Abstract:Therapy with nucleoside reverse transcriptase inhibitors (NRTIs) can be associated with mitochondrial toxicity. In vitro studies have been used to predict the predisposition for and characterize the mechanisms causing mitochondrial toxicity. Metacavir (PNA) is a novel synthetic nucleoside analog for oral administration with potent and specific antiviral activity against hepatitis B virus (HBV). We assessed the potential for mitochondrial toxicity of PNA in long-term cultures of HepG2 hepatoma cells by measurin… Show more
“…Then cells were fixed with 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH7.2) at 4 C for 1 h and subsequently postfixed with 2% osmium tetroxide as described previously. 70 Then cells were dehydrated with sequential washes in ethanol and then embedded in Epon812 (SPI, 02660-AB). The samples were then sectioned with a Reichert-Jung ultracut E ultramicrotome 701704 (Leica, Germany) and stained with uranyl acetate and lead citrate.…”
Section: Transmission Electron Microscopymentioning
The EGFR (epidermal growth factor receptor) signaling pathway is frequently deregulated in many malignancies. Therefore, targeting the EGFR pathway is regarded as a promising strategy for anticancer drug discovery. Herein, we identified a 2-amino-nicotinonitrile compound (w09) as a novel autophagy enhancer, which potently induced macroautophagy/autophagy and consequent apoptosis in gastric cancer cells. Mechanistic studies revealed that EGFR-mediated activation of the RAS-RAF1-MAP2K-MAPK1/3 signaling pathway played a critical role in w09-induced autophagy and apoptosis of gastric cancer cells. Inhibition of the MAPK1/3 pathway with U0126 or blockade of autophagy by specific chemical inhibitors markedly attenuated the effect of w09-mediated growth inhibition and caspase-dependent apoptosis. Furthermore, these conclusions were supported by knockdown of ATG5 or knockout of ATG5 and/or ATG7. Notably, w09 increased the expression of SQSTM1 by transcription, and knockout of SQSTM1 or deleting the LC3-interaction region domain of SQSTM1, significantly inhibited w09-induced PARP1 cleavage, suggesting the central role played by SQSTM1 in w09-induced apoptosis. In addition, in vivo administration of w09 effectively inhibited tumor growth of SGC-7901 xenografts. Hence, our findings not only suggested that activation of the EGFR-RAS-RAF1-MAP2K-MAPK1/3 signaling pathway may play a critical role in w09-induced autophagy and apoptosis, but also imply that induction of autophagic cancer cell death through activation of the EGFR pathway may be a potential therapeutic strategy for EGFR-disregulated gastric tumors.
“…Then cells were fixed with 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH7.2) at 4 C for 1 h and subsequently postfixed with 2% osmium tetroxide as described previously. 70 Then cells were dehydrated with sequential washes in ethanol and then embedded in Epon812 (SPI, 02660-AB). The samples were then sectioned with a Reichert-Jung ultracut E ultramicrotome 701704 (Leica, Germany) and stained with uranyl acetate and lead citrate.…”
Section: Transmission Electron Microscopymentioning
The EGFR (epidermal growth factor receptor) signaling pathway is frequently deregulated in many malignancies. Therefore, targeting the EGFR pathway is regarded as a promising strategy for anticancer drug discovery. Herein, we identified a 2-amino-nicotinonitrile compound (w09) as a novel autophagy enhancer, which potently induced macroautophagy/autophagy and consequent apoptosis in gastric cancer cells. Mechanistic studies revealed that EGFR-mediated activation of the RAS-RAF1-MAP2K-MAPK1/3 signaling pathway played a critical role in w09-induced autophagy and apoptosis of gastric cancer cells. Inhibition of the MAPK1/3 pathway with U0126 or blockade of autophagy by specific chemical inhibitors markedly attenuated the effect of w09-mediated growth inhibition and caspase-dependent apoptosis. Furthermore, these conclusions were supported by knockdown of ATG5 or knockout of ATG5 and/or ATG7. Notably, w09 increased the expression of SQSTM1 by transcription, and knockout of SQSTM1 or deleting the LC3-interaction region domain of SQSTM1, significantly inhibited w09-induced PARP1 cleavage, suggesting the central role played by SQSTM1 in w09-induced apoptosis. In addition, in vivo administration of w09 effectively inhibited tumor growth of SGC-7901 xenografts. Hence, our findings not only suggested that activation of the EGFR-RAS-RAF1-MAP2K-MAPK1/3 signaling pathway may play a critical role in w09-induced autophagy and apoptosis, but also imply that induction of autophagic cancer cell death through activation of the EGFR pathway may be a potential therapeutic strategy for EGFR-disregulated gastric tumors.
“…As reported previously, metacavir did not have a high risk for potential mitochondrial‐related effects in rhesus monkeys after 3 months of intravenous administration (Zeng et al ., ), and no adverse effect was observed in rhesus monkeys which had been repeatedly dosed with 50 mg/kg per day for 6 months (Chen et al ., ). It is reported that the potential ability of metacavir to interfere with mitochondrial functions is low in vitro (Zhang et al ., ). In addition, treatment with metacavir for 3 months did not alter mitochondrial enzyme activity or mtDNA content in Himalayana marmotas (Zhang et al ., ).…”
A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of metacavir and its two metabolites in rat plasma was developed and validated. Tinidazole was used as an internal standard and plasma samples were pretreated with one-step liquid-liquid extraction. In addition, these analytes were separated using an isocratic mobile phase on a reverse-phase C18 column and analyzed by MS in the selected reaction monitoring mode. The monitored precursor to product-ion transitions for metacavir, 2',3'-dideoxyguanosine, O-methylguanine and the internal standard were m/z 266.0 → 166.0, m/z 252.0 → 152.0, m/z 166.0 → 149.0 and m/z 248.0 → 202.0, respectively. The standard curves were found to be linear in the range of 1-1000 ng/mL for metacavir, 5-5000 ng/mL for 2',3'-dideoxyguanosine and 1-1000 ng/mL for O-methylguanine in rat plasma. The precision and accuracy for both within- and between-batch determination of all analytes ranged from 2.83 to 9.19% and from 95.86 to 111.27%, respectively. No significant matrix effect was observed. This developed method was successfully applied to an in vivo pharmacokinetic study after a single intravenous dose of 20 mg/kg metacavir in rats.
“…The antiviral activity of 2 0 ,3 0 -dideoxyguanosine (DoG) against human immunodeficiency virus (HIV) has been examined since 1990 (Busso et al 1990;Jeffrey et al 2014). DoG has also been demonstrated to have anti-duck hepatitis B virus (DHBV) efficacy in vivo (Chen et al 2007) and a favorable safety profile compared to AZT (Zeng et al 2009;Zhang et al 2010Zhang et al , 2011. However, its antiviral activity against different hepadnaviruses remains unclear.…”
2 0 ,3 0-dideoxyguanosine (DoG) has been demonstrated to inhibit duck hepatitis B virus (DHBV) replication in vivo in a duck model of HBV infection. In the current study, the in vitro antiviral effects of DoG on human and animal hepadnaviruses were investigated. Our results showed that DoG effectively inhibited HBV, DHBV, and woodchuck hepatitis virus (WHV) replication in hepatocyte-derived cells in a dose-dependent manner, with 50% effective concentrations (EC 50) of 0.3 ± 0.05, 6.82 ± 0.25, and 23.0 ± 1.5 lmol/L, respectively. Similar to other hepadnaviral DNA polymerase inhibitors, DoG did not alter the levels of intracellular viral RNA but induced the accumulation of a less-than-full-length viral RNA species, which was recently demonstrated to be generated by RNase H cleavage of pgRNA. Furthermore, using a transient transfection assay, DoG showed similar antiviral activity against HBV wild-type, 3TC-resistant rtA181V, and adefovirresistant rtN236T mutants. Our results suggest that DoG has potential as a nucleoside analogue drug with anti-HBV activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.