The Novel Ribonucleotide Reductase Inhibitor COH29 Inhibits DNA Repair In Vitro

Chen, Mei Chuan; Zhou, Bingsen; Zhang, Keqiang; Yuan, Yate Ching; Un, Frank; Hu, Shuya; Chou, Chih Ming; Chen, Chun Han; Wu, Jun; Wang, Yan; Liu, Xiyong; Smith, D. Lynne; Hong, Frank D.; Liu, Zheng; Warden, Charles; Su, Leila; Malkas, Linda H.; Chung, Young-Min; Hu, Mickey C.T.; Yen, Yun

doi:10.1124/mol.114.094987

Cited by 22 publications

(26 citation statements)

References 35 publications

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“…We then used a virtual screen consisting of docking of 260,721 NCI deposited small molecules to these sites to identify DNA2 inhibitors. This screen is similar to a previous virtual screen used to identify inhibitors of ribonucleotide reductase ( Chen et al, 2015 , Zhou et al, 2013 ). We characterized one inhibitor, C5, which we demonstrate biochemically inhibits nuclease, DNA dependent ATPase, helicase, and DNA binding activities of DNA2.…”

Section: Discussionmentioning

confidence: 92%

A Selective Small Molecule DNA2 Inhibitor for Sensitization of Human Cancer Cells to Chemotherapy

Liu

Zhou

et al. 2016

EBioMedicine

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Cancer cells frequently up-regulate DNA replication and repair proteins such as the multifunctional DNA2 nuclease/helicase, counteracting DNA damage due to replication stress and promoting survival. Therefore, we hypothesized that blocking both DNA replication and repair by inhibiting the bifunctional DNA2 could be a potent strategy to sensitize cancer cells to stresses from radiation or chemotherapeutic agents. We show that homozygous deletion of DNA2 sensitizes cells to ionizing radiation and camptothecin (CPT). Using a virtual high throughput screen, we identify 4-hydroxy-8-nitroquinoline-3-carboxylic acid (C5) as an effective and selective inhibitor of DNA2. Mutagenesis and biochemical analysis define the C5 binding pocket at a DNA-binding motif that is shared by the nuclease and helicase activities, consistent with structural studies that suggest that DNA binding to the helicase domain is necessary for nuclease activity. C5 targets the known functions of DNA2 in vivo: C5 inhibits resection at stalled forks as well as reducing recombination. C5 is an even more potent inhibitor of restart of stalled DNA replication forks and over-resection of nascent DNA in cells defective in replication fork protection, including BRCA2 and BOD1L. C5 sensitizes cells to CPT and synergizes with PARP inhibitors.

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Section: Discussionmentioning

confidence: 92%

A Selective Small Molecule DNA2 Inhibitor for Sensitization of Human Cancer Cells to Chemotherapy

Liu

Zhou

et al. 2016

EBioMedicine

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“…RR inhibitors, first introduced into clinic near 60 years ago, are widely used in cancer therapy. The use of RR inhibitors as anti-cancer agents has been reviewed by Shao and colleagues [ 11 , 41 ]. Because rapidly dividing tumor cells have an increased need for dNTPs, they are far more sensitive to the cytotoxic effects of RR inhibition than normal cells.…”

Section: Discussionmentioning

confidence: 99%

Autophagy induction causes a synthetic lethal sensitization to ribonucleotide reductase inhibition in breast cancer cells

Chen

Tsou

et al. 2015

Oncotarget

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Macroautophagy can promote cellular survival or death depending on the cellular context and its extent. We hypothesized that autophagy induction would synergize with a therapeutic agent targeting the autophagic cargo. To test this hypothesis, we treated breast cancer MDA-MB-231 cells with tamoxifen (TMX), which induces autophagy through an estrogen receptor-independent pathway. Induction of autophagy reduced cellular levels of RRM2, a subunit of ribonucleotide reductase (RR), the rate limiting enzyme in the production of deoxyribonucleotide triphosphates (dNTPs). This autophagy inducer was combined with COH29, an inhibitor developed in our laboratory that targets RR through a novel mechanism. The combination therapy showed synergistic effects on cytotoxicity in vitro and in an in vivo xenograft model. This cytotoxicity was blocked by knockdown of the autophagy protein ATG5 or addition of chloroquine, an autophagy inhibitor. The combined therapy also induced dNTP depletion and massive genomic instability, leading us to hypothesize that combining autophagy induction with RR inhibition can lead to mitotic catastrophe in rapidly dividing cells. We propose that this TMX + COH29 combined therapy may have clinical benefit. Furthermore, autophagy induction may be a general mechanism for augmenting the effects of chemotherapeutic agents

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“…Similarly, iron chelators, (ciclopirox, triapine and deferoxamine) and free radical scavengers (hydroxyurea) inhibit RRM2 [ 22 ]. The dimerization of RRM1 and RRM2 can also be blocked using the small-molecule drug COH29, which is currently being tested in clinical trials [ 36 , 37 ]. Although small-molecule inhibitors represent the primary strategy for RNR inhibition, siRNA-based approaches to target RNR are also being tested in clinical trials [ 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Inhibition of CHK1 sensitizes Ewing sarcoma cells to the ribonucleotide reductase inhibitor gemcitabine

et al. 2017

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Ewing sarcoma is a bone and soft tissue sarcoma that occurs in children and young adults. The EWS-FLI1 gene fusion is the driver mutation in most Ewing sarcoma tumors and functions, in part, as an aberrant transcription factor. We recently identified that Ewing sarcoma cells are sensitive to inhibition of ribonucleotide reductase (RNR), which catalyzes the formation of deoxyribonucleotides from ribonucleotides. In this report, we show that Ewing sarcoma cells are sensitive to treatment with clofarabine, which is a nucleoside analogue and allosteric inhibitor of RNR. However, clofarabine is a reversible inhibitor of RNR and we found that the effect of clofarabine is limited when using a short (6-hour) drug treatment. Gemcitabine, on the other hand, is an irreversible inhibitor of the RRM1 subunit of RNR and this drug induces apoptosis in Ewing sarcoma cells when used in both 6-hour and longer drug treatments. Treatment of Ewing sarcoma cells with gemcitabine also results in activation of checkpoint kinase 1 (CHK1), which is a critical mediator of cell survival in the setting of impaired DNA replication. Notably, inhibition of CHK1 function in Ewing sarcoma cells using a small-molecule CHK1 inhibitor, or siRNA knockdown, in combination with gemcitabine results in increased toxicity both in vitro and in vivo in a mouse xenograft experiment. Overall, our results provide insight into Ewing sarcoma biology and identify a candidate therapeutic target, and drug combination, in Ewing sarcoma.

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The Novel Ribonucleotide Reductase Inhibitor COH29 Inhibits DNA Repair In Vitro

Cited by 22 publications

References 35 publications

A Selective Small Molecule DNA2 Inhibitor for Sensitization of Human Cancer Cells to Chemotherapy

A Selective Small Molecule DNA2 Inhibitor for Sensitization of Human Cancer Cells to Chemotherapy

Autophagy induction causes a synthetic lethal sensitization to ribonucleotide reductase inhibition in breast cancer cells

Inhibition of CHK1 sensitizes Ewing sarcoma cells to the ribonucleotide reductase inhibitor gemcitabine

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