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The t(X;7)(q22;q34) in paediatric T-cell acute lymphoblastic leukaemia results in overexpression of the insulin receptor substrate 4 gene through illegitimate recombination with the T-cell receptor beta locus.

Author:
  • Kristina Karrman
  • Eigil Kjeldsen
  • Carin Lassen
  • Margareth Isaksson
  • Josef Davidsson
  • Anna Andersson
  • Henrik Hasle
  • Thoas Fioretos
  • Bertil Johansson
Publishing year: 2009
Language: English
Pages: 546-551
Publication/Series: British Journal of Haematology
Volume: 144
Document type: Journal article
Publisher: Federation of European Neuroscience Societies and Blackwell Publishing Ltd

Abstract english

Summary The t(X;7)(q22;q34), a translocation not previously reported in a neoplastic disorder, was identified and molecularly characterised in a paediatric T-cell acute lymphoblastic leukaemia (T-ALL), subsequently shown also to harbour a deletion of 6q, a STIL/TAL1 fusion and an activating NOTCH1 mutation. The t(X;7) was further investigated using fluorescence in situ hybridisation (FISH), real-time quantitative polymerase chain reaction (RQ-PCR) and Western blot analyses. FISH revealed a breakpoint at the T-cell receptor beta locus at 7q34 and mapped the corresponding breakpoint to Xq22.3. The latter region contains only two known genes, namely insulin receptor substrate 4 (IRS4) and collagen, type IV, alpha 5 (COL4A5), the expressions of which were analysed by the use of RQ-PCR. COL4A5 was not differentially expressed in the t(X;7)-positive sample compared to five T-ALL controls. However, a marked, 1000-fold overexpression of IRS4 was identified. Western blot analysis with a monoclonal antibody against IRS4 showed overexpression also at the protein level. Considering that forced expression of several members of the IRS family has been shown to result in increased cell proliferation, for example in haematopoietic cells, we hypothesise that the IRS4 up-regulation in T-ALL is pathogenetically important as a mitogenic stimulus.

Keywords

  • Hematology

Other

Published
  • ISSN: 0007-1048
Thoas Fioretos
E-mail: thoas.fioretos [at] med.lu.se

Principal investigator

Translational Genomic and Functional Studies of Leucemia

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66

Professor

Division of Clinical Genetics

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66

Professor

Translational Genomic and Functional Studies of Leucemia

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66