Oncotarget

Research Papers:

AMPK and PKA interaction in the regulation of survival of liver cancer cells subjected to glucose starvation

Anabela C. Ferretti, Facundo M. Tonucci, Florencia Hidalgo, Evangelina Almada, Maria C. Larocca and Cristián Favre _

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Oncotarget. 2016; 7:17815-17828. https://doi.org/10.18632/oncotarget.7404

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Abstract

Anabela C. Ferretti1, Facundo M. Tonucci1, Florencia Hidalgo1, Evangelina Almada1, Maria C. Larocca1, Cristián Favre1

1Institute of Experimental Physiology, CONICET, School of Biochemical Sciences, University of Rosario, Rosario, Argentina

Correspondence to:

Cristián Favre, e-mail: cfavre@unr.edu.ar, favre@ifise-conicet.gov.ar

Keywords: AMPK, apoptosis, cancer cell killing, hepatocellular carcinoma, signaling

Received: August 31, 2015    Accepted: January 29, 2016    Published: February 15, 2016

ABSTRACT

The signaling pathways that govern survival response in hepatic cancer cells subjected to nutritional restriction have not been clarified yet. In this study we showed that liver cancer cells undergoing glucose deprivation both arrested in G0/G1 and died mainly by apoptosis. Treatment with the AMPK activator AICAR phenocopied the effect of glucose deprivation on cell survival, whereas AMPK silencing in HepG2/C3A, HuH-7 or SK-Hep-1 cells blocked the cell cycle arrest and the increase in apoptotic death induced by glucose starvation. Both AMPK and PKA were promptly activated after glucose withdrawal. PKA signaling had a dual role during glucose starvation: whereas it elicited an early decreased in cell viability, it later improved this parameter. We detected AMPK phosphorylation (AMPKα(Ser173)) by PKA, which was increased in glucose starved cells and was associated with diminution of AMPK activation. To better explore this inhibitory effect, we constructed a hepatocarcinoma derived cell line which stably expressed an AMPK mutant lacking that PKA phosphorylation site: AMPKα1(S173C). Expression of this mutant significantly decreased viability in cells undergoing glucose starvation. Furthermore, after 36 h of glucose deprivation, the index of AMPKα1(S173C) apoptotic cells doubled the apoptotic index observed in control cells. Two main remarks arise: 1. AMPK is the central signaling kinase in the scenario of cell cycle arrest and death induced by glucose starvation in hepatic cancer cells; 2. PKA phosphorylation of Ser173 comes out as a strong control point that limits the antitumor effects of AMPK in this situation.


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