Normal cells need two signals in order to divide: a growth factor protein, and an indication that the cells are attached to the “correct” surface. Researchers have now discovered how these two signals are integrated. Loss of control over the attachment signal may allow cancer cells to grow even when they are not in the correct part of the body.
Andrew Aplin (University of North Carolina at Chapel Hill) and colleagues report in the April 16 issue of The Journal of Cell Biology that growth factors turn on a set of proteins called extracellular-regulated kinases (ERKs). To do their job, active ERKs have to be in the nucleus, the region of the cell that stores DNA. But in cells that are not attached to a surface, active ERKs stay in the cytoplasm, the region outside of the nucleus. Only when cells stick down to an appropriate surface are the ERKs further modified so that they can enter the nucleus and prompt the cell to multiply.
Many cancer cells can grow without contacting anything, or when they are contacting an unusual surface in a different part of the body that they do not usually encounter. The cancer cells may gain this ability by modifying the control of ERK proteins so that the ERK proteins automatically enter the nucleus.
Materials provided by Rockefeller University Press. Note: Content may be edited for style and length.
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