Atractylenolide III induces apoptosis by regulating the Bax/Bcl-2 signaling pathway in human colorectal cancer HCT-116 Cells in vitro and in vivo

Atractylodes is the dry root of atractylodes macrocephala koidz and has been commonly used as a traditional Chinese medicine (TCM). Atractylenolide III, a main component of atractylodes, has displayed significant effects on anti-inflammation and anticancer. However, the effects of atractylenolide III on growth inhibition and apoptosis induction in colon cancer remain unclear. The results showed that atractylenolide III significantly inhibited the cell growth and induce cellular apoptosis in HCT-116 cells in a concentration dependence manner in vitro. Mechanistic studies further showed that atractylenolide III could regulate the Bax/Bcl-2 apoptotic signaling pathway through promoting the expression of proapoptotic related gene/proteins Bax, caspase-9 and caspase-3 but inhibiting the expression of antiapoptotic related gene/protein Bcl-2 in HCT-116 cells. Furthermore, atractylenolide III also significantly inhibited the tumor growth of HCT-116 tumor xenografts bearing in nude mice through inducing apoptosis by upregulation of the expressions of Bax, cleaved caspase-3 and p53 but downregulation of the expressions of Bcl-2 in HCT-116 tumor tissues in vivo. The studies may provide the scientific rationale for the understanding of the anticancer effect of atractylenolide III. Therefore, atractylenolide III may have the potential to be developed as a promising novel anticancer agent for the treatment of colorectal cancer clinically.

The effects of L-carnitine on renal function and gene expression of caspase-9 and Bcl-2 in monosodium glutamate-induced rats

BACKGROUND

Monosodium glutamate (MSG) is frequently consumed as a flavor enhancer or food additive. Possible damages induced by MSG effects on some organs have been stated in experimental animal models. The aim of the present study was to evaluate the protective effects of L-carnitine (L-ca) on the renal tissue in MSG-Induced Rats.

METHODS

In this regard, 60 male rats were randomly divided into six groups (n = 10/each): 1 (Control); 2 (sham); 3 (L-carnitine 200 mg/kg b.w); 4 (MSG 3 g/kg b.w); 5 (MSG + L-carnitine 100 mg/kg); and 6 (MSG + L-carnitine 200 mg/kg). After 6 months, the rats were sacrificed, the blood sample collected and the kidneys harvested for evaluation of biochemical analytes, genes expression, and histopathological changes.

RESULTS

MSG significantly increased the serum level of MDA, BUN, creatinine, uric acid and renal Caspase-9, NGAL and KIM-1 expression, but it decreased the serum activity also renal expression of SOD, catalase, GPX, and Bcl-2 expression compared to the control group. Treatment with L-ca significantly reduced the serum BUN, creatinine, uric acid and MDA level and increased catalase, GPX and SOD compared to the MSG group. However, only administration of L-ca 200 significantly decreased the caspase-9, NGAL and KIM-1; also, it increased the Bcl-2 expression in the kidney compared to the MSG group.

CONCLUSIONS

Our findings indicated that L-carnitine had a major impact on the cell protection and might be an effective therapy in ameliorating the complications of the kidney induced by MSG via its antioxidant and anti-apoptotic properties.

The soluble VEGF receptor sFlt-1 contributes to endothelial dysfunction in IgA nephropathy

Endothelial injury is a common manifestation in IgA nephropathy (IgAN). After the previous identification of the upregulated soluble fms-like tyrosine kinase-1 (sFlt-1) correlated with endothelial injury in IgAN, in the present study, we further explored the role of sFlt-1 in endothelial injury in IgAN. We enrolled 72 patients with IgAN and detected the sFlt-1 levels. The polymeric IgA1 (pIgA1) complexes were isolated from the pooled plasma samples of another 10 patients with IgAN. Apoptosis proteins were detected in cultured human umbilical vein endothelial cells (HUVECs) with the stimulation of recombinant sFlt-1 or the caspase-9 inhibitor Z-LEHD-FMK. We identified there were positive correlations between sFlt-1 and IgA-IgG complex as well as vWF levels in patients with IgAN. The sFlt-1 levels in HUVECs were significantly upregulated by pIgA1 complex derived from IgAN patients in a concentration-dependent manner. The proliferation ability of HUVECs was damaged when stimulated with sFlt-1 protein in a time- and dose- dependent manner. And the apoptosis rate was up-regulated significantly as the stimulation concentrations of sFlt-1 increased. We found sFlt-1 challenge could significantly increase the expression of vWF. In addition, sFlt-1 increased the levels of caspase-9, caspase-3, Bax and mitochondrial membrane potential; facilitated the release of cytochrome C from mitochondria to cytoplasma. In contrast, Z-LEHD-FMK attenuated high sFlt-1-induced HUVECs apoptosis. In conclusion, our study demonstrated that sFlt-1 expression was up-regulated by the challenge of pIgA1 complex derived from patients with IgAN. Furthermore, increased sFlt-1 facilitated human umbilical vein endothelial cells apoptosis via the mitochondrial-dependent pathway.

MSP-4, an Antimicrobial Peptide, Induces Apoptosis via Activation of Extrinsic Fas/FasL- and Intrinsic Mitochondria-Mediated Pathways in One Osteosarcoma Cell Line

Osteosarcoma (OS) is a common malignant bone cancer. The relatively high density of a person's bone structure means low permeability for drugs, and so finding drugs that can be more effective is important and should not be delayed. MSPs are marine antimicrobial peptides (AMP) and natural compounds extracted from Nile tilapia (Oreochromis niloticus). MSP-4 is a part of the AMPs series, with the advantage of having a molecular weight of about 2.7-kDa and anticancer effects, although the responsible anticancer mechanism is not very clear. The goal of this study is to determine the workings of the mechanism associated with apoptosis resulting from MSP-4 in osteosarcoma MG63 cells. The study showed that MSP-4 significantly induced apoptosis in MG63 cells, with Western blot indicating that MSP-4 induced this apoptosis through an intrinsic pathway and an extrinsic pathway. Thus, a pretreatment system with a particular inhibitor of Z-IETD-FMK (caspase-8 inhibitor) and Z-LEHD-FMK (caspase-9 inhibitor) significantly attenuated the cleavage of caspase-3 and prevented apoptosis. These observations indicate that low concentrations of MSP-4 can help induce the apoptosis of MG63 through a Fas/FasL- and mitochondria-mediated pathway and suggest a potentially innovative alternative to the treatment of human osteosarcoma.

p53 activation by Ni(II) is a HIF-1α independent response causing caspases 9/3-mediated apoptosis in human lung cells

Hypoxia mimic nickel(II) is a human respiratory carcinogen with a suspected epigenetic mode of action. We examined whether Ni(II) elicits a toxicologically significant activation of the tumor suppressor p53, which is typically associated with genotoxic responses. We found that treatments of H460 human lung epithelial cells with NiCl2 caused activating phosphorylation at p53-Ser15, accumulation of p53 protein and depletion of its inhibitor MDM4 (HDMX). Confirming the activation of p53, its knockdown suppressed the ability of Ni(II) to upregulate MDM2 and p21 (CDKN1A). Unlike DNA damage, induction of GADD45A by Ni(II) was p53-independent. Ni(II) also increased p53-Ser15 phosphorylation and p21 expression in normal human lung fibroblasts. Although Ni(II)-induced stabilization of HIF-1α occurred earlier, it had no effect on p53 accumulation and Ser15 phosphorylation. Ni(II)-treated H460 cells showed no evidence of necrosis and their apoptosis and clonogenic death were suppressed by p53 knockdown. The apoptotic role of p53 involved a transcription-dependent program triggering the initiator caspase 9 and its downstream executioner caspase 3. Two most prominently upregulated proapoptotic genes by Ni(II) were PUMA and NOXA but only PUMA induction required p53. Knockdown of p53 also led to derepression of antiapoptotic MCL1 in Ni(II)-treated cells. Overall, our results indicate that p53 plays a major role in apoptotic death of human lung cells by Ni(II). Chronic exposure to Ni(II) may promote selection of resistant cells with inactivated p53, providing an explanation for the origin of p53 mutations by this epigenetic carcinogen.

Xanthohumol induces apoptosis in human malignant glioblastoma cells by increasing reactive oxygen species and activating MAPK pathways

The effect of the biologically active prenylated chalcone and potential anticancer agent xanthohumol (1) has been investigated on apoptosis of the T98G human malignant glioblastoma cell line. Compound 1 decreased the viability of T98G cells by induction of apoptosis in a time- and concentration-dependent manner. Apoptosis induced by 1 was associated with activation of caspase-3, caspase-9, and PARP cleavage and was mediated by the mitochondrial pathway, as exemplified by mitochondrial depolarization, cytochrome c release, and downregulation of the antiapoptotic Bcl-2 protein. Xanthohumol induced intracellular reactive oxygen species (ROS), an effect that was reduced by pretreatment with the antioxidant N-acetyl-L-cysteine (NAC). Intracellular ROS production appeared essential for the activation of the mitochondrial pathway and induction of apoptosis after exposure to 1. Oxidative stress due to treatment with 1 was associated with MAPK activation, as determined by ERK1/2 and p38 phosphorylation. Phosphorylation of ERK1/2 and p38 was attenuated using NAC to inhibit ROS production. After treatment with 1, ROS provided a specific environment that resulted in MAPK-induced cell death, with this effect reduced by the ERK1/2 specific inhibitor PD98059 and partially inhibited by the p38 inhibitor SB203580. These findings suggest that xanthohumol (1) is a potential chemotherapeutic agent for the treatment of glioblastoma multiforme.

An unfractionated fucoidan from Ascophyllum nodosum: extraction, characterization, and apoptotic effects in vitro

An unfractionated fucoidan was extracted from the brown alga Ascophyllum nodosum. Extraction of fucoidan from seaweed was carried out using an innovative low-chemical process. A combinational approach involving compositional analysis, HPAEC, IR analysis, GPC, and NMR was employed to elucidate the composition and structure of an unfractionated fucoidan from A. nodosum. This fucoidan is composed mainly of fucose (52.1%), and also galactose (6.1%), glucose (21.3%), and xylose (16.5%). Sulfate content was determined to be 19%. GPC data indicated a polydisperse fucoidan containing two main size fractions (47 and 420 kDa). NMR analyses revealed a fucoidan displaying broad, complex signals as expected for such a high molecular weight and heterogeneous polymer with resonances consistent with a fucoidan isolated previously from A. nodosum. The effects of fucoidan on the apoptosis of human colon carcinoma cells and fucoidan-mediated signaling pathways were also investigated. Fucoidan decreased cell viability and induced apoptosis of HCT116 colon carcinoma cells. Fucoidan treatment of HCT116 cells induced activation of caspases-9 and -3 and the cleavage of PARP, led to apoptotic morphological changes, and altered mitochondrial membrane permeability. These results detail the structure and biological activity of an unfractionated fucoidan from A. nodosum.

Lipid-soluble ginseng extract induces apoptosis and G0/G1 cell cycle arrest in NCI-H460 human lung cancer cells

This study was performed to elucidate the anticancer mechanism of a lipid-soluble ginseng extract (LSGE) by analyzing induction of apoptosis and arrest of cell cycle progression using the NCI-H460 human lung cancer cell line. Proliferation of NCI-H460 cells was potently inhibited by LSGE in a dose-dependent manner. The cell cycle arrest at the G0/G1 phase in NCI-H460 cells was induced by LSGE. The percentage of G0/G1 phase cells significantly increased, while that of S phase cells decreased after treatment with LSGE. The expression levels of cyclin-dependent kinase2 (CDK2), CDK4, CDK6, cyclin D3 and cyclin E related to G0/G1 cells progression were also altered by LSGE. In addition, LSGE-induced cell death occurred through apoptosis, which was accompanied by increasing the activity of caspases including caspase-8, caspase-9 and caspase-3. Consistent with enhancement of caspase activity, LSGE increased protein levels of cleaved caspase-3, caspase-8, caspase-9, and poly-ADP-ribose polymerase (PARP). These apoptotic effects of LSGE were inhibited by the pan-caspase inhibitor Z-VAD-fmk. These findings indicate that LSGE inhibits NCI-H460 human lung cancer cell growth by cell cycle arrest at the G0/G1 phase and induction of caspase-mediated apoptosis.

Effects of nicotine on apoptosis in human gingival fibroblasts

AIM

Cigarette smoke is a complex mixture of more than 4700 chemical compounds including free radicals and oxidants and it is a world widely known problem to health. Nicotine is the major compound of tobacco and known as the cause of gingivitis and periodontitis. It induces intracellular oxidative stress recognized as the important agent in the damage of biological molecules. The aim of this study is to clarify the cytotoxic pathway of nicotine in human gingival fibroblasts (HGFs).

METHODS

Human gingival fibroblasts stimulated by nicotine were used as an in vitro model. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect cell viability and reactive oxygen species (ROS) generation was assessed with 2,7-dichlorofluoroscein diacetate (DCF-DA). Morphological change was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) assay, stained with 4,6-diamidino-2-phenylindole (DAPI). To delineate the roles of extracellular signal-regulated kinase (ERK), P38 and c-Jun N-terminal kinase (JNK), Western blot and caspase-3 (CASP3) activity assay were performed.

RESULTS

Exposure of the human gingival fibroblasts to nicotine reduced cell viability by time and dose dependent and increased the generation of ROS. It also showed morphological evidence of increased apoptosis, resulted in transient activation of JNK and ERK concomitant with activation of P38, and stimulated apoptosis as evidenced by CASP3 activation and Poly ADP ribose polymerase (PARP) cleavage.

CONCLUSION

These results suggest that nicotine induces apoptosis through the ROS generation and CASP3 dependent pathways in HGFs.

Reduction in lipopolysaccharide-induced apoptosis of fibroblasts obtained from a patient with gingival overgrowth during nifedipine-treatment

OBJECTIVE

We have previously demonstrated that the mechanism of nifedipine (NIF)-induced gingival overgrowth is related to the observation that proliferation and cell cycle progression of gingival fibroblasts derived from NIF reactive patient (NIFr) are greater than those from NIF non-reactive patient (NIFn). Gingival overgrowth has also been reported to be a result of inhibited apoptosis of gingival fibroblasts. Apoptosis in fibroblasts is induced by lipopolysaccharide (LPS). Thus, we focused upon evaluating whether there is a difference in LPS-induced apoptosis between NIFn and NIFr.

METHODS

Both NIFn and NIFr were arrested in DMEM containing 0.5% FBS, stimulated by LPS, and assayed for apoptosis, cell cycle analysis, Western blotting, and caspase activity.

RESULTS

Compared to NIFn, the number of apoptotic cells was significantly decreased and the percentage of cells in S and G(2)/M phase was significantly increased in NIFr. The levels of Bax and cytochrome c proteins in NIFr were not up-regulated by LPS compared with NIFn. Both NIFn and NIFr displayed the following changes in protein expression: increased Bad, decreased Bcl-xL, and unchanged Bcl-2 and p53. Caspase-3 and -9 activities were significantly increased by LPS in NIFn but were unchanged in NIFr. Caspase-2 activity remained constant whilst caspase-8 activity significantly increased upon LPS treatment in both NIFn and NIFr.

CONCLUSION

Bad, Bax, cytochrome c, p53, and caspases-2, -3, -8, and -9 are pro-apoptotic proteins. Bcl-2 and Bcl-xL are anti-apoptotic proteins. Thus, the mechanism of NIF-induced gingival overgrowth might be related to decreased apoptosis in NIFr through a reduction of Bax, cytochrome c, and caspase-3 and -9.

Typhonium flagelliforme induces apoptosis in CEMss cells via activation of caspase-9, PARP cleavage and cytochrome c release: its activation coupled with G0/G1 phase cell cycle arrest

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Typhonium flagelliforme (TF), commonly known as 'rodent tuber' in Malaysia, is often used as traditional remedy for cancer, including leukemia.

AIM OF THE STUDY

We had previously identified morphologically that the linoleic acid rich fraction (DCM/F7) from the tubers of this plant induces selective anti-proliferative effects and apoptosis in CEMss cells. In this present study, we subjected the same DCM/F7 fraction to cell based activity analyses in order to determine the possible mechanism of cell death in leukemic CEMss cells in vitro.

MATERIALS AND METHODS

Extraction of Typhonium flagelliforme tuber has done and fractionation has been done by vacuum liquid column chromatography. The anti-proliferative activity was assayed using MTT and the apoptosis detection was done by Annexin V and DNA laddering assay. Colorimetric caspase assay and immunoblot analysis were employed to detect the expression of protein associated with cell death. Cell cycle analysis was done using flow cytometry.

RESULTS

We found that the cancer inhibitory effect of the DCM/F7 fraction in CEMss cells was 3 ± 0.08 μg/ml (IC(50)). An early apoptotic induction in CEMss cells was observed by Annexin V assay, which showed a clear dose-dependent DNA fragmentation being observed in gel electrophoresis at 10 and 20 μg/ml. The DCM/F7 fraction at 3 μg/ml significantly arrested CEMss cells at G0/G1 phase (p<0.05). A constant but increasing pattern-related Sub-G0/G1 index was observed between 12 and 72 h treatment. In relation to this, we further investigated the biochemical events leading to cell death and found that the DCM/F7 fraction increased the cellular levels of caspase-3 and -9 on treated cells. Our results indicated that cytochrome c from mitochondria into the cytosol increased gradually as the DCM/F7 concentration increases, which later lead to the subsequent cleavage of PARP in to 85kDa fragments. On the contrary, Bcl-2 protein was found to decrease concomitantly during treatment.

CONCLUSIONS

Collectively, results presented in this study demonstrated that the DCM/F7 fraction inhibited the proliferation of leukemia cells, leading to the programmed cell death, which was confirmed to be through the mitochondrial pathway.

Antifibrotic effects of ZK14, a novel nitric oxide-donating biphenyldicarboxylate derivative, on rat HSC-T6 cells and CCl4-induced hepatic fibrosis

AIM

To study the pharmacologic effect of ZK(14), a novel nitric oxide-donating biphenyldicarboxylate (DDB) derivative, on HSC-T6 cells and on CCl(4)-induced hepatic fibrosis.

METHODS

Inhibition of HSC-T6 cell growth by ZK(14) was evaluated by MTT assay. The effect of ZK(14) on the percentage of HSC-T6 cells undergoing apoptosis was measured using Annexin-V/PI double-staining and TUNEL assay. Mitochondrial membrane potential (MMP) and caspase activities were tested. Hepatic fibrosis was induced in Sprague-Dawley rats by intraperitoneal injection with 14% CCl(4). Rats with hepatic fibrosis were randomly divided into four groups: model control, ZK(14) (20 mg/kg), ZK(14) (10 mg/kg) and DDB (5 mg/kg). Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), hyaluronic acid (HA), type III collagen (PCIII), and nitric oxide (NO) were assessed, and liver samples were stained with hematoxylin-eosin. The NO level in cells treated with ZK(14) in vitro was also measured.

RESULTS

The effect of ZK(14) on HSC-T6 cell apoptosis was concentration- and time-dependent, with up to 50% of cells becoming apoptotic when exposed to 100 mumol/L ZK(14) for 18 h. ZK(14) treatment resulted in mitochondrial membrane depolarization and activation of caspases 3 and 9. At a dose of 20 mg/kg, ZK(14) significantly decreased serum transaminase (AST, ALT) activities and fibrotic index (HA, PCIII) levels and significantly inhibited fibrogenesis.

CONCLUSION

These data indicate that ZK(14), a novel NO-donating DDB derivative, promotes HSC-T6 apoptosis in vitro through a signaling mechanism involving mitochondria and caspase activation and it inhibits CCl(4)-induced hepatic fibrosis in vivo. The results suggest that ZK(14) has potential therapeutic value in the treatment of hepatic fibrosis.

Differential apoptotic response of human cancer cells to organoselenium compounds

PURPOSE

Selenium (Se) compounds are well known to inhibit cell proliferation and induce cell death in human cancer cells. Respective chemical forms of Se are intracellularly metabolized via complicated pathways, which target distinct molecules and exhibit varying degrees of anti-carcinogenicity in different cancer types; however, the precise mechanisms by which Se activates apoptosis remain poorly understood.

METHODS

The effects of Se compounds, Se-methylselenocysteine (MSC), selenomethionine (SeMet), and selenite on cell proliferation, apoptosis and its pathway in established human carcinoma cell lines (HSC-3, -4, A549, and MCF-7) were investigated. Cancer cells were treated with each Se compound during different periods. Cell apoptosis, caspase activity and ER stress markers were analyzed by flow cytometric or immunoblotting analysis, respectively.

RESULTS

We examined four cell lines for their sensitivity to MSC and SeMet in comparison with selenite. SeMet increased apoptotic cells in p53-positive A549 cells, whereas MSC increased apoptotic cells in p53-mutated HSC-3 cells. High activities of caspase-3, -8 and -9 were observed during apoptosis, and a pan-caspase inhibitor, z-VAD-fmk, rescued the cell viability of HSC-3 cells exposed to MSC. In addition, the occurrence of endoplasmic reticulum (ER) stress was suggested by the observation that levels of phosphorylated eIF2alpha and caspase-12 activity are increased in Se-treated cells. Selenite and MSC were accompanied with the concurrent reduction of phosphorylated Akt levels, and the inhibitory effects of these Se compounds on vascular endothelial growth factor expression were observed with identical patterns.

CONCLUSION

The present findings demonstrate that Se-induced apoptosis in carcinoma cells is basically a caspase-dependent process involving complicated mechanisms. Activation of both the intrinsic apoptotic pathway and ER stress pathway plays a major and concurrent role, while p53 activation seems to have only a functional role in SeMet.

Tuning of apoptosis-mediator gene transcription in HepG2 human hepatoma cells through an adenosine signal

Extracellular adenosine-induced apoptosis of HepG2 cells, a human hepatoma cell line, in a concentration (0.1-20mM)- and treatment (24-72h)-dependent manner by activating caspase-3, -8, and -9. In the gene expression assay using a DNA microalley, adenosine upregulated mRNAs for tumor necrosis factor (TNF), TNF receptor 1-associated death domain protein (TRADD), TNF related apoptosis-inducing ligand receptor 2 (TRAIL-R2), TRADD/receptor-interacting protein kinase 1 (RIPK1), Fas-associated death domain protein (FADD), and caspase-9, involving activation of caspase-8 and -9 followed by the effector caspase-3. The results of the present study suggest that adenosine induces HepG2 cell apoptosis by activating those caspases as a result from tuning apoptosis-mediator gene transcription.

Overexpression of Pygopus2 protects HeLa cells from vinblastine-induced apoptosis

Pygopus, a very important component of the Wnt signaling transcriptional complex, has multiple functions in both Wnt-dependent and -independent pathways. Human Pygopus2 (Pygo2) is expressed in many cancers and plays an important role in tumor growth. In the present study, we generated human carcinoma (HeLa) cell lines stably expressing Pygo2, which counteracts vinblastine- induced apoptosis. The anti-apoptotic function was determined by DNA fragmentation, sub-G1 appearance, loss of mitochondrial membrane potential (Deltapsim) and the activation of caspase-9 and caspase-3. In addition, we found that Pygo2 effectively blocks vinblastineinduced c-Jun and AP-1 activation, maintains the anti-apoptotic protein Bcl-2 in an unphosphorylated state, and thus can render cells resistant to apoptosis. However, Pygo2 does not alter the vinblastine-induced cell cycle changes. Here, we describe an anti-apoptotic activity exerted by Pygo2 through blocking activation of the JNK/AP-1 signaling pathway induced by vinblastine.

6-mercaptopurine (6-MP) induces p53-mediated apoptosis of neural progenitor cells in the developing fetal rodent brain

6-mercaptopurine (6-MP), a DNA-damaging agent, induces apoptosis of neural progenitor cells, and causes malformation in the fetal brain. The aim of the present study is to clarify the molecular pathway of 6-MP-induced apoptosis of neural progenitor cells in the fetal telencephalon of rats and mice. p53 protein is activated by DNA damage and induces apoptosis through either the intrinsic pathway involving the mitochondria or the extrinsic pathway triggered by death receptors. In this study, the expression of puma and cleaved caspase-9 proteins, which are specific intrinsic pathway factors, increased in the rat telencephalon after 6-MP treatment. 6-MP-induced apoptosis of neural progenitor cells was completely absent in p53-deficient mice. On the other hand, the expression of Fas protein, an extrinsic pathway factor, did not change throughout the experimental period in the rat telencephalon treated with 6-MP. The number of apoptotic neural progenitor cells was similar among Fas-mutated lpr/lpr and wild-type mice, suggesting that the Fas pathway does not play a significant role in 6-MP-induced apoptosis of neural progenitor cells. These results may suggest that the p53-mediated intrinsic pathway is essential for 6-MP-induced apoptosis of neural progenitor cells in the developing telencephalon of rats and mice.

P38 mitogen-activated protein kinase pathways are involved in the hypertrophy and apoptosis of cardiomyocytes induced by Porphyromonas gingivalis conditioned medium

The surrounding medium of periodontal pathogen Porphyromonas gingivalis (P. gingivalis) increased cardiomyocyte hypertrophy and apoptosis whereas Actinobaeillus actinomycetemcomitans and Prevotella intermedia had no effects. The purpose of this study is to clarify the role of p38 pathway in P. gingivalis conditioned medium-induced H9c2 myocardial cell hypertrophy and apoptosis. DNA fragmentation, cellular morphology, nuclear condensation, p38 protein products, and mitochondrial-dependent apoptotic related proteins in cultured H9c2 myocardial cell were measured by agarose gel electrophoresis, immunofluorescence, DAPI, and western blotting following P. gingivalis conditioned medium and/or pre-administration of SB203580 (p38 inhibitor). The p38 protein products and associated activities in H9c2 cells were both upregulated by P. gingivalis conditioned medium. P. gingivalis conditioned medium increased cellular sizes, DNA fragmentation, nuclear condensation, mitochondrial Bcl2-associated death promoter (Bad), cytosolic cytochrome c (cyt c), and the activated form of caspase-9 proteins in H9c2 cells. The increased cellular sizes, DNA fragmentation, nuclear condensation, Bad, cyt c, and caspase-9 activities of H9c2 cells treated with P. gingivalis conditioned medium were all significantly reduced after pre-administration of SB203580. Our findings suggest that the activity of p38 signal pathway may be initiated by P. gingivalis conditioned medium and further activate mitochondrial-dependent apoptotic pathways leading to cell death in cultured H9c2 myocardial cells.

High concentration simvastatin induces apoptosis in fibroblast-like synoviocytes from patients with rheumatoid arthritis

OBJECTIVE

We previously reported that 10 mg/day of simvastatin significantly reduced clinical scores of rheumatoid arthritis (RA) in patients with active RA with hypercholesterolemia. We have also reported that a certain pharmacological concentration of simvastatin, i.e., 0.05-0.1 microM, inhibits the production of interleukin 6 (IL-6) and IL-8 and the cell proliferation induced by tumor necrosis factor-alpha (TNF-alpha) in fibroblast-like synoviocytes (FLS) derived from patients with RA in vitro. We investigated other effects of simvastatin on FLS from the standpoint of cell viability and apoptosis.

METHODS

RA FLS were cultured with or without 0.05-50 microM simvastatin for 48 h. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was measured by flow cytometric analysis using propidium iodide and annexin-V. Caspase-3 and -9 activities were analyzed by colorimetric assays.

RESULTS

High concentrations of simvastatin, i.e., 1.0-50 microM, reduced cell viability and induced prominent apoptosis in FLS in a dose-dependent manner. The apoptosis induced by simvastatin was caspase-3- and caspase-9-dependent. These effects were completely reversed in the presence of mevalonic acid or geranylgeranyl-pyrophosphate, but not in the presence of farnesyl-pyrophosphate. Further, a geranylgeranyl transferase inhibitor and a RhoA kinase inhibitor mimicked the effect of simvastatin.

CONCLUSION

These data, together with our previous report, suggest that low (pharmacological range) and high concentrations of simvastatin affect FLS differently: (1) at a low concentration, it inhibits IL-6 and IL-8 production and the cell proliferation of FLS induced by TNF-alpha (2) at high concentrations, it induces apoptosis in FLS. Understanding this dose-dependent biphasic effect of simvastatin may prove important for its clinical applications in the treatment of RA.

Proteasomal inhibition and apoptosis regulatory changes in human isolated lymphocytes: The synergistic role of dopamine

Abnormal deposition of protein aggregates and increased susceptibility to apoptotic cell death may result from defects in the activity of the ubiquitin-proteasome system (UPS); neurotoxicity related to UPS defects seems to require dopamine to be fully expressed. The aim of this study was to investigate the pro-apoptotic effects caused by proteasomal activity inhibition, as well as the synergistic effect of dopaminergic stimulation in human lymphocytes isolated from healthy volunteers. Cells were incubated 20 h at 37 degrees C, with: (1) lactacystin, (2) increasing concentrations of dopamine or (3) mixture of dopamine and lactacystin. Activities of proteasome 20S and pro-apoptotic caspases-3 and -9 and levels of anti-apoptotic Bcl-2 were measured with fluorimetric or immunochemical assays, while a "DNA diffusion" assay was used to determine the apoptosis. Incubation of lymphocytes with lactacystin, which caused reduction of proteasomal activity, was associated with activation of caspases. A clear, dose-dependent reduction of proteasomal activity was also seen in the presence of increasing doses of dopamine, which was accompanied by a slight dose-dependent increase of caspases activities and Bcl-2 levels. Both effects on proteasome and caspase activities were enhanced when cells were simultaneously exposed to lactacystin and elevated concentrations of dopamine. Apoptosis was detected in all treated samples, but not in controls, without significant differences among the treatment groups; however, the association of dopamine and lactacystin induced a clear reduction in the number of cells being analyzed, pointing to marked cytotoxicity. Our data confirm the potentiation of cytotoxicity related to proteasome inhibition, in the presence of dopaminergic stimulation.

Differential involvement of mitochondria during ursolic acid-induced apoptotic process in HaCaT and M4Beu cells

Ursolic acid (UA) is a pentacyclic triterpenoid compound which exists widely in nature and is known to have a pleitropic biological activity profile. For the last few decades, extensive work has been carried out to establish its biological activities and pharmacological actions. It is described as a promising chemopreventive agent with an antiproliferative effect on cancer cells that stems from its ability to induce apoptosis. We investigated and compared the role played by mitochondria during the apoptotic process induced by UA in human HaCaT-derived keratinotic cells and M4Beu human melanoma cells. In both cell lines, UA induced significant caspase-3 activation, the downstream central effector of apoptosis. Subsequent JC-1/TOTO-3 double staining clearly demonstrated that UA induces strong mitochondrial-transmembrane potential collapse in M4Beu cells, while mitochondria from HaCaT-treated cells remain largely unstimulated. This was confirmed by Western blot analysis, which revealed a Bax/Bcl-2-balance change in favor of Bax, the proapoptotic member, in UA-treated M4Beu cells. It can be concluded that UA induces apoptosis in M4Beu through the mitochondrial pathway, while other mechanisms are activated in the case of HaCaT cells.

Undecylprodigiosin selectively induces apoptosis in human breast carcinoma cells independent of p53

Undecylprodigiosin (UP) is a bacterial bioactive metabolite produced by Streptomyces and Serratia. In this study, we explored the anticancer effect of UP. Human breast carcinoma cell lines BT-20, MCF-7, MDA-MB-231 and T47D and one nonmalignant human breast epithelial cell line, MCF-10A, were tested in this study. We found that UP exerted a potent cytotoxicity against all breast carcinoma cell lines in a dose- and time-dependent manner. In contrast, UP showed limited toxicity to MCF-10A cells, indicating UP's cytotoxic effect is selective for malignant cells. UP's cytotoxic effect was due to apoptosis, as confirmed by positive TUNEL signals, annexin V-binding, caspase 9 activation and PARP cleavage. Notably, UP-induced apoptosis was blocked by the pan-caspase inhibitor z-VAD.fmk, further indicating the involvement of caspase activity. Moreover, UP caused a marked decrease of the levels of antiapoptotic BCL-X(L), Survivin and XIAP while enhancing the levels of proapoptotic BIK, BIM, MCL-1S and NOXA, consequently favoring induction of apoptosis. Additionally, we found that cells with functional p53 (MCF-7, T47D) or mutant p53 (BT-20, MDA-MB-231) were both susceptible to UP's cytotoxicity. Importantly, UP was able to induce apoptosis in MCF-7 cells with p53 knockdown by RNA interference, confirming the dispensability of p53 in UP-induced apoptosis. Overall, our results establish that UP induces p53-independent apoptosis in breast carcinoma cells with no marked toxicity to nonmalignant cells, raising the possibility of its use as a new chemotherapeutic drug for breast cancer irrespective of p53 status.

Acute ammonia neurotoxicity in vivo involves increase in cytoplasmic protein P53 without alterations in other markers of apoptosis

Acute intoxication with large ammonia doses leads to activation of NMDA receptors in the brain, resulting in oxidative stress and disturbance of mitochondrial function. Altered mitochondrial function is a crucial step in some mechanisms of cellular apoptosis. This study assesses whether ammonia intoxication in vivo leads to induction of apoptotic markers such as permeability transition pore (PTP) formation, caspase-3, and caspase-9 activation, changes in p53 protein, or cytochrome c release. Acute ammonia intoxication did not affect caspase-9 or caspase-3 activities. The mitochondrial membrane potential also remained unaltered in non-synaptic brain mitochondria after injection of ammonia, indicating that ammonia did not induce PTP formation in brain in vivo. The nuclear level of p53 did not change, whereas its cytoplasmic level increased approximately two-fold. In agreement with the theory that translocation of the p53 from cytosol to nuclei is an essential step for induction of apoptosis we did not find apoptotic nuclei in brain of rats injected with ammonia. This supports the idea that ammonia neurotoxicity does not involve apoptosis and points to impaired p53 transfer from cytoplasm to nuclei as a possible preventer of apoptosis. We did not find any release of cytochrome c from mitochondria to cytosol after ammonia injection. Cytochrome c content was significantly reduced (30%) in brain mitochondria from rats injected with ammonia. This decrease may contribute to the reduced state 3 respiration, decreased respiratory control index, and disturbances in the mitochondrial electron transport chain in brain mitochondria from rats injected with ammonia.

Role of mitochondria in silica-induced apoptosis of alveolar macrophages: inhibition of apoptosis by rhodamine 6G and N-acetyl-L-cysteine

Induction of apoptosis by silica in alveolar macrophages (AM) may be a critical step in silica-induced lung injury and pulmonary fibrosis. This study investigated the mechanism(s) through which silica induces apoptosis in AM and their production of proinflammatory cytokines. Using N-acetyl-L-cysteine (NAC) for glutathione (GSH) synthesis and removal of reactive oxygen species (ROS), and rhodamine 6G (R6G) to inhibit the mitochondrial-dependent function, this study found that silica-induced apoptosis of rat AM in primary culture is mitochondria dependent and exhibits a mechanism involving ROS generation, increased mitochondrial release of cytochrome c, and the activation of caspase 9, but not caspase 8, activity. Silica-induced apoptosis was accompanied by a lowering of intracellular and mitochondrial GSH (mGSH) and was blocked by pretreatment of cells with NAC or R6G. When cells were exposed to silica and then treated with either NAC or R6G, silica-induced apoptosis was not affected by the blocking agent. In addition, R6G, which inhibited cellular ATP production and mitochondrial ROS generation, had no effect on apoptosis induced by exogenous hydrogen peroxide or superoxide. Pretreatment of cells with NAC or R6G also inhibited silica-induced production of interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha, but the inhibition of these cytokines with agents known to block their secretion did not protect cells from silica-induced apoptosis. Data indicate that silica-induced apoptosis is mediated through mitochondrial generation of ROS, which may be inhibited by pretreatment of cells with R6G that prevents ROS generation, or with NAC that maintains a high level of mGSH. The secretion of IL-1beta and TNF-alpha by silica-exposed AM was markedly inhibited by NAC and R6G, suggesting that the production of these cytokines is also ROS dependent.

Anti-tumor potential of 15,16-dihydrotanshinone I against breast adenocarcinoma through inducing G1 arrest and apoptosis

Chemotherapeutic drugs are usually designed to induce cancer cell death via cell cycle arrest and/or apoptosis pathways. In this study, we used the chemical drug 15,16-dihydrotanshinone I (DHTS) to inhibit breast cancer cell proliferation and tumor growth, and investigate the underlying molecular mechanisms. Human breast cancer cell lines MCF-7 and MDA-MB-231 were both used in this study, and DHTS was found to significantly decrease cell proliferation by a dose-dependent manner in both cells. Flow cytometry indicated that DHTS induced G1 phase arrest in synchronous MCF-7 and MDA-MB-231 cells. When analyzing the expression of cell cycle-related proteins, we found that DHTS reduced cyclin D1, cyclin D3, cyclin E, and CDK4 expression, and increased CDK inhibitor p27 expression in a dose-dependent manner. In addition, DHTS inhibited the kinase activities of CDK2 and CDK4 by an immunocomplex kinase assay. In addition, DHTS also induced apoptosis in both cells through mainly mitochondrial apoptosis pathways. We found that DHTS decreased the anti-apoptotic protein Bcl-xL level and increased the loss of mitochondria membrane potential and the amount of cytochrome c released. Moreover, DHTS activated caspase-9, caspase-3, and caspase-7 and caused cell apoptosis. The fact that DHTS-induced apoptosis could be blocked by pretreating cells with pan-caspase inhibitor confirmed that it is mediated through activation of the caspase-3-dependent pathway. In a nude mice xenograft experiment, DHTS significantly inhibited the tumor growth of MDA-MB-231 cells. Taken together, these results suggest that DHTS can inhibit human breast cancer cell proliferation and tumor growth, and might have potential chemotherapeutic applications.

Differential regulation of Akt, caspases and MAP kinases underlies smooth muscle cell apoptosis during aortic remodelling in SHR treated with amlodipine

BACKGROUND AND PURPOSE

The regression of aortic hypertrophy is initiated by a transient wave of smooth muscle cell (SMC) apoptosis in spontaneously hypertensive rats (SHR) treated with antihypertensive drugs, although the molecular pathways remain unclear.

EXPERIMENTAL APPROACH

Enzymes involved in apoptosis regulation were examined daily during onset aortic remodelling in SHR treated with amlodipine (20 mg kg(-1) day(-1)).

KEY RESULTS

Significant reduction of aortic SMC number occurred by day 3 of amlodipine, reaching -13% at 28 days, followed by a significant regression of medial hypertrophy by day 5, reaching -13% at 28 days. ISOL-positive (apoptotic) SMC nuclei increased by 4.6-fold between days 2 and 4, in temporal correlation with the activation of caspase-8 (2.7-fold) at day 2 only, caspase-3 at days 3 and 4 (1.7-fold) and caspase-9 at day 3 only (3.1-fold). Akt phosphorylation, a pro-survival pathway, was reduced prior to apoptosis at day 1 (-52%) and until day 3. During the first 6 days of amlodipine treatment, significant reduction in phosphorylation of mitogen-activated protein (MAP) kinases was transient for p38 (-46% at day 3 only) but continuous for ERK1/2 after 3 days (-40%), and for JNK after 4 days (>-50%).

CONCLUSIONS AND IMPLICATIONS

Amlodipine inhibition of Akt occurred prior to and during SMC apoptosis induction, a process mediated by the early activation of caspase-8 followed by caspase-9 and -3 and associated with MAP kinase inhibition. These findings provide insights about the molecular pathways underlying SMC apoptosis leading to vascular remodelling during amlodipine treatment of hypertension.

Stabilization of mitochondrial membrane potential and improvement of neuronal energy metabolism by Ginkgo biloba extract EGb 761

Ginkgo biloba extract EGb 761 has been used for many years to treat age-related cognitive disorders including Alzheimer's disease. EGb 761 given shortly after initiating mitochondrial damage by sodium nitroprusside (nitric oxide donor) improved the mitochondrial membrane potential of PC12 cells significantly and dose dependently. Under these conditions, EGb 761 also reversed the decrease in ATP production. In addition, similar protection against oxidative damage was found in dissociated brain cells and isolated brain mitochondria after in vitro or in vivo treatment with EGb 761. Moreover, PC12 cells bearing an Alzheimer's disease-related mutation in the amyloid precursor protein, which leads to enhanced beta amyloid production, showed greater benefit from treatment with EGb 761 than did control cells. Taken together, our findings clearly show stabilization and protection of mitochondrial function as a specific and very sensitive property of EGb 761 at therapeutically relevant doses.

Analysis of apoptosome dysregulation in pancreatic cancer and of its role in chemoresistance

The apoptosome is a multiprotein complex mediating the mitochondrial pathway of cell death. Its importance during development has been clearly demonstrated by knocking out key genes in mouse. APAF1 is the core protein of the apoptosome and its dosage is also critical in various cancer types, i.e., melanoma, germ line tumor, gastrointestinal cancer and B-type chronic lymphocytic leukemia. This is generally due to inactivation of the APAF1 locus by epigenetic phenomena or by activity of promoter regulators. We investigated the putative roles of the apoptosome in pancreatic ductal adenocarcinoma (PDAC). We found that both APAF1 mRNA and protein are dysregulated in human PDAC samples. Similarly, several PDAC cell lines exhibited variable levels of both APAF1 protein and mRNA. The response to cell death induction and its biochemical features were assessed by treatment of each line with commonly used chemotherapeutic agents. We found that the apoptosome pathway was not functional in most cell lines upon cytochrome c release from mitochondria. In addition, we restored APAF1 and Caspase-9 dosage in Panc-1 cells, where the apoptosome is downregulated, by overexpressing the murine cDNA of the two molecules, and we improved the death response to chemotherapeutic agents.

Gene transfer of insulin-like growth factor-I providing neuroprotection after spinal cord injury in rats

OBJECT

Insulin-like growth factor-I (IGF-I) has been shown to be a potent neurotrophic factor that promotes the growth of projection neurons, dendritic arborization, and synaptogenesis. Its neuroprotective roles may be coordinated by activation of Akt, inhibition of glycogen synthase kinase-3beta (GSK-3beta), and thus inhibition of tau phosphorylation. The authors investigated the role and mechanism of IGF-I gene transfer after spinal cord injury (SCI).

METHODS

Studies were performed in 40 male Sprague-Dawley rats after spinal cord hemisection. The authors conducted hydrodynamics-based gene transfection in which an IGF-I plasmid was rapidly injected into the rat's tail vein 30 minutes after SCI. The animals were randomly divided into four groups: Group I, sham operated; Group II, SCI treated with pCMV-IGF-I gene; Group III, SCI treated with vehicle pCMV-LacZ gene; and Group IV, SCI only. The results showed that IGF-I gene transfer promoted motor recovery, antiinflammatory responses, and antiapoptotic effects after SCI. Using techniques of Western blotting and immunohistochemistry, the authors assessed the mechanism of IGF-I gene transfer after SCI in terms of activation of Akt, inhibition of GSK-3beta, attenuation of p35, and inhibition of tau phosphorylation. Moreover, they found that IGF-I gene transfer could block caspase-9 cleavage, increase Bcl-2 formation, and thus inhibit apoptosis after SCI.

CONCLUSIONS

The intravenous administration of IGF-I after SCI activated Akt, attenuated GSK-3beta, inhibited p35 activation, diminished tau hyperphosphorylation, ended microglia and astrocyte activation, inhibited neuron loss, and significantly improved neurological dysfunction. Furthermore, IGF-I attenuated caspase-9 cleavage, increased Bcl2, and thus inhibited apoptosis after SCI.

Treatment of MCF-7 cells with taxol and etoposide induces distinct alterations in the expression of apoptosis-related genes BCL2, BCL2L12, BAX, CASPASE-9 and FAS

We studied alterations in the mRNA expression levels of BCL2 (Bcl-2), BCL2L12, BAX, FAS and CASPASE-9 genes in the MCF-7 breast cancer cell line in response to treatment with two anticancer drugs. Cell toxicity was evaluated by the MTT method, trypan blue staining and DNA laddering, whereas the expression levels of the apoptosis-related genes were analysed by RT-PCR using gene-specific primers. In the case of etoposide, down-regulation of the BCL2L12-A gene variant and of CASPASE-9, as well as upregulation of BAX, was observed, whereas treatment of MCF-7 cells with taxol led to down-regulation of the mRNA levels of all genes examined. Our results support the idea that after long-term clinical studies, mRNA expression analysis of BCL2L12 and other members of the BCL2 gene family may serve as useful molecular markers predicting chemotherapy response in breast cancer.

Massive apoptosis erodes nasal mucosa of cocaine abusers

BACKGROUND

A threatening occurrence in some cocaine abusers is the progressive destruction of nasal structures (cocaine-induced midline destructive lesions [CIMDL]) that may end in a highly severe disease.

METHODS

Thirty patients with CIMDL, 10 healthy patients, 10 patients affected by nasal polyposis, and 10 patients affected by Wegener granulomatosis were observed. Biopsy specimens of nasal mucosa were analyzed by immunohistochemistry for caspases-3, -9 and -8 and by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxygenin nick end labeling (TUNEL) method. The time and concentration-dependent effects of cocaine in vitro were studied in HaCat cells by TUNEL and Western blotting.

RESULTS

All CIMDL biopsy specimens showed abundant caspase-3 and caspase-9 expression but no caspase-8 positive cells. No obvious expression of any caspases was detected in biopsy specimens from healthy subjects or in patients affected by nasal polyposis or Wegener granulomatosis. In HaCat cells cellular changes were observed, which confirmed induction of massive apoptotic events. The rate of apoptosis in HaCat cells was dependent on the concentration of cocaine. After 1 hour, 2.5, 5, and 10 mM of cocaine induced 16, 45, and 84% of apoptotic figures, respectively, while 6 hours of exposure increased apoptosis to 25, 54, and 94% at the same concentrations. Caspase expression and activation in HaCat cells treated with 100 microM and 1 mM of cocaine for 1 hour were confirmed by Western blotting.

CONCLUSION

Cultured epithelial cells show both time- and dose-dependent increases in apoptosis and cellular damage on cocaine treatment. We suggest that some abusers trigger CIMDL by abnormally boosting apoptosis within nasal epithelial cells. Cocaine abusers with higher apoptotic rates may predict whether they will eventually develop CIMDL.