Abstract
Aberrant expression of the ALK tyrosine kinase as a chimeric protein with nucleophosmin (NPM) and other partners plays a key role in malignant cell transformation of T-lymphocytes and other cells. Here we report that two small-molecule, structurally related, quinazoline-type compounds, WHI-131 and WHI-154, directly inhibit enzymatic activity of NPM/ALK as demonstrated by in vitro kinase assays using a synthetic tyrosine-rich oligopeptide and the kinase itself as the substrates. The inhibition of NPM/ALK activity resulted in malignant T cells in suppression of their growth, induction of apoptosis and inhibition of tyrosine phosphorylation of STAT3, the key effector of the NPM/ALK-induced oncogenesis. We also show that the STAT3 tyrosine phosphorylation is mediated in the malignant T cells by NPM/ALK independently of Jak3 kinase as evidenced by the presence of STAT3 phosphorylation in the NPM/ALK-transfected BaF3 cells that do not express detectable Jak3 and in the NPM/ALK-positive malignant T cells with either Jak3 activity impaired by a pan-Jak or Jak3-selective inhibitor or Jak3 expression abrogated by Jak3 siRNA. The above results represent the 'proof-of-principle' experiments with regard to the ALK enzymatic activity as an attractive therapeutic target in T-cell lymphomas and other malignancies that express the kinase in an active form.
Original language | English |
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Journal | Laboratory Investigation |
Volume | 85 |
Issue number | 12 |
Pages (from-to) | 1544-54 |
Number of pages | 10 |
ISSN | 0023-6837 |
DOIs | |
Publication status | Published - 2005 |