Clusters of cancer cells get around by moving single file

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In narrow blood vessels, tumor cells go marching one by one.

By unfolding into a cellular chain, clusters of cancer cells can slide through capillary tubes less than 10 micrometers wide, Sam Au of Harvard Medical School and colleagues report April 18 in the Proceedings of the National Academy of Sciences. The cells pass through the tubes in single file, each squeezing into an oblong shape and clinging to a neighbor or two. After arriving in roomier quarters, the cells regroup into round clumps, the scientists report.

Clumps of cancer cells that break off tumors and travel through the bloodstream to new sites in the body are known to spread cancer more efficiently than single cells. Many scientists believed, though, that hefty cell clusters were unable to squeeze through the body’s narrowest blood vessels.

Experiments showed that human breast and prostate cancer cells used this single-file strategy to travel through lab-made tubes, human cell‒lined tubes and the blood vessels of live zebrafish.  These results could offer insights into ways to foil cancer’s spread.