Nutrient Condition in the Microenvironment Determines Essential Metabolisms of CD8(+) T Cells for Enhanced IFN gamma Production by Metformin

Metformin (Met), a first-line drug for type 2 diabetes, lowers blood glucose levels by suppressing gluconeogenesis in the liver, presumably through the liver kinase B1-dependent activation of AMP-activated protein kinase (AMPK) after inhibiting respiratory chain complex I. Met is also implicated as a drug to be repurposed for cancers; its mechanism is believed identical to that of gluconeogenesis inhibition. However, AMPK activation requires high Met concentrations at more than 1 mM, which are unachievable in vivo. The immune-mediated antitumor response might be the case in a low dose Met. Thus, we proposed activating or expanding tumor-infiltrating CD8(+) T cells (CD8TILs) in a mouse model by orally administering Met in free drinking water. Here we showed that Met, at around 10 mu M and a physiologically relevant concentration, enhanced production of IFN gamma,TNF alpha and expression of CD25 of CD8(+) T cells upon TCR stimulation. Under a glucose-rich condition, glycolysis was exclusively involved in enhancing IFN gamma production. Under a low-glucose condition, fatty acid oxidation or autophagy-dependent glutaminolysis, or both, was also involved. Moreover, phosphoenolpyruvate carboxykinase 1 (PCK1), converting oxaloacetate to phosphoenolpyruvate, became essential. Importantly, the enhanced IFN gamma production was blocked by a mitochondrial ROS scavenger and not by an inhibitor of AMPK. In addition, IFN gamma production by CD8TILs relied on pyruvate translocation to the mitochondria and PCK1. Our results revealed a direct effect of Met on IFN gamma production of CD8(+) T cells that was dependent on differential metabolic pathways and determined by nutrient conditions in the microenvironment

HSP60 possesses a GTPase activity and mediates protein folding with HSP10

The mammalian molecular chaperone, HSP60, plays an essential role in protein homeostasis through mediating protein folding and assembly. The structure and ATP-dependent function of HSP60 has been well established in recent studies. After ATP, GTP is the major cellular nucleotide. In this paper, we have investigated the role of GTP in the activity of HSP60. It was found that HSP60 has different properties with respect to allostery, complex formation and protein folding activity depending on the nucleoside triphosphate present. The presence of GTP slightly affected the ATPase activity of HSP60 during protein folding. These results provide clues as to the functional mechanism of the HSP60-HSP10 complex

アリル炭化水素受容体とHSP90シャペロン複合体機能の解析に関する研究

博士（理学）秋田大

HSP60 possesses a GTPase activity and mediates protein folding with HSP10

Abstract The mammalian molecular chaperone, HSP60, plays an essential role in protein homeostasis through mediating protein folding and assembly. The structure and ATP-dependent function of HSP60 has been well established in recent studies. After ATP, GTP is the major cellular nucleotide. In this paper, we have investigated the role of GTP in the activity of HSP60. It was found that HSP60 has different properties with respect to allostery, complex formation and protein folding activity depending on the nucleoside triphosphate present. The presence of GTP slightly affected the ATPase activity of HSP60 during protein folding. These results provide clues as to the functional mechanism of the HSP60-HSP10 complex

Blocking EP4 downregulates tumor metabolism and synergizes with anti-PD-1 therapy to activate natural killer cells in a lung adenocarcinoma model

Prostaglandin E2 (PGE2), a product of the cyclooxygenase (COX) pathway, is produced by tumors and surrounding stromal cells. It stimulates tumor progression, promotes angiogenesis, and suppresses the antitumor response. Pharmacological inhibition of PGE2 synthesis has been shown to suppress tumor initiation and growth in vivo. In the current study, we demonstrated that the growth of the Ptgs2-deficient the 3LL lung adenocarcinoma cell line was downregulated in vivo through natural killer (NK) cell activation and a reduction in the population of polymorphonuclear leukocyte-myeloid-derived suppressor cells (PMN-MDSCs) and tumor associated macrophages (TAMs). Based on these results, the therapeutic effect of ONO-AE3–208 (EP4i), an inhibitor of EP4 (a PGE2 receptor), combined with anti-PD-1Ab was evaluated. EP4i, but not anti-PD-1 Ab, decreased tumor metabolism including glycolysis, fatty acid oxidation, and oxidative phosphorylation. EP4i induced IFNγ production from only NK cells (not from T cells) and a shift from M2- to M1-like macrophages in TAMs. These effects were further enhanced by anti-PD-1 Ab treatment. Although CD8T cell infiltration was increased, IFNγ production was not significantly altered, even with combination therapy. Tumor hypoxia was ameliorated by either EP4i or anti-PD-1 Ab treatment, which was further affected by the combination. Normalization of tumor vessels was significant only for the combination therapy. The results indicate a novel effect of EP4i for the metabolic reprogramming of tumors, revealed unique features of EP4i that can synergize with anti-PD-1Ab to promote IFNγ production of NK cells, polarize TAMs into the M1-phenotype, and reduce hypoxia through normalization of the tumor vasculature

GNG11 (G-protein γ subunit 11) suppresses cell growth with induction of reactive oxygen species and abnormal nuclear morphology in human SUSM-1 cells

Enforced expression of GNG11, G-protein Îł subunit 11, induces cellular senescence in normal human diploid fibroblasts. We here examined the effect of the expression of GNG11 on the growth of immortalized human cell lines, and found that it suppressed the growth of SUSM-1 cells, but not of HeLa cells. We then compared these two cell lines to understand the molecular basis for the action of GNG11. We found that expression of GNG11 induced the generation of reactive oxygen species (ROS) and abnormal nuclear morphology in SUSM-1 cells but not in HeLa cells. Increased ROS generation by GNG11 would likely be caused by the down-regulation of the antioxidant enzymes in SUSM-1 cells. We also found that SUSM-1 cells, even under normal culture conditions, showed higher levels of ROS and higher incidence of abnormal nuclear morphology than HeLa cells, and that abnormal nuclear morphology was relevant to the increased ROS generation in SUSM-1 cells. Thus, SUSM-1 and HeLa cells showed differences in the regulation of ROS and nuclear morphology, which might account for their different responses to the expression of GNG11. Then, SUSM-1 cells may provide a unique system to study the regulatory relationship between ROS generation, nuclear morphology, and G-protein signaling.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author