Chain-terminating mutations in the APC gene lead to alterations in APC RNA and protein concentration

Viviana Gismondi, Paola Stagnaro, Simona Pedemonte, Roberta Biticchi, Silvano Presciuttini, Paola Grammatico, Paola Sala, Lucio Bertario, Joanna Groden, Liliana Varesco

Research output: Contribution to journalArticlepeer-review


APC mutations introduce premature stop codons into the open reading frame of the gene, leading to the formation of truncated tumor suppressor proteins. Both RNA and protein levels are likely to be profoundly altered by such nonsense mutations. To test this hypothesis, Western blotting and RT- PCR strategies were used to characterize mutant and normal APC protein and APC RNA concentrations in lymphoblastoid cell lines from 22 unrelated polyposis patients carrying different APC mutations. Variable levels of truncated APC peptides were observed in 14 of 14 cell lines with APC mutations within exon 15. No truncated APC protein was detected in six of eight cell lines with APC mutations located 5' of exon 15. Mutations located in exon 15 showed mutant RNA underrepresentation in four of eight cell lines, whereas mutations located 5' of exon 15 showed RNA reduction in five of six cell lines. These findings indicate that a two- to threefold decrease in RNA concentration is common when APC alleles carry chain-terminating mutations. They also suggest that the severe decrease of truncated APC protein observed in some cell lines is due to mechanisms acting at the protein level.

Original languageEnglish
Pages (from-to)278-286
Number of pages9
JournalGenes Chromosomes and Cancer
Issue number4
Publication statusPublished - 1998

ASJC Scopus subject areas

  • Cancer Research
  • Genetics


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