US EPA

2088511 

Journal Article 

Effects of arsenic on modification of promyelocytic leukemia (PML): PML responds to low levels of arsenite 

Hirano, S; Watanabe, T; Kobayashi, Y 

In Press 

Yes 

Toxicology and Applied Pharmacology
ISSN: 0041-008X
EISSN: 1096-0333 

273 

3 

590-599 

English 

24135626 

10.1016/j.taap.2013.10.004 

WOS:000328711700019 

Inorganic arsenite (iAs(3+)) is a two-edged sword. iAs(3+) is a well-known human carcinogen; nevertheless, it has been used as a therapeutic drug for acute promyelocytic leukemia (APL), which is caused by a fusion protein comprising retinoic acid receptor-α and promyelocytic leukemia (PML). PML, a nuclear transcription factor, has a RING finger domain with densely positioned cysteine residues. To examine PML-modulated cellular responses to iAs(3+), CHO-K1 and HEK293 cells were each used to establish cell lines that expressed ectopic human PML. Overexpression of PML increased susceptibility to iAs(3+) in CHO-K1 cells, but not in HEK293 cells. Exposure of PML-transfected cells to iAs(3+) caused PML to change from a soluble form to less soluble forms, and this modification of PML was observable even with just 0.1μM iAs(3+) (7.5ppb). Western blot and immunofluorescent microscopic analyses revealed that the biochemical changes of PML were caused at least in part by conjugation with small ubiquitin-like modifier proteins (SUMOylation). A luciferase reporter gene was used to investigate whether modification of PML was caused by oxidative stress or activation of antioxidant response element (ARE) in CHO-K1 cells. Modification of PML protein occurred faster than activation of the ARE in response to iAs(3+), suggesting that PML was not modified as a consequence of oxidative stress-induced ARE activation. 

Arsenic; Promyelocytic leukemia; SUMO; Western blot; Oxidative stress; ICP-MS