Arsenic trioxide induces growth inhibition and death in human pulmonary artery smooth muscle cells accompanied by mitochondrial O2•- increase and GSH depletion.

Arsenic trioxide (ATO; As2 O3 ) induces cell death in various cells via oxidative stress. Expose to chronic arsenic is involved in the development of vascular diseases. However, little is known about the cytotoxic effects of ATO on human normal vascular smooth muscle cells (VSMCs). Thus, in this study, we investigated the effects of ATO on cell growth and death in human pulmonary artery smooth muscle (HPASM) cells in relation to reactive oxygen species (ROS) and glutathione (GSH) levels. ATO treatment decreased the growth of HPASM cells with an IC50 of ∼30-50 µM at 24 h, and ATO induced HPASM cell death via apoptosis or necrosis dependent on the doses of it at this time. Treatment with 50 µM ATO did not increase ROS levels at the early time points, but it significantly increased mitochondrial O2•- levels at 24 h. ATO also induced GSH depletion in HPASM cells. N-acetyl cysteine (NAC; a well-known antioxidant) did not significantly affect apoptotic cell death, ROS levels, or GSH depletion in ATO-treated HPASM cells. However, l-buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) intensified mitochondrial O2•- levels in ATO-treated HPASM cells, and significantly increased cell death and GSH depletion in these cells as well. In summary, we provided the first evidence that ATO inhibited the growth of HPASM cells, and induced apoptotic and/or necrotic cell death in these cells, accompanied by increases in mitochondrial O2•- level and GSH depletion.

The ameliorative effects of L-2-oxothiazolidine-4-carboxylate on acetaminophen-induced hepatotoxicity in mice.

The aim of the study was to investigate the ameliorative effects and the mechanism of action of L-2-oxothiazolidine-4-carboxylate (OTC) on acetaminophen (APAP)-induced hepatotoxicity in mice. Mice were randomly divided into six groups: normal control group, APAP only treated group, APAP + 25 mg/kg OTC, APAP + 50 mg/kg OTC, APAP + 100 mg/kg OTC, and APAP + 100 mg/kg N-acetylcysteine (NAC) as a reference control group. OTC treatment significantly reduced serum alanine aminotransferase and aspartate aminotransferase levels in a dose dependent manner. OTC treatment was markedly increased glutathione (GSH) production and glutathione peroxidase (GSH-px) activity in a dose dependent manner. The contents of malondialdehyde and 4-hydroxynonenal in liver tissues were significantly decreased by administration of OTC and the inhibitory effect of OTC was similar to that of NAC. Moreover, OTC treatment on APAP-induced hepatotoxicity significantly reduced the formation of nitrotyrosin and terminal deoxynucleotidyl transferase dUTP nick end labeling positive areas of liver tissues in a dose dependent manner. Furthermore, the activity of caspase-3 in liver tissues was reduced by administration of OTC in a dose dependent manner. The ameliorative effects of OTC on APAP-induced liver damage in mice was similar to that of NAC. These results suggest that OTC has ameliorative effects on APAP-induced hepatotoxicity in mice through anti-oxidative stress and anti-apoptotic processes.

Gallic acid-induced lung cancer cell death is accompanied by ROS increase and glutathione depletion.

Gallic acid (GA) is generally distributed in a variety of plants and foods, and its various biological effects have been reported. Here, we investigated the effects of GA and/or caspase inhibitors on Calu-6 and A549 lung cancer cells in relation to cell death and reactive oxygen species (ROS). The growths of Calu-6 and A549 cells were diminished with an IC(50) of approximately 30 and 150 µM GA at 24 h, respectively. GA also inhibited the growth of primary human pulmonary fibroblast (HPF) cells with an IC(50) of about 300 µM. GA induced apoptosis and/or necrosis in lung cancer cells, which was accompanied by the loss of mitochondrial membrane potential (MMP, ΔΨ(m)). The percents of MMP (ΔΨ(m)) loss and death cells by GA were lower in A549 cells than in Calu-6 cells. Caspase inhibitors did not significantly rescued lung cancer cells from GA-induced cell death. GA increased ROS levels including O(2) (•-) and induced GSH depletion in both lung cancer cells. Z-VAD (pan-caspase inhibitor) did not decrease ROS levels and GSH depleted cell number in GA-treated lung cancer cells. In conclusion, GA inhibited the growth of lung cancer and normal cells. GA-induced lung cancer cell death was accompanied by ROS increase and GSH depletion.

What is the role of unripe Rubus coreanus extract on penile erection?

The effect of unripe Rubus coreanus extract on rabbit penile corpus cavernosum (PCC) was evaluated. Penises were obtained from healthy male New Zealand white rabbits (2.5-3.0 kg). The pre-contracted penis with phenylephrine (Phe, 10 µM) was treated with various concentrations of an extract of unripe R. coreanus (0.5, 1, 2, 3 and 4 mg/mL). The change in penile tension was recorded, cyclic nucleotides in the perfusate and the PCC were measured by radioimmunoassay, and the expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in the perfused PCC were measured by western blotting. The interaction between unripe R. coreanus and sildenafil was also evaluated. The PCC relaxation induced by the extracts of R. coreanus was in a concentration-dependent manner and enhanced sildenafil-induced PCC relaxation. The perfusion of penile cavernous tissue with the unripe R. coreanus extract increased cGMP and cAMP in the tissue and in the perfusate and the expression of eNOS and nNOS in the tissue. The unripe R. coreanus extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP system and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.

Leptin reduces plasma ANP level via nitric oxide-dependent mechanism.

Leptin is a circulating adipocyte-derived hormone that influences blood pressure (BP) and metabolism. This study was designed to define the possible role of leptin in regulation of the atrial natriuretic peptide (ANP) system using acute and chronic experiments. Intravenous infusion of rat leptin (250 microg/kg injection plus 2 microg.kg(-1).min(-1) for 20 min) into Sprague-Dawley rats increased BP by 25 mmHg and decreased plasma level of ANP from 80.3 +/- 3.45 to 51.8 +/- 3.3 pg/ml. Reserpinization attenuated the rise in BP, but not the reduction of plasma ANP during leptin infusion. N(omega)-nitro-l-arginine methyl ester prevented the effects of leptin on the reduction of ANP level. In hyperleptinemic rats that received adenovirus containing rat leptin cDNA (AdCMV-leptin), BP increased during first 2 days and then recovered to control value. Plasma concentration of ANP and expression of ANP mRNA, but not of atrial ANP, in hyperleptinemic rats were lower than in the control groups on the first and second week after administration of AdCMV-leptin. These effects were not observed by the pretreatment with N(omega)-nitro-l-arginine methyl ester. No differences in renal function and ANP receptor density in the kidney were found between hyperleptinemic and control rats. Basal ANP secretion and isoproterenol-induced suppression of ANP secretion from isolated, perfused atria of hyperleptinemic rats were not different from those of other control groups. These data suggest that leptin inhibits ANP secretion indirectly through nitric oxide without changing basal or isoproterenol-induced ANP secretion.

Myocardial calcification and hypertension following chronic renal failure and ameliorative effects of furosemide and captopril.

OBJECTIVES: The aim of this study was to prevent metastatic myocardial calcification and hypertension following chronic renal failure (CRF). METHODS: A total of 50 male Sprague-Dawley rats were allocated to one of five groups: the control group (sham), the NxNT group (nephrectomized rats receiving no treatment), the NxFuro group (nephrectomized rats treated with furosemide), the NxCap group (nephrectomized rats treated with captopril) and the NxFuroCap group (nephrectomized rats treated with furosemide and captopril). Surgery (5/6 nephrectomy) was performed to induce CRF. Oral treatment with furosemide (20 mg/kg) and/or captopril (0.05 mg/kg) was given twice daily for 5 weeks. Parameters were studied after 5 weeks. RESULTS: In the NxNT group, arterial blood pressure was significantly increased compared with the controls. Monotherapy with furosemide or captopril and both in combination maintained blood pressure to near or below control. Myocardial and remnant-kidney calcification was detected in NxNT rats, but calcification was absent in the NxFuroCap rats. Cardiac hypertrophy and fibrosis was observed in the NxNT group but not in treatment groups. Both plasma inorganic phosphate and Ca(2+) significantly increased in the NxNT group, but the difference was not significant in the treatment groups. CONCLUSION: Furosemide, either alone or in combination with captopril, is capable to prevent myocardial calcification, cardiac hypertrophy and hypertension, maintaining blood Ca(2+) and phosphate levels by slowing CRF.

Reactive oxygen species and glutathione level changes by a proteasome inhibitor, MG132, partially affect calf pulmonary arterial endothelial cell death.

MG132 as a proteasome inhibitor has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). Here, we evaluated the effects of MG132 on the growth of endothelial cells (ECs), especially calf pulmonary artery endothelial cells (CPAECs), in relation to cell death, ROS, and glutathione (GSH) levels. MG132 dose dependently inhibited the growth of CPAEC and human umbilical vein endothelial cells (HUVECs) at 24 hours. MG132 also induced apoptotic cell death in CPAEC, which were accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)). MG132 increased ROS levels, including O(2)(*-) in CPAEC, but not in HUVEC. MG132 also dose dependently increased GSH-depleted cells in both ECs. N-acetyl-cysteine (NAC; a well-known antioxidant) reduced ROS levels in MG132-treated CPAEC with the slight prevention of cell death and GSH depletion. Buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) increased ROS levels and decreased GSH levels in MG132-treated CPAEC without the enhancement of cell death. In conclusion, MG132 inhibited the growth of ECs, especially CPAEC. The changes of ROS and GSH levels by MG132 partially affect CPAEC death.

Treatment with p38 inhibitor intensifies the death of MG132-treated As4.1 juxtaglomerular cells via the enhancement of GSH depletion.

MG132, as a proteasome inhibitor, has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). In this study, we investigated the effects of MG132 and/or MAPK inhibitors on As4.1 juxtaglomerular cells in relation to cell growth, cell death, ROS, and glutathione (GSH) levels. MG132 inhibited the growth of As4.1 cells and induced cell death, accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)) and activation of caspase-3 and -8. MG132 increased ROS levels, and GSH depleted cell numbers. The MEK inhibitor slightly reduced cell growth and caspase-3 activity in MG132-treated As4.1 cells and mildly increased MMP (DeltaPsi(m)) loss and O(2)(*-) level. However, it did not increase apoptosis and GSH depletion. The JNK inhibitor did not strongly influence cell growth, cell death, and GSH depletion by MG132, but increased caspase-3 activity, MMP (DeltaPsi(m)) loss, and O(2)(*-) level. Treatment with the p38 inhibitor magnified cell-growth inhibition and apoptosis by MG132. This agent also strongly increased caspase-8 activity, MMP (DeltaPsi(m)) loss, O(2)(*-) level, and GSH depletion. Conclusively, the p38 inhibitor strongly intensified cell death in MG132-treated As4.1 cells. The changes of GSH content by MG132 and/or MAPK inhibitors were closely related to the death of As4.1 cells.

Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) as an O2(*-) generator induces apoptosis via the depletion of intracellular GSH contents in Calu-6 cells.

Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) is an uncoupler of mitochondrial oxidative phosphorylation in eukaryotic cells. Here, we investigated an involvement of O(2)(*-) and GSH in FCCP-induced Calu-6 cell death and examined whether ROS scavengers rescue cells from FCCP-induced cell death. Levels of intracellular O(2)(*-) were markedly increased depending on the concentrations (5-100 microM) of FCCP. A depletion of intracellular GSH content was also observed after exposing cells to FCCP. Stable SOD mimetics, Tempol and Tiron did not change the levels of intracellular O(2)(*-), apoptosis and the loss of mitochondrial membrane potential (DeltaPsi(m)). Treatment with thiol antioxidants, NAC and DTT, showed the recovery of GSH depletion and the reduction of O(2)(*-) levels in FCCP-treated cells, which were accompanied by the inhibition of apoptosis. In contrast, BSO, a well-known inhibitor of GSH synthesis, aggravated GSH depletion, oxidative stress of O(2)(*-) and cell death in FCCP-treated cells. Taken together, our data suggested that FCCP as an O(2)(*-) generator, induces apoptosis via the depletion of intracellular GSH contents in Calu-6 cells.

The antioxidant, taurine reduced lipopolysaccharide (LPS)-induced generation of ROS, and activation of MAPKs and Bax in cultured pneumocytes.

Lipopolysaccharide (LPS) can cause damage to the epithelia of the respiratory tract. However, taurine can protect the lung tissue from such oxidant-induced inflammation. This study examined the effects of a LPS treatment on the intracellular calcium levels ([Ca(2+)]i) as well as the specific mechanisms of LPS-induced cell death in pneumocytes. In addition, the effects of taurine on the LPS-induced increase in the accumulation of reactive oxygen species (ROS) in pneumocytes were investigated. The [Ca(2+)]i in cultured pneumocytes was determined using microfluorescence techniques. The level of activation of the mitogen-activated protein kinases (MAPKs) and Bax protein were measured by Western blotting. LPS at 10 and 100 ng/ml induced cell death and decreased the viability of MRC-5 cells. Moreover, the intracellular Ca(2+) and ROS levels were increased by LPS. The LPS treatment led to the phosphorylation of ERK1/2, JNK and the activation of Bax. A pretreatment with 20 mM taurine reduced the LPS-induced production of ROS and MARK activity. These results show that a LPS treatment induces cell death in MRC-5 cells by increasing the intracellular ROS and Ca(2+) levels. The increase in the intracellular level of ROS promotes MAPKs activation and Bax translocation. Overall, LPS induces lung cell death by activating MAPKs. Furthermore, taurine decreased the LPS-induced generation of ROS and activation of MAPK and Bax.

Expression of MUC1, MUC2, MUC5AC and MUC6 in cholangiocarcinoma: prognostic impact.

Mucin is a high molecular weight glycoprotein that plays an important role to protect the gastrointestinal tract epithelium. However, in cancer cells and during cancer progression, the expression profile of mucins is altered and expression of some mucins is correlated with prognosis for certain malignancies. The aim of this study was to determine the relationship between the expression of MUC1, MUC2, MUC5AC and MUC6 in cholangiocarcinoma and clinicopathological parameters as well as patient survival. In addition, this study was performed to identify whether immunohistochemical staining for mucins is useful to differentiate cholangiocarcinoma from adenocarcinoma of the pancreas and gallbladder. Immunohistochemical staining for MUC1, MUC2, MUC5AC and MUC6 was performed for 85 cases of cholangiocarcinoma, including 34 cases of intrahepatic cholangiocarcinoma (ICC), 51 cases of extrahepatic cholangiocarcinoma (ECC), 11 cases of gallbladder adenocarcinoma and 14 cases of pancreas adenocarcinoma. For cholangiocarcinomas, positivity of immunohistochemical staining for MUC1, MUC2, MUC5AC and MUC6 was 65.8, 23.5, 61.1 and 14.1%, respectively. For cholangiocarcinomas, MUC1 positivity was determined to be statistically significant for poor differentiation (p=0.002), T category (p=0.003), gross type (ICC, p=0.005; ECC, p=0.006) and poor patient survival (p=0.015). MUC5AC was more frequently expressed in advanced tumors (p=0.013). MUC6 expression was significantly detected in well-differentiated cholangiocarcinomas (p=0.006). There was no significant difference for the mucin staining patterns of cholangiocarcinomas, pancreatic adenocarcinomas and gallbladder adenocarcinomas. These results indicate that MUC1 expression in cholangiocarcinomas is closely related to dedifferentiation, infiltrative growth pattern and patient survival. Our results suggest that the expression of MUC1 might be associated with the progression of cholangiocarcinoma.

The effects of buthionine sulfoximine, diethyldithiocarbamate or 3-amino-1,2,4-triazole on propyl gallate-treated HeLa cells in relation to cell growth, reactive oxygen species and glutathione.

Propyl gallate (PG) as a synthetic antioxidant is widely used in processed food and medicinal preparations. It also exerts a variety of effects on tissue and cell functions. In the present study, we investigated the effects of L-buthionine sulfoximine (BSO, an inhibitor of GSH synthesis), diethyldithiocarbamate (DDC, an inhibitor of Cu/Zn-SOD) or 3-amino-1,2,4-triazole (AT, an inhibitor of catalase) on PG-treated HeLa cells in relation to cell growth, reactive oxygen species (ROS) and glutathione (GSH). Treatment with PG induced growth inhibition, the loss of mitochondrial membrane potential [MMP (DeltaPsim)] and apoptosis in HeLa cells. ROS levels including O2.- were increased or decreased in PG-treated HeLa cells depending on the incubation times. PG caused depletion in GSH content in HeLa cells. While BSO enhanced the growth inhibition of PG-treated HeLa cells at 4 h, DDC and AT did not. All the agents down-regulated MMP (DeltaPsim) levels in PG-treated cells. Although BSO, DDC or AT slightly increased ROS or O2.- levels in PG-treated cells at 1 h, these enhancements of ROS did not intensify apoptosis in these cells. In addition, BSO, DDC or AT slightly reduced GSH level in PG-treated HeLa cells at 1 h, but this reduction did not affect cell death of HeLa. Furthermore, PG induced a G1 phase arrest of the cell cycle. BSO, DDC or AT significantly inhibited the G1 phase arrest in PG-treated cells. Conclusively, the changes of ROS and GSH levels by BSO, DDC or AT in PG-treated HeLa cells did not strongly affect the cell growth and death.

Pyrogallol inhibits the growth of human pulmonary adenocarcinoma A549 cells by arresting cell cycle and triggering apoptosis.

Pyrogallol (PG) is a polyphenol compound and has been known to be an O(2)(*-) generator. We evaluated the effects of PG on the growth of human pulmonary A549 cells in relation to the cell cycle and apoptosis. Treatment with 50 or 100 microM PG significantly inhibited the cell growth of A549 for 72 h. DNA flow cytometric analysis indicated that PG slightly induced a G1 phase arrest of the cell cycle at 24 or 48 h, but did not induce the specific cell cycle arrest at 72 h. Intracellular GSH depletion was observed in PG-treated cells. PG induced apoptosis in A549 cells, as evidenced by sub-G1 cells, annexin V staining cells, and the loss of mitochondrial membrane potential (DeltaPsi(m)). The intracellular ROS (reactive oxygen species) level including O(2)(*-) increased in PG-treated A549 cells at 24 and 48 h, and persisted at 72 h. The changes in GSH as well as ROS levels by PG affected the cell viability in A549 cells. In conclusion, PG inhibited the growth of human pulmonary A549 cells by inducing cell cycle arrest as well as triggering apoptosis.

Intracellular GSH level is a factor in As4.1 juxtaglomerular cell death by arsenic trioxide.

Arsenic trioxide has been known to regulate many biological functions such as cell proliferation, apoptosis, differentiation, and angiogenesis in various cell lines. We investigated the involvement of GSH and ROS such as H(2)O(2) and O(2)(*-) in the death of As4.1 cells by arsenic trioxide. The intracellular ROS levels were changed depending on the concentration and length of incubation with arsenic trioxide. The intracellular O(2)(*-) level was significantly increased at all the concentrations tested. Arsenic trioxide reduced the intracellular GSH content. Treatment of Tiron, ROS scavenger decreased the levels of ROS in 10 microM arsenic trioxide-treated cells. Another ROS scavenger, Tempol did not decrease ROS levels in arsenic trioxide-treated cells, but slightly recovered the depleted GSH content and reduced the level of apoptosis in these cells. Exogenous SOD and catalase did not reduce the level of ROS, but did decrease the level of O(2)(*-). Both of them inhibited GSH depletion and apoptosis in arsenic trioxide-treated cells. In addition, ROS scavengers, SOD and catalase did not alter the accumulation of cells in the S phase induced by arsenic trioxide. Furthermore, JNK inhibitor rescued some cells from arsenic trioxide-induced apoptosis, and this inhibitor decreased the levels of O(2)(*-) and reduced the GSH depletion in these cells. In summary, we have demonstrated that arsenic trioxide potently generates ROS, especially O(2)(*-), in As4.1 juxtaglomerular cells, and Tempol, SOD, catalase, and JNK inhibitor partially rescued cells from arsenic trioxide-induced apoptosis through the up-regulation of intracellular GSH levels.

Apoptosis in arsenic trioxide-treated Calu-6 lung cells is correlated with the depletion of GSH levels rather than the changes of ROS levels.

Arsenic trioxide (ATO) can regulate many biological functions such as apoptosis and differentiation in various cells. We investigated an involvement of ROS such as H(2)O(2) and O(2)(*-), and GSH in ATO-treated Calu-6 cell death. The levels of intracellular H(2)O(2) were decreased in ATO-treated Calu-6 cells at 72 h. However, the levels of O(2)(*-) were significantly increased. ATO reduced the intracellular GSH content. Many of the cells having depleted GSH contents were dead, as evidenced by the propidium iodine staining. The activity of CuZn-SOD was strongly down-regulated by ATO at 72 h while the activity of Mn-SOD was weakly up-regulated. The activity of catalase was decreased by ATO. ROS scavengers, Tiron and Trimetazidine did not reduce levels of apoptosis and intracellular O(2)(*-) in ATO-treated Calu-6 cells. Tempol showing a decrease in intracellular O(2)(*-) levels reduced the loss of mitochondrial transmembrane potential (DeltaPsi(m)). Treatment with NAC showing the recovery of GSH depletion and the decreased effect on O(2)(*-) levels in ATO-treated cells significantly inhibited apoptosis. In addition, BSO significantly increased the depletion of GSH content and apoptosis in ATO-treated cells. Treatment with SOD and catalase significantly reduced the levels of O(2)(*-) levels in ATO-treated cells, but did not inhibit apoptosis along with non-effect on the recovery of GSH depletion. Taken together, our results suggest that ATO induces apoptosis in Calu-6 cells via the depletion of the intracellular GSH contents rather than the changes of ROS levels.

A superoxide anion generator, pyrogallol, inhibits the growth of HeLa cells via cell cycle arrest and apoptosis.

We investigated the in vitro effects of pyrogallol on cell growth, cell cycle regulation, and apoptosis in HeLa cells. Pyrogallol inhibited the growth of HeLa cells with an IC(50) of approximately 45 microM. Pyrogallol induced arrest during all phases of the cell cycle and also very efficiently resulted in apoptosis in HeLa cells, as evidenced by flow cytometric detection of sub-G1 DNA content, annexin V binding assay, and DAPI staining. This apoptotic process was accompanied by the loss of mitochondrial transmembrane potential (DeltaPsi(m)), Bcl-2 decrease, caspase-3 activation, and PARP cleavage. Pan-caspase inhibitor (Z-VAD) could rescue some HeLa cells from pyrogallol-induced cell death, while caspase-8 and -9 inhibitors unexpectedly enhanced the apoptosis. When we examined the changes of the ROS, H(2)O(2) or O(2)(*-) in pyrogallol-treated cells, H(2)O(2) was slightly increased and O(2)(*-) significantly was increased. In addition, we detected a decreased GSH content in pyrogallol-treated cells. Only pan-caspase inhibitor showing recovery of GSH depletion and reduced intracellular O(2)(*-) level decreased PI staining in pyrogallol-treated HeLa cells, which indicates dead cells. In summary, we have demonstrated that pyrogallol as a generator of ROS, especially O(2) (*-), potently inhibited the growth of HeLa cells through arrests during all phases of the cell cycle and apoptosis.

Enhancement of arsenic trioxide-induced apoptosis in HeLa cells by diethyldithiocarbamate or buthionine sulfoximine.

Arsenic trioxide (ATO) affects many biological functions such as cell proliferation, apoptosis, differentiation and angiogenesis in various cells. We investigated the in vitro effects of ATO as a reactive oxygen species (ROS) generator or a glutathione (GSH) depletor on apoptosis in HeLa cells. ATO decreased the viability of HeLa cells in a dose-dependent manner with an IC50 of approximately 5-6 microM. ATO triggered apoptosis, which is accompanied by the loss of mitochondrial transmembrane potential (DeltaPsim). Intracellular general ROS levels in HeLa cells were increased or decreased depending on the concentration of ATO. Particularly, the levels of O2.- were increased by ATO. In addition, we detected a decreased GSH content in ATO-treated cells. The GSH-depleted cells mainly showed propidium iodine-positive staining, indicating that the majority of the cells were dead. Diethyldithiocarbamate (DDC; an inhibitor of Cu,Zn-SOD) induced apoptosis and the loss of mitochondrial transmembrane potential (DeltaPsim) in HeLa control cells. DDC intensified apoptosis, the loss of mitochondrial transmembrane potential, increased levels of O2.- and GSH depletion in ATO-treated cells. L-buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) did not induce apoptosis in HeLa control cells, but increased levels of apoptosis, O2.- and GSH depletion in ATO-treated cells. In conclusion, the changes in intracellular GSH levels rather than ROS levels are tightly related to the enhancement of ATO-induced apoptosis in HeLa cells by DDC or BSO.

Caspase inhibitor decreases apoptosis in pyrogallol-treated lung cancer Calu-6 cells via the prevention of GSH depletion.

Pyrogallol (PG) is a polyphenol compound and is known to be an O2.- generator. In the present study, we evaluated the anti-apoptotic effects of caspase inhibitors in relation to changes in reactive oxygen species (ROS) and glutathione (GSH) levels in PG-treated human pulmonary adenocarcinoma Calu-6 cells. Treatment with 50 microM PG inhibited the growth of Calu-6 cells approximately 60% and induced apoptosis approximately 17% at 24 h, accompanied by mitochondrial membrane potential loss (DeltaPsim). Treatment with pan-caspase inhibitor (Z-VAD-FMK), caspase-3 inhibitor (Z-DEVD-FMK), caspase-8 inhibitor (Z-IETD-FMK) and caspase-9 inhibitor (Z-LEHD-FMK) significantly prevented apoptosis in PG-treated Calu-6 cells at 24 h. PG increased the ROS and depleted GSH contents in Calu-6 cells. Treatment with each caspase inhibitor did not significantly change the ROS and GSH levels in PG-treated Calu-6 cells at 24 h. However, Z-VAD significantly prevented GSH depletion in PG-treated Calu-6 cells at the late time phase of 72 h. Conclusively, the anti-apoptotic effect of caspase inhibitor on PG-induced Calu-6 cell death was closely related to changes in GSH content rather than ROS levels.

Apoptosis in pyrogallol-treated Calu-6 cells is correlated with the changes of intracellular GSH levels rather than ROS levels.

We investigated the involvement of glutathione (GSH) and reactive oxygen species (ROS) such as H2O2 and O2-* in the deaths of pyrogallol-treated Calu-6 cells. Pyrogallol inhibited the growth of Calu-6 cells with an IC50 of approximately 50 microM. Levels of intracellular H2O2 were not altered or were decreased in pyrogallol-treated Calu-6 cells at 72 h. However, levels of O2*- were increased. Treatment with pyrogallol also reduced the intracellular GSH content. The activity of SOD was down-regulated, but the activity of catalase was up-regulated by pyrogallol at 72 h. ROS scavengers, including Tempol, Tiron, Trimetazidine, and N-acetylcysteine (NAC), did not reduce the levels of the intracellular O2*-. Tempol showing the recovery of GSH depletion in pyrogallol-treated cells significantly prevented apoptosis, while Tiron prevented the loss of mitochondrial transmembrane potential (DeltaPsi(m)). In contrast, treatment with NAC showing an increased effect on O2*- levels and depletion of GSH intensified pyrogallol-induced apoptosis. In addition, treatment with SOD and catalase significantly prevented the loss of mitochondrial transmembrane potential (DeltaPsi(m)) in pyrogallol-treated Calu-6 cells. However, only catalase showing a decreased effect on O2*- levels and depletion of GSH prevented pyrogallol-induced apoptosis. Taken together, apoptosis in pyrogallol-treated Calu-6 cells is correlated with the changes of intracellular GSH levels rather than ROS levels.

Attenuation of hypoosmotic stress-induced ANP secretion via I(Cl,swell) in renal hypertensive rat atria.

Cardiac hypertrophy, an adaptive process to an increased hemodynamic overload, includes not only an increase in cell size but also qualitative changes in constituent proteins. Although swelling-activated chloride channels (I(Cl,swell)) chronically activate in hypertrophied atrial myocytes, the role of I(Cl,swell) in regulation of atrial natriuretic peptide (ANP) release is poorly understood. We investigated the effects of I(Cl,swell) on ANP release and contractility and its modification in hypertrophied rat atria. To stimulate I(Cl,swell), hypoosmotic HEPES buffered solution (0.8T, 0.7T and 0.6T) was perfused into isolated perfused beating atria. The hypoosmotic HEPES buffered solution increased ANP release as compared to isoosmotic buffered solution (1T) in an osmolarity-reduction dependent manner. Atrial contractility and extracellular fluid translocation did not change. Exposure to hypoosmotic buffer (0.8T) containing low chloride (8mM), tamoxifen or diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) significantly attenuated hypoosmolarity-induced ANP release. The pretreatment with genistein, okdaic acid, U73122, GF109203x, and staurosporine attenuated hypoosmolarity-induced ANP release whereas orthovanadate augmented it significantly. In hypertrophied atria from renal hypertensive rats, hypoosmolarity-induced ANP release was markedly attenuated and DIDS-induced decrease in ANP release and negative inotropy were augmented as compared to sham-operated rat atria. Therefore, we suggest that I(Cl,swell) may partly participate hypoosmolarity-induced ANP release through protein tyrosine kinase and phospholipase C-protein kinase C pathway. The modification of responses of ANP release to hypoosmolarity and DIDS in hypertrophied atria may relate to changes in I(Cl,swell) activity by persistent high blood pressure.