DOWN REGULATION OF RAC3 IN COLORECTAL CANCER SENSITIZES TO THE TREATMENT WITH 5-FLUOROURACIL AND OXALIPLATIN THROUGH AN INCREASE IN THE LEVELS OF AUTOPHAGY

LIRA, MARÍA CECILIA; COSTAS, MÓNICA A; ROSA, FRANCISCO D; SOARES MACHADO, MILENI; PANELO, LAURA C; RUBIO, MARÍA FERNANDA

Ciudad Autónoma de Buenos Aires

Congreso; LXII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2017

Sociedad Argentina de Investigación Clínica

It has been reported that some chemotherapeutics induce immunogenic cell death (ICD). ICD is characterized by alterations in the plasmatic membrane and the microenvironment of the dying cell. Autophagy is a process that precedes ICD as it allows such changes like ATP exocytosis and avoid the up regulation of the immunosuppresssive ecto-ATPase CD39. Our group has previously shown that the down regulation of RAC3 expression in HCT 116 colon adenocarcinoma cell line sensitizes to the treatment with 5-fluorouracil 3.5 mM (5Fu) and oxaliplatin 0.4mM (oxa), chemotherapeutics for colorectal cancer patients. In view, that RAC3 over expression inhibits autophagy; we analyzed if these drugs stimulate autophagy in HCT 116 and in this cell line transfected with a short hairpin RNA against RAC3 (shRAC3); and if this mechanism could lead to ICD. Autophagy was assayed by Western blot against LC3. After 24 h post treatments, both drugs increase the ratio of LC3II/I on shRAC3 (HCT control, 5Fu: 1.1, oxa: 1.0; shRAC3, basal: 1.0 5Fu: 1.3, oxa: 1.4-fold respect HCT control basal). Furthermore, to study if induced autophagy could lead to ICD, the cell lines were pretreated with TSA (0.4 mM) and then stimulated with the drugs to performed an immunofluorescence against acetylated proteins. Compared with HCTcontrol (87±11), the acetylation percentage decreased in shRAC3 cell line (37±8 p