Project description: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. reference x sample

Project description: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.

Project description:The TBX2 transcription factor plays critical roles during embryonic development and it is overexpressed in several cancers, where it contributes to key oncogenic processes including the promotion of proliferation and bypass of senescence. Importantly, based on compelling biological evidences, TBX2 has been considered as a potential target for new anticancer therapies. There has therefore been a substantial interest to identify molecules with TBX2-modulatory activity, but no such substance has been found to date. Here, we adopt a targeted approach based on a reverse-affinity procedure to identify the ability of chromomycins A5 (CA5) and A6 (CA6) to interact with TBX2. Briefly, a TBX2-DNA-binding domain recombinant protein was N-terminally linked to a resin, which in turn, was incubated with either CA5 or CA6. After elution, bound material was analyzed by UPLC-MS and CA5 was recovered from TBX2-loaded resins. To confirm and quantify the affinity (KD) between the compounds and TBX2, microscale thermophoresis analysis was performed. CA5 and CA6 modified the thermophoretic behavior of TBX2, with a KD in micromolar range. To begin to understand whether these compounds exerted their anti-cancer activity through binding TBX2, we next analyzed their cytotoxicity in TBX2 expressing breast carcinoma, melanoma and rhabdomyosarcoma cells. The results show that CA5 was consistently more potent than CA6 in all tested cell lines with IC50 values in the nM range. Of the cancer cell types tested, the melanoma cells were most sensitive. The knockdown of TBX2 in 501mel melanoma cells increased their sensitivity to CA5 by up to 5 times. Furthermore, inducible expression of TBX2 in 501mel cells genetically engineered to express TBX2 in the presence of doxycycline, were less sensitive to CA5 than the control cells. Together, the data presented in this study suggest that, in addition to its already recognized DNA-binding properties, CA5 may be binding the transcription factor TBX2, and it can contribute to its cytotoxic activity.

Dataset Information

Novel role of Engrailed 1 as a prosurvival transcription factor in basal-like breast cancer and engineering of interference peptides block its oncogenic function.

Publications

Novel role of Engrailed 1 as a prosurvival transcription factor in basal-like breast cancer and engineering of interference peptides block its oncogenic function.

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