Vascular endothelial growth factor (VEGF) regulates tumor vascularization in response to hypoxia and inflammatory signals. The polyphenol curcumin is supposed to interfere with inflammation-induced VEGF secretion and might therefore support anti-VEGF-based treatments. We aimed to investigate the interaction between curcumin and the inflammatory cytokine Interleukin-1β (IL-1β) for VEGF secretion in breast cancer cell lines representing major breast cancer subtypes.

VEGF in cell cultures was detected by Western blot and enzyme-linked immunosorbent assay (ELISA). Kinase phosphorylation was investigated by Western blotting. Gene expressions were analyzed by correlation tests. VEGF was evaluated in a retrospective breast cancer cohort by immunohistochemistry. Survival analysis was performed by the Kaplan-Meier algorithm.

VEGF secretion and kinase signaling in response to IL-1β and curcumin varied significantly for the cell lines MCF-7 (Luminal A), SK-BR-3 (HER2/neu+), MDA-MB-231, and UACC-3199 (triple negative breast cancer). All cell lines increased VEGF secretion under hypoxia, but IL-1β increased VEGF secretion only in MCF-7 cells. Curcumin inhibited VEGF secretion in MDA-MB-231, but increased it in MCF-7 and UACC-3199 cells. Curcumin induced phosphorylation of extracellular signal-regulated kinase (ERK) and p38-mitogen-activated protein kinase (p38-MAPK). However, inhibitor experiments demonstrated that ERK was more important for VEGF secretion. In gene expression data from the METABRIC study, no clear correlation of hypoxia-induced factor (HIF1A), IL-1β, and VEGF mRNA expression was observed; however, a suggested crosstalk of hypoxia and inflammatory pathways was observed.

These dissimilar responses of breast cancer cell lines suggest that therapy efficiency with anti-VEGF, anti-IL-1β, or curcumin will also vary within breast cancers.