[IL-8 inhibits the apoptosis of MCF-7 human breast cancer cells by up-regulating Bcl-2 and down-regulating caspase-3].

Abstract

OBJECTIVE: To investigate the effect of interleukin-8 (IL-8) on the apoptosis of MCF-7 human breast cancer cells and the molecular mechanism. METHODS: The expressions of IL-8 receptors (CXCR1, CXCR2) in MCF-7 cells were detected by Western blotting. The effects of 0, 20, 40, 80, 160 ng/mL IL-8 on the expressions of apoptosis-related genes Bcl-2 and caspase-3 in MCF-7 cells were observed by reverse transcription PCR(RT-PCR) and Western blotting. Cell proliferation was determined by CCK-8 assay after 0, 40, 80 ng/mL IL-8 treatment. Phase contrast microscope was used to examine cell morphology of MCF-7 cells after 80 ng/mL IL-8 treatment. The effects of 80 ng/mL IL-8 combined with PD980590 (10 μmol/L), LY294002 (10 μmol/L) or AG490 (50 μmol/L) [mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), Janus kinase/signal transducer and activator of transcription (JAK/STAT) signal pathway inhibitors, respectively], on the expression of Bcl-2 were detected by Western blotting. The effects of 0, 20, 40, 80, 160 ng/mL IL-8 on the expression of p-AKT in MCF-7 cells were observed by Western blotting. The effects of 80 ng/mL IL-8 combined with 10 μmol/L LY294002 on the apoptosis of MCF-7 cells, the expressions of Bcl-2 and caspase-3 were determined by flow cytometry, RT-PCR and Western blotting, respectively. RESULTS: Both CXCR1 and CXCR2 were expressed in MCF-7 cells. IL-8 markedly up-regulated the anti-apoptotic gene Bcl-2, down-regulated the pro-apoptotic gene caspase-3, and significantly inhibited the apoptosis of MCF-7 cells. However, these effects were blocked by phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), signal pathway inhibitor LY294002. As predicted, IL-8 markedly increased the expression of p-AKT in MCF-7 cells. CONCLUSION: IL-8 might significantly inhibit the apoptosis of MCF-7 cells. This effect may be achieved by up-regulating Bcl-2 and down-regulating caspase-3 via PI3K/AKT signal pathway.