Armas-López, LeonelPiña-Sánchez, PatriciaArrieta, Oscarde Alba, Enrique GuzmanOrtiz-Quintero, BlancaSantillán-Doherty, PatricioChristiani, DavidZúñiga, JoaquínÁvila-Moreno, Federico2017-12-062017Armas-López, Leonel, Patricia Piña-Sánchez, Oscar Arrieta, Enrique Guzman de Alba, Blanca Ortiz-Quintero, Patricio Santillán-Doherty, David C. Christiani, Joaquín Zúñiga, and Federico Ávila-Moreno. 2017. “Epigenomic study identifies a novel mesenchyme homeobox2-GLI1 transcription axis involved in cancer drug resistance, overall survival and therapy prognosis in lung cancer patients.” Oncotarget 8 (40): 67056-67081. doi:10.18632/oncotarget.17715. http://dx.doi.org/10.18632/oncotarget.17715.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34492439Several homeobox-related gene (HOX) transcription factors such as mesenchyme HOX-2 (MEOX2) have previously been associated with cancer drug resistance, malignant progression and/or clinical prognostic responses in lung cancer patients; however, the mechanisms involved in these responses have yet to be elucidated. Here, an epigenomic strategy was implemented to identify novel MEOX2 gene promoter transcription targets and propose a new molecular mechanism underlying lung cancer drug resistance and poor clinical prognosis. Chromatin immunoprecipitation (ChIP) assays derived from non-small cell lung carcinomas (NSCLC) hybridized on gene promoter tiling arrays and bioinformatics analyses were performed, and quantitative, functional and clinical validation were also carried out. We statistically identified a common profile consisting of 78 gene promoter targets, including Hedgehog-GLI1 gene promoter sequences (FDR≤0.1 and FDR≤0.2). The GLI-1 gene promoter region from −2,192 to −109 was occupied by MEOX2, accompanied by transcriptionally active RNA Pol II and was epigenetically linked to the active histones H3K27Ac and H3K4me3; these associations were quantitatively validated. Moreover, siRNA genetic silencing assays identified a MEOX2-GLI1 axis involved in cellular cytotoxic resistance to cisplatinum in a dose-dependent manner, as well as cellular migration and proliferation. Finally, Kaplan-Maier survival analyses identified significant MEOX2-dependent GLI-1 protein expression associated with clinical progression and poorer overall survival using an independent cohort of NSCLC patients undergoing platinum-based oncological therapy with both epidermal growth factor receptor (EGFR)-non-mutated and EGFR-mutated status. In conclusion, this is the first study to investigate epigenome-wide MEOX2-transcription factor occupation identifying a novel overexpressed MEOX2-GLI1 axis and its clinical association with platinum-based cancer drug resistance and EGFR-tyrosine kinase inhibitor (TKI)-based therapy responses in NSCLC patients.en-USlung cancerhomeobox transcription factorsepigenetics cancer drug resistanceoverall survivaltreatment prognosisJournal Article2017-12-0610.18632/oncotarget.17715