Benzyl Isothiocyanate (BITC) Induces Reactive Oxygen Species-dependent Repression of STAT3 Protein by Down-regulation of Specificity Proteins in Pancreatic Cancer

• Published in: The Journal of biological chemistry 2016-12, Vol.291 (53), p.27122-27133
• Main Authors: Kasiappan, Ravi, Jutooru, Indira, Karki, Keshav, Hedrick, Erik, Safe, Stephen
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Blotting, Western; Cell Movement - drug effects; Cell Proliferation - drug effects; Gene Expression Regulation, Neoplastic - drug effects; Gene Regulation; Humans; Isothiocyanates - pharmacology; Mice; Mice, Nude; Myc (c-Myc); pancreatic cancer; Pancreatic Neoplasms - drug therapy; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; reactive oxygen species (ROS); Reactive Oxygen Species - metabolism; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Sp Transcription Factors - antagonists & inhibitors; Sp Transcription Factors - genetics; Sp Transcription Factors - metabolism; specificity protein 1 (Sp1); STAT3; STAT3 Transcription Factor - antagonists & inhibitors; STAT3 Transcription Factor - genetics; STAT3 Transcription Factor - metabolism; STAT3 Transcription Factor - therapeutic use; Tumor Cells, Cultured; Xenograft Model Antitumor Assays
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M116.746339

The antineoplastic agent benzyl isothiocyanate (BITC) acts by targeting multiple pro-oncogenic pathways/genes, including signal transducer and activator of transcription 3 (STAT3); however, the mechanism of action is not well known. As reported previously, BITC induced reactive oxygen species (ROS) in Panc1, MiaPaCa2, and L3.6pL pancreatic cancer cells. This was accompanied by induction of apoptosis and inhibition of cell growth and migration, and these responses were attenuated in cells cotreated with BITC plus glutathione (GSH). BITC also decreased expression of specificity proteins (Sp) Sp1, Sp3, and Sp4 transcription factors (TFs) and several pro-oncogenic Sp-regulated genes, including STAT3 and phospho-STAT3 (pSTAT3), and GSH attenuated these responses. Knockdown of Sp TFs by RNA interference also decreased STAT3/pSTAT3 expression. BITC-induced ROS activated a cascade of events that included down-regulation of c-Myc, and it was also demonstrated that c-Myc knockdown decreased expression of Sp TFs and STAT3. These results demonstrate that in pancreatic cancer cells, STAT3 is an Sp-regulated gene that can be targeted by BITC and other ROS inducers, thereby identifying a novel therapeutic approach for targeting STAT3.