Biologist has identified gene patterns that characterize a biologically distinct subtype of estrogen receptor negative breast tumor

University of North Carolina molecular biologist Charles Perou has identified the pattern of genes that characterize a biologically distinct subtype of estrogen receptor negative breast tumor. Because this tumor subtype is an aggressive tumor, and because it lacks the only two defined targets for chemotherapy (estrogen receptor and HER2 protein), the roughly 15 percent of women with this type of breast cancer have a poorer prognosis than women with other forms of the disease.

On June 14, at the annual meeting of the American Society for Biochemistry and Molecular Biology (ASBMB)/8th International Union of Biochemistry and Molecular Biology Conference (IUBMB) in Boston, Dr. Perou said clinicians have recognized for some time that there were two types of estrogen receptor negative tumors, those with receptors for the HER2 protein and those without it. "But, it was like looking at a building from the outside," he said. "Identifying the patterns of literally hundreds of genes and the proteins they represent lets us walk inside the building and see what's there - and exactly where we could intervene with a treatment."

Dr. Perou's lab is known for its use of genomic approaches to classify human tumors and to understand pathways altered within each tumor subtype. He then works to implement these findings into standard clinical practice. In earlier work reported in 2000, Dr. Perou and colleagues also discovered a previously unsuspected biologically distinct subtype of estrogen positive breast tumor with a very poor outcome, work that does much to explain why a small percentage of estrogen positive tumors do not have a good outcome.

Dr. Perou says the ability to classify tumors into subtypes is made possible by microarray analysis, a technique that allows scientists to examine vast numbers of genes simultaneously. "The power of genomics is that we no longer are limited to looking at the impact of a single gene," says Dr. Perou. "The biomarker for these subtypes is actually a pattern in which hundreds of genes are interacting. Without these biomarkers, the differences between these tumors would not be recognized and therapies could not be matched appropriately."