Four genes apparently gang up to help breast cancer spread to the lungs, scientists report in Nature.

Silencing those genes may be a new strategy to stop breast cancer from spreading (metastasizing), note the researchers.

They included Joan Massague, PhD, of the Howard Hughes Medical Institute and the Cancer Biology and Genetics Program at New York's Memorial Sloan-Kettering Cancer Center.

Massague's team studied four genes -- the EREG gene, the Cox-2 gene, and the MMP1 and MMP2 genes -- in human breast cancer cells injected into mice.

In some of the cancer cells, all four genes were inactive. Those breast tumors had trouble growing new blood vessels and spreading cancer cells into the mice's lungs.

In other cancer cells, only one of the four genes was inactive. That didn't do much to curb breast cancer from spreading to the mice's lungs.

The four genes are most effective when they work together, the researchers conclude.

Click here to read more: Testing for Breast Cancer Genes

New Treatment?

Additionally, the researchers studied another set of mice injected with human breast cancer cells.

The scientists treated some of the mice with three drugs -- the cancer drug Erbitux, the anti-inflammatory drug Celebrex, and an experimental anti-inflammatory drug -- that together target all four genes.

For comparison, other mice got no drug treatments.

The drug combinations hampered breast cancer from spreading to the mice's lungs, the study shows.

"This really nailed the case that if we can inactivate these genes in concert, it will affect metastasis," Massague says in a Howard Hughes Medical Institute news release.

Next Steps

Massague says clinical trials of the drug combination are being discussed.

However, Massague points out that "there are already treatments to diminish the chance of metastasis in breast cancer, so such trials would have to be designed very carefully to understand how and whether the new drug combination would be of additional benefit."

Further studies should be done to see whether the gene quartet affects breast cancer's spread to other organs, writes Gerhard Christofori, PhD, in an editorial in Nature.

Christofori is a biochemistry professor in the clinical biological sciences department at Switzerland's University of Basel.

Click here to read more: Are You at Risk for Breast Cancer?

This article was reviewed by Louise Chang, MD

SOURCES: Gupta, G. Nature, April 12, 2007; vol 446: pp 765-770. Christofori, G. Nature, April 12, 2007; vol 446: pp 735-736. News release, Memorial Sloan-Kettering Cancer Center. News release, Nature.