EGR-1 forms a complex with YAP-1 and upregulates Bax expression in irradiated prostate carcinoma cells

Oncogene. 2009 Feb 26;28(8):1121-31. doi: 10.1038/onc.2008.461. Epub 2009 Jan 12.

Abstract

In this study, we investigated the functional role of early growth response-1 (Egr1 gene) in the regulation of radiation-induced clonogenic inhibition and apoptosis in p53 wild-type and mutant prostate cancer cells 22Rv1 and DU145, respectively. 22Rv1 cells were more sensitive to irradiation compared with DU145 cells, and the sensitivity was enhanced by overexpression of EGR-1 in both cells. Dominant-negative EGR-1 mutant (dnEGR-1) or repressor of EGR-1, NGFIA binding protein 1 (NAB1), increased radioresistance of these cells. Significant activation of caspases 3 and 9 and Bcl2-associated X (Bax) with increased poly(ADP-ribose) polymerase (PARP) cleavage and cytochrome c release was observed in radiation-exposed EGR-1 overexpressing cells. Gel shift analysis and chloramphenicol acetyl transferase (CAT) reporter assays indicate that EGR-1 transactivates the promoter of the Bax gene. Interaction of EGR-1 and Yes kinase-associated protein 1 (YAP-1) through the WW domain of YAP-1 enhances the transcriptional activity of EGR-1 on the Bax promoter as shown by chromatin immunoprecipitation and reporter assays. Irradiation of PC3 cell xenografts that were treated with adenoviral EGR-1 showed significant regression in tumor volume. These findings establish the radiation-induced pro-apoptotic action of EGR-1, in a p53-independent manner, by directly transactivating Bax, and prove that alters the B-cell CLL/lymphoma 2 (Bcl-2)/Bax ratio as one of the mechanisms resulting in significant activation of caspases, leading to cell death through the novel interaction of EGR-1 with YAP-1.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apoptosis / physiology
  • Apoptosis / radiation effects*
  • Blotting, Western
  • Caspase 3 / metabolism
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Colony-Forming Units Assay
  • Cytochromes c / metabolism
  • Early Growth Response Protein 1 / genetics
  • Early Growth Response Protein 1 / metabolism*
  • Electrophoretic Mobility Shift Assay
  • Humans
  • Immunoprecipitation
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Poly(ADP-ribose) Polymerases / metabolism
  • Promoter Regions, Genetic
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism*
  • Prostatic Neoplasms / pathology*
  • Protein Array Analysis
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Radiation Tolerance
  • Repressor Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors
  • Transcriptional Activation
  • Transfection
  • Transplantation, Heterologous
  • Tumor Cells, Cultured
  • Up-Regulation
  • X-Rays
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • BAX protein, human
  • EGR1 protein, human
  • Early Growth Response Protein 1
  • NAB1 protein, human
  • Phosphoproteins
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • Repressor Proteins
  • Transcription Factors
  • YAP1 protein, human
  • bcl-2-Associated X Protein
  • Cytochromes c
  • Chloramphenicol O-Acetyltransferase
  • Poly(ADP-ribose) Polymerases
  • Caspase 3