HER-2/neu (also called erbB-2) is the gene that encodes for the human epidermal growth factor receptor type 2. This receptor is found in moderate levels on some normal cells and as the gene's name implies, it is involved in cellular responses to growth factors. As shown below, binding of the factor under the right conditions can stimulate cell division.
The HER-2/neu gene is amplified in up to 30% of human breast cancers. The increase in the number of copies of the HER-2/neu gene leads to an increase in the expression of the HER2 protein on the cell surface, and is thought to lead to an increase in cell proliferation (shown below).(1) The gene amplification is also thought to affect the response of the tumors to treatment and as well as the ability of the tumor to grow and spread. Overexpression of this gene may make a tumor more aggressive, but may also make the cancer more sensitive to some chemotherapy agents.(2)More on gene amplification.
Tsuda H, Akiyama F, Terasaki H, Hasegawa T, Kurosumi M, Shimadzu M, Yamamori S, Sakamoto G. "Detection of Her-2/neu (c-erb B-2) DNA Amplification in Primary Breast Carcinoma." Cancer (2001). 92(12): 2965-2974. [PUBMED]
Konecny G, Fritz M, Untch M, Lebeau A, Felber M, Lude S, Beryt M, Hepp H, Slamon D, Pegram M. "Her-2/neu Overexpression and in vitro Chemosensitivity to CMF and FEC in Primary Breast Cancer." Breast Cancer Research and Treatment (2001). 69: 53-63. [PUBMED]