Notch signaling: a potential therapeutic target in prostate cancer

The Notch pathway and the endocrine system constitute two key biological signaling mechanisms, responsible for cell-to-cell communication between adjacent cells and long-distance hormonal signals respectively. They play central roles during the development of higher eukaryotic organisms but they also take part in the regulation of many aspects of adult physiology and homeostasis. The contribution of defects in the normal transmission of hormone-dependent signals to the development of endocrine cancers has been widely analyzed and the knowledge derived from these studies has allowed us to develop many successful therapeutic strategies. However, in many cases these hormonal treatments become ineffective despite the fact that cancer cells maintain normal expression levels of wild-type hormone nuclear receptors. Less is known about the involvement of altered Notch signaling in the origin and progression of cancer, although there is clear evidence indicating that deregulation of Notch activity occurs in several types of tumors, including highly prevalent hormone-dependent types of cancer such as breast, ovarian and prostate cancer. This review will summarize accumulating data suggesting that Notch signaling plays a key role in the control of proliferation, differentiation and survival of prostate epithelial cells. Notch signals are required for normal prostate development and homeostasis, and abnormalities in Notch signaling may be critical during the development of prostate cancer. We will also discuss the possible oncogenic role for alterations in the crosstalk mechanisms between Notch and androgen-dependent signals during tumorigenesis in the prostate and how they could influence the outcome of anti-cancer hormonal treatments.