Cancer Invasion Led by Normal Cells

Nov. 26, 2007 -- Cancers can spread through the body by following normal maintenance cells that unwittingly blaze a trail for tumor cells to follow.

The unexpected finding comes from studies by Erik Sahai, PhD, and colleagues at London-based Cancer Research UK.

Previously, scientists thought that a tumor spread only after cells in the tumor acquired the ability to push through surrounding tissues -- the extracellular matrix. But Sahai and colleagues now show that normally immobile tumor cells move through the extracellular matrix by following normal cells called fibroblasts.

Fibroblasts make and maintain the extracellular matrix. As part of their job, they push through the matrix. Tumor cells, Sahai's team finds, follow the trail the fibroblasts leave behind. This allows the cancer to spread through the body.

The fibroblasts did not make a trail when the researchers blocked certain chemical messengers the cells leave behind. This made it impossible for the cancer cells to follow them.

"This adds to the complexity of how we should think of treatment in terms of what cells we really should target -- the fibroblasts or the cancer cells themselves," Sahai tells WebMD. "This makes us think about anti-invasion strategies in a different way. We need not just consider the cancer cells but the contribution made by their cellular environment."

In their experiments, Sahai and colleagues looked at squamous cell carcinoma (SCC) cells. But they note that other types of cancer cells -- for example, breast and intestinal cancers -- are also able to follow the trails left behind by normal mobile cells.

The researchers report their findings in the Nov. 25 advance online issue of Nature Cell Biology.