New Gene May Explain Most Breast Cancers

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New Gene May Explain Most Breast Cancers

May Offer Screening, Treatment for Women Without Family History of Disease

By Gina Shaw

Reviewed By Michael Smith, MD

WebMD Medical News

Oct. 7, 2002 -- Cancer researchers have discovered a new gene that may be to blame for most breast cancers. The discovery of the gene -- missing in 60% of breast cancer tumors -- could one day lead to new treatments, according to researchers.

Dubbed DBC2, for "deleted in breast cancer," it's one of a class of genes known as "tumor suppressors," which, when functioning normally, prevent the wild proliferation of abnormal cells associated with cancer. This particular gene, and its biological pathway, has never been identified before.

DBC2 may be particularly important because it's one of a very few genes to be implicated in the 90% of breast cancers characterized as "sporadic" -- afflicting women without any family history of the disease.

Only 10% of breast cancers occur in women with a strong family history of the disease. The best-known and best-understood genes previously identified as abnormal in breast cancer, BRCA1 and BRCA2, appear to be involved primarily in inherited disease.

Currently, no genetic tests can help identify women at increased risk for sporadic breast cancer, but the identification of genes like DBC2 may improve prospects for such tests -- and for new treatments.

Researchers at Cold Spring Harbor Laboratories in New York and at the University of Washington in Seattle, working together, found that the DBC2 gene was turned off in close to 60% of breast cancer tumors, as well as in 50% of lung cancer tumors. In contrast, all samples from normal breast and lung tissue had functioning versions of the DBC2 gene.

When functioning, the DBC2 gene leads to the death of cancer cells or stops them from growing. "When we put a functional version of the gene into a breast cancer cell, then the breast cancer stopped growing. DBC2 clearly has some suppressive function in breast cancer," says lead researcher Masaaki Hamaguchi, MD, PhD.

The results of the DBC2 research will be published Oct. 15 in the Proceedings of the National Academy of Sciences. Tests studying how a normal version of DBC2 affects the growth of lung cancer cells are still ongoing.

The study is small, cautions Hamaguchi, which means that more research needs to be done to confirm the findings. "But our preliminary results are very interesting and very exciting. This is a new gene family which has not been studied yet, so it potentially offers more genetic targets for breast cancer treatment," he says.

"If there is a new biological pathway involved in DBC2, this may be a great target for new therapeutic [agents]. Since the activation of DBC2 arrests the growth of breast cancer cells, our hope is that we can use molecules that participate in this previously unknown biological pathway to treat breast cancer. We might also be able to use the gene itself directly in breast cancer, as gene therapy."

Hamaguchi's team is urging other scientists to take up research on the gene in an effort to confirm and expand on their findings. "We mustn't exaggerate the importance of the results, because the sample size is so small," Hamaguchi says. "But this has the potential to be very, very significant for a lot of women."

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