Analyses of changes of cell properties specifically induced by heavy ion irradiation using viruses as analyzing tools

Abstract

Treatment of cancer using heavy ion beams has shown excellent therapeutic results. It is expected that heavy ion irradiation will specifically affect properties of irradiated cells. For this, we analyzed effects of irradiation with heavy ion beams, X-ray or UV using virological methods as tools.
(1) Enhanced susceptibility of irradiated cells to HIV-1 Human cells irradiated with heavy ions but not X-ray or UV became more susceptible to HIV-1 than unirradiated cells. We examined whether the expression of genes that may be involved in HIV-1 infection steps was specifically affected by heavy ion irradiation: The expression of NF-kB was enhanced while that of Ku-80 or PARP was reduced.
(2) Effects of heavy ion irradiation on retrotransposition One of repeated genetic elements, LINE, is consisting 17% of the human genome and has a retrovirus-like genetic structure. We examined whether irradiation with heavy ions, X-ray, UV, etc. will enhance its transposition. Irradiation of cells by them lead to enhanced retrotransposition, but their rates were similar among different types of irradiation.
(3) Establishment of human cells expressing pprA and their susceptibilities to irradiation
D. radiodurans is a bacterium highly resistant to X-ray irradiation. pprA was identified as one of genes responsible for this trait. We have examined whether changes of cellular functions specific to heavy ion irradiation can be clarified using pprA gene. PprA protein was localized making peculiar patterns in cells. The cells became slightly more resistant to irradiation than the parental cells. We noticed that irradiation with heavy ions but not with X-ray or UV can evoke specific cellular responses which were detected upon analyses of genes possibly involved in HIV-1 infection