Pigment Epithelium-derived Factor In Cancer Research Articles

The Various Roles of PEDF in Cancer

Pigment epithelium-derived factor (PEDF) is a natural immunomodulator, anti-inflammatory, anti-angiogenic, anti-tumour growth and anti-metastasis factor, which can enhance tumour response to PEDF but can also conversely have pro-cancerous effects. Inflammation is a major cause of cancer, and it has been proven that PEDF has anti-inflammatory properties. PEDF’s functional activity can be investigated through measuring metastatic and metabolic biomarkers that will be discussed in this review.

The Role of Pigment Epithelium‐Derived Factor’s Anti‐Angiogenic Properties on Tumor Suppression

Pigment epithelium‐derived factor (PEDF) is a multimodal secreted glycoprotein of roughly 50kDa size and 418 amino acids in length and is found in the interphotoreceptor matrix (ICM) that holds a variety of biological functions. It is a member of the non‐inhibitory serpin family and was first identified as a neurotrophic factor in retinal pigment epithelial cells, however, it has also been identified in several tissues throughout the body including the heart, lung, brain, and pancreas. PEDF is highly conserved throughout evolution and is known to possess neurotrophic, neuroprotective, anti‐tumorigenic, anti‐metastatic properties, and anti‐angiogenic properties. Indeed, PEDF is known as one of the most potent naturally occurring anti‐angiogenic agent. Angiogenesis plays a critical role in the development of cancer because it stimulates the formation of new blood vessels which carry blood to the tumor thereby providing it unlimited access to critical nutrients and oxygen needed for sustained growth and metastatic spread. Hence, the ability of PEDF to block angiogenesis highlights its potential as a novel anti‐cancer agent. Apart from inhibiting angiogenesis, PEDF also inhibits cancer cell proliferation and induces programmed cell death (apoptosis) through activation of FasR/FasL death signaling pathway. The importance of PEDF in cancer is validated by the fact that its expression is significantly reduced in several types of cancers and that loss of PEDF expression is associated with aggressive disease and poor overall survival. Indeed, PEDF expression has been shown to be markedly reduced in breast tumors compared with normal breast tissue and loss of PEDF is associated with resistance to anti‐endocrine therapy due to activation of two critical breast cancer proteins; the estrogen receptor (ER) and the Rearranged during Transfection (RET) proteins. The unique biology of the PEDF protein is directly related to its structure. PEDF is asymmetrically charged, one side being highly acidic the other highly basic, giving it a polar structure that has two functional epitopes. The acidic region contains a 34‐mer peptide that interacts with the PEDF‐RA receptor identified in endothelial cells. When this interaction occurs, apoptosis is initiated, epithelial cell migration is blocked, and corneal angiogenesis is induced. On the other hand, the basic region consists of a 44‐mer peptide that interacts with the PEDF‐RN receptor which has been identified on Y‐79 cells, cerebellar and motor neurons, and in the neural retina. When this epitope is activated, PEDF assists in conducting neural differentiation.Support or Funding InformationThe Olathe North MSOE Center for BioMolecular Modeling SMART Team used 3‐D modeling and printing technology to examine structure‐function of PEDF

Therapeutic Potential of Pigment Epithelium-derived Factor in Cancer.

Pigment epithelium-derived factor (PEDF) is one of the serine protease inhibitors with multifunctional properties, which is produced by various types of organs and tissues. There is an accumulating body of evidence that PEDF plays an important role in the maintenance of tissue homeostasis. Indeed, PEDF not only works as an endogenous inhibitor of angiogenesis, but also suppresses oxidative stress, inflammatory and thrombotic reactions in cell culture systems, animal models, and humans. Furthermore, we, along with others, have found that PEDF inhibits proliferation of, and induces apoptotic cell death in, numerous kinds of tumors. In addition, circulating as well as tumor expression levels of PEDF have been inversely associated with tumor growth and metastasis. These observations suggest that supplementation of PEDF proteins and/or enhancement of endogenous PEDF expression could be a novel therapeutic strategy for the treatment of cancer. Therefore, in this paper, we review the effects of PEDF on diverse types of cancer, and discuss its therapeutic perspectives.

In vitro and in vivo biological activity of PEDF against a range of tumors

Background: Pigment epithelium-derived factor (PEDF) is an emerging anti-cancer agent that targets both tumor tissue and its supporting vasculature. These direct and indirect effects of PEDF have been examined in vitro and in vivo for a range of malignancies. Objective: This review seeks to present PEDF as a potential anti-cancer agent with applications across multiple malignancies. We refer closely to experimental methodology whilst still highlighting the clinical significance of PEDF in cancer, drawing on biological findings in vitro and in vivo. Methods: A Pubmed database search was performed limiting the scope of this discussion paper mainly to PEDF's biological role in cancer, specifically lung, breast, prostatic, ovarian and pancreatic carcinomas, melanoma, glioma and osteosarcoma. Conclusions: The biological roles of PEDF are diverse and multidimensional. As an anti-cancer agent, PEDF has great potential as a focused anti-neoplastic therapy against a variety of tumor types.

Expression and purification of functional recombinant human pigment epithelium-derived factor (PEDF) secreted by the yeast Pichia pastoris

Pigment epithelium-derived factor (PEDF) combines neurotrophic, neuroprotective, anti-angiogenic, anti-tumor and neural stem cell self-renewal properties in a single molecule, making this protein a valuable potential therapeutic agent. We herein analyzed the expression of human recombinant full-length PEDF, and its N- and C-terminal regions (amino acids 1–243 and 195–418, respectively) in three mammalian cell lines (HEK-293T, COS-1, and 26HCMsv), and in the yeast Pichia pastoris. The highest production of recombinant PEDF was achieved in P. pastoris which secreted approximately 30 μg of full-length rPEDF, and 47 μg of C-terminal/ml of culture medium. Full-length rPEDF was purified by one-step Ni-chelating high-performance liquid chromatography, recovering almost 70% of secreted rPEDF with a purity of 98.6%. The C-terminal region of PEDF was isolated by low-pressure liquid chromatography, recovering around 4% of the recombinant molecule with a purity of 98%. The N-terminal region of PEDF was not secreted by any expression system assayed. The two isolated recombinant PEDF polypeptides inhibited in vitro endothelial cell migration, and full-length rPEDF also increased cerebellar granule cell survival, thus demonstrating their biological activity. These polypeptides can be used to investigate the therapeutic role of PEDF in cancer, neurodegenerative and ocular diseases, and stem cell-based therapies.