PubMed Health⌕ Search

Biomedical subjects

E Sikora

Publications and source records attributed to E Sikora.

At least 19 recordsLinked to original sources
PubMed2001

Effect of glutathione depletion on caspase-3 independent apoptosis pathway induced by curcumin in Jurkat cells.

Curcumin, a yellow pigment from Curcuma longa, exhibits anti-inflammatory, antitumor, and antioxidative properties. Although its precise mode of action has not been elucidated so far, numerous studies have shown that curcumin may induce apoptosis in normal and cancer cells. Previously, we showed that in Jurkat cells curcumin induced nontypical apoptosis-like pathway, which was independent of mitochondria and caspase-3. Now we show that the inhibition of caspase-3 by curcumin, which is accompanied by attenuation of internucleosomal DNA fragmentation, may be due to elevation of glutathione, which increased in curcumin-treated cells to 130% of control. We have demonstrated that glutathione depletion does not itself induce apoptosis in Jurkat cells; though, it can release cytochrome c from mitochondria and caspase-3 from inhibition by curcumin, as shown by Western blot. The level of Bcl-2 protein was not affected by glutathione depletion even upon curcumin treatment. Altogether, our results show that in Jurkat cells curcumin prevents glutathione decrease, thus protecting cells against caspase-3 activation and oligonucleosomal DNA fragmentation. On the other hand, it induces nonclassical apoptosis via a still-unrecognized mechanism, which leads to chromatin degradation and high-molecular-weight DNA fragmentation.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Pantothenic acid protects jurkat cells against ultraviolet light-induced apoptosis.

Human leukemic T lymphocytes (Jurkat cells) were induced to undergo apoptosis by brief irradiation with ultraviolet C light (254 nm). This was accompanied by accumulation of lipid peroxidation products in the form of conjugated dienes, a decrease of total glutathione content, and a shift of its redox state towards the oxidized form. Preincubation of the cells with 1 mM pantothenate resulted in a significant elevation of total glutathione content of the cells, reaching its maximum level, 160% of the control, after 3 h. Similar increase was observed after preincubation with 5 mM N-acetylcysteine, a known precursor of glutathione. Both pantothenic acid and N-acetylcysteine alleviated the ultraviolet-induced decrease of glutathione content, diminished lipid peroxidation, and partly protected the cells against apoptosis produced by ultraviolet irradiation.

Acetylcysteine↗
PubMed2000

Effect of curcumin on the apoptosis of rodent and human nonproliferating and proliferating lymphoid cells.

Curcumin, a major active component of turmeric, has been recognized as an anticarcinogenic agent because of its propensity to induce apoptosis in vivo and in vitro. Previously, we showed that curcumin protects cells against oligonucleosomal DNA fragmentation and induces a novel apoptosis-like pathway in Jurkat cells (Piwocka et al. Exp Cell Res 249, 299-307, 1999). Here, we have studied the ability of curcumin to induce cell death in other human and rodent transformed as well as normal cells. Normal cells were quiescent or stimulated to proliferate. We showed that 50 microM pigment is able to induce cell death in all studied cells, but cell death symptoms varied for different cells. All the cells died as assessed by the TdT-mediated UTP nick end labeling method or trypan blue exclusion test. No one type of cells showed oligonucleosomal DNA fragmentation (DNA "ladder") due to curcumin action, although in HL-60 cells, we were able to observe sub-G1 formation and caspase-3 activation. Together, these data showed that curcumin induces cell death in all tested cells that can be classified as apoptosis-like, and only in HL-60 cells can it be recognized as classical apoptosis.

Adult↗
PubMed2000

Proliferation and apoptosis of human T cells during replicative senescence--a critical approach.

Normal human T lymphocytes growing in culture undergo replicative senescence. Previously, we have shown that in our conditions polyclonal T cells cease proliferation after about three weeks (Radziszewska et al., 1999, Cell Biol. Int. 23, 97-103). Now we present results of a more detailed analysis of in vitro growth as well as phenotypic changes of T cells. Cell cycle analysis showed that about 20% of cells were in the S phase until the 17th day of culture (young cells). The highest number of mitotic cells (phase G2/M; 10%) was observed during the first week of culture. All not dividing senescent cells were stopped in the G1 phase (after the 30th day of culture). The sub-G1 fraction which represents apoptotic cells did not exceed 8% during the whole period until the 30th day of culture. During in vitro T-cell growth, a rather rapid selection to CD3+ CD8+ cells occurs. In the presenescent (between the 17th and 30th day) and senescent populations the majority of cells (above 90%) were CD8 positive. We also have checked the expression of alpha-chain interleukin-2 (IL-2) receptor (CD25). In young and presenescent cells about one third of cells was CD25 positive, but only 15% in the pool of senescent cells. Immunoblotting analysis of p16 protein recognized previously as a marker of senescent T cells, showed its highest and transient expression in presenescent cells. A critical review of the polyclonal T cell replicative senescence model is presented.

Adult↗
PubMed2000

Effect of aging on UVC-induced apoptosis of rat splenocytes.

UVC-induced apoptotic symptoms such as morphological changes, DNA fragmentation, Bcl-2 and Bax protein expression were examined in primary splenocyte cultures from young (3 months) and old (24 months) rats. The activities of AP-1 and CRE transcription factors in UVC-irradiated splenocytes were also assessed. At 24 h after UVC irradiation 40% of cells derived from young rats were found to be apoptotic, which was twice as much as in splenocytes from old rats. Apoptosis in cells from old rats did not give typical symptoms like a "DNA ladder" and Bcl-2 protein downregulation, in contrast to splenocytes from young rats. No AP-1 transcription factor activity was found in UVC-irradiated splenocytes from old animals and only a trace activity in splenocytes from young animals. This indicates that, UVC-induced apoptosis in rat splenocytes is practically AP-1 independent and that cells from old rats are less sensitive to UVC irradiation than splenocytes from young rats.

Aging↗
PubMed1999

A novel apoptosis-like pathway, independent of mitochondria and caspases, induced by curcumin in human lymphoblastoid T (Jurkat) cells.

We have shown previously [E. Sikora, A. Bielak-Zmijewska, K. Piwocka, J. Skierski, and E. Radziszewska (1997) Biochem. Pharmacol. 54, 899-907] that curcumin prevents formation of oligonucleosomal DNA fragmentation in rat thymocytes and human leukemic T lymphocytes (Jurkat cells) induced to undergo apoptosis. In this paper we show that 50 microM curcumin by itself induces cell death in Jurkat cells, but its symptoms differ from those observed after a short ultraviolet (uv) irradiation. Ultraviolet-irradiated Jurkat cells displayed typical symptoms of apoptosis: morphological changes, internucleosomal and high-molecular-weight DNA fragmentation, formation of sub-G1 fractions in DNA content frequency histograms, and dissipation of the mitochondrial transmembrane electric potential (Delta psi). In contrast, curcumin-treated Jurkat cells exhibited DNA splitting into high-, but not low-, molecular-weight fragments. These cells retained their high mitochondrial Delta psi, and the content of Ca2+ in endoplasmic reticulum stores remained at the level typical for untreated cells. The frequency of opening of the mitochondrial permeability transition pores in curcumin-treated cells was decreased compared to the controls, whereas uv irradiation made these pores completely open. Curcumin did not produce any change in the activity of caspase-3, whereas uv irradiation considerably activated this protease. The morphology of curcumin-treated cells displayed chromatin condensation, which was insensitive to the caspase inhibitor z-VAD-fmk, but no formation of typical apoptotic bodies, as was the case after uv irradiation. In contrast to uv-irradiated cells, curcumin-treated Jurkat cells considerably increased the level of Bcl-2. It is concluded that the programmed cell death induced by curcumin in Jurkat cells differs from "classical" by the lack of mitochondrial depolarization and of the involvement of caspases.

Antineoplastic Agents↗
PubMed1999

UVC-induced cell death of IL-2-dependent human lymphocytes.

We compared the in vitro propensity of human IL-2-dependent lymphocytes (young proliferating and senescent non-proliferating), and resting peripheral blood lymphocytes (PBLs) to undergo UVC-induced apoptosis. The activities of AP-1 (activator protein-1), CRE (cAMP response element) and OCT-1 (octamer-1) transcription factors in all lymphocytes were also assessed. At 24 h after UVC treatment, half of young proliferating T lymphocytes and about a quarter of PBLs and senescent non-proliferating cells were apoptotic, as shown by flow cytometry. However, only in young lymphocytes were both typical DNA 'ladder' and Bcl-2 downregulation evident. The AP-1 transcription factor was activated by UVC in IL-2-dependent young and senescent, but not resting lymphocytes. Taken together, the data show different propensities of resting, proliferating and senescent human lymphocytes to undergo UVC-induced apoptosis and AP-1 activation.

Adult↗
PubMed1999

Activation of a low pH-dependent nuclease by apoptotic agents.

Intracellular acidification caused by agents such as UV(C), etoposide or ceramide accompanies the progression of apoptosis. It is suggested that cellular acidosis may set favorable conditions for a dormant, low pH-dependent (acidic) nuclease, which could be involved in intranucleosomal genome degradation, a hallmark of programmed cell death. Here we show that exposure of HL-60 cells to acidotic/apoptotic agents results in the several-fold activation of a novel low pH-dependent (acidic) nuclease activity, as revealed by zymography. Its activity, which resides in nuclei, is associated with four polypeptides with apparent Mr of 56, 48, 45 and 40 kDa. Treatment of HeLa cells with UV(C) or ceramide causes also the up-regulation of an acidic nuclease activity which is represented by 70 and 62 kDa polypeptides. These observations suggest that acidic nuclease activation can be induced by the same apoptotic agents in different cell types. In HL-60 cells, acidic nuclease up-regulation triggered by acidotic agents follows the induction of AP-1 transcription factor active complexes and accompanies the progression of apoptosis. Inhibition of AP-1 factor activity caused by either anti-caspase/anti-acidotic agent Zn2+ or curcumin, an inhibitor of AP-1 binding to DNA and c-jun synthesis, protects cells from genome destruction. Acidic nuclease activation, however, is only partially inhibited by these factors. We propose that (i) the up-regulation of an acidic nuclease activity is governed by a regulatory pathway different from that responsible for AP-1 factor induction, caspases activation and intracellular acidification, and (ii) activation of an acidic nuclease does not cause any deleterious effects when AP-1 transcription factor induction, caspases activation and intracellular acidification are down-regulated. Thus, the acidic nuclease up-regulation alone is not a sufficient prerequisite for apoptosis.

Apoptosis↗
PubMed1998

Glutathione-independent mechanism of apoptosis inhibition by curcumin in rat thymocytes.

Curcumin (CUR) is a natural yellow dye with antioxidant and scavenging properties present in Curcuma species. It is widely used as an anti-inflammatory, anti-mutagenic and chemopreventive agent. In addition to its inhibitory effect on proliferation, CUR has recently been shown to block dexamethasone-induced programmed cell death (apoptosis) of rat thymocytes. Because cellular thiols seem to play a role in redox regulation of apoptosis, the mechanism of the anti-apoptotic effect of CUR was studied by examining the levels of glutathione and acid-soluble sulfhydryl groups. CUR was shown to prevent the glutathione loss occurring in dexamethasone-treated thymocytes, enhancing intracellular glutathione content at 8 hr to 192% of that of nontreated cells. A 60% increase in acid-soluble sulfhydryl groups was also observed. In the presence of L-buthionine S,R-sulfoximine (BSO, an inhibitor of glutathione synthesis), intracellular glutathione content of thymocytes treated with dexamethasone and CUR fell to 31% and that of the acid-soluble sulfhydryl groups to 23% of control after 8 hr. Unexpectedly, the electrophoretic and flow cytometric studies of DNA fragmentation demonstrated that apoptosis did not occur even after 20 hr of incubation with buthionine S,R-sulfoximine and dexamethasone, while control thymocytes and the cells treated only with buthionine S,R-sulfoximine showed DNA fragmentation at a level corresponding to spontaneous apoptosis. These results show that CUR treatment elevated the concentrations of glutathione and nonprotein sulfhydryl groups, thus preventing their decrease in apoptotic thymocytes. Coadministration of L-buthionine S,R-sulfoximine and CUR did not affect the anti-apoptotic effect of CUR suggesting a glutathione-independent mechanism of cell protection.

Animals↗
PubMed1998

Apoptosis-like, reversible changes in plasma membrane asymmetry and permeability, and transient modifications in mitochondrial membrane potential induced by curcumin in rat thymocytes.

Curcumin (diferuoylmethane) is a natural compound with anticarcinogenic activities which is able to exert either proapoptotic or antiapoptotic effects in different cell types. This paper focuses on the sequence and extent of primary events induced by curcumin, in comparison with those occurring during dexamethasone-induced apoptosis in rat thymocytes. It also presents annexin VI-FITC as a new probe for studying membrane asymmetry. Curcumin readily penetrates into the cytoplasm, and is able to accumulate in membranous structures such as plasma membrane, endoplasmic reticulum and nuclear envelope. Curcumin-treated cells exhibit typical features of apoptotic cell death, including shrinkage, transient phosphatidylserine exposure, increased membrane permeability and decrease in mitochondrial membrane potential. However, nuclei morphology, DNA fragmentation, the extent and time-course of membrane changes are different from those observed during dexamethasone-induced apoptosis, suggesting that, despite many similarities, the mode of action and the events triggered by curcumin are different from those occurring during typical apoptosis.

Animals↗
PubMed1998

Growth properties and growth factor responsiveness in skin fibroblasts from centenarians.

Human fibroblast cultures, which have a finite replicative lifespan in vitro, are the most widely used model for the study of senescence at the cellular level. An inverse relationship between replicative capability and donor age has been reported in human fibroblast strains. We studied the growth capacity of fibroblast primary cultures derived from people whose lifespan was as closer as possible to the expected maximum human lifespan, i.e. people over one hundred. Our data suggest that outgrowth of fibroblasts from biopsies, growth kinetics at different population doubling levels, capability to respond to a classical mitogenic stimulus (such as 20% serum) and a variety of growth factors, were remarkably similar in fibroblasts from centenarians and young controls. On the whole, our data challenge the tenet of a simple and strict relationship between in vivo aging and in vitro proliferative capability of human fibroblasts, at least at the individual level.

Adolescent↗
PubMed1998

Collateral projections of trigeminal sensory neurons to both cerebellar paramedian lobules in the rabbit: demonstration by fluorescent double labeling study.

Neurons in the trigeminal sensory nuclei (TSN) were indicated to project simultaneously to the cerebellar paramedian lobule (PML) of both sides by way of axon collaterals in the rabbit. Injections of Fast Blue and Diamidino Yellow made in twelve rabbits into the regions of the left and right PML cortex, respectively, resulted in retrograde double labeling of neurons in the principal trigeminal (Vp) and spinal trigeminal nuclei including subnucleus oralis (Vo), and rostral (Vir) and caudal (Vic) subnucleus interpolaris. Sparse labeling was seen among the root fibers of the facial nerve immediately adjacent to Vp. The data indicated that out of the total population of ipsilateral and contralateral single labeled neurons in TSN subdivisions, double labeled neurons constituted about 11% in Vo, 2% in Vp and Vir, and 1% in Vic. Thus, it seems that out of TSN neurons sending collateral projections to PML of both hemispheres, those in Vo project more frequently than those in Vp, Vir and Vic. The homotopic (corresponding) middle (c and d) PML sublobules receive collateral projections from neurons of all these TSN subdivisions, whereas the caudal (a and b) and rostral (e and f) sublobules seem to be targets of the projection from Vp and Vir. The findings suggest that some TSN neurons may exert simultaneous bilateral modulatory influences upon the regions in various sublobules of both PML.

Animals↗
PubMed1998

Axonal ramification of neurones in the nuclei raphe pallidus and obscurus projecting to the cerebellar paramedian lobule. A fluorescent double labelling study in the rabbit.

As a part of a study concerning the raphe nuclei-cerebellar cortex projection the fluorescent retrograde double labelling technique was employed to investigate the location of raphe neurones projecting to the paramedian lobule (PML) of both sides by axonal collaterals in the rabbit. Diamidino Yellow and Fast Blue injections into the right and left PML, respectively, resulted in labelling of a limited number of these neurones exclusively within the raphe pallidus and raphe obscurus nuclei.

Amidines↗
PubMed1997

Inhibition of proliferation and apoptosis of human and rat T lymphocytes by curcumin, a curry pigment.

Curcumin (diferuoylmethane), the yellow pigment in the rhizome of tumeric (Curcuma longa), an ingredient of curry spice, is known to exhibit a variety of pharmacological effects including antitumor, antiinflammatory, and antiinfectious activities. Although its precise mode of action remains elusive, curcumin has been shown to suppress the activity of the AP-1 transcription factor in cells stimulated to proliferate. In this study, we observed that curcumin (50 microM) inhibited proliferation of rat thymocytes stimulated with concanavalin A (Con A) as well as that of human Jurkat lymphoblastoid cells in the logarithmic growth phase. The pigment also inhibited apoptosis in dexamethasone-treated rat thymocytes and in UV-irradiated Jurkat cells as judged by DNA ladder formation, cellular morphological changes, and flow cytometry analysis. The inhibition of apoptosis by curcumin in rat thymocytes was accompanied by partial suppression of AP-1 activity. Complete suppression of AP-1 activity was observed in Con A-treated, proliferating thymocytes. The capacity of curcumin to inhibit both cell growth and death strongly implies that these two biological processes share a common pathway at some point and that curcumin affects a common step, presumably involving a modulation of the AP-1 transcription factor.

Animals↗
PubMed1996

c-fos/c-jun expression and AP-1 activation in skin fibroblasts from centenarians.

In vitro replicative senescence is characterized by an irreversible growth arrest due to the inability of the cell to induce some key regulators of cell cycle progression, such as c-fos and AP-1, in response to mitogenic stimuli. In vitro replicative senescence and in vivo aging have been assumed to be two related phenomena, likely controlled by overlapping or interacting genes. As a corollary, fibroblasts from centenarians, which have undergone a long process of senescence in vivo should have very limited proliferative capability. On the contrary, in a previous work we found that fibroblasts from centenarians exhibited the same capacity to respond to different mitogenic stimuli as fibroblasts from young donors. Here we provide evidences that the well preserved proliferative response is likely due to the fact that some pivotal regulators- c-fos, c-jun and AP-1-are still fully inducible, despite a long process of in vivo senescence. Our data therefore suggest that in vivo and in vitro aging are separate phenomena whose possible relationships, if any, have to be ascertained very carefully.

Adolescent↗