Protein May Be Marker for Breast Metastasis

Researchers have identified a protein fragment in some breast cancers that correlates closely with lymph node metastasis and earlier recurrence of disease.

Called p95HER-2, the fragment was discovered in the laboratory of Gail Clinton, Ph.D., professor of biochemistry and molecular biology at the Oregon Health & Science University School of Medicine (Portland, OR, USA), in collaboration with investigators in Spain, led by Jose Baselga, M.D.

The study builds on findings published over the last five years about the role of the HER-2 oncogene in breast cancer. HER-2, a growth factor receptor, is overexpressed in 20-30% of breast cancer cases but has limited usefulness in predicting clinical outcomes, especially in early-stage breast cancer.

Dr. Clinton's lab identified a fragment of full-length p185HER-2 that results from HER-2 cleavage, called p95HER-2, and developed an antibody that recognized it, enabling the team to study the role of p95HER-2 in the spread of breast cancer. After studying breast cancer tissue from 483 biopsies, two forms of the HER-2 protein were investigated: the full-length p185HER-2 receptor and its truncated form, p95HER-2. Only the truncated form proved to be a significant independent prognostic factor regarding clinical outcomes. The findings were reported in the January 15, 2006, issue of Clinical Cancer Research.

"More work is needed to determine if the presence of p95 has any significance regarding responsiveness of the cancers to chemotherapy, anti-estrogen therapy, or Herceptin,” said Edward Keenan, Ph.D., one of the study's authors. "Hopefully, understanding the significance of this marker will help us better specify effective therapy for individual patients.”




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