Induction of DNA Double-Strand Breaks and Cellular Migration Through Bystander Effects in Cells Irradiated With the Slit-Type Microplanar Beam of the Spring-8 Synchrotron

Genro Kashino, Takeshi Kondoh, Nobuteru Nariyama, Keiji Umetani, Takuji Ohigashi, Kunio Shinohara, Ai Kurihara, Manabu Fukumoto, Hiroki Tanaka, Akira Maruhashi, Minoru Suzuki, Yuko Kinashi, Yong Liu, Shin ichiro Masunaga, Masami Watanabe, Koji Ono

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Purpose: To determine whether glioma cells irradiated with a microplanar X-ray beam exert bystander effects. Methods and Materials: Microplanar beam irradiation of glioma cells in vitro was done using the SPring-8 synchrotron radiation facility. The amount of DNA double-strand breaks (dsbs) was measured by the fluorescence intensity of phosphorylated H2AX or the number of 53BP1 foci. The dose distribution in a cell population exposed to a single microplanar beam was determined by the amount of phosphorylated H2AX-positive cells. Bystander effects were determined by counting the number of 53BP1 foci in nonirradiated cells treated with conditioned medium from cultures of irradiated cells. Results: More DNA dsbs were detected in cells adjacent to an area irradiated by the single beam than in cells in distant, nonirradiated areas as a result of bystander effects caused by scattered X-rays and DNA dsbs. In support of this, more 53BP1 foci were observed in nonirradiated, conditioned medium-treated cells than in control cells (i.e., cells not treated with irradiation or conditioned medium). These results suggest that DNA dsbs were induced in nonirradiated cells by soluble factors in the culture medium. In addition, we observed cellular migration into areas irradiated with peak doses, suggesting that irradiated cells send signals that cause nonirradiated cells to migrate toward damaged cells. Conclusions: Bystander effects are produced by factors secreted as a result of slit-type microplanar X-ray beam irradiation.

Original languageEnglish
Pages (from-to)229-236
Number of pages8
JournalInternational Journal of Radiation Oncology Biology Physics
Volume74
Issue number1
DOIs
Publication statusPublished - 2009 May 1
Externally publishedYes

Keywords

  • Bystander effect
  • Cellular migration
  • DNA double-strand breaks
  • Radiotherapy
  • Slit microbeam

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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