The Molecular Role of Human Epidermal Growth Factor 2 (her2) in Breast Cancer

HER2 overexpression has been observed in 20-30% of breast cancer cases. In addition to main products of HER2 gene, there are other variations, of which, the most important one is Δ16HER2. In principle, although HER2 overexpression is the first step for carcinogenesis, it is not sufficient, and the main reason responsible for breast tumorigenesis is Δ16HER2. This onco-protein, which lacks exon 16, can form stable homodimers remaining active constitutively. Like Δ16HER2, 611-CTF, a specific HER2 carboxy-terminal fragment, expresses a constitutively active homodimers. Therefore, targeting of Δ16HER2 and 611-CTF is the most promising strategy for treating HER2+ breast cancer. Along with inhibitors of HER2 gene products, miRNAs are also novel candidates for treatment of breast malignancy. Several drugs, working against different domains of the HER2 receptor, have been presented for treatment of HER2 positive breast cancers and they can increase mortality in patients.