The goal of this study was to determine whether apoptosis could be induced by initial reactions of ROS near the plasma membrane. Bovine aorta endothelial cells (BAEC) were illuminated with evanescent wave visible radiation, which has limited penetration into the basal surface of cells, or by trans-radiation. Imaging of fluorescent dyes localizing in the plasma membrane, mitochondria, or nucleus confirmed that evanescent wave radiation excited only dyes in and near the plasma membrane. Singlet oxygen, an ROS generated by photosensitization, has a very short lifetime, ensuring that it oxidizes molecules residing in or very close to the plasma membrane when evanescent wave radiation is used. Cells with condensed nuclei were considered apoptotic and were quantified after treatment with varying doses of light. Annexin V staining without propidium iodide staining confirmed that these cells were apoptotic. The doses required to induce apoptosis using evanescent wave radiation were 10-fold greater than those needed for trans-irradiation. Quantitative analysis of the evanescent wave penetration into cells supports a mechanism in which the singlet oxygen created near the plasma membrane, rather than at intracellular sites, was responsible for initiation of apoptosis.

Inhibition of UV irradiation-induced oxidative stress and apoptotic biochemical changes in human epidermal carcinoma A431 cells by genistein

Ultraviolet (UV) light is a strong apoptotic trigger that can induce a caspase-dependent biochemical change in cells. We previously showed that UV irradiation can elicit caspase-3 activation and the subsequent cleavage and activation of p21-activated kinase 2 (PAK2) in human epidermal carcinoma A431 cells. We report that genistein, an isoflavone compound with known inhibitory activities to protein tyrosine kinases (PTKs) and topoisomerase-II (topo-II), can prevent UV irradiation-induced apoptotic biochemical changes (DNA fragmentation, caspase-3 activation, and cleavage/activation of PAK2) in A431 cells. Surprisingly, two typical PTK inhibitors (tyrphostin A47 and herbimycin A) and three known topo-II inhibitors (etoposide, daunorubicin, and novomycin) had no effect on UV irradiation-induced apoptotic biochemical changes, suggesting that the inhibitory effect of genistein is not dependent on its property as a PTK/topo-II inhibitor. In contrast, azide, a reactive oxygen species (ROS) scavenger, could effectively block the UV irradiation-induced apoptotic cell responses. Flow cytometric analysis using the cell-permeable dye 2',7'-dichlorofluorescin diacetate as an indicator of the generation of ROS showed that UV irradiation caused increase of the intracellular oxidative stress and that this increase could be abolished by azide, suggesting that oxidative stress plays an important role in mediating the apoptotic effect of UV irradiation. Importantly, the UV irradiation-induced oxidative stress in cells could be significantly attenuated by genistein, suggesting that impairment of ROS formation during UV irradiation is responsible for the antiapoptotic effect of genistein. Collectively, our results demonstrate the involvement of oxidative stress in the UV irradiation-induced caspase activation and the subsequent apoptotic biochemical changes and show that genistein is a potent inhibitor for this process.