properties of anaplastic lymphoma kinase -diacylglycerol kinase is critical for the mitogenic α Activation of

ABSTRACT. Oncogenic rearrangements of the tyrosine kinase receptor Anaplastic Lymphoma Kinase (ALK), most commonly represented by the nucleophosmin/ALK fusion protein (NPM/ALK), are involved in the pathogenesis of Anaplastic Large Cell Lymphomas (ALCLs). In an effort to identify new intracellular transducers operative in ALK-positive malignancies, we have investigated the potential involvement of diacylglycerol kinase (DGK). Here we show that DGK is constitutively activated in the NPM/ALK positive ALCL–derived cell line Karpas 299 and in NPM/ALK-infected 32D hematopoietic cells. These results were further validated in fibroblastic NIH-3T3 cells expressing a previously described chimeric Epidermal Growth Factor Receptor (EGFR)/ALK molecule that allows dissection of ALK enzymatic function under conditions of controlled ligand-induced activation. In this cell system we also show that ALK-mediated DGK activation is dependent on p60 src tyrosine kinase, with which DGK forms a complex. The specific inhibition of DGK, obtained by cell treatment with R59949, significantly reduced cellular growth in all cell lines. This result was further confirmed in Karpas 299 following specific down-regulation of DGK by RNA interference. Overall our data indicate that DGK activation is involved in the control of ALK-mediated mitogenic properties.From bloodjournal.hematologylibrary.org by guest on June 1, 2013. For personal use only.