Dual specificity mitogen-activated protein kinase (MAPK) phosphatases [dual specificity phosphatase/MAP kinase phosphatase (DUSP-MKP)] have been hypothesized to maintain cancer cell survival by buffering excessive MAPK signaling caused by upstream activating oncogenic products. A large and diverse body of literature suggests that genetic depletion of DUSP-MKPs can reduce tumorigenicity, suggesting that hyperactivating MAPK signaling by DUSP-MKP inhibitors could be a novel strategy to selectively affect the transformed phenotype. Through in vivo structure-activity relationship studies in transgenic zebrafish we recently identified a hyperactivator of fibroblast growth factor signaling [(E)-2-benzylidene-5-bromo-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI-215)] that is devoid of developmental toxicity and restores defective MAPK activity caused by overexpression of DUSP1 and DUSP6 in mammalian cells. Here, we hypothesized that BCI-215 could selectively affect survival of transformed cells. In MDA-MB-231 human breast cancer cells, BCI-215 inhibited cell motility, caused apoptosis but not primary necrosis, and sensitized cells to lymphokine-activated killer cell activity. Mechanistically, BCI-215 induced rapid and sustained phosphorylation of extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK) in the absence of reactive oxygen species, and its toxicity was partially rescued by inhibition of p38 but not JNK or ERK. BCI-215 also hyperactivated MKK4/SEK1, suggesting activation of stress responses. Kinase phosphorylation profiling documented BCI-215 selectively activated MAPKs and their downstream substrates, but not receptor tyrosine kinases, SRC family kinases, AKT, mTOR, or DNA damage pathways. Our findings support the hypothesis that BCI-215 causes selective cancer cell cytotoxicity in part through non-redox-mediated activation of MAPK signaling, and the findings also identify an intersection with immune cell killing that is worthy of further exploration.
- Received December 23, 2016.
- Accepted January 30, 2017.
↵1 Current affiliation: Walter Reed Army Institute of Research, Silver Spring, Maryland.
↵2 Current affiliation: College of American Pathologists, Northfield, Illinois.
This project was supported in part by the National Institutes of Health National Cancer Institute [Grants CA147985 and CA181450]; the Kennedy Shriver National Institute of Child Health and Human Development [Grant HD053287]; DARPA Big Mechanism Proposal [DARPA-BAA-14-14]; and Automated Integration of Mechanisms in Cancer [AIMCancer Award W911NF-14-1-0422]. K.D. was supported by the Doris Duke Foundation Academy for Clinical Research, University of Pittsburgh (M.T.L.). This project used the University of Pittsburgh Cancer Institute Chemical Biology and Flow and Imaging Cytometry Core Facilities that are supported in part by Award P30CA047904.
Part of this work was presented as follows: Vollmer L, Vernetti L, Bakan A, Korotchenko V, Bahar I, Day B, Tsang M, and Vogt A (2014) A non-redox reactive allosteric inhibitor of MAPK phosphatases with selective toxicity to human cancer cells. AACR Annual Meeting; 2014 Apr 5–9; San Diego, CA. American Association for Cancer Research, Philadelphia, PA.
- Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics