Various factors such as apoptosis,[1] overcrowding,[4] pathogens[6] and replicative stress[2] can trigger extrusion from epithelia.Additionally, cells transformed with oncogenic mutations such as HRAS[7] and Src can be ejected from epithelia by a similar extrusion process called Epithelial Defense Against Cancer (EDAC).[15] Cells transformed with KRas, a driver of pancreatic, and some types of lung and colon cancer, have unregulated autophagy, which degrades S1P and prevents apical extrusion.[5] Rescue of S1P2 alone is sufficient to reduce orthotopic pancreatic cancer and metastases in a mouse model.When epithelia experience pathological crowding, as airway epithelial do during an asthma attack, they can extrude at such high rates that it destroys the barrier they should provide.
A cell being extruded from an epithelium, with actin in red, microtubules in green, and DNA in blue.
