Antitumor Indolequinones Induced Apoptosis in Human Pancreatic Cancer Cells via Inhibition of Thioredoxin Reductase and Activation of Redox Signaling

作者：Yan Chao; Siegel David; Newsome Jeffery; Chilloux Aurelie; Moody Christopher J; Ross David^*

来源：Molecular Pharmacology, 2012, 81(3): 401-410.

DOI：10.1124/mol.111.076091

Indolequinones (IQs) were developed as potential antitumor agents against human pancreatic cancer. IQs exhibited potent antitumor activity against the human pancreatic cancer cell line MIA PaCa-2 with growth inhibitory IC50 values in the low nanomolar range. IQs were found to induce time-and concentrationdependent apoptosis and to be potent inhibitors of thioredoxin reductase 1 (TR1) in MIA PaCa-2 cells at concentrations equivalent to those inducing growth-inhibitory effects. The mechanism of inhibition of TR1 by the IQs was studied in detail in cell-free systems using purified enzyme. The C-terminal selenocysteine of TR1 was characterized as the primary adduction site of the IQ-derived reactive iminium using liquid chromatog-raphy-tandem mass spectrometry analysis. Inhibition of TR1 by IQs in MIA PaCa-2 cells resulted in a shift of thioredoxin-1 redox state to the oxidized form and activation of the p38/ c-Jun NH 2 -terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathway. Oxidized thioredoxin is known to activate apoptosis signal-regulating kinase 1, an upstream activator of p38/JNK in the MAPK signaling cascade and this was confirmed in our study providing a potential mechanism for IQ-induced apoptosis. These data describe the redox and signaling events involved in the mechanism of growth inhibition induced by novel inhibitors of TR1 in human pancreatic cancer cells.

• 出版日期2012-3