Hedgehog signalling pathway activation in gastrointestinal stromal tumours is mediated by primary cilia.

Gastrointestinal stromal tumour (GIST) is a mesenchymal cancer which derives from interstitial cells of Cajal. To determine whether a relationship between Hedgehog (Hh) signalling pathway and primary cilia exists in GIST tumours is intended here. Immunohistochemical, immunofluorescence and ultrastructural techniques were performed in this study. We show that GIST cells present primary cilia (an antenna-like structure based on microtubules). But, moreover, we prove Hedgehog signalling pathway activation in these tumours (a pathway related with tumoural features such as proliferation, migration or stemness) and we show for the first time that this signalling pathway activation in GIST is mediated by primary cilia, likely in a paracrine way. Thus, primary cilia and Hedgehog signalling would be fundamental in tumoural microenvironment control of GIST cells for their maintenance, differentiation and proliferation.