Novel role of Engrailed 1 as pro-survival transcription factor in basal-like breast cancer and engineering of interference peptides to block its oncogenic function

ABSTRACT: Basal-like breast tumors are aggressive cancers associated with high proliferation and metastasis. Currently basal-like breast cancer patients can only be treated with chemotherapy options. However, resistance to chemotherapy often occurs, resulting in recurrence and patient death. Some extremely aggressive basal-like breast cancers are also associated with hypoxia, inflammation and high leukocyte infiltration. Herein we discovered that the neural-specific transcription factor Engrailed 1 (EN1) is exclusively overexpressed in basal-like breast cancers. ShRNA-mediated knockdown of EN1 in basal-like breast cancer cells triggered potent and selective cell death. In contrast, ectopic overexpression of EN1 in normal cells activated survival pathways and conferred resistance to chemotherapeutic agents. Exogenous expression of EN1 cDNA reprogrammed the breast epithelial cells towards a long-lived, neural-like phenotype displaying dopaminergic markers. Gene expression microarrays demonstrated that the EN1 cDNA altered transcription of a high number of inflammatory molecules, notably chemokines and chemokine receptors, which could mediate pro-survival pathways. To block EN1 function, we engineered synthetic interference peptides (iPeps) comprising the EN1-specific sequences mediating essential protein-protein interactions necessary for EN1 function and an N-terminal cell-penetrating peptide/nuclear localization sequence. These EN1-iPeps rapidly mediated a strong apoptotic response in tumor cells overexpressing EN1, with no toxicity to normal or non EN1-expressing cells. Delivery of EN1-iPeps into basal-like cancer cells significantly decreased the IC50 of chemotherapeutic drugs routinely used to treat breast cancer. Lastly, MALDI-TOF mass spectrometry and immunoprecipitation assays demonstrated that EN1-iPeps captured targets involved in transcriptional and post-transcriptional regulation. Importantly, the EN1-iPeps bound the Glutamyl-prolyl tRNA synthetase (EPRS) target, which has been associated with the transcript-specific translational control of inflammatory proteins and activation of amino acid stress pathways. These studies show that EN1 activates intrinsic inflammatory pathways associated with pro-survival in basal-like breast cancer and that peptides targeting EN1 function could potentially be used to combat these lethal forms of breast cancer.

ORGANISM(S): Homo sapiens

PROVIDER: GSE47358 | GEO | 2013/12/31

SECONDARY ACCESSION(S): PRJNA205301

REPOSITORIES: GEO