Inhibition of BRCT(BRCA1)-phosphoprotein interaction enhances the cytotoxic effect of olaparib in breast cancer cells: A proof of concept study for synthetic lethal therapeutic option

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Abstract

Synthetic lethal therapeutic strategy using poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor olaparib in carriers of BRCA1 or BRCA2 mutation has shown promise in clinical settings. Since ≤5 % of patients are BRCA1 or BRCA2 mutation carriers, small molecules that functionally mimic BRCA1 or BRCA2 mutations will extend the synthetic lethal therapeutic option for non-mutation carriers. Here we provide proof of principle for this strategy using a BRCA1 inhibitor peptide 2 that targets the BRCT(BRCA1)-phosphoprotein interaction and mimics the M177R/K BRCA1 mutation. Reciprocal immunoprecipitation and immunoblotting of BRCA1 and Abraxas was used to demonstrate inhibitor 2 targets BRCT(BRCA1)-Abraxas interface. Immunostaining of γH2AX, cell cycle analysis and homologous recombination (HR) assays were conducted to confirm that inhibitor 2 functionally mimics a chemosensitizing BRCA1 mutation. The concept of synthetic lethal therapeutic strategy with the BRCA1 inhibitor 2 and the PARP inhibitor Olaparib was explored in HeLa, MDA-MB-231, and HCC1937 cell lines. The results show that inhibition of BRCA1 by 2 sensitizes HeLa and MDA-MB-231 cells but not HCC1937 to Olaparib mediated growth inhibition and apoptosis. These results provide the basis for developing high affinity BRCT(BRCA1) inhibitors as adjuvants to treat sporadic breast and ovarian cancers. Â

Original languageEnglish (US)
Pages (from-to)511-517
Number of pages7
JournalBreast Cancer Research and Treatment
Volume134
Issue number2
DOIs
StatePublished - Jul 2012

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Phosphoproteins
Breast Neoplasms
Mutation
Poly Adenosine Diphosphate Ribose
Therapeutics
Homologous Recombination
Immunoprecipitation
Immunoblotting
Ovarian Neoplasms
Cell Cycle
olaparib
Apoptosis
Cell Line
Peptides
Growth
Poly(ADP-ribose) Polymerase Inhibitors

Keywords

  • Abraxas
  • BRCA1 inhibitor
  • Chemosensitization
  • Olaparib and IR
  • Synthetic lethal therapeutic strategy

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

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title = "Inhibition of BRCT(BRCA1)-phosphoprotein interaction enhances the cytotoxic effect of olaparib in breast cancer cells: A proof of concept study for synthetic lethal therapeutic option",
abstract = "Synthetic lethal therapeutic strategy using poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor olaparib in carriers of BRCA1 or BRCA2 mutation has shown promise in clinical settings. Since {\^a}‰¤5 {\%} of patients are BRCA1 or BRCA2 mutation carriers, small molecules that functionally mimic BRCA1 or BRCA2 mutations will extend the synthetic lethal therapeutic option for non-mutation carriers. Here we provide proof of principle for this strategy using a BRCA1 inhibitor peptide 2 that targets the BRCT(BRCA1)-phosphoprotein interaction and mimics the M177R/K BRCA1 mutation. Reciprocal immunoprecipitation and immunoblotting of BRCA1 and Abraxas was used to demonstrate inhibitor 2 targets BRCT(BRCA1)-Abraxas interface. Immunostaining of {\^I}³H2AX, cell cycle analysis and homologous recombination (HR) assays were conducted to confirm that inhibitor 2 functionally mimics a chemosensitizing BRCA1 mutation. The concept of synthetic lethal therapeutic strategy with the BRCA1 inhibitor 2 and the PARP inhibitor Olaparib was explored in HeLa, MDA-MB-231, and HCC1937 cell lines. The results show that inhibition of BRCA1 by 2 sensitizes HeLa and MDA-MB-231 cells but not HCC1937 to Olaparib mediated growth inhibition and apoptosis. These results provide the basis for developing high affinity BRCT(BRCA1) inhibitors as adjuvants to treat sporadic breast and ovarian cancers. {\^A}",
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author = "Pessetto, {Ziyan Yuan} and Ying Yan and Tadayoshi Bessho and Amarnath Natarajan",
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T1 - Inhibition of BRCT(BRCA1)-phosphoprotein interaction enhances the cytotoxic effect of olaparib in breast cancer cells

T2 - A proof of concept study for synthetic lethal therapeutic option

AU - Pessetto, Ziyan Yuan

AU - Yan, Ying

AU - Bessho, Tadayoshi

AU - Natarajan, Amarnath

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N2 - Synthetic lethal therapeutic strategy using poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor olaparib in carriers of BRCA1 or BRCA2 mutation has shown promise in clinical settings. Since ≤5 % of patients are BRCA1 or BRCA2 mutation carriers, small molecules that functionally mimic BRCA1 or BRCA2 mutations will extend the synthetic lethal therapeutic option for non-mutation carriers. Here we provide proof of principle for this strategy using a BRCA1 inhibitor peptide 2 that targets the BRCT(BRCA1)-phosphoprotein interaction and mimics the M177R/K BRCA1 mutation. Reciprocal immunoprecipitation and immunoblotting of BRCA1 and Abraxas was used to demonstrate inhibitor 2 targets BRCT(BRCA1)-Abraxas interface. Immunostaining of γH2AX, cell cycle analysis and homologous recombination (HR) assays were conducted to confirm that inhibitor 2 functionally mimics a chemosensitizing BRCA1 mutation. The concept of synthetic lethal therapeutic strategy with the BRCA1 inhibitor 2 and the PARP inhibitor Olaparib was explored in HeLa, MDA-MB-231, and HCC1937 cell lines. The results show that inhibition of BRCA1 by 2 sensitizes HeLa and MDA-MB-231 cells but not HCC1937 to Olaparib mediated growth inhibition and apoptosis. These results provide the basis for developing high affinity BRCT(BRCA1) inhibitors as adjuvants to treat sporadic breast and ovarian cancers. Â

AB - Synthetic lethal therapeutic strategy using poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor olaparib in carriers of BRCA1 or BRCA2 mutation has shown promise in clinical settings. Since ≤5 % of patients are BRCA1 or BRCA2 mutation carriers, small molecules that functionally mimic BRCA1 or BRCA2 mutations will extend the synthetic lethal therapeutic option for non-mutation carriers. Here we provide proof of principle for this strategy using a BRCA1 inhibitor peptide 2 that targets the BRCT(BRCA1)-phosphoprotein interaction and mimics the M177R/K BRCA1 mutation. Reciprocal immunoprecipitation and immunoblotting of BRCA1 and Abraxas was used to demonstrate inhibitor 2 targets BRCT(BRCA1)-Abraxas interface. Immunostaining of γH2AX, cell cycle analysis and homologous recombination (HR) assays were conducted to confirm that inhibitor 2 functionally mimics a chemosensitizing BRCA1 mutation. The concept of synthetic lethal therapeutic strategy with the BRCA1 inhibitor 2 and the PARP inhibitor Olaparib was explored in HeLa, MDA-MB-231, and HCC1937 cell lines. The results show that inhibition of BRCA1 by 2 sensitizes HeLa and MDA-MB-231 cells but not HCC1937 to Olaparib mediated growth inhibition and apoptosis. These results provide the basis for developing high affinity BRCT(BRCA1) inhibitors as adjuvants to treat sporadic breast and ovarian cancers. Â

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