The Modified High-Density Survival Assay is the Useful Tool to Predict the Effectiveness of Fractionated Radiation Exposure

Kuwahara, Yoshikazu; Mori, Miyuki; Oikawa, T.; Shimura, Tsutomu; Ohtake, Yosuke; Mori, Shiro; Ohkubo, Yasuhito; Fukumoto, Manabu

doi:10.1269/jrr.09094

Cited by 35 publications

(41 citation statements)

References 14 publications

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“…In order to understand and conquer radioresistant tumors, we have established CRR cell lines. 20, 21 Profile of radiation-induced cell death under a microscope could be divided into two major types: cell death with apoptotic bodies and that lacking apoptotic bodies. We speculated that the latter was autophagic cell death.…”

Section: Discussionmentioning

confidence: 99%

“…20, 21 These cells continue to proliferate with daily exposure to 2 Gray (Gy) of X-rays for >30 days, which corresponds to the standard protocol of fractionated radiotherapy for cancer treatment. This study revealed that CRR cells were refractory to the induction of autophagy after irradiation and that facilitation of autophagy by rapamycin (RPM) abrogated the CRR phenotype.…”

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confidence: 99%

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Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

et al. 2011

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Radiotherapy is a well-established treatment for cancer. However, the existence of radioresistant cells is one of the major obstacles in radiotherapy. In order to understand the mechanism of cellular radioresistance and develop more effective radiotherapy, we have established clinically relevant radioresistant (CRR) cell lines, which continue to proliferate under daily exposure to 2 Gray (Gy) of X-rays for >30 days. X-ray irradiation significantly induced autophagic cells in parental cells, which was exiguous in CRR cells, suggesting that autophagic cell death is involved in cellular radiosensitivity. An autophagy inducer, rapamycin sensitized CRR cells to the level of parental cells and suppressed cell growth. An autophagy inhibitor, 3-methyladenine induced radioresistance of parental cells. Furthermore, inhibition of autophagy by knockdown of Beclin-1 made parental cells radioresistant to acute radiation. These suggest that the suppression of autophagic cell death but not apoptosis is mainly involved in cellular radioresistance. Therefore, the enhancement of autophagy may have a considerable impact on the treatment of radioresistant tumor.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

et al. 2011

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“…The modified high-density survival (HDS) assay was performed according to the method of Kuwahara et al (2010). Exponentially growing cells (5 × 10 5 ) were seeded in a 60 mm tissue culture dish (Asahi Techno Glass Co., LTD) and incubated in DMEM with 1% FBS for 48 h. The cells treated with various concentrations of IL-6 (0, 50, and 200 pg ml −1 ) were then exposed to 6 Gy of X-rays.…”

Section: Methodsmentioning

confidence: 99%

IL-6 controls resistance to radiation by suppressing oxidative stress via the Nrf2-antioxidant pathway in oral squamous cell carcinoma

et al. 2016

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Background:In promoting tumour malignancy IL-6 signalling is considered to have an important role. However, the biological roles of IL-6 on radiosensitivity in oral squamous cell carcinoma (OSCC) remain largely unclear. The objective of this study is to determine the effects and molecular mechanisms of IL-6 on radiosensitivity in OSCC.Methods:Two OSCC cell lines, and OSCC tissue samples with radioresistant cells were used. We examined the effects of IL-6, or tocilizumab, a humanised anti-human IL-6 receptor antibody, or both on radiosensitivity and DNA damage after X-ray irradiation in vitro. In addition, we investigated the involvement of the Nrf2-antioxidant pathway in IL-6-mediated radioresistant mechanisms using OSCC cell lines and tissues.Results:Increased levels of IL-6 suppressed radiation-induced cell death, and the blockade of IL-6 signalling by tocilizumab sensitised tumour cells to radiation. The radioresistant effect of IL-6 was associated with decreased DNA damage after radiation. We also found that IL-6 promotes the activation of not only the downstream molecule STAT3 but also the Nrf2-antioxidant pathway, leading to a significant decrease in oxidative stress by upregulating Mn-SOD.Conclusions:These results indicate that the blockade of IL-6 signalling combined with conventional radiotherapy could augment the treatment response and survival rate in patients with radioresistant OSCC.

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“…The HepG2-8960-R, HepG2-R, SAS-R and HeLa-R CRR cell lines were independently established from the parental HepG2, SAS and HeLa cell lines through a stepwise increase in X-ray dose exposure from 0.5 to 2 Gy/day [24]. The cells that continued to stably proliferate under exposure to 2 Gy/day of X-rays were defined as CRR cells.…”

Section: Cell Culturementioning

confidence: 99%

X-Ray Induced Mutation Frequency at the <i>Hypoxanthine Phosphoribosyltransferase</i> Locus in Clinically Relevant Radioresistant Cells

Kuwahara¹,

Roudkenar²,

Urushihara³

et al. 2017

IJMPCERO

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To elucidate the molecular mechanisms underlying cellular radioresistance, clinically relevant radioresistant cell lines were established via long-term exposure to X-rays with stepwise dose escalation. Established cells continue to proliferate despite exposure to 2 Gy X-rays/day for more than 30 days, a standard protocol in cancer radiotherapy. DNA repair fidelity in radioresistant and the parental cells by evaluating the mutation frequency at the hypoxanthine phosphoribosyltransferase (HPRT) locus after exposure to X-rays was determined. Mutation spectrum at the HPRT locus was examined by multiplex polymerase chain reaction. Rejoining kinetics of X-ray-induced DNA double strand breaks (dsbs) was evaluated by the detection of phosphorylated histone H2AX (γH2AX) after X-irradiation. The fold increase in the HPRT mutation frequency due to acute radiation was similar between radioresistant and the parental cell lines. However, fractionated radiation (FR) consisting of 2 Gy X-rays/day increased the mutation frequency at the HPRT locus in parental but not in radioresistant cells. Analysis of the FR-induced mutations at the HPRT locus revealed a high frequency of deletion mutations (>70%) in parental but not in

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The Modified High-Density Survival Assay is the Useful Tool to Predict the Effectiveness of Fractionated Radiation Exposure

Cited by 35 publications

References 14 publications

Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

IL-6 controls resistance to radiation by suppressing oxidative stress via the Nrf2-antioxidant pathway in oral squamous cell carcinoma

X-Ray Induced Mutation Frequency at the <i>Hypoxanthine Phosphoribosyltransferase</i> Locus in Clinically Relevant Radioresistant Cells

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The Modified High-Density Survival Assay is the Useful Tool to Predict the Effectiveness of Fractionated Radiation Exposure

Cited by 35 publications

References 14 publications

Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

Enhancement of autophagy is a potential modality for tumors refractory to radiotherapy

IL-6 controls resistance to radiation by suppressing oxidative stress via the Nrf2-antioxidant pathway in oral squamous cell carcinoma

X-Ray Induced Mutation Frequency at the &lt;i&gt;Hypoxanthine Phosphoribosyltransferase&lt;/i&gt; Locus in Clinically Relevant Radioresistant Cells

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X-Ray Induced Mutation Frequency at the <i>Hypoxanthine Phosphoribosyltransferase</i> Locus in Clinically Relevant Radioresistant Cells