Niechi, IgnacioErices, José I.Carrillo-Beltrán, DiegoUribe-Ojeda, AteneaTorres, ÁngeloRocha, José DellisUribe, DanielToro, María A.Villalobos-Nova, KarlaGaete-Ramírez, BelénMingo, GabrielOwen, Gareth I.Varas-Godoy, ManuelJara, LilianAguayo, FranciscoBurzio, Verónica A.Quezada-Monrás, ClaudiaTapia, Julio C.2024-09-052024-09-052023-02Cells. Volume 12, Issue 3. February 2023. Article number 5062073-4409https://repositorio.unab.cl/handle/ria/59871Indexación: Scopus.This work was supported by Vicerrectoría de Investigación y Desarrollo de la Universidad de Chile VID ENL10/21 (J.C.T); Líneas de apoyo a la investigación financiadas por el ICBM 2021 (J.C.T.); ANID/BASAL/FB210008 (M.V.G. and V.A.B.); DI-05-20/REG UNAB (V.A.B.); Vicerrectoría de Investigación, Desarrollo y Creación artística (VIDCA) de la Universidad Austral de Chile (C.Q.-M.); ANID/IMII, ICN09-016/ICN 2021-045 (C.Q.-M. and G.I.O.); ANID/FONDAP-ACCDIS 1513001 (G.I.O. and M.V.-G.); and ANID/FONDECYT grants 11220149 (I.N.), 1200049 (L.J.), 1190928 (M.V.G.), 1221033 (F.A.), 1200885 (C.Q.M.), 1220586 (G.I.O.), 3220237 (D.C.-B) and 1220353 (J.C.T.).Glioblastoma (GBM) is the most common and aggressive type of brain tumor due to its elevated recurrence following treatments. This is mainly mediated by a subpopulation of cells with stemness traits termed glioblastoma stem-like cells (GSCs), which are extremely resistant to anti-neoplastic drugs. Thus, an advancement in the understanding of the molecular processes underlying GSC occurrence should contribute significantly towards progress in reducing aggressiveness. High levels of endothelin-converting enzyme-1 (ECE1), key for endothelin-1 (ET-1) peptide activation, have been linked to the malignant progression of GBM. There are four known isoforms of ECE1 that activate ET-1, which only differ in their cytoplasmic N-terminal sequences. Isoform ECE1c is phosphorylated at Ser-18 and Ser-20 by protein kinase CK2, which increases its stability and hence promotes aggressiveness traits in colon cancer cells. In order to study whether ECE1c exerts a malignant effect in GBM, we designed an ECE1c mutant by switching a putative ubiquitination lysine proximal to the phospho-serines Lys-6-to-Arg (i.e., K6R). This ECE1cK6R mutant was stably expressed in U87MG, T98G, and U251 GBM cells, and their behavior was compared to either mock or wild-type ECE1c-expressing clone cells. ECE1cK6R behaved as a highly stable protein in all cell lines, and its expression promoted self-renewal and the enrichment of a stem-like population characterized by enhanced neurospheroid formation, as well as increased expression of stem-like surface markers. These ECE1cK6R-derived GSC-like cells also displayed enhanced resistance to the GBM-related chemotherapy drugs temozolomide and gemcitabine and increased expression of the ABCG2 efflux pump. In addition, ECE1cK6R cells displayed enhanced metastasis-associated traits, such as the modulation of adhesion and the enhancement of cell migration and invasion. In conclusion, the acquisition of a GSC-like phenotype, together with heightened chemoresistance and invasiveness traits, allows us to suggest phospho-ECE1c as a novel marker for poor prognosis as well as a potential therapeutic target for GBM. © 2023 by the authors.enAggressivenessCK2EndothelinGlioblastomaStemnessArtículoCC BY 4.0 Attribution 4.0 International Deed10.3390/cells12030506