Induction of apoptosis by Meretrix lusoria through reactive oxygen species production, glutathione depletion, and caspase activation in human leukemia cells

Bioactive Peptides from Meretrix lusoria Enzymatic Hydrolysate as a Potential Treatment for Obesity in db/db Mice

Obesity is acknowledged as a significant risk factor for cardiovascular disease, often accompanied by increased inflammation and diabetes. Bioactive peptides derived from marine animal proteins show promise as safe and effective anti-obesity agents by regulating adipocyte differentiation through the AMPK signaling pathway. Therefore, this study aims to investigate the anti-obesity and anti-diabetic effects of bioactive compounds derived from a Meretrix lusoria Protamex enzymatic hydrolysate (MLP) fraction (≤1 kDa) through a 6-week treatment (150 mg/kg or 300 mg/kg, administered once daily) in leptin receptor-deficient db/db mice. The MLP treatment significantly decreased the body weight, serum total cholesterol, triglycerides, and LDL-cholesterol levels while also exhibiting a beneficial effect on hepatic and serum marker parameters in db/db mice. A histological analysis revealed a reduction in hepatic steatosis and epididymal fat following MLP treatment. Furthermore, poor glucose tolerance was improved, and hepatic antioxidant enzyme activities were elevated in MLP-treated mice compared to db/db control mice. Western blot analysis showed an increased expression of the AMPK protein after MLP treatment. In addition, the expression of lipogenic genes decreased in db/db mice. These findings indicate that bioactive peptides, which are known to regulate blood glucose levels, lipid metabolism, and adipogenesis, could be beneficial functional food additives and pharmaceuticals.

Induction of Apoptosis by an Extract of Persian Gulf Marine Mollusc, Turbo Coronatus through the Production of Reactive Oxygen Species in Mouse Melanoma Cells

Objective: A variety of approaches such as surgery, chemotherapy, radiotherapy, hormonal therapy and immunotherapy are used to treat melanomas, but unfortunately in most case, the response is very weak and often side effects are serious. This study concerns selective toxicity of an extract of Turbo coronatus on cells and mitochondria from a syngeneic mouse model of melanoma. Methods: Cells and mitochondria isolated from extra tumoral and melanoma tissues were exposed toa T. coronatus crude extract and fractions obtained by gel-filtration chromatography and assayed for mitochondrial and cellular parameters. Result: Crude extract (375, 750 and 1,500 μg/ml) and fraction 1; F1; (275, 550 and 1100 μg/ml) of T. coronatus extract induced a significant (p<0.05) increase of the reactive oxygen species (ROS) level, swelling of mitochondria, collapse of mitochondrial membrane potential (MMP), release of cytochrome c and caspase-3 activation only in the mitochondria and cells obtained from melanoma but not extra tumoral tissues. In addition, the F1 fraction decreased the percentage of viable cells and induced apoptosis in melanoma cells. Conclusion: For the first time we could demonstrate that the F1 fraction of a T. coronatus extract, selectively induces ROS mediated cytotoxicity by directly targeting mitochondria in melanoma tissues and it may be a suitable candidate for novel drug treatment of malignant melanomas.

The Protective Effects of Clams on Hypercholesterolemia in Late-Stage Triple-Transgenic Alzheimer's Diseased Mice Hearts

To investigate a high cholesterol diet in Alzheimer’s disease (AD) mice, they were fed with (2% cholesterol) in five groups with a control group, AD mice group, AD mice plus Meretrix lusoria group, AD mice plus Geloina eros group, and, AD mice plus Corbicula fluminea group for three months, and treated with the fatty acid profiles of clams by gas chromatography (GC). The results showed that treatment with clams for three months reduced Fas/L and Caspase-3 in the Meretrix lusoria and Geloina eros groups, but Fas-associated death domain (FADD) and Caspase-8 were strongly reduced in the Geloina eros group. For the mitochondria-dependent apoptotic pathway, the reduction of apoptosis proteins were observed in the hearts of clams-treated AD mice. BAK and Caspase-9 was reduced in the Meretrix lusoria group, but Caspase-3 and Cytochrome-c were reduced in Geloina eros group. Enhancement of survival proteins p-AKT, p-IGF1R, p-PI3K, Bcl-XL, Bcl2, and the longevity SIRT1 signaling proteins, p-AMPK-α, SIRT1, PGC1-α, p-FOXO3 were observed in clams-treated mice and even more strongly enhanced in the Meretrix lusoria, Geloina eros and Corbicula fluminea groups. This study observed that the ingestion of clams caused a reduction of apoptosis proteins and enhancement of survival and SIRT1 signaling proteins in the hearts.

Cellular mechanism of resistance of human colorectal adenocarcinoma cells against apoptosis-induction by Russell's Viper venom l-amino acid oxidase (Rusvinoxidase)

The present study highlights the cellular mechanism of resistance in human adenocarcinoma (Colo-205) cells against apoptosis induction by Rusvinoxidase, an l-amino acid oxidase purified from Russell's Viper venom (RVV). The significantly lower cytotoxicity as well as apoptotic activity of Rusvinoxidase towards Colo-205 cells (compared to MCF-7 breast cancer cells) is correlated with lower depletion of cellular glutathione content and increased down-regulation of catalase activity of Colo-205 cells following Rusvinoxidase treatment. Exposure to Rusvinoxidase subsequently diminished reactive oxygen species (ROS) production and failed to impair mitochondrial membrane potential, resulting in apoptosis induction resistance in Colo-205 cells. Further, higher expression levels of caspase 8, compared to caspase 9, indicate that Rusvinoxidase preferentially triggers the extrinsic pathway of apoptosis in Colo-205 cells. A time-dependent lower ratio of the relative expression of Bax and Bcl-xL (pro- and anti-apoptotic proteins) in Colo-205 cells, compared to our previous study on MCF-7 cells, unambiguously supports a higher cellular resistance mechanism in Colo-205 cells against Rusvinoxidase-induced apoptosis.

Hard clam extracts induce atypical apoptosis in human gastric cancer cells

Hard clams (HCs) are a nutritionally high-quality and popular seafood, and are established to be a potent antitumor food. The aim of the present study was to determine whether HC extracts induce apoptosis in the human gastric cancer cell line, AGS. In contrast with previously reported methods of extraction, crude extracts of HC were obtained by freezing and thawing and by a method free of hot water or organic solvents. The composition, quality and properties of the HC extracts were demonstrated to be stable since the extracts that were evaluated by capillary electrophoresis and HPLC analysis at different timepoints were similar. HC extracts also have an inhibitory effect against the survival of AGS cells. Treatment with HC extracts induced a marked sub-G1 DNA peak and reduced the expression of the anti-apoptotic genes BIRC5 and KPNA2. However, hallmarks of classical apoptosis such as DNA fragmentation and apoptotic body formation were not observed, indicating atypical apoptosis. Furthermore, it was revealed that HC extracts interrupted cell cycle progression in AGS cells through altered expression of six cell cycle-associated genes: CDC20, KPNA2, BIRC5, ANAPC2, CDKN1A and RB1. The present findings suggest that HC may contribute to a novel future anticancer agent.

Apoptosis induction in human breast cancer (MCF-7) cells by a novel venom L-amino acid oxidase (Rusvinoxidase) is independent of its enzymatic activity and is accompanied by caspase-7 activation and reactive oxygen species production

We report the elucidation of a mechanism of apoptosis induction in breast cancer (MCF-7) cells by an L-amino acid oxidase (LAAO), Rusvinoxidase, purified from the venom of Daboia russelii russelii. Peptide mass fingerprinting analysis of Rusvinoxidase, an acidic monomeric glycoprotein with a mass of ~57 kDa, confirmed its identity as snake venom LAAO. The enzymatic activity of Rusvinoxidase was completely abolished after two cycles of freezing and thawing; however, its cytotoxicity toward MCF-7 cells remained unaffected. Dose- and time-dependent induction of apoptosis by Rusvinoxidase on MCF-7 cells was evident from changes in cell morphology, cell membrane integrity, shrinkage of cells and apoptotic body formation accompanied by DNA fragmentation. Rusvinoxidase induced apoptosis in MCF-7 cells by both the extrinsic (death-receptor) and intrinsic (mitochondrial) signaling pathways. The former pathway of apoptosis operated through activation of caspase-8 that subsequently activated caspase-7 but not caspase-3. Rusvinoxidase-induced intrinsic pathway of apoptosis was accompanied by a time-dependent depolarization of the mitochondrial membrane through the generation of reactive oxygen species, followed by a decrease in cellular glutathione content and catalase activity, and down-regulation of expression of anti-apoptotic proteins Bcl-XL and heat-shock proteins (HSP-90 and HSP-70). Rusvinoxidase treatment resulted in increase of the pro-apoptotic protein Bax, subsequently leading to the release of cytochrome c from mitochondria to the cytosol and activating caspase-9, which in turn stimulated effector caspase-7. Rusvinoxidase at a dose of 4 mg/kg was non-toxic in mice, indicating that it may be useful as a model for the development of peptide-based anticancer drugs.

Extraction, purification and antitumor activity of a water-soluble polysaccharide from the roots of Polygala tenuifolia

One polysaccharide PTP was isolated and purified from the roots of Polygala tenuifolia. It consisted of galactose, glucose and galactose in the ratio of 3.1:3.7:2.5, and a small amount of rhamnose, mannose and xylose. 17 general amino acids were identified to be components of the protein-bound polysaccharide analyzed by automatic amino acid analyzer. In order to test the anti-cancer activity of PTP, we investigated its effect against the growth of human ovarian cancer cells SKOV3 in vitro and in ovarian cancer rats. The intracellular reactive oxygen species (ROS) and glutathione (GSH) in SKOV3 cells following PTP treatment were also quantified to explore the possible mechanism underlying the antitumor activity of the polysaccharide. The result showed that PTP is effective on inhibiting the proliferation of SKOV3 cells in a concentration-dependent manner. Furthermore, treatment with PTP caused a rapid depletion of intracellular GSH content and accumulation of intracellular ROS, thus resulting in the apoptosis, which may prove to be a pivotal mechanism for its cancer protection action. In addition, a significant tumor growth inhibition effect was observed in nude mice after PTP administration for 7 weeks. All above indicated PTP could be beneficial towards ovarian cancer therapy.

Barakol-induced apoptosis in P19 cells through generation of reactive oxygen species and activation of caspase-9

ETHNOPHARMACOLOGICAL RELEVANCE

Barakol, an anxiolytic agent isolated from Senna siamea leaves which has been traditionally used for producing natural sleep, has been described as toxic to patients.

AIM OF THE STUDY

The aim of current study was to investigate the molecular mechanism of barakol-induced toxicity in mouse embryonal carcinoma P19 cell model.

MATERIALS AND METHODS

XTT assay was used to determine cell viability in P19 cells treated with barakol. Apoptotic cells were detected by Hoechst 33342 staining. Intracellular reactive oxygen species (ROS) generation was analyzed by flow cytometry using a fluorescent dye, DCFH-DA. Detection of apoptotic protein expression in P19 cells was performed by Western blot analysis. Caspase-9 activity was measured using a fluorescent immunosorbent enzyme assay kit.

RESULTS

Treatment with barakol decreased cell viability in a concentration- and time-dependent manner with an IC(50) value of 1.5mM in 24-h treated cells. A Hoechst 33342 assay revealed that barakol cytotoxicity was due to a significant increase in the number of apoptotic cells. Different scavengers to characterize ROS were utilized and revealed that hydroxyl radicals played a major role in ROS-induced apoptosis in barakol-treated cells. Western blot analysis demonstrated that barakol-induced apoptosis was mediated by the increase in expression ratio of Bax/Bcl-2. Furthermore, increase in caspase-9 activity after exposure to barakol for 24h was also observed. Pretreatment of cells with N-acetyl-l-cysteine (NAC) attenuated intracellular ROS generation, the Bax/Bcl-2 protein expression, and apoptosis.

CONCLUSIONS

The mechanism of barakol-mediated toxicity in P19 cells is mainly associated with the ROS generation, followed by the imbalance of the Bax/Bcl-2 ratio, and caspase-9 activation leading to apoptotic cell death. Pretreatment of cells with NAC could antagonize the toxicity produced by barakol.

Induction of apoptosis by [8]-shogaol via reactive oxygen species generation, glutathione depletion, and caspase activation in human leukemia cells

Ginger, the rhizome of Zingiber officinale , is a traditional medicine with a carminative effect and antinausea, anti-inflammatory, and anticarcinogenic properties. This study examined the growth inhibitory effects of [8]-shogaol, one of the pungent phenolic compounds in ginger, on human leukemia HL-60 cells. It demonstrated that [8]-shogaol was able to induce apoptosis in a time- and concentration-dependent manner. Treatment with [8]-shogaol caused a rapid loss of mitochondrial transmembrane potential, stimulation of reactive oxygen species (ROS) production, release of mitochondrial cytochrome c into cytosol, and subsequent induction of procaspase-9 and procaspase-3 processing. Taken together, these results suggest for the first time that ROS production and depletion of glutathione that contributed to [8]-shogaol-induced apoptosis in HL-60 cells.

Anti-tumour effects of HL-37, a novel anthracene derivative, in-vivo and in-vitro

Many anthracene derivatives possess excellent anti-tumour activity and are extensively used clinically as anti-tumour agents. However, their clinical use is frequently limited by emergence of multidrug resistance (MDR) in tumour cells. Therefore, new agents with the ability to overcome MDR are needed for cancer treatment. HL-37, a novel anthracene derivative, exhibited potent anti-cancer activity in both drug-sensitive (K562) and multidrug-resistant (K562/DOX) leukaemia cells. Mechanistically, we found that HL-37 was neither a substrate nor an inhibitor of P-glycoprotein (P-gp) and could overcome apoptotic resistance via up-regulation of p53 protein and down-regulation of Bcl-xL protein. In addition, HL-37 also induced K562/DOX cell apoptosis and a decrease in G0/G1 phase. Moreover, reduction of mitochondrial membrane potential, release of cytochrome c and an increased expression of cleaved protein fragment of caspase-3, caspase-9 and caspase-8 were also observed. Importantly, HL-37 was found to be better tolerated and more effective at inhibiting tumour growth than bisantrene in a xenograft mouse model.

6-Shogaol induces apoptosis in human colorectal carcinoma cells via ROS production, caspase activation, and GADD 153 expression

Ginger, the rhizome of Zingiber officinale, is a traditional medicine with anti-inflammatory and anticarcinogenic properties. This study examined the growth inhibitory effects of the structurally related compounds 6-gingerol and 6-shogaol on human cancer cells. 6-Shogaol [1-(4-hydroxy-3-methoxyphenyl)-4-decen-3-one] inhibits the growth of human cancer cells and induces apoptosis in COLO 205 cells through modulation of mitochondrial functions regulated by reactive oxygen species (ROS). ROS generation occurs in the early stages of 6-shogaol-induced apoptosis, preceding cytochrome c release, caspase activation, and DNA fragmentation. Up-regulation of Bax, Fas, and FasL, as well as down-regulation of Bcl-2 and Bcl-X(L )were observed in 6-shogaol-treated COLO 205 cells. N-acetylcysteine (NAC), but not by other antioxidants, suppress 6-shogaol-induced apoptosis. The growth arrest and DNA damage (GADD)-inducible transcription factor 153 (GADD153) mRNA and protein is markedly induced in a time- and concentration-dependent manner in response to 6-shogaol.

Mitochondrial alterations in human gastric carcinoma cell line

We compared mitochondrial function, morphology, and proteome in the rat normal gastric cell line RGM-1 and the human gastric cancer cell line AGS. Total numbers and cross-sectional sizes of mitochondria were smaller in AGS cells. Mitochondria in AGS cells were deformed and consumed less oxygen. Confocal microscopy indicated that the mitochondrial inner membrane potential was hyperpolarized and the mitochondrial Ca(2+) concentration was elevated in AGS cells. Interestingly, two-dimensional electrophoresis proteomics on the mitochondria-enriched fraction revealed high expression of four mitochondrial proteins in AGS cells: ubiquinol-cytochrome c reductase, mitochondrial short-chain enoyl-coenzyme A hydratase-1, heat shock protein 60, and mitochondria elongation factor Tu. The results provide clues as to the mechanism of the mitochondrial changes in cancer at the protein level and may serve as potential cancer biomarkers in mitochondria.