Elevation of Survivin levels by hematopoietic growth factors occurs in quiescent CD34+ hematopoietic stem and progenitor cells before cell cycle entry

Cell Cycle. Sep-Oct 2002;1(5):322-6.

Abstract

Survivin is a member of the inhibitor of apoptosis protein (IAP) family that is overexpressed during G(2)/M phase in most cancer cells. In contrast, we previously reported that Survivin is expressed throughout the cell cycle in normal CD34(+) hematopoietic stem and progenitor cells stimulated by the combination of Thrombopoietin (Tpo), Stem Cell Factor (SCF) and Flt3 ligand (FL). In order to address whether Survivin expression is specifically up-regulated by hematopoietic growth factors before cell cycle entry, we isolated quiescent CD34(+) cells and investigated Survivin expression in response to growth factor stimulation. Survivin is up-regulated in CD34(+) cells with 2N DNA content following growth factor addition, suggesting it becomes elevated during G(0)/G(1). Survivin is barely detectable in freshly isolated umbilical cord blood (UCB) Ki-67(negative) and Cyclin D(negative) CD34(+) cells, however incubation with Tpo, SCF and FL for 20 hrs results in up-regulation without entry of cells into cell cycle. Culture of G(0) CD34(+) cells isolated based on Hoechst 33342/PyroninY staining with Tpo, SCF and FL for 48 hrs, results in significantly elevated Survivin mRNA and protein levels. Moreover, labeling of fresh G(0) CD34(+) cells with 5-(and 6-) carboxyfluorescein diacetate succinimidyl ester (CFSE) before culture with growth factors for up to 72 hrs, revealed that Survivin expression was elevated in CFSE(bright) G(0) CD34(+) cells, indicating that up-regulation occurred before entry into G1. These results suggest that up-regulation of Survivin expression in CD34(+) cells is an early event in cell cycle entry that is regulated by hematopoietic growth factors and does not simply reflect cell cycle progression and cell division.

MeSH terms

  • Antigens, CD34 / analysis*
  • Apoptosis
  • Cell Cycle
  • Cells, Cultured
  • Cyclin D
  • Cyclins / metabolism
  • Fetal Blood / cytology
  • Hematopoietic Cell Growth Factors / pharmacology*
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / drug effects
  • Hematopoietic Stem Cells / metabolism*
  • Humans
  • Inhibitor of Apoptosis Proteins
  • Ki-67 Antigen / metabolism
  • Microtubule-Associated Proteins / biosynthesis*
  • Neoplasm Proteins
  • Stem Cells / cytology
  • Stem Cells / physiology
  • Survivin

Substances

  • Antigens, CD34
  • BIRC5 protein, human
  • Cyclin D
  • Cyclins
  • Hematopoietic Cell Growth Factors
  • Inhibitor of Apoptosis Proteins
  • Ki-67 Antigen
  • Microtubule-Associated Proteins
  • Neoplasm Proteins
  • Survivin