In vitro cytotoxicity of glyco-S-nitrosothiols. a novel class of nitric oxide donors.

The cytotoxicities of the nitric oxide (NO) donors, S-nitroso-N-acetylpencillamine (SNAP) and three glyco-SNAPs, glucose-1-SNAP, glucose-2-SNAP, and fructose-1-SNAP, towards the human gingival epithelioid S-G cell line and three human carcinoma cell lines derived from tissues of the oral cavity were compared using the neutral red (NR) assay. In general, the glucose-SNAPs were more cytotoxic than SNAP, which, in turn, was more cytotoxic than fructose-1-SNAP. Further studies focused on the response of S-G cells to glucose-2-SNAP. The cytotoxicity of glucose-2-SNAP was attributed to NO, as glucose-2-SNAP (t1/2=20 h at 28 degrees C) aged for 4 days was nontoxic, toxicity was eliminated in the presence of hydroxocobalamin, a specific NO scavenger, and toxicity was not noted with glucose-2-AP (the parent compound used to construct glucose-2-SNAP). Exposure of cells to glucose-2-SNAP resulted in a lessening of the intracellular level of glutathione and cells pretreated with the glutathione-depleter, 1,3-bis-(chloroethyl)-1-nitrosourea, were more sensitive to a subsequent challenge with glucose-2-SNAP. Cytotoxicity of glucose-2-SNAP was lessened upon coexposure with the antioxidants, myricetin, N-acetyl-L-cysteine, and L-ascorbic acid. S-G cells exposed to glucose-2-SNAP exhibited bi- and multinucleation. Death of S-G cells exposed to glucose-2-SNAP apparently occurred by apoptosis, as demonstrated with fluorescence microscopy by the appearance of brightly stained, hypercondensed chromatin in spherical cells and of membrane blebbing and by the DNA-ladder of oligonucleosome-length fragments noted with gel electrophoresis. In comparison with other classes of NO donors the sequence of toxicity towards S-G cells was S-nitrosoglutathione>glucose-SNAPs>SNAP, sodium nitroprusside>spermine NONOate>DPTA NONOate>DETA NONOate>fructose-1-SNAP>SIN-1.     

In vitro cytotoxicity of the nitric oxide donor, S-nitroso-N-acetyl-penicillamine, towards cells from human oral tissue.

The cytotoxicity of the nitric oxide donor, S-nitroso-N-acetyl-penicillamine (SNAP), towards cultured human cells from oral tissue was evaluated. The toxicity of SNAP to Smulow-Glickman gingival epithelial cells was correlated with the liberation of nitric oxide, as N-acetyl-D,L-penicillamine, the SNAP metabolites, N-acetyl-D,L-penicillamine disulfide and nitrite, and preincubated (denitrosylated) SNAP did not affect viability. Comparing equimolar concentrations of various nitric oxide donors, cytotoxicity appeared to be inversely related to the relative stability (i.e., half-life) of the test compound; the sequence of cytotoxicity for a 4 hr exposure was S-nitrosoglutathione>spermine NONOate> SNAP>DPTA NONOate>DETA NONOate. Intracellular reduced glutathione (GSH) was lowered in S-G cells exposed to SNAP. Pretreatment of the cells with the GSH depleter, 1,3-bis-(chloroethyl)-1-nitrosourea (BCNU), enhanced the toxicity of SNAP Similar findings of enhanced sensitivity to SNAP were noted with gingival fibroblasts and periodontal ligament cells pretreated with BCNU. The toxicity of SNAP towards the gingival epithelial cells was decreased by cotreatment with the antioxidants, N-acetyl-L-cysteine, L-ascorbic acid, and (+)-catechin. Cells exposed to SNAP exhibited nuclear aberrations, including multilobed nuclei and multinucleation. SNAP-induced cell death was apparently by apoptosis, as noted by fluorescence microscopy and DNA agarose gel electrophoresis.     

In vitro response of human gingival epithelioid S-G cells to minocycline.

Minocycline, a broad-spectrum antibiotic used in the treatment of acne and periodontal disease and to control inflammatory diseases such as rheumatoid arthritis, has recently been shown to induce a spectrum of adverse health effects. In the light of these contradictory data, this research was directed to provide basic information on the toxicology of minocycline, using in vitro cell culture models, and to evaluate its efficacy in periodontal therapies, particularly for wound healing. The human gingival epithelioid S-G cell line was used as the bioindicator. The greater toxicity of minocycline over doxycycline and tetracycline, related antimicrobial agents, probably correlated with its higher lipophilicity. The cytotoxicity of minocycline was unaffected by an S9 hepatic microsomal fraction, indicating that it is a direct-acting, rather than a metabolism-mediated, cytotoxicant. In comparative toxicity studies, much variation in the degree of sensitivity to minocycline was noted for different cell types. No correlation in the extent of sensitivity to minocycline and the physiologic state of the bioindicator cell (normal, transformed or malignant) was noted. The toxicity of minocycline to the S-G cells was dependent on its concentration and length of exposure. For a continuous 3-day exposure of the S-G cells to minocycline, the midpoint cytotoxicity (or, NR(50)) value, as quantified in the neutral red (NR) assay, was 204 microg/ml on day 1, 84 microg/ml on day 2, and 59 microg/ml on day 3. For a 1-h exposure of the S-G cells in phosphate buffered saline (PBS), the NR(50) value was 780 microg/ml minocycline. Although a 1-h exposure in PBS to 200 microg/ml minocycline exerted some toxicity, the S-G cells recovered on exposure to growth medium; irreversible, progressive damage occurred at 400 microg/ml minocycline and greater. Minocycline, at 50 microg/ml, enhanced attachment of the S-G cells to a gelatin-coated surface and cell migration towards an immobilized fibronectin gradient, both biologic parameters important in periodontal wound healing. Minocycline generally had little or no effect on production of the pro-inflammatory cytokines, interleukin-6 (IL-6) and interleukin-8 (IL-8), by non-activated S-G cells, the exception being stimulation of IL-6 at 48 h. IL-1beta, however, greatly stimulated IL-6 and IL-8 production, which was further increased by concurrent exposure to minocycline. This suggested that minocycline may enhance the ability of gingival epithelial cells to participate in the early, inflammatory phase of periodontal wound healing. The limitation of minocycline efficacy to a rather narrow window of concentration, centering about 50 microg/ml, and primarily for short-term exposures may possibly explain, in part, the contradictory clinical data on the health effects of this drug.     

Cytotoxicity of Sanguinarine Chloride to Cultured Human Cells from Oral Tissue

Abstract: The in vitro cytotoxicity of sanguinarine chloride, a dental product used in the treatment of gingivitis and plaque, was compared using cell lines and primary cells from oral human tissues. For the established cell lines, sanguinarine chloride exhibited similar potencies to S-G gingival epithelial cells and to KB carcinoma cells, whereas HGF-1 gingival fibroblasts were more tolerant. However, a gingival primary cell culture was more sensitive to sanguinarine chloride than were the established cell lines. Detailed studies were performed with the S-G cells. The 24-hr midpoint (NR₅₀) cytotoxicity value towards the S-G cells was 7.6 uM, based on the neutral red cytotoxicity assay; vacuolization and multinucleation were noted. When exposed to sanguinarine chloride for 3 days, a lag in growth kinetics was first observed at 1.7 μM. Damage to the integrity of the plasma membrane was evident, as leakage of lactic acid dehydrogenase occurred during a 3 hr exposure to sanguinarine chloride at 0.1275 mM and greater. The cytotoxicity of sanguinarine chloride to the S-G cells was lessened in the presence of an S9 hepatic microsomal fraction from Aroclor-induced rats or by including fetal bovine serum (15%) in the exposure medium. Progressively increasing the pH from 6.0 to 7.8 enhanced the potency of sanguinarine chloride, presumably due to the enhanced uptake of the lipophilic alkanolamine form, as compared to that of the cationic iminium form.     

In vitro Cytotoxicity of the Nitric Oxide Donor,S-Nitroso-N-acetyl-peraciUamine,towards Cells from Human Oral Tissue

Abstract: The cytotoxicity of the nitric oxide donor, S-nitroso-N-acetyl-penicillamine (SNAP), towards cultured human cells from oral tissue was evaluated. The toxicity of SNAP to Smulow-Glickman gingival epithelial cells was correlated with the liberation of nitric oxide, as N-acetyl-D, L-penicilIamine, the SNAP metabolites, N-acetyl-D, L-penicillamine disulfide and nitrite, and preincubated (denilrosylated) SNAP did not affect viability. Comparing equimolar concentrations of various nitric oxide donors, cytotoxicity appeared to be inversely related to the relative stability (i.e., half-life) of the test compound; the sequence of cytotoxicity for a 4 hr exposure was S-nitrosoglutathione>>spermine NONOate> SNAP>DPTA NONOate>>DETA NONOate. Intracellular reduced glutathione (GSH) was lowered in S-G cells exposed to SNAP. Pretreatment of the cells with the GSH depleter, 1, 3-bis-(chloroethyl)-1-nitrosourea (BCNU), enhanced the toxicity of SNAP. Similar findings of enhanced sensitivity to SNAP were noted with gingival fibroblasts and periodontal ligament cells pretreated with BCNU. The toxicity of SNAP towards the gingival epithelial cells was decreased by cotreatment with the antioxidants, N-acetyl-L-cysteine, L-ascorbic acid, and (+)-catechin. Cells exposed to SNAP exhibited nuclear aberrations, including multilobed nuclei and multinucleation. SNAP-induced cell death was apparently by apoptosis, as noted by fluorescence microscopy and DNA agarose gel electrophoresis.     

In vitro cytotoxicity of (-)-catechin gallate, a minor polyphenol in green tea

The cytotoxicity of (-)-catechin gallate (CG), a minor polyphenolic constituent in green tea, towards cells derived from tissues of the human oral cavity was studied. The sequence of sensitivity to CG was: immortalized epithelioid gingival S-G cells>tongue squamous carcinoma CAL27 cells>salivary gland squamous carcinoma HSG cells>normal gingival HGF-1 fibroblasts. Further studies focused on S-G cells, the cells most sensitive to CG. The response of the S-G cells to CG was dependent on the length of exposure, with midpoint cytotoxicity values of 127, 67 and 58muM CG for 1-, 2- and 3-day exposures, respectively. The sequence of sensitivity of the S-G cells to various green tea catechins was characterized as follows: CG, epicatechin gallate (ECG)>epigallocatechin gallate (EGCG)>epigallocatechin (EGC)>epicatechin (EC), catechin (C). The cytotoxicity of CG, apparently, was not due to oxidative stress as it was a poor generator of H(2)O(2) in tissue culture medium, had no effect on the intracellular glutathione level, its cytotoxicity was unaffected by catalase, and it did not induce lipid peroxidation. However, CG did enhance Fe(2+)-induced, lipid peroxidation. CG-induced apoptosis was detected by nuclear staining, both with acridine orange and by the more specific TUNEL procedure. The lack of caspase-3 activity in cells exposed to CG and the detection of a DNA smear, rather than of discrete internucleosomal DNA fragmentation, upon agarose gel electrophoresis, suggest, possibly, that the mode of cell death was by a caspase-independent apoptotic pathway. The overall cytotoxicity of CG was similar to its epimer, ECG and both exhibited antiproliferative effects equivalent to, or stronger than, EGCG, the most abundant catechin in green tea.     

Effect of resveratrol incorporated in liposomes on proliferation and UV-B protection of cells

The possibility of improving the efficacy of resveratrol, a polyphenol with strong antioxidant and free-radical scavenging properties, on cell proliferation and photoprotection by liposomal incorporation was investigated. Oligolamellar vesicles of different lipid compositions, loaded with resveratrol, were prepared and characterized by evaluating size, zeta potential, incorporation efficiency, electron microscopy and stability over 60 days. The effect of free and liposomal resveratrol on the viability of HEK 293 cells and their photoprotection after UV-B irradiation was assessed by the MTS method. Resveratrol decreased the cell viability at 100microM concentration, while at 10microM increased cell proliferation and also achieved the most effective photoprotection. Photomicrographs of the treated cells from inverted light and fluorescence microscopy demonstrated resveratrol effectiveness at 10microM, as well as its toxicity at higher concentrations, based on changes in cell shape, detachment and apoptotic features. Interestingly, liposomes prevented the cytotoxicity of resveratrol at high concentrations, even at 100microM, avoiding its immediate and massive intracellular distribution, and increased the ability of resveratrol to stimulate the proliferation of the cells and their ability to survive under stress conditions caused by UV-B light.     

In vitro cytotoxicity of protocatechuic acid to cultured human cells from oral tissue: involvement in oxidative stress

Data on the biologic activity of protocatechuic acid are contradictory; some studies have shown that it acts as an antioxidant and suppresses chemical-induced carcinogenesis and others that it induces oxidative stress and promotes tumour formation. The anticarcinogenicity of protocatechuic acid was postulated to be related, in part, to its specific suppression of neoplastic hyperproliferation. To determine whether protocatechuic acid was preferentially antiproliferative to malignant cells, non-malignant and carcinoma cells were exposed for 24 hr to protocatechuic acid (2.5 to 25 mM) and viability was assessed with the neutral red assay. The cell lines were derived from tissues of the human oral cavity, the initial site of exposure upon ingestion of dietary protocatechuic acid, and included normal GN61 gingival fibroblasts, immortalized, non-tumorigenic S-G gingival epithelial cells, and malignant HSG1 cells derived from the salivary gland, HSC-2 cells from the floor of the oral cavity, and CAL27 cells from the tongue. Selective toxicity of protocatechuic acid to malignant cells was not observed. Furthermore, using a total cellular protein determination to quantitate cell growth, no differences in comparative sensitivities of S-G epithelial cells and HSG1 carcinoma cells were noted in a 3 day continuous exposure to 2.5 to 12.5 mM protocatechuic acid and in recovery from a 24 hr exposure to 3 to 15 mM protocatechuic acid. The S-G and HSG1 cells were then used to study the effects of elevated concentrations of protocatechuic acid on oxidative stress. For both cell types, protocatechuic acid induced oxidative stress, presumably through its bioactivation by a tyrosinase pathway. A brief exposure to 25 mM protocatechuic acid lowered the levels of intracellular glutathione and potentiated Fe2+-induced lipid peroxidation of the cells. As determined with the neutral red assay, S-G and HSG1 cells exposed briefly to a non-toxic level (0.5 mM) of the glutathione depleter, 1,3-bis(2-chloroethyl)-N-nitrosourea, were hypersensitive to a subsequent challenge with 10 mM protocatechuic acid and preexposure of the S-G and HSG1 cells to a nontoxic level of protocatechuic acid (2.5 mM) enhanced their sensitivity to a subsequent exposure to tert-butyl hydroperoxide. These findings were consistent with protocatechuic acid, at high levels (> or = 10 mM), acting as an inducer of oxidative stress.     

Antiproliferative and Cytotoxic Effects of Resveratrol in Mitochondria-Mediated Apoptosis in Rat B103 Neuroblastoma Cells

Resveratrol, a natural compound, has been shown to possess anti-cancer, anti-aging, anti-inflammatory, anti-microbial, and neuroprotective activities. In this study, we examined the antiproliferative and cytotoxicity properties of resveratrol in Rat B103 neuroblastoma cells; although it''s molecular mechanisms for the biological effects are not fully defined. Here, we examined the cellular cytotoxicity of resveratrol by cell viability assay, antiproliferation by BrdU assay, DNA fragmentation by DNA ladder assay, activation of caspases and Bcl-2 family proteins were detected by western blot analyses. The results of our investigation suggest that resveratrol increased cellular cytotoxicity of Rat B103 neuroblastoma cells in a dose-and time-dependent manner with IC₅₀ of 17.86 µM at 48 h. On the other hand, incubation of neuroblastoma cells with resveratrol resulted in S-phase cell cycle arrests which dose-dependently and significantly reduced BrdU positive cells through the downregulation of cyclin D1 protein. In addition, resveratrol dose-dependently and significantly downregulated the expression of anti-apoptotic protein includes Bcl-2, Bcl-xL and Mcl-1 and also activates cleavage caspase-9 and-3 via the downregulation of procaspase-9 and -3 in a dose-dependent manner which indicates that involvement of intrinsic mitochondria-mediated apoptotic pathway. In conclusion, resveratrol increases cellular cytotoxicity and inhibits the proliferation of B103 neuroblastoma cells by inducing mitochondria-mediated intrinsic caspase dependent pathway which suggests this natural compound could be used as therapeutic purposes for neuroblastoma malignancies.     

Inhibition of Sphingolipid Metabolism Enhances Resveratrol Chemotherapy in Human Gastric Cancer Cells

Resveratrol, a chemopreventive agent, is rapidly metabolized in the intestine and liver via glucuronidation. Thus, the pharmacokinetics of resveratrol limits its efficacy. To improve efficacy, the activity of resveratrol was investigated in the context of sphingolipid metabolism in human gastric cancer cells. Diverse sphingolipid metabolites, including dihydroceramides (DHCer), were tested for their ability to induce resveratrol cytotoxicity. Exposure to resveratrol (100 μM) for 24 hr induced cell death and cell cycle arrest in gastric cancer cells. Exposure to the combination of resveratrol and dimethylsphingosine (DMS) increased cytotoxicity, demonstrating that sphingolipid metabolites intensify resveratrol activity. Specifically, DHCer accumulated in a resveratrol concentration-dependent manner in SNU-1 and HT-29 cells, but not in SNU-668 cells. LC-MS/MS analysis showed that specific DHCer species containing C24:0, C16:0, C24:1, and C22:0 fatty acids chain were increased by up to 30-fold by resveratrol, indicating that resveratrol may partially inhibit DHCer desaturase. Indeed, resveratrol mildly inhibited DHCer desaturase activity compared to the specific inhibitor GT-11 or to retinamide (4-HPR); however, in SNU-1 cells resveratrol alone exhibited a typical cell cycle arrest pattern, which GT-11 did not alter, indicating that inhibition of DHCer desaturase is not essential to the cytotoxicity induced by the combination of resveratrol and sphingolipid metabolites. Resveratrol-induced p53 expression strongly correlated with the enhancement of cytotoxicity observed upon combination of resveratrol with DMS or 4-HPR. Taken together, these results show that DHCer accumulation is a novel lipid biomarker of resveratrol-induced cytotoxicity in human gastric cancer cells.     

Mediation of the in vitro cytotoxicity of green and black tea polyphenols by cobalt chloride

The effects of Co2+ (as CoCl2) on the cytotoxicity of green tea polyphenol (GTP) and black tea polyphenol (BTP) extracts towards proliferation of immortalized human gingival epithelial-like S-G cells were studied. The 24 h potencies of GTP and BTP extracts, as determined with the neutral red (NR) cell viability assay, were greatly reduced in the presence of 250, but not of 50, microM Co2+. The cytotoxicities of the GTP and BTP extracts were due, in part, to their generation of hydrogen peroxide (H2O2) in the cell culture medium (DMEM). Progressively increasing the concentration of Co2+ in the tea polyphenol-amended cell culture medium resulted in a lowering of the level of H2O2. The cytotoxicity of freshly added H2O2 to S-G cells was abolished in the presence of 250 microM Co2+ and the level of freshly added H2O2 to cell culture medium was progressively lowered as the concentration of Co2+ was increased. Apparently, under the conditions of these studies, the decreases in the cytotoxicity of GTP and BTP extracts in the presence of CoCl2 were due to the rapid catalytic decomposition by Co2+ of the H2O2 generated in the tea polyphenol-amended cell culture medium.     

Cytoprotection by iloprost against paracetamol-induced toxicity in hamster isolated hepatocytes.

1 The ability of iloprost (ZK36374) to protect hamster isolated hepatocytes from the toxic effects of paracetamol and its reactive metabolite N-acetyl-p-benzoquinoneimine (NABQI) was investigated. The cytoprotection provided by iloprost was compared with that of N-acetyl-L-cysteine. 2 Treatment of hepatocytes with either NABQI (0.4 mM) or paracetamol (2 mM) alone resulted in a considerable loss of cell viability, as assessed by trypan blue exclusion or leakage of lactate dehydrogenase, accompanied by an increase in the percentage of viable cells that were blebbed. N-acetyl-L-cysteine (1.25 mM) pretreatment diminished the loss of cell viability and the percentage of blebbed cells resulting from exposure to NABQI or paracetamol, whereas iloprost (10(-16) M to 10(-10) M) pretreatment reduced only the loss of cell viability, not the percentage of viable cells exhibiting blebbing. Pretreatment with N-acetyl-L-cysteine significantly attenuated the depletion by paracetamol of glutathione and decreased the covalent binding of [14C]-paracetamol to cellular proteins, whereas iloprost was without any such effects. 3 The effects of iloprost and N-acetyl-L-cysteine were also investigated by use of a model of paracetamol toxicity in which it is possible to study the biochemical events leading to cell injury separate from the generation of toxic metabolites. Hamster hepatocytes were incubated with paracetamol (4 mM) for 90 min at 37 degrees C during which metabolism of paracetamol occurs with minimal loss of cell viability.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytotoxicity of bioactive polymeric fractions from grape cell culture on human hepatocellular carcinoma, murine leukemia and non-cancerous PK15 kidney cells.

Previously, we isolated two fractions (TP-4 and TP-6) from grape cell culture that were potent catalytic inhibitors in a human DNA topoisomerase II assay for cancer chemoprevention. The objectives of this study were to further assess cytotoxicity of these fractions on cancerous and non-cancerous cells, and to subfractionate and characterize the composition of TP-6, a fraction that was selectively cytotoxic to carcinoma cell lines. Both TP-4 and TP-6 provided significant cytotoxicity to L1210 mouse leukemia cells. Only TP-6, a procyanidin-rich fraction, significantly reduced viability in HepG2 human liver cancer cells, yet unlike resveratrol, caused no cytotoxicity to non-cancerous PK15 pig kidney cells. After further subfractionation of TP-6 (maximal toxicity = 67.2%; ED(50) = 50.5 microM), the cytotoxicity of subfractions on HepG2 cells was TP-6-5 (maximal toxicity=71.8%; ED(50) = 14.1 microM), TP-6-6 (maximal toxicity=64.3%; ED(50) = 67.0 microM), and TP-6-4 (maximal toxicity = 27.6%; ED(50) = 118.0 microM) in descending order. LC-ESI/MS data suggested that cytotoxicity of these procyanidin mixtures to HepG2 cells was proportional to the degree of polymerization. Because TP-6 and its subfractions were selectively cytotoxic to cancerous cell lines tested, they warrant further investigation as potential natural anticancer agents.     

Resveratrol protects human bronchial epithelial cells against nickel‐induced toxicity via suppressing p38 MAPK,NF‐κB signaling,and NLRP3 inflammasome activation

Nickel is a common environmental pollutant that can impair the lung, but the underlying mechanisms have not yet been fully elucidated. Furthermore, natural products are generally used to inhibit cell damage induced by heavy metal. Resveratrol possesses wide biological activities, including anti‐inflammation and antioxidative stress. This study was conducted to explore the toxicity of nickel on human bronchial epithelial (BEAS‐2B) cells and evaluate the protective effect of resveratrol. The results showed that nickel could induce cell apoptosis, increase oxidative stress, and promote the expression of pro‐inflammatory cytokines, including tumor necrosis factor‐α, interleukin (IL)‐1β, IL‐6, IL‐8, C‐reaction protein. Western blot analysis showed that nickel activated p38 mitogen‐activated protein kinase (MAPK), nuclear factor‐kappa B, and nucleotide‐binding oligomerization domain‐like receptor pyrin‐domain‐containing protein 3 pathways, while resveratrol could reverse these effects. Our results suggested that resveratrol could protect BEAS‐2B cells from nickel‐induced cytotoxicity. Therefore, resveratrol is a potential chemopreventive agent against nickel‐induced lung disease.     

Involvement of reactive oxygen species and stress-activated MAPKs in satratoxin H-induced apoptosis

Satratoxins, members of the trichothecene mycotoxin family, have been known to be harmful to health. However, the mechanisms underlying the toxicity still remain unclear. The present study is undertaken to elucidate the mechanisms of the satratoxin H-induced cytotoxicity in PC12 cells. Satratoxin H caused cytotoxicity, which was reflected from apoptosis determined by chromatin staining and flow cytometry. Satratoxin H stimulated the phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). Pre-incubation with SB203580, a p38 MAPK inhibitor, or SP600125, a JNK inhibitor, but not PD98059, an ERK inhibitor, reduced satratoxin-induced cytotoxicity. Co-incubation of cells with glutathione, N-acetyl-L-cysteine or glutathione reductase inhibited cytotoxicity and the phosphorylation of p38 MAPK induced by satratoxin H. Our data suggest that satratoxin H-induced apoptosis in PC12 cells is dependent on the activation of p38 MAPK/JNK and the increase in reactive oxygen species.     

Immunomodulatory activity of resveratrol: discrepant in vitro and in vivo immunological effects

trans-Resveratrol is a dietary polyphenolic compound present in grapes, which has been shown to exhibit strong anti-inflammatory, antioxidant, and chemopreventive activities. In this study we have compared the in vitro and in vivo effects of resveratrol on the development of various cell-mediated immune responses, including mitogen/antigen-induced T cell proliferation, induction of cytotoxic T lymphocytes (CTLs), interleukin-2 (IL-2) induced lymphokine activated killer cells, and cytokine production. We found significant suppression (>90%) of the mitogen/antigen-induced T cell proliferation and development of allo-antigen specific CTLs in vitro with resveratrol at a concentration of 25 microM. Intragastric administration of resveratrol (2 mg daily) to mice for 4 weeks showed no effect on age-related gain in body weight, peripheral blood cell counts (WBC, RBC, or platelets), or the cellularity of bone marrow or spleen. The CD4(+) and CD8(+) T cells in spleen or colony-forming units-total in the marrow also remained unaffected by treatment with resveratrol. Spleen cells, which were stimulated in vitro after being removed from mice which had been administered resveratrol for 2 or 4 weeks, showed no significant change in IL-2 or concanavalin A induced proliferation of T cells or production of IL-2 induced lymphokine activated killer cells. Further, the production of in interferon-gamma and IL-12 was not affected by administration of resveratrol, but production of tumor necrosis factor-alpha was reduced. Even when conducted entirely in vivo, treatment with resveratrol was found to only marginally reduce allo-antigen induced T cell proliferation and the generation of CTLs in the draining lymph nodes. Thus, even though resveratrol strongly inhibits T cell proliferation and production of cytolytic cells in vitro, oral administration of resveratrol for 4 weeks does not induce hematologic or hematopoietic toxicity, and only marginally reduces the T cell-mediated immune responses.     

Dual role of resveratrol in modulation of genotoxicity induced by sodium arsenite via oxidative stress and apoptosis

The potential benefits of resveratrol as an anticancer (proapoptosis) and antioxidant (pro-survival) compound have been studied extensively. However, the role of resveratrol in modulation of the toxicity induced by sodium arsenite (NaAsO₂) is still unclear. In the present study, we examined the effects of resveratrol on NaAsO₂-induced cytotoxicity, DNA and chromosomal damage, cell cycle progression, apoptosis and oxidative stress in human lung adenocarcinoma epithelial (A549) cell line at concentrations from 1 to 20 μM after 24 h exposure. Our results revealed that at 1 and 5 μM, resveratrol was found to exert benefit effects, promoting cell viability and proliferation over 24 h NaAsO₂ exposure, whereas, resveratrol was showed to inhibit cell survival under the same condition at 20 μM. Corresponding to the opposing effect of resveratrol at low vs. high concentrations, DNA and chromosomal damage, cell apoptotic rate and level of oxidative stress were also alleviated by lower concentrations (1, 5 μM) of resveratrol, but exacerbated by higher concentration (20 μM) resveratrol. Our study implicates that resveratrol is the most beneficial to cells at 1 and 5 μM and caution should be taken in applying resveratrol as an anticancer therapeutic agent or nutraceutical supplement due to its concentration dependent effect.     

Resveratrol Enhances Etoposide‐Induced Cytotoxicity through Down‐Regulating ERK1/2 and AKT‐Mediated X‐ray Repair Cross‐Complement Group 1 (XRCC1) Protein Expression in Human Non‐Small‐Cell Lung Cancer Cells

Etoposide (VP‐16), a topoisomerase II inhibitor, is an effective anti‐cancer drug used for the treatment of non‐small‐cell lung cancer (NSCLC). Resveratrol is a naturally occurring polyphenolic compound that has been proved to have anti‐cancer activity. XRCC1 is an important scaffold protein involved in base excision repair that is regulated by ERK1/2 and AKT signals and plays an important role in the development of lung cancer. However, the role of ERK1/2 and AKT‐mediated XRCC1 expression in etoposide treatment alone or combined with resveratrol‐induced cytotoxicity in NSCLC cells has not been identified. In this study, etoposide treatment increased XRCC1 mRNA and protein expression through AKT and ERK1/2 activation in two NSCLC cells, H1703 and H1975. Knockdown of XRCC1 in NSCLC cells by transfection of XRCC1 siRNA or inactivation of ERK1/2 and AKT resulted in enhancing cytotoxicity and cell growth inhibition induced by etoposide. Resveratrol inhibited the expression of XRCC1 and enhanced the etoposide‐induced cell death and anti‐proliferation effect in NSCLC cells. Furthermore, transfection with constitutive active MKK1 or AKT vectors could rescue the XRCC1 protein level and also the cell survival suppressed by co‐treatment with etoposide and resveratrol. These findings suggested that down‐regulation of XRCC1 expression by resveratrol can enhance the chemosensitivity of etoposide in NSCLC cells.