Researchers at St Jude Children's Research Hospital in Memphis, Tenn, have identified the cell that gives rise to retinoblastoma, an eye cancer that is diagnosed each year in about 300 children and adolescents younger than 20 years, according to the National Cancer Institute (Ajioka I et al. Cell. 2007;131:378-390). They found that retinoblastoma can arise from fully matured nerves in the retina called horizontal interneurons.
In their studies, the investigators showed that when the mouse retina has reduced function of Rb proteins, which are important for the differentiation of immature cells, fully differentiated horizontal neurons can multiply and form cancer while maintaining their differentiated state. This disproves the scientific theory that mature nerves cannot multiply like immature cells.
Hampton T. Retinoblastoma Surprise. JAMA. 2007;298(21):2474. doi:10.1001/jama.298.21.2474-d