25% of breast tumors have dangerous mechanical conditioning

Most breast tumors are stiffer than surrounding tissue--it's how they were first described over 2400 years ago, and it's how they are routinely caught today. Not all cancer cells are responsive to pathological stiffness, but those that are become mechanically conditioned, which affects thousands of genes. Intriguingly, mechanical conditioning can be encoded in DNA by a mechanism called "mitotic bookmarking," so mechanical conditioning can persist even as cancer cells divide and conquer.

In the experiment shown below, we sorted breast cancer cells based on whether they had lost their mechanical conditioning (left panel) or retained mechanical conditioning long-term (right panel). These time-lapse movies show the cancer cells invading through collagen in 3D using enhanced depth-of-focus imaging. Mechanical conditioning instructs cancer cells to invade, spread, and wreak havoc in patients.