Credit: A. QUYN/P. APPLETON

Cell Stem Cell 6, 175–181 (2010)

Loss of the directional asymmetry of cell division seen in certain stem-cell populations may give rise to cancer.

Inke Näthke of the University of Dundee, UK, and her colleagues imaged mitotic spindles — the structures that pull replicated DNA apart during cell division — in three dimensions in mouse and human intestinal cells. In the stem-cell compartments, the spindles often oriented perpendicularly to the cell surface facing the intestinal cavity. This arrangement correlated with an asymmetrical distribution of DNA (pictured in green below) during cell division.

But in mice with a mutation linked to colorectal cancer, the spindles in the precancerous intestinal cells showed no bias towards a perpendicular orientation or asymmetrical division. The results suggest that loss of asymmetrical division in these cells contributes to the development of cancer.