Autophagy mediates resistance of pancreatic cancer cells to chemotherapy through a novel E2F1-P300-VMP1 pathway

VACCARO, MARIA I.1; ROPOLO, ALEJANDRO1; GIOVENCO, MARCELA1; CATRINACIO, CINTIA 1; RENNA, FELIPE1; GRASSO, DANIEL1; BOGGIO, VERONICA1

Washington

Congreso; Digestive Disease Week; 2015

American Gastroenterological Association

CONTROL ID: 2169190CURRENT CATEGORY: Pancreatic DisordersPRESENTATION TYPE: AGA Institute Oral or PosterPRESENTER: Maria VaccaroPRESENTER (E-MAIL ONLY): maria.vaccaro@gmail.comAbstractTITLE: Autophagy mediates resistance of pancreatic cancer cells to chemotherapy through a novel E2F1-P300-VMP1pathwayAUTHORS (LAST NAME, FIRST NAME): Vaccaro, Maria I.1; Ropolo, Alejandro1; Giovenco, Marcela1; Catrinacio,Cintia 1; Renna, Felipe1; Grasso, Daniel1; Boggio, Veronica1INSTITUTIONS (ALL):1. Institute of Biochemistry and Molecular Medicine, Pathophysiology Department, CONICET - University of BuenosAires, Buenos Aires, Argentina.ABSTRACT BODY:Abstract Body: Autophagy is an evolutionarily preserved degradation process of cytoplasmic cellular constituents,which participates in cell response to disease. We characterized VMP1 (Vacuole Membrane Protein 1) as an essentialautophagy related-protein that mediates autophagy in pancreatic diseases. VMP1 is induced by activated K-Ras andgemcitabine treatment in human pancreatic tumor cells. Moreover, VMP1 is over-expressed in poorly differentiatedhuman pancreatic cancer. Here we characterize a new molecular pathway, mediated by VMP1, by which gemcitabineis able to trigger autophagy in human pancreatic tumor cells. We demonstrated that gemcitabine requires VMP1expression to induce autophagy in highly resistant pancreatic cancer cells PANC-1 carrying activated K-Ras, but notin BxPC-3 cells that do not carry K-Ras mutation. Analysis of the mechanisms identified E2F1, a transcription factorthat is regulated by the retinoblastoma pathway, as an effector of gemcitabine-induced autophagy. E2F1 regulates theexpression and promoter activity of VMP1. Chromatin immunoprecipitation assays demonstrated that E2F1 binds tothe VMP1 promoter in PANC-1 cells. We also identified the histone acetyltransferase p300 as a modulator of thispromoter activity. Our data show that the E2F1-p300 activator/co-activator complex is part of the regulatory pathwaycontrolling the expression and promoter activity of VMP1 triggered by gemcitabine in PANC 1 cells. Finally,downregulation of VMP1 expression and pharmacological modulation of autophagy sensitize PANC-1 cells toapoptosis and diminish clonogenicity under gemcitabine treatment. Together, these data provide evidence of atranscriptional regulation mechanism of autophagy that integrates this cellular process into the complex network ofevents involved in PDAC chemoresistance.