Investigating h-Prune activation of Wnt signalling in breast cancer

We have been investigating a novel link between two independent processes linked to breast cancer: Wnt signalling and h-Prune overexpression. The canonical Wnt signalling pathway was activated in 40% to 60% of human breast cancers through mechanisms that are not understood. Similarly, the phosphodiesterase h-Prune was overexpressed or amplified in 54% of breast cancers and was linked to breast tumour progression through unknown mechanisms. We have shown that overexpression of xenopus Prune induced formation of a secondary axis in a standard assay to identify activators of the Wnt signalling pathway. In HEK293 cells, xenopus Prune overexpression induced a 300-fold increase in Wnt/TCF-dependent transcription. Whilst human prune does not appear to be able to activate Wnt signalling as potently as its xenopus homologue, it does synergise with other activators of the pathway to increase TCF-dependent transcription. Here we show whether there is a correlation between overexpression of h-Prune and active Wnt signalling in breast cancer, and whether the synergistic responses described are mediated through the enzymatic activity of prune, or through binding to GSK-3