Open AccessDithiolethione compounds inhibit Akt signaling in human breast and lung cancer cells by increasing PP2A activity
Author(s) -
Christopher Switzer,
Lisa A. Ridnour,
Robert Cheng,
Anna Sparatore,
Piero Del Soldato,
Terry W. Moody,
Michael P. Vitek,
D. A. Roberts,
David A. Wink
Publication year - 2009
Publication title -
oncogene
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.395
H-Index - 342
eISSN - 1476-5594
pISSN - 0950-9232
DOI - 10.1038/onc.2009.244
Subject(s) - protein kinase b , protein phosphatase 2 , phosphorylation , biology , okadaic acid , signal transduction , cancer research , microbiology and biotechnology , epidermal growth factor , pi3k/akt/mtor pathway , endocrinology , receptor , biochemistry , phosphatase
The chemopreventative effects of dithiolethione compounds are attributed to their activation of antioxidant response elements (AREs) by reacting with the Nrf2/Keap1 protein complex. In this study, we show antiproliferative effects of the dithiolethione compound ACS-1 in human cancer cell lines (A549 and MDA-MB-231) by increasing the activity of the tumor suppressor protein phoshatase 2A (PP2A). ACS-1 inhibited epidermal growth factor (EGF)-induced cellular proliferation in a concentration- and time-dependent manner. Akt activation, as determined by serine-473 phosphorylation, was inhibited by ACS-1 in cells stimulated with either EGF or fibronectin. Furthermore, ACS-1 inhibited mammalian target of rapamycin signaling and decreased c-myc protein levels. ACS-1 did not proximally alter EGF receptor or integrin signaling, but caused a concentration-dependent increase in PP2A activity. The effect of ACS-1 on Akt activation was not observed in the presence of the PP2A inhibitor okadaic acid. ACS-1 effects on PP2A activity were independent of ARE activation and cAMP formation. In addition to ACS-1, other dithiolethione compounds showed similar effects in reducing Akt activation, suggesting that this class of compounds may have other effects beyond chemoprevention.