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Originally published In Press as doi:10.1074/jbc.M511138200 on March 17, 2006
Originally published In Press as doi:10.1074/jbc.M511138200 on February 20, 2006
J. Biol. Chem., Vol. 281, Issue 17, 11496-11505, April 28, 2006
In Prostate Cancer Cells the Interaction of C/EBP with Ku70, Ku80, and Poly(ADP-ribose) Polymerase-1 Increases Sensitivity to DNA Damage*
Hong Yin1 and
Jonathan Glass
From the
Feist-Weiller Cancer Center and Department of Medicine, Health Sciences Center, Shreveport, Louisiana 71130-3932
Prostate cancer cell lines were examined for proteins that partnered with the transcription factor C/EBP by use of a pull-down assay with S-tagged C/EBP combined with matrix-assisted laser desorption ionization time-of-flight mass spectroscopy analysis. Ku70, Ku80, and poly(ADP-ribose) polymerase-1 (PARP-1) were identified as proteins that associated with C/EBP . The physical interaction of C/EBP with these partner proteins was further demonstrated by glutathione S-transferase (GST) pull-downs using purified protein expressed in Escherichia coli. The strongest binding was between C/EBP and PARP-1. Immunoprecipitation of C/EBP expressed in prostate cancer cells co-precipitated Ku70, Ku80, and PARP-1. Deletion analysis of C/EBP indicated that the C terminus of C/EBP was essential for the interaction of C/EBP with Ku70, Ku80, and PARP-1. Functional analysis of the interaction between C/EBP and the Ku proteins as well as PARP-1 showed that cells exhibiting these interactions had increased radiation sensitivity and decreased ability to repair double strand DNA breaks. Deficient DNA repair was dependent on the prostate cancer cell line tested, suggesting a complex process. We conclude that the association of C/EBP with Ku proteins and PARP-1 raises the likelihood that C/EBP -expressing prostate cancer cells may be more sensitive to DNA-damaging agents and may be important in the design of new prostate cancer therapies.
Received for publication, October 13, 2005
, and in revised form, January 26, 2006.
* The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 To whom correspondence should be addressed: Section of Hematology/Oncology Dept. of Medicine, LSU Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932. Tel.: 318-675-4967; Fax: 318-675-4969; E-mail: hyin{at}lsuhsc.edu.

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Copyright © 2006 by the American Society for Biochemistry and Molecular Biology.
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