Novel nuclear localization of multidrug resistance associated protein 4 (MRP4/ABCC4) in human cancer cell lines

NATALIA GÓMEZ; JULIETA IMPERIALE; RODRIGO LAGOS; SAMANTA GANCEDO; CARLOS DAVIO; ANA SAHORES; BETINA GONZALEZ; CAROLINA GHANEM

Mar del Plata

Congreso; LXIV Reunión Científica anual de la Sociedad Argentina de Investigación Clínica; 2019

SAIC

The member of ATP Binding Cassette (ABC) family, MRP4 is responsible for substance extrusion, including cAMP, and is typically located in the plasma membrane. MRP4 is overexpressed in pancreatic and hepatocellular cancers, high levels of MRP4 tend to correlate with poor overall survival in patients with pancreatic ductal adenocarcinoma (PDAC). Preliminary results have shown a strong nuclear MRP4 staining in PDAC tumors. Thus, the aim of this study was to determine the novel presence of MRP4 in the nuclei of human PDAC and hepatocellular cancer cell lines. Therefore, MRP4 western blot (WB) assays were performed using enriched nuclei, total membrane and cytosolic isolated fractions (50µg/lane) obtained by ultracentrifugation of pancreatic BxPC-3 and hepatocellular HepG2 cancer cells. The enrichment was evaluated by histone, actin and GAPDH detection, respectively. Also, immunofluorescent colocalization of MRP4, GAPDH and DAPI was assessed in individual cells and isolated nuclear fraction by confocal microscopy. Our results show that MRP4 localizes in the nuclear fraction of both cancer cell lines, as the nuclear/total ratio was 1.3 in BxPC-3 cells and 0.3 in HepG2 cells. Total MRP4 expression in BxPC-3 cells doubles that of HepG2 cells (p