Glutaminase 2 negatively regulates the PI3K/AKT signaling and shows tumor suppression activity in human hepatocellular carcinoma
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Juan Liu 1,4, Cen Zhang 1,4, Meihua Lin 1, Wei Zhu1,2, Yingjian Liang 1, Xuehui Hong 1,2,Yuhan Zhao1,2, Ken H. Young 3, Wenwei Hu 1,2 , Zhaohui Feng 1
1 Department of Radiation Oncology,
2 Department of Pediatrics, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA
3 Department of Hematopathology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
4 These two authors contributed equally to this work
Wenwei Hu, email:
Zhaohui Feng, email:
Keywords:p53; GLS2; tumor suppression; PI3K/AKT; Hepatocellular carcinoma
Received: February 15, 2014 Accepted: March 24, 2014 Published: March 26, 2014
The tumor suppressor p53 and its signaling pathway play a critical role in tumor prevention. As a direct p53 target gene, the role of glutaminase 2 (GLS2) in tumorigenesis is unclear. In this study, we found that GLS2 expression is significantly decreased in majority of human hepatocellular carcinoma (HCC). Restoration of GLS2 expression in HCC cells inhibits the anchorage-independent growth of cells and reduces the growth of HCC xenograft tumors. Interestingly, we found that GLS2 negatively regulates the PI3K/AKT signaling, which is frequently activated in HCC. Blocking the PI3K/AKT signaling in HCC cells largely abolishes the inhibitory effect of GLS2 on the anchorage-independent cell growth and xenograft tumor growth. The GLS2 promoter is hypermethylated in majority of HCC samples. CpG methylation of GLS2 promoter inhibits GLS2 transcription, whereas reducing the methylation of GLS2 promoter induces GLS2 expression. Taken together, our results demonstrate that GLS2 plays an important role in tumor suppression in HCC, and the negative regulation of PI3K/AKT signaling contributes greatly to this function of GLS2. Furthermore, hypermethylation of GLS2 promoter is an important mechanism contributing to the decreased GLS2 expression in HCC.
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