Effects of curcumin on Wnt/β-catenin, Hedgehog pathways and expression of EMT transcription factors in basal conditions and upon HIF1A and RELA knockdown in HeLa cells

Targeting the HIF1A and NF-κB pathways with pharmacological inhibitors or small interfering RNAs is one of the most promising aspects of cancer stem cell therapy. However, the influence of HIF1A and NF-κB modulators on downstream targets such as components of the Wnt/β-catenin and Hedgehog pathways and EMT is still poorly understood. HeLa cells were treated with 10 and 50 μM curcumin for 24 h, and the function of the Wnt/β-catenin and Hedgehog pathways and EMT transcription factors were subsequently assessed using 14 RNA expression qPCR-based analysis. We also applied siRNA-dependent HIF1A and RELA knockdown to investigate the influence of these pathways on the expression of the above RNAs along and in combination with curcumin treatment. At the higher concentration under basal conditions, curcumin suppressed most of the targets studied, while causing a significant increase in SNAI1 expression. Knockdown of HIF1A and RELA reduced the expression of Hedgehog pathway targets. In contrast to basal conditions, the expression of EMT transcription factors appeared to be increased after knockdown in response to 50 μM curcumin. Curcumin significantly inhibited Wnt/β-catenin, Hedgehog pathways and EMT transcription factor, while inducing an increase in SNAI1 gene expression, which may be part of cell adaptation systems. Knockdown of HIF1A and RELA revealed the strong dependence of Hedgehog target expression on HIF1A and NF-κB pathways. The activation status of HIF1A and NF-κB pathways determines the expression pattern of EMT transcription factors in HeLa cells.