Regulation of HGF and c-MET Interaction in Normal Ovary and Ovarian Cancer.

Binding of hepatocyte growth factor (HGF) to the c-MET receptor has mitogenic, motogenic, and morphogenic effects on cells. The versatile biological effects of HGF and c-MET interactions make them important contributors to the development of malignant tumors. We and others have demonstrated a therapeutic value in targeting the interaction of c-MET and HGF in epithelial ovarian cancer (EOC). However, both HGF and c-MET are expressed in the normal ovary as well. Therefore, it is important to understand the differences in mechanisms that control HGF signaling activation and its functional role in the normal ovary and EOC. In the normal ovary, HGF signaling may be under hormonal regulation. During ovulation, HGF-converting proteases are secreted and the subsequent activation of HGF signaling enhances the proliferation of ovarian surface epithelium in order to replenish the area damaged due to expulsion of the ovum. In contrast, EOC cells that exhibit epithelial characteristics constitutively express both c-MET and HGF-converting proteases such as urokinase-type plasminogen activator. In EOC, mechanisms to control the activation of HGF signaling are absent since HGF is provided locally from the tissue microenvironment as well as remotely throughout the body. Potential incessant HGF signaling in EOC may lead to an increase in proliferation, invasion through the stroma, and migration to other tissues of cancer cells. Therefore, targeting the interaction of c-MET and HGF would be beneficial in treating EOC.