Journal: Antioxidants
Article Title: Piperine Attenuates Lithocholic Acid-Stimulated Interleukin-8 by Suppressing Src/EGFR and Reactive Oxygen Species in Human Colorectal Cancer Cells
doi: 10.3390/antiox11030530
Figure Lengend Snippet: Piperine Inhibits LCA-Induced IL-8 Expression by Suppressing the Activation of ERK1/2, Src, AKT, and EGFR Signaling Pathways. ( A ) HCT-116 cells were pretreated with 30 μM concentration of SB-203580 (SB), 30 μM concentration of PD-98059 (PD), and 30 μM concentration of JNKi for 1 h, and incubated with 30 μM concentration of LCA for 4 h. Subsequently, the IL-8 mRNA level was measured through RT-qPCR. ( B ) HCT-116 cells pretreated with 30 μM SB, 30 μM PD, and 30 μM JNKi for 1 h were incubated with 30 μM LCA for 24 h followed by ELISA assay to determine the IL-8 expression level. ( C ) HCT-116 cells were transiently transfected with dominant-negative mutants of MEK-1 (K97 M), JNK (TAM67), or mutant p38 MAPK (mP38), and co-transfected with pGL2-IL-8. After incubation with 30 μM LCA for 4 h, the luciferase activity was measured using a luminometer. ( D ) HCT-116 cells pretreated with 30 μM SB, 30 μM PD, or 30 μM JNKi for 1 h were incubated with 30 μM LCA for 4 h, and cell lysates were analyzed for the phosphorylated and total ERK level using western blotting. ( E ) HCT-116 cells pretreated with 5 mM NAC or 10 μM DPI for 1 h were incubated with 30 μM LCA for 4 h, and cell lysates were analyzed for the phosphorylated and total ERK level using western blotting. ( F ) HCT-116 cells were incubated with 30 μM LCA for 0–60 min, and cell lysates were analyzed for levels of phosphorylated Src, AKT, and EGFR using western blotting. ( G ) HCT-116 cells pretreated with 10 μM AG1478 (AG), 10 μM PP1, 10 μM PP2, and 20 μM LY-294002 (LY) for 1 h were incubated with 30 μM LCA for 4 h. Subsequently, the IL-8 mRNA level was measured using RT-PCR. ( H ) HCT-116 cells pretreated with 10 μM AG, 10 μM PP1, 10 μM PP2, and 20 μM LY for 1 h were incubated with 30 μM LCA for 4 h, and the luciferase activity was measured using a luminometer. ( I ) Cells transfected with si-Con, si-Src, si-EGFR, and si-AKT were incubated with 30 μM LCA for 4 h, and IL-8 mRNA level was measured using RT-PCR. ( J ) Effects of si-Src, si-AKT, and si-EGFR on LCA-stimulated IL-8 promoter activity in CRC cells. Cells transfected with si-Con, si-Src, si-EGFR, and si-AKT were incubated with 30 μM LCA for 4 h, and the luciferase activity was measured using a luminometer. Data represent the mean ± SEM from three experimental trials. * p < 0.05 versus control; # p < 0.05 versus LCA only. ( K ) HCT-116 cells pretreated with piperine in a dose-dependent manner for 1 h were incubated with 30 μM LCA for 30 min, and cell lysates were analyzed for the phosphorylated Src, EGFR, and AKT levels using western blotting.
Article Snippet: The Src family kinase inhibitors (PP2), LY-294002 (LY), SB-203580 (SB), and the JNK inhibitor (JNKi), BAY-11-7082 (BAY), and SN50AG-1478 (AG) were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA).
Techniques: Expressing, Activation Assay, Protein-Protein interactions, Concentration Assay, Incubation, Quantitative RT-PCR, Enzyme-linked Immunosorbent Assay, Transfection, Dominant Negative Mutation, Mutagenesis, Luciferase, Activity Assay, Western Blot, Reverse Transcription Polymerase Chain Reaction, Control