Cancer epidermal growth hormone receptor

Whereas epidermal growth factor (EGF) enhances the radiosensitivity of human squamous ceU carcinoma cells in vitro (197), addition of EGF to hormone-deprived MCE-7 breast cancer cells prior to irradiation results ia iacreased radioresistance (198). An anti-EGE-receptor monoclonal antibody blocks the abiUty of EGE to enhance growth and radioresistance. Tumor cells, the growth of which is stimulated by EGE, appear to be protected those where growth is iohibited are sensitized (198). 

Another protein hormone, epidermal growth factor, is bound to the extracellular domain of its receptor. A mutated form of the receptor, which lacks the hormone-binding domain, results in the kinase activity being permanently on. This leads to cancer because the cell is signaled to grow at all times—the hallmark of cancer. 

Trastuzumab (Herceptin) is a humanized monoclonal antibody against the HER2/neu (ErbB-2) member of the epidermal growth factor family of cellular receptors. The internal domain of the HER2/neu glycoprotein encodes a tyrosine kinase that activates downstream signals and enhances metastatic potential and inhibits apoptosis. HER2/neu is overexpressed in up to 30% of breast cancers and is associated with clinical resistance to cytotoxic and hormone therapy. A number of mechanisms of action have... 

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