Laboratory Testing for HER2/neu in Breast Carcinoma: An Evolving Strategy to Predict Response to Targeted Therapy

Nils M. Diaz, MD, Interdisciplinary Oncology Program at the H. Lee Moffitt Cancer Center & Research Institute at the University of South Florida, Tampa, Florida. Submitted July 1, 2001; accepted August 9, 2001

Cancer Control. 2001;8(5) 

In This Article

Expression and Overexpression of HER2/neu

The HER2/neu oncogene encodes a transmembrane protein with tyrosine kinase activity. The 185-kd protein is expressed in nonneoplastic breast epithelial cells and other normal cells. When the protein is over-expressed in carcinoma cells, the tyrosine kinase is constitutively activated, leading to increased mitogenic signal tranduction.[5] Between 20%-30% of breast carcinomas overexpress HER2/neu. The protein is overexpressed as a result of HER2/neu gene amplification, ie, the normal complement of one gene per each chromosome 17 is increased.


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