Mechanisms involved in the elevation of glutathione in RAW 264.7 cells exposed to low doses of γ-rays

Shuji Kojima, Kazuo Teshima, Kiyonori Yamaoka

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We examined the mechanisms of the elevation of glutathione level induced in macrophage-like RAW 264.7 cells by low doses of γ-rays. The level increased soon after exposure of the cells to 50 cGy of γ-rays, peaked between 3 hours and 6 hours and returned almost to the time 0 value by 24 hours post-irradiation. Doses between 25 and 100 cGy significantly increased the glutathione level at 4 hours post-irradiation. However, there was no significant elevation at doses of more than 100 cGy or less than 25 cGy. When the effect of dose rate was examined at a constant absorbed dose of 50 cGy, dose rates of more than 50 cGy/minute significantly increased the GSH level at 4 hours post-irradiation. It was also shown that the elevation of glutathione level in cells irradiated with low doses of γ-rays followed the induction of mRNA coding for γ-glutamylcysteine synthetase (γ-GCS), a rate-limiting enzyme of the de novo glutathione synthesis pathway. When the cells were exposed to the radiation in the presence of genistein, calphostin C or nifedipine, the elevations of glutathione and γ-GCS mRNA expression were both mostly blocked. EGTA also strongly inhibited these elevations. These results suggest that the tyrosine kinase, calcium channel and protein kinase C activities play an essential role in the low-dose-radiation-induced elevation of cellular glutathione.

Original languageEnglish
Pages (from-to)1589-1594
Number of pages6
JournalAnticancer research
Volume20
Issue number3 A
Publication statusPublished - Aug 30 2000

Keywords

  • Calcium-channel
  • Glutathione
  • Low-dose γ-rays
  • Protein kinase C
  • Tyrosine kinase

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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