Lactic Acid Permeability of Aquaporin-9 Enables Cytoplasmic Lactate Accumulation via an Ion Trap

(1) Background: Human aquaporin-9 (AQP9) conducts several small uncharged metabolites, such as glycerol, urea, and lactic acid. Certain brain tumors were shown to upregulate AQP9 expression, and the putative increase in lactic acid permeability was assigned to severity. (2) Methods: We expressed AQP9 and human monocarboxylate transporter 1 (MCT1) in yeast to determine the uptake rates and accumulation of radiolabeled l-lactate/l-lactic acid in different external pH conditions. (3) Results: The AQP9-mediated uptake of l-lactic acid was slow compared to MCT1 at neutral and slightly acidic pH, due to low concentrations of the neutral substrate species. At a pH corresponding to the pKa of l-lactic acid, uptake via AQP9 was faster than via MCT1. Substrate accumulation was fundamentally different between AQP9 and MCT1. With MCT1, an equilibrium was reached, at which the intracellular and extracellular l-lactate/H+ concentrations were balanced. Uptake via AQP9 was linear, theoretically yielding orders of magnitude of higher substrate accumulation than MCT1. (4) Conclusions: The selectivity of AQP9 for neutral l-lactic acid establishes an ion trap for l-lactate after dissociation. This may be physiologically relevant if the transmembrane proton gradient is steep, and AQP9 acts as the sole uptake path on at least one side of a polarized cell.

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669 Lactate uptake through MCT11, a novel monocarboxylate transporter, enforces dysfunction in terminally exhausted T cells

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.669 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A697-A697

Author(s):

Ronal Peralta ◽

Greg Delgoffe

Keyword(s):

T Cells ◽

Lactic Acid ◽

Tumor Burden ◽

B16 Melanoma ◽

T Cell Subsets ◽

Monocarboxylate Transporter ◽

Acid Uptake ◽

Ribonucleoprotein Complexes ◽

Lactate Uptake ◽

Marker Expression

BackgroundUpon infiltration into tumors, T cells experiencing persistent antigen stimulation progressively differentiate into a state of dysfunction, known as exhaustion. Exhausted T cells are characterized by the sustained upregulation of co-inhibitory molecules and reduced effector cytokine production. Additionally, exhausted T cells exist in a state of metabolic dysfunction in the tumor microenvironment (TME), due to disrupted mitochondrial biogenesis, hypoxia and lack of metabolites. Highly glycolytic tumor and stromal cells outcompete T cells for glucose, and secrete lactate into the TME, acidifying the extracellular space. Recent studies have shown lactate can be metabolized by tumor infiltrating Tregs and macrophages. We hypothesized that CD8+ tumor-infiltrating lymphocytes (TIL) may also take up lactate as an alternative carbon source to meet their metabolic demands.MethodsFor lactate uptake experiments, B16 melanoma single cell suspensions from B6 mice were loaded with the pH sensitive dye pHrodo, then pulsed with 5µM lactic acid. MCT11 KO OT-I T cells were generated via transfection of Slc16a11 sgRNA-Cas9 ribonucleoprotein complexes, and adoptively transferred into B16-OVA bearing mice.ResultsRNA sequencing and flow cytometry data from CD8+ T cell subsets in the TME revealed MCT11 (encoded by Slc16a11), a monocarboxylate transporter (MCT) only recently discovered, to be highly and uniquely expressed in terminally exhausted T cells (Tex). As lactate is an abundant monocarboxylate in tumors, we asked whether MCT11 supports lactate uptake into Tex cells. Antibody blockade of MCT11 resulted in reduced lactic acid uptake, but whether lactic acid promoted or inhibited effector function. Intriguingly, overexpression of MCT11 in OT-I T cells adoptively transferred into B16-OVA bearing mice resulted in accelerated exhaustion: increased co-inhibitory marker expression and decreased TNFa and IFN production. Conversely, knockdown of MCT11 in the same model resulted in decreased co-inhibitory marker expression and increased TNFa and IFN production. Further, MCT11 KO OT-I T cells used therapeutically had decreased tumor burden over mice treated with control OT-I T cells. As MCT11's uptake function was blocked with an antibody, we also used the antibody therapeutically, revealing that single-agent MCT11 antibody treatment reduced tumor burden and increased survival in B16 melanoma bearing mice.ConclusionsOur data support a model where exhausted CD8+ T cells upregulate MCT11, which renders them sensitive to toxic lactic acid in the TME. Our data suggest MCT11 could be deleted on therapeutic T cells or blocked using an antibody on endogenous T cells to render exhausted T cells impervious to lactic acid such and promote tumor eradication.

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Lactate transport by cardiac sarcolemmal vesicles

AJP Cell Physiology ◽

10.1152/ajpcell.1987.252.5.c483 ◽

1987 ◽

Vol 252 (5) ◽

pp. C483-C489 ◽

Cited By ~ 27

Author(s):

T. L. Trosper ◽

K. D. Philipson

Keyword(s):

Lactic Acid ◽

Monocarboxylate Transporter ◽

Disulfonic Acid ◽

Lactate Transport ◽

Monocarboxylic Acids ◽

Anion Transporter ◽

Ehrlich Ascites ◽

Internal Ph ◽

Sarcolemmal Vesicles ◽

External Ph

L-lactate is taken up by cardiac sarcolemmal vesicles in a process that is saturable with respect to L-lactate, stereospecific, associated specifically with the sarcolemmal membrane, and inhibited by other monocarboxylic acids and by the protein modifiers p-chloromercuriphenyl-sulfonate and N-ethylmaleimide. 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, an inhibitor of the inorganic anion transporter, is without effect. The L-lactate transport is very sensitive to pH. Uptake is stimulated by a proton gradient directed inward and decreased when internal pH is lower than external pH. Passive diffusion of nonionized lactic acid into the vesicles is negligible at physiological pH and appears to remain minor even when external pH is lowered by more than one unit. Also, the mechanism does not require specific Na+-L-lactate contransport. The properties of the L-lactate transporting system in cardiac sarcolemmal vesicles appear similar to those of the monocarboxylate transporter in erythrocytes, hepatocytes, and Ehrlich ascites cells. The present results do not allow a distinction to be made between stepwise interaction of lactate- and H+ or association of nonionized lactic acid with the carrier.

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The Effects of Physical Exertion According to the Monocarboxylate Transporter 1 (MCT1) on the Speed of Lactic Acid Elimination in Futsal Players

Soshum Jurnal Sosial dan Humaniora ◽

10.31940/soshum.v11i1.2129 ◽

2021 ◽

Vol 11 (1) ◽

pp. 80-87

Author(s):

Mustafa Jassim Abd Zaed ◽

◽

Shimal H. Hamad Chomani ◽

Marko Joksimovic ◽

◽

...

Keyword(s):

Genetic Diversity ◽

Lactic Acid ◽

Lactic Acid Production ◽

Physical Exertion ◽

Middle Level ◽

Monocarboxylate Transporter ◽

Monocarboxylate Transporter 1 ◽

Low Level ◽

Sports Club ◽

High Level

To identify the genetic diversity of futsal players in Al Hilla Sports Club for the season (2020-2021) after they were exposed to physical exertion by testing lactic mlss in the speed of recovery and elimination of lactic acid. The main experiment included two phases. The first is knowledge of the genetic diversity of the players. The first advanced level of this gene reached (5 players), the middle level (4 players), and the low level of the gene (3 players), and the second stage Of the experiment is to measure the searched variable (lactic acid) for all levels of the gene and to detect players who have a rapid elimination of lactic acid products. The experiment lasted for (2 months) and the most important conclusions were the high level of the MCT1 gene, the speed of elimination of lactic acid in the working muscles. There is a discrepancy between the hospitalization and the exercises. It appeared that the players who belong to this level have slow recovery Very compared to other levels, and this indicates that they are tired quickly. The players of this level have the advantage of quickly getting rid of lactic acid and recovering recovery compared to the low level, and they show less fatigue than the low level. The speed of elimination of lactic acid is less than the speed of its production, which facilitates the transfer of lactate from the working muscle to the blood and speed to get rid of it. Increasingly intense physical exertion affects the variation in the MCT1 gene level. The players at the high level of the MCT 1 gene showed an advantage in the speed of elimination of lactic acid production compared to the low and medium levels.

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Inhibitory effect of tumor cell–derived lactic acid on human T cells

Blood ◽

10.1182/blood-2006-07-035972 ◽

2007 ◽

Vol 109 (9) ◽

pp. 3812-3819 ◽

Cited By ~ 695

Author(s):

Karin Fischer ◽

Petra Hoffmann ◽

Simon Voelkl ◽

Norbert Meidenbauer ◽

Julia Ammer ◽

...

Keyword(s):

T Cells ◽

Lactic Acid ◽

Cytokine Production ◽

Lactic Acid Production ◽

Recovery Period ◽

Monocarboxylate Transporter ◽

Immune Functions ◽

Tumor Spheroids ◽

Activated T Cells ◽

Monocarboxylate Transporter 1

Abstract A characteristic feature of tumors is high production of lactic acid due to enhanced glycolysis. Here, we show a positive correlation between lactate serum levels and tumor burden in cancer patients and examine the influence of lactic acid on immune functions in vitro. Lactic acid suppressed the proliferation and cytokine production of human cytotoxic T lymphocytes (CTLs) up to 95% and led to a 50% decrease in cytotoxic activity. A 24-hour recovery period in lactic acid–free medium restored CTL function. CTLs infiltrating lactic acid–producing multicellular tumor spheroids showed a reduced cytokine production. Pretreatment of tumor spheroids with an inhibitor of lactic acid production prevented this effect. Activated T cells themselves use glycolysis and rely on the efficient secretion of lactic acid, as its intracellular accumulation disturbs their metabolism. Export by monocarboxylate transporter-1 (MCT-1) depends on a gradient between cytoplasmic and extracellular lactic acid concentrations and consequently, blockade of MCT-1 resulted in impaired CTL function. We conclude that high lactic acid concentrations in the tumor environment block lactic acid export in T cells, thereby disturbing their metabolism and function. These findings suggest that targeting this metabolic pathway in tumors is a promising strategy to enhance tumor immunogenicity.

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The inhibition of CD4 + T cell proinflammatory response by lactic acid is independent of Monocarboxylate transporter 1

Scandinavian Journal of Immunology ◽

10.1111/sji.13103 ◽

2021 ◽

Author(s):

Peng Yang ◽

Ying Sun ◽

Min Zhang ◽

Linhan Hu ◽

Xinwei Wang ◽

...

Keyword(s):

Lactic Acid ◽

T Cell ◽

Cd4 T Cell ◽

Monocarboxylate Transporter ◽

Proinflammatory Response ◽

Monocarboxylate Transporter 1

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Faculty Opinions recommendation of A novel nutrient sensing mechanism underlies substrate-induced regulation of monocarboxylate transporter-1.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717991560.793473364 ◽

2013 ◽

Author(s):

Bruno Stieger

Keyword(s):

Nutrient Sensing ◽

Monocarboxylate Transporter ◽

Monocarboxylate Transporter 1 ◽

Sensing Mechanism

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Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

Cardiovascular & Haematological Disorders - Drug Targets ◽

10.2174/1871529x18666180522073855 ◽

2019 ◽

Vol 19 (1) ◽

pp. 51-78 ◽

Cited By ~ 3

Author(s):

Ota Fuchs

Keyword(s):

Clinical Trials ◽

Transcription Factors ◽

Ubiquitin Ligase ◽

Mononuclear Cells ◽

E3 Ubiquitin Ligase ◽

Lymphocytic Leukemia ◽

Monocarboxylate Transporter ◽

Immunomodulatory Drugs ◽

Monocarboxylate Transporter 1 ◽

Argonaute 2

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

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Monocarboxylate transporter-1 (MCT1) protein expression in head and neck cancer affects clinical outcome

Scientific Reports ◽

10.1038/s41598-021-84019-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Martin Leu ◽

J. Kitz ◽

Y. Pilavakis ◽

S. Hakroush ◽

H. A. Wolff ◽

...

Keyword(s):

Cell Membrane ◽

Protein Expression ◽

Head And Neck ◽

Cox Regression ◽

Locally Advanced ◽

Monocarboxylate Transporter ◽

Positive Staining ◽

Monocarboxylate Transporter 1 ◽

Prognostic Features ◽

Hpv Status

AbstractTreatment of locally advanced, unresectable head and neck squamous cell carcinoma (HNSCC) often yields only modest results with radiochemotherapy (RCT) as standard of care. Prognostic features related to outcome upon RCT might be highly valuable to improve treatment. Monocarboxylate transporters-1 and -4 (MCT1/MCT4) were evaluated as potential biomarkers. A cohort of HNSCC patients without signs for distant metastases was assessed eliciting 82 individuals eligible whereof 90% were diagnosed with locally advanced stage IV. Tumor specimens were stained for MCT1 and MCT4 in the cell membrane by immunohistochemistry. Obtained data were evaluated with respect to overall (OS) and progression-free survival (PFS). Protein expression of MCT1 and MCT4 in cell membrane was detected in 16% and 85% of the tumors, respectively. Expression of both transporters was not statistically different according to the human papilloma virus (HPV) status. Positive staining for MCT1 (n = 13, negative in n = 69) strongly worsened PFS with a hazard ratio (HR) of 3.1 (95%-confidence interval 1.6–5.7, p < 0.001). OS was likewise affected with a HR of 3.8 (2.0–7.3, p < 0.001). Multivariable Cox regression confirmed these findings. We propose MCT1 as a promising biomarker in HNSCC treated by primary RCT.

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