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.     

A novel non-aromatic B-ring flavonoid: Isolation, structure elucidation and its induction of apoptosis in human colon HT-29 tumor cell via the reactive oxygen species-mitochondrial dysfunction and MAPK activation

The aim of the present study was to elucidate the chemical structure of a novel non-aromatic B-ring flavonoid (DHEC) isolated from Macrothelypteris viridifrons and to evaluate its putative molecular mechanism of action on induction of apoptosis in human colon HT-29 cancer cell. On the basis of MS, UV, IR, 1D and 2D NMR data, DHEC was identified as 2-(cis-1, 2-dihydroxy-4-oxo-cyclohex-5-enyl)-5-hydroxy-7-ethoxy-chromone. In addition, the cytotoxicity of DHEC and its effect on induction of apoptosis were confirmed by several assays. After treatment of HT-29 cell with DHEC, we observed the accumulation of intracellular reactive oxygen species, the loss of mitochondrial membrane potential, the alteration of expression of the Bcl-2 family members, the releasing of cytochrome c, the cleavage of poly (ADP-ribose) polymerase (PARP), and the activation of caspase-3, -8, and -9. Further analysis showed that the mitogen-activated protein kinase (MAPK) related proteins were stimulated by treatment with DHEC. These results suggest that DHEC exhibits potential anti-cancer activity in HT-29 cell through induction of apoptosis, which may highly be associated with reactive oxygen species-mitochondrial dysfunction as well as activation of MAPK signaling pathway.     

p-JNK在结肠癌组织中的表达及抑制JNK通路后HT-29细胞增殖和凋亡变化

目的研究p-JNK在结肠癌组织中的表达以及抑制JNK信号通路后人结肠癌HT-29细胞增殖和凋亡的变化。方法使用免疫组织化学方法检测50例结肠癌组织标本和50例正常结肠组织标本中p-JNK的表达情况并和临床资料进行比较分析;在人结肠癌细胞株HT-29中使用SP600125抑制JNK信号通路后,MTT法检测细胞增殖,TUNEL法检测凋亡。结果 p-JNK在结肠癌组织中的表达水平明显高于正常对照组织(P<0.05);并和淋巴结转移、肿瘤分化程度、肿瘤的侵犯深度相关(P<0.05);而与肿瘤部位无关。抑制JNK信号通路后,HT-29细胞中的p-JNK表达降低(P<0.05);增殖减少,凋亡增加(P<0.05)。结论在结肠癌组织中存在p-JNK的高表达,抑制JNK信号通路能降低人结肠癌细胞株HT-29细胞的增殖,并促进凋亡;JNK信号通路和结肠癌的发生发展有关。     

鞘磷脂及神经酰胺对人结肠癌细胞(HT-29)的影响

目的　研究鞘磷脂及其代谢产物神经酰胺对人结肠癌细胞的影响。方法　采用噻唑蓝 (MTT)显色法、细胞核分裂指数和3H TdR掺入试验方法 ,所设剂量分别为鞘磷脂 5、10、2 0、40 μg ml和神经酰胺 6 2 5、12 5、2 5、5 0 μmol L ,分别以无水乙醇和二甲基亚砜 (DMSO)为溶剂对照。结果　鞘磷脂对HT 2 9细胞的生长无明显作用 ,神经酰胺对HT 2 9细胞的生长有明显抑制作用。在MTT试验中 ,不同浓度神经酰胺对HT 2 9细胞的 7d抑制率分别为 3 9%、85 %、98%和98% ;在核分裂指数试验中 ,随着神经酰胺剂量的增高 ,其核分裂指数明显降低 ;在3H TdR掺入试验中 ,可见随着神经酰胺剂量的增高 ,3H TdR掺入到HT 2 9细胞中明显的减少 ,与阴性对照组相比 ,差异有显著性 (P <0 0 5 )。结论　鞘磷脂对HT 2 9细胞生长无明显作用 ,神经酰胺对HT 2 9细胞的生长增殖有明显抑制作用 ,这可能是鞘磷脂抑制结肠癌的机制之一。     

异叶败酱总苷片对人大肠癌HT-29细胞凋亡的影响

目的：研究异叶败酱总苷片对人大肠癌细胞凋亡的影响及作用机制。方法：建立人大肠癌HT-29裸鼠移植瘤模型，设立异叶败酱总苷片低、中、高剂量组和空白组、5-氟脲嘧啶（5-FU）＋甲酰四氢叶酸钙（CF）对照组，给药8周后处死裸鼠，瘤体称重,末端原位标记染色法（TUEL）检测凋亡指数，分别行半胱天冬氨酸蛋白酶-3（caspase-3），Bax和Bcl-2免疫组化染色，图象分析系统定量检测并比较该3种物质表达情况。结果：异叶败酱总苷片各组瘤重小于空白对照组，而凋亡指数均高于空白对照组和5-FU＋CF组，其中高剂量组与空白对照组和5-FU＋CF组比较差异有极显著性（P＜0．01）。异叶败酱总苷片各组移植瘤caspase-3表达及Bax、Bcl-2表达的相对比率（Bax／Bcl-2）均高于空白对照组。结论：异叶败酱总苷片具有诱导人大肠癌HT-29裸鼠移植瘤细胞凋亡的作用，其机制可能与促进移植瘤caspase-3表达及增大Bax／Bcl-2表达比率有关。     

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.     

Evaluation of isoindole derivatives: Antioxidant potential and cytotoxicity in the HT-29 colon cancer cells

Norcantharimides have an isoindole skeleton structure, and some isoindoline derivatives have positive effects on inflammatory pathologies, including cancers. The present study aims to evaluate the antioxidant and cytotoxic potential of four synthesized isoindoline derivatives (NCTD1–4). HT-29 cells exposed to 10, 50, 100, and 200 µM doses of each derivative were incubated for 24 and 48 h, respectively. The cytotoxicity of the new derivatives was analyzed using the cell growth inhibition assay and the cell membrane damage test. In vitro antioxidant activity studies showed that the derivatives have free radical-scavenging effects in a dose-dependent manner. NCTD3 and NCTD4 apparently have antioxidant effects when compared with the control group treated with dimethyl sulfoxide. Furthermore, NCTD4 inhibited the growth of the HT-29 cells due to membrane damage and exhibited a dose-dependent cytotoxic effect on colon adenocarcinoma cells. The findings suggest that NDTD4 has the highest potential for colon cancer treatment and may be interpreted as a candidate anticancer agent.     

Characterization of a profile of the anthocyanins isolated from Vitis coignetiae Pulliat and their anti-invasive activity on HT-29 human colon cancer cells

We isolated anthocyanins from fruits of Vitis coignetiae Pulliat, characterized the anthocyanin profile, and investigated the anti-invasive effects of the anthocyanins on human colon cancer cells. The anthocyanins inhibited cell invasion in a dose-dependent manner, as measured by Matrigel invasion assays, by suppression of matrix metalloproteinase (MMP)-2 and MMP-9 expression. The anti-invasive activity of the anthocyanins was associated with modulation of constitutive nuclear factor κB (NF-κB) activation. The activation of NF-κB triggered by tumor necrosis factor-α was also inhibited by the anthocyanins through suppression IκBα phosphorylation. AIMs inhibited the expression of NF-κB-regulated proteins. In conclusion, this study suggested that the anthocyanins isolated from fruits of V. coignetiae Pulliat should have anti-invasive activities on human colon cancer cells and the activities should be related to the inhibition of NF-κB-regulated proteins such as MMP-2 and MMP-9 expression through the inhibition of NF-κB activation.     

神经酰胺诱导结肠癌HT-29细胞凋亡与线粒体膜电位变化的关系

目的 探索神经酰胺(C2-ceramide,C2-cer)对人结肠癌HT-29细胞增殖、线粒体膜电位改变、细胞凋亡等的影响.方法 正常培养的HT-29细胞分为C2-cer处理组与非处理组,用MTT法、流式细胞仪等方法观察不同时间C2-cer对细胞增殖、线粒体膜电位改变、细胞凋亡等的影响.结果 加入C2-cer可引起HT-29细胞线粒体膜电位 (△Ψm)下降,细胞增殖受抑,并导致细胞凋亡.上述效应与C2-cer剂量以及作用时间相关.结论 C2-cer可导致HT-29细胞线粒体膜电位(△Ψm)下降,抑制细胞增殖,诱导细胞凋亡.     

Induction of apoptosis in HT-29 colon cancer cells by crude saponin from Platycodi Radix

This study examined the apoptotic effects of crude saponins acquired from the roots of Platycodon grandiflorum (SPR) in HT-29 human colon cancer cells.SPR decreased HT-29 cell proliferation in dose- and time-dependent manners by inducing apoptosis via DNA fragmentation and poly (ADP-ribose) polymerase (PARP) cleavage. The apoptosis induced by SPR was associated with the activation of initiator caspases-8 and -9, as well as the effector caspase-3. SPR stimulated Bid cleavage, indicating that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. SPR increased the expression of the pro-apoptotic protein, Bax, and decreased the expression of the anti-apoptotic protein, Bcl-2. SPR also increased the expression of the caspase-independent mitochondrial apoptosis factor, AIF, in HT-29 cells. These results indicate that SPR inhibits HT-29 cell proliferation by inducing apoptosis, which may be mediated via both caspase-dependent and -independent pathways.     

Alpinia pricei rhizome extracts induce apoptosis of human carcinoma KB cells via a mitochondria-dependent apoptotic pathway

Alpinia pricei Hayata (A. pricei) is well known in Taiwan as a traditional Chinese medicine. In this study, the ability of ethanol (70%) extracts of A. pricei rhizome (AP extracts) to induce apoptosis in cultured human carcinoma KB cells was investigated. Treatment of KB cells with various concentrations of AP extracts (25–200 μg/mL) resulted in sequences of events marked by apoptosis, such as loss of cell viability, morphology change, and internucleosomal DNA fragmentation. AP extract-induced apoptotic cell-death was associated with loss of mitochondrial membrane potential, cytochrome c translocation, caspase-3 and -9 activation, and poly ADP-ribose polymerase (PARP) degradation in KB cells. This increase in AP extract-induced apoptosis was also associated with a reduction in the levels of Bcl-2, a potent cell-death inhibitor, and an increase in levels of the Bax protein, which heterodimerizes with and thereby inhibits Bcl-2. Furthermore, AP extracts induced a dose-dependent elevation of reactive oxygen species (ROS) in KB cells. Our findings suggest that A. pricei exerts antiproliferative action and growth inhibition on human carcinoma KB cells through a mitochondria-dependent apoptotic pathway. A. pricei may, therefore, have anticancer properties valuable for application in food and drug products.     

NO-donating aspirin inhibits both the expression and catalytic activity of inducible nitric oxide synthase in HT-29 human colon cancer cells

Nitric oxide-releasing aspirin (NO-ASA) is emerging as a potentially important chemopreventive agent against colon cancer. We examined in HT-29 human colon adenocarcinoma cells the effect of NO-ASA on the inducible form of nitric oxide synthase (NOS2), an enzyme implicated in colon carcinogenesis. NO-ASA inhibited in a time- and concentration-dependent manner the expression of NOS2 up to 70% compared to control (IC50 for this effect = 46 microM). NO-ASA also decreased the corresponding steady-state mRNA levels and this reduction preceded the reduction of protein levels by at least 6 h. NO-ASA also reduced the enzymatic activity of NOS2, as determined by a direct enzyme assay (maximal reduction = 80%) and by determining the accumulation of NO in the culture medium (IC50 for this effect = 36 microM). These effects of NO-ASA on NOS2 were paralleled by inhibition in cell growth (IC50 = 8.5 microM). These findings indicate that NO-ASA profoundly inhibits both the expression and enzymatic activity of NOS2 and suggest that these effects may represent an important mechanism for the colon cancer chemopreventive effect of NO-ASA.     

Tangutorine induces p21 expression and abnormal mitosis in human colon cancer HT-29 cells

A novel beta-carboline alkaloid, tangutorine (benz[f]indolo[2,3-a]quinolizidine) was isolated from the leaves of Nitraria tangutorum L. [Duan JA, Williams ID, Che CT, Zhou RH, Zhao RH, Tangutorine: a novel beta-carboline alkaloid from Nitraria tangutorum. Tetrahedron Lett 1999;40:2593-6], and its unique structural characters led us to initiate a study of its potential anti-proliferation activity. The in vitro treatment with low doses of tangutorine slightly stimulated the proliferation of human colon cancer HT29 cells until at concentrations higher than 6.25 microg/ml when the cell numbers, cellular MTT reduction, and cell proliferation by 3H-thymidine incorporation decreased in a dose-dependent manner (IC50=15 microg/ml=48 microM). Morphological studies of cells by fluorescence and electron microscopy did not show features for apoptosis but only large vacuoles, swollen mitochondria and dense cytoskeletal filaments bunching in the cytoplasm. Immunoblotting analysis revealed a dramatic induction of cyclin kinase inhibitor p21 as well as an inhibition of topoisomerase II expression at 25 microg/ml tangutorine, thereby impeding cell progression from S to G2/M phase. Cells accumulated at G1 phase of the cell cycle at concentrations > or =50 microg/ml tangutorine. Interestingly, some cells escaped from prolonged growth arrest without cell division and resulted in binucleated and polyploid G1 cells. Taken all results together, tangutorine induced a p21 suppression of all cyclins and their associated kinases, such as the topoisomerase II, and thus inhibited normal DNA replication and mitosis.     

Growth-inhibitory effect of Scutellaria lindbergii in human cancer cell lines

Scutellaria lindbergii (Lamiaceae) is Iranian species of Scutellaria. Cytotoxic properties of total methanol extract of S. lindbergii and its fractions were investigated on different cancer cell lines including AGS, HeLa, MCF-7, and PC12. Meanwhile the role of apoptosis was explored in this toxicity. Malignant and non-malignant cells were cultured in DMEM medium and incubated with different concentrations of plant extracts. Cell viability was quantitated by MTT assay. Apoptotic cells were determined using PI staining of DNA fragmentation by flow cytometry (sub-G1 peak). S. lindbergii inhibited the growth of malignant cells in a dose-dependent manner. Among solvent fractions of S. lindbergii, the methylene chloride fraction was found to be more toxic compared to other fractions.     

Celastrol isolated from Tripterygium regelii induces apoptosis through both caspase-dependent and -independent pathways in human breast cancer cells

The aim of the present study was to evaluate the underlying apoptotic mechanisms of celastrol, a major biologically active component of Tripterygium regelii, in human breast adenocarcinoma MCF-7 cells. Celastrol was isolated from T. regelii chloroform extract by silica gel column chromatography, and its chemical structure was identified via ¹H NMR and ¹³C NMR. Celastrol significantly inhibited cell growth in dose- and time-dependent manners. Celastrol induced sub-G1 DNA accumulation, formation of apoptotic bodies, nuclear condensation, and a DNA ladder in MCF-7 cells. Celastrol triggered the activation of caspase family proteins. Celastrol caused activation of caspase-7, -8, and -9, PARP cleavage, caspase-8-mediated bid cleavage, and release of cytochrome c and AIF. In addition, celastrol decreased the expression of anti-apoptotic Bcl-2 protein and increased expression of pro-apoptotic Bax protein. These results suggest that celastrol inhibits the proliferation of MCF-7 cells through induction of apoptosis, which is mediated by a mitochondrial-dependent caspase pathway.     

Study of the cytotoxic activity of beauvericin and fusaproliferin and bioavailability in vitro on Caco-2 cells

Beauvericin (BEA) is a cyclohexadepsipeptide mycotoxin which has insecticidal properties and produces cytotoxic effects in mammalian cells. Fusaproliferin (FUS) is a mycotoxin that has toxic activity against brine shrimp, insect cells, and teratogenic effects on chicken embryos. The aim of this study was to determine the cytotoxicity of BEA and FUS in human epithelial colorectal adenocarcinoma HT-29 and Caco-2 cells, the transepithelial transport and the bioavailability using Caco-2 cells as a simulated in vitro gastrointestinal model of the human intestinal epithelium. The inhibitory concentration (IC₅₀) evidenced by BEA in the Caco-2 cells was 24.6 and 12.7 μM at 24 and 48 h exposure, respectively, whereas the IC₅₀ values evidenced in HT-29 cells were 15.0 and 9.7 μM, respectively. FUS was cytotoxic, but no IC₅₀ data were observed in the range of concentration tested. BEA bioavailability was variable from 50.1% to 54.3%, whereas FUS presented a bioavailability variable from 80.2% to 83.2%. Results obtained demonstrated a potential risk for human health.     

Dynamics of glutathione-S-transferases in Mytilus galloprovincialis exposed to toxic Microcystis aeruginosa cells, extracts and pure toxins

Molluscs and especially bivalves are able to accumulate dinoflagelates, diatoms and cyanobacteria toxins, and, being vectors for these toxins, transfer them along food chains. The data obtained from laboratory experiments showed that bivalve molluscs are resistant to cyanobacteria toxins. In this work, we wanted to test if Mytilus galloprovincialis organs react to microcystins and other cyanobacteria compounds by inducing or decreasing its GST activity. Acclimated mussels M. galloprovincialis were exposed to the toxic Microcystis aeruginosa M13 strain. Exposure of mussels to toxins was done in three ways: living Microcystis cells, crude Microcystis extracts and pure toxins. The measurement of soluble and microsomal GST activity in the different mussel organs was done by using the substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 2,4-dichloro-1-nitrobenzene (DCNB). Analysis of the GST activity of the control mussels using CDNB as a substrate showed that cytosolic activity is much more significant than microsomal. Intact M. aeruginosa cells did not induce any significant response from the mussels, showing that these animals are quite resistant to the cyanobacteria if they are intact. On the other hand, cell extracts caused an important effect in the gut, in the gills and in the labial palps, although in different ways. There was an increase in GST activity in the gut and gills of mussels exposed to Microcystis extracts, showing a response of this detoxication pathway, but in the labial palps a severe reduction in GST activity occurred. Pure MC LR+YR induced an increase in GST activity in all organs but the labial palps. The results showed that other substances apart from microcystins may cause stress to mussels and affect detoxication enzymes such as GST.     

融合受体eDR4/iFas提高sTRAIL对HT-29细胞凋亡的敏感性

目的：探讨sTRAIL联合融合受体eDR4/iFas对HT-29细胞的凋亡作用。方法：采用PCR方法分别扩增eDR4和iFas,通过重叠PCR将两者连接起来组成融合受体基因eDR4/iFas,将其克隆到带Survivin启动子的表达载体上,另外采用组成型启动子CAG调控sTRAIL表达。体外转染结直肠癌细胞株HT-29和人胚肾细胞HEK293,MTT法检测两种细胞的存活率,RTPCR和Western Blot检测目的蛋白的表达,Hoechst染色进一步分析eDR4/iFas联合sTRAIL对HT-29细胞的凋亡效果。结果：在HT-29细胞中,sTRAIL组的细胞存活率为40.9%±18.7%,而eDR4/iFas＋sTRAIL组的细胞存活率为21.6%±9.1%,两者间存在统计学差异（P〈0.05）。结论：eDR4/iFas能提高sTRAIL对HT-29细胞凋亡的敏感性,而对正常细胞HEK293没有毒副作用。     

Apoptosis inducing effects of 6-Methoxydihydrosanguinarine in HT29 colon carcinoma cells

6-methoxydihydrosanguinarine (6ME), a benzophenanthridine alkaloid derived from the methanol extracts of Hylomecon hylomeconoides, showed a dose-dependent effect at 1-10 microM on causing apoptotic cell death in HT29 colon carcinoma cells (IC50 = 5.0+/-0.2 microM). Treatment of HT-29 cells with 6ME resulted in the formation of internucleosomal DNA fragmentation. Treatment of the cells with 6ME caused activation of caspase-3, -8 and 9 protease and subsequent proteolytic cleavage of poly(ADP-ribose)polymerase. 6ME increased the expression of p53 and Bax and decreased the expression of Bid. These results indicate that p53 and proapoptotic Bcl-2 family proteins might participate in the antiproliferative activity of 6ME in HT29 cells.