The feed-forward loop between YB-1 and MYC is essential for multiple myeloma cell survival

Bommert, K.S. et al. (2013) The feed-forward loop between YB-1 and MYC is essential for multiple myeloma cell survival. Leukemia, 27(2), pp. 441-450. (doi: 10.1038/leu.2012.185)

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Y-box binding protein 1 (YB-1) functions as a translational regulator and has been suggested to elevate MYC mRNA translation via an internal ribosome entry segment (IRES) point mutation in multiple myeloma (MM). We show that YB-1-mediated translation of MYC mRNA occurs independently of the reported IRES mutation, as 87 MM patients (n=88) and all tested human MM cell lines (HMCLs) were negative for the mutation. We show for the first time that positive MYC staining predicts YB-1 co-expression in malignant plasma cells and YB-1/MYC co-expression increases from 30% in medullary to 70% in extramedullary MM. YB-1 knockdown in HMCLs reduced both MYC protein levels and MYC mRNA in the polysomal fraction, providing a mechanism by which YB-1 controls MYC translation. MYC transcription of YB-1 is demonstrated in HMCLs as MYC knockdown resulted in reduced YB-1 protein and mRNA levels. Furthermore, MYC activation in non-malignant mouse embryonic fibroblasts (MEFs) increased YB-1 mRNA, clearly indicating that MYC drives YB-1 transcription. Importantly, perturbation of the MYC/YB-1 oncogenic circuit leads to apoptosis in HMCLs. Here, we demonstrate that these two proteins co-regulate each other via combined transcriptional/translational activity establishing their pivotal role in MM cell survival. We therefore suggest that targeting the YB-1/mRNA interaction provides a new strategy for MM drug development.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Murphy, Professor Daniel
Authors: Bommert, K.S., Effenberger, M., Leich, E., Küspert, M., Murphy, D., Langer, C., Moll, R., Janz, S., Mottok, A., Weissbach, S., Rosenwald, A., Bargou, R., and Bommert, K.
College/School:College of Medical Veterinary and Life Sciences > School of Cancer Sciences
Journal Name:Leukemia
ISSN (Online):1476-5551

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