CD44 activation in mature B-cell malignancies by a novel recurrent IGH translocation

Blood. 2010 Mar 25;115(12):2458-61. doi: 10.1182/blood-2009-09-238782. Epub 2010 Jan 21.

Abstract

Using inverse polymerase chain reaction, we identified CD44, located on chromosome 11p13, as a novel translocation partner of IGH in 9 of 114 cases of gastric, nongastric extranodal, follicular, and nodal diffuse large B-cell lymphoma (DLBCL). Notably, these translocations involving IGHSmu were detected in follicular lymphomas and exclusively in germinal center B cell-ike (GCB)-DLBCLs. CD44 is not expressed in reactive GC B cells. The IGHSmu/CD44 translocations substitute Smu for the CD44 promoter and remove exon 1 of CD44, resulting in the overexpression of Imu-CD44 hybrid mRNA transcripts activated from derivative 11 that encode a new CD44 variant lacking the leader peptide and with a unique C-terminus (CD44DeltaEx1). When overexpressed in vitro in the CD44(-) GCB-DLBCL cell line BJAB, CD44DeltaEx1-green fluorescent protein localized to the cytoplasm and nucleus, whereas CD44s-green fluorescent protein (standard form) localized to the plasma membrane. The ectopic expression of CD44DeltaEx1 in BJAB cells enhanced their proliferation rate and clonogenic ability, indicating a possible pathogenic role of the translocation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Chromosome Breakpoints
  • Chromosomes, Human, Pair 11
  • Chromosomes, Human, Pair 14
  • Gene Expression Regulation, Neoplastic
  • Green Fluorescent Proteins / genetics
  • Humans
  • Hyaluronan Receptors / genetics*
  • Hyaluronan Receptors / metabolism
  • Immunoglobulin Heavy Chains / genetics*
  • Lymphoma, Follicular / genetics*
  • Lymphoma, Follicular / pathology
  • Lymphoma, Large B-Cell, Diffuse / genetics*
  • Lymphoma, Large B-Cell, Diffuse / pathology
  • Polymerase Chain Reaction
  • Stomach Neoplasms / genetics*
  • Stomach Neoplasms / pathology
  • Translocation, Genetic*

Substances

  • CD44 protein, human
  • Hyaluronan Receptors
  • Immunoglobulin Heavy Chains
  • Green Fluorescent Proteins