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Treatment-induced tumor dormancy through YAP-mediated transcriptional reprogramming of the apoptotic pathway [YAP1 KO vs CTRL]

ABSTRACT: Eradicating tumor dormancy that develops following oncogene-targeted therapy, including after epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment of EGFR-mutant non-small cell lung cancer (NSCLC), is an attractive therapeutic strategy but the mechanisms governing the establishment of tumor dormancy are poorly understood. We observe that blockade of ERK1/2 reactivation following EGFR TKI treatment by combined EGFR/MEK inhibition uncovers cells that survive by entering a senescence-like dormant state, characterized by extensive epigenetic remodeling and high YAP/TEAD activity. YAP/TEAD trigger an epithelial-to-mesenchymal transition (EMT) program and engage the EMT transcription factor SLUG to directly repress pro-apoptotic BMF, limiting drug-induced apoptosis. Pharmacological co-inhibition of YAP or TEAD, or genetic deletion of YAP1, all deplete dormant cells by enhancing EGFR/MEK induced apoptosis. Thus, YAP activation can promote the survival of EGFR-mutant NSCLC cells in the chronic absence of EGFR signaling. Eradicating this population enhances the efficacy of targeted therapies which could ultimately lead to prolonged treatment responses in cancer patients.

ORGANISM(S): Homo sapiens

PROVIDER: GSE131601 | GEO | 2020/01/13

REPOSITORIES: GEO

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Project description:Regulation of organ size is important for development and tissue homeostasis. In Drosophila, Hippo signaling controls organ size by regulating the activity of a TEAD transcription factor, Scalloped, through modulation of its coactivator protein Yki. The role of mammalian Tead proteins in growth regulation, however, remains unknown. Here we examined the role of mouse Tead proteins in growth regulation. In NIH3T3 cells, cell density and Hippo signaling regulated the activity of Tead proteins by modulating nuclear localization of a Yki homologue, Yap, and the resulting change in Tead activity altered cell proliferation. Tead2-VP16 mimicked Yap overexpression, including increased cell proliferation, reduced cell death, promotion of EMT, lack of cell contact inhibition, and promotion of tumor formation. Growth promoting activities of various Yap mutants correlated with their Tead-coactivator activities. Tead2-VP16 and Yap regulated largely overlapping sets of genes. However, only a few of the Tead/Yapregulated genes in NIH3T3 cells were affected in Tead1-/-;Tead2-/- or Yap-/- embryos. Most of the previously identified Yap-regulated genes were not affected in NIH3T3 cells or mutant mice. In embryos, levels of nuclear Yap and Tead1 varied depending on cell types. Strong nuclear accumulation of Yap and Tead1 were seen in myocardium, correlating with requirements of Tead1 for proliferation. However, their distribution did not always correlate with proliferation. Taken together, mammalian Tead proteins regulate cell proliferation and contact inhibition as a transcriptional mediator of Hippo signaling, but the mechanisms by which Tead/Yap regulate cell proliferation differ depending on cell types, and Tead, Yap and Hippo signaling may play multiple roles in mouse embryos. We used microarrays to know the gene expression profiles regurated by Tead2-VP16, Tead2-EnR, Yap, and cell density in NIH3T3 cells. Keywords: Cell density, genetic modification Tead2-VP16-, Tead2-EnR-, Yap- and control vector-expressing cells were cultured at low or high density for RNA extraction and hybridization on Affymetrix microarrays.

Project description:Introduction: The clinical benefit of EGFR tyrosine kinase inhibitor (TKI) treatment in non-small cell lung cancer (NSCLC) patients with activating EGFR mutations is temporary, as virtually all patients develop acquired EGFR TKI resistance that occurs via diverse mechanisms. Here, we identified increased FGFR1 expression as such a resistance mechanism and using pathways analysis and drug combination testing we identified a novel combination treatment to control growth of these resistant tumors. Methods: Novel erlotinib-resistant NSCLC cell lines were generated and analyzed by mass spectrometry-based proteomics to identify altered pathways associated with erlotinib resistance. The altered pathways were further analyzed in gefitinib and osibenib resistant cell lines. Small molecule inhibitor combinations were used to block the altered pathways and investigate growth reduction in vitro and in two xenograft mouse models. FGFR1 mRNA levels were examined in pre- and (post?)- EGFR TKI treatment clinical tumor samples. Results: Proteomic analysis revealed increased expression of FGFR1 and AXL as well as increased Akt and ERK1/2 activation in a panel of novel erlotinib-resistant HCC827 cell lines. Combined treatment with erlotinib or osimertinib and a panel of small molecule inhibitors targeting AXL/MET, FGFRs, Akt, PI3K/mTOR, MEK or ERK1/2 showed that the most prominent re-sensitization to EGFR TKI occurred with the pan-FGFR inhibitor, PD173074. Interestingly, simultaneous blockade of components of the Akt pathway using specific Akt or dual PI3K-mTOR inhibitors combined with inhibitors targeting the FGFR family exhibited the most efficient growth inhibition of FGFR1 overexpressing EGFR TKI-resistant cell lines. Phosphorylation of proteins downstream of Akt, including PRAS40, FOXO and S6 ribosomal protein, were completely abrogated by PD173074 combined with the Akt inhibitor GSK2141795 . Combination treatment with PD173074 and an Akt inhibitor exhibited synergistic growth inhibition in vivo in two FGFR1 overexpressing NSCLC EGFR TKI-resistant animal models. Conclusion: The significant growth inhibition in vitro and in vivo observed with PD173074 combined with Akt compared to either drug alone imply that inhibition of several key targets may be beneficial in controlling erlotinib-resistant NSCLC. The complete abrogation of PRAS40, FOXO and S6 phosphorylations by PD173074 combined with an Akt inhibitor indicates that the Akt pathway is no longer active.

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Treatment-induced tumor dormancy through YAP-mediated transcriptional reprogramming of the apoptotic pathway [YAP1 KO vs CTRL]

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