The process of popping cells from epithelia is called extrusion, and in normal cells, this leads to cell death to keep the number of cells under control. “Our new study suggests that this oncogene subverts the mechanism of normal cell death to promote invasion.”

Another characteristic of cells with K-Ras mutations is that they consume parts of themselves (a process called autophagy) to keep up with the energy demands of rapid and unchecked cell division that the mutation causes.

“In normal cells that are about to extrude out, large quantities of an important signal called Sphingosine1-Phosphate (S1P) are present. Cells with the K-Ras mutation also produce S1P, but digest it through autophagy, so it cannot do its job and the cells extrude into the tissue,” said Gloria Slattum, doctoral candidate in the Rosenblatt Lab and lead author of the article. “When we blocked autophagy using a common anti-malaria drug called Chloroquine, the cells with K-Ras mutations extruded out of the tissue and died, just as normal cells do.”

The results were published online December 19 in the journal Current Biology.