Factor | Type | Function | Properties | References |
---|---|---|---|---|
VEGF | Angiogenic | Stimulator of angiogenesis | Produced in the eye by retinal pigment epithelial cells Upregulated by hypoxic condition Contains 5 ligands {VEGF-A, B, C, D and placental growth factor (PGF)} Consists of three protein-tyrosine kinases {(VEGFR-1, Flt-1), (VEGFR-2, Flk-1/KDR), (VEGFR-3)} Two non-protein kinase co-receptors: neuropilin-1 and neuropilin-2 | |
EGF & TGF | Angiogenic | Associated with signaling pathway in cancer & enhances cell proliferation process, leads to metastasis besides decreased apoptosis | Binds to VEGF receptors Mitogens for endothelial cells in vitro, in vivo | |
Angiopoietins | Angiogenic | Promotes angiogenesis in the uterus or embryonic vascular development | Paracrine growth factor Contains 4 ligands Angiopoietin 1, 2, 3, 4 (Ang-1, 2, 3, 4) Two corresponding tyrosine-kinase receptors (Tie-1 and Tie-2) | |
FGF | Angiogenic | Stimulates angiogenesis | FGF contains mainly FGF-1 and FGF-2 and it is also called acidic and basic FGF FGF-1 (acidic FGF) and FGF-2 (basic FGF) | [26] |
MMP | Angiogenic | Degradation of the basement membrane | Belongs to the category of soluble and membrane tied proteolytic enzymes | [27] |
PEDF | Anti-angiogenic | Promotes endothelial cell apoptosis | Also known as serpin F1 Secreted by retinal epithelial cells First factor is described for its neurotrophic properties in vitro | |
Prolactin | Anti-angiogenic | Suppresses cell proliferation process also stimulates expression of plasminogen activator inhibitor | N-terminal 16-kDa fragment 16Â K-PRL is a natural inhibitor of ocular angiogenesis | |
Angiostatin | Anti-angiogenic | Inhibits ATP synthesis and that slows down migration of EC and proliferation | It is a fragment of protein plasminogen Plasminogen and angiostatin can be synthesized by corneal layers | [19] |
Vaso inhibins | Anti-angiogenic | It blocks inducers of angiogenesis (VEGF, FGF, etc.) through in vitro and in vivo | It can be generated by various proteases (MMP’s) | [32] |
Endostatin | Anti-angiogenic | Suppresses migration and proliferation of endothelial cells and increases apoptosis | Derived from collagen XVIII | [19] |
Thrombospondin | Anti-angiogenic | Assists in tumor death | First discovered in activated platelets Contains five multifunctional proteins that can bind extracellular calcium that is TSP-1 to TSP-5 | [33] |