CYCLOOXYGENASE-2 REGULATES THE SENSITIVITY OF LUNG ADENOCARCINOMA CELLS TO IONIZING RADIATION.

ACQUIER, A B; MENDEZ, C F; BLANCO, H A; PAZ, C; MORI SEQUEIROS GARCIA, M M

Buenos Aires

Congreso; 62º Reunión científica anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2017

Sociedad Argentina de Investigación Clínica (SAIC)

Radioresistance is defined as a cell?s capacity to surviveafter exposure to high energy radiation, a fact that may limit therapeuticoptions by reducing the efficacy of radiotherapy (Rt). Numeroustumor cells show a high expression of cyclooxygenase-2 (COX-2), a fact that has been linked to more aggresive tumor phenotypes.Also, the COX-2 inhibitor celecoxib (CXB) has been proposed as apossible Rt enhancer. We aim here to investigate whether COX-2activity and expression regulate radiosensibility in a radioresistantlung adenocarcinoma-derived cell line (A549). Cells were exposedto varying doses (0-10 Gy) of 60Co ionizing radiation (IR) in the presenceor the absence of 7.5 mM CXB and radiosensitivity was determinedusing a standard clonogenic assay, cell cycle was studied byflow cytometry after propidium iodide staining and MAPKs activationand COX-2 expression by western blot using specific antibodies.IR produced a significant and dose-dependent reduction of cellviability showing an a/b ratio of 14.2 when calculated using the linearquadratic model, an effect that was significantly (p