David Bernhard

The histone deacetylase inhibitor and chemotherapeutic agent suberoylanilide hydroxamic acid (SAHA) induces a cell-death pathway characterized by cleavage of Bid and production of reactive oxygen species.

Many chemotherapeutic agents induce mitochondrial-membrane disruption to initiate apoptosis. However, the upstream events leading to drug-induced mitochondrial perturbation have remained poorly defined. We have used a variety of physiological and pharmacological inhibitors of distinct apoptotic pathways to analyze the manner by which suberoylanilide hydroxamic acid (SAHA), a chemotherapeutic agent and histone deacetylase inhibitor, induces cell death. We demonstrate that SAHA initiates cell death by inducing mitochondria-mediated death pathways characterized by cytochrome c release and the production of reactive oxygen species, and does not require the activation of key caspases such as caspase-8 or -3. We provide evidence that mitochondrial disruption is achieved by means of the cleavage of the BH3-only proapoptotic Bcl-2 family member Bid. SAHA-induced Bid cleavage was not blocked by caspase inhibitors or the overexpression of Bcl-2 but did require the transcriptional regulatory activity of SAHA. These data provide evidence of a mechanism of cell death mediated by transcriptional events that result in the cleavage of Bid, disruption of the mitochondrial membrane, and production of reactive oxygen species to induce cell death.

Smoking and Cardiovascular Disease Mechanisms of Endothelial Dysfunction and Early Atherogenesis

Smoking represents one of the most important preventable risk factors for the development of atherosclerosis. The present review aims at providing a comprehensive summary of published data from clinical and animal studies, as well as results of basic research on the proatherogenic effect of smoking. Extensive search and review of literature revealed a vast amount of data on the influence of cigarette smoke and its constituents on early atherogenesis, particularly on endothelial cells. Vascular dysfunction induced by smoking is initiated by reduced nitric oxide (NO) bioavailability and further by the increased expression of adhesion molecules and subsequent endothelial dysfunction. Smoking-induced increased adherence of platelets and macrophages provokes the development of a procoagulant and inflammatory environment. After transendothelial migration and activation, macrophages take up oxidized lipoproteins arising from oxidative modifications and transdifferentiate into foam cells. In addition to direct physical damage to endothelial cells, smoking induces tissue remodeling, and prothrombotic processes together with activation of systemic inflammatory signals, all of which contribute to atherogenic vessel wall changes. There are still great gaps in our knowledge about the effects of smoking on cardiovascular disease. However, we know that smoking cessation is the most effective measure for reversing damage that has already occurred and preventing fatal cardiovascular outcomes. # Significance {#article-title-77}

Replicative senescence of human endothelial cells in vitro involves G1 arrest, polyploidization and senescence-associated apoptosis

Human ageing is characterized by a progressive loss of physiological functions, increased tissue damage and defects in various tissue renewal systems. Age-related decreases of the cellular replicative capacity can be reproduced by in vitro assays of cellular ageing. When diploid human fibroblasts reach their finite lifespan, they enter an irreversible G1 growth arrest status referred to as replicative senescence. While deregulation of programmed cell death (apoptosis) is a key feature of age-related pathology in several tissues, this is not reflected in the standard in vitro senescence model of human fibroblasts, and the role of apoptosis during cellular ageing remains unclear. We have analyzed replicative senescence of human umbilical vein endothelial cells (HUVEC) in vitro and found that senescent HUVEC also arrest in the G1 phase of the cell cycle but, unlike fibroblasts, accumulate with a 4N DNA content, indicative of polyploidization. In contrast to human fibroblasts, senescent endothelial cells display a considerable increase in spontaneous apoptosis. The data imply that age-dependent apoptosis is a regular feature of human endothelial cells and suggest cell type specific differences in human ageing.

Resveratrol, a tumor-suppressive compound from grapes, induces apoptosis via a novel mitochondrial pathway controlled by Bcl-2

We report that resveratrol (3,5,4′‐trihydroxy‐trans‐stilbene), a phytoalexin found in grapes and other plant food, induced a breakdown of the mitochondrial transmembrane potential (∆Ψm) in T‐acute lymphoblastic leukemia cells and swelling of isolated rat mitochondria. The breakdown of ∆Ψm was accompanied by the production of reactive oxygen species (ROS), and preceded phosphatidylserine exposure and DNA fragmentation. Breakdown of ∆Ψm was not caused by the activation of caspase‐8 or Bid, as no significant cleavage of these proteins could be detected in the induction phase of resveratrol‐induced apoptosis. Though loss of ∆Ψm was not followed by cytochrome c translocation to the cytosol, the mitochondrial changes triggered significant activation of caspase‐9, ‐2, ‐3, and ‐6. Inhibition of ∆Ψm breakdown and of ROS generation by N‐acetylcysteine, or by overexpression of Bcl‐2 protein, prevented apoptosis induction by resveratrol. The Bcl‐2 expression status of tumor cells should therefore be considered relevant for potential clinical application of resveratrol as anticancer agent.

Smoking and Cardiovascular Disease

Smoking represents one of the most important preventable risk factors for the development of atherosclerosis. The present review aims at providing a comprehensive summary of published data from clinical and animal studies, as well as results of basic research on the proatherogenic effect of smoking. Extensive search and review of literature revealed a vast amount of data on the influence of cigarette smoke and its constituents on early atherogenesis, particularly on endothelial cells. Vascular dysfunction induced by smoking is initiated by reduced nitric oxide (NO) bioavailability and further by the increased expression of adhesion molecules and subsequent endothelial dysfunction. Smoking-induced increased adherence of platelets and macrophages provokes the development of a procoagulant and inflammatory environment. After transendothelial migration and activation, macrophages take up oxidized lipoproteins arising from oxidative modifications and transdifferentiate into foam cells. In addition to direct physical damage to endothelial cells, smoking induces tissue remodeling, and prothrombotic processes together with activation of systemic inflammatory signals, all of which contribute to atherogenic vessel wall changes. There are still great gaps in our knowledge about the effects of smoking on cardiovascular disease. However, we know that smoking cessation is the most effective measure for reversing damage that has already occurred and preventing fatal cardiovascular outcomes. # Significance {#article-title-77}

Cadmium Is a Novel and Independent Risk Factor for Early Atherosclerosis Mechanisms and In Vivo Relevance

Objectives—Although cadmium (Cd) is an important and common environmental pollutant and has been linked to cardiovascular diseases, little is known about its effects in initial stages of atherosclerosis. Methods and Results—In the 195 young healthy women of the Atherosclerosis Risk Factors in Female Youngsters (ARFY) study, cadmium (Cd) level was independently associated with early atherosclerotic vessel wall thickening (intima-media thickness exceeding the 90th percentile of the distribution; multivariable OR 1.6[1.1.–2.3], P=0.016). In line, Cd-fed ApoE knockout mice yielded a significantly increased aortic plaque surface compared to controls (9.5 versus 26.0 mm2, P<0.004). In vitro results indicate that physiological doses of Cd increase vascular endothelial permeability up to 6-fold by (1) inhibition of endothelial cell proliferation, and (2) induction of a caspase-independent but Bcl-xL-inhibitable form of cell death more than 72 hours after Cd addition. Both phenomena are preceded by Cd-induced DNA strand breaks and a cellular DNA damage response. Zinc showed a potent protective effect against deleterious effects of Cd both in the in vitro and human studies. Conclusion—Our research suggests Cd has promoting effects on early human and murine atherosclerosis, which were partly offset by high Zn concentrations.

Resveratrol causes arrest in the S-phase prior to Fas-independent apoptosis in CEM-C7H2 acute leukemia cells

Resveratrol (3,5,4′-trihydroxy-trans-stilbene), in the concentration range of 20 μM and above, induced arrest in the S-phase and apoptosis in the T cell-derived T-ALL lymphocytic leukemia cell line CEM-C7H2 which is deficient in functional p53 and p16. Expression of transgenic p16/INK4A, which causes arrest in G0/G1, markedly reduced the percentage of apoptotic cells. Antagonist antibodies to Fas or FasL, or constitutive expression of crmA did not diminish the extent of resveratrol-induced apoptosis. Furthermore, a caspase-8-negative, Fas-resistant Jurkat cell line was sensitive to resveratrol-induced apoptosis which could be strongly inhibited in the Jurkat as well as in the CEM cell line by z-VAD-fmk and z-IETD-fmk. The almost complete inhibition by z-IETD-fmk and the lack of inhibition by crmA suggested caspase-6 to be the essential initiator caspase. Western blots revealed the massive conversion of procaspase-6 to its active form, while caspase-3 and caspase-2 were proteolytically activated to a much lesser extent. Cell Death and Differentiation (2000) 7, 834–842

Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphoblasts

The histone deacetylase inhibitor and potential anti‐cancer drug sodium butyrate is a general inducer of growth arrest, differentiation, and in certain cell types, apoptosis. In human CCRF‐CEM, acute T lymphoblastic leukemia cells, butyrate, and other histone deacetylase inhibitors caused G2/M cell cycle arrest as well as apoptotic cell death. Forced G0/G1 arrest by tetracycline‐regulated expression of transgenic p16/INK4A protected the cells from butyrate‐induced cell death without affecting the extent of histone hyperacetylation, suggesting that the latter may be necessary, but not sufficient, for cell death induction. Nuclear apoptosis, but not G2/M arrest, was delayed but not prevented by the tripeptide broad‐range caspase inhibitor benzyloxycarbonyl‐Val‐Ala‐Asp·fluoromethylketone (zVAD) and, to a lesser extent, by the tetrapeptide ‘effector caspase’ inhibitors benzyloxycarbonyl‐Asp‐Glu‐Val‐Asp·fluoromethylketone (DEVD) and benzyloxycarbonyl‐Val‐Glu‐Ile‐Asp‐fluoromethyl‐ketone (VEID); however, the viral protein inhibitor of ‘inducer caspases’, crmA, had no effect. Bcl‐2 overexpression partially protected stably transfected CCRF‐CEM sublines from butyrate‐induced apoptosis, but showed no effect on butyrate‐induced growth inhibition, further distinguishing these two butyrate effects. c‐myc, constitutively expressed in CCRF‐CEM cells, was down‐regulated by butyrate, but this was not causative for cell death. On the contrary, tetracycline‐induced transgenic c‐myc sensitized stably transfected CCRF‐CEM derivatives to butyrate‐induced cell death.—Bernhard, D., Ausserlechner, M. J., Tonko, M., Löffler, M., Hartmann, B. L., Csordas, A., Kofler, R. Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphoblasts. FASEB J. 13, 1991–2001 (1999)

Metals in cigarette smoke

Metals are vital for a huge number of physiological processes in the human body, but can also destroy health when the concentration is not within the physiologically favourable range. Cigarette smoking interferes with the carefully controlled metal homeostasis of the human body. This review focuses on the consequences of metal delivery to the human body by cigarette smoking and discusses the bodys responses. The metal content of tobacco plants, smoke, the circulation, and various organs is discussed. Finally, we link individual cigarette smoke contained metals to the genesis of human diseases.

Enhanced MTT-reducing activity under growth inhibition by resveratrol in CEM-C7H2 lymphocytic leukemia cells

Inhibition of proliferation by resveratrol of CEM-C7H2 lymphocytic leukemia cells was paradoxically associated with an enhanced cellular 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT)-reducing activity. This phenomenon was most pronounced at the sub-apoptotic concentration range of 5-20 microM resveratrol. The results of our study show that the MTT-reducing activity can be increased by the polyphenolic antioxidant resveratrol without a corresponding increase in the number of living cells and that this occurs at a concentration range of the antioxidant which is not sufficient to induce apoptosis but suffices to slow down cell growth. This phenomenon appears to be restricted to proliferation inhibitors with antioxidant properties and is cell type-specific. Thus, in determining the effects of flavonoids and polyphenols on proliferation, in certain cell types this might represent a pitfall in the MTT proliferation assay.