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Immune-regulated IDO1-dependent tryptophan metabolism is source of one-carbon units for pancreatic cancer and stellate cells.

ABSTRACT: Cancer cells adapt their metabolism to support elevated energetic and anabolic demands of proliferation. Folate-dependent one-carbon metabolism is a critical metabolic process underpinning cellular proliferation supplying carbons for the synthesis of nucleotides incorporated into DNA and RNA. Recent research has focused on the nutrients that supply one-carbons to the folate cycle, particularly serine. Tryptophan is a theoretical source of one-carbon units through metabolism by IDO1, an enzyme intensively investigated in the context of tumor immune evasion. Using in vitro and in vivo pancreatic cancer models, we show that IDO1 expression is highly context dependent, influenced by attachment-independent growth and the canonical activator IFNγ. In IDO1-expressing cancer cells, tryptophan is a bona fide one-carbon donor for purine nucleotide synthesis in vitro and in vivo. Furthermore, we show that cancer cells release tryptophan-derived formate, which can be used by pancreatic stellate cells to support purine nucleotide synthesis.

SUBMITTER: Newman AC

PROVIDER: S-EPMC8189438 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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Immune-regulated IDO1-dependent tryptophan metabolism is source of one-carbon units for pancreatic cancer and stellate cells.

Newman Alice Clare AC Falcone Mattia M Huerta Uribe Alejandro A Zhang Tong T Athineos Dimitris D Pietzke Matthias M Vazquez Alexei A Blyth Karen K Maddocks Oliver David Kenneth ODK

Molecular cell 20210407 11

Cancer cells adapt their metabolism to support elevated energetic and anabolic demands of proliferation. Folate-dependent one-carbon metabolism is a critical metabolic process underpinning cellular proliferation supplying carbons for the synthesis of nucleotides incorporated into DNA and RNA. Recent research has focused on the nutrients that supply one-carbons to the folate cycle, particularly serine. Tryptophan is a theoretical source of one-carbon units through metabolism by IDO1, an enzyme in ...[more]

PMID: 33831358

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Project description:Abstract OBJECTIVE Glioblastoma (GBM) patients with high intratumoral IDO1 mRNA levels have an associated decrease in survival (Zhai et al., 2017; CCR). IDO1 is an immunosuppressive mediator that metabolizes tryptophan (Trp), and through its associated enzyme activity, has long been recognized to increase immunosuppressive CD4+CD25+FoxP3+ Tregs. Accordingly, we previously showed that the genetic knockdown of IDO1 in murine glioma cells, suppresses intratumoral Treg recruitment and increases animal subject survival. Unexpectedly, however, IDO1 knockdown has no effect on intratumoral Trp metabolism (Zhai et al., 2017; BBI). Further surprisingly, we recently demonstrated that, although IDO1 overexpression increases Treg levels in brain tumors, the pharmacological inhibition of IDO1 metabolism has no effect on Treg accumulation (Ladomersky et al., 2018; CCR). These novel data led us to question the requirement for IDO1 enzyme activity to regulate Tregs in malignant glioma. METHODS Lentiviral vectors encoding: (i) vector control-, (ii) wild-type (WT)-, or (iii) enzyme-null-IDO1, were created by site-directed mutagenesis in a plasmid containing WT, murine, IDO1-GFP cDNA. IDO1-deficient glioma cells from transgenic mice [(ERT2)GFAP→Cre;pTENfl/fl;p53fl/fl;Rbfl/fl;IDO1-/-] were transduced with the modified plasmids. RT-PCR, Western blotting and HPLC confirmed IDO1 expression and enzyme activity, in vitro. Syngeneic IDO1-/- mice were intracranially-engrafted with 2 × 105 modified glioma cells and studied for intratumoral Treg levels. RESULTS The substitution of IDO1 histidine 350, to an alanine (H350A), decreases IDO1 enzyme activity by 90%. Syngeneic mice with intracranial, IDO1 enzyme null (H350A) glioma, have similar intratumoral Treg levels as IDO1 WT glioma, at 25% and 26%, respectively, and is significantly increased as compared to the 5.8% Tregs in vector control glioma (P=0.015). CONCLUSIONS Our data challenge current dogma explaining how IDO1 causes Treg accumulation, and are in-line with the recent IDO1 enzyme inhibitor-focused Phase III clinical trial failure [NCT02752074]. We are now focused on revealing the mechanism underlying IDO1-mediated immunosuppression in malignant glioma.

Project description:BackgroundPancreatic ductal adenocarcinoma (PDAC) is the most lethal malignancy: it has a 5-year survival rate of less than 9%. Although surgical resection is an effective treatment for PDAC, only a small number of patients can have their tumors surgically removed. Thus, an urgent need to find new therapeutic targets for PDAC exists. Understanding the molecular mechanism of PDAC development is essential for the treatment of this malignancy. This research aimed to study the mechanisms of pancreatic stellate cells (PSCs), which regulate branched-chain amino acid (BCAA) metabolism in PDAC.MethodsDifferentially expressed proteins were detected via nanoliquid chromatography coupled to mass spectrometry (nano-LC-MS/MS). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment methods were used to find the valine-leucine-isoleucine (BCAA) degradation pathway. The levels of BCAAs in the sera and tissues of patients with PDAC were measured by using nuclear magnetic resonance (NMR). The functions of BCAA concentrations and the effects of activated pancreatic stellate cells (aPSCs) were also evaluated by performing Cell Counting Kit-8, colony formation, and wound healing assays.ResultsA total of 1,519 proteins with significantly differential expression were discovered in PDAC and adjacent tissues by using nano-LC-MS/MS. KEGG pathway enrichment analysis identified the BCAA degradation pathway. The content of BCAA in PDAC clinical samples was up-regulated. However, the addition of different concentrations of BCAA to PDAC cell culture medium failed to promote the proliferation and migration of PDAC cells. Given that analysis based on The Cancer Genome Atlas database showed that the number of aPSCs gradually increased with the progression of PDAC, the effects of aPSCs on PDAC cells were explored. After coculture with aPSCs, PDAC cell proliferation showed a significant increase, and the proteins involved in the BCAA degradation pathway in PDAC cells had also changed.ConclusionsaPSCs could regulate BCAA metabolism to enhance the progression of PDAC, indicating that the regulation of BCAA metabolism may serve as a new therapeutic direction for PDAC.

Project description:BackgroundLow chronic vitamin B-6 status can occur in a subset of women who use oral contraceptives (OCs) with uncertain metabolic consequences. An insufficiency of cellular pyridoxal 5'-phosphate (PLP), which is the coenzyme form of vitamin B-6, may impair many metabolic processes including one-carbon and tryptophan metabolism.ObjectiveWe investigated the effects of vitamin B-6 supplementation on the in vivo kinetics of one-carbon metabolism and the concentration of one-carbon and tryptophan metabolites in vitamin B-6-deficient OC users.DesignA primed, constant infusion of [(13)C5]methionine, [3-(13)C]serine, and [(2)H3]leucine was performed on 10 OC users (20-40 y old; plasma PLP concentrations <30 nmol/L) before and after 28 d of supplementation with 10 mg pyridoxine hydrochloric acid/d. In vivo fluxes of total homocysteine remethylation, the remethylation of homocysteine from serine, and rates of homocysteine and cystathionine production were assessed. Targeted metabolite profiling was performed, and data were analyzed by using orthogonal partial least-squares-discriminant analysis and paired t tests adjusted for multiple testing.ResultsPyridoxine supplementation increased the mean ± SD plasma PLP concentration from 25.8 ± 3.6 to 143 ± 58 nmol/L (P < 0.001) and decreased the leucine concentration from 103 ± 17 to 90 ± 20 nmol/L (P = 0.007) and glycine concentration from 317 ± 63 to 267 ± 58 nmol/L (P = 0.03). Supplementation did not affect in vivo rates of homocysteine remethylation or the appearance of homocysteine and cystathionine. A multivariate analysis showed a clear overall effect on metabolite profiles resulting from supplementation. Leucine, glycine, choline, cysteine, glutathione, trimethylamine N-oxide, and the ratios glycine:serine, 3-hydroxykynurenine:kynurenine, 3-hydroxykynurenine:3-hydroxyanthranilic acid, and 3-hydroxykynurenine:anthranilic acid were significant discriminating variables.ConclusionsConsistent with previous vitamin B-6-restriction studies, fluxes of one-carbon metabolic processes exhibited little or no change after supplementation in low-vitamin B-6 subjects. In contrast, changes in the metabolic profiles after supplementation indicated perturbations in metabolism, suggesting functional vitamin B-6 deficiency. This study was registered at clinicaltrials.gov as NCT01128244.

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Immune-regulated IDO1-dependent tryptophan metabolism is source of one-carbon units for pancreatic cancer and stellate cells.

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Immune-regulated IDO1-dependent tryptophan metabolism is source of one-carbon units for pancreatic cancer and stellate cells.

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