Development of inhibitors of lactate transport as an anticancer strategy : chemical synthesis, in vitro functional screening and in vivo therapeutic validation

Proliferating cancer cells consume glucose at a high rate and release lactate. This adaptive metabolism provides tumor cells with ATP as an energy source but also with major anabolic intermediates. In addition, lactate can stimulate angiogenesis and when re-captured by oxidative cancer cells can feed the TCA cycle after reconversion into pyruvate. Monocarboxylate transporters (MCT)therefore represent potential therapeutic targets to limit tumor progression. Rational design and pharmacomodulation led us to identify 7-aminocarboxycoumarins (7ACC) as a scaffold endowed with inhibitory effects on lactate transport. We first compared the cytotoxic potential of our compounds in either glucose- or lactate-containing medium. This primary assay led us to identify hits that inhibited cell proliferation in lactate conditions but failed to exert toxic effects in the glucose condition. The secondary assay confirmed that our hits functionally block lactate influx. In a third assay based on the measurement of [14C]-lactate uptake in minute-range periods, we validated our hits as bona fide inhibitors of lactate influx through either MCT1 or MCT4. In vivo proof of principle of the antitumor effects of 7ACC, showing a favorable pharmacokinetic profile, was obtained in nude mice bearing human breast, cervix, bladder and colorectal cancers. 7ACC compounds consistently led to significant tumor growth delays except for bladder tumors in adequation with the lack of MCT1/4 expression in these tumors. Antitumor effects were further increased when 7ACC were combined with conventional chemotherapy or radiotherapy. Altogether, these results confirm the rationale to interfere with lactate transport in tumors and validate a new family of MCT inhibitors as an efficient anticancer strategy.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 201

Lactate shuttles at a glance: from physiological paradigms to anti-cancer treatments.

Hypoxia and oncogene expression both stimulate glycolytic metabolism in tumors, thereby leading to lactate production. However, lactate is more than merely a by-product of glycolysis: it can be used as a metabolic fuel by oxidative cancer cells. This phenomenon resembles processes that have been described for skeletal muscle and brain that involve what are known as cell-cell and intracellular lactate shuttles. Two control points regulate lactate shuttles: the lactate dehydrogenase (LDH)-dependent conversion of lactate into pyruvate (and back), and the transport of lactate into and out of cells through specific monocarboxylate transporters (MCTs). In tumors, MCT4 is largely involved in hypoxia-driven lactate release, whereas the uptake of lactate into both tumor cells and tumor endothelial cells occurs via MCT1. Translating knowledge of lactate shuttles to the cancer field offers new perspectives to therapeutically target the hypoxic tumor microenvironment and to tackle tumor angiogenesis

Endothelial cell metabolism: an update anno 2017

Endothelial cell metabolism has recently emerged as an important coregulator of angiogenesis and is therefore a promising new target in various angiogenesis-associated illnesses, like cancer. In this review, we discuss recent insights in endothelial cell metabolism in both physiological and pathological conditions and discuss possible translational implications.status: publishe

One-pot synthesis and in vitro antitumor activity of some bipyrazolic tripodal derivatives

The synthesis and structure-activity relationships (SAR) antitumor activities of monopyrazolic and bipyrazolic tripodal derivs. were reported here for the first time. The ten products were tested against three human cancer cell lines including breast (MDA-MB231), prostate (PC3) and colorectal (LoVo) cancers. In bipyrazolic series, most of them exhibited a moderate antitumor activity against three human cancer cell lines with an order of 5 > 7 > 8 in case of colorectal cancer and 5 > 7 ≈ 8 in case of breast and prostate cancers

Search for monoglyceride lipase inhibitors : synthesis and screening of arylthioamides derivatives

Monoglyceride lipase (MGL) is the enzyme responsible for the termination of 2-arachidonoylglycerol (2-AG) signalling, an endogenous ligand for the G-protein coupled cannabinoid receptors CB1 and CB2. Its known abundance and physiological roles emphasize the interest of MGL as an attractive therapeutic target. Search for MGL inhibitors was undertaken by screening an arylthioamide series. The evaluation of arylthioamides derivatives activity as MGL inhibitors measured by the hydrolysis of [H-3]-2-oleoylglycerol by human purified MGL led to the identification of (2-chloro-phenyl)-morpholin-4-yl-methanethione (2) and (3-nitro-phenyl) morpholin-4-yl-methanethione (12), which moreover exhibit good selectivity compared with human fatty acid amide hydrolase inhibition

The SIRT1/HIF2α Axis Drives Reductive Glutamine Metabolism under Chronic Acidosis and Alters Tumor Response to Therapy.

Extracellular tumor acidosis largely results from an exacerbated glycolytic flux in cancer and cancer-associated cells. Conversely, little is known about how tumor cells adapt their metabolism to acidosis. Here, we demonstrate that long-term exposure of cancer cells to acidic pH leads to a metabolic reprogramming toward glutamine metabolism. This switch is triggered by the need to reduce the production of protons from glycolysis and further maintained by the NAD(+)-dependent increase in SIRT1 deacetylase activity to ensure intracellular pH homeostasis. A consecutive increase in HIF2α activity promotes the expression of various transporters and enzymes supporting the reductive and oxidative glutamine metabolism, whereas a reduction in functional HIF1α expression consolidates the inhibition of glycolysis. Finally, in vitro and in vivo experiments document that acidosis accounts for a net increase in tumor sensitivity to inhibitors of SIRT1 and glutaminase GLS1. These findings highlight the influence that tumor acidosis and metabolism exert on each other. Cancer Res; 74(19); 1-13. ©2014 AACR

Antitumor activity of 7-aminocarboxycoumarin derivatives, a new class of potent inhibitors of lactate influx but not efflux.

High lactate concentration in tumors is associated with bad prognosis. Lactate is released by glycolytic cells in tumors and recaptured by oxidative cancer cells to feed the tricarboxylic acid (TCA) cycle after conversion into pyruvate. Monocarboxylate transporters (MCT) mediate these fluxes of proton-linked lactate and represent attractive targets to interrupt lactate shuttle and to inhibit tumor growth. Here, we investigated the properties of 7-aminocarboxycoumarins (7ACC) developed to selectively interfere with lactate fluxes in the lactate-rich tumor microenvironment. The pharmacologic properties of two compounds of this family, including their effects on lactate influx and efflux and antitumor activity, were investigated using human cancer cell lines and mouse xenograft models. Contrary to the reference MCT1 inhibitor AR-C155858, 7ACC unexpectedly inhibited lactate influx but not efflux in tumor cells expressing MCT1 and MCT4 transporters. 7ACC delayed the growth of cervix SiHa tumors, colorectal HCT116 tumors, and orthoptopic MCF-7 breast tumors. MCT target engagement was confirmed by the lack of activity of 7ACC on bladder UM-UC-3 carcinoma that does not express functional MCT. 7ACC also inhibited SiHa tumor relapse after treatment with cisplatin. Finally, we found that contrary to AR-C155858, 7ACC did not prevent the cell entry of the substrate-mimetic drug 3-bromopyruvate (3BP) through MCT1, and contributed to the inhibition of tumor relapse after 3BP treatment. In conclusion, our results indicate that 7ACC selectively affects a single part of the MCT symporter translocation cycle, leading to strict inhibition of lactate influx. This singular activity is associated with antitumor effects less prone to resistance and side effects. Mol Cancer Ther; 13(6); 1410-8. ©2014 AACR

Metabolic adaptation of tumor cells under chronic acidosis: a shift towards reductive glutamine metabolism driven by the SIRT1/HIF2 axis

Cancer progression is strongly influenced by the physico-chemical properties of the tumor microenvironment. In particular, tumor cells must adapt to survive under low pO2 and low pH. Although the impact of hypoxia on tumor metabolism is well described, little is known on how tumor cells adapt their metabolism to acidosis. Here, we exposed tumor cells derived from various tissues to low pH conditions (pH 6.5) for several weeks until they ended up proliferating at the same rate as parent cells maintained at pH 7.4. This low pH acclimation triggered the reprogramming of tumor cells from a mainly glycolytic metabolism towards the preferred use of glutamine as documented by tracking the fate of [U-13C] glucose and [U-13C] glutamine by GC-MS analysis of metabolites. The metabolic switch was mediated by SIRT1, a protein deacetylase activated by the increased pool of NAD+ in low pH-adapted cells, through two distinct mechanisms. First, free acetate acted as a counteranion to export excess protons out of the cells via MCT1, maintaining the intracellular pH in a physiological range. Second, SIRT1 stimulated the activity of HIF2 thereby supporting the glutamine metabolism via the upregulation of the glutamine transporter SLC1A5 and enzymes supporting the reductive glutamine metabolism including IDH1. Finally, pharmacological inhibition of either glutamine metabolism with the glutaminase inhibitor BPTES or SIRT1 deacetylase activity preferentially killed low pH-adapted cancer cells in vitro (vs. parent cells) and delayed the growth of corresponding tumor xenografts in vivo. Altogether, these data indicate that a major metabolic shift from glucose to glutamine metabolism is induced in tumor cells chronically exposed to an acidic environment and importantly makes them particularly suited for dedicated pharmacological treatments

Sirtuin 1 mediates acidosis-induced metabolic reprogramming of tumor cells

Mechanisms underlying cancer progression are strongly influenced by the physico-chemical properties of the tumor microenvironment. In particular, tumor cells must adapt to survive under low pO2 and low pH. Although the impact of hypoxia on tumor metabolism is well described, the influence of extracellular acidosis on the metabolic preferences of cancer cells is largely unknown. Still, tumor acidosis is known to affect important energy-consuming cellular functions including proliferation and invasion. In this study, we have therefore exposed tumor cells (derived from various tissues) to low pH conditions (pH 6.5) for several weeks. After acidic acclimation, we found that tumor cells proliferate at the same rate as parent cells maintained at pH 7.4. More interestingly, we documented that chronic low pH exposure triggers the metabolic reprogramming of tumor cells from the preferential use of glucose towards glutamine metabolism. The use of glutamine as a major fuel of the TCA cycle in low pH-adapted tumor cells was proven using a variety of techniques including measurement of [U13C5]-glutamine incorporation in metabolites (determined by GC-MS) and determination of the oxygen consumption rate (OCR) using a Seahorse microplate analyser. Mechanistic dissection of the low pH-driven phenotype led us to document that the metabolic switch was mediated by SIRT1, a NAD+-dependent protein deacetylase. We actually found that at acidic pH, SIRT1 promotes glutamine metabolism in a HIF2-dependent manner. By contrast, we observed a SIRT-1-mediated decrease in HIF1 signalling and associated glycolysis. These observations were repeated with the exact same conclusions using tumor cell lines of various origins (cervix SiHa, pharynx FaDu and colon HCT116). Also, the 'glutamine-addicted' phenotype was proven to be reversible when acclimated cells were again cultured under physiological pH, thereby excluding a clonal selection of tumor cells in response to the acidic conditions. Finally, pharmacological inhibition of either glutamine metabolism (using the glutaminase inhibitor BPTES) or SIRT1 deacetylase activity preferentially killed low pH-adapted cancer cells in vitro (vs. parent cells) and delayed the growth of corresponding tumor xenografts in vivo. Altogether, these observations indicate that a major metabolic shift from glucose to glutamine metabolism is induced in tumor cells chronically exposed to an acidic environment and importantly makes them particularly suited for dedicated pharmacological treatments