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.

The presence of Estrogen Receptor β modulates the response of breast cancer cells to therapeutic agents

“…Apoptosis was measured fluorimetrically by using Annexin V method, as described previously (Fiorini et al, 2015). Briefly, MCF-7, MCF-7+ER␤, T47D or T47D-ER␤ cells were seeded in 96-well plates and treated with cytotoxic treatments.…”

Chemoresistance in pancreatic cancer: Emerging concepts

“…Gemcitabine stabilizes the expression of mutant p53 and the corresponding downstream targets cyclin-dependent kinase 1 and cyclin B1, resulting in hyperproliferation and chemoresistance (9) thus, mutant p53 contributes to gemcitabine resistance. The concomitant treatment of gemcitabine with the p53-reactivating molecules CP-31398 and recombining binding protein suppressor of hairless-interacting and tubulin associated protein resulted in an increased level of apoptosis and reduced growth rates (9). Hypoxia is another critical factor in tumor development and chemoresistance.…”

The Emerging Genetic Basis and Its Clinical Implication in Pancreatic Cancer

“…KRAS also induces PEAK1 amplification and desensitizing cancer cells to trastuzumab and gemcitabine [17]. Gemcitabine stabilized mutant p53 protein in the nuclei and induced chemoresistance [16]. KRAS knockdown abolished the insulin-like growth factor-1-induced ERK pathway in KRAS -mutated cancer cells and enhanced the therapeutic efficacy of everolimus [100].…”

“…An interplay between the N-terminus domain of secreted protein and rich in cysteine (SPARC), BCL2 and CASPASE-8 helps to augment apoptosis and consequently increase the response to treatment [105]. Combination treatment of gemcitabine and p53-reactivating molecules (CP-31398 and RITA) inhibits the proliferation of pancreatic cancer cells and induced apoptosis [16]. The inhibition of poly(adenosine diphosphate-ribose) polymerase (PARP) might be a potential synthetic lethal therapeutic strategy for the treatment of cancers with specific DNA repair defects, including carriers with BRCA1 or BRCA2 mutation [106].…”

“…In particular, several key gene mutations were found in a majority of familial pancreatic cancer (FPC) cases. Additionally, novel genetic studies indicated that mutated KRAS and p53 are involved in inherited or acquired drug resistance, including gemcitabine treatment [14,15,16,17]. …”