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

FRANCISCO DAMIÁN ROSA; MARÍA CECILIA LIRA; LAURA PANELO; MILENI MACHADO; MÓNICA ALEJANDRA COSTAS; MARÍA FERNANDA RUBIO

Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

SAIC

It has been reported that some chemotherapeutics induce immunogeniccell death (ICD). ICD is characterized by alterations in theplasmatic membrane and the microenvironment of the dying cell.Autophagy is a process that precedes ICD as it allows such changeslike ATP exocytosis and avoid the up regulation of the immunosuppresssiveecto-ATPase CD39.Our group has previously shown that the down regulation of RAC3expression in HCT 116 colon adenocarcinoma cell line sensitizesto 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 thesedrugs stimulate autophagy in HCT 116 and in this cell line transfectedwith a short hairpin RNA against RAC3 (shRAC3); and if thismechanism could lead to ICD.Autophagy was assayed by Western blot against LC3. After 24 hpost 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 inducedautophagy could lead to ICD, the cell lines were pretreated with TSA(0.4 mM) and then stimulated with the drugs to performed an immunofluorescenceagainst acetylated proteins. Compared with HCTcontrol (87±11), the acetylation percentage decreased in shRAC3cell line (37±8 p