Growth factor modulation of p53-mediated growth arrest versus apoptosis

Genes Dev. 1995 Mar 1;9(5):600-11. doi: 10.1101/gad.9.5.600.

Abstract

Irradiation of mammalian cells can cause cell cycle perturbations and apoptotic cell death. We have investigated the modulation of these physiologic end points by growth factor stimulation: irradiation of a murine hematopoietic cell line in the presence of interlekin-3 (IL-3) induces G1 arrest, and irradiation in the absence of IL-3 results in rapid apoptotic cell death. Both of these end points are dependent on p53. Transient removal of IL-3 at the time of irradiation results in decreased clonogenic survival of irradiated cells. The removal of IL-3 results in a failure of the irradiated cells to arrest at the G1 checkpoint, despite induction of p53 and p21WAF1/CIP1, and then the cells enter S-phase where they undergo apoptosis. There are no cytokine-related changes in Bcl-2, Bax, or Bcl-x protein levels that could account for the modulation of G1 arrest versus apoptosis by growth factors. In contrast, rapid p53-independent alterations of basal levels of gadd45 and p21WAF1/CIP1 expression are linked to IL-3 withdrawal, suggesting a potential mechanism for this modulation. Constitutive activation of cytokine-like pathways with induced expression of v-Src or activated c-Raf inhibits the radiation-induced apoptosis and the alterations in p21WAF1/CIP1 and gadd45 expression. These observations suggest additional molecular mechanisms that can contribute to the development of radioresistance and resistance to apoptosis during tumorigenesis and provide an explanation for the observed lack of p53 mutations in some tumor types. In addition, these data suggest that oncogenic changes occurring during multistep tumorigenesis could be classified as those that either enhance or decrease apoptosis tendencies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Apoptosis / radiation effects
  • Bone Marrow Cells
  • Cell Cycle / drug effects
  • Cell Cycle / radiation effects
  • Cell Division / drug effects*
  • Cell Division / radiation effects
  • Cell Line
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / genetics
  • GADD45 Proteins
  • Gamma Rays
  • Gene Expression Regulation / drug effects*
  • Gene Expression Regulation / radiation effects
  • Genes, p53 / genetics
  • Interleukin-3 / pharmacology*
  • Intracellular Signaling Peptides and Proteins
  • Mice
  • Nuclear Proteins*
  • Oncogene Protein pp60(v-src) / genetics
  • Oncogene Protein pp60(v-src) / physiology
  • Oncogene Proteins, Viral / genetics
  • Proteins / genetics
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-mdm2
  • RNA, Messenger / biosynthesis
  • Repressor Proteins*
  • Tumor Suppressor Protein p53 / biosynthesis
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / physiology*

Substances

  • Cdkn1a protein, mouse
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • E6 protein, Human papillomavirus type 16
  • Interleukin-3
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • Oncogene Proteins, Viral
  • Proteins
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Repressor Proteins
  • Tumor Suppressor Protein p53
  • Mdm2 protein, mouse
  • Proto-Oncogene Proteins c-mdm2
  • Oncogene Protein pp60(v-src)