The Molecular Genetics of Retinoblastoma

Abstract

Retinoblastoma is a rare, malignant, childhood tumor that is primarily initiated by the inactivation of both alleles of the retinoblastoma tumor susceptibility gene, RB1, in a developing human retinal cell. A rare subset of retinoblastoma is initiated by somatic amplification of the MYCN oncogene in a predisposing retinal cell. Surprisingly the retinoblastoma protein (pRB), encoded by RB1, is an important transcription factor. Cell-cycle control by pRB is mainly accomplished by transcriptional repression of the genes required for cell-cycle progression. Control of differentiation by pRB is achieved by the activation of transcription. Through extensive post-translational modifications and interactions with other proteins, pRB and family members also influence senescence, chromosomal stability, and apoptosis. Almost every type of tumor has disruption in the retinoblastoma pathway associated with tumor progression, but germline mutation of the RB1 gene predisposes children to a 95% specific risk of developing retinoblastoma and a significantly increased risk of second primary tumors, such as osteosarcoma and melanoma. However, retinoblastoma is also characterized by other genomic changes subsequent to RB1 mutation. Keywords: aneuploidy; apoptosis; chromosome instability (CIN); E2F ; LOH ; MYCN ; proband; RB1 ; retinoblast; retinoma; SV40 ; TAg ; tumor suppressor