Instead of killing off cancer cells with toxic drugs, scientists have discovered a molecular pathway that forces them to grow old and die, they said on Wednesday.

Cancer cells spread and grow because they can divide indefinitely, without going through the normal aging process known as senescence.

But a study in mice showed that blocking a gene in this pathway called Skp2 triggered the aging process, causing cancer cells to stop dividing and halting tumor growth.

The finding may offer a new strategy for fighting cancer, Pier Paolo Pandolfi of Harvard Medical School in Boston and colleagues reported in the journal Nature.

For the study, the team used genetically altered mice that develop a form of prostate cancer.

In some of these, they inactivated the Skp2 gene. When the mice reached six months of age, they found those with an inactive Skp2 gene had developed significantly smaller tumors.

When they analyzed the tissues from lymph nodes and the prostate, they found many cells had started to age, and they also found a slow rate of cell division.

This was not the case in mice with normal Skp2 function.

They got a similar effect when they used a Skp2-blocking drug in lab cultures of human prostate cancer cells.

The team said this aging pathway appears to be related to cancer, and not other cells, suggesting that it could be useful in preventing and treating cancer.

Inactivating this gene with drugs could work “towards a ‘pro-senescence’ therapy for cancer prevention and treatment,” Pandolfi and colleagues wrote.

CHICAGO (Reuters)