HIF-1 and NF-κB-mediated upregulation of CXCR1 and CXCR2 expression promotes cell survival in hypoxic prostate cancer cells

PJ Maxwell, R Gallagher, A Seaton, C Wilson, P Scullin… - Oncogene, 2007 - nature.com
PJ Maxwell, R Gallagher, A Seaton, C Wilson, P Scullin, J Pettigrew, IJ Stratford, KJ Williams…
Oncogene, 2007nature.com
Hypoxic cancer cells are resistant to treatment, leading to the selection of cells with a more
malignant phenotype. The expression of interleukin-8 (IL-8) plays an important role in the
tumorigenesis and metastasis of solid tumors including prostate cancer. Recently, we
detected elevated expression of IL-8 and IL-8 receptors in human prostate cancer tissue.
The objective of the current study was to determine whether hypoxia increases IL-8 and IL-8
receptor expression in prostate cancer cells and whether this contributes to a survival …
Abstract
Hypoxic cancer cells are resistant to treatment, leading to the selection of cells with a more malignant phenotype. The expression of interleukin-8 (IL-8) plays an important role in the tumorigenesis and metastasis of solid tumors including prostate cancer. Recently, we detected elevated expression of IL-8 and IL-8 receptors in human prostate cancer tissue. The objective of the current study was to determine whether hypoxia increases IL-8 and IL-8 receptor expression in prostate cancer cells and whether this contributes to a survival advantage in hypoxic cells. IL-8, CXCR1 and CXCR2 messenger RNA (mRNA) expression in PC3 cells was upregulated in response to hypoxia in a time-dependent manner. Elevated IL-8 secretion following hypoxia was detected by enzyme-linked immunosorbent assay, while immunoblotting confirmed elevated receptor expression. Attenuation of hypoxia-inducible factor (HIF-1) and nuclear factor-κB (NF-κB) transcriptional activity using small interfering RNA (siRNA), a HIF-1 dominant-negative and pharmacological inhibitors, abrogated hypoxia-induced transcription of CXCR1 and CXCR2 in PC3 cells. Furthermore, chromatin-IP analysis demonstrated binding of HIF-1 and NF-κB to CXCR1. Finally, inhibition of IL-8 signaling potentiated etoposide-induced cell death in hypoxic PC3 cells. These results suggest that IL-8 signaling confers a survival advantage to hypoxic prostate cancer cells, and therefore, strategies to inhibit IL-8 signaling may sensitize hypoxic tumor cells to conventional treatments.
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