Transforming growth factor-β directly induces p53-up-regulated modulator of apoptosis (PUMA) during the rapid induction of apoptosis in myc-driven B-cell lymphomas

J Biol Chem. 2013 Feb 15;288(7):5198-209. doi: 10.1074/jbc.M112.410274. Epub 2012 Dec 14.

Abstract

c-Myc transformed human Burkitt's lymphoma (BL) cells are highly sensitive to TGF-β-induced apoptosis. Previously we demonstrated that TGF-β-mediated cell death in BL cells is regulated via the mitochondrial intrinsic apoptosis pathway, which is dependent on the activation of BAX and/or BAK. TGF-β directly induces transcription of the BH3-only protein BIK and represses expression of the pro-survival factor BCL-X(L) but has no effect on the direct BAX/BAK "activators" BIM or BID (tBID). Here we show that TGF-β induces the BH3-only activator PUMA to aid induction of the intrinsic cell death pathway. TGF-β also induced PUMA in normal germinal center CD77-positive centroblasts isolated from human tonsil tissue. PUMA was a direct TGF-β target gene in B-cells, and we identify a putative Smad-binding region within the human PUMA promoter that recruits Smad3 and Smad4 in cells in response to TGF-β signaling. Constitutive activity of the isolated Smad-binding region in luciferase reporter assays was dependent on Smad consensus sequences and was partially dependent on endogenous TGF-β signaling and Smad4. Knockdown of PUMA in BL cells using lentiviral shRNA resulted in slower kinetics of the TGF-β-mediated apoptotic response. Analysis of Eμ-Myc cell lines demonstrated that c-myc-driven murine lymphomas are also sensitive to TGF-β-mediated apoptosis. Moreover, Puma(-/-) Eμ-Myc lines demonstrated significantly delayed kinetics of the apoptotic response when compared with wild type lymphomas. TGF-β therefore induces a polygenic response in Myc-driven lymphomas involving transcription of PUMA, which is necessary for the rapid induction of cell death.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins / metabolism*
  • Apoptosis*
  • Cell Line
  • Cell Survival
  • Gene Expression Regulation, Neoplastic*
  • HEK293 Cells
  • Humans
  • Kinetics
  • Lymphoma / metabolism
  • Lymphoma, B-Cell / metabolism*
  • Mice
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Signal Transduction
  • Transcription, Genetic
  • Transforming Growth Factor beta / metabolism*
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Apoptosis Regulatory Proteins
  • BBC3 protein, human
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-myc
  • TP53 protein, human
  • Transforming Growth Factor beta
  • Tumor Suppressor Protein p53