INOS-derived nitric oxide promotes glycolysis by inducing pyruvate kinase M2 nuclear translocation in ovarian cancer.

Linlin Li,Wenhua Huang,Guanghui Xiao,Keyi Li,Wenwen Gao,Lingqun Zhu,Qiuzhen Liu,Mengqiu Huang,Bingtao Hao,Xiqing Li,Qiaohong Yang,Yang Xu,Meng Wang,Kaitai Yao,Zhengjun Liu,Zhuo Zhong,Qianli Wang

doi:10.18632/oncotarget.16523

Abstract

Aerobic glycolysis is essential for tumor growth and survival. Activation of multiple carcinogenic signals contributes to metabolism reprogramming during malignant transformation of cancer. Recently nitric oxide has been noted to promote glycolysis but the mechanism remains elusive. We report here the dual role of nitric oxide in glycolysis: low/physiological nitric oxide (≤ 100 nM) promotes glycolysis for ATP production, oxidative defense and cell proliferation of ovary cancer cells, whereas excess nitric oxide (≥ 500 nM) inhibits it. Nitric oxide has a positive effect on glycolysis by inducing PKM2 nuclear translocation in an EGFR/ERK2 signaling-dependent manner. Moreover, iNOS induced by mild inflammatory stimulation increased glycolysis and cell proliferation by producing low doses of nitric oxide, while hyper inflammation induced iNOS inhibited it by producing excess nitric oxide. Finally, iNOS expression is abnormally increased in ovarian cancer tissues and is correlated with PKM2 expression. Overexpression of iNOS is associated with aggressive phenotype and poor survival outcome in ovarian cancer patients. Our study indicated that iNOS/NO play a dual role of in tumor glycolysis and progression, and established a bridge between iNOS/NO signaling pathway and EGFR/ERK2/PKM2 signaling pathway, suggesting that interfering glycolysis by targeting the iNOS/NO/PKM2 axis may be a valuable new therapeutic approach of treating ovarian cancer.

Highlights

One of fundamental properties of cancer cells is that they underwent metabolic reprogramming from oxidative phosphorylation to aerobic glycolysis during carcinogenesis [1]
We observed that low dose of DETA-NONOate promoted the cell proliferation while the cells died after the treatment with high concentration of Nitric oxide (NO) donor (Figure 1B, right panel)
Using the realtime PCR assay to detect the expressions of the glycolytic genes, the data showed that the mRNA level of the glucose transporter genes (GLUT1, GLUT3), glycolytic enzymes hexokinase genes (HK1, HK2), phosphofructokinase 1 gene (PFK1), 3-phosphoinositide-dependent protein kinase 2 gene (PDK2) and lactate dehydrogenase gene (LDH) were up-regulated in SKOV3 cells treated with NO donor (Figure 3G)

Summary

INTRODUCTION

One of fundamental properties of cancer cells is that they underwent metabolic reprogramming from oxidative phosphorylation to aerobic glycolysis during carcinogenesis [1]. Inducible NOS (iNOS) expression is induced by inflammatory cytokines, hypoxia and oxidative stress in Ca2+-independent way and generates micromolar concentrations of nitric oxide [8,9,10]. Cytosolic PKM2 exists as a tetrameric form with a high activity of pyruvate kinase [18] Under various stimuli such as oxidative stress and growth factor, the tetramer of PKM2 is converted to dimer and translocates into nucleus to function as a protein kinase [19, 20]. It phosphorylates and activates the transcription factors like HIF-1α and MYC for glycolytic gene expression [21]. The higher expression of iNOS in ovarian cancer specimens can predict poor prognosis, supporting the idea of the iNOS as a helpful prognostic marker and a potential therapeutic target for ovary cancer

RESULTS

DISCUSSION

MATERIALS AND METHODS