p53-mediated enhancement of radiosensitivity by selenophosphate synthetase 1 overexpression

Hyun Ju Chung, Sun Il Yoon, Sun Hye Shin, Yeon A. Koh, Su Jae Lee, Yun Sil Lee, Sangwoo Bae

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Selenium has been associated with cancer prevention. Despite vast knowledge of selenium effect on various health conditions, functional characterization of selenium metabolic enzymes on cellular physiology has been limited. Therefore, to gain insight into the mechanisms underlying cancer prevention by selenium, we investigated sps1, one of the two human selenophosphate synthetase genes for its role in cancer cell's response to ionizing radiat ion. Although stable expression of Sps1 protein per se had little effect on cell proliferation, concurrent irradiation decreased viability of the sps1 cell line. The increased sensitivity of the cell lines to ionizing radiation was correlated with increased p53 activity as well as with simultaneous up- and downregulation of Bax and Bcl2, respectively. Knockdown of sps1 and p53 by small interfering RNA method revealed that the level of p53 was proportional to that of Sps1 and that the increased radiosensitivity was dependent upon p53. Sps1 cell lines displayed decreased level of reactive oxygen species (ROS) with concomitant increase of certain redox enzymes. Furthermore, p53 activity was regulated by cellular redox via Ref1 in sps1 cell lines. Collectively, our results demonstrated that sps1 was able to affect cell viability upon ionizing radiation via modulation of p53 activity. They further suggest that Sps1 and its reaction product selenophosphate might be involved in cancer prevention in a p53-dependent manner and could be applied to development of a novel cancer therapy.

Original languageEnglish
Pages (from-to)131-141
Number of pages11
JournalJournal of Cellular Physiology
Issue number1
StatePublished - Oct 2006


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