Gene Research Points to New Breast Cancer Treatments

Researchers say they have found a gene linked to breast cancer that could lead to new treatments and help explain why black women are more likely to die of breast cancer than whites.

The gene, called BP1, was found in 80% of the samples of tissue from breast cancer patients, the researchers report in the June issue of the journal Breast Cancer Research.

“We are hoping our results will be especially helpful for African American women,” said Dr. Patricia Berg of the George Washington University Medical Center, who led the study.

Although 57% of samples from white breast cancer patients tested positive for the gene, 89% from black women did, the researchers said.

“Because BP1 is expressed abnormally in breast tumors, it could provide a useful target for therapy,” Berg’s team wrote.

Berg noted that her team tested only 46 samples, but she said the percentages were consistent. Of the nine normal breast samples she has tested, only one has shown “expression,” or activation, of the BP1 gene. She also tested only ductal cancer -- but ductal cancer makes up 80% of malignant cancers.

Berg said that like some other genes linked with cancer, BP1 was activated early in the development of an embryo and turned off later. That is known as a transcription factor.

“This type of gene makes a protein that is like a policeman directing traffic and turns on and turns off other genes,” Berg said.

Her team will now try to find out what those other genes are.

Berg earlier found that BP1 was active in leukemia, particularly a form called acute myeloid leukemia. In AML patients it was found to be very active in children.

A leukemia drug called all-trans-retinoic acid seemed to deactivate BP1 in lab dishes, Berg said, showing that there is a potential for a drug targeting the gene.

“What we want to do is discover whether this gene will be useful for the early detection and treatment of breast cancer,” Berg said. “We found that the gene is active in all three grades of breast tumors, from the earliest to the most advanced. That means it is activated quite early in the process and potentially might be good for early detection.” She said she was working with a colleague to try to develop such a test.

All the estrogen receptor negative tumors that were studied tested positive for the BP1 gene, the researchers said.

Breast cancers fall into two categories -- those that respond to anti-estrogen therapy and those that do not. So-called ER-positive tumors are easier to treat and respond to such popular drugs as tamoxifen.

ER-negative tumors, which make up 40% of breast cancers, do not. BP1 thus might offer a new avenue for treating such tumors, Berg’s team said.

Black women in the U.S. are more likely to have ER-negative tumors, researchers have found. They are also more likely to die of breast cancer.

More than 200,000 U.S. women will develop breast cancer this year, and 40,000 will die of the disease in 2003, according to the American Cancer Society.