Pharmacodynamic Effects of AG-946, a Highly Potent Next-Generation Activator of Pyruvate Kinase, in Ex Vivo Treatment of Red Blood Cells from Sickle Cell Disease Patients

Background: Sickle cell disease (SCD) is a monogenetic red blood disorder that is characterized by hemolytic anemia and vaso-occlusive crises. Among the many factors that contribute to disease pathophysiology is stiffening and sickling of red blood cells (RBC), which is the direct result of the formation of abnormal hemoglobin S. Sickling is one of the core factors that cause vaso-occlusion and sickling is modulated by glycolytic intermediates such as 2,3-diphosphoglycerate (2,3-DPG) and ATP. Previously we showed that red blood cell pyruvate kinase (PKR), the key regulatory enzyme of glycolysis, is impaired in SCD and that ex vivo treatment with mitapivat, an allosteric activator of PKR, increased enzymatic activity and thermostability, reduced 2,3-DPG levels, decreased p50, and subsequently reduced sickling (Rab et al, Blood 2021). Currently, mitapivat is in phase 1 and phase 2 trials for SCD (#NCT04000165 and EudraCT#2019-003438). Aims: Recently, AG-946, a next-generation activator of PKR has been developed. Here we investigate the pharmacodynamic effects of AG-946 in ex vivo treatment of RBC from SCD patients in comparison with mitapivat. Methods: Buffy coat depleted whole blood obtained from five patients with SCD was incubated for 20-24 hrs in absence or presence of mitapivat (100 mM) or AG-946 (1 mM, 5 mM, 50 mM). After ex vivo treatment, enzymatic activities of PKR and PK-thermostability was measured. Glycolytic intermediates ATP and 2,3-DPG were measured using LC-MS/MS. Hemoglobin oxygen affinity (p50) was measured with the Hemox Analyzer. RBC sickling was analyzed with the oxygenscan, a newly developed method that characterizes individual sickling behavior by oxygen gradient ektacytometry. Individual tendency to sickle is reflected by Point-of-Sickling (PoS) that indicates the specific pO 2 at which RBCs start to sickle during deoxygenation under shear stress. Results: PKR activity was increased compared to vehicle (DMSO) to a similar extent in presence of both mitapivat and AG-946 (Figure 1A). In addition, PKR thermostability was significantly increased compared to vehicle (mean 22%, SD 6%) in samples treated with mitapivat 100 mM (mean 78%, SD 11%), as well as AG-946 5 mM (mean 66%, SD 23%), and AG-946 50 mM (mean 95%, SD 17%, Figure 1B). The glycolytic intermediate 2,3-DPG decreased after incubation with both mitapivat and AG-946 (Figure 1C), which was further illustrated by the improved ATP/2,3-DPG ratio (Figure 1D). In line with these latter results p50 decreased significantly after incubation with mitapivat 100 mM (mean 95%, SD 2%), as well as AG-946 1 mM (mean 96%, SD 2%), AG-946 5 mM (mean 94%, SD 2%), and AG-946 50 mM (mean 95%, SD 3%, Figure 1E). The improved metabolic status and p50 was accompanied by a decreased PoS compared to vehicle in RBCs treated with mitapivat or AG-946, indicating reduced RBC sickling tendency in vitro (Figure 1F). Conclusion: Ex vivo treatment of SCD RBCs with the next-generation PKR activator AG-946 activates and stabilizes PK, decreases 2,3-DPG levels, improves the ATP/2,3-DPG ratio, improves p50 and lowers the PoS. These beneficial effects are similar to ex vivo treatment with mitapivat but, importantly, are obtained at much lower concentrations. Therefore, AG-946 may be a potent activator of PKR in SCD. Taken together, these results are the first in an ex vivo model to demonstrate that the next-generation PK activator AG-946 has a similar favorable pharmacodynamic profile to mitapivat with enhanced PK-stabilizing properties and, hence, represents a potential novel therapeutic option in addition to mitapivat for the treatment of SCD and other hemolytic anemias. Figure 1 Figure 1. Disclosures Rab: Axcella Health: Research Funding; Agios Pharmaceuticals: Research Funding. Van Dijk: Axcella Health: Research Funding; Agios Pharmaceuticals: Research Funding. Kosinski: Agios Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Kung: Agios Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Van Beers: Pfizer: Research Funding; RR Mechatronics: Research Funding; Novartis: Research Funding; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding. Dang: Agios Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Wijk: Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Axcella health: Research Funding; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Mutations in the Hemoglobin Binding Domain of Band 3 Perturb Cellular Metabolism and Alter the Sickling of SS Erythrocytes

Under oxygenated conditions, 4 glycolytic enzymes that perform the terminal steps of glycolysis (phospho-fructoKinase [PFK], lactate dehydrogenase [LDH], aldolase [ALD] and glygeraldehyde 3 phosphate dehydrogenase [GAPDH]) bind to the cytoplasmic domain of band 3. Under deoxy conditions deoxy hemoglobin (Hb) is bound to band 3 and PFK, LDH, ALD and GAPDH are displaced (Campanella et al. PNAS 102, 2005; Blood 112, 2008). We generated transgenic mice in which the sequence encoding the first 35 amino acids of the wild type human band 3 cytoplasmic domain replaced the endogenous mouse band 3 sequences in the Slc4a1 gene, a mutant line in which human amino acids 12-21 were deleted removing the deoxy Hb binding site (-Hb) and a third line in which amino acids 1-11 were deleted creating a high affinity binding site for deoxyHb (++Hb). Erythrocytes from the mutant lines were insensitive to Oxygen concentration resulting in changes in oxygen dependent deformability and other physical properties compared to the wild type line (Chu et al. Blood 128, 2016, Zheng et al. JBC 294, 2019, Zhou et al. Sci. Adv. 5, 2019). We crossed our humanized band 3 mouse strains to the Townes Sickle Cell Disease (SCD) mouse model, maintaining both the human βA and βS alleles to generate human AA, AS and SS mice homozygous for each of the human band 3 cytoplasmic domain sequences. Using an assay in which SS red cells in phosphate buffer are deoxygenated to 6% oxygen over time (Dunkelberger et al., J. Phys. Chem. B 122, 2018), we observed that -Hb band 3/SS mice showed an accelerated rate of sickle cell formation and a higher percent of sickled cells than wild type band 3/SS mice (p<0.01). Conversely, ++Hb band 3/SS mice showed an inhibition of both the rate of sickling and the precent of sickled cells compared to wild type band 3/SS mice (p<0.05). We hypothesized that the inability of the glycolytic enzymes to reversibly bind to band 3 in the mutant mice were responsible for the differences in sickling. To test this hypothesis, we analyzed a panel of 28 cellular metabolites in 12 mice (6 female, 6 male) of each genotype: wild type band 3/AA, -AS and -SS, -Hb band 3/AA, -AS, -SS and ++Hb/AA, -AS, -SS. The metabolites were quantified by LC-MS/MS using an API 4500 triple quadrupole mass spectrometer (AB Sciex), with chromatographic resolution enabled on a polymeric amino column (apHera by Supelco) under alkaline mobile phase conditions (pH ~9.3). Stable isotope dilution and 8pt calibration curves allowed the absolute quantification of each metabolite. Consistent with the constitutive binding of the terminal glycolytic enzymes to band 3 in -Hb erythrocytes, glycolysis was inhibited after the phosphoenol pyruvate step, as evidenced by significant accumulation of the intermediates at top of the glycolysis pathway, including fructose 1,6 biphosphate (FBP; p<0.01), dihydroxyacetone phosphate/ glyceraldehyde-3-phosphate (G3P; p<0.01), and 3-phosphoglycerate/2-phosphoglycerate (PG; p<0.01). In the ++Hb mutant where the terminal glycolytic enzymes are constitutively displaced from band 3, significantly lower levels of FBP, G3P and PG were observed (p<0.01). The levels of these metabolites in wild type band 3/SS erythrocytes were intermediate between the two mutant strains. We hypothesized that the accumulation of FBP, G3P and PG contributed to the increased rate of sickling in the -Hb band 3/SS mice. To test this, we incubated wild type band 3/SS cells with either FBP or PG. Both intermediates increased the rate of sickle cell formation and percentage of sickled cells in a dose dependent fashion with no alteration in any RBC indices including MCV and osmotic fragility. We next hypothesized that reduction of the levels of glycolytic intermediates would have an antisickling effect. To test this, we incubated wild type band 3/SS cells with 2,3 diphosphoglycerol (DPG), which is a potent inhibitor of glycolysis. We found that DPG treatment led to a dose dependent decrease in the rate of sickle cell formation and percentage of sickled cells, again with no alteration in any RBC indices including MCV and osmotic fragility. We conclude that the accumulation of glycolytic intermediates leads to increased sickle cell formation. We propose that reduction in the levels of glycolytic intermediates either by accelerating the terminal stages of glycolysis or by redirection to the pentose phosphate pathway may offer a means to treat SCD. Disclosures No relevant conflicts of interest to declare.

Salmonella Typhimurium reprograms macrophage metabolism via T3SS effector SopE2 to promote intracellular replication and virulence

Salmonella Typhimurium establishes systemic infection by replicating in host macrophages. Here we show that macrophages infected with S. Typhimurium exhibit upregulated glycolysis and decreased serine synthesis, leading to accumulation of glycolytic intermediates. The effects on serine synthesis are mediated by bacterial protein SopE2, a type III secretion system (T3SS) effector encoded in pathogenicity island SPI-1. The changes in host metabolism promote intracellular replication of S. Typhimurium via two mechanisms: decreased glucose levels lead to upregulated bacterial uptake of 2- and 3-phosphoglycerate and phosphoenolpyruvate (carbon sources), while increased pyruvate and lactate levels induce upregulation of another pathogenicity island, SPI-2, known to encode virulence factors. Pharmacological or genetic inhibition of host glycolysis, activation of host serine synthesis, or deletion of either the bacterial transport or signal sensor systems for those host glycolytic intermediates impairs S. Typhimurium replication or virulence.

Increasing glycolysis by deletion of kcs1 and arg82 improved S-adenosyl-l-methionine production in Saccharomyces cerevisiae

Reprogramming glycolysis for directing glycolytic metabolites to a specific metabolic pathway is expected to be useful for increasing microbial production of certain metabolites, such as amino acids, lipids or considerable secondary metabolites. In this report, a strategy of increasing glycolysis by altering the metabolism of inositol pyrophosphates (IPs) for improving the production of S-adenosyl-l-methionine (SAM) for diverse pharmaceutical applications in yeast is presented. The genes associated with the metabolism of IPs, arg82, ipk1 and kcs1, were deleted, respectively, in the yeast strain Saccharomyces cerevisiae CGMCC 2842. It was observed that the deletions of kcs1 and arg82 increased SAM by 83.3 % and 31.8 %, respectively, compared to that of the control. In addition to the improved transcription levels of various glycolytic genes and activities of the relative enzymes, the levels of glycolytic intermediates and ATP were also enhanced. To further confirm the feasibility, the kcs1 was deleted in the high SAM-producing strain Ymls1ΔGAPmK which was deleted malate synthase gene mls1 and co-expressed the Acetyl-CoA synthase gene acs2 and the SAM synthase gene metK1 from Leishmania infantum, to obtain the recombinant strain Ymls1Δkcs1ΔGAPmK. The level of SAM in Ymls1Δkcs1ΔGAPmK reached 2.89 g L−1 in a 250-mL flask and 8.86 g L−1 in a 10-L fermentation tank, increasing 30.2 % and 46.2 %, respectively, compared to those levels in Ymls1ΔGAPmK. The strategy of increasing glycolysis by deletion of kcs1 and arg82 improved SAM production in yeast.

RIP140 inhibits glycolysis-dependent proliferation of cancer cells by regulating transcriptional crosstalk between hypoxia induced factor and p53

Cancer cells with uncontrolled proliferation preferentially depend on glycolysis to grow, even in the presence of oxygen. Cancer cell proliferation is sustained by the production of glycolytic intermediates, which are diverted into the pentose phosphate pathway. The transcriptional co-regulator RIP140 represses the activity of transcription factors that drive cell proliferation and metabolism, especially glycolysis. However, it is still unknown whether RIP140 is involved in cancer-associated glycolysis deregulation, and whether this involvement could impact tumor cell proliferation. Here we use cell proliferation and metabolic assays to demonstrate that RIP140-deficiency causes a glycolysis-dependent increase in breast tumor growth. RIP140 inhibits the expression of the glucose transporter GLUT3 and of the Glucose-6-Phosphate Dehydrogenase G6PD, the first enzyme of the pentose phosphate pathway. RIP140 thus impacts both this pathway and glycolysis to block cell proliferation. We further demonstrate that RIP140 and p53 jointly inhibit the transcription of the GLUT3 promoter, induced by the hypoxia inducible factor HIF-2α. Overall, our data establish RIP140 as a critical modulator of the p53/HIF cross-talk that controls cancer glycolysis.

Drosophila TRIM32 cooperates with glycolytic enzymes to promote cell growth

Cell growth and/or proliferation may require the reprogramming of metabolic pathways, whereby a switch from oxidative to glycolytic metabolism diverts glycolytic intermediates towards anabolic pathways. Herein, we identify a novel role for TRIM32 in the maintenance of glycolytic flux mediated by biochemical interactions with the glycolytic enzymes Aldolase and Phosphoglycerate mutase. Loss of Drosophila TRIM32, encoded by thin (tn), shows reduced levels of glycolytic intermediates and amino acids. This altered metabolic profile correlates with a reduction in the size of glycolytic larval muscle and brain tissue. Consistent with a role for metabolic intermediates in glycolysis-driven biomass production, dietary amino acid supplementation in tn mutants improves muscle mass. Remarkably, TRIM32 is also required for ectopic growth - loss of TRIM32 in a wing disc-associated tumor model reduces glycolytic metabolism and restricts growth. Overall, our results reveal a novel role for TRIM32 for controlling glycolysis in the context of both normal development and tumor growth.

Membrane-Bound O-Acyltransferase 7 (MBOAT7) is a Key Regulator of Glycolysis in Clear Cell Renal Carcinoma

ObjectiveThe most common and deadliest urological cancer is clear cell Renal Cell Carcinoma (ccRCC). ccRCC is characterized by striking reorganization of both carbohydrate and lipid metabolism. It was recently demonstrated that lipid remodeling enzyme Membrane-Bound O-Acyltransferase 7 (MBOAT7) that generates phosphatidylinositol (PI) is important for the ccRCC progression. However, whether MBOAT7-driven PI remodeling is associated with other metabolic alterations commonly found in ccRCC is poorly understood.MethodsMBOAT7 deficient ccRCC cell lines were generated by genome editing, and were characterized by a general reduction in glycolytic capactiy. Using targeted metabolomics approach in Caki-1 cells, we measured the glycolytic intermediates and the relative expression of key glycolytic enzymes. We also measured basal respiration and maximal respiration with MBOAT7 deficiency in the presence of glucose. Lastly, in vivo xenograft studies were performed with parental and MBOAT7 deficient cells.ResultsMBOAT7 deficiency was associated with a reduction in glycolytic gene expression and protein abundance. In parallel, we found that glycolytic intermediates similarly decreased which may contribute to a reduction in glycolysis. MBOAT7 deficiency reduces basal respiration and maximal respiration. Similarly, we see maximum glycolytic capacity also reduced with MBOAT7 loss of function. Finally, the in vivo xenograft demonstrated MBOAT7 knockout significantly increased overall survival and reduced glycolytic HK2 protein abundance in vivo.ConclusionsOur work highlights MBOAT7 as a key regulator of glycolysis in ccRCC. Our data provides additional evidence that suggests MBOAT7 as a novel target to regulate tumor growth in vivo.