Abstract
Imatinib mesylate (imatinib, Gleevec®, Novartis, Basel, Switzerland) inhibits T cells in vitro and in vivo (
Dietz et al., Blood 104: 1094–1099, 2004
; Cwynarski et al., Leukemia 18: 1332–1339, 2004
). The drug blocks T cell cycle progression rather uniquely as it neither inhibits expression of CD69, an early marker of T cell activation, nor induces apoptosis. To characterize the molecular effects of imatinib leading to this mode of T-cell inhibition, we measured the changes in transcriptome (by Affymetrix U133 chips), proteome and phosphoproteome (by Western blotting, differential phosphoprotein expression and mass spectrometry). We found that phytohemagglutinin activated T cells pre-treated with imatinib had reduced expression of 983 transcripts and increased expression of 271 transcripts when compared to untreated PHA activated T cells by the factor of 1.5 or more (p<0.05). Among the prominently down-regulated transcripts were granzyme B, CTLA-4 and IL-2-receptor α-chain (CD25), all characteristic of activated T cells, as well as cyclins D2 and D3 and cyclin-dependent kinases 3, 4 and 7, the molecules regulating cell cycle progression. Among the up-regulated transcripts were Kruppel-like transcription factors 2 and 7, and p27, a finding compatible with the observed cell cycle inhibition. Furthermore, we selected and identified 30 proteins from 2-D gels that were up-regulated and/or hyperphosphorylated in imatinib treated activated T cells. Among these were four heterogeneous ribonucleoproteins, three lamins and γ-actin, all components of the nucleoskeleton at the interface of chromatin and inner nuclear membrane and involved in replication and transcription (Herrmann and Foisner, Cell. Mol. Life Sci. 60: 1607–1612, 2003
; Shumaker et al. Curr. Opinion Cell Biol. 15: 358–366, 2003
). Thus, imatinib-borne interference with T cell signal transduction affects the nuclear structure indicating for the first time that nucleoskeleton structural changes are associated with T cell activation status.Author notes
Corresponding author
2005, The American Society of Hematology
2004
