Ceramide produces apoptosis through induction of p27(kip1) by protein phosphatase 2A-dependent Akt dephosphorylation in PC-3 prostate cancer cells.

Ceramide induces cell cycle arrest and apoptotic cell death associated with increased levels of p27(kip1). The aim of this study was to examine the effects of ceramide on p27(kip1) protein levels as a measure of cell cycle arrest and apoptosis. Results showed that ceramide increased p27(kip1) protein levels through activation of protein phosphatase 2A (PP2A) in PC-3 prostate cancer cells.

Potent inhibition of human cytochrome P450 1B1 by tetramethoxystilbene.

Human cytochrome P450 1B1 (CYP1B1) is found mainly in extrahepatic tissues and is overexpressed in a variety of human tumors. Metabolic activation of 17beta-estradiol (E2) to 4-hydroxy E2 by CYP1B1 has been postulated to be an important factor in mammary carcinogenesis. The inhibition of recombinant human CYP1B1 by 2,2',4,6'-tetramethoxystilbene (TMS) was investigated using either the Escherichia coli membranes of recombinant human CYP1B1 coexpressed with human NADPH-P450 reductase or using purified enzyme.

Induction of p27(kip1) by 2,4,3',5'- tetramethoxystilbene is regulated by protein phosphatase 2A-dependent Akt dephosphorylation in PC-3 prostate cancer cells.

trans-Stilbenes induce cytochrome P450 1B1 (CYP1B1) inhibition and cell death. 2,4,3',5' tetramethoxystilbene (TMS), a synthetic trans-stilbene analog, induced apoptotic cell death in PC-3 prostate cancer cells, as evidenced by a decrease in the mitochondrial membrane potential. TMS-induced apoptosis was associated with an increase in the level of cell cycle inhibitor, p27(kip1), through reduction of Akt-mediated Skp2 expression.

Induction of apoptosis by a stilbene analog involves Bax translocation regulated by p38 MAPK and Akt.

trans-Stilbenes have been reported to induce cytochrome P450 1B1 (CYP1B1) inhibition and cell death, however, the molecular mechanisms of the effects are not fully understood. We report here that (1-(2-{3-[2-(2,4-dimethoxy-phenyl)-vinyl]-5-methoxy-phenoxy}ethyl)-1H-imidazole), a synthetic stilbene analog (SA) significantly suppressed TCDD-stimulated CYP1B1 mRNA expression. In HL-60 cells, SA induced apoptosis through activation of p38 MAPK and inactivation of Akt, which in turn activated Bad and mitochondrial death signaling pathway, as evidenced by Bax translocation and cytochrome c release.

Ceramide induces p38 MAPK-dependent apoptosis and Bax translocation via inhibition of Akt in HL-60 cells.

Ceramide induces apoptosis through caspase activation, cytochrome c release, and Bax translocation in HL-60 cells. However, the upstream signal transduction pathways that induce Bax translocation during ceramide-mediated apoptosis have not been well defined yet. In this study, the activation of p38 mitogen-activated protein kinase (MAPK) was found to be critical for the induction of apoptosis and subcellular redistribution of Bax.

Differential gene expression by styrene in rat reproductive tissue.

Styrene is an important industrial chemical that is extensively used in the production of resins, rubbers and fiberglass-reinforced plastics. Exposing male rats to high doses of styrene may produce sperm abnormalities or infertility. To determine the mechanism underlying styrene-mediated toxicity in male reproductive organs, a reverse transcription-polymerase chain reaction (RT-PCR) technology was employed using annealing control primers (ACPs) to identify the differentially expressed genes following styrene treatment in isolated testis of male rats.

Induction of apoptotic cell death by a ceramide analog in PC-3 prostate cancer cells.

Ceramide analogs are potential chemotherapeutic agents. We report that a ceramide analog induces apoptosis in human prostate cancer cells. The ceramide analog induced cell death through an apoptotic mechanism, which was demonstrated by DNA fragmentation, the cleavage of poly ADP ribose polymerase (PARP), and a loss of membrane asymmetry.

Modulation of human cytochrome P450 1B1 expression by 2,4,3',5'-tetramethoxystilbene.

We have previously shown that 2,4,3',5'-tetramethoxystilbene (TMS), a synthetic trans-stilbene analog, is one of the most potently selective inhibitors of recombinant human cytochrome P450 1B1 (CYP1B1) in vitro. In the present studies, the effects of TMS on CYP1B1 expression were investigated in human cancer cells. TMS significantly inhibited CYP1-mediated 7-ethoxyresorufin O-deethylation activity in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced MCF-7 cells or lung microsomes of Sprague-Dawley rats treated with 7,12-dimethylbenz[a]anthracene.

Potentiation of ceramide-induced apoptosis by p27kip1 overexpression.

The cyclin-dependent kinase inhibitor p27kip1 (p27) has been implicated in the regulation of cell cycle and apoptosis. Recently, we have demonstrated that ceramide induces apoptotic cell death associated with increase in the level of p27 in HL-60 cells. In the present study, we showed that overexpression of p27 increases ceramide-induced apoptotic cell death in HL-60 cells.

Potent inhibition of recombinant human cytochrome p-450 1A1 by pentamethoxystilbene.

Previously it was reported that various hydroxystilbene compounds strongly inhibit human cytochrome P-450 1 enzymes and were postulated as candidate chemopreventive agents. In this study, the inhibitory potential of P-450 1 enzyme activities by 3,5,3,4,5-pentamethoxystilbene (PMS), a synthetic stilbene compound, was evaluated with the Escherichia coli (E. coil) membranes of recombinant human cytochrome P-450 1A1, 1A2, or 1B1 coexpressed with human NADPH-P-450 reductase.

Potent inhibition of human cytochrome P450 1 enzymes by dimethoxyphenylvinyl thiophene.

Cytochrome P450 (P450) 1 enzymes such as P450 1A1, 1A2, and 1B1 are known to be involved in the oxidative metabolism of various procarcinogens and are regarded as important target enzymes for cancer chemoprevention. Previously, several hydroxystilbene compounds were reported to inhibit P450 1 enzymes and were rated as candidate chemopreventive agents. In this study, we investigated the inhibitory effect of 2-[2-(3,5-dimethoxyphenyl)vinyl]-thiophene (DMPVT), produced from the chemical modification of oxyresveratrol, on the activities of P450 1 enzymes.

Involvement of Akt in mitochondria-dependent apoptosis induced by a cdc25 phosphatase inhibitor naphthoquinone analog.

Vitamin K-related analogs induce growth inhibition via a cell cycle arrest through cdc25A phosphatase inhibition in various cancer cell lines. We report that 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone (DDN), a naphthoquinone analog, induces mitochondria-dependent apoptosis in human promyelocytic leukemia HL-60 cells. DDN induced cytochrome c release, Bax translocation, cleavage of Bid and Bad, and activation of caspase-3, -8, -9 upon the induction of apoptosis.

Effects of a naphthoquinone analog on tumor growth and apoptosis induction.

Vitamin K-related analogs induce growth inhibition in various cancer cell lines. A naphthoquinone analog, termed 2,3-dichloro-5, 8-dihydroxy-1,4-naphthoquinone (DDN), induces apoptosis in human promyeloid leukemic HL-60 cells, and shows antitumor activity in vivo. Following treatment with DDN, evidence of apoptosis, including DNA fragmentation and cleavage of poly ADP ribose polymerase (PARP), was observed.

Modulation of CYP3A4 expression by ceramide in human colon carcinoma HT-29 cells.

Cytochrome P450 3A4 (CYP3A4) enzyme is responsible for the metabolic activation and inactivation of the majority of clinically used drugs in human liver and intestines. Recent studies have increasingly implicated various inflammatory stimuli to cause changes in the activities and expression levels of CYPs. However, the underlying mechanisms are largely unknown.

Induction of p73beta by a naphthoquinone analog is mediated by E2F-1 and triggers apoptosis in HeLa cells.

Recently, p73 was identified as a structural and functional homolog of p53. The p73 protein activates the transcription of genes downstream of p53 and induces apoptosis when overexpressed in several cell lines, similar to the tumor suppressor p53. However, the extracellular stimuli and molecular mechanisms regulating p73 activity remain to be elucidated.

Induction of apoptosis by 3,4'-dimethoxy-5-hydroxystilbene in human promyeloid leukemic HL-60 cells.

3, 4'-Dimethoxy-5-hydroxystilbene (DMHS) is a hydroxystilbene compound obtained by methylation and acid hydrolysis of piceid (resveratrol-3-O-glucoside) from Polygonum cuspidatum. Herein, we report that DMHS induces programmed cell death or apoptosis in human promyelocytic leukemic HL-60 cells. We found that treatment of HL-60 cells with DMHS suppressed the cell growth in a concentration-dependent manner with an IC50 value of 25 microM.