Researchers Report Tests Link Chemicals and Cancer Genes

Government researchers say they have the first evidence that a cancer-causing chemical directly acts on a piece of genetic material that has the potential to change a normal cell to a cancerous one.

Scientists at the National Cancer Institute’s Frederick (Md.) Cancer Research Facility say the work is the first to illustrate a long-suspected assumption that carcinogens can have a direct effect on so-called cancer genes.

These cancer genes, or oncogenes, are normal genes with a slight variation that causes them to play a role in starting and sustaining cancers. Since their discovery five years ago, oncogenes have been the focus of research into the genetic basis of cancer.

Dr. Mariano Barbacid and colleagues at Frederick say they discovered in rat studies that one dose of a potent cancer-causing chemical triggers a certain normal “ras” gene into becoming an oncogene that plays an early role in developing a breast cancer.

The findings, to be reported in the British scientific journal Nature, will be presented Thursday at a meeting on the genetic aspects of cancer held at the National Bureau of Standards.

“We think this is the first time that anyone has demonstrated a direct reaction between one carcinogen and one oncogene,” Barbacid said in an interview Tuesday. “People have suspected this for a long time.”

Barbacid said the predictability of the oncogene activation leading to breast cancer in young female rats should allow this system to serve as a model for oncogene studies.