Eyeing turnorigenesis:: Notch signaling and epigenetic silencing of Rb in Drosophila

Notch signaling plays an essential role in the processes of embryogenesis and cellular differentiation, and it is believed that the oncogenic effects of dysregulated Notch signaling are an anomalous reflection of the normal functions of this cascade. Nonetheless, the cellular events associated with oncogenic Notch signaling have thus far remained elusive. In a recent report, Ferres-Marco et al.((1)) described how they used the Drosphila eye as a model system and found that elevated Notch signaling in combination with activation of components of the Polycomb complex of transcriptional repressors led to metastatic growth of tumors through epigenetic silencing of the Rbf gene. Rbf is the Drosophila homologue of the retinoblastoma tumor-suppressor gene (Rb), thus it represents a novel link between Notch signaling, tumor growth and metastasis.