Induction of apoptosis in MCF-7 cells by β-1,3-xylooligosaccharides prepared from Caulerpa lentillifera

β-1,3-Xylan was prepared from the green alga, Caulerpa lentillifera, and hydrolyzed to oligosaccharides by a mild acid treatment. The average degree of polymerization was about 5. The oligosaccharides reduced the number of viable human breast cancer MCF-7 cells in a dose-dependent manner, and induced chromatin condensation and degradation of poly ADP-ribose polymerase, indicating that they induced apoptosis in MCF-7 cells.     

New β-carboline and indole alkaloids from Actinomycete Actinomadura sp. BCC 24717

Four new β-carbolines 1–4 and two new indoles 5–6 were isolated together with thirteen known compounds from actinomycete, Actinomadura BCC 24717. Structures of the new compounds, 1–6, were determined by NMR spectroscopic and MS spectrometric analyses. Compound 4 exhibited cytotoxicity to Vero cells and compound 6 showed antifungal activity with IC₅₀ 35.91 μg/mL and 41.97 μg/mL, respectively.     

Induction of growth cessation by acacetin via β-catenin pathway and apoptosis by apoptosis inducing factor activation in colorectal carcinoma cells

Molecular Biology Reports - Acacetin, a bioflavanoid, contains anti-inflammatory and anti-cancer activities as shown in different experimental models. However, its anticancer potential and...     

Inhibition of indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase by β-carboline and indole derivatives

β-Carboline derivatives inhibited both indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase activities from various sources. Among them, norharman is most potent for both enzymes from mammalian sources. Kinetic studies revealed that norharman is uncompetitive (K_i = 0.12 mm) with l-tryptophan for rabbit intestinal indoleamine 2,3-dioxygenase, and linearly competitive (K_i = 0.29 mm) with l-tryptophan for mouse liver tryptophan 2,3-dioxygenase. In addition, some β-carbolines selectively inhibited one enzyme or the other. Pseudomonad tryptophan 2,3-dioxygenase was inhibited by a different spectrum of β-carbolines. Such a selective inhibition by the structure of substrate analogs is more evident by the use of indole derivatives. Indole-3-acetamide, indole-3-acetonitrile and indole-3-acrylic acid exhibited a potent inhibition for mammalian tryptophan 2,3-dioxygenase, while they moderately inhibited the pseudomonad enzyme. However, they showed no inhibition for indoleamine 2,3-dioxygenase. These results suggest the difference of the structures of the active sites among these enzymes from various sources.     

Mitochondrial dysfunction and biotransformation of β-carboline alkaloids,harmine and harmaline,on isolated rat hepatocytes

The cytotoxic effects and biotransformation of harmine and harmaline, which are known β-carboline alkaloids and potent hallucinogens, were studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to harmine caused not only concentration (0–0.50 mM)- and time (0–3 h)-dependent cell death accompanied by the formation of cell blebs and the loss of cellular ATP, reduced glutathione, and protein thiols but also the accumulation of glutathione disulfide. Of the other analogues examined, the cytotoxic effects of harmaline and harmol (a metabolite of harmine) at a concentration of 0.5 mM were less than those of harmine. The loss of mitochondrial membrane potential and generation of oxygen radical species in hepatocytes treated with harmine were greater than those with harmaline and harmol. In the oxygen consumption of mitochondria isolated from rat liver, the ratios of state-3/state-4 respiration of these β-carbolines were decreased in a concentration-dependent manner. In addition, harmine resulted in the induction of the mitochondrial permeability transition (MPT), and the effects of harmol and harmaline were less than those of harmine. At a weakly toxic level of harmine (0.25 mM), it was metabolized to harmol and its monoglucuronide and monosulfate conjugates, and the amounts of sulfate rather than glucuronide predominantly increased with time. In the presence of 2,5-dichloro-4-nitrophenol (50 μM; an inhibitor of sulfotransferase), harmine-induced cytotoxicity was enhanced, accompanied by decrease in the amount of harmol-sulfate conjugate, due to an increase in the amount of unconjugated harmol and the inhibition of harmine loss. Taken collectively, these results indicate that (a) mitochondria are target organelles for harmine, which elicits cytotoxicity through mitochondrial failure related to the induction of the MPT, mitochondrial depolarization, and inhibition of ATP synthesis; and (b) the toxic effects of harmine are greater than those of either its metabolite harmol or its analogue harmaline, suggesting that the onset of harmine-induced cytotoxicity may depend on the initial and/or residual concentrations of harmine rather than on those of its metabolites.     

Induction of apoptosis in human colon carcinoma COLO 205 cells by the recombinant α subunit of C-phycocyanin

The α-subunit of C-phycocyanin (CpcA) was expressed in Escherichia coli and purified. The recombinant CpcA inhibited the growth of human colon carcinoma COLO 205 cells. Typical apoptotic morphological characteristics, such as chromatin condensation and nuclear fragmentation, were observed in CpcA-treated COLO 205 cells by fluorescence microscopy and transmission electron microscopy. Moreover, the apoptotic process was associated with the Bax/Bcl-2 ratio up-regulation, mitochondrial membrane depolarization, cytochrome c release, and caspase-9 activation. These findings indicate that CpcA induced the death of COLO 205 cells through the intrinsic apoptotic pathway.     

Profilin1 facilitates staurosporine-triggered apoptosis by stabilizing the integrin β1-actin complex in breast cancer cells

Profilin1 (Pfn1) functions as a tumour suppressor against malignant phenotypes of cancer cells. A minimum level of Pfn1 is critical for the differentiation of human epithelial cells, and its lower expression correlates with the tumourigenesis of breast cancer cells and tissues. However, the molecular mechanisms underlying its anti-tumour action remain largely unknown. In this study, we found that stable expression of ectopic Pfn1 sensitized the breast cancer cell line MDA-MB-468 to apoptosis induced by staurosporine, a widely used natural apoptosis-inducing agent. Pfn1 overexpression could also up-regulate the expression of integrin α5β1, which has been shown to inhibit the transformed phenotype of cancer cells. Furthermore, the Pfn1-facilitated apoptosis induced by staurosporine was blocked in cells attached to a supplementary fibronectin substrate, which serves as a ligand of integrin α5β1. These results suggest that the insufficient fibronectin caused by the integrin α5β1 up-regulation might activate a signalling pathway leading to an increase of cellular apoptosis. Moreover, Pfn1 that primarily functions to promote local superstructure formation involving actin filaments and integrin β1 may contribute to its promotion on apoptosis. Our study indicated a previously uncharacterized role of Pfn1 in mediating staurosporine-inducing apoptosis in breast cancer cells via up-regulating integrin α5β1, and suggested a new target for breast cancer therapy.     

Induction of apoptosis in bacillus Calmette-Guérin-activated T cells by transforming growth factor-beta

In view of the critical role played by bacillus Calmette-Guérin (BCG) in the development and functional activation of protective T cells against tuberculosis, it has become important to understand the mechanisms by which cytokines regulate BCG-mediated immune responses. There is evidence that cytokine-mediated suppression of T cell function by mechanisms, including apoptosis, may reduce host resistance in tuberculosis. However, it is unclear whether cytokine-mediated suppression of antigen-responsive T cells through apoptotic mechanisms may be operating during human cellular activation induced by BCG. Here we present evidence, for the first time, that treatment of BCG-activated T cells with transforming growth factor-beta (TGF-beta) induces cellular apoptosis. These results were further supported by the fact that treatment of cells with a blocking mAb directed to TGF-beta significantly inhibited the percentage of apoptosis induced by TGF-beta. Interestingly, TGF-beta-mediated death of BCG-activated T cells in cultures containing interleukin (IL)-12 was observed. Moreover, our results demonstrated the induction of apoptosis by TGF-beta in BCG-activated T cells cultured in the presence of exogenous IL-12. In addition, our data indicated that TGF-beta significantly inhibited both BCG-induced cell growth determined by thymidine uptake and BCG-induced IFN-gamma secretion. Finally, TGF-beta-induced apoptosis in BCG-activated T cells correlated inversely with BCG-induced IFN-gamma secretion. Taken together, these findings indicate that TGF-beta induces apoptosis in human T cells activated with BCG and at the same time suggest that loss of BCG-reactive T cells through apoptotic mechanisms could contribute to an increased susceptibility to Mycobacterium tuberculosis infection.     

Induction of Apoptosis in MCF-7 Cells by β-1,3-Xylooligosaccharides Prepared from Caulerpa lentillifera

β-1,3-Xylan was prepared from the green alga, Caulerpa lentillifera, and hydrolyzed to oligosaccharides by a mild acid treatment. The average degree of polymerization was about 5. The oligosaccharides reduced the number of viable human breast cancer MCF-7 cells in a dose-dependent manner, and induced chromatin condensation and degradation of poly ADP-ribose polymerase, indicating that they induced apoptosis in MCF-7 cells.     

Activation of p53 in gastric cancer cells by tripchlorolide specifically induces apoptosis

There are two possible outcomes when DNA damage occurs in normal mammalian cells: either induction of cell-cycle checkpoint which inhibits the progress of the cell cycles as well as activates DNA repair pathways, or activation of apoptosis to eliminate damaged cells. The p53 tumour-suppressor gene plays a key role in selecting these pathways. In our present works, the human gastric cancer cell line AGS was treated with tripchlorolide, a potent antitumor compound purified from a Chinese herb Tripterygium Wilfordii Hook. Single cell gel electrophoresis (Comet assay) showed that the treatment of tripchlorolide resulted in DNA damage in AGS cells. The damaged AGS cells went through apoptosis, which was time- and dose- dependent.     

Induction of apoptosis in purified animal and plant nuclei by Xenopus egg extracts

We have developed a cell-free system that can trigger the nuclei purified from mouse liver and suspensioncultured carrot cells to undergo apoptosis as defined by the formation of apoptotic bodies and nucleosomal DNA fragments.The effects of different divalent cations and cycloheximide on DNA cleavage in this system were assessed.The fact that nuclei of plant cells can be induced to undergo apoptosis in a cell-free animal system suggests that animals and plants share a common signal transduction pathway triggering in the initiation stage of apoptosis.     

α- and β-receptor control of catecholamine secretion from isolated adrenal medulla cells

Summary The structural characteristics and cellular elements of the boundary zone between the white and red pulp of the human spleen were studied by SEM and TEM. The boundary zone consisted of both the perifollicular region and the region surrounding the periarterial lymphoid sheath. The perifollicular region was further subdivided into two, equally thick layers. The inner half layer of the perifollicular region outside the mantle zone of the lymph follicle was composed of tightly packed medium-sized lymphocytes, interspersed by a small number of reticular cells. The outer half layer was composed of a reticular cell meshwork containing blood cells in vessels, which communicated with the splenic cords of the red pulp. Intermittent rows of reticular cells distinguished the outer from the inner half layer. The region surrounding the periarterial lymphoid sheath revealed the same type of reticular cell meshwork as the outer half layer of the perifollicular region. Capillary ends opened into the reticular cell meshwork, which suggested the presence of an open circulation in the human spleen. A deep lymphatic vessel which communicated with the periarterial lymphoid sheath was noted.     

Differential Involvement of β-Glucosidases from Hypocrea jecorina in Rapid Induction of Cellulase Genes by Cellulose and Cellobiose

Appropriate perception of cellulose outside the cell by transforming it into an intracellular signal ensures the rapid production of cellulases by cellulolytic Hypocrea jecorina. The major extracellular β-glucosidase BglI (CEL3a) has been shown to contribute to the efficient induction of cellulase genes. Multiple β-glucosidases belonging to glycosyl hydrolase (GH) family 3 and 1, however, exist in H. jecorina. Here we demonstrated that CEL1b, like CEL1a, was an intracellular β-glucosidase displaying in vitro transglycosylation activity. We then found evidence that these two major intracellular β-glucosidases were involved in the rapid induction of cellulase genes by insoluble cellulose. Deletion of cel1a and cel1b significantly compromised the efficient gene expression of the major cellulase gene, cbh1. Simultaneous absence of BglI, CEL1a, and CEL1b caused the induction of the cellulase gene by cellulose to further deteriorate. The induction defect, however, was not observed with cellobiose. The absence of the three β-glucosidases, rather, facilitated the induced synthesis of cellulase on cellobiose. Furthermore, addition of cellobiose restored the productive induction on cellulose in the deletion strains. The results indicate that the three β-glucosidases may not participate in transforming cellobiose beyond hydrolysis to provoke cellulase formation in H. jecorina. They may otherwise contribute to the accumulation of cellobiose from cellulose as inducing signals.     

ER stress-mediated apoptosis induced by celastrol in cancer cells and important role of glycogen synthase kinase-3β in the signal network

HeLa cells treated with celastrol, a natural compound with inhibitive effect on proteasome, exhibited increase in apoptotic rate and characteristics of apoptosis. To clarify the signal network activated by celastrol to induce apoptosis, both the direct target proteins and undirect target proteins of celastrol were searched in the present study. Proteasome catalytic subunit β1 was predicted by computational analysis to be a possible direct target of celastrol and confirmed by checking direct effect of celastrol on the activity of recombinant human proteasome subunit β1 in vitro. Undirect target-related proteins of celastrol were searched using proteomic studies including two-dimensional electrophoresis (2-DE) analysis and iTRAQ-based LC-MS analysis. Possible target-related proteins of celastrol such as endoplasmic reticulum protein 29 (ERP29) and mitochondrial import receptor Tom22 (TOM22) were found by 2-DE analysis of total cellular protein expression profiles. Further study showed that celastrol induced ER stress and ER stress inhibitor could ameliorate cell death induced by celastrol. Celastrol induced translocation of Bax into the mitochondria, which might be related to the upregulation of BH-3-only proteins such as BIM and the increase in the expression level of TOM22. To further search possible target-related proteins of celastrol in ER and ER-related fractions, iTRAQ-based LC-MS method was use to analyze protein expression profiles of ER/microsomal vesicles-riched fraction of cells with or without celastrol treatment. Based on possible target-related proteins found in both 2-DE analysis and iTRAQ-based LC-MS analysis, protein–protein interaction (PPI) network was established using bioinformatic analysis. The important role of glycogen synthase kinase-3β (GSK3β) in the signal cascades of celastrol was suggested. Pretreatment of LiCL, an inhibitor of GSK3β, could significantly ameliorate apoptosis induced by celastrol. On the basis of the results of the present study, possible signal network of celastrol activated by celastrol leading to apoptosis was predicted.     

The binding proximity of methyl β-lilacinobioside isolated from Caralluma retrospiciens with topoisomerase II attributes apoptosis in breast cancer cell line

The alterations in somatic genomes that controls the mechanism of cell division as a main cause of cancer, and then the drug that specifically toxic to the cancer cells further complicates the process of the development of the widely effective potential anticancer drug. The side effects of the drug as well as the radiotherapy used for the treatment of cancer is severe; therefore, the search of the natural products from the sources of wild plants having anticancer potential is become immense importance today. The ethno-medicinal survey undertaken in Al-Fayfa and Wadi-E-Damad region of southern Saudi Arabia revealed that the Caralluma retrospiciens (Ehrenb.) N.E.Br. (family Apocynaceae) is being used for the treatment of cancer by the native inhabitants. The biological evaluation of anticancer potential of bioassay-guided fractionations of methanolic extract of whole plant of C. retrospiciens against human breast adenocarcinoma cell line (MCF-7) followed by characterization using spectroscopic methods confirmed the presence of methyl β-lilacinobioside, a novel active constituent reported for the first time from C. retrospiciens, is capable of inhibition of cell proliferation and induction of apoptosis in MCF-7 cells by regulating ROS mediated autophagy, and thus validated the folkloric claim. Based on a small-scale computational target screening, Topoisomerase II was identified as the potential binding target of methyl β-lilacinobioside.     

C ring may be dispensable for β-carboline: Design,synthesis, and bioactivities evaluation of tryptophan analog derivatives based on the biosynthesis of β-carboline alkaloids

According to our previous work and the latest research on the biosynthesis of β-carboline, and using the reverse thinking strategy, tryptophan, the biosynthesis precursor of β-carboline alkaloids, and their derivatives were synthesized, and their biological activities and structure–activity relationships were studied. This bioassay showed that these compounds exhibited good inhibitory activities against tobacco mosaic virus (TMV); especially (S)-2-amino-3-(1H-indol-3-yl)-N-octylpropanamide (4) (63.3 ± 2.1%, 67.1 ± 1.9%, 68.7 ± 1.3%, and 64.5 ± 3.1%, 500 μg/mL) exhibited the best antiviral activity both in vitro and in vivo. Compound 4 was chosen for the field trials and the acute oral toxicity test, the results showed that the compound exhibited good anti-TMV activity in the field and low acute oral toxicity. We also found that these compounds showed antifungal activities and insecticidal activities.     

Induction of oxidative DNA damage in human foreskin fibroblast Hs68 cells by oxidized β-carotene and lycopene

Two recent clinical trials suggest that β-carotene may be harmful to smokers. In this study we examined the hypothesis that β-carotene may become toxic when degradation occurs. β-Carotene (BC) and lycopene (LP) with or without prior heat treatment (60°C for 1h in open air) were incubated at 20 and 40 μM with calf thymus DNA or human fibroblasts Hs68 cells. The heat treatment resulted in ca. 80% and 35% bleaching of BC and LP, respectively. When Hs68 cells were incubated with the oxidized β-carotene (OBC) or oxidized lycopene (OLP) at 37°C for 20h, cell viability was significantly and dose-dependently decreased whereas cell viability was not affected by BC or LP. Cell death, which was already evident at 4h after incubation with OBC or OLP, was possibly attributable to apoptosis, as shown by the increased histone-associated DNA fragmentation. However, cell lysis, measured as release of lactate dehydrogenase, also occurred at 4h after incubation with OBC and OLP, although the extent was relatively small and was greater for OLP than for OBC. When calf thymus DNA was incubated with OBC or OLP at 37°C for 20h, the 8-hydroxy-2-deoxyguanosine (8-OH-dG) level was significantly and dose-dependently increased by OLP whereas the increase by OBC was only significant at 40 μM. When Hs68 cells were incubated with OBC and OLP for 20h, both compounds increased the 8-OH-dG level, but the effect was only significant for 40 μM OLP. Comet (single-cell gel electrophoresis) assay of DNA damage in Hs68 cells was determined at 2h after incubation with OBC or OLP because of its high sensitivity. Both OBC and OLP significantly and dose-dependently increased DNA breakage while BC and LP had no effect. Inclusion of BHT during incubation of cells with 40 μM OBC or OLP partially inhibited (ca. 40%, p<.05) the extent of comet formation. Intriguingly, OBC and OLP neither induce lipid peroxidation in Hs68 cells (measured as thiobarbituric acid-reactive substances released into the medium) nor increased the intracellular level of reactive oxygen species. Although it is presently unclear about what degradation products are formed, this study has demonstrated that, when oxidized, BC and LP lead to oxidative damage to both purified DNA and cellular DNA. The results suggest that such damage may contribute to the adverse effects of β-carotene reported in recent clinical studies and caution that it is important to prevent oxidation of BC and LP for human uses such as in supplemental studies.     

Activation of p53-p21 is closely associated with the acquisition of resistance to apoptosis caused by β1-integrin silencing in head and neck cancer cells

The issue of whether aberrant expression of β1-integrin is associated with cancer progression and development of resistance to cytotoxic therapy is of considerable interest. Studies to date have shown that the anchorage-independent survival of cancer is attributed, in part, to epithelial-to-mesenchymal transition (EMT). Here, we have reported a novel alternative mechanism of anchorage-independent survival of cancer cells. Cell lines derived from head and neck cancer patients (AMC-HN-3 and AMC-HN-9) and the well-known EMT cancer cell line, MDA-MB231, were examined. The EMT features of AMC-HN-9 cells were comparable to those of MDA-MB231, whereas AMC-HN-3 cells showed no EMT characteristics. Although the pattern and degree of β1-integrin expression were similar in all three cell lines, sensitivities of the cells to β1-integrin knockdown with small interfering RNA (siRNA) were different. Cancer cells with no EMT features underwent cell death to a more significant extent following β1-integrin silencing than those with EMT. Intriguingly, we observed reactive activation of the p53-p21 pathway after β1-integrin silencing in AMC-HN-9 cells lacking an apparent cell death response. Simultaneous knockdown of wild-type p53 and β1-integrin in this cell line promoted cell death. Our data collectively indicate that β1-integrin-related cell death is closely associated with EMT phenotypes and activation of the p53-p21 pathway is partly involved in the acquisition of resistance to apoptosis induced by β1-integrin silencing. Further clarification of the mechanisms underlying p53 integration with β1-integrin signaling may facilitate the development of novel anti-cancer strategies.