Increased Glucose Availability Sensitizes Pancreatic Cancer to Chemotherapy

Pancreatic Ductal Adenocarcinoma (PDAC) is highly resistant to chemotherapy. Effective alternative therapies have yet to emerge, as chemotherapy remains the best available systemic treatment. However, the discovery of safe and available adjuncts to enhance chemotherapeutic efficacy can still improve survival outcomes. We show that a hyperglycemic state substantially enhances the efficacy of conventional single- and multi-agent chemotherapy regimens against PDAC. Molecular analyses of tumors exposed to high glucose levels reveal that the expression of GCLC (glutamate-cysteine ligase catalytic subunit), a key component of glutathione biosynthesis, is diminished, which in turn augments oxidative anti-tumor damage by chemotherapy. Inhibition of GCLC phenocopies the suppressive effect of forced hyperglycemia in mouse models of PDAC, while rescuing this pathway mitigates anti-tumor effects observed with chemotherapy and high glucose

Voies métaboliques et leurs fonctions dans la leucémogénèse : le rôle de MAPK ERK5

Les cellules cancéreuses utilisent une glycolyse anaérobie pour générer l'ATP au lieu de la phosphorylation oxydative. Cette spécificité métabolique offre certains avantages aux cellules cancéreuses: une prolifération rapide et une évasion immune qui implique la sous-régulation de l'expression du CMH-I à la surface des cellules, phénomène lié au changement métabolique. Dans nos expériences, nous forçons les cellules leucémiques à produire de l'énergie par phosphorylation oxydative en les incubant avec de la glutamine comme source d'énergie en absence de glucose. La respiration ainsi forcée induit une augmentation de la transcription et de l'expression du CMH-I. Ce changement de métabolisme induit aussi une augmentation de l'expression de MAPK ERK5 et son accumulation dans les mitochondries. ERK5 intervient dans les changements de l'expression du CMH-I et du métabolisme. La sur-régulation du CMH-I induite par la respiration est bloquée dans les cellules leucémiques exprimant le shRNA shERK5. ERK5 régule la transcription de l'histone désacétylase de classe III Sirtuin 1 par l'activation de sa cible MEF2, ayant pour conséquence la liaison de MEF2 au promoteur de SIRT1. La régulation transcriptionnelle de SIRT1 induite par ERK5 intervient dans la réponse antioxydante des cellules leucémiques, et la sous-régulation d'ERK5 affecte cette réponse antioxydante. L'augmentation du métabolisme de la glutamine observée dans les cellules leucémiques est initiée par la glutaminase (GLS), enzyme qui est le facteur limitant de la vitesse du métabolisme de la glutamine. miR-23a cible l'ARN messager de GLS et inhibe l'expression de GLS. Le milieu glutamine induit la translocation de p65 dans le noyau, qui mène à une augmentation de l'activité transcriptionnelle de p65. NF-KB p65 inhibe l'expression de miR-23a en amenant HDAC4 sur le promoteur de miR-23a. Cela permet aux cellules leucémiques d'augmenter l'utilisation de la glutamine en tant que source alternative de carbone. Ainsi, la respiration forcée dans les cellules leucémiques contrôle l'expression du CMH-I, la réponse antioxydante et facilite la prolifération tumorale.Cancer cells have anaerobic-like glycolysis to generate ATPs instead of oxidative phosphorylation. This specific metabolism provides advantages to cancer cells: rapid growth and immune evasion, which involves downregulation of MHC-I at the cell surface and it is linked to metabolic change. In our experiments, we force leukemic cells to produce energy by oxidative phosphorylation by incubating them with glutamine as an energy source in the absence of glucose. The forced respiration increases MHC-I transcription and protein level. This change of metabolism also leads to increase MAPK ERK5 expression and accumulation in mitochondria. ERK5 mediates changes in both MHC-I and metabolism. The respiration-induced upregulation of MHC-I is blocked in leukemic cells stably expressing short hairpin ERK5 (shERK5). ERK5 transcriptionally regulates the class III histone deacetylase Sirtuin 1 through activation of its target MEF2 and subsequently MEF2 binding to SIRT1 promoter. The ERK5-induced transcriptional regulation of SIRT1 mediates the antioxidant response in leukemic cells and downregulation of ERK5 impairs the antioxidant response. The increased glutamine metabolism found in leukemic cells is initiated by glutaminase (GLS), a rate limiting enzyme for glutamine metabolism. miR-23a targets GLS mRNA and inhibits GLS expression. The glutamine medium induces p65 translocation to the nucleus that leads to increase p65 transcriptional activity. NF-KB p65 inhibits miR-23a expression by bringing HDAC4 to the miR-23a promoter. This allows leukemic cells to increase the use of glutamine as an alternative source of carbon. Thus, forcing respiration in leukemic cells controls MHC-I expression, antioxidant response and facilitate tumor growth

Voies métaboliques et leurs fonctions dans la leucémogénèse (le rôle de MAPK ERK5)

Les cellules cancéreuses utilisent une glycolyse anaérobie pour générer l'ATP au lieu de la phosphorylation oxydative. Cette spécificité métabolique offre certains avantages aux cellules cancéreuses: une prolifération rapide et une évasion immune qui implique la sous-régulation de l'expression du CMH-I à la surface des cellules, phénomène lié au changement métabolique. Dans nos expériences, nous forçons les cellules leucémiques à produire de l'énergie par phosphorylation oxydative en les incubant avec de la glutamine comme source d'énergie en absence de glucose. La respiration ainsi forcée induit une augmentation de la transcription et de l'expression du CMH-I. Ce changement de métabolisme induit aussi une augmentation de l'expression de MAPK ERK5 et son accumulation dans les mitochondries. ERK5 intervient dans les changements de l'expression du CMH-I et du métabolisme. La sur-régulation du CMH-I induite par la respiration est bloquée dans les cellules leucémiques exprimant le shRNA shERK5. ERK5 régule la transcription de l'histone désacétylase de classe III Sirtuin 1 par l'activation de sa cible MEF2, ayant pour conséquence la liaison de MEF2 au promoteur de SIRT1. La régulation transcriptionnelle de SIRT1 induite par ERK5 intervient dans la réponse antioxydante des cellules leucémiques, et la sous-régulation d'ERK5 affecte cette réponse antioxydante. L'augmentation du métabolisme de la glutamine observée dans les cellules leucémiques est initiée par la glutaminase (GLS), enzyme qui est le facteur limitant de la vitesse du métabolisme de la glutamine. miR-23a cible l'ARN messager de GLS et inhibe l'expression de GLS. Le milieu glutamine induit la translocation de p65 dans le noyau, qui mène à une augmentation de l'activité transcriptionnelle de p65. NF-KB p65 inhibe l'expression de miR-23a en amenant HDAC4 sur le promoteur de miR-23a. Cela permet aux cellules leucémiques d'augmenter l'utilisation de la glutamine en tant que source alternative de carbone. Ainsi, la respiration forcée dans les cellules leucémiques contrôle l'expression du CMH-I, la réponse antioxydante et facilite la prolifération tumorale.Cancer cells have anaerobic-like glycolysis to generate ATPs instead of oxidative phosphorylation. This specific metabolism provides advantages to cancer cells: rapid growth and immune evasion, which involves downregulation of MHC-I at the cell surface and it is linked to metabolic change. In our experiments, we force leukemic cells to produce energy by oxidative phosphorylation by incubating them with glutamine as an energy source in the absence of glucose. The forced respiration increases MHC-I transcription and protein level. This change of metabolism also leads to increase MAPK ERK5 expression and accumulation in mitochondria. ERK5 mediates changes in both MHC-I and metabolism. The respiration-induced upregulation of MHC-I is blocked in leukemic cells stably expressing short hairpin ERK5 (shERK5). ERK5 transcriptionally regulates the class III histone deacetylase Sirtuin 1 through activation of its target MEF2 and subsequently MEF2 binding to SIRT1 promoter. The ERK5-induced transcriptional regulation of SIRT1 mediates the antioxidant response in leukemic cells and downregulation of ERK5 impairs the antioxidant response. The increased glutamine metabolism found in leukemic cells is initiated by glutaminase (GLS), a rate limiting enzyme for glutamine metabolism. miR-23a targets GLS mRNA and inhibits GLS expression. The glutamine medium induces p65 translocation to the nucleus that leads to increase p65 transcriptional activity. NF-KB p65 inhibits miR-23a expression by bringing HDAC4 to the miR-23a promoter. This allows leukemic cells to increase the use of glutamine as an alternative source of carbon. Thus, forcing respiration in leukemic cells controls MHC-I expression, antioxidant response and facilitate tumor growth.MONTPELLIER-BU Médecine UPM (341722108) / SudocSudocFranceF

From tumor cell metabolism to tumor immune escape.

International audienceTumorigenesis implies adaptation of tumor cells to an adverse environment. First, developing tumors must acquire nutrients to ensure their rapid growth. Second, they must escape the attack from the host immune system. Recent studies suggest that these phenomena could be related and that tumor cell metabolism may propel tumor immune escape. Tumor cell metabolism tends to avoid mitochondrial activity and oxidative phosphorylation (OXPHOS), and largely relies on glycolysis to produce energy. This specific metabolism helps tumor cells to avoid the immune attack from the host by blocking or avoiding the immune attack. By changing their metabolism, tumor cells produce or sequester a variety of amino acids, lipids and chemical compounds that directly alter immune function therefore promoting immune evasion. A second group of metabolism-related modification targets the major histocompatibility complex-I (MHC-I) and related molecules. Tumor MHC-I presents tumor-associated antigens (TAAs) to cytotoxic T-cells (CTLs) and hence, sensitizes cancer cells to the cytolytic actions of the anti-tumor adaptive immune response. Blocking tumor mitochondrial activity decreases expression of MHC-I molecules at the tumor cell surface. And peroxynitrite (PNT), produced by tumor-infiltrating myeloid cells, chemically modifies MHC-I avoiding TAA expression in the plasma membrane. These evidences on the role of tumor cell metabolism on tumor immune escape open the possibility of combining drugs designed to control tumor cell metabolism with new procedures of anti-tumor immunotherapy. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy

Chemical Metabolic Inhibitors For The Treatment Of Blood-Borne Cancers.

International audience: Tumor cells, including leukemic cells, remodel their bioenergetic system in favor of aerobic glycolysis. This process is called "the Warburg effect" and offers an attractive pharmacological target to preferentially eliminate malignant cells. In addition, recent results show that metabolic changes can be linked to tumor immune evasion. Mouse models demonstrate the importance of this metabolic remodeling in leukemogenesis. Some leukemias, although treatable, remain incurable and resistance to chemotherapy produces an elevated percentage of relapse in most leukemia cases. Several groups have targeted the specific metabolism of leukemia cells in preclinical and clinical studies to improve the prognosis of these patients, i.e. using L-asparaginase to treat pediatric acute lymphocytic leukemia (ALL). Additional metabolic drugs that are currently being used to treat other diseases or tumors could also be exploited for leukemia, based on preclinical studies. Finally, we discuss the potential use of several metabolic drugs in combination therapies, including immunomodulatory drugs (IMiDs) or immune cell-based therapies, to increase their efficacy and reduce side effects in the treatment of hematological cancers

The NF-κB member p65 controls glutamine metabolism through miR-23a.

International audienceCancer cells have elevated aerobic glycolysis that is termed the Warburg effect. But several tumor cells, including leukemic cells, also increase glutamine metabolism, which is initiated by glutaminase (GLS). The microRNA (miRNA) miR-23 targets GLS mRNA and inhibits expression of GLS protein. Here we show that in human leukemic Jurkat cells the NF-κB p65 subunit binds to miR-23a promoter and inhibits miR-23a expression. Histone deacetylase (HDAC) inhibitors release p65-induced inhibition. Jurkat cells growing in glutamine decrease proliferation due to cell accumulation in G0/G1 phase. Nevertheless, cells get used to this new source of energy by increasing GLS expression, which correlates with an increase in p65 expression and its translocation to the nucleus, leading to a higher basal NF-κB activity. Jurkat cells overexpressing p65 show increase basal GLS expression and proliferate faster than control cells in glutamine medium. Overexpressing miR-23a in leukemic cells impaired glutamine use and induces mitochondrial dysfunction leading to cell death. Therefore, p65 activation decreases miR-23a expression, which facilitates glutamine consumption allowing leukemic cells to use this alternative source of carbon and favoring their adaptation to the metabolic environment

Protein Kinase C-θ (PKC-θ) in Natural Killer Cell Function and Anti-Tumor Immunity.

International audienceThe protein kinase C-θ (PKCθ), which is essential for T cell function and survival, is also required for efficient anti-tumor immune surveillance. Natural killer (NK) cells, which express PKCθ, play a prominent role in this process, mainly by elimination of tumor cells with reduced or absent major histocompatibility complex class-I (MHC-I) expression. This justifies the increased interest of the use of activated NK cells in anti-tumor immunotherapy in the clinic. The in vivo development of MHC-I-deficient tumors is much favored in PKCθ(-/-) mice compared with wild-type mice. Recent data offer some clues on the mechanism that could explain the important role of PKCθ in NK cell-mediated anti-tumor immune surveillance: some studies show that PKCθ is implicated in signal transduction and anti-tumoral activity of NK cells elicited by interleukin (IL)-12 or IL-15, while others show that it is implicated in NK cell functional activation mediated by certain killer-activating receptors. Alternatively, the possibility that PKCθ is involved in NK cell degranulation is discussed, since recent data indicate that it is implicated in microtubule-organizing center polarization to the immune synapse in CD4(+) T cells. The implication of PKC isoforms in degranulation has been more extensively studied in cytotoxic T lymphocyte, and these studies will be also summarized

Human Leukemic Cells performing Oxidative Phosphorylation (OXPHOS) Generate an Antioxidant Response Independently of Reactive Oxygen species (ROS) Production

Tumor cell metabolism is altered during leukemogenesis. Cells performing oxidative phosphorylation (OXPHOS) generate reactive oxygen species (ROS) through mitochondrial activity. To limit the deleterious effects of excess ROS, certain gene promoters contain antioxidant response elements (ARE), e.g. the genes NQO-1 and HO-1. ROS induces conformational changes in KEAP1 and releases NRF2, which activates AREs. We show in vitro and in vivo that OXPHOS induces, both in primary leukemic cells and cell lines, de novo expression of NQO-1 and HO-1 and also the MAPK ERK5 and decreases KEAP1 mRNA. ERK5 activates the transcription factor MEF2, which binds to the promoter of the miR-23a–27a–24-2 cluster. Newly generated miR-23a destabilizes KEAP1 mRNA by binding to its 3′UTR. Lower KEAP1 levels increase the basal expression of the NRF2-dependent genes NQO-1 and HO-1. Hence, leukemic cells performing OXPHOS, independently of de novo ROS production, generate an antioxidant response to protect themselves from ROS