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

Pessetto, Ziyan Y.; Yan, Ying; Bessho, Tadayoshi; Natarajan, Amarnath

doi:10.1007/s10549-012-2079-4

Cited by 36 publications

(35 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In TNBC patients that are not BRCA-1 defective, agents that lead to BRCA-1 inhibition combined with targeted alpha radiotherapy would be useful. Until recently, only a handful of BRCA-1 inhibitors, however, are under early stage evaluation primarily due to low specificity since many of these protein-protein interactions, unlike enzyme active sites, also have large, multiple contact points and poorly defined topology (48). Many other DSB repair inhibitors are currently available for combination with targeted alpha therapy for TNBC including the DNA-PKcs inhibitor used in this study (29), Ataxia-Telangiectasia Mutated Kinase (ATM) inhibitor and Rad51 inhibitors (49).…”

Section: Discussionmentioning

confidence: 99%

Targeting Aberrant DNA Double-Strand Break Repair in Triple-Negative Breast Cancer with Alpha-Particle Emitter Radiolabeled Anti-EGFR Antibody

Song

Hedayati²,

Hobbs

et al. 2013

Molecular Cancer Therapeutics

View full text Add to dashboard Cite

The higher potential efficacy of alpha-particle radiopharmaceutical therapy lies in the 3 to 8-fold greater biological effectiveness (RBE) of alpha particles relative to photon or beta-particle radiation. This greater RBE, however, also applies to normal tissue, thereby reducing the potential advantage of high RBE. Since alpha particles typically cause DNA double strand breaks (DSBs), targeting tumors that are defective in DSB repair effectively increases the RBE, yielding a secondary, RBE-based differentiation between tumor and normal tissue that is complementary to conventional, receptor-mediated tumor targeting. In some triple negative breast cancers (TNBC, ER−/PR−/HER-2−), germline mutation in BRCA-1, a key gene in homologous recombination (HR) DSB repair, predisposes patients to early onset of breast cancer. These patients have few treatment options once the cancer has metastasized. In this study, we investigated the efficacy of alpha particle emitter, 213Bi labeled anti-EGFR antibody, Cetuximab, in BRCA-1 defective TNBC. 213Bi-Cetuximab was found to be significantly more effective in the BRCA-1 mutated TNBC cell line HCC1937 than BRCA-1 competent TNBC cell MDA-MB-231. siRNA knockdown of BRCA-1 or DNA-PKcs, a key gene in non-homologous end joining (NHEJ) DSB repair pathway, also sensitized TNBC cells to 213Bi-Cetuximab. Furthermore, the small molecule inhibitor of DNA-PKcs, NU7441, sensitized BRCA-1 competent TNBC cells to alpha particle radiation. Immunofluorescent staining of γH2AX foci and comet assay confirmed that enhanced RBE is caused by impaired DSB repair. These data offer a novel strategy for enhancing conventional receptor-mediated targeting with an additional, potentially synergistic radiobiological targeting that could be applied to TNBC.

show abstract

Section: Discussionmentioning

confidence: 99%

Targeting Aberrant DNA Double-Strand Break Repair in Triple-Negative Breast Cancer with Alpha-Particle Emitter Radiolabeled Anti-EGFR Antibody

Song

Hedayati²,

Hobbs

et al. 2013

Molecular Cancer Therapeutics

View full text Add to dashboard Cite

show abstract

“…( e ) The indicated cells were analyzed for growth kinetics using AlamarBlue assay, as described previously. 59 At indicated time points, 10% of AlamarBlue reagent was added to the cells, incubated for 130 min and measured for fluorescence intensity using a SpectraMax M5 plate reader (Molecular Devices, Inc.) at ex/em 544/590 nm.…”

Section: Figurementioning

confidence: 99%

RAC1 GTPase promotes the survival of breast cancer cells in response to hyper-fractionated radiation treatment

et al. 2016

View full text Add to dashboard Cite

Radiation therapy is a staple approach for cancer treatment, whereas radioresistance of cancer cells remains a substantial clinical problem. In response to ionizing radiation (IR) induced DNA-damage, cancer cells can sustain/activate pro-survival signaling pathways, leading to apoptotic resistance and induction of cell cycle checkpoint/DNA repair. Previous studies show that Rac1 GTPase is overexpressed/hyperactivated in breast cancer cells and is associated with poor prognosis. Studies from our laboratory reveal that Rac1 activity is necessary for G2/M checkpoint activation and cell survival in response to IR exposure of breast and pancreatic cancer cells. In the present study, we investigated the effect of Rac1 on the survival of breast cancer cells treated with hyper-fractionated radiation (HFR), which is used clinically for cancer treatment. Results in this report indicate that Rac1 protein expression is increased in the breast cancer cells that survived HFR compared to parental cells. Furthermore, this increase of Rac1 is associated with enhanced activities of ERK1/2 and NF-κB signaling pathways and increased levels of anti-apoptotic protein Bcl-xL and Mcl-1, which are downstream targets of ERK1/2 and NF-κB signaling pathways. Using Rac1 specific inhibitor and dominant negative mutant N17Rac1, here we demonstrate that Rac1 inhibition decreases the phosphorylation of ERK1/2 and IκBα, as well as the levels of Bcl-xL and Mcl-1 protein in the HFR-selected breast cancer cells. Moreover, inhibition of Rac1 using either small molecule inhibitor or dominant negative N17Rac1 abrogates clonogenic survival of HFR-selected breast cancer cells and decreases the level of intact PARP, which is indicative of apoptosis induction. Collectively, results in this report suggest that Rac1 signaling is essential for the survival of breast cancer cells subjected to HFR and implicate Rac1 in radioresistance of breast cancer cells. These studies also provide the basis to explore Rac1 as a therapeutic target for radioresistant breast cancer cells.

show abstract

“…Recently, cell studies have been conducted with a phosphorylated BRCA1 peptide inhibitor attached to a cell penetrating peptide 53 and with a difluorophosphonate-containing BRCA1 inhibitor. 21 Addition of these molecules at high concentrations to cells led to several phenotypes associated with BRCA1 deficiency.…”

Section: Resultsmentioning

confidence: 99%

Peptide Library Approach to Uncover Phosphomimetic Inhibitors of the BRCA1 C-Terminal Domain

White

Sun

Ma³

et al. 2015

ACS Chem. Biol.

View full text Add to dashboard Cite

Many intracellular protein–protein interactions are mediated by the phosphorylation of serine, and phosphoserine-containing peptides can inhibit these interactions. However, hydrolysis of the phosphate by phosphatases, and the poor cell permeability associated with phosphorylated peptides has limited their utility in cellular and in vivo contexts. Compounding the problem, strategies to replace phosphoserine in peptide inhibitors with easily accessible mimetics (such as Glu or Asp) routinely fail. Here, we present an in vitro selection strategy for replacement of phosphoserine. Using mRNA display, we created a 10 trillion member structurally diverse unnatural peptide library. From this library, we found a peptide that specifically binds to the C-terminal domain (BRCT)2 of breast cancer associated protein 1 (BRCA1) with an affinity comparable to phosphorylated peptides. A crystal structure of the peptide bound reveals that the pSer-x-x-Phe motif normally found in BRCA1 (BRCT)2 binding partners is replaced by a Glu-x-x-4-fluoroPhe and that the peptide picks up additional contacts on the protein surface not observed in cognate phosphopeptide binding. Expression of the peptide in human cells led to defects in DNA repair by homologous recombination, a process BRCA1 is known to coordinate. Overall, this work validates a new in vitro selection approach for the development of inhibitors of protein–protein interactions mediated by serine phosphorylation.

show abstract

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

Cited by 36 publications

References 24 publications

Targeting Aberrant DNA Double-Strand Break Repair in Triple-Negative Breast Cancer with Alpha-Particle Emitter Radiolabeled Anti-EGFR Antibody

Targeting Aberrant DNA Double-Strand Break Repair in Triple-Negative Breast Cancer with Alpha-Particle Emitter Radiolabeled Anti-EGFR Antibody

RAC1 GTPase promotes the survival of breast cancer cells in response to hyper-fractionated radiation treatment

Peptide Library Approach to Uncover Phosphomimetic Inhibitors of the BRCA1 C-Terminal Domain

Contact Info

Product

Resources

About