الفهرس 
OSTEOPON TINOnly 14 pages are availabe for public view
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Abstract
Osteopontin (OPN) is an acidic member of the small integrin-binding ligand N-linked glycoprotein. OPN Described as a monomer ranging in length from 264 to 301 amino acids that undergoes extensive post-translational modification, including phosphorylation, glycosylation and cleavage resulting in molecular mass variants ranging from 25 to 75 kDa. OPN has been found on epithelial cells and in secretions of the gastrointestinal tract, kidneys, thyroid, breast, uterus, placenta and testes. OPN is also expressed by leukocytes, smooth muscle cells and highly metastatic cancer cells
OPN has been reported to be involved in different biological processes. OPN has an important role in tissue repair and cellular regeneration and in development of tissue fibrosis and protection cells from apoptosis. Also it inhibits expression of nitric oxide synthase in both macrophage and renal tubular epithelial cells which is mediator of tissue injury.
It was reported that OPN play an important role in Implantation and placentation and one of the major constituent of the uterine placental microenvironment with influence as component of histotroph and a product that regulate uterine and placental immune cell. OPN levels might be a useful biomarker of steroid sensitivity in children with nephrotic syndrome.
High levels of OPN in breast tumor cell lines appear to corre¬late with a more aggressiveness, lymph node metastases of breast cancer patients and strongly associated with poor survival.
Head and neck squamous cell carcinoma (HNSCC) is a prime example of hypoxic tumors. Hypoxia causes resistance to radiation. OPN found to be inversely correlated with gene of VHL (gene of hypoxia). And more importantly, its concentration could also be measured easily in plasma. Also plasma concentrations of osteopontin in patients with HNSCC are associated with poor outcome after radiotherapy. There is a significant correlation between plasma OPN level and the risk of tumor relapse, aggressive and death in patients with HNSCC.
OPN-CD44 pathway plays an important role in papillary thyroid carcinomas (PTC). Also play role in PTC cell migration and invasiveness. As CD44 is an OPN cell surface receptor, and it is frequently over expressed in neoplastic thyroid cells.
OPN is a tumor marker for colorectal carcinoma correlates with tumor stage. Representative northern blots showed that osteopontin expression increases con¬cordant with advancing tumor stage in the majority of evaluable tumors.
Serum OPN levels were elevated 2,5-folds in sera of patients with pancreatic adenocarcinoma. OPN stimule cancer cell proliferation and progression. Accordingly, OPN has been associated with decreased survival, increased metastatic potential and advanced disease stage in cancer patients.
OPN can be measured by different methods in tissues and body fluids. It is measured by ELISA, Immunohistochemistry (IHC), Western Blotting and Real-Time Polymerase Chain Reaction (RT-PCR).