Abstract

Tumors continued to grow in many cancer patients after they received radiation therapy, which required higher radiation dose. But when high dose of radiation damaged tumor cells, some normal cells were also killed, which was the largest obstacle that doctors cannot use high dose radiation. If the radiation resistant genes were transformed into the normal tissues, the normal tissues would be protected from being damaged when patients were irradiated. The tolerating doses of all radioresistant (radiation-resistant) genes for this aim were lower than clinical requirement. There were many strong radiation resistant genes inDeinococcus radiodurans genome. If these genes can play their radiation resistant roles in human cells, the predicaments that radiation therapy faced now would be conquered. DR1709 was a radiation resistant gene from D. radiodurans. We found that Escherichia colitransformed with DR1709 had much higher radioresistance than the control. In this paper, human bone marrow cell line, KG1a, was transformed with DR1709. Cells contained DR1709 and the control cells were treated with gamma radiation. Results showed that cells containing DR1709 had much higher survival fraction than those cells which were only transformed with the net vector. After being transformed with DR1709, the expression of GLRX2 was induced in KG1a, while the expression of the putative holocytochrome c-type synthetase was suppressed. Genes from D. radiodurans can be used as a shield for normal cells when they are irradiated. But there were many questions to be resolved before this result was used in clinical treatment.

Key words: Radioresistance, DR1709, KG1a, mitochondria.