Dataset Information

Poly(ADP-ribose) polymerase 1 (PARP1) overexpression in human breast cancer stem cells and resistance to olaparib.

ABSTRACT:

Background

Breast cancer stem cells (BCSCs) have been recognized as playing a major role in various aspects of breast cancer biology. To identify specific biomarkers of BCSCs, we have performed comparative proteomics of BCSC-enriched and mature cancer cell populations from the human breast cancer cell line (BCL), BrCA-MZ-01.

Methods

ALDEFLUOR assay was used to sort BCSC-enriched (ALDH+) and mature cancer (ALDH-) cell populations. Total proteins were extracted from both fractions and subjected to 2-Dimensional Difference In-Gel Electrophoresis (2-D DIGE). Differentially-expressed spots were excised and proteins were gel-extracted, digested and identified using MALDI-TOF MS.

Results

2-D DIGE identified poly(ADP-ribose) polymerase 1 (PARP1) as overexpressed in ALDH+ cells from BrCA-MZ-01. This observation was confirmed by western blot and extended to four additional human BCLs. ALDH+ cells from BRCA1-mutated HCC1937, which had the highest level of PARP1 overexpression, displayed resistance to olaparib, a specific PARP1 inhibitor.

Conclusion

An unbiased proteomic approach identified PARP1 as upregulated in ALDH+, BCSC-enriched cells from various human BCLs, which may contribute to clinical resistance to PARP inhibitors.

SUBMITTER: Gilabert M

PROVIDER: S-EPMC4140711 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Poly(ADP-ribose) polymerase 1 (PARP1) overexpression in human breast cancer stem cells and resistance to olaparib.

Gilabert Marine M Launay Simon S Ginestier Christophe C Bertucci François F Audebert Stéphane S Pophillat Mathieu M Toiron Yves Y Baudelet Emilie E Finetti Pascal P Noguchi Tetsuro T Sobol Hagay H Birnbaum Daniel D Borg Jean-Paul JP Charafe-Jauffret Emmanuelle E Gonçalves Anthony A

PloS one 20140821 8

<h4>Background</h4>Breast cancer stem cells (BCSCs) have been recognized as playing a major role in various aspects of breast cancer biology. To identify specific biomarkers of BCSCs, we have performed comparative proteomics of BCSC-enriched and mature cancer cell populations from the human breast cancer cell line (BCL), BrCA-MZ-01.<h4>Methods</h4>ALDEFLUOR assay was used to sort BCSC-enriched (ALDH+) and mature cancer (ALDH-) cell populations. Total proteins were extracted from both fractions a ...[more]

PMID: 25144364

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Project description:ObjectiveActivation of the constitutive nuclear and mitochondrial enzyme poly (ADP-ribose) polymerase (PARP) has been implicated in the pathogenesis of cell dysfunction, inflammation, and organ failure in various forms of critical illness. The objective of our study was to evaluate the efficacy and safety of the clinically approved PARP inhibitor olaparib in an experimental model of pancreatitis in vivo and in a pancreatic cell line subjected to oxidative stress in vitro. The preclinical studies were complemented with analysis of clinical samples to detect PARP activation in pancreatitis.MethodsMice were subjected to cerulein-induced pancreatitis; circulating mediators and circulating organ injury markers; pancreatic myeloperoxidase and malondialdehyde levels were measured and histology of the pancreas was assessed. In human pancreatic duct epithelial cells (HPDE) subjected to oxidative stress, PARP activation was measured by PAR Western blotting and cell viability and DNA integrity were quantified. In clinical samples, PARP activation was assessed by PAR (the enzymatic product of PARP) immunohistochemistry.ResultsIn male mice subjected to pancreatitis, olaparib (3 mg/kg i.p.) improved pancreatic function: it reduced pancreatic myeloperoxidase and malondialdehyde levels, attenuated the plasma amylase levels, and improved the histological picture of the pancreas. It also attenuated the plasma levels of pro-inflammatory mediators (TNF-α, IL-1β, IL-2, IL-4, IL-6, IL-12, IP-10, KC) but not MCP-1, RANTES, or the anti-inflammatory cytokine IL-10. Finally, it prevented the slight, but significant increase in plasma blood urea nitrogen level, suggesting improved renal function. The protective effect of olaparib was also confirmed in female mice. In HPDE cells subjected to oxidative stress olaparib (1 μM) inhibited PARP activity, protected against the loss of cell viability, and prevented the loss of cellular NAD levels. Olaparib, at 1μM to 30 μM did not have any adverse effects on DNA integrity. In human pancreatic samples from patients who died of pancreatitis, increased accumulation of PAR was demonstrated.ConclusionOlaparib improves organ function and tempers the hyperinflammatory response in pancreatitis. It also protects against pancreatic cell injury in vitro without adversely affecting DNA integrity. Repurposing and eventual clinical introduction of this clinically approved PARP inhibitor may be warranted for the experimental therapy of pancreatitis.

Project description:Poly (ADP-ribose) polymerase-1 (PARP1) is a key facilitator of DNA repair and is implicated in pathways of tumorigenesis. PARP inhibitors have gained recent attention as rationally designed therapeutics for the treatment of several malignancies, particularly those associated with dysfunctional DNA repair pathways, including triple-negative breast cancer (TNBC). We investigated the PARP1 gene expression profile in surgical samples from more than 8,000 primary malignant and normal human tissues. PARP1 expression was found to be significantly increased in several malignant tissues, including those isolated from patients with breast, uterine, lung, ovarian, and skin cancers, and non-Hodgkin's lymphoma. Within breast infiltrating ductal carcinoma (IDC) samples tested, mean PARP1 expression was significantly higher relative to normal breast tissue, with over 30% of IDC samples demonstrating upregulation of PARP1, compared with 2.9% of normal tissues. Because of known DNA repair defects, including BRCA1 dysfunction, associated with TNBC, exploration of PARP1 expression in breast cancers related to expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) led to the observation that negative expression of any of the 3 receptors was associated with upregulation of PARP1 expression, compared with receptor-positive tissues. To validate these observations, an independent set of breast adenocarcinomas was evaluated and demonstrated >2-fold upregulation of PARP1 in approximately 70% of primary breast adenocarcinomas, including TNBC, compared with syngeneic nonmalignant breast tissues. Immunohistochemistry (IHC) showed that upregulation of the PARP1 gene was consistent with increased protein expression in TNBC. These analyses suggest a potential biological role for PARP1 in several distinct malignancies, including TNBC. Further investigation of PARP1 as a biomarker for the therapeutic activity of PARP inhibitor-based therapy is warranted.

Project description:Poly(ADP-ribose) polymerases (PARPs) are involved in many aspects of the cellular response to various forms of damage. PARP-1 and PARP-2, the most abundant PARPs, are central to the response to specific types of DNA damage, especially single-strand breaks. Inhibition of PARP activity may sensitize the cell to exogenous agents such as chemotherapy and radiation. In circumstances where rescue pathways are deficient, particularly the homologous recombination (HR)-directed DNA repair pathway, inhibition of PARP may result in "synthetic lethality." BRCA mutation-associated breast cancers are a paradigm of HR-directed repair deficient tumors. Early clinical trials have demonstrated significant activity of single-agent PARP inhibitors in BRCA-deficient breast and ovarian cancer. Because of phenotypic similarities between some "triple-negative" breast cancers (TNBC) and the most prevalent type of breast cancer seen in BRCA1 mutation carriers, some have hypothesized that TNBC might also be specifically sensitive to PARP inhibition. The activity of single-agent PARP inhibitors in TNBC has not been reported. One trial did suggest significant enhancement of the activity of platinum-based combination chemotherapy, without incremental toxicity. These studies indicate that PARP inhibition is an exciting new approach to the treatment of breast cancers in women with underlying BRCA mutations and possibly in sporadic cancers with defects in HR-directed repair. Future studies will be necessary to determine whether the effectiveness of PARP inhibitors in nonhereditary cancer requires an underlying HR defect or whether these agents may improve the activity of conventional chemotherapy by other means. In addition, studies will be required to determine whether PARP inhibitors may induce synthetic lethality in tumors with defects in pathways other than the BRCA-dependent DNA repair pathway. If either or both of these prove to be the case, then PARP inhibition may benefit a wide spectrum of cancer patients.

Dataset Information

Poly(ADP-ribose) polymerase 1 (PARP1) overexpression in human breast cancer stem cells and resistance to olaparib.

Background

Methods

Results

Conclusion

Publications

Poly(ADP-ribose) polymerase 1 (PARP1) overexpression in human breast cancer stem cells and resistance to olaparib.

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