A novel Nupr1-Aurora kinase A pathway provides protection against metabolic stress-mediated autophagic-associated cell death

Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. In this work we demonstrated that both Nupr1 and HIF1alpha are co-expressed in human PDAC samples and negatively correlate with survival time and therefore could be used as prognosis markers. In addition, we also demonstrated that PDAC cells become resistant to the metabolic stress by activating an efficient intracellular defense pathway involving a Nupr1-dependent AURKA activation pathway. These findings pointed at a strong protumoral function of AURKA and, in consequence, at a potential efficacy of inhibitors of AURKA to treat cancers. Such rationale was based on AURKA effect on mitosis and data from our study provide an additional argument for its targeting. We suggest that inhibition of AURKA will sensitize preferentially intrapancreatic tumor cells located near hypovascularized regions, which should correspond to the most resistant cells because they have been selected by exposure to an adverse microenvironment, and also to the areas of the tumor in which the anticancer drugs results are less accessible. Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Abstract Purpose: The limited supply of oxygen and nutrients is thought to result in rigorous selection of cells that will eventually form the tumor. Experimental design: Nupr1 expression pattern was analyzed in human TMA and correlated with patient's survival time. Microarray analysis was performed on MiaPaCa2 cells subjected to metabolic stress in Nupr1 silenced conditions. DNA repair and cell cycle associated genes expression was confirmed by RT-qPCR. Nupr1 and AURKA protective role were analyzed using RNAi silencing or overexpression. DNA damage and autophagy were analyzed by western blot and immunofluorescence. Results: We demonstrated that both Nupr1 and HIF1alpha are co-expressed in human PDAC samples and negatively correlate with survival time. PDAC-derived cells submitted to hypoxia and/or glucose starvation induce DNA damage-dependent cell death concomitantly to the overexpression of stress protein Nupr1. Affymetrix-based transcriptoma analysis reveals that Nupr1 knockdown enhances DNA damage and alters the expression of several genes involved in DNA repair and cell cycle progression. Expression of some of these genes is common to hypoxia and glucose starvation such as Aurka gene, suggesting that Nupr1 overexpression counteracts the transcriptional changes occurring under metabolic stress. The molecular mechanism by which hypoxia and glucose starvation induce cell death involves autophagy-associated, but not caspase-dependent, cell death. Finally, we have found that AURKA expression is partially regulated …