Delicate, threadlike protrusions used by cancer cells when they invade other tissues in the body could also help them escape control mechanisms supposed to eliminate them, a research group led by led by Bradley Davidson in the University of Arizona's department of molecular and cellular biology reports in Nature Cell Biology.
Studying embryos of the sea squirt Ciona intestinalis, the researchers discovered that even non-invasive cells make the delicate, highly transient structures known as invadopodia. The group found that future heart cells in the Ciona embryo use invadopodia to pick up chemical signals from their surroundings. These so-called growth factors provide the cells with clues as to where they are in the developing embryo and what type of cell they are supposed to turn into.
The results suggest that this previously unknown role of invadopodia could also be at play in the case of cancer cells: Their invadopodia may serve to bind similar signaling molecules that protect them from the body's elimination processes, thereby ensuring their survival.
"These are special invasive protrusions and they are seen only in rare cell types and cancer cells. We are the first to see them in the developing Ciona embryo, and we certainly didn't expect to see them in that context," said Davidson, who is a member of UA's Arizona Cancer Center. "In Ciona, the cells that are making these special kinds of arms do not use them for invasion. Those cells behave very differently from cancer cells."
Cells form invadopodia in a process that resembles pitching a tent: They push a portion of their rigid, internal scaffolding into a portion of the cell membrane which envelopes the entire cell, thereby extending a long, thin protrusion outward.
"These structures are extremely fragile. The cells grow and retract them over short periods of time," Davidson said. "For that reason, they are almost impossible to see in fixed speci
|Contact: Daniel Stolte|
University of Arizona