Aberrant splicing of the E-cadherin transcript is a novel mechanism of gene silencing in chronic lymphocytic leukemia cells

Blood. 2009 Nov 5;114(19):4179-85. doi: 10.1182/blood-2009-03-206482. Epub 2009 Sep 10.

Abstract

Premature termination codon (PTC) mutations are due to insertion or deletion of nucleotides causing a frameshift and premature termination codon in RNA. These transcripts are degraded by the nonsense-mediated decay pathway and have a very short half-life. We used a microarray technique to screen for genes that up-regulate their RNA signal upon nonsense-mediated decay pathway blockade in chronic lymphocytic leukemia (CLL) specimens and identified an E-cadherin transcript with PTC. Sequencing revealed an aberrant E-cadherin transcript lacking exon 11, resulting in a frameshift and PTC. The aberrant E-cadherin transcript was also identified in normal B cells, but occurred at a much lower level compared with CLL cells. In CLL specimens, E-cadherin expression was depressed more than 50% in 62% cases (relative to normal B cells). By real-time polymerase chain reaction analysis, the relative amounts of wild-type transcript inversely correlated with amounts of aberrant transcript (P = .018). Ectopic expression of E-cadherin in CLL specimens containing high amounts of aberrant transcript resulted in down-regulation of the wnt-beta-catenin pathway reporter, a pathway known to be up-regulated in CLL. Our data point to a novel mechanism of E-cadherin gene inactivation, with CLL cells displaying a higher proportion of aberrant nonfunctional transcripts and resulting up-regulation of the wnt-beta-catenin pathway.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alternative Splicing* / drug effects
  • B-Lymphocytes / drug effects
  • B-Lymphocytes / metabolism
  • Base Sequence
  • Cadherins / genetics*
  • Codon, Nonsense
  • DNA Primers / genetics
  • Emetine / pharmacology
  • Frameshift Mutation
  • Gene Silencing*
  • Humans
  • In Vitro Techniques
  • Leukemia, Lymphocytic, Chronic, B-Cell / drug therapy
  • Leukemia, Lymphocytic, Chronic, B-Cell / genetics*
  • Leukemia, Lymphocytic, Chronic, B-Cell / metabolism
  • Molecular Sequence Data
  • Oligonucleotide Array Sequence Analysis
  • RNA Helicases
  • RNA, Neoplasm / genetics
  • RNA, Neoplasm / metabolism
  • RNA, Small Interfering / genetics
  • Signal Transduction
  • Trans-Activators / antagonists & inhibitors
  • Trans-Activators / genetics
  • Up-Regulation / drug effects
  • Wnt Proteins / metabolism
  • beta Catenin / metabolism

Substances

  • CTNNB1 protein, human
  • Cadherins
  • Codon, Nonsense
  • DNA Primers
  • RNA, Neoplasm
  • RNA, Small Interfering
  • Trans-Activators
  • Wnt Proteins
  • beta Catenin
  • RNA Helicases
  • UPF1 protein, human
  • Emetine