A New Understanding of Metastasis

By Jane Farrell

In their deadly journey through the body, cancer cells travel much more efficiently than had been previously thought, a new study shows.

Researchers, whose findings were reported in the Proceedings of the National Academy of Sciences, developed a new mathematical formula that they say better reflects the behavior of cells as they travel through 3-D environments.

Until now, scientists working with flat lab dishes believed that malignant cells move through the body in a slow, aimless fashion, resembling an intoxicated person who cannot walk straight. This “drunken” pattern is called a random walk.

The research was supervised by Denis Wirtz, of the departments of Chemical and Biomolecular Engineering, Pathology and Oncology in the Johns Hopkins Whiting School of Engineering and School of Medicine.

He said that the discovery has critical implications for researchers seeking a better understanding of metastasis. “This means that the time these cancer cells need to make their way out of connective tissues is much shorter than previous estimates.”

Co-lead author Pei-Hsun Wu, a postdoctoral fellow, said the Persistent Random Walk math model, developed for characterizing cell movements in flat Petri dishes, was also being used in 3D testing. That, he said, led to questionable results.

“Cells that are moving through a 3D environment seem to be more directional than those moving across a flat…surface,” said co-lead author Anjil Giri. “The unpredictable ‘random walk’ is not prevalent in a 3D environment.”