Interleukin-1β regulates the migratory potential of MDAMB231 breast cancer cells through the hypoxia-inducible factor-1α

The casual relationship between inflammation and tumour progression has been widely accepted and the etiology of breast cancer has been associated with inflammatory processes. Interleukin (IL)-1β, besides its central role in inflammation, has also been recognised as a powerful player in tumour progression, angiogenesis and invasiveness. Recently, there has been considerable interest in understanding the non-hypoxic upregulation of the hypoxia-inducible factor (HIF)-1α by IL-1 in neoplastic cells since aberrant expression of HIF-1α correlates with tumour progression. Here, using the highly invasive human breast cancer cell line MDAMB231, we studied the effect of IL-1β on tumour cell migration along with HIF-1α accumulation. We observed that non-hypoxic induction of HIF-1α by IL-1β in MDAMB231 was associated with increased cell migration, paralleled by upregulation of p38 MAPK phosphorylation and CXCL8/CXCR1 expression. Inhibition of HIF-1α by siRNA resulted in a significant reduction of CXCR1 expression and IL-1β-induced cell migration in MDAMB231 cells, thus confirming a role of HIF-1α in the non-hypoxic-IL-1β-dependent induction of migratory potentials. Our observation that IL-1 induces HIF-1α accumulation in MDAMB231 cells was confirmed in tumour cells growing in vivo using an experimental approach, mimicking the endogenous release of IL-1 in mice bearing MDAMB231 xenografts. Our in vivo data, along with the fact that inhibition of HIF-1α resulted in the decrease of IL-1β-promoted cell migration, further support the link between inflammation and cancer. The overall results may have important implications in those therapeutic approaches aimed to inhibit IL-1-mediated activities in tumour cells, specifically in breast cancer.