Carlet et al. BMC Cancer 2010, 10:638 http://www.biomedcentral.com/1471-2407/10/638 R E S E A R C H A R T I C L E Open Access Expression, regulation and function of phosphofructo-kinase/fructose-biphosphatases (PFKFBs) in glucocorticoid-induced apoptosis of acute lymphoblastic leukemia cells Michela Carlet1,7, Kristina Janjetovic1,7, Johannes Rainer1,2,7, Stefan Schmidt2,3,7, Renate Panzer-Grümayer4,7, Georg Mann4,7, Martina Prelog5,7, Bernhard Meister6,7, Christian Ploner1,7*, Reinhard Kofler1,2,7 Abstract Background: Glucocorticoids (GCs) cause apoptosis and cell cycle arrest in lymphoid cells and constitute a central component in the therapy of lymphoid malignancies, most notably childhood acute lymphoblastic leukemia (ALL). PFKFB2 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-2), a kinase controlling glucose metabolism, was identified by us previously as a GC response gene in expression profiling analyses performed in children with ALL during initial systemic GC mono-therapy. Since deregulation of glucose metabolism has been implicated in apoptosis induction, this gene and its relatives, PFKFB1, 3, and 4, were further analyzed. Methods: Gene expression analyses of isolated lymphoblasts were performed on Affymetrix HGU133 Plus 2.0 microarrays. GCRMA normalized microarray data were analyzed using R-Bioconductor packages version 2.5. Functional gene analyses of PFKFB2-15A and -15B isoforms were performed by conditional gene over-expression experiments in the GC-sensitive T-ALL model CCRF-CEM. Results: Expression analyses in additional ALL children, non-leukemic individuals and leukemic cell lines confirmed frequent PFKFB2 induction by GC in most systems sensitive to GC-induced apoptosis, particularly T-ALL cells. The 3 other family members, in contrast, were either absent or only weakly expressed (PFKFB1 and 4) or not induced by GC (PFKFB3). Conditional PFKFB2 over-expression in the CCRF-CEM T-ALL in vitro model revealed that its 2 splice variants (PFKFB2-15A and PFKFB2-15B) had no detectable effect on cell survival. Moreover, neither PFKFB2 splice variant significantly affected sensitivity to, or kinetics of, GC-induced apoptosis. Conclusions: Our data suggest that, at least in the model system investigated, PFKFB2 is not an essential upstream regulator of the anti-leukemic effects of GC. Background Glucocorticoid (GC)-induced apoptosis is a phenom- enon of considerable physiologic and therapeutic signifi- cance. Physiologically, it has been implicated in the shaping of the immune repertoire and controlling immune responses, and therapeutically it has been exploited in the treatment of lymphoid malignancies, most notably childhood acute lymphoblastic leukemia * Correspondence: Christian.Ploner@i-med.ac.at 1Division Molecular Pathophysiology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria Full list of author information is available at the end of the article (ALL), where good response to introductory hormone treatment predicts a favourable over-all outcome [1]. GCs mediate most of their effects via their cognate receptor (GR), a ligand-activated transcription factor of the large nuclear transcription factor family. GC-induced apoptosis critically depends on sufficient levels of GR and subsequent alteration in gene expression, but the precise nature of the GC-regulated genes responsible for the anti-leukemic GC effects remains elusive (for reviews see) [1-4]. To further address this issue, we previously exploited a comparative expression profiling strategy using “whole © 2010 Carlet et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.