scholarly journals In Vitro Evaluation of No-carrier-added Radiolabeled Cisplatin ([189, 191Pt]cisplatin) Emitting Auger Electrons

2021 ◽  
Author(s):  
Honoka Obata ◽  
Atsushi B. Tsuji ◽  
Hitomi Sudo ◽  
Aya Sugyo ◽  
Katsuyuki Minegishi ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Short Range ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Primary Target ◽  
Auger Electrons ◽  
Strand Breaks ◽  
Chemical Damage ◽  
No Carrier Added

Due to their short range (2–500 nm), Auger electrons (Auger e-) have the potential to induce nano-scale physiochemical damage to biomolecules. Although DNA is the primary target of Au-ger e-, it remains challenging to maximize the interaction between Auger e- and DNA. To assess the DNA-damaging effect of Auger e- released as close as possible to DNA without chemical damage, we radio-synthesized no-carrier-added (n.c.a.) [189, 191Pt]cisplatin and evaluated both its in vitro properties and DNA-damaging effect. Cellular uptake, intracellular distribution, and DNA binding were investigated, and DNA double-strand breaks (DSBs) were evaluated by im-munofluorescence staining of γH2AX and gel electrophoresis of plasmid DNA. Approximately 20% of intracellular radio-Pt was in a nucleus, and about 2% of intra-nucleus radio-Pt bound to DNA, although uptake of n.c.a. radio-cisplatin was low (0.6% incubated dose after 25-h incuba-tion), resulting in the frequency of cells with γH2AX foci was low (1%). Nevertheless, some cells treated with radio-cisplatin had γH2AX aggregates unlike non-radioactive cisplatin. These findings suggest n.c.a. radio-cisplatin binding to DNA causes severe DSBs by release of Auger e- very close to DNA without chemical damage by carriers. Efficient radio-drug delivery to DNA is necessary for successful clinical application of Auger e-.

scholarly journals In Vitro Evaluation of No-Carrier-Added Radiolabeled Cisplatin ([189, 191Pt]cisplatin) Emitting Auger Electrons

2021 ◽  
Vol 22 (9) ◽  
pp. 4622
Author(s):  
Honoka Obata ◽  
Atsushi B. Tsuji ◽  
Hitomi Sudo ◽  
Aya Sugyo ◽  
Katsuyuki Minegishi ◽  
...  
Keyword(s):  
Short Range ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Primary Target ◽  
Auger Electrons ◽  
Strand Breaks ◽  
Chemical Damage ◽  
Γh2ax Foci ◽  
No Carrier Added

Due to their short-range (2–500 nm), Auger electrons (Auger e−) have the potential to induce nano-scale physiochemical damage to biomolecules. Although DNA is the primary target of Auger e−, it remains challenging to maximize the interaction between Auger e− and DNA. To assess the DNA-damaging effect of Auger e− released as close as possible to DNA without chemical damage, we radio-synthesized no-carrier-added (n.c.a.) [189, 191Pt]cisplatin and evaluated both its in vitro properties and DNA-damaging effect. Cellular uptake, intracellular distribution, and DNA binding were investigated, and DNA double-strand breaks (DSBs) were evaluated by immunofluorescence staining of γH2AX and gel electrophoresis of plasmid DNA. Approximately 20% of intracellular radio-Pt was in a nucleus, and about 2% of intra-nucleus radio-Pt bound to DNA, although uptake of n.c.a. radio-cisplatin was low (0.6% incubated dose after 25-h incubation), resulting in the frequency of cells with γH2AX foci was low (1%). Nevertheless, some cells treated with radio-cisplatin had γH2AX aggregates unlike non-radioactive cisplatin. These findings suggest n.c.a. radio-cisplatin binding to DNA causes severe DSBs by the release of Auger e− very close to DNA without chemical damage by carriers. Efficient radio-drug delivery to DNA is necessary for successful clinical application of Auger e−.

scholarly journals Focused ultrasound radiosensitizes human cancer cells by enhancement of DNA damage

2021 ◽  
Author(s):  
Xinrui Zhang ◽  
Mariana Bobeica ◽  
Michael Unger ◽  
Anastasia Bednarz ◽  
Bjoern Gerold ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Dna Damage ◽  
Cancer Cells ◽  
Metabolic Activity ◽  
Focused Ultrasound ◽  
Double Strand Breaks ◽  
High Intensity Focused Ultrasound ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

Abstract Purpose High-intensity focused ultrasound (HIFU/FUS) has expanded as a noninvasive quantifiable option for hyperthermia (HT). HT in a temperature range of 40–47 °C (thermal dose CEM43 ≥ 25) could work as a sensitizer to radiation therapy (RT). Here, we attempted to understand the tumor radiosensitization effect at the cellular level after a combination treatment of FUS+RT. Methods An in vitro FUS system was developed to induce HT at frequencies of 1.147 and 1.467 MHz. Human head and neck cancer (FaDU), glioblastoma (T98G), and prostate cancer (PC-3) cells were exposed to FUS in ultrasound-penetrable 96-well plates followed by single-dose X‑ray irradiation (10 Gy). Radiosensitizing effects of FUS were investigated by cell metabolic activity (WST‑1 assay), apoptosis (annexin V assay, sub-G1 assay), cell cycle phases (propidium iodide staining), and DNA double-strand breaks (γH2A.X assay). Results The FUS intensities of 213 (1.147 MHz) and 225 W/cm2 (1.467 MHz) induced HT for 30 min at mean temperatures of 45.20 ± 2.29 °C (CEM43 = 436 ± 88) and 45.59 ± 1.65 °C (CEM43 = 447 ± 79), respectively. FUS improves the effect of RT significantly by reducing metabolic activity in T98G cells 48 h (RT: 96.47 ± 8.29%; FUS+RT: 79.38 ± 14.93%; p = 0.012) and in PC-3 cells 72 h (54.20 ± 10.85%; 41.01 ± 11.17%; p = 0.016) after therapy, but not in FaDu cells. Mechanistically, FUS+RT leads to increased apoptosis and enhancement of DNA double-strand breaks compared to RT alone in T98G and PC-3 cells. Conclusion Our in vitro findings demonstrate that FUS has good potential to sensitize glioblastoma and prostate cancer cells to RT by mainly enhancing DNA damage.

scholarly journals The 9-1-1 Complex Controls Mre11 Nuclease and Checkpoint Activation during Short-Range Resection of DNA Double-Strand Breaks

Cell Reports ◽  
2020 ◽  
Vol 33 (3) ◽  
pp. 108287
Author(s):  
Elisa Gobbini ◽  
Erika Casari ◽  
Chiara Vittoria Colombo ◽  
Diego Bonetti ◽  
Maria Pia Longhese
Keyword(s):  
Short Range ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Checkpoint Activation ◽  
Strand Breaks

scholarly journals DNA double-strand breaks in the Toxoplasma gondii-infected cells by the action of reactive oxygen species

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Haohan Zhuang ◽  
Chaoqun Yao ◽  
Xianfeng Zhao ◽  
Xueqiu Chen ◽  
Yimin Yang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Toxoplasma Gondii ◽  
Double Strand Breaks ◽  
Host Cells ◽  
Oxygen Species ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Damage Response ◽  
Infected Cells

Abstract Background Toxoplasma gondii is an obligate parasite of all warm-blooded animals around the globe. Once infecting a cell, it manipulates the host’s DNA damage response that is yet to be elucidated. The objectives of the present study were three-fold: (i) to assess DNA damages in T. gondii-infected cells in vitro; (ii) to ascertain causes of DNA damage in T. gondii-infected cells; and (iii) to investigate activation of DNA damage responses during T. gondii infection. Methods HeLa, Vero and HEK293 cells were infected with T. gondii at a multiplicity of infection (MOI) of 10:1. Infected cells were analyzed for a biomarker of DNA double-strand breaks (DSBs) γH2AX at 10 h, 20 h or 30 h post-infection using both western blot and immunofluorescence assay. Reactive oxygen species (ROS) levels were measured using 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA), and ROS-induced DNA damage was inhibited by a ROS inhibitor N-acetylcysteine (NAC). Lastly, DNA damage responses were evaluated by detecting the active form of ataxia telangiectasia mutated/checkpoint kinase 2 (ATM/CHK2) by western blot. Results γH2AX levels in the infected HeLa cells were significantly increased over time during T. gondii infection compared to uninfected cells. NAC treatment greatly reduced ROS and concomitantly diminished γH2AX in host cells. The phosphorylated ATM/CHK2 were elevated in T. gondii-infected cells. Conclusions Toxoplasma gondii infection triggered DNA DSBs with ROS as a major player in host cells in vitro. It also activated DNA damage response pathway ATM/CHK2. Toxoplasma gondii manages to keep a balance between survival and apoptosis of its host cells for the benefit of its own survival.

scholarly journals A global view of meiotic double-strand break end resection

Science ◽  
2017 ◽  
Vol 355 (6320) ◽  
pp. 40-45 ◽  
Author(s):  
Eleni P. Mimitou ◽  
Shintaro Yamada ◽  
Scott Keeney
Keyword(s):  
Meiotic Recombination ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Naked Dna ◽  
Global View ◽  
Genome Wide ◽  
End Resection

DNA double-strand breaks that initiate meiotic recombination are exonucleolytically processed. This 5′→3′ resection is a central, conserved feature of recombination but remains poorly understood. To address this lack, we mapped resection endpoints genome-wide at high resolution inSaccharomyces cerevisiae. Full-length resection requires Exo1 exonuclease and the DSB-responsive kinase Tel1, but not Sgs1 helicase. Tel1 also promotes efficient and timely resection initiation. Resection endpoints display pronounced heterogeneity between genomic loci that reflects a tendency for nucleosomes to block Exo1, yet Exo1 also appears to digest chromatin with high processivity and at rates similar to naked DNA in vitro. This paradox points to nucleosome destabilization or eviction as a defining feature of the meiotic resection landscape.

Sign in / Sign up

Export Citation Format

Share Document