Complex Cisplatin-Double Strand Break (DSB) Lesions Directly Impair Cellular Non-Homologous End-Joining (NHEJ) Independent of Downstream Damage Response (DDR) Pathways

Sears, Catherine R.; Turchi, John J.

doi:10.1074/jbc.m112.344911

Cited by 50 publications

(48 citation statements)

References 34 publications

(58 reference statements)

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“…Cisplatin-induced and SAHA-induced radiosensitizations involve distinct compromised DNA damage repair pathways It has been previously reported that cisplatin treatment does not affect NHEJ activity, however, complex cisplatin-DSB lesions directly impair cellular NHEJ (11,21). On the other hand, our studies showed that exposure to SAHA reduced expression of Rad51, a key element involved in HDR pathway, and decreased HDR activity in irradiated cancer cells (14,16).…”

Section: Resultssupporting

confidence: 43%

“…A chemotherapeutic drug may also act as a radiosensitizer and increase the effect of radiation treatment (10). Of note, studies have shown that cisplatin can increase radiosensitization (11). However, studies also revealed that cisplatin treatment is associated with significant toxic effects and requires fluid hydration, which can be problematic in patients with cardiovascular disease.…”

Section: Introductionmentioning

confidence: 99%

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Combined Effects of Suberoylanilide Hydroxamic Acid and Cisplatin on Radiation Sensitivity and Cancer Cell Invasion in Non–Small Cell Lung Cancer

Jiang

Zhang

et al. 2016

Molecular Cancer Therapeutics

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Lung cancer is a leading cause of cancer-related mortality worldwide, and concurrent chemoradiotherapy has been explored as a therapeutic option. However, the chemotherapeutic agents cannot be administered for most patients at full doses safely with radical doses of thoracic radiation, and further optimizations of the chemotherapy regimen to be given with radiation are needed. In this study, we examined the effects of suberoylanilide hydroxamic acid (SAHA) and cisplatin on DNA damage repairs, and determined the combination effects of SAHA and cisplatin on human non-small cell lung cancer (NSCLC) cells in response to treatment of ionizing radiation (IR), and on tumor growth of lung cancer H460 xenografts receiving radiotherapy. We also investigated the potential differentiation effect of SAHA and its consequences on cancer cell invasion. Our results showed that SAHA and cisplatin compromise distinct DNA damage repair pathways, and treatment with SAHA enhanced synergistic radiosensitization effects of cisplatin in established NSCLC cell lines in a p53-independent manner, and decreased the DNA damage repair capability in cisplatin-treated primary NSCLC tumor tissues in response to IR. SAHA combined with cisplatin also significantly increased inhibitory effect of radiotherapy on tumor growth in the mouse xenograft model. In addition, SAHA can induce differentiation in stem cell-like cancer cell population, reduce tumorigenicity, and decrease invasiveness of human lung cancer cells. In conclusion, our data suggest a potential clinical impact for SAHA as a radiosensitizer and as a part of a chemoradiotherapy regimen for NSCLC. Mol Cancer Ther; 15(5); 842-53. Ó2016 AACR.

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Section: Resultssupporting

confidence: 43%

Section: Introductionmentioning

confidence: 99%

Combined Effects of Suberoylanilide Hydroxamic Acid and Cisplatin on Radiation Sensitivity and Cancer Cell Invasion in Non–Small Cell Lung Cancer

Jiang

Zhang

et al. 2016

Molecular Cancer Therapeutics

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“…Conversely, compared to the untreated BUB1 RNAi cells, the number of nuclear foci increased nearly 2-fold following treatment with the DNA cross-linking agent cisplatin, which impairs the cellular NHEJ pathway (51). This elevated 53BP1 focus formation correlated with levels of ␥-H2AX phosphorylation in BUB1-depleted cells (Fig.…”

Section: Resultsmentioning

confidence: 87%

Spindle Checkpoint Factors Bub1 and Bub2 Promote DNA Double-Strand Break Repair by Nonhomologous End Joining

Jessulat

Malty

Nguyen-Tran

et al. 2015

Molecular and Cellular Biology

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The nonhomologous end-joining (NHEJ) pathway is essential for the preservation of genome integrity, as it efficiently repairs DNA double-strand breaks (DSBs). Previous biochemical and genetic investigations have indicated that, despite the importance of this pathway, the entire complement of genes regulating NHEJ remains unknown. To address this, we employed a plasmidbased NHEJ DNA repair screen in budding yeast (Saccharomyces cerevisiae) using 369 putative nonessential DNA repair-related components as queries. Among the newly identified genes associated with NHEJ deficiency upon disruption are two spindle assembly checkpoint kinases, Bub1 and Bub2. Both observation of resulting phenotypes and chromatin immunoprecipitation demonstrated that Bub1 and -2, either alone or in combination with cell cycle regulators, are recruited near the DSB, where phosphorylated Rad53 or H2A accumulates. Large-scale proteomic analysis of Bub kinases phosphorylated in response to DNA damage identified previously unknown kinase substrates on Tel1 S/T-Q sites. Moreover, Bub1 NHEJ function appears to be conserved in mammalian cells. 53BP1, which influences DSB repair by NHEJ, colocalizes with human BUB1 and is recruited to the break sites. Thus, while Bub is not a core component of NHEJ machinery, our data support its dual role in mitotic exit and promotion of NHEJ repair in yeast and mammals.T he repair of DNA double-strand breaks (DSBs) is an essential process required for the preservation of genome integrity and the normal functioning of the cell (1). These cytotoxic lesions are repaired by major DSB repair pathways, including the homologous recombination (HR) (2) and nonhomologous end-joining (NHEJ) systems (1). While the former is the prevalent pathway in the unicellular budding yeast Saccharomyces cerevisiae (3), the latter is more prevalent in mammalian cells, especially those that are quiescent (4), and can repair DNA lesions even if there is no homologous strand (5). Notably, the impairment of NHEJ in mammalian cells is frequently linked to genomic instability, cancer, and lymphoid V(D)J (i.e., variable, diversity, and joining gene segments) recombination defects. Therefore, a detailed molecular understanding of this pathway would provide critical insight into the genetic risk factors related to carcinogenesis or immunological disorders (6).As in mammalian cells, the core components of the classical NHEJ pathway in S. cerevisiae depends on three major complexes, YKu (Ku), MRX, and DNL4, which are rapidly recruited to DSBs (7). Initially, the yeast Ku heterodimer (Ku70/80) binds to each end of a DSB, serving as an anchor for protein complexes involved in securing and annealing the break, also suppressing the competing HR pathway (8). After this, the DSB processing complex MRX (Mre11-Rad50-Xrs2), which acts at an early stage of both the NHEJ and HR repair pathways (9), spans the lesions so that the DNA ligase complex, DNL4 (i.e., Dnl4-Lif1-Nej1), can rejoin the DSB ends (10).While the actions of these core protein complexes in y...

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“…9,17,28,29 The presence of a CDDP lesion on DNA inhibits NHEJ 17,30,31 and we hypothesize that CDDP-IR synergy is determined by a CDDP lesion at close proximity to a DSB. However, despite the recognition of a likely role for DNA repair pathways in CDDP radiosensitization, little is known about the actual mechanism and role of the DDR in radiosensitization.…”

Section: Introductionmentioning

confidence: 89%

DNA damage response (DDR) pathway engagement in cisplatin radiosensitization of non-small cell lung cancer

et al. 2016

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Non-small cell lung cancers (NSCLC) are commonly treated with a platinum-based chemotherapy such as cisplatin (CDDP) in combination with ionizing radiation (IR). Although clinical trials have demonstrated that the combination of CDDP and IR appear to be synergistic in terms of therapeutic efficacy, the mechanism of synergism remains largely uncharacterized. We investigated the role of the DNA damage response (DDR) in CDDP radiosensitization using two NSCLC cell lines. Using clonogenic survival assays, we determined that the cooperative cytotoxicity of CDDP and IR treatment is sequence dependent, requiring administration of CDDP prior to IR (CDDP-IR). We identified and interrogated the unique time and agent-dependent activation of the DDR in NSCLC cells treated with cisplatin-IR combination therapy. Compared to treatment with CDDP or IR alone, CDDP-IR combination treatment led to persistence of γH2Ax foci, a marker of DNA double-strand breaks (DSB), for up to 24 hours after treatment. Interestingly, pharmacologic inhibition of DDR sensor kinases revealed the persistence of γ-H2Ax foci in CDDP-IR treated cells is independent of kinase activation. Taken together, our data suggest that delayed repair of DSBs in NSCLC cells treated with CDDP-IR contributes to CDDP radiosensitization and that alterations of the DDR pathways by inhibition of specific DDR kinases can augment CDDP-IR cytotoxicity by a complementary mechanism.

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Complex Cisplatin-Double Strand Break (DSB) Lesions Directly Impair Cellular Non-Homologous End-Joining (NHEJ) Independent of Downstream Damage Response (DDR) Pathways

Cited by 50 publications

References 34 publications

Combined Effects of Suberoylanilide Hydroxamic Acid and Cisplatin on Radiation Sensitivity and Cancer Cell Invasion in Non–Small Cell Lung Cancer

Combined Effects of Suberoylanilide Hydroxamic Acid and Cisplatin on Radiation Sensitivity and Cancer Cell Invasion in Non–Small Cell Lung Cancer

Spindle Checkpoint Factors Bub1 and Bub2 Promote DNA Double-Strand Break Repair by Nonhomologous End Joining

DNA damage response (DDR) pathway engagement in cisplatin radiosensitization of non-small cell lung cancer

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