? Thyroid hormones effects inbexarotene treatment of breast cáncer cells.

CINTHIA ROSEMBLIT; STERLE, H.A.; DÍAZ FLAQUÉ, M.C.; DIAZ ALBUJA, JOHANNA; CAYROL, FLORENCIA; CREMASCHI, G.A.; DEBERNARDI, M; PAULAZO, M.A.

Congreso; REUNIÓN ANUAL DE SOCIEDADES DE BIOCIENCIA 2019; 2019

Chemoresistance is a major cause ofcancer treatment failure. Many breast cancer (BC) cells developchemoresistance by diminishing intracellular drug accumulation,upregulating protein levels or activating transporters like MDR1.Previously we demonstrated that thyroid hormones (THs)modulate chemotherapy response in T cell lymphoma (TCL) cells.However, in BC cells little is known about these mechanisms thatlead to tumor chemotherapy resistance and are crucial to assurethe success of treatment. Bexarotene (Bex) is an oral retinoid-X-receptor agonist that is effective for the treatment of early andadvanced-stage in cutaneous TCL and there are ongoing clinicaltrials to determine its role in both BC treatment and prevention.However thyroid dysfunction is recognized as an important sideeffect of such therapies, potentially manageable by THsadministration. To study how THs affect MDA-MB-231 drugtransport, rhodamine 123 (RHO123) incorporation assay wasperformed. Our results shown that MDA-MB-231 cells incorporateRHO123 in a time dependent manner, reaching to a plateau at 3h, and this effect was not affected by THs treatment. On theother hand, we found that THs increase RHO123 exclusion at 1 hin BC cells (p