Search

Hypoxia, which occurs during tumor growth, triggers complex adaptive responses in which peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) plays a critical role in mitochondrial biogenesis and oxidative metabolism. However, how PGC-1α is regulated in response to oxygen availability remains unclear. We demonstrated that lysine demethylase 3A (KDM3A) binds to PGC-1α and demethylates monomethylated lysine (K) 224 of PGC-1α under normoxic conditions. Hypoxic stimulation inhibits KDM3A, which has a high K M of oxygen for its activity, and enhances PGC-1α K224 monomethylation. This modification decreases PGC-1α's activity required for NRF1- and NRF2-dependent transcriptional regulation of TFAM , TFB1M , and TFB2M , resulting in reduced mitochondrial biogenesis. Expression of PGC-1α K224R mutant significantly increases mitochondrial biogenesis, reactive oxygen species (ROS) production, and tumor cell apoptosis under hypoxia and inhibits brain tumor growth in mice. This study revealed that PGC-1α monomethylation, which is dependent on oxygen availability-regulated KDM3A, plays a critical role in the regulation of mitochondrial biogenesis. • Hypoxia suppresses mitochondrial biogenesis of tumor cells • PGC-1α's activity is inhibited by K224 monomethylation under hypoxic conditions • KDM3A senses oxygen availability for its activity and demethylates PGC-1α • PGC-1α monomethylation reduces hypoxia-induced ROS and apoptosis for tumor growth Qian et al. demonstrated that KDM3A functions as an oxygen sensor and demethylates K224-monomethylated PGC-1α under normoxic conditions. Hypoxia inhibits KDM3A activity and increases PGC-1α K224 monomethylation, resulting in the inhibition of PGC-1α and PGC-1α-dependent mitochondrial biogenesis, a decrease of ROS levels and apoptosis, and the promotion of brain tumor development. [ABSTRACT FROM AUTHOR]

The PTEN tumor suppressor is frequently mutated or deleted in cancer and regulates glucose metabolism through the PI3K-AKT pathway. However, whether PTEN directly regulates glycolysis in tumor cells is unclear. We demonstrate here that PTEN directly interacts with phosphoglycerate kinase 1 (PGK1). PGK1 functions not only as a glycolytic enzyme but also as a protein kinase intermolecularly autophosphorylating itself at Y324 for activation. The protein phosphatase activity of PTEN dephosphorylates and inhibits autophosphorylated PGK1, thereby inhibiting glycolysis, ATP production, and brain tumor cell proliferation. In addition, knockin expression of a PGK1 Y324F mutant inhibits brain tumor formation. Analyses of human glioblastoma specimens reveals that PGK1 Y324 phosphorylation levels inversely correlate with PTEN expression status and are positively associated with poor prognosis in glioblastoma patients. This work highlights the instrumental role of PGK1 autophosphorylation in its activation and PTEN protein phosphatase activity in governing glycolysis and tumorigenesis. • PGK1, functioning as a protein kinase, autophosphorylates itself at Y324 • PGK1 autophosphorylation enhances its glycolytic activity via promoting ATP release • PTEN, functioning as a protein phosphatase, dephosphorylates PGK1 pY324 • PGK1 Y324 autophosphorylation promotes brain tumor formation Qian et al. demonstrate that PGK1 functions as a protein kinase and autophosphorylates itself at Y324, leading to subsequent PGK1 activation. This phosphorylation is dephosphorylated by the protein phosphatase activity of PTEN. Loss of PTEN expression in tumors enhances PGK1 activity, thereby promoting glycolysis and brain tumor growth. [ABSTRACT FROM AUTHOR]

Fumarate is an oncometabolite. However, the mechanism underlying fumarate-exerted tumorigenesis remains unclear. Here, utilizing human type2 papillary renal cell carcinoma (PRCC2) as a model, we show that fumarate accumulates in cells deficient in fumarate hydratase (FH) and inhibits PTEN to activate PI3K/AKT signaling. Mechanistically, fumarate directly reacts with PTEN at cysteine 211 (C211) to form S-(2-succino)-cysteine. Succinated C211 occludes tethering of PTEN with the cellular membrane, thereby diminishing its inhibitory effect on the PI3K/AKT pathway. Functionally, re-expressing wild-type FH or PTEN C211S phenocopies an AKT inhibitor in suppressing tumor growth and sensitizing PRCC2 to sunitinib. Analysis of clinical specimens indicates that PTEN C211 succination levels are positively correlated with AKT activation in PRCC2. Collectively, these findings elucidate a non-metabolic, oncogenic role of fumarate in PRCC2 via direct post-translational modification of PTEN and further reveal potential stratification strategies for patients with FH loss by combinatorial AKTi and sunitinib therapy. [Display omitted] • Fumarate directly targets and succinates PTEN at C211 • C211 succination abrogates the interaction of PTEN with the cellular membrane • PTEN C211 succination is positively correlated with PI3K/AKT activation in PRCC2 • Inhibiting PTEN C211 succination or AKT sensitizes PRCC2 to sunitinib treatment Ge et al. report that fumarate, an oncometabolite, succinates PTEN at C211, which abrogates the binding of PTEN with the cellular membrane. C211 succination of PTEN thereby activates PI3K/AKT signaling and promotes tumor growth of PRCC2. Inhibiting PTEN C211 succination or AKT activation enhances sensitivity of PRCC2 to sunitinib treatment. [ABSTRACT FROM AUTHOR]

EGFR T790M mutation causes resistance to the first-generation tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). However, the therapeutic options for sensitizing first TKIs and delaying the emergence of EGFR T790M mutant are limited. In this study, we show that quercetin directly binds with glucose-6-phosphate dehydrogenase (G6PD) and inhibits its enzymatic activity through competitively abrogating NADP + binding in the catalytic domain. This inhibition subsequently reduces intracellular NADPH levels, resulting in insufficient substrate for methionine reductase A (MsrA) to reduce M790 oxidization of EGFR T790M and inducing the degradation of EGFR T790M . Quercetin synergistically enhances the therapeutic effect of gefitinib on EGFR T790M -harboring NSCLCs and delays the acquisition of the EGFR T790M mutation. Notably, high levels of G6PD expression are correlated with poor prognosis and the emerging time of EGFR T790M mutation in patients with NSCLC. These findings highlight the potential implication of quercetin in overcoming EGFR T790M -driven TKI resistance by directly targeting G6PD., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)