Activated immune cells undergo a metabolic switch to aerobic glycolysis akin to the Warburg effect, presenting a potential therapeutic target in autoimmune disease. Dimethyl fumarate, a derivative of the Krebs cycle intermediate fumarate, is an immunomodulatory drug used to treat multiple sclerosis and psoriasis. Although its therapeutic mechanism remains uncertain, it covalently modifies cysteine residues in a process termed “succination.” Here, we show that dimethyl fumarate succinates and inactivates the catalytic cysteine of the glycolytic enzyme GAPDH both in vitro and in vivo. It thereby downregulates aerobic glycolysis in activated myeloid and lymphoid cells, which mediates its anti-inflammatory effects. Our findings provide mechanistic insight into immune modulation by dimethyl fumarate and represent a proof of concept that aerobic glycolysis is a therapeutic target in autoimmunity.

Metabolic profiling of cancer cells has recently been established as a promising tool for the development of therapies and identification of cancer biomarkers.Here we characterized the metabolomic profile of human breast tumors and uncovered intrinsic metabolite signatures in these tumors using an untargeted discovery approach and validation of key metabolites. The oncometabolite 2-hydroxyglutarate (2HG) accumulated at high levels in a subset of tumors and human breast cancer cell lines. We discovered an association between increased 2HG levels and MYC pathway activation in breast cancer, and further corroborated this relationship using MYC overexpression and knockdown in human mammary epithelial and breast cancer cells. Further analyses revealed globally increased DNA methylation in 2HG-high tumors and identified a tumor subtype with high tissue 2HG and a distinct DNA methylation pattern that was associated with poor prognosis and occurred with higher frequency in African-American patients. Tumors of this subtype had a stem cell-like transcriptional signature and tended to overexpress glutaminase, suggestive of a functional relationship between glutamine and 2HG metabolism in breast cancer. Accordingly, 13C-labeled glutamine was incorporated into 2HG in cells with aberrant 2HG accumulation, whereas pharmacologic and siRNAmediated glutaminase inhibition reduced 2HG levels. Our findings implicate 2HG as a candidate breast cancer oncometabolite associated with MYC activation and poor prognosis.

The mechanisms through which tumor cells genetically lose antigenicity and evade immune checkpoints remain largely elusive. Here, we report that tissue-specific expression of the human long-noncoding RNA LINK-A in mouse mammary glands initiated metastatic mammary gland tumors, which phenotypically resembled human triple-negative breast cancer (TNBC). LINK-A expression facilitated crosstalk between phosphatidylinositol-(3,4,5)-trisphosphate and inhibitory G-protein–coupled receptor (GPCR) pathways, attenuating protein kinase A (PKA)-mediated phosphorylation of the E3 ubiquitin ligase TRIM71. Consequently, LINK-A expression enhanced K48–polyubiquitination-mediated degradation of the antigen peptide-loading complex (PLC) and intrinsic tumor suppressors Rb and p53. Treatment with LINK-A-locked nucleic acids or GPCR antagonists stabilized the PLC components, Rb, and p53, and sensitized mammary gland tumors to immune checkpoint blockers (ICBs). Importantly, PD-1 blockade-resistant TNBC patients exhibited elevated LINK-A levels and downregulated PLC components. Hence, we demonstrated lncRNA-dependent downregulation of antigenicity and intrinsic tumor suppression, which may provide the basis for developing a therapeutic regimen of combinational immunotherapy and effective early prevention for TNBCs.

Summary Transmitochondrial cybrids and multiple OMICs approaches were used to understand mitochondrial reprogramming and mitochondria-regulated cancer pathways in triple negative breast cancer (TNBC). Analysis of cybrids and established breast cancer (BC) cell lines showed that metastatic TNBC maintains high levels of ATP through fatty acid β-oxidation (FAO) and activates Src oncoprotein through autophosphorylation at Y419. Manipulation of FAO including the knocking down of carnitine palmitoyltransferase-1 (CPT1) and 2 (CPT2), the rate-limiting proteins of FAO, and analysis of patient-derived xenograft models, confirmed the role of mitochondrial FAO in Src activation and metastasis. Analysis of TCGA and other independent BC clinical data further reaffirmed the role of mitochondrial FAO and CPT genes in Src regulation and their significance in BC metastasis.

While alterations in xenobiotic metabolism are considered causal in the development of bladder cancer (BCa), the precise mechanisms involved are poorly understood. In this study, we used high-throughput mass spectrometry to measure over 2,000 compounds in 58 clinical specimens, identifying 35 metabolites which exhibited significant changes in BCa. This metabolic signature distinguished both normal and benign bladder from BCa. Exploratory analyses of this metabolomic signature in urine showed promise in distinguishing BCa from controls, and also non-muscle from muscle-invasive BCa. Subsequent enrichment-based bioprocess mapping revealed alterations in phase I/II metabolism and suggested a possible role for DNA methylation in perturbing xenobiotic metabolism in BCa. In particular, we validated tumor-associated hypermethylation in the CYP1A1 and CYP1B1 promoters of BCa tissues by bisulfite sequence analysis and methylation-specific PCR, and also by in vitro treatment of T-24 BCa cell line with the DNA demethylating agent 5-aza-2′-deoxycytidine. Further, we showed that expression of CYP1A1 and CYP1B1 was reduced significantly in an independent cohort of BCa specimens compared to matched benign adjacent tissues. In summary, our findings identified candidate diagnostic and prognostic markers and highlighted mechanisms associated with the silencing of xenobiotic metabolism. The metabolomic signature we describe offers potential as a urinary biomarker for early detection and staging of BCa, highlighting the utility of evaluating metabolomic profiles of cancer to gain insights into bioprocesses perturbed during tumor development and progression.