Molecular mechanisms of oncogenic mutations in tumors from patients with bilateral and unilateral retinoblastoma.

AUTOR(ES)

Hogg, A

RESUMO

The RB1 gene from 12 human retinoblastoma tumors has been analyzed exon-by-exon with the single-strand conformation polymorphism technique. Mutations were found in all tumors, and one-third of the tumors had independent mutations in both alleles neither of which were found in the germ line, confirming their true sporadic nature. In the remaining two-thirds of the tumors only one mutation was found, consistent with the loss-of-heterozygosity theory of tumorigenesis. Point mutations, the majority of which were C-->T transitions, were the most common abnormality and usually resulted in the conversion of an arginine codon to a stop codon. Small deletions were the second most common abnormality and most often created a downstream stop codon as the result of a reading frameshift. Deletions and point mutations also affected splice junctions. Direct repeats were present at the breakpoint junctions in the majority of deletions, supporting a slipped-mispairing mechanism. Point mutations generally produced DNA sequences which resulted in perfect homology with endogenous sequences which lay within 14 bp.

Documentos Relacionados

• Identification of RB1 germline mutations in Argentinian families with sporadic bilateral retinoblastoma.
• Spontaneous regression of bilateral retinoblastoma.
• Excess of cancer deaths in grandparents of patients with retinoblastoma.
• X-ray sensitivity of diploid fibroblasts from patients with hereditary or sporadic retinoblastoma.
• Fibroblast radiosensitivity and intraocular fibrovascular proliferation following radiotherapy for bilateral retinoblastoma.