Clue to cancer's spread uncovered

Genetic signature found specifying organs where tumors will metastasize

July 28, 2005|By Delthia Ricks | Delthia Ricks,NEWSDAY

NEW YORK - Offering clues to the often deadly spread of some cancers from one organ to another, scientists in Manhattan have unmasked the genes that trigger breast cancers to invade the lungs, according to an analysis that will be released today.

The finding is considered a landmark because it is proof that a specific genetic signature exists for each type of cancer and the organ to which it spreads.

Writing in today's issue of the journal Nature, scientists at Memorial Sloan-Kettering Cancer Center say their finding helps unlock the secrets of metastasis.

"First and foremost, these findings are about the basic biology of metastasis, and the example we used to investigate it is the metastasis of breast cancer to the lung," said Dr. Gaorav Gupta, one of two lead investigators who uncovered the genetic secrets in a study involving a special breed of mice.

The immuno-compromised animals were infused with human breast cancer cells from a patient who had widespread metastatic breast cancer.

"Using the [mouse] model, we identified a set of genes that we were able to show mediates this process," Gupta said of cancer straying to a specific site.

"Basically, the genes are largely composed of those that are involved in the communication of tumor cells with the environment they are trying to live in."

In short, there is what Gupta calls "cross talk" between the cancer and the lung.

Dr. Bruce Zetter, chief scientific officer of Children's Hospital in Boston and one of the nation's leading experts on cancer metastasis, said the study opens a new window of understanding and adds credence to a 115-year-old theory called "seed and soil," which postulated the reason cancers spread.

"This study is important because it demonstrates that there is a genetic signature that distinguishes metastatic breast cancer cells from nonmetastatic cells. This is something that has been proposed before, but this study shows it in an extremely thoughtful and careful manner," said Zetter, a professor at Harvard Medical School who was not involved in the Sloan-Kettering research.

"They have found why a breast tumor is not only metastatic, but why it is particularly likely to metastasize to the lungs as opposed to the bone or other sites where breast cancer can spread."

"This is, in fact, an age-old question in cancer research. We always knew that specific tumors went to certain sites, but we didn't know which genes dictated where they went."

Gupta said knowing the genetic signature of breast cancer's potential for invading the lungs provides a new target that can help clinicians identify patients whose cancers are likely to invade the lungs and seed new tumors there.

Newsday is a Tribune Publishing newspaper.

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