CD73 (胞外-5′-核苷酸酶)

CD73 (Ecto-5′-nucleotidase) is a 70-kD glycosylphosphatidyl inositol (GPI)-anchored cell surface protein encoded by the NT5E gene that plays a crucial role in switching on adenosinergic signaling. CD73 is an ectonucleotidase which catalyzes the terminal step in extracellular adenine nucleotide breakdown: the conversion of AMP to adenosine. Adenosine, which binds to a discrete family of cell surface receptors to initiate intracellular signaling cascades, has been shown to be anti-inflammatory and vasorelaxant.

CD73 has both enzymatic and non-enzymatic functions in cells: as a nucleotidase, CD73 catalyzes the hydrolysis of AMP into adenosine and phosphate, and CD73-generated adenosine plays an important role in tumor immunoescape; moreover, CD73 also functions as a signal and adhesive molecule that can regulate cell interaction with extracellular matrix components, such as laminin and fibronectin, to mediate the invasive and metastatic properties of cancers. Both the enzymatic and non-enzymatic functions of CD73 are involved in cancer-associated processes and are not completely independent of each other. There is ample evidence to show that CD73 is a key regulatory molecule in cancer development and is overexpressed in many cancers, including leukemia, glioblastoma, melanoma, ovarian cancer, esophageal cancer, prostate cancer and breast cancer.