Biochem/physiol Actions

Human epidermal growth factor receptor 2 (HER2) signaling pathway stimulates cell proliferation and survival in the majority of breast cancers. Thus, overexpression of this protein causes breast cancer. Heterodimer complex of HER2 and phosphatidylinositide 3-kinase (PI3K) is the most potent stimulator of the PI3K/AKT anti-apoptosis pathway. Increased expression of HER2 is also observed in ovarian, colorectal, pancreatic, endometrial and gastric cancers. Trastuzumab, an antibody, works by binding to a domain in the external domain of HER2. This domain is missing in p95, a truncated form of HER2, and hence these cancer cells show resistance to trastuzumab. HER2 protein can be used as a prognostic marker and as a therapeutic option for gynecologic cancers.

General description

Human epidermal growth factor receptor 2 (HER2), or erb-b2 receptor tyrosine kinase 2 (ErbB2) or tyrosine kinase receptor-1 (tkr-1), is encoded by the gene mapped to human chromosome 17. The encoded protein belongs to the epidermal growth factor family of receptor tyrosine kinases (ErbBs). HER2 membrane protein is characterized with a cysteine-rich extracellular ligand-binding domain, a hydrophobic membrane spanning region and an intracellular tyrosine kinase domain. This protein does not have a ligand, and it either forms heterodimers with other family members or homodimer with itself when expressed at very high levels, to get activated. HER2 is expressed at low level in normal tissues, but at high level in breast cancer tissues.

Physical form

Lyophilized from 0.22 µm filtered solution in PBS, pH7.4. Generally 5-8% Mannitol or trehalose is added as a protectant before lyophilization.

Reconstitution

Centrifuge the vial prior to opening. Reconstitute in sterile PBS, pH 7.4 to a concentration of 50 µg/mL. Do not vortex. This solution can be stored at 2-8°C for up to 1 month. For extended storage, it is recommended to store at -20°C.