Bjcul,a snake venom lectin,modulates monocyte-derived macrophages to a pro-inflammatory profile in vitro

Macrophages are cells of high plasticity and can act in different ways to ensure that the appropriate immune response remains controlled. This study shows the effects of the C-type Bothrops jararacussu venom lectin (BJcuL) on the activation of human macrophages derived from the U937 cell line. BJcuL binds on the cell surface, and this event is inhibited by its specific carbohydrate. It induced phagocytosis and production of H₂O₂, and expression of antigen presentation molecules. It also enhanced the production of TNF-α, GM-CSF and IL-6 by macrophages and indirectly induced T cells to an increased production of TNF-α, IFN-γ and IL-6 in the presence of LPS. Our results suggest that BJcuL can modulate macrophage functional activation towards an M1 state.     

FAK反义寡核苷酸对卵巢癌细胞凋亡、黏附和侵袭性的影响

目的观察黏着斑激酶的反义寡核苷酸对卵巢腺癌细胞株OVCAR-3凋亡、黏附和侵袭性的影响。方法实验分4组,反义寡核苷酸组、正义寡核苷酸组、脂质体组、空白对照组。用脂质体介导的方法,将黏着斑激酶的反义寡核苷酸转入OVCAR-3卵巢癌细胞株,应用流式细胞仪AnnexinV/PI双染色法检测细胞的凋亡率,应用基质胶细胞黏附实验和Boyden小室法检测卵巢癌细胞的体外黏附和侵袭能力。结果 ASODN组卵巢癌细胞的凋亡率与对照组比较差异有统计学意义（P〈0.05）;ASODN组癌细胞与基质胶的粘附率与对照组比较差异有统计学意义（P〈0.05）;ASODN组癌细胞穿透Matrigel胶的细胞数目与对照组比较差异具有统计学意义（P〈0.05）。结论抑制黏着斑激酶的表达能增加卵巢癌细胞株OVCAR-3的凋亡,并降低其黏附和侵袭转移能力。     

Effect of BJcuL (a lectin from the venom of the snake Bothrops jararacussu) on adhesion and growth of tumor and endothelial cells.

Lectins are polyvalent carbohydrate-binding proteins of non-immune origin. Recently, we have isolated and characterized a lectin from the venom of the snake Bothrops jararacussu. This lectin (BJcuL) has been shown to bind to lactose moieties and induce agglutination of erythrocytes. In the present work, we observed that cells from human metastatic breast cancer (MDA-MB-435) and human ovarian carcinoma (OVCAR-5) cell lines adhere, although weakly, to BJcuL. However, BJcuL did not inhibit adhesion of these cells to the extracellular matrix proteins fibronectin, laminin and type I collagen. Importantly, viability of these tumor cells and cells from other human tumor cell lines and a bovine brain endothelial cell line was suppressed by BJcuL. These findings suggest that the lectin BJcuL may serve as an interesting tool for combating tumor progression by inhibiting tumor cell and endothelial cell growth.     

紫花牡荆素对人宫颈癌细胞凋亡和侵袭迁移的影响

目的 观察紫花牡荆素(CAT)对人宫颈癌HeLa和SiHa细胞凋亡和侵袭转移的影响。方法 不同浓度CAT作用于HeLa和SiHa细胞不同时间后,采用MTT法观察药物对细胞活力的影响,流式细胞仪检测凋亡率,划痕试验观察细胞迁移率,基质胶法测定细胞粘附百分率,Transwell试验检测侵袭细胞数,Western blotting分析CAT对SiHa细胞抑制转移蛋白nm23-H1和促转移蛋白MTA1表达的影响。结果 CAT显著抑制HeLa和SiHa细胞活力,增加细胞凋亡率;降低细胞迁移百分率和黏附百分率;减少侵袭细胞数;明显增加SiHa细胞nm23-H1蛋白表达,降低MTA1蛋白表达。结论 CAT显著诱导人宫颈癌HeLa和SiHa细胞凋亡,抑制其侵袭迁移,提示其具有潜在的抗宫颈癌作用。     

The natural marine anhydrophytosphingosine, Jaspine B, induces apoptosis in melanoma cells by interfering with ceramide metabolism

Marine environment has frequently afforded a variety of biologically active compounds with strong anticancer and cytotoxic properties. In the present study, the mechanism of action of Jaspine B, an anhydrophytosphingosine derivative isolated from the marine sponge Jaspis sp., was investigated. Jaspine B was able to dose- and time-dependently decrease the viability of murine B16 and human SK-Mel28 melanoma cells. On these cells, Jaspine B treatment triggered cell death by typical apoptosis as illustrated by phosphatidylserine externalization, the release of cytochrome c and caspase processing. These effects were associated with increased intracellular ceramide levels owing to perturbed ceramide metabolism. Indeed, Jaspine B exposure strongly inhibited the activity of sphingomyelin synthase (SMS), an enzyme that converts de novo ceramide into the membrane lipid sphingomyelin. Moreover, whereas Jaspine B-induced cell death was enhanced in SMS1-depleted cells, it was strongly inhibited in cells that stably overexpress human SMS1. Finally, the cytotoxic effects of Jaspine B truncated analogs were also shown to be dependent on SMS activity.Altogether, Jaspine B is able to kill melanoma cells by acting on SMS activity and consequently on ceramide formation, and may represent a new class of cytotoxic compounds with potential applications in anticancer melanoma therapy.     

Decursin from Angelicagigas Nakai induces apoptosis in RC-58T/h/SA#4 primary human prostate cancer cells via a mitochondria-related caspase pathway

Decursin is a major biological active component of Angelicagigas Nakai and is known to induce apoptosis of metastatic prostatic cancer cells. However, the apoptotic mechanism of decursin using primary malignant tumor (RC-58T/h/SA#4)-derived human prostate cells is not known. In the present study, we show that treatment of prostate cancer cells with decursin inhibited cell proliferation in a dose-dependent manner. Decursin also induced apoptosis in RC-58T/h/SA#4 cells, as determined by flow cytometry, Hoechst 33258 staining, and DNA fragmentation. Decursin caused activation of caspases-8, -9, and -3 and promoted the apoptotic action of caspase-8-mediated Bid cleavage. Decursin increased the protein levels of Bax and cytosolic cytochrome c as well as cleavage of PARP while decreasing the protein levels of Bcl-2. Furthermore, the caspase-independent mitochondrial apoptosis factor, apoptosis-inducing factor (AIF), was upregulated by treatment with decursin. Taken together, these findings indicate that decursin inhibited the proliferation of RC-58T/h/SA#4 cells through induction of apoptosis, which is mediated by both caspase-dependent and -independent apoptotic pathways.     

Zerumbone,Sesquiterpene Photochemical from Ginger,Inhibits Angiogenesis

Here, we investigated the role of zerumbone, a natural cyclic sesquiterpene of Zingiber zerumbet Smith, on angiogenesis using human umbilical vein endothelial cells (HUVECs). Zerumbone inhibited HUVECs proliferation, migration and tubule formation, as well as angiogenic activity by rat aorta explants. In particular, zerumbone inhibited phosphorylation of vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1, which are key regulators of endothelial cell function and angiogenesis. In vivo matrigel plug assay in mice demonstrated significant decrease in vascularization and hemoglobin content in the plugs from zerumbone-treated mice, compared with control mice. Overall, these results suggest that zerumbone inhibits various attributes of angiogenesis, which might contribute to its reported antitumor effects.     

Atractylenolide III, a sesquiterpenoid, induces apoptosis in human lung carcinoma A549 cells via mitochondria-mediated death pathway

Pharmacological agents that are safe and can sensitize the lung cancer are urgently required. We investigated whether Atractylenolide III (ATL-III), the major component of Atractylodes rhizome can induce apoptosis of the lung carcinoma cells. ATL-III inhibited cell growth, increased lactate dehydrogenase release and modulated cell cycle on human lung carcinoma A549 cells. ALT-III induced the activation of caspase-3 and caspase-9 and cleavage of poly-(ADP)-ribose polymerase. ATL-III induced the release of cytochrome c, upregulation of bax expression, and translocation of apoptosis-inducing factor. In addition, ATL-III inhibited the proliferation and capillary tube formation of human umbilical vein endothelial cells. These data indicate that ATL-III is a potential candidate for treatment of human lung carcinoma.     

Induction of apoptosis by cordycepin via reactive oxygen species generation in human leukemia cells

Cordycepin (3′-deoxyadenosin), a specific polyadenylation inhibitor, is the main functional component in Cordyceps militaris, one of the top three renowned traditional Chinese medicines. Cordycepin has been shown to possess many pharmacological activities including immunological stimulation, and anti-bacterial, anti-viral, and anti-tumor effects. However, the mechanisms underlying its anti-cancer mechanisms are not yet understood. In this study, the apoptotic effects of cordycepin were investigated in human leukemia cells. Treatment with cordycepin significantly inhibited cell growth in a concentration-dependent manner by inducing apoptosis but not necrosis. This induction was associated with generation of reactive oxygen species (ROS), mitochondrial dysfunction, activation of caspases, and cleavage of poly(ADP-ribose) polymerase protein. However, apoptosis induced by cordycepin was attenuated by caspase inhibitors, indicating an important role for caspases in cordycepin responses. Administration of N-acetyl-l-cysteine, a scavenger of ROS, also significantly inhibited cordycepin-induced apoptosis and activation of caspases. These results support a mechanism whereby cordycepin induces apoptosis of human leukemia cells through a signaling cascade involving a ROS-mediated caspase pathway.     

Mechanisms of thiosulfinates from Allium tuberosum L.-induced apoptosis in HT-29 human colon cancer cells

This study was performed to elucidate the apoptotic pathways by thiosulfinates, major biologically active components of Allium tuberosum L., in HT-29 human colon cancer cells. Thiosulfinates significantly induced cell death in dose- and time-dependent manners in HT-29 cells, which is associated with apoptosis. Thiosulfinates activated the initiator caspase-8, and -9, and the effector caspase-3. In the present study, thiosulfinates were found to stimulate Bid cleavage, indicating that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. Thiosulfinates down-regulated the expression of the anti-apoptotic protein Bcl-2, and up-regulated the expression of the pro-apoptotic protein Bax. We also found that thiosulfinates increased the expression of AIF, a caspase-independent mitochondrial apoptosis factor, and induced DNA fragmentation and chromatin condensation in HT-29 cells. These results indicate that thiosulfinates from A. tuberosum L. inhibited cell proliferation and activated both the caspase-dependent and caspase-independent apoptotic pathways in HT-29 cells.     

Cytotoxicity,cell cycle arrest,and apoptosis in breast cancer cell lines exposed to an extract of the seed kernel of Mangifera pajang (bambangan)

An extract of Mangifera pajang kernel has been previously found to contain a high content of antioxidant phytochemicals. The present research was conducted to investigate the anticancer potential of this kernel extract. The results showed that the kernel crude extract induced cytotoxicity in MCF-7 (hormone-dependent breast cancer) cells and MDA-MB-231 (non-hormone dependent breast cancer) cells with IC50 values of 23 and 30.5 μg/ml, respectively. The kernel extract induced cell cycle arrest in MCF-7 cells at the sub-G1 (apoptosis) phase of the cell cycle in a time-dependent manner. For MDA-MB-231 cells, the kernel extract induced strong G2-M arrest in cell cycle progression at 24 h, resulting in substantial sub-G1 (apoptosis) arrest after 48 and 72 h of incubation. Staining with Annexin V-FITC and propidium iodide revealed that this apoptosis occurred early in both cell types, 36 h for MCF-7 cells and 24 h for MDA-MB-231cells, with 14.0% and 16.5% of the cells respectively undergoing apoptosis at these times. This apoptosis appeared to be dependent on caspase-2 and -3 in MCF-7 cells, and on caspase-2, -3 and -9 in MDA-MB-231 cells. These findings suggest that M. pajang kernel extract has potential as a potent cytotoxic agent against breast cancer cell lines.     

Anti-proliferative effects of Lethariella zahlbruckneri extracts in human HT-29 human colon cancer cells

This study was performed to elucidate the anti-proliferative effects and the apoptotic mechanisms of extracts from Lethariella zahlbruckneri in HT-29 human colon cancer cells. Both the acetone extract (AEL) and methanolic extract (MEL) of L. zahlbruckneri decreased viable cell numbers in a dose- and time-dependent manner in HT-29 cells. The AEL showed stronger cytotoxicity than MEL. Cell death induced by AEL increased cell populations in the sub-G1 phase, as well as the formation of apoptotic bodies and nuclear condensation, whereas MEL did not. Therefore, the potential of AEL to induce apoptosis was examined. Apoptosis induced by AEL was associated with the activation of initiator caspases-8 and -9, as well as the effector caspase-3. AEL stimulated Bid cleavage. This indicated that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. AEL increased the expression of the pro-apoptotic protein, Bax, and decreased the expression of the anti-apoptotic protein, Bcl-2. AEL also increased the expression of the caspase-independent mitochondrial apoptosis factor, AIF, in HT-29 cells. These results indicate that AEL inhibited HT-29 cell proliferation by inducing apoptosis, which might be mediated via both caspase-dependent and -independent pathways.     

An RNA-directed nucleoside anti-metabolite, 1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd), elicits antitumor effect via TP53-induced Glycolysis and Apoptosis Regulator (TIGAR) downregulation

1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd) is a ribose-modified nucleoside analog of cytidine with potent anticancer activity in several cancers. The main antitumor mechanism of this promising RNA-directed nucleoside anti-metabolite is efficient blockade of RNA synthesis in cancer cells. Here, we examined the therapeutic potential of this RNA-directed anti-metabolite in in vitro models of nasopharyngeal cancer (NPC). In a panel of 6 NPC cell lines, ECyd effectively inhibited cellular proliferation at nM concentrations (IC₅₀:∼13-44 nM). Moreover, cisplatin-resistant NPC cells were highly sensitive to ECyd (at nM concentration). The ECyd-mediated growth inhibition was associated with G₂/M cell cycle arrest, PARP cleavage (a hallmark of apoptosis) and Bcl-2 downregulation, indicating induction of apoptosis by ECyd in NPC cells. Unexpectedly, ECyd-induced significant downregulation of TIGAR, a newly described dual regulator of apoptosis and glycolysis. More importantly, this novel action of ECyd on TIGAR was accompanied by marked depletion of NADPH, the major reducing power critically required for cell proliferation and survival. We hypothesized that ECyd-induced TIGAR downregulation was crucially involved in the antitumor activity of ECyd. Indeed, overexpression of TIGAR was able to rescue NPC cells from ECyd-induced growth inhibition, demonstrating a novel mechanistic action of ECyd on TIGAR. We demonstrated for the first time that an RNA-directed nucleoside analog, ECyd, exerts its antitumor activity via downregulation of a novel regulator of apoptosis, TIGAR. Moreover, ECyd may represent a novel therapy for NPC.     

Effect of HUVEC apoptosis inducing proteinase from Vipera lebetina venom (VLAIP) on viability of cancer cells and on platelet aggregation

Three cancer cell lines, the human androgen independent prostate cancer PC-3, androgen dependent LNCaP prostate cancer and human chronic myeloid leukaemia cell line K-562, were treated with Sephadex G-100 sf fractions of Vipera lebetina venom and with HUVEC apoptosis inducing heterodimeric metalloproteinase (VLAIP) from the same venom. The venom was separated into nine fractions using size-exclusion chromatography on Sephadex G-100 sf. The effect of V. lebetina venom gel filtration fractions on the viability of studied cancer cells was different: high molecular mass fractions were the most effective on PC-3 cells. The viability of LNCaP cells was inhibited most strongly by the third fraction. The first and the second fractions contain different metalloproteinases including VLAIP that also most effectively reduced the viability of PC-3 cells. VLAIP decreased PC-3 cell viability in a concentration- and time-dependent manner but did not induce apoptosis as shown by DNA fragmentation assay. VLAIP induced changes in cell shape, rounding up and detachment. VLAIP inhibited the PC-3 cell adhesion to extracellular matrix proteins collagen I, fibronectin and vitronectin but not to fibrinogen. VLAIP had no significant effect on the viability of LNCaP and K-562 cells.VLAIP was also capable to inhibit ADP- and collagen-induced platelet aggregation dose-dependently. IC₅₀ was determined to be 1.89 μM and 0.94 μM, respectively.     

Recombinant rubistatin (r-Rub), an MVD disintegrin, inhibits cell migration and proliferation, and is a strong apoptotic inducer of the human melanoma cell line SK-Mel-28

Disintegrins are low molecular weight peptides isolated from viper venom. These peptides bind to integrin receptors using a conserved binding motif sequence containing an RGD or similar motif. As a consequence, disintegrins can inhibit platelet aggregation and inhibit cell migration, proliferation, and initiate apoptosis in cancer cell lines. Rubistatin is a MVD disintegrin cloned from a Crotalus ruber ruber venom gland. The biological activity of MVD disintegrins is poorly understood. Recombinant rubistatin (r-Rub) was cloned into a pET32b plasmid and expressed in reductase-deficient Escherichia coli. Expression was induced with IPTG and the resulting fusion peptide was affinity purified, followed by thrombin cleavage, and removal of vector coded sequences. r-Rub peptide inhibited ADP-induced platelet aggregation by 54% ± 6.38 in whole blood. We assessed the ability of r-Rub to initiate apoptosis in three human cancer cell lines. Cultures of SK-Mel-28, HeLA, and T24 cells were grown for 24 h with 2.5 μM r-Rub followed by Hoechst staining. Chromatin fragmentation was observed in treated SK-Mel-28, but not in T24 or HeLA cells. A TUNEL assay revealed that 51.55% ± 5.28 of SK-Mel-28 cells were apoptotic after 18 h of treatment with 3.5 μM of r-Rub. Cell migration and proliferation assays were performed in order to further characterize the biological effects of r-Rub on SK-Mel-28 cells. At 3 μM, r-Rub inhibited cell migration by 44.4% ± 0.5, while at 3.5 μM it was able to inhibit cell proliferation by 83% ± 6.0.     

Leucurogin, a new recombinant disintegrin cloned from Bothrops leucurus (white-tailed-jararaca) with potent activity upon platelet aggregation and tumor growth

Disintegrins and disintegrins-like proteins are able to inhibit platelet aggregation and integrin-mediated cell adhesion. The aim of this study was to produce one disintegrin-like cloned from Bothrops leucurus venom gland and to characterize it regarding biological activity. The recombinant protein was purified by one step procedure involving anion-exchange chromatography (DEAE-cellulose) and presented a molecular mass of 10.4 kDa. The purified protein was able to inhibit platelet aggregation induced by collagen (IC₅₀ = 0.65 μM) and to inhibit growth of Ehrlich tumor implanted in mice by more than 50% after 7 days administration of 10 μg/day. No effects were observed upon adenosine 5′-diphosphate (ADP)-and arachidonic acid (AA)-induced platelet aggregation. The recombinant protein was recognized by an antibody specific for jararhagin one metalloproteinase isolated from Bothrops jararaca venom, and therefore it was named leucurogin. Anti-angiogenesis effect of leucurogin was evaluated by the sponge implant model. After 7 days administration leucurogin inhibited, in a dose dependent way, the vascularization process in the sponge. Leucurogin represents a new biotechnological tool to understand biological processes where disintegrins-like are involved and may help to characterize integrins that can be involved in development and progression of malignant cells.     

N-Propionyl polysialic acid precursor enhances the susceptibility of multiple myeloma to antitumor effect of anti-NprPSA monoclonal antibody

Aim:

To study the antitumor effect of anti-NprPSA monoclonal antibody (mAb) in combination with ManNPr, a precursor of N-propionyl PSA, in multiple myeloma (MM), and to explore the mechanisms of the action.

Methods:

Human multiple myeloma cell line RPMI-8226 was tested. The cells were pre-treated with ManNPr (1, 2, and 4 mg/mL), and then incubated with anti-NprPSA mAb (1 mg/mL). Cell apoptosis in vitro was detected using MTT assay and flow cytometry. BALB/c nude mice were inoculated sc with RPC5.4 cells. On 5 d after the injection, the mice were administered sc with anti-NprPSA mAb (200 μg/d) and ManNPr (5 mg/d) for 8 d. The tumor size and body weight were monitored twice per week. TUNEL assay was used for detecting apoptosis in vivo. The apoptotic pathway involved was examined using Western blot analysis and caspase inhibitor.

Results:

Treatment of RPMI-8226 cells with anti-NprPSA mAb alone failed to inhibit cell growth in vitro. In RPMI-8226 cells pretreated with ManNPr, however, the mAb significantly inhibited the cell proliferation, decreased the viability, and induced apoptosis, which was associated with cleavage of caspase-3, caspase-8, caspase-9, and poly(ADP-ribose) polymerase. In the mouse xenograft model, treatment with the mAb in combination with ManNPr significantly inhibited the tumor growth, and induced significant apoptosis as compared to treatment with the mAb alone. Moreover, apoptosis induced by the mAb in vivo resulted from the activation of the caspases and poly(ADP-ribose) polymerase.

Conclusion:

The anti-NprPSA mAb in combination with ManNPr is an effective treatment for in vitro and in vivo induction of apoptosis in multiple myeloma.     

Chromene induces apoptosis via caspase-3 activation in human leukemia HL-60 cells

In this study, the potent anti-tumor effects of brown algae on human leukemia HL-60 cells were investigated. The Sargassum siliquastrum extract among the 14 species of brown algae exhibited profound growth inhibitory effect on HL-60 cells in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, therefore, S. siliquastrum was selected for use in further experiments. The highest inhibitory activity of S. siliquastrum on HL-60 cells was detected in the chloroform fraction, and the active compound was identified as a kind of chromene, sargachromanol E (SE). SE treatment showed significant growth inhibitory effects on HL-60 cells in a dose-dependent manner by inducing apoptosis, as evidenced by the formation of apoptotic bodies, fragmented DNA ladder, and the accumulation of DNA in the sub-G₁ phase of cell cycle. SE induced apoptosis was accompanied by downregulation of Bcl-xL, upregulation of Bax, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, z-DEVD-fmk, a caspase-3 inhibitor, significantly inhibited cell cytotoxicity, apoptotic characteristics such as apoptotic bodies, sub-G₁ DNA content, and cleavage of PARP induced by SE. These results suggest that SE exerts its growth inhibitory effects on HL-60 cells through caspase-3-mediated induction of apoptosis. Therefore, SE offers promising chemotherapeuric potential to prevent cancers such as human leukemia.     

Mitochondrial state 3 to 4 respiration transition during Fas-mediated apoptosis controls cellular redox balance and rate of cell death

The role of reactive oxygen species (ROS) production in death receptor-mediated apoptosis is ill defined. We show that ROS levels play a novel role in moderating the rate of cell death in Fas-dependent apoptosis. Treatment of Jurkat T cells with oligomycin (ATP-synthase inhibitor) or FCCP (mitochondrial uncoupler) and Fas activating antibody (CH11), facilitated rapid cell death. ATP levels, DEVDase activity and cytochrome c release were not account for the synergistic killing effect. However, a decrease in cellular ROS production was associated with CH11 treatment and combinations of CH11 with oligomycin or FCCP further inhibited cellular ROS levels. Thus, decreased ROS production is correlated with accelerated cell death. A transition from state 3 to state 4 mitochondrial respiration following apoptotic stimuli accounted for an attenuated membrane potential and as a results mitochondria-derived ROS production capacity diminished. Similar observations were demonstrated in isolated rat liver mitochondria. Transfection with mitochondrial targeted catalase inhibited mitochondrial ROS production and potentiated cell death. These data show that ROS production is important in receptor-mediated apoptosis and may play a pivotal role in cell survival.     

Investigation of the component of Lycopodium serratum extract that inhibits proliferation and mediates apoptosis of human HL-60 leukemia cells

In this study, we investigate a plant commonly used in herbal medicines, Lycopodium serratum, which is believed to have anti-cancer properties. An alcoholic extract of L. serratum (LSE) was investigated for its ability to induce apoptosis in cultured human promyelocytic leukemia HL-60 cells. Treatment of HL-60 cells with various concentrations of LSE (6–100 μg/mL) resulted in a sequence of events characteristic of apoptosis, including loss of cell viability, morphological changes, and increased sub-G₁ DNA content. Serratenediol (SE), a known biologically active agent, was isolated from MC fraction of LSE and was able to demonstrate significant and dose-dependent growth inhibitory effects on HL-60 cells. Similar to the effects observed with the crude LSE, the SE-related effects included the formation of apoptotic bodies and fragmented DNA, as well as the accumulation of DNA in the sub-G₁ phase of the cell cycle. Analysis of the mechanism of these events indicated that SE treated cells had an increased ratio of Bax/Bcl-xL, released the cytochrome c, activated caspase-9, -3, and cleaved poly-ADP-ribose polymerase (PARP); these observations are hallmarks of apoptotic events. Thus, the results suggest that SE can induce apoptosis via regulating the ratio of Bax/Bcl-xL in HL-60 cell lines.