Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms of adrenal damage induced by 7,12-dimethylbenz (alpha) anthrancene (DMBA) in 50-day-old female Sprague--Dawley rats were investigated. A single dose of DMBA, either fed (30 mg) per os or injected (6 mg) in a caudal vein, caused inner cortical cell death (cells of the zonae fasciculata and reticularis) by an apoptotic mechanism. Apoptotic cells were identified by cell morphology, and terminal dUTP nick end labeling (TUNEL)-positive cells were seen at 12 hrs post-DMBA, reached a maximum at 36 h, and were accompanied by blood congestion followed by massive hemorrhage leading to post-apoptotic necrosis at 48 and 72 h. The apoptotic cascade involved the up-regulation of Bax, the down-regulation of Bcl-2, and the activation of caspase-3. At 72 h, regeneration as evidenced by the appearance of 5-bromo-2'-deoxyuridine-positive cells began to occur in the damaged inner cortical zones, with the cells proliferating toward the medulla thereafter. Regenerative cells expressed cytochrome P450 11 beta hydroxylase. The damage was repaired but calcification appeared at 2 weeks post-DMBA, leaving bow-shaped lesions in some adrenals.
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PMID:Mechanisms of adrenal damage induced by 7,12-dimethylbenz (alpha) anthrancene in female Sprague--Dawley rats. 1126 59

The anti-HIV drug 3'-azido-3'-deoxythymidine (AZT) is the drug of choice for preventing maternal-fetal HIV transmission during pregnancy. Our aim was to assess the cytotoxic effects of AZT on human placenta in vitro. The mechanisms of AZT-induced effects were investigated using JEG-3 choriocarcinoma cells and primary explant cultures from term and first-trimester human placentas. Cytotoxicity measures included trypan blue exclusion, MTT, and reactive oxygen species (ROS) assays. Apoptosis was measured with an antibody specific to cleaved caspase-3 and by rescue of cells by the general caspase inhibitor Boc-D-FMK. The effect of AZT on the activities of glutathione-S-transferase, beta-glucuronidase, UDP-glucuronosyl transferase, cytochrome P450 (CYP) 1A, and CYP reductase (CYPR) in the placenta was assessed using biochemical assays and immunoblotting. AZT increased ROS levels, decreased cellular proliferation rates, was toxic to mitochondria, and initiated cell death by a caspase-dependent mechanism in the human placenta in vitro. In the absence of serum, the effects of AZT were amplified in all the models used. AZT also increased the amounts of activity of GST, beta-glucuronidase, and CYP1A, whereas UGT and CYPR were decreased. We conclude that AZT causes apoptosis in the placenta and alters metabolizing enzymes in human placental cells. These findings have implications for the safe administration of AZT in pregnancy with respect to the maintenance of integrity of the maternal-fetal barrier.
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PMID:3'-azido-3'-deoxythymidine (AZT) induces apoptosis and alters metabolic enzyme activity in human placenta. 1455 Jul 50

Transforming growth factor-beta (TGF-beta) induces an oxidative stress process in hepatocytes that mediates its apoptotic activity. To determine the cellular source of the early reactive oxygen species (ROS) generated by fetal rat hepatocytes in response to TGF-beta, we used inhibitors that block different ROS-producing systems. Diphenyleneiodonium, which inhibits NADPH oxidase and other flavoproteins, completely blocked the increase in ROS induced by TGF-beta, coincidently with an impairment of caspase-3 activation and cell death. Rotenone, an inhibitor of the NADH dehydrogenase in mitochondrial complex I, attenuated, but did not completely inhibit, ROS-production, caspase activation, and cell death mediated by TGF-beta. No significant protection was observed with inhibitors of other ROS-producing systems, such as cytochrome P450 (metyrapone), cyclooxygenase (indomethacin), and xanthine oxidase (allopurinol). Additional experiments have indicated that two different mechanisms could be involved in the early ROS production by TGF-beta. First, an inducible (cycloheximide-inhibited) NADPH oxidase-like system could account for the extramitochondrial production of ROS. Second, TGF-beta could increase ROS by a rapid downregulation of antioxidant genes. In particular, intramitochondrial ROS would increase by depletion of MnSOD. Finally, glutathione depletion is a late event and it would be more the consequence than the cause of the increase in ROS induced by TGF-beta.
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PMID:Source of early reactive oxygen species in the apoptosis induced by transforming growth factor-beta in fetal rat hepatocytes. 1473 87

3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) is one of the dietary carcinogens. At the initial step in the carcinogenic process, its exocyclic amino group is metabolically activated to the hydroxyamino derivative by the cytochrome P450 (CYP) 1A and 1B subfamily and then form DNA adducts, which are considered to be the main cause of DNA damage during the carcinogenic process. On the other hand, our previous study has shown that Trp-P-1 exhibits cytotoxicity to primary cultured rat hepatocytes, via induction of caspase-9-dependent apoptosis without being metabolized by CYP 1A1. In the present study, we investigated what type of DNA damage would be involved in the induction of apoptosis induced by Trp-P-1. When RL-34 cells derived from normal rat liver were treated with a high (30 microM) concentration of Trp-P-1, apoptotic events such as the loss of cell viability, nuclear condensation and the activation of caspase-3 were observed. In these apoptotic cells, intracellular topoisomerase I activity was inhibited and histone H2AX phosphorylation, which occurs after introduction of DNA double-strand breaks (DSBs), was observed in the early phase of the apoptosis. On the other hand, treatment with a non-apoptotic concentration (1 microM) of Trp-P-1 increased the formation of 8-hydroxy-2'-deoxyguanosine. The formation of DNA adducts was detected at almost the same level in both cells exposed to the apoptotic and non-apoptotic concentrations of Trp-P-1. These results indicate that Trp-P-1-induced apoptosis was triggered by DNA DSBs through the inhibition of topoisomerase I but not the formation of DNA adducts.
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PMID:3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) triggers apoptosis by DNA double-strand breaks caused by inhibition of topoisomerase I. 1497 28

We previously showed that HIV-1 protease inhibitors (PIs) slowed the proliferation of human myeloid leukemia cells and enhanced their differentiation in the presence of all-trans-retinoic acid. In this study, we found that PIs, including ritonavir, saquinavir, and indinavir, inhibited the growth of DU145 and PC-3 androgen-independent prostate cancer cells as measured by a clonal proliferation assay. Recent studies showed that ritonavir inhibited cytochrome P450 3A4 enzyme (CYP3A4) in liver microsomes. The CYP3A4 is involved in drug metabolism and acquisition of drug resistance. To clarify the drug interaction between ritonavir and other anticancer drugs, we cultured DU145 cells with docetaxel either alone or in combination with ritonavir. Ritonavir enhanced the antiproliferative and proapoptotic effects of docetaxel in the hormonally independent DU145 prostate cancer cells in vitro as measured by the clonogenic soft agar assay and detection of the activated form of caspase-3 and cleavage of poly(ADP-ribose) polymerase using Western blot analysis. Real-time PCR showed that docetaxel induced the expression of CYP3A4 at the transcriptional level, and ritonavir (10(-5) mol/L) completely blocked this induction. An ELISA-based assay also showed that ritonavir inhibited DNA binding activity of nuclear factor kappaB (NFkappaB) in DU145 cells, which is a contributor to drug resistance in cancer cells. Furthermore, combination treatment of docetaxel and ritonavir dramatically inhibited the growth of DU145 cells present as tumor xenografts in BNX nude mice compared with either drug alone. Importantly, docetaxel induced expression of CYP3A4 in DU145 xenografts, and ritonavir completely blocked this induction. Ritonavir also inhibited NFkappaB DNA binding activity in DU145 xenografts. Extensive histologic analyses of the liver, spleen, kidneys, bone marrow, skin, and subcutaneous fat pads from these mice showed no abnormalities. In summary, combination therapy of ritonavir and anticancer drugs holds promise for the treatment of individuals with advanced, drug resistant cancers.
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PMID:HIV-1 protease inhibitor, ritonavir: a potent inhibitor of CYP3A4, enhanced the anticancer effects of docetaxel in androgen-independent prostate cancer cells in vitro and in vivo. 1549 66

We previously showed that inhibition of catalase and glutathione peroxidase activities in rat primary hepatocytes by 3-amino-1,2,4-triazole (ATZ) and mercaptosuccinic acid (MS) results in endogenous oxidative stress and apoptosis. For the present study, we determined whether this apoptosis involved activation of caspase-3, which is known to execute apoptosis in many cell types. ATZ and MS increased levels of reactive oxygen species (ROS) from 3-9 h, just before the onset of chromatin condensation (apoptosis) and decreases in protein thiols. Pretreatment with either SKF, a cytochrome P450 inhibitor, or L-ascorbic acid, an antioxidant, completely suppressed the increase in ROS levels and apoptosis, suggesting that the sustained ROS increases may cause the apoptosis. SKF also abolished the decrease in protein thiol content, further supporting the contribution of the P450 system to increased ROS levels. DEVD-CHO, a caspase-3 inhibitor, even at 1 mM had no effect on apoptosis. Caspase-3 activity remained unchanged and pro-caspase-3 processing was not detected during 18 h incubation with ATZ and MS. Moreover, the amount of unoxidized pro-caspase-3 decreased even below the level of untreated hepatocytes. These findings suggest that the sustained oxidative stress is a major cause for the hepatocyte apoptosis, which occurs independently of the caspase-3 related pathway.
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PMID:Primary hepatocyte apoptosis is unlikely to relate to caspase-3 activity under sustained endogenous oxidative stress. 1576 64

Aflatoxin B1 (AFB1) is a potent dietary hepatocarcinogen in animals and probably in humans. Mutations (and altered expression) of the tumor suppresser gene p53 have been observed in liver tumors from patients exposed to high dietary AFB1. Inhalation of AFB1-laden grain dusts has been associated with an increased incidence of lung cancer in humans as well. We examined the effects of low concentrations of AFB1 on the expression of p53 and MDM2 in human bronchial epithelial cells (BEAS-2B) transfected with cDNA for either cytochrome P450 (CYP) 1A2 (B-CMV1A2) or CYP 3A4 (B3A4), two isozymes that are responsible for AFB1 activation in human liver and possibly the lung. Untreated B-CMV1A2 and B3A4 cells constitutively expressed p53. Exposure to a range (0.015-15 microM for 30 min) of AFB1 concentrations caused a concentration-dependent decline in p53 expression in B-CMV1A2 cells, and to a lesser extent, in B3A4 cells. The AFB1-mediated decrease in p53 continued for at least 12 h after 30-min exposures to 1.5 muM AFB(1). Mirroring the decrease in p53 expression was a concentration-dependent increase in the expression of the 76-kDa MDM2 isoform in B-CMV1A2 and B-3A4 cells. Interestingly, AFB1 did not induce DNA laddering, an indicator of apoptotic cell death, but proteolytic activation of caspase-3 was detected in AFB1-treated B-CVM1A2 cells. In total, these data show that low, environmentally-relevant concentrations of AFB1 alter the expression of p53 and MDM2 in these human lung cells, and that cells that stably express CYP 1A2 were more susceptible to this effect than nontransfected, or 3A4-expressing cells.
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PMID:Aflatoxin B1 alters the expression of p53 in cytochrome P450-expressing human lung cells. 1628 Mar 84

Chronic alcohol abuse, a major health problem, causes liver and pancreatic diseases and is known to impair hepatic alcohol dehydrogenase (ADH). Hepatic ADH-catalyzed oxidation of ethanol is a major pathway for the ethanol disposition in the body. Hepatic microsomal cytochrome P450 (CYP2E1), induced in chronic alcohol abuse, is also reported to oxidize ethanol. However, impaired hepatic ADH activity in a rat model is known to facilitate a nonoxidative metabolism resulting in formation of nonoxidative metabolites of ethanol such as fatty acid ethyl esters (FAEEs) via a nonoxidative pathway catalyzed by FAEE synthase. Therefore, the metabolic basis of ethanol-induced cytotoxicity was determined in HepG2 cells and recombinant HepG2 cells transfected with ADH (VA-13), CYP2E1 (E47) or ADH + CYP2E1 (VL-17A). Western blot analysis shows ADH deficiency in HepG2 and E47 cells, compared to ADH-overexpressed VA-13 and VL-17A cells. Attached HepG2 cells and the recombinant cells were incubated with ethanol, and nonoxidative metabolism of ethanol was determined by measuring the formation of FAEEs. Significantly higher levels of FAEEs were synthesized in HepG2 and E47 cells than in VA-13 and VL-17A cells at all concentrations of ethanol (100-800 mg%) incubated for 6 h (optimal time for the synthesis of FAEEs) in cell culture. These results suggest that ADH-catalyzed oxidative metabolism of ethanol is the major mechanism of its disposition, regardless of CYP2E1 overexpression. On the other hand, diminished ADH activity facilitates nonoxidative metabolism of ethanol to FAEEs as found in E47 cells, regardless of CYP2E1 overexpression. Therefore, CYP2E1-mediated oxidation of ethanol could be a minor mechanism of ethanol disposition. Further studies conducted only in HepG2 and VA-13 cells showed lower ethanol disposition and ATP concentration and higher accumulation of neutral lipids and cytotoxicity (apoptosis) in HepG2 cells than in VA-13 cells. The apoptosis observed in HepG2 vs. VA-13 cells incubated with ethanol appears to be mediated by release of mitochondrial cytochrome c via activation of caspase-9 and caspase-3. These results strongly support our hypothesis that diminished hepatic ADH activity facilitates nonoxidative metabolism of ethanol and the products of ethanol nonoxidative metabolism cause apoptosis in HepG2 cells via intrinsic pathway.
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PMID:Metabolic basis of ethanol-induced cytotoxicity in recombinant HepG2 cells: role of nonoxidative metabolism. 1680 43

Polychlorinated biphenyl (PCBs) levels of tens and hundreds of pg/ml for individual congeners are measured in human follicular fluid. PCB3 (4-chlorobiphenyl), caused a significant increase in estradiol secretion in porcine granulose-theca cell co-cultures and its two metabolites, 4-OH-PCB3 and 3,4-diOH-PCB3, were even more potent than PCB3 itself [Ptak, A., Ludewig, G., Lehmler, H.J., Wojtowicz, A.K., Robertson, L.W., Gregoraszczuk, E.L. 2005. Comparison of the actions of 4-chlorobiphenyl and its hydroxylated metabolites on estradiol secretion by ovarian follicles in primary cells in culture. Reprod. Toxicol. 20, 57-64]. The question is whether these follicle cells are potentially able to metabolize PCB3 to hydroxylated and genotoxic or cytotoxic intermediates. We report here that granulose-theca co-cultures express xenobiotic-metabolizing cytochrome P450 activities, with CYP1A1>CYP2B>>CYP1A2. A significant increase in CYP1A1 and 2B, but not CYP1A2, activity was seen in cells that were exposed to 6 ng/ml PCB3 or 20 nM 17-beta-estradiol. An increase in caspase-3 activity, indicative for apoptosis, was only observed in PCB3-exposed cells after 24 h exposure. Genotoxicity, determined with the Comet assay, was initially reduced after 24 h exposure to PCB3 and both metabolites compared to untreated controls, followed by a significant transient increase in Comets at the 4 and 24 h time point with PCB3 and 4-OH-PCB3. 3,4-diOH-PCB3 induced a significant increase only after 72 h of recovery. We hypothesize that these biphasic damage kinetics may be due to cross-links caused by adduct formation. These results show for the first time that granulose-theca cells in co-culture express CYP1A1, 2B and 1A2 activities and that PCBs at concentrations that are reached in the environment induce genotoxicity in granulosa cells.
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PMID:Induction of cytochromes P450, caspase-3 and DNA damage by PCB3 and its hydroxylated metabolites in porcine ovary. 1694 19

Atresia and luteolysis are well-documented processes in which most of the growing ovarian follicles and all corpora lutea, respectively, are eliminated by apoptosis. We have previously reported that LH and FSH enhance caspase-3 and -7 activity and apoptosis in the theca-interstitial cells of rat preovulatory follicles in culture. Here we have used cultured follicles to examine whether LH-induced caspase activation is related to the ability of LH to stimulate steroid production. In these studies, we used three inhibitors of enzymes involved in steroid production: aminoglutethimide and ketoconazole, acting on cytochrome P450 side-chain cleavage (P450scc) located at the mitochondria, and epostane, acting on 3beta-hydroxysteroid dehydrogenase located at the endoplasmic reticulum. We found that treatment with either aminoglutethimide or ketoconazole, but not with epostane, significantly reduced LH-induced caspase-3 and -7 activation and apoptosis, suggesting the mediation of LH-induced caspase activation by P450scc. Supplementing pregnenolone, the product of P450scc catalysis, to follicles treated with aminoglutethimide did not restore LH-induced caspase activation. On the other hand, treatment with antioxidants inhibited LH-induced caspase activation. Moreover, LH treatment was associated with an increase in reactive oxygen species which was inhibited by aminoglutethimide. Thus, P450scc catalysis results in an increase in reactive oxygen species, which in turn may trigger/facilitate caspase-3 activation. Finally, we found that in rat corpora lutea in vivo, an increase in steroidogenesis was accompanied by an increase in caspase activity. Thus, this study reveals a linkage between two seemingly distinct processes in which LH-induced caspase activation in cultured rat preovulatory follicles is coupled to mitochondrial steroidogenesis via P450scc.
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PMID:Luteinizing hormone-induced caspase activation in rat preovulatory follicles is coupled to mitochondrial steroidogenesis. 1721 6


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