Englerin A Stimulates PKCθ to Inhibit Insulin Signaling and to Simultaneously Activate HSF1: Pharmacologically Induced Synthetic Lethality

The natural product englerin A (EA) binds to and activates protein kinase C-theta (PKC theta). EA-dependent activation of PKC theta induces an insulin-resistant phenotype, limiting the access of tumor cells to glucose. At the same time, EA causes PKC theta-mediated phosphorylation and activation of the transcription factor heat shock factor 1, an inducer of glucose dependence. By promoting glucose addiction, while simultaneously starving cells of glucose, EA proves to be synthetically lethal to highly glycolytic tumors.