Journal: Theranostics
Article Title: Celastrol induces ROS-mediated apoptosis via directly targeting peroxiredoxin-2 in gastric cancer cells
doi: 10.7150/thno.46728
Figure Lengend Snippet: Celastrol directly binds to Prdx2 and inhibits its activity. ( A ) Schematic of the procedure for detecting Celastrol-binding proteins. ( B ) Human protein microarrays were probed with biotinylated-Celastrol. Binding was detected by Cy3-labeled streptavidin. Control experiments were carried out with free biotin (green pots showing interacting proteins). ( C ) Pathway enrichment analysis by DAVID. Celastrol showed the strongest binding ability to Prdx proteins. ( D ) Representative Prdx signals from the protein arrays. Signal-to-noise ratios (SNR) are shown (- = free biotin). ( E, F ) The binding affinity of Celastrol with rhPrdx2 and rhPrdx1 were determined by the SPR assay. KD values are shown above the traces. ( G ) Determination of Celastrol binding to rhPrdx2 protein by isothermal titration calorimetry (ITC). ( H ) Molecular interaction between Celastrol and Prxd2 as determined by docking software. Figure showing possible interaction between Celastrol and Cys172 of Prdx2. ( I, J ) Biotinylated-Celastrol interacts with Prdx2 in SGC-7901 cells and tumor tissues from mice implanted with SGC-7901 cells. Lysates were prepared from untreated SGC-7901 cells in culture and untreated mice subcutaneously injected with SGC-7901 cells. Biotinylated-Celastrol (Bio-Cel) was added to streptavidin-agarose beads. Biotin alone was used as a control. Lysates prepared from SGC-7901 cells (I) and tumor tissues from mice (J) were added. Eluent was then loaded on a polyacrylamide gels for immunoblotting. Total lysates were used as an input control. ( K ) Residue Cys172 of Prdx2 protein was mutated to Ala172 and Ser172. Prdx2 variants were probed for Celastrol interaction and compared to wildtype Prdx2, using pull-down assays described in panels I and J. ( L ) Peroxidase activity of rhPrdx2 proteins were monitored by measuring H 2 O 2 levels as described in Methods (n = 3; * P <0.05, ** P <0.01 compared to 0 µM control]. ( M, N ) rhPrdx2 proteins were incubated with Celastrol or Adenanthin for 10 min and peroxidase activity was measured (n = 3; * P <0.05, ** P <0.01, *** P <0.001 compared to control). The IC 50 of compounds against rhPrdx2 activity are shown. ( O ) Peroxidase activity following addition of Celasterol to rhPrdx1 (n = 3; * P <0.05, ** P <0.01 compared to control). IC 50 of Celastrol is shown. ( P ) Cellular Prdx enzyme activity was measured by adding Celastrol to lysate prepared from SGC-7901 cells (n = 3; * P <0.05, ** P <0.01 compared to 0 µM control). The IC 50 value of Celastrol was shown.
Article Snippet: Prdx2 overexpression was carried out with Prdx2 cDNA plasmid (pGV492-GFP-O/E-Prdx2; Shanghai GeneChem Co) and using the same protocol as indicated.
Techniques: Activity Assay, Binding Assay, Labeling, SPR Assay, Isothermal Titration Calorimetry, Software, Injection, Western Blot, Incubation