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 IC50 value 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.

Increased Thioredoxin-1 Expression Promotes Cancer Progression and Predicts Poor Prognosis in Patients with Gastric Cancer

“…In addition, PX-12 inhibits colorectal cancer cell migration and invasion [33] and enhances the sensitivity of acute myeloid leukemia cells to arsenic trioxide [34]. The antitumor effect of PX-12 is also associated with cell cycle arrest, intracellular increases in ROS levels, and GSH depletion [35, 36]. PX-12 has already been assessed in phase II trials for the treatment of advanced pancreatic cancer and in a phase Ib trial for the treatment of advanced gastrointestinal cancers [15, 37].…”

Thioredoxin promotes survival signaling events under nitrosative/oxidative stress associated with cancer development

“…PX-12 also affects cancer cell growth because it is a competitive inhibitor for TrxR1 in addition to its direct effects on Trx1 [79] . It also causes GSH depletion and cell cycle arrest leading to further cell death by apoptosis [80] and inhibits tubulin polymerization by cysteine oxidation [81] .…”

Methionine regulates the major physiological functions of animals

“…GSH发挥抗氧化 作用既可以来自外源性添加也可以来自于内源性的蛋 氨酸代谢. 饲粮中GSH可以在小肠部分吸收后合成 [43] , 并作为细胞抗氧化系统的主要成分, 直接清除自由基 [44,45] , 并且细胞可能失去将GSSG还 原成GSH的能力, 从而导致GSSG在胞质溶胶中积累, 打破原有的氧化还原平衡状态.…”