Dataset Information

Prostate cancer radiosensitization through poly(ADP-Ribose) polymerase-1 hyperactivation.

ABSTRACT: The clinical experimental agent, ?-lapachone (?-lap; Arq 501), can act as a potent radiosensitizer in vitro through an unknown mechanism. In this study, we analyzed the mechanism to determine whether ?-lap may warrant clinical evaluation as a radiosensitizer. ?-Lap killed prostate cancer cells by NAD(P)H:quinone oxidoreductase 1 (NQO1) metabolic bioactivation, triggering a massive induction of reactive oxygen species, irreversible DNA single-strand breaks (SSB), poly(ADP-ribose) polymerase-1 (PARP-1) hyperactivation, NAD(+)/ATP depletion, and ?-calpain-induced programmed necrosis. In combination with ionizing radiation (IR), ?-lap radiosensitized NQO1(+) prostate cancer cells under conditions where nontoxic doses of either agent alone achieved threshold levels of SSBs required for hyperactivation of PARP-1. Combination therapy significantly elevated SSB level, ?-H2AX foci formation, and poly(ADP-ribosylation) of PARP-1, which were associated with ATP loss and induction of ?-calpain-induced programmed cell death. Radiosensitization by ?-lap was blocked by the NQO1 inhibitor dicoumarol or the PARP-1 inhibitor DPQ. In a mouse xenograft model of prostate cancer, ?-lap synergized with IR to promote antitumor efficacy. NQO1 levels were elevated in ?60% of human prostate tumors evaluated relative to adjacent normal tissue, where ?-lap might be efficacious alone or in combination with radiation. Our findings offer a rationale for the clinical utilization of ?-lap (Arq 501) as a radiosensitizer in prostate cancers that overexpress NQO1, offering a potentially synergistic targeting strategy to exploit PARP-1 hyperactivation.

SUBMITTER: Dong Y

PROVIDER: S-EPMC2955807 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Prostate cancer radiosensitization through poly(ADP-Ribose) polymerase-1 hyperactivation.

Dong Ying Y Bey Erik A EA Li Long-Shan LS Kabbani Wareef W Yan Jingsheng J Xie Xian-Jin XJ Hsieh Jer-Tsong JT Gao Jinming J Boothman David A DA

Cancer research 20101012 20

The clinical experimental agent, β-lapachone (β-lap; Arq 501), can act as a potent radiosensitizer in vitro through an unknown mechanism. In this study, we analyzed the mechanism to determine whether β-lap may warrant clinical evaluation as a radiosensitizer. β-Lap killed prostate cancer cells by NAD(P)H:quinone oxidoreductase 1 (NQO1) metabolic bioactivation, triggering a massive induction of reactive oxygen species, irreversible DNA single-strand breaks (SSB), poly(ADP-ribose) polymerase-1 (PA ...[more]

PMID: 20940411

Similar Datasets

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.

Project description:BackgroundDespite standard treatment for epithelial ovarian cancer (EOC), that involves cytoreductive surgery followed by platinum-based chemotherapy, and initial high response rates to these, up to 80 % of patients experience relapses with a median progression-free survival of 12-18 months. There remains an urgent need for novel targeted therapies to improve clinical outcomes in ovarian cancer. Of the many targeted therapies currently under evaluation, the most promising strategies developed thus far are antiangiogenic agents and Poly(ADP-ribose) polymerase (PARP) inhibitors. Particularly, PARP inhibitors are active in cells that have impaired repair of DNA by the homologous recombination (HR) pathway. Cells with mutated breast related cancer antigens (BRCA) function have HR deficiency, which is also present in a significant proportion of non-BRCA-mutated ovarian cancer ("BRCAness" ovarian cancer). The prevalence of germline BRCA mutations in EOC has historically been estimated to be around 10-15 %. However, recent reports suggest that this may be a gross underestimate, especially in women with high-grade serous ovarian cancer (HGSOC). The emergence of the DNA repair pathway as a rational target in various cancers led to the development of the PARP inhibitors. The concept of tumor-selective synthetic lethality heralded the beginning of an eventful decade, culminating in the approval by regulatory authorities both in Europe as a maintenance therapy and in the United States treatment for advanced recurrent disease of the first oral PARP inhibitor, olaparib, for the treatment of BRCA-mutated ovarian cancer patients. Other PARP inhibitors are clearly effective in this disease and, within the next years, the results of ongoing randomized trials will clarify their respective roles.ConclusionThis review will discuss the different PARP inhibitors in development and the potential use of this class of agents in the future. Moreover, combination strategies involving PARP inhibitors are likely to receive increasing attention. The utility of PARP inhibitors combined with cytotoxic chemotherapy is of doubtful value, because of enhanced toxicity of this combination; while, more promising strategies include the combination with antiangiogenic agents, or with inhibitors of the P13K/AKT pathway and new generation of immunotherapy.

Dataset Information

Prostate cancer radiosensitization through poly(ADP-Ribose) polymerase-1 hyperactivation.

Publications

Prostate cancer radiosensitization through poly(ADP-Ribose) polymerase-1 hyperactivation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets