1062 Poster Double strand breaks induced by Carbon ion irradiation in prostate cancer cells

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.

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Involvement of HIF-1α in the Detection, Signaling, and Repair of DNA Double-Strand Breaks after Photon and Carbon-Ion Irradiation

Cancers ◽

10.3390/cancers13153833 ◽

2021 ◽

Vol 13 (15) ◽

pp. 3833

Author(s):

Anne-Sophie Wozny ◽

Arnaud Gauthier ◽

Gersende Alphonse ◽

Céline Malésys ◽

Virginie Varoclier ◽

...

Keyword(s):

Ion Irradiation ◽

Hypoxia Inducible Factor ◽

Therapeutic Benefit ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Carbon Ion ◽

Oxygen Homeostasis ◽

Γh2ax Foci ◽

Main Regulator

Hypoxia-Inducible Factor 1α (HIF-1α), which promotes cancer cell survival, is the main regulator of oxygen homeostasis. Hypoxia combined with photon and carbon ion irradiation (C-ions) stabilizes HIF-1α. Silencing HIF-1α under hypoxia leads to substantial radiosensitization of Head-and-Neck Squamous Cell Carcinoma (HNSCC) cells after both photons and C-ions. Thus, this study aimed to clarify a potential involvement of HIF-1α in the detection, signaling, and repair of DNA Double-Strand-Breaks (DSBs) in response to both irradiations, in two HNSCC cell lines and their subpopulations of Cancer-Stem Cells (CSCs). After confirming the nucleoshuttling of HIF-1α in response to both exposure under hypoxia, we showed that silencing HIF-1α in non-CSCs and CSCs decreased the initiation of the DSB detection (P-ATM), and increased the residual phosphorylated H2AX (γH2AX) foci. While HIF-1α silencing did not modulate 53BP1 expression, P-DNA-PKcs (NHEJ-c) and RAD51 (HR) signals decreased. Altogether, our experiments demonstrate the involvement of HIF-1α in the detection and signaling of DSBs, but also in the main repair pathways (NHEJ-c and HR), without favoring one of them. Combining HIF-1α silencing with both types of radiation could therefore present a potential therapeutic benefit of targeting CSCs mostly present in tumor hypoxic niches.

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Efficient Rejoining of DNA Double-Strand Breaks despite Increased Cell-Killing Effectiveness following Spread-Out Bragg Peak Carbon-Ion Irradiation

Frontiers in Oncology ◽

10.3389/fonc.2016.00028 ◽

2016 ◽

Vol 6 ◽

Cited By ~ 9

Author(s):

Nicole B. Averbeck ◽

Jana Topsch ◽

Michael Scholz ◽

Wilma Kraft-Weyrather ◽

Marco Durante ◽

...

Keyword(s):

Bragg Peak ◽

Ion Irradiation ◽

Cell Killing ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Carbon Ion ◽

Spread Out Bragg Peak

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Repair Kinetics of DNA Double Strand Breaks Induced by Simulated Space Radiation

Life ◽

10.3390/life10120341 ◽

2020 ◽

Vol 10 (12) ◽

pp. 341

Author(s):

Takashi Oizumi ◽

Rieko Ohno ◽

Souichiro Yamabe ◽

Tomoo Funayama ◽

Asako J. Nakamura

Keyword(s):

Dna Damage ◽

Ion Irradiation ◽

Space Radiation ◽

Double Strand Breaks ◽

Dependent Manner ◽

Dna Double Strand Breaks ◽

Dsb Repair ◽

Strand Breaks ◽

Carbon Ion ◽

Kinetics Of

Radiation is unavoidable in space. Energetic particles in space radiation are reported to induce cluster DNA damage that is difficult to repair. In this study, normal human fibroblasts were irradiated with components of space radiation such as proton, helium, or carbon ion beams. Immunostaining for γ-H2AX and 53BP1 was performed over time to evaluate the kinetics of DNA damage repair. Our data clearly show that the repair kinetics of DNA double strand breaks (DSBs) induced by carbon ion irradiation, which has a high linear energy transfer (LET), are significantly slower than those of proton and helium ion irradiation. Mixed irradiation with carbon ions, followed by helium ions, did not have an additive effect on the DSB repair kinetics. Interestingly, the mean γ-H2AX focus size was shown to increase with LET, suggesting that the delay in repair kinetics was due to damage that is more complex. Further, the 53BP1 focus size also increased in an LET-dependent manner. Repair of DSBs, characterized by large 53BP1 foci, was a slow process within the biphasic kinetics of DSB repair, suggesting non-homologous end joining with error-prone end resection. Our data suggest that the biological effects of space radiation may be significantly influenced by the dose as well as the type of radiation exposure.

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