TGF-beta induces growth arrest in Burkitt lymphoma cells via transcriptional repression of E2F-1

J Biol Chem. 2009 Jan 16;284(3):1435-42. doi: 10.1074/jbc.M808080200. Epub 2008 Nov 19.

Abstract

Transforming growth factor-beta (TGF-beta) is a potent regulator of tissue homeostasis and can act as both a tumor suppressor and a tumor promoter. The ability to induce cell cycle arrest is a major component of the tumor suppressor function of TGF-beta. Lung, mammary, and skin epithelial cells exhibit a common minimal cytostatic program in response to TGF-beta signaling involving the repression of the growth-promoting factors c-MYC, Id1, Id2, and Id3. Loss of c-MYC expression is a pivotal event in this process, resulting in derepression of the cyclin-dependent kinase inhibitors CDKN1A (p21) and CDKN2B (p15) and ultimately leading to growth arrest. It is not clear, however, which responses are necessary for TGF-beta-mediated growth arrest in other cell types. Here, in human Burkitt lymphoma cells transformed by deregulated c-MYC expression, we demonstrate that efficient TGF-beta-induced cytostasis can occur despite both maintenance of c-MYC levels and a lack of p21 and p15 induction. TGF-beta treatment also results in induction, rather than repression, of Id1 and Id2 expression. In this context, growth arrest correlates with transcriptional repression of E2F-1, and overexpression of E2F-1 in Burkitt lymphoma cells largely overcomes the TGF-beta-mediated G(1) arrest phenotype. These data indicate that deregulation of c-MYC in lymphoma cells does not overcome the tumor suppressor function of TGF-beta and that repression of E2F-1 transcription is sufficient for the efficient induction of cytostasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Burkitt Lymphoma / genetics
  • Burkitt Lymphoma / metabolism*
  • Cell Line, Tumor
  • Cyclin-Dependent Kinase Inhibitor p15 / genetics
  • Cyclin-Dependent Kinase Inhibitor p15 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • E2F1 Transcription Factor / biosynthesis*
  • E2F1 Transcription Factor / genetics
  • G1 Phase / drug effects*
  • G1 Phase / genetics
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / genetics
  • Humans
  • Inhibitor of Differentiation Proteins / genetics
  • Inhibitor of Differentiation Proteins / metabolism
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Transcription, Genetic / drug effects*
  • Transcription, Genetic / genetics
  • Transforming Growth Factor beta / pharmacology*

Substances

  • CDKN1A protein, human
  • CDKN2B protein, human
  • Cyclin-Dependent Kinase Inhibitor p15
  • Cyclin-Dependent Kinase Inhibitor p21
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • Inhibitor of Differentiation Proteins
  • MYC protein, human
  • Proto-Oncogene Proteins c-myc
  • Transforming Growth Factor beta