Anales de la RANM

44 A N A L E S R A N M R E V I S T A F U N D A D A E N 1 8 7 9 S U P L E M E N T O I SIMPOSIO · JÓVENES INVESTIGADORES Libro de Abstracts An RANM. 2021;138(03).supl01: 44 - 54 constituir una buena estrategia para revertir la resistencia en tumores TNBC resistentes, como tratamiento único o en combinación con otros quimioterápicos. Background: Triple negative breast cancer (TNBC) is the most heterogeneous breast cancer subtype due largely to a high presence of tumor stem cells (CSCs). Moreover, this tumor subtype has no specific therapeutic targets, which restricts its treatment to traditional radiotherapy and chemotherapy. These treatments largely affect normal tumor cells, but CSCs often show intrinsic resistance to these treatments. For this reason, this cell population is increased as tumors become resistant to treatment. BET proteins are epigenetic effectors known to control the expression of CSC markers, and therefore BET inhibitors (BETi), such as JQ1, could be a treatment alternative that controls the CSC population within the tumor and helps reverse chemoresistance. As occurs in parental lines according to previously published data in the laboratory, where JQ1 manages to reduce these markers and therefore, this population is reduced. Materials and methods: For this work, cellular models of resistance to traditional chemotherapy were generated in TNBC cells. Through qPCR studies, the expression of a panel of CSC markers in the generated cells was analyzed by comparing them with the sensitive lines and the impact of JQ1 on these markers was evaluated. MTT proliferation, tumor progression and tumor initiation assays, through colony formation, were also performed on resistant cells in response to this BETi. The response to this inhibitor on apoptosis of the resistant cell population was assessed by flow cytometry analysis of Annexin V binding. Results: TNBC cells with acquired resistance to chemotherapy showed increased expression of CSC markers. Treating the cells with JQ1 reduced the expression of these markers, although they were increased in the resistant model. In addition, these drugs slowed cell proliferation and hindered tumor progression of chemotherapy-resistant cells, also preventing colony formation, which translates into a reduction in the relapse of these tumors after treatment. Apoptosis assessment confirmed that BETi caused cell death in these models. All these results have been studied in comparison with the sensitive line, where no reduction of these studied properties can be observed. Conclusions: BET inhibitors decrease CSCs markers in TNBC, which is better achieved in the resistant model, despite their overexpression, and reduce CSCs properties (proliferation, progres- sion, and tumor initiation). Therefore, it could be a good strategy to reverse resistance in resistant TNBC tumors, as a single treatment or in combina- tion with another chemotherapeutics. Introducción: El glioblastoma multiforme (GBM) es un tumor cerebral muy agresivo y para el que no existe un tratamiento eficaz. Actualmente, es el tumor cerebral más frecuente y la mediana de supervivencia es de 15 meses desde su diagnóstico. La resección quirúrgica completa es complicada, ya que son muy invasivos y suelen infiltrarse. El tratamiento habitual es la quimioterapia alquilante con temozolamida (TMZ). El 15% de los pacientes desarrollan resistencia adquirida al tratamiento estándar. Se ha identificado una nueva población celular, las células iniciadoras del glioma (GICs), que son similares a las Cancer Stem Cells (CSCs). Las GICs muestran resistencia a las terapias estándar y son las principales responsables de la recurrencia. Por otro lado, las proteínas BET están implicadas en la transcripción, el ciclo celular o la inflamación y se relacionan con proteínas oncogénicas implicadas en el desarrollo de cáncer. Se ha demostrado que algunos inhibidores de proteínas BET son capaces de potenciar la actividad de la TMZ en GBM. Además, en trabajos previos del laboratorio se ha usado el inhibidor epigenético JQ1 en modelos 3D ricos en CSCs, ya que es capaz de inhibir algunos factores de transcripción implicados en ciclo celular, proliferación y metástasis. A su vez, ha demostrado un mayor efecto en los modelos más resistentes, coincidiendo con un elevado número de CSCs. El objetivo de este trabajo será la evaluación de terapias alternativas que consigan evitar o combatir la resistencia adquirida a las terapias actuales producidas por las GICs. Métodos: Se usaron las líneas celulares adherentes A172, T98, U87 y U118, así como los modelos 3D derivados de pacientes, GH2 y 12O12, los cuales, son ricos en GICs. Se llevaron a cabo ensayos de MTT, citometría de flujo y cristal violeta para evaluar la viabilidad celular en los modelos 2D tras la combinación de los inhibidores epigenéticos con EL USO DE INHIBIDORES EPIGENÉTICOS POTEN- CIA EL EFECTO DE LA TEMOZOLAMIDA EN MO- DELOS 2D Y 3D DE GLIOBLASTOMA MULTIFORME THE USE OF EPIGENETIC INHIBITORS ENHANCES THE EFFECT OF TEMOZOLOMIDE IN 2D AND 3D MO- DELS OF GLIOBLASTOMA MULTIFORME Raquel López-Rosa 1,2 , David Tébar-García 1,2 , María del Mar Noblejas-López 1,2 , Miriam Nuncia-Cantarero 2 , Cristina Nieto-Jiménez 4 , Eva M. Galán-Moya 1,2,3 * 1 Translational Research Unit, Albacete University Hospital, Albacete, Spain. 2 Centro Regional de Investigaciones Biomédicas (CRIB), Uni- versidad de Castilla-La Mancha, Albacete, Spain. 3 Nursery faculty, Castilla-La Mancha University (UCLM), Al- bacete, Spain. 4 Experimental Therapeutics Unit, Medical Oncology Depart- ment, Hospital Clínico San Carlos (HCSC), Instituto de Investi- gación Sanitaria (IdISSC) and CIBERONC, Madrid, Spain.