T-cell independent, B-cell receptor-mediated induction of telomerase activity differs among IGHV mutation-based subgroups of chronic lymphocytic leukemia patients

Blood. 2012 Sep 20;120(12):2438-49. doi: 10.1182/blood-2012-02-409110. Epub 2012 Aug 8.

Abstract

Although B-cell chronic lymphocytic leukemia (B-CLL) clones with unmutated IGHV genes (U-CLL) exhibit greater telomerase activity than those with mutated IGHV genes (M-CLL), the extent to which B-cell receptor (BCR) triggering contributes to telomerase up-regulation is not known. Therefore, we studied the effect of BCR stimulation on modulating telomerase activity. The multivalent BCR ligand, dextran conjugated anti-μ mAb HB57 (HB57-dex), increased telomerase activity and promoted cell survival and proliferation preferentially in U-CLL cases, whereas the PI3K/Akt inhibitor LY294002 blocked HB57-dex induced telomerase activation. Although both U-CLL and M-CLL clones exhibited similar membrane proximal signaling responses to HB57-dex, telomerase activity and cell proliferation, when inducible in M-CLL, differed. B-CLL cells stimulated using bivalent F(ab')(2) -goat anti-μ antibody (goat anti-μ) exhibited higher membrane proximal response in U-CLL than M-CLL cells, whereas telomerase activity, cell survival, and proliferation were induced to lower levels than those induced by HB57-dex. In normal B lymphocytes, HB57-dex induced less protein phosphorylation but more cell proliferation and survival than goat anti-μ. Although both anti-BCR stimuli induced comparable telomerase activity, normal CD5(+) B cells preferentially exhibited higher hTERT positivity than their CD5(-) counterparts. These findings provide an understanding of how BCR-mediated signals impact telomerase modulation in IGHV mutation-based subgroups of B-CLL and normal B cells.

Publication types

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

MeSH terms

  • Adult
  • Cell Survival
  • Cells, Cultured
  • Female
  • Humans
  • Immunoglobulin Heavy Chains / genetics*
  • Immunoglobulin Variable Region / genetics*
  • Leukemia, Lymphocytic, Chronic, B-Cell / genetics*
  • Leukemia, Lymphocytic, Chronic, B-Cell / immunology*
  • Leukemia, Lymphocytic, Chronic, B-Cell / metabolism
  • Male
  • Mutation / genetics*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Antigen, B-Cell / metabolism*
  • Signal Transduction
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • T-Lymphocytes / pathology
  • Telomerase / metabolism*

Substances

  • Immunoglobulin Heavy Chains
  • Immunoglobulin Variable Region
  • Receptors, Antigen, B-Cell
  • Proto-Oncogene Proteins c-akt
  • TERT protein, human
  • Telomerase