Effect of quaternary benzo[c]phenanthridine alkaloids sanguilutine and chelilutine on normal and cancer cells

Sanguilutine and chelilutine, quaternary benzo[c]phenanthridine alkaloids, were studied for their antiproliferative activities with regard to their ability to induce oxidative stress.We observed potent antiproliferative activities for both alkaloids against three tumour (HeLa; HL-60; A-2780) and two normal (V-79; LEP) cell lines. Both alkaloids were efficient inductors of apoptosis. Statistical analysis revealed higher toxicity for sanguilutine compared to chelilutine and unequal sensitivity with regard to individual cell lines, although independent of the character of the cell line (i.e. tumour vs. normal). Dihydrofluorescein diacetate staining was used to measure intracellular ROS accumulation after treatment with sanguilutine, chelilutine, sanguinarine, and chelerythrine. In addition, anti-oxidative effects were studied. The effects of the alkaloids were compared with the effects of commonly used anti-oxidants, such as trolox, caffeine acid, and chlorogenic acid. None of the tested alkaloids (0.1 and 1 μg/ml) increased ROS production. Pre-incubation of sanguinarine and chelilutine (at all tested concentrations) and sanguilutine and chelerythrine (1 μg/ml) decreased oxidative stress caused by H₂O₂. These findings indicate high antiproliferative and pro-apoptotic effects of sanguilutine and chelilutine that are not accompanied by oxidative stress induction, to the contrary, both alkaloids showed anti-oxidative effects.     

Comparative toxicity and apoptosis induced by diorganotins in rat pheochromocytoma (PC12) cells

As ubiquitous environmental toxicants, organotin (IV) compounds (OTC) accumulate in the food chain and potential effects on human health are disquieting. The present study compared the cytotoxicity of three diorganotins, namely, dimethyltin (DMT), dibutyltin (DBT) and diphenyltin (DPT), in rat pheochromocytoma (PC12) cells, and the molecular mechanisms responsible for their cytotoxic effects were also explored. Twenty-four hours exposure of PC12 cells to DBT and DPT resulted in a concentration-dependent decrease in cell viability with median lethal concentration (LC₅₀) of 2.97 μM and 7.24 μM, respectively. However, DMT at concentrations up to 128 μM had no obvious effect on cell viability. The mechanistic study revealed that the extent of apoptosis was greater for DBT than that for DPT, followed by DMT, as evidenced by acridine orange/ethidium bromide (AO/EB) fluorescent staining method and annexin V-FITC/PI staining flow cytometry analysis, as well as generation of intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP) disruption, release of cytochrome c (Cyt c), and consequent activation of caspase-9, and -3. These investigations suggested that the cytotoxic potency of three diorganotins in PC12 cells was in the order of DBT > DPT ≫ DMT, and these compounds could induce PC12 cells apoptosis through ROS mediated mitochondrial pathway.     

Protection of S-adenosyl methionine against the toxicity of clivorine on hepatocytes

In this study, we investigated the protective effects of S-adenosyl-l-methionine (SAM), which is a precursor of cellular reduced glutathione (GSH), against the hepatotoxicity of pyrrolizidine alkaloid clivorine. MTT assay showed that SAM (5 μM) prevented the cytotoxicity of clivorine on human normal liver L-02 cells. DNA fragmentation assay showed that SAM (5 μM) improved clivorine-induced L-02 cell apoptosis, and the results of Western blot showed that SAM (5 μM) decreased clivorine-induced caspase-3 activation. Cellular GSH analysis showed that when L-02 cells were exposed to different concentrations (0, 3, 10, 30, 50 and 100 μM) of clivorine for 48 h, cellular GSH was decreased in a concentration-dependent manner, while SAM (5 μM) enhanced 50 μM clivorine decreased cellular GSH. Further MTT assay showed that 5 mM GSH and 5 mM N-acetyl-l-cysteine (NAC) both had protective effects against clivorine-induced hepatotoxicity. Our results suggest that SAM has protective effects against the hepatotoxicity of clivorine possibly by enhancing cellular GSH level and increasing cellular defensive ability against clivorine-induced cytotoxicity.     

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.     

Cytotoxicity and genotoxicity of phenazine in two human cell lines

Phenazine was recently identified as a drinking water disinfection byproduct (DBP), but little is known of its toxic effects. We examined in vitro cytotoxicity and genotoxicity of phenazine (1.9–123 μM) in HepG2 and T24 cell lines. Cytotoxicity was determined by an impedance-based real-time cell analysis instrument. The BrdU (5-bromo-2′-deoxyuridine) proliferation and MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) viability assays were used to examine mechanisms of cytotoxicity. Genotoxicity was determined using the alkaline comet assay. Concentration-dependent cytotoxicity was observed in HepG2 cells, primarily due to an antiproliferative effect (BrdU 24 h IC₅₀: 11 μM; 48 h IC₅₀: 7.8 μM) observed as low as 1.9 μM. T24 cells experienced a minor antiproliferative effect (BrdU 24 h IC₅₀: 47 μM; 48 h IC₅₀: 17 μM). IC₅₀ values for HepG2 proliferation and viability were 54–77% lower compared to T24 cells. In both cell lines, IC₅₀ values for proliferation were 66–90% lower than those for viability. At phenazine concentrations producing equivalent cytotoxicity, HepG2 cells (1.9–30.8 μM) experienced no significant genotoxic effects, while T24 cells (7.7–123 μM) experienced significant genotoxicity at ⩾61.5 μM. While these effects were seen at phenazine concentrations above those found in disinfected water, the persistence of the antiproliferative effect and the differential toxicity in each cell line deserves further study.     

Anti-cancer effect and apoptosis induction of cordycepin through DR3 pathway in the human colonic cancer cell HT-29

Cordycepin is known to have many pharmacological effects such as anti-tumorigenic, anti-inflammatory and anti-angiogenic activity. However, cordycepin induced apoptosis through the DR3 pathway in human colon cancer cells has not been studied. The effect of cordycepin on anti-proliferation was investigated in this study. Cordycepin significantly inhibited cell viability in a dose and time-dependent manner. Cordycepin increased sub G1 and G2/M phase arrest on HT-29 cells at the concentration of 100 μM, whereas cordycepin at 200 μM and 400 μM increased G1 phase arrest. Cordycepin induced apoptosis in HT-29 cells in a dose-dependent manner as detected by Hoechst and Annexin V-FITC staining. Intracellular ROS levels were higher in cordycepin treated cells as compared to control cells. The protein related to apoptosis was determined by antibody array. p53 and Bax expression increased treatment with cordycepin for 18 h. DR3, caspase-8, caspase-1, cleaved caspase-3 and cleaved PARP expression increased. These finding suggest that the cordycepin induces apoptosis through the DR3 pathway in human colon cancer HT-29. These findings suggest that cordycepin should be evaluated further as a therapeutic agent in human colon cancer.     

Zinc attenuates ethanol-induced Sertoli cell toxicity and apoptosis through caspase-3 mediated pathways

Ethanol enhances apoptosis in testicular germ cells. Zinc reduces ethanol-induced apoptosis of somatic cells through inhibition of caspase-mediated pathways. Little is known about the effects of ethanol on Sertoli cells and the effects of Zinc on ethanol-induced testicular injury. The hypothesis tested was that ethanol enhances apoptosis of Sertoli cells through up-regulation of caspase-3 and Zinc inhibits ethanol-induced effects. Cultured Sertoli cells (TM4) were exposed to ethanol (160 mM), Zinc (8 μM) and Zinc prior to ethanol for duration of 24 or 48 h and their effects on TM4 cell viability was then investigated by MTT assay. Caspase-3 mRNA expression was also investigated using real-time RT-PCR. Cell viability decreased and caspase-3 mRNA expresstion increased in cells exposed to ethanol, while exposure to Zinc showed opposite effects. Pretreatment with Zinc recovered ethanol-induced anti-proliferative effects and over-expression of caspase-3. Zinc reduced ethanol-induced Sertoli cell toxicity and apoptosis via caspase-3 mediated pathways.     

Ethyl acetate fraction of Garcina epunctata induces apoptosis in human promyelocytic cells (HL-60) through the ROS generation and G0/G1 cell cycle arrest: A bioassay-guided approach

Number of deaths due to cancer diseases is increasing in the world. There is an urgent need to develop alternative therapeutic measures against the disease. Our study reports the cytotoxicity activity of Garcina epunctata (gutifferae) in human promyelocytic leukemia cells (HL-60) and prostate cancer cells (PC-3) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Changes in mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and morphological changes associated with apoptosis were examined by flow cytometry and Hoescht staining respectively. The results of in vitro antiproliferative screening of fractions and extract from G. epunctata indicated that three fractions inhibited the viability of PC-3 cells with IC₅₀ varied from 50 to 88 μ/ml while two fractions inhibited the proliferation of HL-60 cells with IC₅₀ range between 47.5 and 12 μg/ml. Among the entire fraction tested, Hex-EtOAc (75:25) showed cytotoxic effects on the two cell lines and EtOAc fraction was most active only HL-60 cells (12 μg/ml). Treatment of HL-60 cells with G. epunctata (20, 50, 100 μg/ml) for 24 h led to a significant dose-dependent increase in the percentage of cells in sub-G1 phase by analysis of the content of DNA in cells, and a number of apoptotic bodies containing nuclear fragments were observed in cells treated with 100 μg/ml. The EtOAc fraction of G. epunctata treatment significantly arrested HL-60 cells at the G0/G1 phase (p < 0.05) and ROS was significantly elevated as well as the loss of membrane mitochondrial potential in a concentration dependant manner. The results demonstrated that the EtOAc fraction of G. epunctata inhibited the proliferation of HL-60 cells, leading to cell cycle arrest and programmed cell death, which was confirmed to occur through the mitochondrial pathway.     

Tetrandrine regulates hepatic stellate cell activation via TAK1 and NF-κB signaling

We investigated the anti-fibrotic mechanism of tetrandrine, a bisbenzylisoquinoline alkaloid from the Chinese herb, Stephania tetrandra, on the immortalized HSC-T6 rat hepatic stellate cell line. Tetrandrine (0.39–50 μM) dose- and time-dependently inhibited HSC-T6 cell viability within 24 h and exhibited almost no cytotoxicity at concentrations lower than 6.25 μM in the presence of tumor necrosis factor-α (TNF-α). At a much high concentration (50 μM), tetrandrine caused fatal cytotoxity in both HSCs and hepatocytes. TNF-α time-dependently increased α-smooth muscle actin (α-SMA) expression, while a lower concentration of tetrandrine (6.25 μM) prior to TNF-α treatment reduced the expression of α-SMA and TNFR-1-associated death domain (TRADD). TNF-α treatment induced TGF-β-activated kinase-1 (TAK1) and c-Jun N-terminal kinase (JNK) phosphorylation, which were attenuated by tetrandrine. Furthermore, TNF-α treatment activated nuclear factor-κB (NF-κB) nuclear translocation and IκB-α degradation. Tetrandrine treatment prior to TNF-α reduced nuclear phosphorylated and total NF-κB p65, while the cytosolic IκB-α and NF-κB p65 levels significantly increased. In addition, treatment with only tetrandrine induced the cleavage of caspase-3 and PARP within a range of higher concentrations. Tetrandrine-induced apoptosis was confirmed by the TUNEL assay and flow-cytometric analysis. Treatment with only tetrandrine markedly reduced α-SMA expression, except for at lower concentrations of tetrandrine. A higher concentration of tetrandrine (25 μM) induced a significant increase in JNK and extracellular signal-regulated kinase (ERK) phosphorylation, NF-κB nuclear translocation and IκB-α degradation. In conclusion, the anti-fibrogenic effects of tetrandrine on HSCs involved a dosage-dependent signaling pathway, based on the tetrandrine concentration, by regulating TAK1, JNK and NF-κB. The present data provides strong evidence for the anti-fibrotic dosage-dependent signaling pathway of tetrandrine.     

Apoptosis of leukemia K562 and Molt-4 cells induced by emamectin benzoate involving mitochondrial membrane potential loss and intracellular Ca2+ modulation

Leukemia threatens millions of people's health and lives, and the pesticide-induced leukemia has been increasingly concerned because of the etiologic exposure. In this paper, cytotoxic effect of emamectin benzoate (EMB), an excellent natural-product insecticide, was evaluated through monitoring cell viability, cell apoptosis, mitochondrial membrane potential and intracellular Ca²⁺ concentration ([Ca²⁺]_i) in leukemia K562 and Molt-4 cells. Following the exposure to EMB, cell viability was decreased and positive apoptosis of K562 and Molt-4 cells was increased in a concentration- and time- dependent fashion. In the treatment of 10 μM EMB, apoptotic cells accounted for 93.0% to K562 cells and 98.9% to Molt-4 cells based on the control, meanwhile, 63.47% of K562 cells and 81.15% of Molt-4 cells exhibited late apoptotic and necrotic features with damaged cytoplasmic membrane. 48 h exposure to 10 μM EMB increased significantly the great number of cells with mitochondrial membrane potential (MMP) loss, and the elevation of [Ca²⁺]_i level was peaked and persisted within 70 s in K562 cells whilst 50 s in Molt-4 cells. Moreover, a stronger cytotoxicity of EMB was further observed than that of imatinib. The results authenticate the efficacious effect of EMB as a potential anti-leukemia agent and an inconsistency with regard to insecticide-induced leukemia.     

Zinc enhances CDKN2A,pRb1 expression and regulates functional apoptosis via upregulation of p53 and p21 expression in human breast cancer MCF-7 cell

Zinc (Zn) is an essential trace elements, its deficiency is associated with increased incidence of human breast cancer. We aimed to study the effect of Zn on human breast cancer MCF-7 cells cultured in Zn depleted and Zn adequate medium. We found increased cancer cell growth in zinc depleted condition, further Zn supplementation inhibits the viability of breast cancer MCF-7 cell cultured in Zn deficient condition and the IC_25, IC₅₀ value for Zn is 6.2 μM, 15 μM, respectively after 48 h. Zn markedly induced apoptosis through the characteristic apoptotic morphological changes and DNA fragmentation after 48 h. In addition, Zn deficient cells significantly triggered intracellular ROS level and develop oxidative stress induced DNA damage; it was confirmed by elevated expression of CYP1A, GPX, GSK3β and TNF-α gene. Zinc depleted MCF-7 cells expressed significantly (p ≤ 0.001) decreased levels of CDKN2A, pRb1, p53 and increased the level of mdm2 expression. Zn supplementation (IC₅₀ = 15 μM), increased significantly CDKN2A, pRB1 & p53 and markedly reduced mdm2 expression; also protein expression levels of CDKN2A and pRb1 was significantly increased. In addition, intrinsic apoptotic pathway related genes such as Bax, caspase-3, 8, 9 & p21 expression was enhanced and finally induced cell apoptosis. In conclusion, physiological level of zinc is important to prevent DNA damage and MCF-7 cell proliferation via regulation of tumor suppressor gene.     

Activation of caspases and poly (ADP-ribose) polymerase cleavage to induce apoptosis in leukemia HL-60 cells by Inula racemosa

Inula racemosa Hook.f. commonly known as Pushkarmula (Compositae) has been used as a traditional drug in India, China and Europe. In the present study, 95% ethanolic extract of roots and its fractions (n-hexane, chloroform, n-butanol and aqueous) were evaluated for in vitro cytotoxicity against cancer cell lines of colon, ovary, prostate, lung, CNS and leukemia. The n-hexane fraction containing alantolactone and isoalantolactone as its major constituents was further studied for its mode of action in HL-60 cells. The lowest IC₅₀ value of n-hexane fraction was 10.25 μg/ml for Colo-205, a colon cancer cell line whereas, 17.86 μg/ml was the highest IC₅₀ value observed against CNS cancer cell line SF-295. Further studies on HL-60 cells treated with n-hexane fraction at 10, 25 and 50 μg/ml for 6 h, revealed that it induces apoptosis through intrinsic as well as extrinsic pathways by generating reactive oxygen species (ROS) intermediates. Mitochondrial dysfunction prompted the release of cytochrome c, translocation of pro-apoptotic protein (Bax), activation of caspase cascade, resulting in the cleavage of some specific substrates for caspase-3 such as poly (ADP-ribose) polymerase (PARP), which eventually leads to apoptosis. The results of present study strongly support further research and development of bioactive constituents from Inula racemosa as potential anticancer agent with possible therapeutic implication.     

Cytotoxicity and apoptosis induction on RTG-2 cells of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) and decabrominated diphenyl ether (BDE-209)

Recently, the environmental residues of polybrominated diphenyl ethers (PBDEs) have markedly increased. In particular, the levels of certain PBDE congeners in fish have raised concern regarding potential risks associated with dietary PBDEs exposures. However, little is known regarding PBDE-mediated cell injury in relevant in vitro fish cell models. In this study, the cytotoxic effects of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) and decabrominated diphenyl ether (BDE-209) on RTG-2 cells were investigated. RTG-2 cells were incubated with different concentrations of BDE-47 and BDE-209 (1–100 μM) for 72 h, and a set of bioassays were conducted to measure: cell viability (evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and neutral red (NR) uptake), lactate dehydrogenase (LDH) leakage, reactive oxygen species (ROS) formation and cell apoptosis. The results showed that BDE-47 and BDE-209 inhibited the cells viability, increased LDH leakage, and induced cell apoptosis in time and concentration-dependent manner. All significant effects were observed at concentrations of 12.5 μM and above for BDE-47 and 25 μM and above for BDE-209 (P < 0.05). At the concentration of 100 μM BDE-47 and BDE-209, the cell viability of the exposed cells dropped to about 40% and 50% of the control, and the apoptotic rates were 52.6% and 34.6%, respectively. After 12 h exposure, a concentration-dependent increases of BDE-47 and BDE-209 (12.5–100 μM) in ROS formation were observed. Collectively, the results of cell viability, LDH leakage, cell apoptosis and ROS formation demonstrated that the toxic mechanism of PBDEs on RTG-2 might be mediated by oxidative stress.     

Sulforaphane mitigates cadmium-induced toxicity pattern in human peripheral blood lymphocytes and monocytes

Cadmium (Cd) is a highly toxic and widely distributed heavy metal that induces various diseases in humans through environmental exposure. Therefore, alleviation of Cd-induced toxicity in living organisms is necessary. In this study, we investigated the protective role of sulforaphane on Cd-induced toxicity in human peripheral blood lymphocytes and monocytes. Sulforaphane did not show any major reduction in the viability of lymphocytes and monocytes. However, Cd treatment at a concentration of 50 μM induced around 69% cell death. Treatment of IC₁₀-Cd and 100 μM sulforaphane combination for 24 and 48 h increased viability by 2 and 9% in cells subjected to Cd toxicity, respectively. In addition, IC₂₅ of Cd and 100 μM sulforaphane combination recovered 17–20% of cell viability. Cd induced apoptotic and necrotic cell death. Sulforaphane treatment reduced Cd-induced cell death in lymphocytes and monocytes. Our results clearly indicate that when the cells were treated with Cd + sulforaphane combination, sulforaphane decreased the Cd-induced cytotoxic effect in lymphocytes and monocytes. In addition, sulforaphane concentration plays a major role in the alleviation of Cd-induced toxicity.     

Cytotoxicity of flavones and flavonols to a human esophageal squamous cell carcinoma cell line (KYSE-510) by induction of G2/M arrest and apoptosis

In this study, cytotoxic effects of structurally related flavones and flavonols on a human esophageal squamous cell carcinoma cell line (KYSE-510) were determined, and the molecular mechanisms responsible for their cytotoxic effects were studied. The results of MTT assay showed that flavones (luteolin, apigenin, chrysin) and flavonols (quercetin, kaempferol, myricetin) were able to induce cytotoxicity in KYSE-510 cells in a dose- and time-dependent manner, and the cytotoxic potency of these compounds was in the order of: luteolin > quercetin > chrysin > kaempferol > apigenin > myricetin. Flow cytometry and DNA fragmentation analysis indicated that the cytotoxicity induced by flavones and flavonols was mediated by G₂/M cell cycle arrest and apoptosis. Furthermore, the expression of genes related to cell cycle arrest and apoptosis was assessed by oligonucleotide microarray, real-time RT-PCR and Western blot. It was shown that the treatment of KYSE-510 cells with these compounds caused G₂/M arrest through up-regulation of p21^waf1 and down-regulation of cyclin B1 at the mRNA and protein levels, and induced p53-independent mitochondrial-mediated apoptosis through up-regulation of PIG3 and cleavage of caspase-9 and caspase-3. The results of western blot analysis further showed that increases of p63 and p73 protein translation or stability might be contributed to the regulation of p21^waf1, cyclin B1 and PIG3.     

Use of live imaging analysis for evaluation of cytotoxic chemicals that induce apoptotic cell death

We carried out live imaging of PC12 cells expressing SCAT3, a caspase-3 cleavage peptide sequence linking two fluorescent proteins, ECFP and Venus, which function respectively as the donor and acceptor for FRET. Live imaging of SCAT3-expressing cells was performed from 60 to 300 min after exposure to sodium arsenite (NaAsO₂: 0, 1, 5, or 10 μM) was initiated. We then measured the emission ratio of ECFP to Venus to monitor the activity of caspase-3 and found that the ratio was temporally and dose-dependently increased by NaAsO₂. The mean ECFP/Venus emission ratio between 200 and 300 min after exposure to NaAsO₂ at a dose of 5 or 10 μM, but not at 1 μM, was significantly higher than that in the control group. We showed by other methods that NaAsO₂ significantly increased the amount and activity of mature caspase-3 and the amount of nucleosomes generated from DNA fragmentation, and decreased cell viability. However, methods other than live imaging required a longer time and higher doses of NaAsO₂ than did live imaging to detect significant effects. This result suggests that live imaging using SCAT3 is a useful method for the screening of chemical toxicities and for improving the efficiency of toxicity evaluation.     

Sub-lethal concentrations of CdCl2 disrupt cell migration and cytoskeletal proteins in cultured mouse TM4 Sertoli cells

The aims of this study were to examine the effects of CdCl₂ on the viability, migration and cytoskeleton of cultured mouse TM4 Sertoli cells. Time- and concentration-dependent changes were exhibited by the cells but 1 μM CdCl₂ was sub-cytotoxic at all time-points. Exposure to 1 and 12 μM CdCl₂ for 4 h resulted in disruption of the leading edge, as determined by chemical staining. Cell migration was inhibited by both 1 and 12 μM CdCl₂ in a scratch assay monitored by live cell imaging, although exposure to the higher concentration was associated with cell death. Western blotting and immunofluorescence staining indicated that CdCl₂ caused a concentration dependent reduction in actin and tubulin levels. Exposure to Cd^2 + also resulted in significant changes in the levels and/or phosphorylation status of the microtubule and microfilament destabilising proteins cofilin and stathmin, suggesting disruption of cytoskeletal dynamics. Given that 1–12 μM Cd^2 + is attainable in vivo, our findings are consistent with the possibility that Cd^2 + induced impairment of testicular development and reproductive health may involve a combination of reduced Sertoli cell migration and impaired Sertoli cell viability depending on the timing, level and duration of exposure.     

Anti-proliferation,cell cycle arrest and apoptosis induced by a natural xanthone from Gentianopsis paludosa Ma,in human promyelocytic leukemia cell line HL-60 cells

1-hydroxy-3,7,8-trimethoxyxanthone (xanthone 1) was isolated from Gentianopsis paludosa Ma and identified by MS and NMR in our laboratory. In this study, the results showed that xanthone 1 is a potent inducer of anti-proliferation and apoptosis in HL-60 cells. When the cells treated with lower concentrations of xanthone 1 (12.4–74.4 μM), significant proliferation inhibition was detected by cell viability assay and morphological analyses, and conspicuous G1 and G2/M cell cycle arrest were observed by flow cytometric (FCM) analysis. However, when the cells treated with higher doses of xanthone 1 (82.7–330.8 μM), significant apoptosis was observed by double sequential AO/EB staining, DNA fragmentation assay and FCM analysis. In addition, conspicuous DNA damage was detected by comet assay. In short, all the results showed that xanthone 1 had a significant cytotoxic effect and could induce proliferation inhibition and apoptosis in HL-60 cells in a time- and dose-dependent manner. It was possible that xanthone 1 could induce DNA damage in HL-60 cells, which resulted in G1 phase arrest at the lower concentrations and G2/M phase arrest at the higher concentrations, thus inhibiting the cell proliferation, and irreparable DNA damage at the higher concentrations might be responsible for the occurrence of apoptosis.     

Anti-apoptotic effect of memantine against staurosporine- and low-potassium-induced cell death in cerebellar granule cells: a development-dependent effect

Memantine, a NMDA receptor antagonist used in several experimental models of neuronal cell injury, is a neuroprotective agent that can attenuate neuronal apoptosis connected with over-stimulation of NMDA receptors. In the present study, we evaluated the impact of memantine on apoptosis in primary cerebellar granule cell (CGC) cultures at 7 and 12 day in vitro (DIV). Cell death was induced by staurosporine (St, 0.5 μM) or by decreasing the level of potassium in the culture medium (LP, 5 mM KCl). Both treatments induced cell death in CGC with higher cell-damaging effects at 12 DIV and 7 DIV neurons for St and LP, respectively._Memantine (0.1–2 μM) partially attenuated St-induced apoptosis only in 7 DIV CGC as assessed by DNA fragmentation and LDH release, but not caspase-3 activity. During LP-induced apoptosis, memantine decreased LDH release and DNA fragmentation, but not affected caspase-3 activity in 7 and 12 DIV CGC. Interestingly, we found no beneficial effects of other NMDA antagonists, including a competitive antagonist such as AP-5 (100 μM) and an uncompetitive antagonist such as MK-801, (1 μM). In conclusion, our data suggest that the anti-apoptotic effects of memantine in CGC are developmentally regulated and its neuroprotective action occurs through an NMDAR-independent mechanism.     

Colchicine-induced apoptosis in human normal liver L-02 cells by mitochondrial mediated pathways

Colchicine is an alkaloid that has been widely used to treat gout. It also has a curative effect on cancer. Although many studies have shown that its effect on cell apoptosis was mediated by the activation of caspase-3, the pathways involved in the process remained obscure. Here we show some evidence regarding the missing information using human normal liver cells L-02 in our study. The effect of colchicine on apoptosis in L-02 cells and the apoptosis-associated signaling pathways were determined using different tests including cell viability assay, Annexin V and propidium idodide binding, PI staining, Hoechst 33342 staining, mitochondrial membrane potential assay, caspase activity assay and Western blot analysis. We found that colchicine-induced a dose-dependent drop of cell viability in L-02 cells; early apoptosis happened when cells were treated with 0.1 μM of colchicine. The colchicine-induced loss of mitochondrial membrane potential, activation of caspase-3 and 9, up-regulation of Bax and down-regulation of Bcl-2 showed an evidence for the colchicine activity on apoptosis, at least, by acting via the intrinsic apoptotic pathway.