ABSTRACT
This study aimed at exploring the molecular mechanism of fibroin peptide in preventing the Aβ25-35-induced neuronal damages in SH-SY5Y cells.MTT was used to detect the effect of fibroin peptide on the changes of the Aβ25-35-induced injuries in SH-SY5Y cells;Western blot was employed to detect the effect of fibroin peptide on the changes of the Aβ25-35-induced hyperphosphorylation of Tau in SH-SY5Y cells;DCFH-DA probe method was used to detect the effect of fibroin peptide on the Aβ-induced production of intracellular reactive oxygen species (ROS) in SH-SY5Y cells.The results indicated that fibroin peptide could improve the activity of the PP2A and inhibit the activity of GSK-3β to decrease the hyperphosphorylation of Tau induced by Aβ25-35.Fibroin peptide could significantly prevent the Aβ25-35-induced neuronal damages and multisite Tau hyperphosphorylation.In addition,fibroin peptide could also reduce oxidative damage to protect neurons by significantly decreasing the Aβ25-35-induced production of intracellular ROS.
ABSTRACT
Aim Our previous study has found that ur-solic acid( UA) increased intracellular reactive oxygen species ( ROS ) production and adenosine monophos-phate-activated protein kinase ( AMPK ) phosphoryla-tion, inhibited signal transducer and activator of tran-scription 3 ( STAT3 ) phosphorylation and cyclooxygen-ase-2 ( COX-2 ) expression in gastric cancer cells . However , the molecular mechanism by which UA in-hibits COX-2 expression in gastric cancer cells has not been fully clarified .In this study we aimed to further clarify the signal transduction pathways involved in the UA-mediated inhibition of COX-2 expression in gastric cancer cells .Methods Human gastric cancer cell lines SGC-7901 and MKN-45 were routinely cultured in RPMI-1640 medium supplemented with 10% heat-in-activated fetal calf serum .Sub-confluent cell cultures were pre-treated with antioxidant N-acetylcysteine ( NAC) , AMPK activator 5-amino-4-imida-zolecarbox-amide-riboside ( AICAR ) , AMPK inhibitor compound C, or STAT3 inhibitor WP1066 and then treated with or without UA for 24 h.The expression of AMPK and phosphorylated AMPK ( p-AMPK ) , STAT3 and phos-phorylated STAT3 ( p-STAT3 ) , as well as COX-2 was detected by Western blot analysis .Results Antioxi-dant NAC and AMPK inhibitor compound C blocked UA-induced inhibition of STAT 3 phosphorylation and down-regulation of COX-2 expression in gastric cancer cells.Both AMPK activator AICAR and UA inhibited STAT3 phosphorylation and COX-2 expression; the combination of two drugs resulted in further reduction . STAT3 inhibitor WP1066 did not affect UA-induced AMPK phosphorylation , whereas it inhibited STAT3 phosphorylation and COX-2 expression .The inhibitory effects on the STAT3 phosphorylation and COX-2 ex-pression were significantly enhanced when SGC-7901 and MKN-45 cells were treated simultaneously with WP1066 plus UA.Conclusion UA inhibits COX-2 expression in gastric cancer cells , which may be medi-ated through ROS/AMPK/STAT3 signal transduction pathway .
ABSTRACT
Objective To investigate the effects of Epigallocatechin gallate(EGCG)on IL-1βinduced MIN6 cells apoptosis. M.Methods The experiment group was divided into control group,IL-1β group,IL-1β+ EGCG low concentration group and IL-1β+EGCG high concentration group.Cell activity was detected by CCK8.Insulin secretion was detected by ELISA.cell apoptosis was detected by flow cytometry.The mitochondrial membrane potential was detected by flow cytometry.ATP content and cell ac-tivity of ROS were detected by colorimetry and chemiluminescence method.Results Compared with normal group,IL-1β group showed much lower cell activity,insulin secretion,cell mitochondrial membrane potential and ATP content,and at the same time IL-1βgroup had significantly higher cell apoptosis and ROS activities.After given EGCG,both low concentration group and high con-centration group had higher cell activity,insulin secretion,cell mitochondrial membrane potential and ATP content,at the same time lower cell apoptosis and ROS activities was showed.And the IL-1β+EGCG high concentration group worked more powerful.Con-clusion EGCG has protective effects on IL-1βinduced MIN6 cells apoptosis.Its mechanism may be related to increasing the content of the ATP and mitochondrial membrane potential and protecting mitochondrial function as well reducing the activity of ROS.
ABSTRACT
Aim To study the mechanisms of the pro-tective effect of procyanidin B2 ( PCB2 ) on the myocar-dial cell apoptosis induced by lipopolysaccharide ( LPS) . Methods Using the primary culture rat myo-cardial cells, myocardial cell injury model was induced by LPS. PCB2 low, medium and high dose groups, were cultured with 6. 25 , 12. 5 , 25. 0 μmol · L-1 PCB2 respectively in DMEM medium for 24 h continu-ously. Myocardial cell survival rate was determined by MTT colorimetric method. Cardiacmyocyte NOX activi-ty was determined by lucigen chemiluminescence meth-od . Western blot analysis was used to detect myocardi-al NADPH oxidase p47phox expression. TUNEL method was used to detect apoptosis and flow cytometry was used to determine the content of myocardial cells ROS. Results Compared with control group, the cell dam-age induced by LPS group myocardial cell survival rate significantly decreased ( P <0. 01 ) , and myocardial cell NOX activity, p47phox expression, apoptotic cell number and ROS content were significantly increased (P<0. 01). PCB2 low, medium and high dose groups cell survival rates were significantly elevated, myocar-dial cell NOX activity and p47phox expression, apoptotic cell number and the ROS content decreased significant-ly in a dose-dependent manner ( P <0. 01 ) . Conclu-sion PCB2 protects myocardial cell apoptosis induced by LPS via inhibiting the expression of NADPH oxidase activation, p47phox expression and reactive oxygen spe-cies generation.