Silencing of the microtubule-associated proteins doublecortin-like and doublecortin-like kinase-long induces apoptosis in neuroblastoma cells

Doublecortin-like kinase-long (DCLK-long) and doublecortin-like (DCL) are two splice variants of DCLK gene. DCL and DCLK-long are microtubule-associated proteins with specific expression in proliferative neural progenitor cells. We have tested the hypothesis that knockdown of DCL/DCLK-long by RNA interference technology will induce cell death in neuroblastoma (NB) cells. First, we analyzed the expression of DCL and DCLK-long in several human neuroblastic tumors, other tumors, and normal tissues, revealing high expression of both DCL and DCLK-long in NB and glioma. Secondly, gene expression profiling revealed numerous differentially expressed genes indicating apoptosis induction after DCL/DCLK-long knockdown in NB cells. Finally, apoptosis was confirmed by time-lapse imaging of phosphatidylserine translocation, caspase-3 activation, live/dead double staining assays, and fluorescence-activated cell sorting. Together, our results suggest that silencing DCL/DCLK-long induces apoptosis in NB cells.