Second step to retinal tumours

摘要

The mutations that cause retinoblastoma are well known, but how they enable the cancer to evade controls on cell division was unclear. Secondary mutations affecting a growth-regulatory pathway have now been identified. Most cancers arise through a two-step process in which an initiating mutation requires further tumour-promoting mutations to instigate the full-blown disease. Retinoblastoma is a childhood cancer of the retina that is one of the few tumour types for which the initiating genetic lesionis known - both copies of the retinoblastoma (Rb) tumour-suppressor gene are inactivated. However, few of the additional tumour-promoting lesions have been identified. On page 61 of this issue, Laurie et al.1 report that amplification of the numbers of MDMX and MDM2 genes occurs frequently in human retinoblastoma. They show that increased expression of MDMX can promote tumour development in genetic models of retinoblastoma in mice. They also show that a drug called nutlin-3, which blocks some actions of MDM proteins, can stop tumour progression in the eye, opening up a promising avenue for the potential treatment of these tumours.