P-glycoprotein 1 mediates Galectin-1-induced resistance to doxorubicin in hepatocellular carcinoma cells.

CARABIAS, PABLO; BACIGALUPO, MARÍA L.; OTERO, SILVINA; SAFFIOTTI, NICOLÁS; ELOLA, MARÍA TERESA; WOLFENSTEIN-TODEL, CARLOTA; ROSSI, JUAN PABLO; RABINOVICH, GABRIEL A.; ESPELT, MARÍA V.; TRONCOSO, MARÍA F.

MAR DEL PLATA, PROVINCIA DE BUENOS AIRES

Congreso; LXI Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica,; 2016

SOCIEDAD ARGENTINA DE INVESTIGACION CLINICA

P-glycoprotein 1 mediates Galectin-1-induced resistance to doxorubicin in hepatocellular carcinoma cellsCarabias P*, Bacigalupo ML*, Otero S*, SaffiotiN*, Elola MT*, Wolfenstein C*, Rossi JP*, Rabinovich GA&, Espelt MV* y Troncoso MF*.* IQUIFIB, Facultad de Farmacia y Bioquímica, UBA.&IByME-CONICET.carabiaspablo@gmail.comGalectin-1 (Gal1), a β-galactoside-binding protein, is overexpressedin hepatocellular carcinoma (HCC) and it is related to tumor aggressiveness. P-glycoprotein 1 (Pgp) is an ATP-dependent drug efflux pump localized in hepatocyte canalicular membrane. Its overexpression in tumor cells decreases intracellular chemotherapeutic drug concentration, bestowing a multidrug resistant phenotype. Previously, we reported that Gal1 overexpression in HCC HepG2 cells (HepG2Gal1) reduces apoptosis induced by the chemotherapeutic drugs camptothecin and doxorubicin (DOX). Also, we described that HepG2Gal1 cells show increased levels of Pgp protein expression.The aim of this work was to determine if Gal1 overexpression reduces intracellular DOX levels in HepG2 cells. Moreover, we confirmedPgp involvement inGal1-mediated resistanceto DOX-induced deathin HepG2 cells.Byfluorescence techniques we found a significant decrease in intracellular DOX concentration (pmol/µM total protein) in HepG2Gal1 cells compared with HepG2 cells (1.2±0.1 vs 1.8±0.1, 30min after treatment; 1.7±0.4 vs 2.9±0.5, 60min; 2.3±0.5 vs 4.5±1, 90min; 3.1±0.7 vs 5.6±1.2, 120min).Co-incubation of HepG2 and HepG2Gal1 cells for 24h with DOX (2µM) and verapamil (20µM), a Pgpinhibitor, diminished cell viability (MTT) compared with cells incubated only with DOX (HepG2, 37.4±5.1% vs 54±5.3%; HepG2Gal1, 60.1±3.4% vs 77.8±2.5%).Similar results were obtained silencing Pgp expressionin HepG2Gal1 cells with specific siRNA (Scr+DOX 61.1±2.7% vssiRNA+DOX 40.8±7.2%). However, probenecid treatment (250µM), a multidrug resistance-associated protein 2 (MRP2) inhibitor, did not change DOX-treated cell viability (HepG2, 51.5±9.3% vs 53.1±6.7%; HepG2Gal1, 69.0±9.8% vs 78.1±12.3%).In conclusion, Gal1-overexpressing HepG2 cells accumulate less intracellular DOX, conferring a resistance phenotype. Moreover, Pgp activity inhibition, but not MRP2, or decreasing its expressionsensitizes HepG2 cells to DOX treatment, suggesting the involvement of Pgp in Gal1-induced resistance to DOX.