title: Mutant p53 stimulates chemoresistance of pancreatic adenocarcinoma cells to gemcitabine.
abstract: Pancreatic adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths worldwide; PDAC is characterized by poor prognosis, resistance to conventional chemotherapy and high mortality rate. TP53 tumor suppressor gene is frequently mutated in PDAC, resulting in the accumulation of mutated protein with potential gain-of-function (GOF) activities, such as genomic instability, hyperproliferation and chemoresistance. The purpose of this study was to assess the relevance of the p53 status on the PDAC cells response to the standard drug gemcitabine. We also examined the potential therapeutic effect of p53-reactivating molecules to restore the mutant p53 function in GEM treated PDAC cells. We showed that gemcitabine stabilized mutant p53 protein in the nuclei and induced chemoresistance, concurrent with the mutant p53-dependent expression of Cdk1 and CCNB1 genes, resulting in a hyperproliferation effect. Despite the adverse activation of mutant p53 by gemcitabine, simultaneous treatment of PDAC cells with gemcitabine and p53-reactivating molecules (CP-31398 and RITA) reduced growth rate and induced apoptosis. This synergistic effect was observed in both wild-type and mutant p53 cell lines and was absent in p53-null cells. The combination drug treatment induced p53 phosphorylation on Ser15, apoptosis and autophagosome formation. Furthermore, pharmacological inhibition of autophagy further increased apoptosis stimulated by gemcitabine/CP-31398 treatment. Together, our results show that gemcitabine aberrantly stimulates mutant p53 activity in PDAC cells identifying key processes with potential for therapeutic targeting. Our data also support an anti-tumoral strategy based on inhibition of autophagy combined with p53 activation and standard chemotherapy for both wild-type and mutant p53 expressing PDACs.
authors.affiliation: Department of Life and Reproduction Sciences, Biochemistry Section, University of Verona, Verona, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fiorini
authors.affiliation: Department of Life and Reproduction Sciences, Biochemistry Section, University of Verona, Verona, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cordani
authors.affiliation: Department of Life and Reproduction Sciences, Biochemistry Section, University of Verona, Verona, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Padroni
authors.affiliation: Translational Oncogenomic Unit, Regina Elena National Cancer Institute-IFO, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Blandino
authors.affiliation: Translational Oncogenomic Unit, Regina Elena National Cancer Institute-IFO, Rome, Italy. Electronic address: diagostino@ifo.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Di Agostino
authors.affiliation: Department of Life and Reproduction Sciences, Biochemistry Section, University of Verona, Verona, Italy. Electronic address: massimo.donadelli@univr.it.
authors.forename: Massimo
authors.initials: M
authors.lastname: Donadelli
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000235:genetics; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D006801:Humans; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics; D010766:Phosphorylation; D011743:Pyrimidines / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D011743:Pyrimidines; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D003841:Deoxycytidine; C402665:CP 31398; D000093542:Gemcitabine
keywords: Autophagy; Gain-of-function (GOF); Gemcitabine; Mutant p53; Pancreatic adenocarcinoma; p53-reactivating molecules