Many cancer cells rely on aerobic glycolysis for energy production and targeting of this pathway is a potential strategy to inhibit cancer cell growth. In this study, inhibition of five glycolysis pathway molecules (GLUT1, HKII, PFKFB3, PDHK1 and LDH) using 9 inhibitors (Phloretin, Quercetin, STF31, WZB117, 3PO, 3-bromopyruvate, Dichloroacetate, Oxamic acid, NHI-1) was investigated in panels of breast and ovarian cancer cell line models. All compounds tested blocked glycolysis as indicated by increased extracellular glucose and decreased lactate production and also increased apoptosis. Sensitivity to several inhibitors correlated with the proliferation rate of the cell lines. Seven compounds had IC50 values that were associated with each other consistent with a shared mechanism of action. A synergistic interaction was revealed between STF31 and Oxamic acid when combined with the antidiabetic drug metformin. Sensitivity to glycolysis inhibition was also examined under a range of O2 levels (21% O2, 7% O2, 2% O2 and 0.5% O2) and greater resistance to the inhibitors was found at low oxygen conditions (7% O2, 2% O2 and 0.5% O2) relative to 21% O2 conditions. These results indicate growth of breast and ovarian cancer cell lines is dependent on all the targets examined in the glycolytic pathway with increased sensitivity to the inhibitors under normoxic conditions.

BackgroundNovel therapeutic approaches are required to treat ovarian cancer and dependency on glycolysis may provide new targets for treatment. This study sought to investigate the variation of expression of molecular components (GLUT1, HKII, PKM2, LDHA) of the glycolytic pathway in ovarian cancers and the effectiveness of targeting this pathway in ovarian cancer cell lines with inhibitors.MethodsExpression of GLUT1, HKII, PKM2, LDHA were analysed by quantitative immunofluorescence in a tissue microarray (TMA) analysis of 380 ovarian cancers and associations with clinicopathological features were sought. The effect of glycolysis pathway inhibitors on the growth of a panel of ovarian cancer cell lines was assessed by use of the SRB proliferation assay. Combination studies were undertaken combining these inhibitors with cytotoxic agents.ResultsMean expression levels of GLUT1 and HKII were higher in high grade serous ovarian cancer (HGSOC), the most frequently occurring subtype, than in non-HGSOC. GLUT1 expression was also significantly higher in advanced stage (III/IV) ovarian cancer than early stage (I/II) disease. Growth dependency of ovarian cancer cells on glucose was demonstrated in a panel of ovarian cancer cell lines. Inhibitors of the glycolytic pathway (STF31, IOM-1190, 3PO and oxamic acid) attenuated cell proliferation in platinum-sensitive and platinum-resistant HGSOC cell line models in a concentration dependent manner. In combination with either cisplatin or paclitaxel, 3PO (a novel PFKFB3 inhibitor) enhanced the cytotoxic effect in both platinum sensitive and platinum resistant ovarian cancer cells. Furthermore, synergy was identified between STF31 (a novel GLUT1 inhibitor) or oxamic acid (an LDH inhibitor) when combined with metformin, an inhibitor of oxidative phosphorylation, resulting in marked inhibition of ovarian cancer cell growth.ConclusionsThe findings of this study provide further support for targeting the glycolytic pathway in ovarian cancer and several useful combinations were identified.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4521-4) contains supplementary material, which is available to authorized users.

Hepatocellular carcinoma (HCC) is an endemic disease globally, with a 5-year survival rate of 15%. Current treatment of late-stage HCC involves the use of chemotherapy and sorafenib, a multi-kinase inhibitor. Metabolic studies have indicated HCC has a high glycolysis rate, and is surrounded by a hypoglycemic microenvironment. Given the need for therapeutic options for HCC and its glycolytic nature, this study explored the activity of novel GLUT1 inhibitors in varied glucose concentrations. To assess target inhibition, [3H] deoxy-D-glucose (2DG) uptake assays were performed in HEK293 cells stably over-expressing GLUT1-4 individually. Six HCC cell lines were cultured in media with standard high glucose (HG:25mM) and low glucose/lactic acidosis (LGLA: 5mM glucose/20mM lactic acid) to mimic the hypoglycemic microenvironment. IC50s were assessed using the SRB assay, and other phenotypes using standard methods. Four novel GLUT1 inhibitors (IOM1-4) from the same chemical series were identified from diversity screening. The compounds exhibited differential potencies to GLUT proteins at the sub-μM level. The inhibitors reduced the uptake of 2DG, the extrusion of lactate, and increased apoptosis. In HCC cells, IC50s were lowest with IOM1 and 2 and highest with IOM4 (Table 1). HEP3B cells displayed exceptional sensitivity to the inhibitors. The ranking of potency according to the IC50s correlated with the 2DG uptake studies. There was no correlation between GLUT protein levels and IC50s. Significant differences in sensitivity to inhibitors were observed in cells cultured in HG and LGLA conditions. Cells cultured in LGLA had consistently lower glucose uptake compared those in HG conditions. In LGLA conditions, cells with low levels of reactive oxygen species (ROS) were more sensitive to GLUT1 inhibitors compared to cells with high ROS levels. In conclusion, GLUT1 inhibition can be influenced by microenvironment glucose levels and could be a strategy for HCC treatment. IC50 values (uM) for respective inhibitors in respective HCC cell linesCELL LINESInhibitorCultureC3AHEP3BHUH7PLCSKHEP1SNU449IOM1HG>5.00.8±0.040.3±0.06>5.01.4±0.451.7±0.38IOM1LGLA>5.00.2±0.134.0±1.20>5.00.1±0.021.6±0.28IOM2HG4.7±0.44<0.011.0±0.562.4±0.690.3±0.050.9±0.42IOM2LGLA>5.00.1±0.080.2±0.093.2±1.290.1±0.021.3±0.42IOM3HG>5.00.2±0.040.9±0.222.3±0.251.1±0.641.6±0.40IOM3LGLA>5.0<0.012.7±1.29>5.00.4±0.092.3±1.13IOM4HG>5.02.8±0.354.3±1.494.6±1.404.7±0.85>5.0IOM4LGLA>5.01.4±0.493.8±1.10>5.03.1±0.56>5.0 Citation Format: Bhaskar Bhattacharya, Sanamerjit S. Mann, Min Ji Han, Sarah HH Low, Gim Hwa Tan, Barry E. McGuinness, Sarah C. Trewick, Phillip M. Cowley, Alan Wise, Richie Soong. Identification and activity of novel GLUT1 inhibitors in hepatocellular carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1283.

The enzymes tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO1) catalyse oxidation of the essential amino acid tryptophan (Trp) leading to the formation of immunosuppressive kynurenine (Kyn) pathway metabolites that dampen the immune response in the tumor microenvironment. Both IDO1 and TDO have been shown to be up-regulated in a variety of cancers and blockade of their activity has been shown to stimulate the anti-tumour immune response in pre-clinical animal models. We have discovered and optimized multiple novel chemical series of both highly selective and dual-acting inhibitors of IDO1 and TDO. We describe the characterization of molecules that we are progressing into the clinic. We have characterized the IDO1 and TDO-selective inhibitors and dual-acting inhibitors which demonstrate nM potencies. In IFNγ-stimulated A172 glioblastoma cells expressing both enzymes, the dual-acting molecules fully inhibit Kyn production, whilst selective inhibitors yield only a partial response, demonstrating the utility of dual enzyme blockade in cancer cells. The compounds also relieve inhibition of T-cell proliferation in cancer cell conditioned media/T-cell co-culture assays and demonstrate highly favourable physico-chemical and pharmacokinetic properties. These properties translate to superior PK/PD effects following oral dosing in rodents with profound and sustained modulation of plasma Kyn levels, combined with an exceptional safety profile. In a mouse model of LPS-induced IDO1 activation, our IDO1 inhibitors fully ablate elevation of Kyn in both plasma and lung in a dose-dependent manner. Following oral administration, the IOmet IDO1 inhibitors provide excellent single-agent tumor growth control in PAN02 pancreatic adenocarcinoma syngeneic models. In addition, combining IOmet IDO1 inhibitors with standard-of-care chemotherapy (gemcitabine/abraxane) in the PAN02 model completely inhibits tumor growth. In summary, we describe the characterization of novel potent, selective and dual-acting IDO1 and TDO inhibitors. These candidate molecules demonstrate excellent rodent in vivo PK/PD, safety and anti-tumor profiles, supporting their progression into the clinic. Citation Format: Alan Wise, Barry E. McGuinness, Sarah C. Trewick, Thomas J. Brown, Phillip M. Cowley. Pre-clinical development of next generation inhibitors of the enzymes indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase as cancer immunotherapies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5115.

Introduction: TDO (tryptophan 2,3-dioxygenase) and IDO (indoleamine 2,3-dioxygenase) are structurally distinct enzymes that catalyse the oxidation of tryptophan (Trp) leading to local Trp depletion and formation of immunesuppressive kynurenine pathway (KP) metabolites and dampening of the immune response in the tumour environment. IDO is known to be up-regulated in numerous cancers. Recently, TDO was shown to be up-regulated in various tumour types. Hence, selective IDO inhibitors may have a limited effect in cancers harbouring both TDO and IDO. To test this hypothesis we utilised recently identified proprietary dual-active and highly selective TDO/IDO inhibitors to modulate kynurenine (Kyn) levels in glioma cancer cells expressing either TDO alone or expressing both TDO and IDO. In addition, we measured Kyn modulation in human peripheral blood mononuclear cells (PBMCs) following exposure to dual and selective inhibitors. Methods: Assays were established to measure the effects of dual-active and highly selective TDO/IDO inhibitors on Kyn production in 1) human A172 glioma cells naturally expressing TDO alone or expressing both TDO and IDO following IDO induction using Interferon γ (IFNΓ) and in 2) freshly isolated human PBMCs treated with IFNΓ. Results: Dual-active and selective TDO/IDO inhibitors demonstrated distinct Kyn modulating activities in A172 glioma cells expressing either TDO alone or both TDO and IDO. Dual-active molecules fully ablated Kyn levels in both TDO-expressing and TDO/IDO-expressing cells. Crucially, selective inhibitors were unable to fully block Kyn in A172 cells co-expressing both enzymes. As expected TDO-selective inhibitors were highly active in A172 cells expressing TDO alone. IDO-selective inhibitors were largely inactive in A172 cells naturally expressing TDO alone. However, they gained significant activity upon induction of IDO in these cells following IFNΓ exposure. Interestingly, TDO-selective inhibitors were unable to modulate Kyn levels in PBMCs whereas IDO-selective and dual-active molecules were able to potently block Kyn production. Discussion: These data demonstrate that dual-active TDO/IDO inhibitors are most effective at reducing Kyn levels in cancer cells co-expressing TDO and IDO. In addition, the data suggest that IFNΓ-treated PBMCs primarily express IDO with no measurable Kyn production from TDO. This study demonstrates the utility of applying highly selective and dual active inhibitors of these Trp-catabolizing enzymes as probes for defining the Kyn-producing component from PBMCs. In summary, blocking both TDO and IDO activity with dual-active inhibitors maybe complementary rather than redundant in cancers harbouring both of these enzymes; and IDO appears to be the primary enzyme driving Trp metabolism in PBMCs. Citation Format: Alan Wise, Barry E. McGuinness, Sarah C. Trewick, Phillip M. Cowley, Nicola Bevan, Clare Szybut, Thomas J. Brown. In vitro kynurenine modulation by novel dual-acting and selective tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO) inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4292. doi:10.1158/1538-7445.AM2015-4292