Researchers have now found a new protein that signals the breast cancer tumor to move and spread to other tissue. This finding may help researchers better understand how the cancer spreads and find a new way to fight cancer.

"While the classical approach to cancer drugs has been to find drugs that kill tumor cells, there recently also is an interest in finding drugs that interrupt metastasis. The hope is that such drugs in combination with conventional therapies may lead to better outcomes in patients," said Kathleen Gallo, a professor in Michigan State University Department of Physiology.

Researchers from Michigan State University have found a key protein called MLK3 (mixed lineage kinase 3) that helps these cancer cells migrate and invade other organs in the body.

When cancer starts spreading to other tissues and organs it becomes very difficult to treat. Cancerous cells from the primary tissue break away and move to other organs like the brain, lung or liver. The spreading of cancer to other organs is called metastasis.

Researchers found that the MLK3 protein helps the tumor spread by adding phosphates to other proteins that are involved in cancer movement.

Researchers were able to show, by studies conducted on animals, that the elimination of this culprit protein or blocking the way it adds phosphates to other molecule can stop the cancer from spreading to other organs.

"While drugs such as chemotherapy kill all cells, research has shown drugs that inhibit kinases often can be effective with fewer side effects," Gallo said.

Specifically, a drug called CEP-1347 that stops the protein from adding phosphates to other proteins was found to be effective in keeping the cancerous cells from migrating.

"Cancer is a very complex collection of diseases, but we believe that certain types of cancers may be sensitive to MLK inhibitors and targeting MLK3 may provide a very useful weapon in the fight against cancer," Gallo said.

Researchers say that MLK3 belongs to a type of proteins called as the "protein kinases" whose primary function is to modify other types of proteins. They say that previous research has shown that these proteins are good targets for cancer drugs.

"Our research suggests that the intracellular pathways involving MLK3 that control cell movement could provide new targets for the treatment of patients with metastatic cancer. Drugs developed for combating the MLK3 activity may be useful in reducing the spread of breast cancer," Jian Chen from Michigan State University said.

The study was published in the journal Cancer Research.