Expression, regulation and function of phosphofructo-kinase/fructose-biphosphatases (PFKFBs) in glucocorticoid-induced apoptosis of acute lymphoblastic leukemia cells

BMC Cancer. 2010 Nov 23;10:638. doi: 10.1186/1471-2407-10-638.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / therapeutic use*
  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Cell Survival
  • Child
  • Dexamethasone / therapeutic use*
  • Doxycycline / pharmacology
  • Female
  • Gene Expression Profiling / methods
  • Gene Expression Regulation, Enzymologic / drug effects
  • Gene Expression Regulation, Leukemic / drug effects
  • Glucocorticoids / therapeutic use*
  • Humans
  • Jurkat Cells
  • Lymphocytes / drug effects*
  • Lymphocytes / enzymology
  • Lymphocytes / pathology
  • Male
  • Oligonucleotide Array Sequence Analysis
  • Phosphofructokinase-2 / genetics
  • Phosphofructokinase-2 / metabolism*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / drug therapy*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / enzymology
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / genetics
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / pathology
  • Rats
  • Time Factors
  • Transfection

Substances

  • Antineoplastic Agents
  • Glucocorticoids
  • PFKFB4 protein, human
  • Dexamethasone
  • PFKFB2 protein, human
  • PFKFB3 protein, human
  • Phosphofructokinase-2
  • Doxycycline