Integrative bioinformatics and proteomics-based discovery of an eEF2K inhibitor (cefatrizine) with ER stress modulation in breast cancer cells

Eukaryotic elongation factor-2 kinase (eEF2K), a unique calcium/calmodulin-dependent protein kinase, is well known to regulate apoptosis, autophagy and ER stress in many types of human cancers. Therefore, eEF2K would be regarded as a promising therapeutic target; however, the eEF2K-regulated mechanism and its targeted inhibitor still remain to be discovered in cancer. Herein, we constructed a protein-protein interaction (PPI) network of eEF2K and achieved an eEF2K-regulated ER stress subnetwork by bioinformatics prediction. Then, we found that the differential protein expressions involved in ER stress in the context of si-eEF2K-treated MCF-7 and MDA-MB-436 cells by iTRAQ-based analyses, respectively. Integrated into these aforementioned results, we constructed a core eEF2K-regulated ER stress subnetwork in breast cancer cells. Subsequently, we screened a series of candidate compounds targeting eEF2K and discovered a novel eEF2K inhibitor (cefatrizine) with an anti-proliferative activity toward breast cancer cells. Moreover, we found that cefatrizine induced ER stress in both MCF-7 and MDA-MB-436 cells. Interestingly, we demonstrated that the mechanism of cefatrizine-induced ER stress was in good agreement with our bioinformatics and proteomics-based results. In conclusion, these results demonstrate that a novel eEF2K inhibitor (cefatrizine) induces ER stress in breast cancer cells by integrating bioinformatics prediction, proteomics analyses and experimental validation, which would provide a clue for exploring more mechanisms of eEF2K and its targeted inhibitors in cancer therapy.