Apoptosis induced by microtubule disrupting drugs in cultured human lymphoma cells. Inhibitory effects of phorbol ester and zinc sulphate

PICT1 is critical for regulating the Rps27a-Mdm2-p53 pathway by microtubule polymerization inhibitor against cervical cancer

In our previous study, it showed that P-3F, a podophyllotoxin derivative, causes the increased level of p53 expression by enhancing p53 stability, resulting from blockage of the Mdm2-p53 feedback loop via nucleolus-to-nucleoplasm translocation of Rps27a in human cervical cancer HeLa cell line. However, the mechanism of regulating Rps27a localization remains to be studied. In the current study, it has been demonstrated that the level of protein interacting with carboxyl terminus 1 (PICT1), originally identified as a tumor suppressor, was decreased in a concentration-dependent manner in response to P-3F, leading to inhibition of human cervical cancer cell lines proliferation. Also remarkably, reduction of serine phosphorylation of STMN1 at position 16 induced by P-3F was required in the downregulation of PICT1, in which p53 activity was likely to be directly involved. Note as well that, PICT1 also played an important role in p53 stability enhancement by inhibiting Mdm2-mediated p53 ubiquitination due to Rps27a translocation from the nucleolus to the nucleoplasm to interact with Mdm2 following treatment with P-3F. Collectively, these findings indicated that P-3F, a microtubule polymerization inhibitor, promotes the decreased level of PICT1 expression, which is critical for regulating the Rps27a-Mdm2-p53 pathway against cervical cancer.

The hepatoprotective and antioxidative effect of saffron stigma alcoholic extract against vincristine sulfate induced toxicity in rats

Vincristine (VCR) is an important anti-cancer drug, which is highly toxic for the liver. This study aimed at evaluating the protective effect of alcoholic extract of saffron stigma against vincristine hepatotoxicity in the rat. A total number of 50 rats were randomly divided into 10 groups, including controls, rats receiving 0.25 mg/kg (A group), 0.5 mg/kg (B group), 0.75 mg/kg (C group) VCR, 0.25 mg/kg VCR + 0.5 mg/kg saffron (D group), 0.5 mg/kg VCR + 0.5 mg/kg saffron (E group), 0.75 mg/kg VCR + 0.5 mg/kg saffron (F group), 0.25 mg/kg VCR + 1mg/kg saffron (G group), 0.5 mg/kg VCR + 1 mg/kg saffron (H group), and 0.75 mg/kg VCR + 1 mg/kg saffron (I group) groups. Serum level of liver enzymes, including aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and bilirubin were measured using specific kits at the end of the experimental period. Serum total antioxidant capacity (TAC) and malondialdehyde (MDA) values were measured using ferric reducing antioxidant of power (FRAP) and thiobarbituric acid reaction (TBAR) methods, respectively. Administration of VCR, especially at the concentration of 0.75mg/kg, caused severe hepatic injury with significant increase in the levels of AST (582.0±39.45 UI), ALT (124.0±5.92 UI), ALP (939.8±89.8 UI) enzymes and bilirubin (0.17±0.008). VCR administration also significantly increased the serum MDA level (0.49±0.021 nmol/ml), while TAC value was declined significantly (241.27±18.27 μmol/l). These effects were dose-dependent. Treatment with saffron extract decreased the activity of liver enzymes and MDA values in hepatotoxic rats with a significant enhancement in serum TAC content. These effects were notable for rats that received 1mg/kg plant extract. Administration of saffron, especially at higher concentration, can reduce VCR-induced hepatotoxicity, antioxidant depletion and lipid peroxidation, presumably due to its antioxidative properties.

Nujiangexathone A, a Novel Compound Derived from Garcinia nujiangensis, Induces Caspase-Dependent Apoptosis in Cervical Cancer through the ROS/JNK Pathway

Nujiangexathone A (NJXA), a novel compound derived from Garcinia nujiangensis, has been demonstrated to inhibit the proliferation of several human cancer cell lines. This study is the first to demonstrate the apoptosis inductive activities of NJXA and the possible underlying mechanisms. Our results demonstrated that NJXA inhibited colony formation by HeLa and SiHa cells in a dose-dependent manner. An Annexin V-FITC/PI staining assay showed that NJXA strongly triggered apoptosis in a dose-dependent manner. Western blotting analyses showed that NJXA induced the caspase-dependent apoptosis of HeLa and SiHa cells by triggering a series of events, including changes in the levels of Bcl-2 family proteins, cytochrome c release, caspase-3 activation, and chromosome fragmentation. Furthermore, we demonstrated that NJXA induced cell apoptosis by activating the reactive oxygen species (ROS)-mediated JNK signaling pathway. Consistent with this finding, a ROS scavenger, N-acetyl-l-cysteine (NAC, 10 mM), hindered NJXA-induced apoptosis and attenuated the sensitivity of HeLa and SiHa cells to NJXA. In vivo results further confirmed that the tumor inhibitory effect of NJXA was partially through the induction of apoptosis. Taken together, our results demonstrated that NJXA induced the apoptosis of HeLa and SiHa cells through the ROS/JNK signaling pathway, indicating that NJXA could be important candidate for the clinical treatment of cervical cancer.

Label free high throughput screening for apoptosis inducing chemicals using time-lapse microscopy signal processing

Label free time-lapse microscopy has opened a new avenue to the study of time evolving events in living cells. When combined with automated image analysis it provides a powerful tool that enables automated large-scale spatiotemporal quantification at the cell population level. Very few attempts, however, have been reported regarding the design of image analysis algorithms dedicated to the detection of apoptotic cells in such time-lapse microscopy images. In particular, none of the reported attempts is based on sufficiently fast signal processing algorithms to enable large-scale detection of apoptosis within hours/days without access to high-end computers. Here we show that it is indeed possible to successfully detect chemically induced apoptosis by applying a two-dimensional linear matched filter tailored to the detection of objects with the typical features of an apoptotic cell in phase-contrast images. First a set of recorded computational detections of apoptosis was validated by comparison with apoptosis specific caspase activity readouts obtained via a fluorescence based assay. Then a large screen encompassing 2,866 drug like compounds was performed using the human colorectal carcinoma cell line HCT116. In addition to many well known inducers (positive controls) the screening resulted in the detection of two compounds here reported for the first time to induce apoptosis.

Characterization of proapoptotic compounds from the bark of Garcinia oblongifolia

Twenty compounds from Garcinia oblongifolia were screened for proapoptotic activity using FRET-based HeLa-C3 sensor cells. Among them, oblongifolins F and G (1 and 2), 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthone (3), nigrolineaxanthone T (4), and garcicowin B (5) showed significant proapoptotic activity at a concentration of 10 μM. Bioassessments were then performed to evaluate the potential of these compounds for therapeutic application. All five compounds showed significant cytotoxicity and caspase-3-activating ability in cervical cancer HeLa cells, with compounds 1 and 2 having the highest potencies. All five compounds specifically induced caspase-dependent apoptosis, which could be prevented by the pan-caspase inhibitor zVAD-fmk. In particular, 3 induced apoptosis through mitotic arrest. Compounds 1-5 displayed similar IC50 values (3.9-16.5 μM) against the three cancer cell lines HeLa, MDA-MB-435, and HepG2. In addition, compounds 1, 2, and 4 exhibited similar and potent IC50 values (2.4-5.1 μM) against several breast and colon cancer cell lines, including those overexpressing either HER2 or P-glycoprotein. HER2 and P-glycoprotein are known factors that confer resistance to anticancer drugs in cancer cells. This is the first study on the cytotoxicity, caspase-3-activing ability, and specificity of proapoptotic compounds isolated from G. oblongifolia in HeLa cells. The potential application of these compounds against HER2- or P-glycoprotein-overexpressing cancer cells was investigated.

A novel polysaccharide from Ganoderma atrum exerts antitumor activity by activating mitochondria-mediated apoptotic pathway and boosting the immune system

Ganoderma is a precious health-care edible medicinal fungus in China. A novel Ganoderma atrum polysaccharide (PSG-1) is the main bioactive component. We investigated the antitumor effect and molecular mechanisms of PSG-1. It exhibited no significant effect on cell proliferation directly. In contrast, administration of PSG-1 markedly suppressed tumor growth in CT26 tumor-bearing mice. It was observed that PSG-1 caused apoptosis in CT26 cells. Apoptosis was associated with loss of mitochondrial membrane potential, enhancement of mitochondrial cytochrome c release and intracellular ROS production, elevation of p53 and Bax expression, downregulation of Bcl-2, and the activation of caspase-9 and -3. Moreover, PSG-1 enhanced immune organ index and promoted lymphocyte proliferation as well as cytokine levels in serum. Taken together, our data indicate that PSG-1 has potential antitumor activity in vivo by inducing apoptosis via mitochondria-mediated apoptotic pathway and enhances host immune system function. Therefore, PSG-1 could be a safe and effective antitumor, bioactive agent or functional food.

Pharmacokinetic evaluation of vincristine for the treatment of lymphoid malignancies

INTRODUCTION

Vincristine is a key agent for the treatment of acute lymphoblastic leukemia (ALL) and other lymphoid malignancies. The strong antineoplastic activity of vincristine has been limited by its pharmacological characteristics.

AREAS COVERED

This paper reviews the role of vincristine in the treatment of lymphoid malignancies. This review summarizes its efficacy and toxicity, and focuses on the pharmacokinetic features of vincristine that affect clinical outcomes.

EXPERT OPINION

As a single agent, vincristine is associated with brief and incomplete responses, but in combination with other agents, vincristine has dramatically improved the outcomes of lymphoid malignancies such as ALL. Vincristine is a key drug of hyper-fractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, an intensive chemotherapeutic regimen for the treatment of ALL, and of cyclophosphamid, adriamycin, vincristine and prednisone, which has been used extensively in the treatment of patients with aggressive or indolent lymphomas and Richter syndrome. The strong antileukemic activity of vincristine has been limited by its variable and unpredictable pharmacological characteristics, narrow therapeutic index and neurotoxicity profile. These characteristics prompted the development of liposomal vincristine, which has optimized its clinical application. Liposomal vincristine has promising antileukemic activity, and it is approved by the FDA as a single agent for the treatment of relapsed/refractory Philadelphia chromosome-negative ALL.

Marqibo® (vincristine sulfate liposome injection) improves the pharmacokinetics and pharmacodynamics of vincristine

Vincristine (VCR) is a mainstay of treatment of hematologic malignancies and solid tumors due to its well-defined mechanism of action, demonstrated anticancer activity and its ability to be combined with other agents. VCR is an M-phase cell cycle-specific anticancer drug with activity that is concentration and exposure duration dependent. The pharmacokinetic profile of standard VCR is described by a bi-exponential elimination pattern with a very fast initial distribution half-life followed by a longer elimination half-life. VCR also has a large volume of distribution, suggesting diffuse distribution and tissue binding. These properties may limit optimal drug exposure and delivery to target tissues as well as clinical utility as a single agent or as an effective component of multi-agent regimens. Vincristine sulfate liposome injection (VSLI), Marqibo^®, is a sphingomyelin and cholesterol-based nanoparticle formulation of VCR that was designed to overcome the dosing and pharmacokinetic limitations of standard VCR. VSLI was developed to increase the circulation time, optimize delivery to target tissues and facilitate dose intensification without increasing toxicity. In xenograft studies in mice, VSLI had a higher maximum tolerated dose, superior antitumor activity and delivered higher amounts of active drug to target tissues compared to standard VCR. VSLI recently received accelerated FDA approval for use in adults with advanced, relapsed and refractory Philadelphia chromosome-negative ALL and is in development for untreated adult ALL, pediatric ALL and untreated aggressive NHL. Here, we summarize the nonclinical data for VSLI that support its continued clinical development and recent approval for use in adult ALL.

Novel microtubule polymerization inhibitor with potent antiproliferative and antitumor activity

Microtubule-stabilizing and microtubule-destabilizing agents are commonly used as anticancer agents. Although highly effective, success with these agents has been limited due to their relative insolubility, cumbersome synthesis/purification, toxic side effects, and development of multidrug resistance. Hence, the identification of improved agents that circumvent one or more of these problems is warranted. We recently described the rational design of a series of triazole-based compounds as antimitotic agents. Members of this N-substituted 1,2,4-triazole family of compounds exhibit potent tubulin polymerization inhibition and broad spectrum cellular cytotoxicity. Here, we extensively characterize the in vitro and in vivo effects of our lead compound from the series 1-methyl-5-(3-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazole-4-yl)-1H-indole, designated T115. We show that T115 competes with colchicine for its binding pocket in tubulin, produces robust inhibition of tubulin polymerization, and disrupts the microtubule network system inside the cells. In addition, T115 arrests human cancer cells in the G(2)-M phase of cell cycling, a hallmark of microtubule destabilizing drugs. T115 also inhibits cell viability of several cancer cell lines, including multidrug-resistant cell lines, in the low nanomolar range. No cytotoxicity was observed by T115 against normal human skin fibroblasts cell lines, and acute toxicity studies in normal nontumor-bearing mice indicated that T115 is well-tolerated in vivo (maximum total tolerated dose, 400 mg/kg). In a mouse xenograft model using human colorectal (HT-29) and prostate (PC3) cancer cells, T115 significantly inhibited tumor growth when administered i.p. Taken together, our results suggest that T115 is a potential drug candidate for cancer chemotherapy.

An approach to achieve long-term expression in skin gene therapy

For gene therapy purposes, the skin is an attractive organ to target for systemic delivery of therapeutic proteins to treat systemic diseases, skin diseases, or skin cancer. To achieve long-term stable expression of a therapeutic gene in keratinocytes (KC), we have developed an approach using a bicistronic retroviral vector expressing the desired therapeutic gene linked to a selectable marker (multidrug resistant gene, MDR) that is then introduced into KC and fibroblasts (FB) to create genetically modified human skin equivalent (HSE). After grafting the HSE onto immunocompromised mice, topical colchicine treatment is used to select and enrich for genetically modified keratinocyte stem cells (KSC) that express MDR and are resistant to colchicine's antimitotic effects. Both the apparatus for topical colchicine delivery and the colchicine doses have been optimized for application to human skin. This approach can be validated by systemic delivery of therapeutic factors such as erythropoietin and the antihypertensive atrial natriuretic peptide.

A high throughput drug screen based on fluorescence resonance energy transfer (FRET) for anticancer activity of compounds from herbal medicine

BACKGROUND AND PURPOSE

We report the development of a very efficient cell-based high throughput screening (HTS) method, which utilizes a novel bio-sensor that selectively detects apoptosis based on the fluorescence resonance energy transfer (FRET) technique.

EXPERIMENTAL APPROACH

We generated a stable HeLa cell line expressing a FRET-based bio-sensor protein. When cells undergo apoptosis, they activate a protease called 'caspase-3'. Activation of this enzyme will cleave our sensor protein and cause its fluorescence emission to shift from a wavelength of 535 nm (green) to 486 nm (blue). A decrease in the green/blue emission ratio thus gives a direct indication of apoptosis. The sensor cells are grown in 96-well plates. After addition of different chemical compounds to each well, a fluorescence profile can be measured at various time-points using a fluorescent plate reader. Compounds that can trigger apoptosis are potential candidates as anti-cancer drugs.

KEY RESULTS

This novel cell-based HTS method is highly effective in identifying anti-cancer compounds. It was very sensitive in detecting apoptosis induced by various known anti-cancer drugs. Further, this system detects apoptosis, but not necrosis, and is thus more useful than the conventional cell viability assays, such as those using MTT. Finally, we used this system to screen compounds, isolated from two plants used in Chinese medicine, and identified several effective compounds for inducing apoptosis.

CONCLUSIONS AND IMPLICATIONS

This FRET-based HTS method is a powerful tool for identifying anti-cancer compounds and can serve as a highly efficient platform for drug discovery.

Toxic epidermal necrolysis: current evidence, practical management and future directions

Toxic epidermal necrolysis (TEN) is a rare disorder characterized by extensive epidermal death. Almost all cases appear to be caused by an idiosyncratic drug reaction. Proposed pathogenic mechanisms are conflicting, and the evidence for the benefits of individual treatments is inadequate, and in some cases contradictory. The mortality rate remains high. We review the literature pertaining to the pathogenesis of TEN and drug reactions in general. The rationale for therapeutic interventions, together with reported evidence of efficacy, are considered. We present a composite model of TEN, based on previous work and suggested pathogeneses of TEN, mechanisms of drug reactions and reported cytotoxic lymphocyte (CTL) cytolytic pathways. In this system, TEN, like some other cutaneous drug eruptions, is an HLA class I-restricted, specific drug sensitivity, resulting in clonal expansion of CD8+ CTLs. Cytotoxicity is mediated by CTL granzyme and possibly death receptor (DR) ligand (DR-L), probably Fas ligand (FasL). Particular to TEN, there is then an amplification sequence involving further DR-L expression. FasL is likely to be particularly important but tumour necrosis factor (TNF) may well contribute, via the TNF receptor 1 (TNF-R1) death pathway. Alternatively, we suggest the possibility of upregulation of an antiapoptotic TNF-R1-nuclear factor kappaB pathway, which would proscribe treatments which downregulate this pathway. None of the published data on individual treatment efficacies is sufficiently strong to suggest a definitive single treatment. Currently a multifaceted regimen appears indicated, targeting various likely intermediary mechanisms, including elimination of residual drug, immunosuppression, inhibition of DR pathways, general antiapoptotic strategies, and aggressive supportive care. Particular attention has been directed at avoiding potential conflicts between different treatments and avoiding agents that theoretically might have a net proapoptotic rather than antiapoptotic effect. Nursing on a specialized unit is of paramount importance.

Pharmacokinetic studies in children with cancer

We reviewed the current status of our knowledge of pharmacokinetics and pharmacodynamics of some anti-neoplastic drugs, used in the treatment of childhood cancer. Extrapolation of data from pharmacokinetic studies in adults to the paediatric population is often not feasible. Specific studies in children are needed. Of all reviewed anti-neoplastic drugs methotrexate appears to be most extensively studied. Methotrexate pharmacokinetics is correlated with toxicity and response to therapy, and it has been shown that individualized adaptive dosing of methotrexate is correlated with a better response to therapy without increasing toxicity in children with ALL and osteosarcoma. Of most of the other reviewed anti-neoplastic drugs it is demonstrated that pharmacokinetics is correlated with toxicity, and of some drugs a relationship of pharmacokinetics with response to therapy is demonstrated as well. In case of cytarabine, etoposide, and teniposide, individualized dosing also appears to be feasible. However, there is no evidence that this strategy improves response to therapy. Specifically data on pharmacokinetic and pharmacodynamic correlations and effect of pharmacokinetically guided, individualized dosing are important for the design of optimal cancer chemotherapy for individual patients. Unfortunately for a considerable number of anti-neoplastic drugs these specific data are lacking in children and future research is needed.

Zinc inhibits Bax and Bak activation and cytochrome c release induced by chemical inducers of apoptosis but not by death-receptor-initiated pathways

Zinc has been known for many years to inhibit apoptosis but the mechanism remains unclear. Originally thought to inhibit an apoptotic endonuclease, zinc has subsequently been shown to inhibit steps earlier in the pathway. Since many additional steps in apoptosis have now been defined, we have re-evaluated the steps inhibited by zinc. In response to activation of the chemical-mediated death pathway by anisomycin, 0.3 mM zinc inhibited Bax and Bak activation, cytochrome c release, and all of the subsequent steps in apoptosis. In the receptor-mediated death pathway initiated by Fas or tumor necrosis factor, 3 mM zinc was required to inhibit apoptosis as judged by inhibition of caspase 3 activity and DNA digestion, but it failed to inhibit cytochrome c release, activation of Bax and Bak, or upstream signaling events in this pathway. These results are consistent with zinc selectively inhibiting activation of BH3-only proteins required in the chemical pathway but inhibiting downstream caspase activation in the death-receptor pathway.

Pharmacokinetics of vincristine monotherapy in childhood acute lymphoblastic leukemia

We studied vincristine pharmacokinetics in 70 children newly diagnosed with acute lymphoblastic leukemia, after a single dose of vincristine as monotherapy. Vincristine plasma concentrations were measured by HPLC analysis. A two-compartment, first-order pharmacokinetic model was fitted to the data by maximum a posteriori parameter estimation. In this group of children pharmacokinetic factors were highly variable: median (25th and 75th percentiles) total body clearance, 228 (128-360) mL.min(-1).m(-2); elimination half-life, 1001 (737-1325) min; apparent volume of distribution at steady state 262 (158-469) L/m(2). Vincristine clearance was substantially slower than has been reported previously for children receiving vincristine in combination with steroids as part of combination chemotherapy (median clearance, 228 mL.min(-1).m(-2) versus mean clearance, 381 and 482 mL. min(-1). m(-2), respectively). Steroids are known as inducers of vincristine-metabolizing cytochrome P(450) 3A4 enzymes. The absence of steroids during our study appears to be the most likely explanation for this difference. Furthermore, we found that vincristine clearance was faster in patients with hyperdiploid (>50 chromosomes) than in patients with diploid or hyperdiploid (46-50 chromosomes) leukemic blasts.

Modern views on an ancient chemical: serotonin effects on cell proliferation, maturation, and apoptosis

Evolutionarily, serotonin existed in plants even before the appearance of animals. Indeed, serotonin may be tied to the evolution of life itself, particularly through the role of tryptophan, its precursor molecule. Tryptophan is an indole-based, essential amino acid which is unique in its light-absorbing properties. In plants, tryptophan-based compounds capture light energy for use in metabolism of glucose and the generation of oxygen and reduced cofactors. Tryptophan, oxygen, and reduced cofactors combine to form serotonin. Serotonin-like molecules direct the growth of light-capturing structures towards the source of light. This morphogenic property also occurs in animal cells, in which serotonin alters the cytoskeleton of cells and thus influences the formation of contacts. In addition, serotonin regulates cell proliferation, migration and maturation in a variety of cell types, including lung, kidney, endothelial cells, mast cells, neurons and astrocytes). In brain, serotonin has interactions with seven families of receptors, numbering at least 14 distinct proteins. Of these, two receptors are important for the purposes of this review. These are the 5-HT1A and 5-HT2A receptors, which in fact have opposing functions in a variety of cellular and behavioral processes. The 5-HT1A receptor develops early in the CNS and is associated with secretion of S-100beta from astrocytes and reduction of c-AMP levels in neurons. These actions provide intracellular stability for the cytoskeleton and result in cell differentiation and cessation of proliferation. Clinically, 5-HT1A receptor drugs decrease brain activity and act as anxiolytics. The 5-HT2A receptor develops more slowly and is associated with glycogenolysis in astrocytes and increased Ca(++) availability in neurons. These actions destabilize the internal cytoskeleton and result in cell proliferation, synaptogenesis, and apoptosis. In humans, 5-HT2A receptor drugs produce hallucinations. The dynamic interactions between the 5-HT1A and 5-HT2A receptors and the cytoskeleton may provide important insights into the etiology of brain disorders and provide novel strategies for their treatment.

Protein kinase C inhibits singlet oxygen-induced apoptosis by decreasing caspase-8 activation

Although activation of protein kinase C (PKC) inhibits apoptosis induced by a variety of stimuli including singlet oxygen, the step at which PKC activation interferes with apoptotic signaling is not well defined. We have shown previously that caspase-8 and p38 mediate singlet oxygen-induced apoptosis in HL-60 cells. In this study, we investigated the influence of PKC on regulation of the caspase and p38 pathways initiated by singlet oxygen. Singlet oxygen induced Fas clustering and subsequent recruitment of FADD and caspase-8. Treatment of cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a PKC activator, did not affect the binding of caspase-8 to the aggregated Fas. Surprisingly, under the same conditions PKC activation was still able to prevent singlet oxygen-induced activation of caspase-8 and block its downstream signaling events including cleavage of Bid and caspase-3, decrease in mitochondrial transmembrane potential and release of cytochrome c from mitochondria. Inhibition of PKC by GF109203 or H7 counteracted the TPA-mediated effects on the cleavage of caspases -3 and -8. However, neither activation nor inhibition of PKC affected p38 phosphorylation. These data indicate that PKC inhibits singlet oxygen-induced apoptosis by blocking activation of caspase-8.

Bcl-2 over-expression and activation of protein kinase C suppress the trail-induced apoptosis in Jurkat T cells

Trail, a tumor necrosis factor-related apoptosis-inducing ligand, is a novel potent endogenous activator of the cell death pathway through the activation of cell surface death receptors Trail-R1 and Trail-R2. Its role, like FasL in activation-induced cell death (AICD), has been demonstrated in immune system. However the mechanism of Trail induced apoptosis remains unclear. In this report, the recombinant Trail protein was expressed and purified. The apoptosis-inducing activity and the regulation mechanism of recombinant Trail on Jurkat T cells were explored in vitro. Trypan blue exclusion assay demonstrated that the recombinant Trail protein actively killed Jurkat T cells in a dose-dependent manner. Trail-induced apoptosis in Jurkat T cells were remarkably reduced by Bcl-2 over expression in Bcl-2 gene transfected cells. Treatment with PMA (phorbol 12-myristate 13-acetate), a PKC activator, suppressed Trail-induced apoptosis in Jurkat T cells. The inhibition of apoptosis by PMA was abolished by pretreatment with Bis, a PKC inhibitor. Taken together, it was suggested that Bcl-2 over-expression and PMA activated PKC actively down-regulated the Trail-mediated apoptosis in Jurkat T cell.

Increased Protein Tyrosine Phosphorylation in Apoptotic Neural Cell Death Due to Microtubule Perturbations

The microtubule-perturbing drugs colchicine and taxol have been found to induce apoptosis in a CNS neuronal cell line. Apoptosis in drug-treated rat B103 neuroblastoma cells was evident in characteristic morphological changes, internucleosomal DNA fragmentation, and loss of nuclear content. Since colchicine and taxol have opposite actions on microtubule integrity, disruption of the active turnover of the microtubule network appears to be a crucial step for apoptosis to occur. It has been suggested that the basis for apoptosis by these drugs derives from their known block of the cell cycle at G₂/M, but this does not appear the sole reason as both colchicine and taxol were able to evoke high levels of apoptosis in cells differentiated by Bt₂cAMP or serum withdrawal. Further tests of cellular consequences of microtubule perturbation revealed a specific impact on signal transduction involving protein tyrosine phosphorylation. Immunoprecipitation with antibodies against tyrosine phosphorylated proteins showed a striking increase in the phosphorylation of a Triton-insoluble ~90 kDa protein, roughly concurrent with the onset of internucleosomal DNA fragmentation. Cycloheximide and genistein significantly reduced cell death and blocked appearance of the ~90 kDa tyrosine phosphorylated protein. Data suggest the hypothesis that signal transduction leading to apoptosis can be triggered by anomalous microtubule turnover and that the mechanism involves tyrosine phosphorylation of a ~90 kDa Triton-resistant protein.

Magnetic phagosome motion in J774A.1 macrophages: influence of cytoskeletal drugs

The role of the different cytoskeletal structures like microfilaments (MF), microtubuli (MT), and intermediate filaments (IF) in phagosome motion is unclear. These cytoskeletal units play an important role in macrophage function (migration, phagocytosis, phagosome transport). We investigated ferromagnetic phagosome motions by cell magnetometry. J774A.1 macrophages were incubated with 1.3-microm spherical magnetite particles for 24 h, after which more than 90% of the particles had been phagocytized. Phagosome motions can be caused either by the cell itself (relaxation) or by applying magnetic twisting forces, yielding cell stiffness and viscoelastic properties of the cytoskeleton. Apparent viscosity of the cytoplasm was non-Newtonian and showed a shear-rate-dependent power law behavior. Elastically stored energy does not force the magnetic phagosomes back to their initial orientation: 57% of the twisting shear was not recoverable. Cytoskeletal drugs, like Cytochalasin D (CyD, 2 - 4 microM), Colchicine (CoL, 10 microM), or Acrylamide (AcL, 40 mM) were added in order to disturb the different cytoskeletal structures. AcL disintegrates IF, but affected neither stochastic (relaxation) nor directed phagosome motions. CyD disrupts MF, resulting in a retarded stochastic phagosome motion (relative decay 0.53 +/- 0.01 after 5 min versus 0.34 +/- 0.01 in control), whereas phagosome twisting shows only a small response with a 9% increase of stiffness and a small reduction of recoverable strain. CoL depolymerizes the MT, inducing a moderately accelerated relaxation (relative decay 0.28 +/- 0.01 after 5 min) and a 10% increase of cell stiffness, where the pure viscous shear is increased and the viscoelastic recoil is inhibited by 40%. Combining the two drugs conserves both effects. After disintegrating either MF or MT, phagosome motion and cytoskeletal stiffness reflect the behavior of either MT or MF, respectively. The results verify that the dominant phagosome transport mechanism is MF-associated. MT depolymerization by CoL induces an activation of the F-actin synthesis, which may induce an accelerated relaxation and an increase of stiffness. Cell mechanical properties are not modulated by MF depolymerization, whereas MT depolymerization causes a loss of viscous resistance and a loss of cell elasticity. The mean energy for stochastic phagosome transport is 5*10(-18) Joules and corresponds to a force of 7 pN on a single 1.3-microm phagosome.

Supplementary report on experimental autumn crocus (Colchicum autumnale L.) poisoning in cattle: morphological evidence of apoptosis

Previously we reported that tissue destruction characterized by the presence of karyopyknotic, karyorrhectic and mitotically arrested cells was seen in alimentary epithelial cells and lymphocytes in the lymphoid and hemopoietic systems of cattle experimentally administered with autumn crocus (Colchicum autumnale L.). This report deals with the mechanism of acute cellular injury following experimental autumn crocus poisoning in cattle as demonstrated by the in situ DNA strand break analysis and electron microscopy. The analyses revealed that cellular injury caused by autumn crocus was closely associated with apoptosis.

Inhibition of protein synthesis by zinc: comparison between protein synthesis and RNA synthesis

Inhalation of zinc fumes may lead to the acute respiratory distress syndrome. The mechanisms of pulmonary zinc toxicity are not yet understood. Therefore we investigated zinc-dependent depression of protein and RNA synthesis in rat and human lung cell lines. 1. After exposure to 120 or 150 micromol/l zinc, RNA synthesis as assessed by uridine incorporation decreased by 60-70% between 0 and 2 h exposition in rat alveolar type II cells (L2 cells) and human fibroblast-like cells (11Lu and 16Lu cells), and by 90% between 0 and 4 h in carcinoma-derived cells (A549 cells). 2. After 2 h exposure, L2, 11Lu, and 16Lu cells were half-maximally inhibited by 50 micromol/l zinc, whereas A549 cells were more resistant with half-maximal inhibition at 100 micromol/zinc. 3. Protein and RNA synthesis was inhibited in parallel in L2, 11Lu, and A549 cells as indicated by simultaneous determination of uridine and amino acid incorporation. In 16Lu cells, the decline in protein synthesis preceded RNA synthesis inhibition. Pretreatment with RNA synthesis inhibitors (amanitin or actinomycin D) had no effect on time curve and intensity of RNA synthesis inhibition. Taken together, our results indicate that the suppression of RNA and protein synthesis likely are independent phenomena, due to direct zinc effects on these biosynthetic pathways.

Evidence that protein kinase Cepsilon mediates phorbol ester inhibition of calphostin C- and tumor necrosis factor-alpha-induced apoptosis in U937 histiocytic lymphoma cells

Protein kinase C (PKC) activators, such as the tumor-promoting phorbol esters, have been reported to protect several cell lines from apoptosis induced by a variety of agents. Recent evidence suggests that PKCepsilon is involved in protection of cardiac myocytes from hypoxia-induced cell death (Gray, M. O., Karliner, J. S., and Mochly-Rosen, D. (1997) J. Biol. Chem. 272, 30945-30951). We investigated the protective effects of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on U937 histiocytic lymphoma cells induced to undergo apoptosis by tumor necrosis factor-alpha (TNF-alpha) or by the specific PKC inhibitor calphostin C. U937 cells were transiently permeabilized with a peptide (epsilonV1-2) derived from the V1 region of PKCepsilon that has been reported to specifically block translocation of PKCepsilon. The epsilonV1-2 peptide blocked the inhibitory effect of TPA on both TNF-alpha- and calphostin C-induced apoptosis. A scrambled version of epsilonV1-2 and a peptide reported to inhibit PKCbeta translocation (betaC2-4) had no effect on the ability of TPA to inhibit apoptosis. These results suggest that PKCepsilon is required for the protective effect of TPA in TNF-alpha- and calphostin C-induced apoptosis. Furthermore, calphostin C reduced membrane-associated PKCepsilon activity and immunoreactivity, suggesting that PKCepsilon may play an important role in leukemic cell survival.

Effects on DNA integrity and apoptosis induction by a novel antitumor sesquiterpene drug, 6-hydroxymethylacylfulvene (HMAF, MGI 114)

6-Hydroxymethylacylfulvene (HMAF, MGI 114) is a new alkylating antitumor sesquiterpenoid with promising and often curative antitumor activity in vivo. This study examined the ability of the drug to damage cellular DNA, induce apoptosis, and affect the cell cycle of CEM human leukemia cells. No bifunctional lesions, interstrand DNA cross-links or DNA-protein cross-links were seen (by alkaline sedimentation and K+/SDS precipitation, respectively) when using up to 50 microM HMAF. The drug possibly formed some monoadducts, as DNA from drug-treated cells impeded primer extension by Taq polymerase, although only partial inhibition was seen even at 200 microM HMAF. HMAF also induced secondary lesions in cellular DNA, single-strand breaks that were detectable (by nucleoid sedimentation and alkaline sucrose gradient analysis) after a 4-hr treatment at HMAF levels as low as 2 microM, comparable to the growth inhibition IC50 value (1.7 microM). A post-treatment incubation of cells in drug-free medium generated substantial amounts of DNA double-stranded fragments of several kbp, suggesting apoptotic fragmentation (>30% of total DNA following treatment with 20 microM HMAF and a 17-hr post-treatment incubation). Chromatin condensation (by ultrastructural analysis) and induction of sub-G1 particles and apoptotic strand breakage (by multiparametric flow cytometry) confirmed induction of apoptosis by HMAF. HMAF preferentially inhibited DNA synthesis (IC50 approximately 2 microM), which is consistent with an S phase block, observed by cell cycle analysis. The pattern of apoptotic DNA fragmentation, inhibition of DNA synthesis, and blockage in the S phase suggests that these events play a role in the antiproliferative activity of HMAF.

Apoptosis and proliferative activity of non-Hodgkin's lymphomas: comparison with expression of bcl-2, p53 and c-myc proteins

In order to clarify the role of spontaneous apoptosis of non-Hodgkin's lymphomas in the growth regulation system, apoptotic indices (AI) assessed by DNA nick end-labeling and proliferative activity, estimated in terms of KI-67 labeling indices (KI) and mitotic indices (MI), were compared. In addition, expression of bcl-2, p53 and c-myc was also examined in relation to these indicators. For this study, 103 lymphoma cases were used, comprising 72 of B cell and 31 of T cell origin (42 nodal and 62 extranodal). AI, KI and MI were significantly increased in line with bcl-2 negativity and p53 positivity, and there was no relation to the T, B cell classification or expression of c-myc. These indicators positively correlated overall. Positive correlation was stricter in groups believed to represent a good prognostic predictive factor, such as B cell origin, bcl-2(+), p53(-) and c-myc(-). Significant cross-correlation was noted only between bcl-2 versus T, B cell classification. However, no inverse correlation between bcl-2 and p53 was evident. These results suggest, in non-Hodgkin's lymphomas, that apoptosis plays an important role together with proliferative activity in counter-balancing tumor volume, and is strictly linked to bcl-2 expression, less so to p53 expression, but independent of T, B cell classification and c-myc expression. Apoptotic indices may be a predictive indicator for prognosis similar to proliferative activity.

Apoptosis of colon cancers assessed by in situ DNA nick end-labeling method

Apoptosis in colon cancers was investigated using in situ DNA nick end-labeling. Seventy-six colon cancer cases were divided according to histologically defined malignant grading, degree of invasion and other pathologic indicators. The apoptotic labeling index (ALI) was highest in cases with invasion limited to the submucosa, the difference as compared to other stages being statistically significant, while no correlation was noted between ALI and histological type. ALI significantly decreased with lymph node involvement of cancers. In contrast, there appeared to be no link with vessel invasion. ALI was significantly higher in lesions smaller than 2 cm in diameter. These results indicate that apoptosis in colon cancers is more frequent at a relatively early stage when the lesions are small, and suggest that the apoptotic phenomenon may play some role in regulating the size and progression of such tumors.

Apoptotic bodies in prostatic intraepithelial neoplasia and prostatic adenocarcinoma following total androgen ablation

The frequency and location of apoptotic bodies (AB) were evaluated in hematoxylin- and eosin-stained sections of 12 radical prostatectomies from patients with prostatic adenocarcinoma pre-treated for 3 months with total androgen ablation. Results were compared with an untreated age-, morphology- and stage-matched control group. Treated prostates showed involutional changes, with cytoplasmic vacuolization and chromatin changes ranging from mild to severe condensation, similar to that observed in apoptosis. In treated benign prostatic epithelium, the mean number of AB was 1.64% (standard error (SE), 0.19%), 6.3 times greater than in the untreated group (mean, 0.26%; SE, 0.03%). AB were more frequent in the basal cell layer than in the lumenal cell layer, whereas in the untreated group, AB were almost exclusively found in the basal cell layer. In treated prostatic intraepithelial neoplasia (PIN present in 10 cases), the mean number of AB was 1.74% (SE, 0.04%), which was 2.56 and 2.32 times greater than in untreated low grade PIN (mean, 0.68%; SE, 0.15%) and high grade PIN (mean, 0.75%; SE, 0.11%), respectively. In treated and untreated PIN, the number of AB was greatest in the basal cell layer, less in the intermediate cell layer and lowest in the cell layer bordering the lumen. The mean number of AB in the 12 treated cancers was 1.35 times greater than in untreated cancers (1.80% [SE, 0.12%] versus 1.33% [SE, 0.32%], respectively). The number of AB in treated cases of the acinar pattern of cancer (present in 7 cancer cases) was 1.78 times greater than in untreated cases, and in treated cases of the cribriform pattern of cancer (present in four cases), the mean number of AB was 1.39 times greater than in untreated cases. The number of AB was greatest in the outermost cell layer, with progressive decrease in layers closer to the lumen. In the one treated case with solid/trabecular pattern of cancer, the number of AB was 1.08 times greater than in untreated cases. The gland lumina was rich in macrophages, sloughed secretory cells with degenerative features and AB. The number of AB in the lumina increased from normal epithelium through PIN to cancer, and was greater in treated cases than in untreated cases.

Expression of full-length human procathepsin L cDNA in Escherichia coli and refolding of the expression product

From human embrional lung fibroblasts mRNA was obtained and converted to cDNA. The procathepsin L coding region was amplified by PCR, inserted into pALTER and, after checking the nucleotide sequence, transferred into pET81F1+. Procathepsin L was expressed by induction of recombinant E. coli strain BL21[DE3](pLysS) with IPTG and was found to be deposited into inclusion bodies. These were isolated and solubilized in guanidinium hydrochloride. The soluble proteins were sulphonated and procathepsin L was obtained after gel filtration. Purified proenzyme was refolded by dialysis and autoactivated into a form of the expected size and enzymatic activity against a fluorogenic substrate.

Defective expression of hematopoietic cell protein tyrosine phosphatase (HCP) in lymphoid cells blocks Fas-mediated apoptosis

Protein tyrosine dephosphorylation after Fas cross-linking occurred in Fas apoptosis-sensitive CEM-6 cells but not in Fas apoptosis-resistant MOLT-4 cells, and apoptosis in the CEM-6 cells could be inhibited by the protein tyrosine phosphatase inhibitor, pervanadate. The time course and level of dephosphorylation were correlated with increased hematopoietic cell protein tyrosine phosphatase (HCP) activity, but not with the activity of two other tyrosine phosphatases. The level of expression of HCP was correlated with Fas apoptosis function in eleven human and murine Fas-positive lymphoid cell lines. Expression of recombinant HCP in the MOLT-4 cell line converted this Fas apoptosis-resistant cell line to Fas apoptosis sensitive. HCP-mutant mev/mev mice exhibited increased expression of Fas but decreased Fas-mediated apoptosis function in lymphoid organs after anti-mouse Fas antibody treatment in vivo. Thus, HCP-mediated protein dephosphorylation is involved in the delivery of the Fas apoptosis signal in lymphoid cells.

Pathologic analyses of non-overt necrotizing type Kikuchi and Fujimoto's disease

Twenty-eight cases of non-overt necrotizing type Kikuchi-Fujimoto disease (KF disease, histiocytic necrotizing lymphadenitis) were investigated clinicopathologically, immunohistochemically and electron microscopically in order to analyze the nature of this disease. In addition, investigations to detect the presence of Epstein-Barr virus (EBV) using the polymerase chain reaction (PCR) and in situ hybridization (ISH) were also performed as a high incidence of positive serum immunoreactivity to EBV had been revealed in the cases examined. The clinical features were an equal male to female ratio, mean age of 26 years, mild leukopenia and about 40% association with fever over 38 degrees C. The major particular pathologic features were: (i) varying amounts of nuclear debris in the pathologic areas, identified as apoptosis by electron microscopy; (ii) presence of medium to large sized transformed lymphocytes (immunoblasts), a very small number of them positive for both UCHL1 and L26, and plasmacytoid cells, some of them positive for UCHL1; and (iii) characteristically shaped histiocytes predominant in the pathologic areas, with irregular nuclei and strongly positive for anti-lysozyme and anti-alpha 1-antitrypsin antibodies. Investigations with PCR and ISH revealed a complete absence of EBV in these cases despite excellent results for positive controls. It was therefore considered that EBV was not a causative virus for KF disease.

Occurrence of cell death (apoptosis) in prostatic intra-epithelial neoplasia

The aim of our study was to assess the frequency and location of apoptotic bodies (ABs) in haematoxylin and eosin-stained sections of prostatic intraepithelial neoplasia (PIN) and then to compare the patterns with those in benign prostatic hyperplasia (BPH) and prostatic invasive adenocarcinoma (PAC). ABs were identified in all epithelial cell layers of the ducts, acini and tumour islands, as well as in the lumina contained in such structures. In the epithelial cell layers, ABs were found in general in the intercellular space and occasionally in the cytoplasm of epithelial cells. The frequency of ABs increased from BPH through PIN up to PAC. The proportions of ABs in PIN lesions of low grade (PINlow) and high grade (PINhigh) were greater than in BPH, the values decreasing from the nuclei in the basal position towards those in the luminal layer. In PINlow, the mean category values were 0.85% (standard error, SE, 0.311%) in the basal, 0.623% (SE 0.065%) in the intermediate and 0.474% (SE 0.138%) in the luminal position. In PINhigh, the mean category values were 1.006% (SE 0.16%) in the basal position, 0.713% (SE 0.182%) in the intermediate and 0.618% (SE 0.172%) in the luminal position. The proportions of ABs in adenocarcinoma with cribriform pattern decreased from the basal towards the luminal layer, as for PIN: 1.806% (SE 0.346%) in the basal position, 1.15% (SE 0.172%) in the intermediate and 0.886% (SE 0.137%) in the luminal position. In the solid/trabecular adenocarcinomas, the mean category value in the cell layer adjacent to the stroma was 2.154% (SE 0.203%), whereas in the other cell layers it was 2.052% (SE 0.239%). In small and large acinar adenocarcinomas, the proportions of positive nuclei were 1.022% (SE 0.1%) and 0.922% (SE 0.163%), respectively. The evaluation of the frequency and location of ABs gives accurate information on cell death in PIN in comparison with BPH and PAC.