NDRG2 Inhibits Pyruvate Carboxylase-Mediated Anaplerosis and Combines with Glutamine Blockade To Inhibit The Growth of Glioma

Abstract

Background Due to the rapid proliferation, cancer cells have increased anabolic biosynthesis, which requires anaplerosis to replenish precursor intermediates. The major anaplerotic sources are pyruvate and glutamine, which require the catalysis of pyruvate carboxylase (PC) and glutaminase (GLS) respectively. In GLS-suppressed cancer cells, the PC-mediated pathway for anaplerosis is crucial to maintain cell growth and proliferation. Here, we investigated the regulatory role and molecular mechanism of the tumor suppressor NDRG2 in PC and PC-mediated anaplerosis. Methods We first evaluated the correlation between PC and NDRG2 in glioma cell lines and human glioma tissue microarrays. The interaction between PC and NDRG2 was tested by tandem affinity purification-mass spectrometry (TAP-MS) and coimmunoprecipitation (Co-IP). We then detected the effect of NDRG2 on PC-mediated anaplerosis by gas chromatography-mass spectrometry (GC-MS). Preclinical evaluation of NDRG2 alone or combined with a glutaminase inhibitor was conducted in glioma cells and xenograft mouse tumors. Results NDRG2 interacted with PC and induced the degradation of PC in glutamine-deficient glioma cells. NDRG2 also inhibited the activity of PC and PC-mediated anaplerosis. As a result, NDRG2 significantly inhibited the malignant growth and proliferation of glioma cells in combination with a glutamine antagonist. In addition, NDRG2 more significantly inhibited the protein level of PC in IDH1(R132H)-mutant glioma cells than in wild-type glioma cells. Conclusions These findings indicate that the molecular mechanism of NDRG2 inhibits PC-mediated anaplerosis and collaborates with glutamine antagonist to inhibit the malignant proliferation of glioma cells, thus providing a theoretical and experimental basis for targeting anaplerosis in glioma therapy.

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“…GBM relies on PC for the glucose-dependent replenishment of the TCA cycle with intermediates, a process known as anaplerosis [ 47 ]. The tumor suppressor NDRG2 inhibits PC expression in IDH-mutant and suppresses glioma growth but this was not observed for IDH-wildtype [ 48 ]. Furthermore, NDRG2 induces the ubiquitination and degradation of PC under glutamine deficiency, and NDRG2 loss leads to increased PC and PC-dependent anaplerosis and glioma tumorigenesis [ 48 ].…”

“…The tumor suppressor NDRG2 inhibits PC expression in IDH-mutant and suppresses glioma growth but this was not observed for IDH-wildtype [ 48 ]. Furthermore, NDRG2 induces the ubiquitination and degradation of PC under glutamine deficiency, and NDRG2 loss leads to increased PC and PC-dependent anaplerosis and glioma tumorigenesis [ 48 ]. In vivo studies have demonstrated that aerobic glycolysis is insufficient to contribute to cellular anaplerosis and support GBM tumor cell growth [ 19 ].…”