CD55, also known as Decay-accelerating factor (DAF) is an inhibitor of the complement system, and is broadly expressed in malignant tumours. In cancer, CD55 has been implicated in tumorigenesis, neoangiogenesis, and metastasis. CD55 may decrease complement mediated tumor cell lysis, inhibit tumor apoptosis, and promote invasive cancer cell motility. These roles in cancer may involve binding to the seven-span transmembrane receptor CD97. In neuroblastoma cells, CD55 contributes to growth of colonies and to invasion of cells, but not to stemness. In neuroblastoma cells, CD55 is upregulated in a small population of cells that are HIF-2alpha positive. This CD55 positive subpopulation is highly invasive and has low adhesion to fibronectin and collagen. In addition, CD55 expression correlates with poor prognosis in neuroblastoma patients.
