Induction of autophagy by ARHI (DIRAS3) alters fundamental metabolic pathways in ovarian cancer models

BMC Cancer

Research Article

Brian J. Engel¹  Joshua Gray¹  Pratip K. Bhattacharya¹  Lindsay E. Kelderhouse¹  Argentina Ornelas¹  Christopher R. McCullough¹  Niki M. Zacharias²  Steven W. Millward²  Hailing Yang³  Yan Wang³  Robert C. Bast³  Weiqun Mao³  Margie N. Sutton³  Zhen Lu³ 

[1] Department of Cancer Systems Imaging, the University of Texas M.D. Anderson Cancer Center, Houston, USA;Department of Cancer Systems Imaging, the University of Texas M.D. Anderson Cancer Center, Houston, USA;Department of Bioengineering, Rice University, Houston, USA;Department of Experimental Therapeutics, the University of Texas M.D. Anderson Cancer Center, Houston, USA;

关键词: ARHI;    Autophagy;    Metabolism;    Glutaminolysis;    Ovarian cancer;    NMR;    Necroptosis;   

DOI  :  10.1186/s12885-016-2850-8

 received in 2015-08-17, accepted in 2016-10-10,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundAutophagy is a bulk catabolic process that modulates tumorigenesis, therapeutic resistance, and dormancy. The tumor suppressor ARHI (DIRAS3) is a potent inducer of autophagy and its expression results in necroptotic cell death in vitro and tumor dormancy in vivo. ARHI is down-regulated or lost in over 60 % of primary ovarian tumors yet is dramatically up-regulated in metastatic disease. The metabolic changes that occur during ARHI induction and their role in modulating death and dormancy are unknown.MethodsWe employed Nuclear Magnetic Resonance (NMR)-based metabolomic strategies to characterize changes in key metabolic pathways in both cell culture and xenograft models of ARHI expression and autophagy. These pathways were further interrogated by cell-based immunofluorescence imaging, tracer uptake studies, targeted metabolic inhibition, and in vivo PET/CT imaging.ResultsInduction of ARHI in cell culture models resulted in an autophagy-dependent increase in lactate production along with increased glucose uptake and enhanced sensitivity to glycolytic inhibitors. Increased uptake of glutamine was also dependent on autophagy and dramatically sensitized cultured ARHI-expressing ovarian cancer cell lines to glutaminase inhibition. Induction of ARHI resulted in a reduction in mitochondrial respiration, decreased mitochondrial membrane potential, and decreased Tom20 staining suggesting an ARHI-dependent loss of mitochondrial function. ARHI induction in mouse xenograft models resulted in an increase in free amino acids, a transient increase in [18F]-FDG uptake, and significantly altered choline metabolism.ConclusionsARHI expression has previously been shown to trigger autophagy-associated necroptosis in cell culture. In this study, we have demonstrated that ARHI expression results in decreased cellular ATP/ADP, increased oxidative stress, and decreased mitochondrial function. While this bioenergetic shock is consistent with programmed necrosis, our data indicates that the accompanying up-regulation of glycolysis and glutaminolysis is autophagy-dependent and serves to support cell viability rather than facilitate necroptotic cell death. While the mechanistic basis for metabolic up-regulation following ARHI induction is unknown, our preliminary data suggest that decreased mitochondrial function and increased metabolic demand may play a role. These alterations in fundamental metabolic pathways during autophagy-associated necroptosis may provide the basis for new therapeutic strategies for the treatment of dormant ovarian tumors.

【 授权许可】

CC BY   
© The Author(s). 2016