Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells

Hong Lin Devlin, Philip Mack, Rebekah A. Burich, Paul H. Gumerlock, Hsing-Jien Kung, Maria Mudryj, Ralph W deVere White

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Abstract

p53R2 is a p53-inducible ribonucleotide reductase that contributes to DNA repair by supplying deoxynucleotide triphosphate pools in response to DNA damage. In this study, we found that p53R2 was overexpressed in prostate tumor cell lines compared with immortalized prostatic epithelial cells and that the protein was induced upon DNA damage. We investigated the effects of p53R2 silencing on DNA damage in LNCaP cells (wild-type p53). Silencing p53R2 potentiated the apoptotic effects of ionizing radiation and doxorubicin treatment as shown by increased sub-G1 content and decreased colony formation. This sensitizing effect was specific to DNA-damaging agents. Comet assay and γ-H2AX phosphorylation status showed that the decreased p53R2 levels inhibited DNA repair. Silencing p53R2 also reduced the levels of p21 WAF1/CIP1 at the posttranscriptional level, suggesting links between the p53-dependent DNA repair and cell cycle arrest pathways. Using LNCaP sublines stably expressing dominant-negative mutant p53, we found that the sensitizing effect of p53R2 silencing is mediated by p53-dependent apoptosis pathways. In the LNCaP sublines (R273H, R248W, and G245S) that have defects in inducing p53-dependent apoptosis, p53R2 silencing did not potentiate DNA damage-induced apoptosis, whereas p53R2 silencing was effective in a LNCaP subline (P151S) which retains the ability to induce p53-dependent apoptosis. This study shows that p53R2 is a potential therapeutic target that could be used to enhance the effectiveness of ionizing radiation or DNA-damaging chemotherapy in a subset of patients with prostate cancer.

Original languageEnglish (US)
Pages (from-to)808-818
Number of pages11
JournalMolecular Cancer Research
Volume6
Issue number5
DOIs
StatePublished - May 1 2008

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DNA Repair
DNA Damage
Prostatic Neoplasms
Apoptosis
Growth
Ionizing Radiation
Ribonucleotide Reductases
Comet Assay
DNA
Cell Cycle Checkpoints
Tumor Cell Line
Doxorubicin
Prostate
Epithelial Cells
Phosphorylation
Drug Therapy
Therapeutics
Proteins

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Oncology

Cite this

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title = "Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells",
abstract = "p53R2 is a p53-inducible ribonucleotide reductase that contributes to DNA repair by supplying deoxynucleotide triphosphate pools in response to DNA damage. In this study, we found that p53R2 was overexpressed in prostate tumor cell lines compared with immortalized prostatic epithelial cells and that the protein was induced upon DNA damage. We investigated the effects of p53R2 silencing on DNA damage in LNCaP cells (wild-type p53). Silencing p53R2 potentiated the apoptotic effects of ionizing radiation and doxorubicin treatment as shown by increased sub-G1 content and decreased colony formation. This sensitizing effect was specific to DNA-damaging agents. Comet assay and γ-H2AX phosphorylation status showed that the decreased p53R2 levels inhibited DNA repair. Silencing p53R2 also reduced the levels of p21 WAF1/CIP1 at the posttranscriptional level, suggesting links between the p53-dependent DNA repair and cell cycle arrest pathways. Using LNCaP sublines stably expressing dominant-negative mutant p53, we found that the sensitizing effect of p53R2 silencing is mediated by p53-dependent apoptosis pathways. In the LNCaP sublines (R273H, R248W, and G245S) that have defects in inducing p53-dependent apoptosis, p53R2 silencing did not potentiate DNA damage-induced apoptosis, whereas p53R2 silencing was effective in a LNCaP subline (P151S) which retains the ability to induce p53-dependent apoptosis. This study shows that p53R2 is a potential therapeutic target that could be used to enhance the effectiveness of ionizing radiation or DNA-damaging chemotherapy in a subset of patients with prostate cancer.",
author = "Devlin, {Hong Lin} and Philip Mack and Burich, {Rebekah A.} and Gumerlock, {Paul H.} and Hsing-Jien Kung and Maria Mudryj and {deVere White}, {Ralph W}",
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T1 - Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells

AU - Devlin, Hong Lin

AU - Mack, Philip

AU - Burich, Rebekah A.

AU - Gumerlock, Paul H.

AU - Kung, Hsing-Jien

AU - Mudryj, Maria

AU - deVere White, Ralph W

PY - 2008/5/1

Y1 - 2008/5/1

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