Augmentation of NAD(+) by NQO1 attenuates cisplatin-mediated hearing impairment.

Cisplatin (cis-diaminedichloroplatinum-II) is an extensively used chemotherapeutic agent, and one of its most adverse effects is ototoxicity. A number of studies have demonstrated that these effects are related to oxidative stress and DNA damage. However, the precise mechanism underlying cisplatin-associated ototoxicity is still unclear. The cofactor nicotinamide adenine dinucleotide (NAD(+)) has emerged as a key regulator of cellular energy metabolism and homeostasis. Here, we demonstrate for the first time that, in cisplatin-mediated ototoxicity, the levels and activities of SIRT1 are suppressed by the reduction of intracellular NAD(+) levels. We provide evidence that the decrease in SIRT1 activity and expression facilitated by increasing poly(ADP-ribose) transferase (PARP)-1 activation and microRNA-34a through p53 activation aggravates cisplatin-mediated ototoxicity. Moreover, we show that the induction of cellular NAD(+) levels using ß-lapachone (ß-Lap), whose intracellular target is NQO1, prevents the toxic effects of cisplatin through the regulation of PARP-1 and SIRT1 activity. These results suggest that direct modulation of cellular NAD(+) levels by pharmacological agents could be a promising therapeutic approach for protection from cisplatin-induced ototoxicity.

Cordycepin inhibits IL-1beta-induced MMP-1 and MMP-3 expression in rheumatoid arthritis synovial fibroblasts.

OBJECTIVE: MMP is a key enzyme in the degradation of extracellular matrices, and its expression plays important roles in inflammatory diseases. Cordycepin (3'-deoxyadenosine), a bioactive compound of Cordyceps militaris, has been shown to exhibit many pharmacological activities, such as anti-cancer, anti-inflammatory and anti-infection activities. In this study, we aimed at the inhibitory effect of cordycepin on IL-1beta-induced MMP-1 and MMP-3 expression as well as the molecular basis using RA synovial fibroblasts (RASFs). METHODS: RASFs were isolated from synovial tissue obtained from 12 patients with RA and cultured in monolayer. Expression of MMP-1 and MMP-3 was evaluated using western blotting and real-time PCR. Chemokines were analysed by ELISA. The phosphorylation of mitogen-activated protein kinase was measured by western blotting. Electrophoretic mobility shift assay was performed to evaluate binding activities of DNA to nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). RESULTS: Cordycepin inhibited IL-1beta-induced MMP-1 and MMP-3 expressions in RASFs in a dose-dependent manner. Among various chemokines [such as monocyte chemoattractant protein-1 (MCP-1), GRO-alpha, regulated upon activation, normal T-cell expressed and presumably secreted (RANTES) and epithelial neutrophil activating peptide 78 (ENA-78)], cordycepin specifically blocked IL-1beta-induced ENA-78 production in RASF. Moreover, cordycepin significantly inhibited IL-1beta-induced p38/JNK and AP-1 activation, but not extracellular signal-regulated kinase (ERK) and NF-kappaB activation. CONCLUSIONS: Cordycepin is a potent inhibitor of IL-1beta-induced chemokine production and MMP expression and strongly blocks the p38/JNK/AP-1 signalling pathway in RASFs.

Solanum nigrum produces nitric oxide via nuclear factor-kappaB activation in mouse peritoneal macrophages.

Nitric oxide (NO) is an antitumour molecule produced in activated macrophages and Solanum nigrum is a plant used in oriental medicine to treat tumours. In this study using mouse peritoneal macrophages, we have examined the mechanism by which Solanum nigrum regulates NO production. When Solanum nigrum was used in combination with 20 U/ml of recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. The production of NO from rIFN-gamma plus Solanum nigrum-stimulated peritoneal macrophages was decreased by treatment with N-monomethyl-L-arginine or N-tosyl-Phe chloromethyl ketone, an iNOS inhibitor. Additionally, the increased production of NO from rIFN-gamma plus Solanum nigrum-stimulated cells was almost completely inhibited by pretreatment with 100 micromol/l of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappaB (NF-kappaB). Furthermore, Solanum nigrum increased activation of NF-kappaB. These findings suggest that Solanum nigrum increases the production of NO by rIFN-gamma-primed macrophages and NF-kappaB plays a critical role in mediating these effects.

Vibrio vulnificus cytolysin induces superoxide anion-initiated apoptotic signaling pathway in human ECV304 cells.

Previous studies showed that exposure to Vibrio vulnificus cytolysin (VVC) caused characteristic morphologic changes and dysfunction of vascular structures in lung. VVC showed cytotoxicity for mammalian cells in culture and acted as a vascular permeability factor. In this study, the underlying mechanisms of VVC-induced cytotoxicity was investigated on ECV304 cell, a human vascular endothelial cell line. When cells were exposed to 0.4 hemolytic units (HU) of VVC, consecutive apoptotic events were observed; the elevation of superoxide anion (O (-.)(2)), the release of cytochrome c, the activation of caspase-3, the cleavage of poly(ADP-ribose) polymerase, and the DNA fragmentation. The pretreatment with 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), O(-.) 2) scavenger, completely abolished O(-.)(2) levels and downstream apoptotic events. Moreover, pretreatment with cyclosporin A (CsA), a mitochondrial permeability transition inhibitor, was capable of attenuating O(-.)(2)-mediated cytochrome c release and caspase-3 activation, and consequent apoptosis. Apoptosis, as demonstrated by oligonucleosomal DNA fragmentation and fluorescence microscopy, was induced 24 h after VVC treatment, which was also prevented by caspase-3 inhibitor, Ac-DEVD-CHO. Caspase-1 inhibitor, Ac-YVAD-CHO, did not protect ECV 304 cells from apoptosis. These results suggest a scenario where VVC-induced apoptosis is triggered by the generation of O(-.)(2), release of cytochrome c from mitochondria, activation of caspase-3, degradation of poly(ADP-ribose) polymerase, and DNA fragmentation. The induction of apoptosis in endothelial cells by VVC may provide a pivotal mechanism for understanding the pathophysiology of septicemia.

Effect of an extract of the root of Scutellaria baicalensis and its flavonoids on aflatoxin B1 oxidizing cytochrome P450 enzymes.

The inhibition of aflatoxin B1 (AFB1) metabolism by a water extract of the root of Scutellaria baicalensis and its flavonoids was examined in liver microsomes. AFB1 is known to be metabolized to aflatoxin M1 (AFM1), aflatoxin Q1 (AFQ1), and AFB1-8,9-epoxide (AFBO). The water extract potently inhibited the production of AFM1 by cytochrome P450 (CYP)1A1/2 and slightly reduced AFBO formation by CYP1A1/2, CYP2B1, CYP2C11 and CYP3A1/2 in TCDD-treated rat liver microsomes. IC50 values for AFM1 and AFBO formation were 6.8 and 122.4 microg/ml, respectively. Wogonin showed the highest inhibitory activity towards AFM1 formation among the flavonoids isolated from the extract. On the other hand, the extract had no effects on the formation of AFBO and AFQ1 in human liver microsomes, and on the activities of CYP2B1, CYP2C11 and CYP3A1/2 which were detected by hydroxylation patterns of testosterone. These results demonstrated that the extract of the root of Scutellaria baicalensis has a specific inhibitory effect on CYP1A1/2 among CYP enzymes involved in AFB1 metabolism by rat and human microsomes.

Translocational changes of localization of synapsin in axonal sprouts of regenerating rat sciatic nerves after ligation crush injury.

Time-dependent translocational changes of Synapsin I (SyI), a synaptic vesicle-associated phosphoprotein and its involvement in the axonal transport were investigated in the regenerating axonal sprouts. A weak SyI immunoreactivity (IR) was found in the axoplasm of normal axons. Rat sciatic nerves were crush-injured by ligating with 1-0 silk thread at the mid-thigh level and released from the ligation 24 h later. At various times after release, immunocytochemistry was performed. SyI was translocated from the proximal to the distal site of ligation and also involved in the sprouting of regenerating axons. The distribution patterns of SyI IR were changed in the crush-injured nerves. SyI immunoreactive thin processes were strongly appeared in the proximal region from 1 h after release. After 3 h, a very strong IR was expressed. The intense SyI immunoreactive thin processes were elongated distally and were changed the distribution pattern by time-lapse. After 12 h, strong immunoreactive processes were extended to the ligation crush site. At 1 day, a very intense IR was expressed. At 2 days, immunoreactive thin processes extended into the distal region over the ligation crush site and strong IR was observed after 3 days. SyI was accumulated in the proximal region at the early phases after release. These results suggest that SyI may be related to the translocation of vesicles to the elongated membranes by a fast axonal transport in the regenerating sprouts.

Induction of neutralizing antibody against human cytomegalovirus (HCMV) with DNA-mediated immunization of HCMV glycoprotein B in mice.

Immunization was accomplished by inoculating pcGB containing human cytomegalovirus (HCMV) glycoprotein B (gB) gene into BALB/c mice intramuscularly. IgM antibody was detected in all the immunized group. IgG antibody was also found in all the tested mice with a mean peak antibody titer of 1:262 in three-times immunized groups. IgG antibody appeared at 2 weeks postinoculation, raised peak levels at 7 weeks postinoculation and persisted over 6 months. Neutralizing antibody was developed, and the percent reduction of input infectivity in 1:100 diluted sera was 74.5 % in three-times immunized groups. This study suggested that DNA vaccine using the gene encoding HCMV gB is a candidate method for developing immunity to HCMV.

Association of Shc, Cbl, Grb2, and Sos following treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin in primary rat hepatocytes.

c-Src kinases and p21 Ras are known to be implicated in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated signal transduction. However, the effects of TCDD on the molecular interaction of adaptor complex in the protein tyrosine kinase signaling cascade have not been reported. The present study is designed to clarify whether TCDD modulates the molecular interactions of Shc, Cbl, Grb2, and Sos in primary rat hepatocytes. TCDD causes an electrophoretic mobility shift of Sos and increases Sos/Grb2 association. Tyrosine phosphorylated Shc, mainly p52, unloads to the Grb2/Sos complex upon TCDD stimulation. Interestingly, TCDD decreases the tyrosine phosphorylation level of Cbl, although Cbl recruits more Grb2 and Shc proteins by TCDD. These results indicate that TCDD modulates the molecular interaction of adaptor complex proteins including Shc, Grb2, Sos, and Cbl. Furthermore, tyrosine phosphorylation of Cbl may not be critical for interaction of the protein with Grb2 and Shc in the TCDD signaling pathway in primary rat hepatocytes.