title: PX-12-induced HeLa cell death is associated with oxidative stress and GSH depletion.
abstract: PX-12, as an inhibitor of thioredoxin (Trx), has antitumor activity. However, little is known about the toxicological effect of PX-12 on cervical cancer cells. In the present study, the growth inhibitory effects of PX-12 on HeLa cervical cancer cells in association with reactive oxygen species (ROS) and glutathione (GSH) levels were investigated. Based on MTT assays, PX-12 inhibited the growth of HeLa cells with an IC50value of ~7 μM at 72 h. DNA flow cytometry analysis indicated that 5 and 10 μM PX-12 significantly induced a G2/M phase arrest of the cell cycle. PX-12 also increased the number of dead cells and annexin V-fluorescein isothiocyanate-positive cells, which was accompanied by the loss of mitochondrial membrane potential. All the investigated caspase inhibitors significantly rescued certain cells from PX-12-induced HeLa cell death. With respect to ROS and GSH levels, PX-12 increased ROS levels (including O2•-) in HeLa cells and induced GSH depletion. N-acetyl cysteine markedly reduced the levels of O2•-in PX-12-treated HeLa cells, and prevented apoptotic cell death and GSH depletion in these cells. By contrast, L-buthionine sulfoximine intensified cell death and GSH depletion in PX-12-treated HeLa cells. To conclude, this is the first study to demonstrate that PX-12 inhibits the growth of HeLa cells via G2/M phase arrest, as well as inhibiting apoptosis; the effect was associated with intracellular increases in ROS levels and GSH depletion.
authors.affiliation: Department of Physiology, Medical School, Research Institute for Endocrine Sciences, Chonbuk National University, Jeonju 561-180, Republic of Korea.
authors.forename: Hye Rim
authors.initials: HR
authors.lastname: Shin
authors.forename: Bo Ra
authors.initials: BR
authors.lastname: You
authors.forename: Woo Hyun
authors.initials: WH
authors.lastname: Park
keywords: HeLa; PX-12; cell death; reactive oxygen species; thioredoxin