Histone hyperacetylation is involved in the quercetin-induced human leukemia cell death

Quercetin (QU) is recognized as a promising anticancer drug, but its mechanism remains elusive. Here we found that QU induced human leukemia cell death in a dose-dependent manner. However, it did not show a dose-dependent inhibition on ROS generation (indicated by the level of malondialdehyde, MDA) in the same cells. QU showed similar antioxidant activity at concentrations of 50, 75 and 100 microM. Consistent with that, the antioxidant, N-acetyl-cysteine (NAC) could only further decrease the ROS generation and enhance the cell death triggered by QU at the concentrations less than 50 microM. These results indicate that an additional mechanism is involved in the anticancer activity of high concentrations of QU. When the effect of QU on histone acetylation was studied, QU induced significant histone hyperacetylation at 75 and 100 microM, indicating the possible involvement of histone hyperacetylation in the anticancer activity of high concentrations of QU. This conclusion was supported by the findings that when histone acetylation in the cells treated by QU was increased by different concentrations of TSA, the cell death was significantly enhanced. Our results thus provide the first evidence that QU can induce histone hyperacetylation and this induction of histone hyperacetylation may represent an unrevealed mechanism in its anticancer activity.     

Rimonabant-induced apoptosis in leukemia cell lines: Activation of caspase-dependent and -independent pathways

Rimonabant (SR141716), a cannabinoid CB1 receptor antagonist known for anti-obesity activity, has more recently been shown to inhibit tumor cell growth. Here we demonstrated the antitumor potential of SR141716 in leukemia-derived cell lines and its low toxicity in normal cells (PBMC). SR141716 (1-20 μM range of doses) reduced Jurkat and U937 cell number by activating death signals as well as affecting cell cycle progression. The most prominent response in U937 to SR141716 was a G₀/G₁ block, while in Jurkat cells there was activation of cell death processes. SR141716-treated cells exhibited the morphological and biochemical features of apoptosis and to some extent necrosis. Apoptotic mode of cell death was confirmed in both cell lines by analysis of cell morphology, phosphatidylserine exposure and DNA fragmentation. Moreover, the drug was found to induce an early and robust mitochondrial membrane depolarization. In Jurkat cells the apoptotic process was typically caspase-dependent, while in U937 caspase-independent pathways were also activated. The contribution of PARP activation to SR141716-induced apoptosis in U937 was suggested by protein PARylation, AIF release and apoptosis reversal by PARP inhibitors. Moreover, SR141716 negatively modulated, especially in U937, the PI3K/AKT pathways. In conclusion, our data indicate that SR141716 elicits alternative response and/or cell death pathways depending on the cell type affected.     

Antiproliferative activity of Solanum lycocarpum alkaloidic extract and their constituents, solamargine and solasonine, in tumor cell lines

Natural products are some of the important sources of new anticancer drugs. The Brazilian flora is considered one of the most diverse in the word, although not many large-scale pharmacological and phytochemical studies have been conducted to date. With this in mind, in the present study we evaluated the antiproliferative activity of Solanum lycocarpum fruit glycoalkaloid extract (SL) and its major compounds, solamargine (SM) and solasonine (SS), against different tumor cell lines: murine melanoma (B16F10), human colon carcinoma (HT29), human breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), human hepatocellular liver carcinoma (HepG2) and human glioblastoma (MO59J, U343 and U251). The antiproliferative activity was evaluated using XTT assay and results were expressed as IC₅₀. The most pronounced antiproliferative activity was observed for SM, with IC₅₀ values ranging from 4.58 to 18.23 μg/mL. The lowest IC₅₀ values were observed against HepG2, being 9.60 μg/mL for SL, 4.58 μg/mL for SM and 6.01 μg/mL for SS. Thus, SL, SM and SS demonstrated antiproliferative activity against the tumor cell lines tested, and were most effective against the HepG2 cell line.     

Uncovering the vasorelaxant effect induced by Vale do São Francisco red wine: a role for nitric oxide

The aim of this study was to investigate the mechanisms underlying the vasorelaxant effect induced by the polyphenolic compounds found in red wine from Vale do S?o Francisco. In phenylephrine (10 μM) precontracted mesenteric artery rings, the red wine caused a concentration-dependent relaxation (maximum response to phenylephrine 10 μM = 87.5% ± 6.5%, n = 10). After endothelium removal, the vasorelaxant effect elicited by red wine was attenuated (28.4% ± 4.9%, n = 10). In addition, the vasorelaxant effect induced by red wine in rings pretreated with 100 μM of N(w)-nitro-l-arginine methyl ester and 10 μM of 1H-[1,2,4] oxadiazolo-[4,3-a]-quinoxalin-1-one was attenuated (23.4% ± 5.1%, n = 7 and 11.8% ± 2.7%, n = 6, respectively). Pretreatment with atropine did not affect the vasorelaxant effect induced by red wine (81% ± 3.9%, n = 6). Furthermore, in rabbit aortic endothelial cell line, red wine 100 and 300 μg/mL caused concentration-dependent increases in nitric oxide levels (58 ± 1; 82 ± 7.9; Δ% of fluorescence, n = 5, respectively). In conclusion, we suggest that the alcohol free-lyophilized red wine induces an endothelium-dependent vasorelaxant effect due, at least in part, to a secondary increase in the concentration of nitric oxide and that this effect might be associated with phenolic compounds found in the red wine.     

Vitamin K3 triggers human leukemia cell death through hydrogen peroxide generation and histone hyperacetylation

Vitamin K3 (VK3) is a well-known anticancer agent, but its mechanism remains elusive. In the present study, VK3 was found to simultaneously induce cell death, reactive oxygen species (ROS) generation, including superoxide anion (O2*-) and hydrogen peroxide (H2O2) generation, and histone hyperacetylation in human leukemia HL-60 cells in a concentration- and time-dependent manner. Catalase (CAT), an antioxidant enzyme that specifically scavenges H2O2, could significantly diminish both histone acetylation increase and cell death caused by VK3, whereas superoxide dismutase (SOD), an enzyme that specifically eliminates O2*-, showed no effect on both of these, leading to the conclusion that H2O2 generation, but not O2*- generation, contributes to VK3-induced histone hyperacetylation and cell death. This conclusion was confirmed by the finding that enhancement of VK3-induced H2O2 generation by vitamin C (VC) could significantly promote both the histone hyperacetylation and cell death. Further studies suggested that histone hyperacetylation played an important role in VK3-induced cell death, since sodium butyrate, a histone deacetylase (HDAC) inhibitor, showed no effect on ROS generation, but obviously potentiated VK3-induced histone hyperacetylation and cell death. Collectively, these results demonstrate a novel mechanism for the anticancer activity of VK3, i.e., VK3 induced tumor cell death through H2O2 generation, which then further induced histone hyperacetylation.     

Cytotoxic effects of Eryngium kotschyi and Eryngium maritimum on Hep2, HepG2, Vero and U138 MG cell lines

Abstract

Context: Eryngium maritimum L. and the endemic Eryngium kotschyi Boiss. of the Apiaceae family are used for antiinflammatory, antivenom, antinociceptive and diuretic purposes in folk medicine in Turkey.

Objective: This study investigated the cytotoxic effects of the plant extracts belonging to Eryngium L. genus on various cell lines.

Materials and methods: Cytotoxic activites of the lyophilized aqueous aereal and root parts of the plant extracts on human hepatocellular carcinoma (HepG2), human laryngeal epidermoid carcinoma (Hep2), human glioma (U138-MG) and African green monkey kidney epithelial (Vero) cell lines at 8.33–266.62?µg/ml concentrations were analyzed by lactate dehydrogenase (LDH) leakage and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) cell viability assays.

Results: Inhibitory concentration 50 (IC₅₀) values were found <100?µg/ml in most cases varying around 16.33–125.66?µg/ml. IC₅₀ values for E. kostchyi and E. maritimum root parts on Hep2 cells (32.86 and 30.25?µg/ml, respectively), E. kotschyi aereal, E. maritimum aereal and root parts on HepG2 cells (31.75, 32.42 and 35.01?µg/ml, respectively) by MTT assay were found to be close to the US National Cancer Institute (NCI) recommendations (IC₅₀?<?30?µg/ml) to define the antivity aganist cancer cells. The lowest IC₅₀ values according to the LDH method were observed in Hep2 cells and the highest in U138-MG cells. Root parts were found to be more toxic than aereal parts for both plants in both methods in general.

Discussion and conclusion: Both plant extracts exerted cytotoxic activity aganist Hep2 and HepG2 cells, with low IC₅₀ values defining their promising anticancer property according to NCI; however, further analysis are needed to confirm their activity.     

Chlorpyrifos induces apoptosis in human monocyte cell line U937

In order to investigate chlorpyrifos-induced cell death and its underlying mechanism in human immune cells, a human monocyte like cell line (U937) was treated with chlorpyrifos at 4.45-570microM for 0.5-24h at 37 degrees Celsius in a 5% CO(2) incubator. We first found that chlorpyrifos induced cell death of U937 in a dose- and time-dependent manner, as shown by LDH and MTT assays and PI uptake. Then, we investigated if chlorpyrifos-induced cell death consisted of apoptosis, as determined by analysis of Annexin-V staining and the intracellular level of active caspase-3 by flow cytometry, and DNA fragmentation analysis. We found that chlorpyrifos induced apoptosis in U937 in a time- and dose-dependent manner, as shown by Annexin-V staining. DNA fragmentation was detected when cells were treated with 71 to 284microM chlorpyrifos for 4 or 6h. Chlorpyrifos also induced an increase of intracellular active caspase-3 in U937 cells in a dose-dependent manner, and a caspase-3 inhibitor, Z-DEVD-FMK, significantly inhibited the chlorpyrifos-induced apoptosis. These findings indicate that chlorpyrifos can induce apoptosis in U937 cells, and this effect is partially mediated by activation of intracellular caspase-3.     

Extracts of marine sponge <Emphasis Type="Italic">Polymastia janeirensis</Emphasis> induce oxidative cell death through a caspase-9 apoptotic pathway in human U138MG glioma cell line

We have studied the apoptotic pathway activated in response to marine sponge extracts of Polymastia janeirensis. The effect on intracellular ROS production was also examined. Exposure of U138MG glioma cell line to doses higher than 5 μg/mL has decreased glioma cell viability, with an IC₅₀ <15 μg/mL for both aqueous and organic extracts. However, extracts at higher doses (50 and 100 μg/mL) have stronger cytotoxic effects, decreasing more than 90% of glioma cell viability. The antioxidant Trolox? (100 μM) reversed the cell death percentage induced by extracts at 10 and 25 μg/mL. The type of cell death induced by such high doses was predominantly necrosis, while a high percentage of apoptotic glioma cells was found at 10 μg/mL. Moreover, inhibition of caspase-8 with Z-IETD (a caspase-8 inhibitor) had no effect on the amount of apoptosis induced by 10 μg/mL, but inhibition of caspase-9 with Z-LEHD (a caspase-9 inhibitor) decreased apoptosis. We also observed a dose-dependent increase in ROS production, and similarly to effects observed on viability of glioma cells, and on cell death, higher doses also had more severe effects. Co-treatment with Trolox? significantly reduced ROS production by extracts at doses lower than 50 μg/mL. This is a first report demonstrating that marine sponge extracts of P. janeirensis induce oxidative cell death through a caspase-9 apoptotic pathway.     

Selective proapoptotic activity of polyphenols from red wine on teratocarcinoma cell,a model of cancer stem-like cell

Cancer stem cells are expected to be responsible for tumor initiation and metastasis. These cells are therefore potential targets for innovative anticancer therapies. However, the absence of bona fide cancer stem cell lines is a real problem for the development of such approaches. Since teratocarcinoma cells are totipotent stem cells with a high degree of malignancy, we used them as a model of cancer stem cells in order to evaluate the anticancer chemopreventive activity of red wine polyphenols (RWPs) and to determine the underlying cellular and molecular mechanisms. We therefore investigated the effects of RWPs on the embryonal carcinoma (EC) cell line P19 which was grown in the same culture conditions as the most appropriate normal cell line counterpart, the pluripotent embryonic fibroblast cell line NIH/3T3. The present study indicates that RWPs selectively inhibited the proliferation of P19 EC cells and induced G1 cell cycle arrest in a dose-dependent manner. Moreover, RWPs treatment specifically triggered apoptosis of P19 EC cells in association with a dramatic upregulation of the tumor suppressor gene p53 and caspase-3 activation. Our findings suggest that the chemopreventive activity of RWPs on tumor initiation and development is related to a growth inhibition and a p53-dependent induction of apoptosis in teratocarcinoma cells. In addition, this study also shows that the EC cell line is a convenient source for studying the responses of cancer stem cells to new potential anticancer agents.     

Deglycosylated bleomycin induces apoptosis in lymphoma cell via c-jun NH2-terminal kinase but not reactive oxygen species

Bleomycin (BLM) has demonstrated potent activity in treating malignant lymphomas but its therapeutic efficacy is hampered by induction of lung fibrosis. This side effect is related to the ability of the drug to generate reactive oxygen species in lung cells. In the present study, we evaluated the consequences of deglycosylation of BLM in term of cytotoxic activity and generation of reactive oxygen species. When tested on U937 human lymphoma cells, both compounds generated a typical apoptotic phenotype. Cell death induction was associated with Bax oligomerization, dissipation of the mitochondrial membrane potential, release of cytochrome c, caspase activation, chromatin condensation and internucleosomal degradation. Whereas both reactive oxygen species and c-jun NH₂-terminal kinase (JNK) inhibitors prevented BLM-induced U937 cell death, only JNK inhibition prevented deglycosylated BLM-mediated cell death. Both compounds induced clustering of TRAIL receptors (DR4 and DR5) and Fas at the cell surface but neither a chimeric soluble DR5 receptor that inhibits TRAIL-induced cell death nor a dominant negative version of the adaptor molecule Fas-associated death domain prevented BLM-induced cytotoxicity. These observations indicate that deglycosylation of BLM does not impair the ability of the drug to trigger cell death through activation of the intrinsic pathway but prevents induction of reactive oxygen species. This observation suggests that deglycosylated BLM could exhibit less toxic side effects and could warrant its use in clinic.     

A novel quinoline,MT477: suppresses cell signaling through Ras molecular pathway,inhibits PKC activity,and demonstrates in vivo anti-tumor activity against human carcinoma cell lines

MT477 is a novel thiopyrano[2,3-c]quinoline that has been identified using molecular topology screening as a potential anticancer drug with a high activity against protein kinase C (PKC) isoforms. The objective of the present study was to determine the mechanism of action of MT477 and its activity against human cancer cell lines. MT477 interfered with PKC activity as well as phosphorylation of Ras and ERK1/2 in H226 human lung carcinoma cells. It also induced poly-caspase-dependent apoptosis. MT477 had a dose-dependent (0.006 to 0.2 mM) inhibitory effect on cellular proliferation of H226, MCF-7, U87, LNCaP, A431 and A549 cancer cell lines as determined by in vitro proliferation assays. Two murine xenograft models of human A431 and H226 lung carcinoma were used to evaluate tumor response to intraperitoneal administration of MT477 (33 microg/kg, 100 microg/kg, and 1 mg/kg). Tumor growth was inhibited by 24.5% in A431 and 43.67% in H226 xenografts following MT477 treatment, compared to vehicle controls (p < 0.05). In conclusion, our empirical findings are consistent with molecular modeling of MT477's activity against PKC. We also found, however, that its mechanism of action occurs through suppressing Ras signaling, indicating that its effects on apoptosis and tumor growth in vivo may be mediated by Ras as well as PKC. We propose, therefore, that MT477 warrants further development as an anticancer drug.     

Riccardin D induces cell death by activation of apoptosis and autophagy in osteosarcoma cells

Macrocyclic bisbibenzyls, characteristic components derived from liverworts, have various biological activities. Riccardin D (RD), a liverwort-derived naturally occurring macrocyclic bisbibenzyl, has been found to exert anticancer effects in multiple cancer cell types through apoptosis induction. However, the underlying mechanisms of such effects remain undefined. In addition, whether RD induces other forms of cell death such as autophagy is unknown. In this study, we found that the arrest of RD-caused U2OS (p53 wild) and Saos-2 (p53 null) cells in G1 phase was associated with the induction of p53 and p21^WAF1 in U2OS cells. RD-mediated cell cycle arrest was accompanied with apoptosis promotion as indicated by changes in nuclear morphology and expression of apoptosis-related proteins. Further studies revealed that the antiproliferation of RD was unaffected in the presence of p53 inhibitor but was partially reversed by a pan-inhibitor of caspases, suggesting that p53 was not required in RD-mediated apoptosis and that caspase-independent mechanisms were involved in RD-mediated cell death. Except for apoptosis, RD-induced autophagy occurred as evidenced by the accumulation of microtubule-associated protein-1 light chain-3B-II, formation of AVOs, punctate dots, and increased autophagic flux. Pharmacological blockade of autophagy activation markedly attenuated RD-mediated cell death. RD-induced cell death was significantly restored by the combination of autophagy and caspase inhibitors in osteosarcoma cells. Overall, our study revealed RD-induced caspase-dependent apoptosis and autophagy in cancer cells, as well as highlighted the importance of continued investigation on the use of RD as a potential anticancer candidate.     

Design and discovery of novel pyrazole-pyrrolopyrimidine derivatives as anti-glioma agents via promoting apoptosis,inhibiting cell cycle and EGFR-TK

Glioma is an aggressive type of brain malignancy responsible for significant morbidity and mortality. In the current scenario, epidermal growth factor receptor (EGFR) kinases targeted therapy showed significant benefits in glioma patients. Therefore, in the present study, we intend to investigate the anti-glioma potential of a novel class of pyrazole-pyrrolopyrimidine derivatives and their mechanism of action. The compounds will be synthesized in a straight-forward synthetic route in excellent yields and subsequently tested for EGFR kinase inhibition. The compounds showed a diverse range of inhibitory activity against EGFR (IC₅₀ = 3.4–873.2 nM). With an IC₅₀ of 1.5 nM, compound 4i was determined to be the most effective EGFR inhibitor, even superior to the standard erlotinib (IC₅₀ 2.3 nM). Among them, the three most potent compounds ( 4i , 4j , and 4k ) were further subjected to the anticancer activity against the panel of various cancer cell lines MCF-7 (breast cancer), A549 (lung cancer), U87 (glioblastoma cell)-EGFR-Wild Type, U87 (mutant glioblastoma cells) EGFR-mutant cell, MCF-12A (normal cells). The compound 4i showed the most potent activity against glioblastoma cells as compared to other cancer cells. The effect of compound 4i was also studied on the apoptosis of U87 cells, where it showed induction of apoptosis in a concentration-dependent manner. It also showed inhibition of the G2/M cell cycle phase of U87 cells. Our study demonstrated the development of novel pyrazole-pyrrolopyrimidine derivatives as a novel class of anti-glioma agents.     

Evidence that curcumin suppresses the growth of malignant gliomas in vitro and in vivo through induction of autophagy: role of Akt and extracellular signal-regulated kinase signaling pathways

Autophagy is a response of cancer cells to various anticancer therapies. It is designated as programmed cell death type II and characterized by the formation of autophagic vacuoles in the cytoplasm. The Akt/mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase (p70S6K) and the extracellular signal-regulated kinases 1/2 (ERK1/2) pathways are two major pathways that regulate autophagy induced by nutrient starvation. These pathways are also frequently associated with oncogenesis in a variety of cancer cell types, including malignant gliomas. However, few studies have examined both of these signal pathways in the context of anticancer therapy-induced autophagy in cancer cells, and the effect of autophagy on cell death remains unclear. Here, we examined the anticancer efficacy and mechanisms of curcumin, a natural compound with low toxicity in normal cells, in U87-MG and U373-MG malignant glioma cells. Curcumin induced G(2)/M arrest and nonapoptotic autophagic cell death in both cell types. It inhibited the Akt/mTOR/p70S6K pathway and activated the ERK1/2 pathway, resulting in induction of autophagy. It is interesting that activation of the Akt pathway inhibited curcumin-induced autophagy and cytotoxicity, whereas inhibition of the ERK1/2 pathway inhibited curcumin-induced autophagy and induced apoptosis, thus resulting in enhanced cytotoxicity. These results imply that the effect of autophagy on cell death may be pathway-specific. In the subcutaneous xenograft model of U87-MG cells, curcumin inhibited tumor growth significantly (P < 0.05) and induced autophagy. These results suggest that curcumin has high anticancer efficacy in vitro and in vivo by inducing autophagy and warrant further investigation toward possible clinical application in patients with malignant glioma.     

DDTD, an isoflavone derivative, induces cell apoptosis through the reactive oxygen species/apoptosis signal-regulating kinase 1 pathway in human osteosarcoma cells

Osteosarcoma is the most common primary bone tumor associated with childhood and adolescence. In the present study, we investigated the anticancer effect of a new isoflavone derivative, 3',4'-dichloro-3-(3,4-dichlorophenylacetyl)-2,4,6-trihydroxydeoxybenzoin (DDTD) in human osteosarcoma cells. DDTD induced cell apoptosis in human osteosarcoma cell lines (including: U2OS, MG-63, Saos2 and ROS 17/2.8). We found that the accumulation of reactive oxygen species is a critical mediator in DDTD-induced cell death. DDTD induced apoptosis signal-regulating kinase 1 (ASK1) dephosphorylation and its dissociation from 14-3-3. Treatment of osteosarcoma cells with DDTD induced p38 and p53 phosphorylation. Transfection with ASK1, mitogen activated protein kinase (MAPK) kinase (MKK)3/6, and p38 small interfering RNA (siRNA) antagonized the DDTD-induced cell apoptosis. DDTD also triggered the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl2 ratio and Caspase-9 activation. Bax knockdown using a Bax siRNA strategy reduced Bax expression and subsequent cell death. In addition, transfection of cells with ASK1, MKK3/6, and p38 siRNA reduced DDTD-induced p38 activation, p53 phosphorylation and Bax expression. These results suggest that DDTD generates reactive oxygen species and activates the ASK1-MKK3/6-p38-p53-Bax pathway to cause osteosarcoma cell death.     

Role of mitogen-activated protein kinase (MAPK) in troglitazone-induced osteoblastic cell death

Troglitazone, a PPARgamma agonist, has been reported to induce cell death on different cell types. However, its mechanism of action remains unclear. The present study was undertaken to investigate the effect of troglitazone on cell death and to determine its underlying mechanism in MC3T3-E1 cells, an established osteoblast cell line. Troglitazone induced loss of cell viability in a dose- and time-dependent manner, which was accompanied by apoptosis. Troglitazone increased reactive oxygen species (ROS), but troglitazone-induced cell death was not affected by the antioxidant N-acetylcysteine, suggesting that the ROS generation is not involved in the cytotoxicity of troglitazone. Troglitazone-induced cell death was prevented by the PPARgamma antagonist GW9662. Troglitazone treatment inhibited activation of extracellular signal-regulated protein kinase (ERK) and stimulated p38 activation. Troglitazone-induced cell death was increased by the ERK inhibitor U0126 and prevented by transfection with constitutively active MEK1 and the p38 inhibitor SB203580. Troglitazone induced depolarization of mitochondrial membrane potential and its effect was blocked by SB203580 and GW9662. Caspase-3 was activated by troglitazone treatment and pharmacological inhibition of caspase blocked troglitazone-induced cell death. Taken together, these data suggest that troglitazone induces apoptosis via a caspase-dependent mechanism associated with down-regulation of ERK and up-regulation of p38.     

Gallic acid-induced human pulmonary fibroblast cell death is accompanied by increases in ROS level and GSH depletion

Gallic acid (GA), as a polyhydroxylphenolic compound, has various biological properties, including an anticancer effect. However, little is known about the toxicological effect of GA in primary normal cells. In the present study, we investigated the molecular mechanisms of GA on human pulmonary fibroblast (HPF) cell death in relation to apoptosis. HPF cell growth was dose dependently diminished with an IC(50) of approximately 400 μM of GA at 24 hours. GA-induced HPF cell death was accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨ(m)). All the tested caspase inhibitors (e.g., pan-caspase, caspase-3, -8, or -9 inhibitor) did not rescue HPF cells from GA-induced cell death. GA increased reactive oxygen species (ROS) levels and glutathione (GSH)-depleted cell numbers. Caspase inhibitors partially altered ROS levels, but did not reduce GSH-depleted cell number, in GA-treated HPF cells. In conclusion, we demonstrated that GA induced the growth inhibition and death of HPF cells, which was accompanied by ROS increase and GSH depletion.     

Brazilian marine sponge <Emphasis Type="Italic">Polymastia janeirensis</Emphasis> induces apoptotic cell death in human U138MG glioma cell line,but not in a normal cell culture

Summary  Marine sponges have been prominently featured in the area of cancer research. Here, we examined the anti-proliferative effects of crude extracts (aqueous and organic) of the Brazilian marine sponge Polymastia janeirensis in the U138MG human glioma cell line. Moreover, we examined the effects of extracts on selective cytotoxicity in the glioma cells in comparison with a normal cell culture. Exposure of glioma cells to treatments (24 h) resulted in cell number decrease at all doses tested, with both aqueous and organic extracts (IC₅₀ <20 and <30 μg/ml, respectively). Parallel to this result, sponge extracts reduced glioma cell viability (IC₅₀ <15 μg/ml for both extracts). However, higher doses (50 and 100 μg/ml) induced a stronger cytotoxic effect when compared to the lower dose tested (10 μg/ml), inhibiting more than 80% of cellular growth and viability. Propidium iodide uptake and flow cytometry analysis further showed that sponge extracts caused necrosis in the glioma cell line at higher doses, while a high percentage of apoptotic glioma cells were observed at 10 μg/ml. Moreover, apoptosis was prevented by the pan-caspase inhibitor Z-VAD, suggesting that marine sponge extracts, at lower doses, induce caspase-dependent apoptosis in U138MG glioma cells. Surprisingly the extracts herein tested were more effective than temozolomide, a potent inductor of apoptosis used for the treatment of malignant gliomas. Furthermore, our results suggested a selectivity cytotoxic effect on glioma cell line in comparison with a normal cell culture, since the effect on viability found in glioma cells was not observed in astrocyte cultures with the lower dose (10 μg/ml). Thus, this marine sponge may be considered a good candidate for development of new cancer medicines with antitumor activity against gliomas.     

Pyronaridine induces apoptosis in non-small cell lung cancer cells by upregulating death receptor 5 expression and inhibiting epidermal growth factor receptor

Lung cancer is the leading cause of cancer death. Pyronaridine, a synthetic drug of artemisinin, has been used in China for over 30 years for the treatment of malaria, but its effect on non-small cell lung cancer (NSCLC) cells is rarely reported. In this study, we determined the efficacy of pyronaridine in four different NSCLC cell lines and explored its mechanism in H1975. The data showed that pyronaridine could upregulate the expression of TNF-related apoptosis-inducing ligand (TRAIL)-mediated death receptor 5 to promote cellular apoptosis. Meanwhile, the JNK (c-Jun N-terminal kinase) level was detected to be significantly increased after treating with pyronaridine. We used JNK inhibitor and found that it could partially inhibit cell apoptosis. The results showed that epidermal growth factor receptor (EGFR), PI3K, and AKT were downregulated after the treatment of pyronaridine. In summary, pyronaridine can selectively kill NSCLC by regulating TRAIL-mediated apoptosis and downregulating the protein level of EGFR. It is a promising anticancer drug for NSCLC.     

Synergism between arsenite and proteasome inhibitor MG132 over cell death in myeloid leukaemic cells U937 and the induction of low levels of intracellular superoxide anion

Increased oxygen species production has often been cited as a mechanism determining synergism on cell death and growth inhibition effects of arsenic-combined drugs. However the net effect of drug combination may not be easily anticipated solely from available knowledge of drug-induced death mechanisms. We evaluated the combined effect of sodium arsenite with the proteasome inhibitor MG132, and the anti-leukaemic agent CAPE, on growth-inhibition and cell death effect in acute myeloid leukaemic cells U937 and Burkitt's lymphoma-derived Raji cells, by the Chou-Talalay method. In addition we explored the association of cytotoxic effect of drugs with changes in intracellular superoxide anion (O₂⁻) levels. Our results showed that combined arsenite + MG132 produced low levels of O₂⁻ at 6 h and 24 h after exposure and were synergic on cell death induction in U937 cells over the whole dose range, although the combination was antagonistic on growth inhibition effect. Exposure to a constant non-cytotoxic dose of 80 μM hydrogen peroxide together with arsenite + MG132 changed synergism on cell death to antagonism at all effect levels while increasing O₂⁻ levels. Arsenite + hydrogen peroxide also resulted in antagonism with increased O₂⁻ levels in U937 cells. In Raji cells, arsenite + MG132 also produced low levels of O₂⁻ at 6 h and 24 h but resulted in antagonism on cell death and growth inhibition. By contrast, the combination arsenite + CAPE showed high levels of O₂⁻ production at 6 h and 24 h post exposure but resulted in antagonism over cell death and growth inhibition effects in U937 and Raji cells. We conclude that synergism between arsenite and MG132 in U937 cells is negatively associated to O₂⁻ levels at early time points after exposure.