Fluid shear stress-induced IL-8/CXCR signaling in human ovarian cancer cells

Background: Interleukin-8 (IL-8) released from mechanosensitive cancer cells plays a key role in the inflammation and metastasis of solid carcinomas. In this study, we have explored IL-8 and its receptors signal transduction process of human ovarian cancer cells under conditions of FSS. Methods: After the fluid shear stress was loaded, LightCycler (TM) system and quantitative sandwich ELISA were employed to assay the IL-8 mRNA expression and protein production, respectively. IL-8 reporter gene pEGFP1-IL8USCS was constructed for determining IL-8 gene transcriptional activation through gene transfer and flow cytometric analysis. NF-kappa B nuclear translocation was observed by immunocytofluorescent staining. Western blot was used to examine I kappa B phosphorylation and degradation. RT-PCR, Northern blot and immunofluorescence were used to determine the expression of a cell-surface chemokine receptor CXCR2 at mRNA and protein levels. Results: IL-8 mRNA expression and protein production had biphasic responses to low shear stress (1.5 dyne/cm(2)), with the peaks at 1 and 2 h respectively. There was an increase in enhanced green fluorescent protein expression in pEGFP1-IL8USCS-transfected SKOV3 cells subjected to a fluid shear stress of 1.5 dyne/cm(2) for 2 h. Following the application of shear stress of 1.5 dyne/cm(2), NF-kappa B p65 became detectable in the cell nuclei, and Phosphorylated I kappa B in cell lysates increased significantly. CXCR2, which was constitutively present on the surface of SKOV3 cells, increased following exposure to fluid shear stress for 60 min. Conclusions: Fluid shear stress triggered IL-8/CXCR2 signaling of SKOV3 cells is an early gene activation, and the activation can be mediated through NF-kappa B. This observation suggested that fluid shear stress-induced IL-8 activation and the downstream signal pathways may have an important contribution to the pathogenesis and development of both inflammation and metastasis of ovarian carcinomas.