Objectives

Increased expression of glutaminase (GLS) has been found to correlate with more aggressive disease and poorer prognosis in patients with several types of cancer, including breast, lung, and pancreatic cancer. G9a histone methyltransferase inhibitors may have anticancer activity. The present study assessed whether BIX01294 (BIX), a G9a histone methyltransferase inhibitor, can inhibit glutaminase (GLS) in pancreatic ductal adenocarcinoma (PDAC) cells.

Methods

The effects of BIX on mitochondrial metabolism in PDAC cells were evaluated by targeted liquid chromatography–tandem mass spectrometry (LC-MS/MS) metabolomic analysis. To assess the impact of BIX on glutathione dynamics, real-time changes in glutathione levels were monitored by FreSHtracer-based GSH assays.

Results

BIX significantly inhibited the growth of PDAC cells, both in vitro and in vivo, and robustly induced apoptotic cell death. BIX significantly increased the cellular NADP⁺/NADPH ratio and decreased the ratio of reduced-to-oxidized glutathione (GSH:GSSG). In addition, BIX decreased GSH levels and increased ROS levels. N-acetyl-l-cysteine (NAC) supplementation dramatically rescued PDAC cells from BIX-induced apoptosis. Furthermore, BIX inhibited the transcription of GLS by inhibiting Jumonji-domain histone demethylases but not G9a histone methyltransferase. One Jumonji-domain histone demethylase, KDM6B, epigenetically regulated GLS expression by binding to the GLS gene promoter.

Conclusions

Collectively, these findings suggest that BIX could be a potent therapeutic agent in patients with PDAC through its inhibition of GLS-mediated cellular redox balance.