Pigment Epithelium-Derived Factor (PEDF): A Multifaceted and Functional New Therapeutic Agent
Abstract
Pigment epithelium-derived factor, a noninhibitory member of the serine protease inhibitor (serpin) family, is a naturally-occurring protein. The gene encoding human pigment epithelium-derived factor was localized to 17th chromosome and is around 16 kb. Mature gene product is 50 kDa and secreted as a soluable monomeric glycoprotein. Current studies show that pigment epithelium-derived factor is not only found in retinal pigment epithelium cells, but also widely expressed throughout the human body and in the tissues of almost all mammals. Pigment epithelium-derived factor was first discovered as a neurotrophic factor, an inducer of retinoblastoma cell differentiation, secreted by retinal pigment epithelial cells. Later, multiple and varied biological activities of pigment epithelium-derived factor have been found. The unique medicinal properties of this interesting protein are; anti-angiogenesis, anti-proliferative, tumor cell differentiation, anti-oxidant, and neuroprotective effects. Due to all these effects, recently pigment epithelium-derived factor has become the focus of attention of research topics. Today, studies focus on pigment epithelium-derived factor’s indirect (anti-angiogenesis) and direct antitumor effects (inhibiting cell division, tumor invasion and metastasis, promoting tumor cell apoptosis and differentiation). Thus, it is an emerging anti-tumor agent that may be able to target tumor cells and may be used instead of conventional chemotherapy in the future. In this review; briefly the structure and functions of pigment epithelium-derived factor, and the mechanisms in which pigment epithelium-derived factor plays an active role will be discussed.
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References
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