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Euglycemic diabetic ketoacidosis is a metabolic condition characterized by relative euglycemia, ketonemia, and metabolic acidosis that occurs through mechanisms resembling starvation. Pancreaticoduodenectomy is a complex abdominal operation that subjects patients to a prolonged fasting and an inflammatory state. This study examined the incidence of euglycemic diabetic ketoacidosis and potential opportunities for early diagnosis and management in patients undergoing pancreaticoduodenectomy.A single-institution retrospective review of 350 patients who underwent pancreaticoduodenectomy between 2017 and 2020 was performed. Primary endpoints were peak beta-hydroxybutyrate levels, peak lactate levels, lowest pH, peak base deficits, and urinary output within the first 24 hours, postoperatively. Additional endpoints included incidence of postoperative pancreatic fistula, delayed gastric emptying, total complications, postoperative hospital length of stay, readmission rates, and changes in insulin regimen at discharge.Of the 350 cases reviewed, 39 (11.1%) patients developed euglycemic diabetic ketoacidosis. Male sex and pancreatic cancer were associated with a risk for euglycemic diabetic ketoacidosis (P.05). Patients with euglycemic diabetic ketoacidosis had significantly higher peak beta-hydroxybutyrate levels than patients without euglycemic diabetic ketoacidosis (mean difference = 19.8 mg/dL, 95% confidence interval = 14.7-24.9, P.001), and were nearly four times more likely to require insulin at discharge (odds ratio 3.8, 95% confidence interval = 1.1-13.0, P.05).This is the first large descriptive study that investigates euglycemic diabetic ketoacidosis after pancreaticoduodenectomy. Euglycemic diabetic ketoacidosis after pancreaticoduodenectomy is associated with significantly higher beta-hydroxybutyrate levels and new or increased insulin requirement at discharge. Our study demonstrates potential markers for euglycemic diabetic ketoacidosis after pancreaticoduodenectomy, offering an opportunity to identify and successfully treat this disease in a timely manner.

[18F]FCH uptake in TSC2-deficient cells in vivo after 72-hr exposure to vehicle control (two representative mice).

mTOR signaling in human TSC2-deficient cells versus TSC2 add-back cells

Impact of LPA and S1P on the transcriptome and proliferation of human TSC2-deficient cells treated with GLPG1690

LPAR and S1PR expression in human TSC2-deficient cells

Expression of lipogenic enzymes in human TSC2-deficient and TSC2 add-back cells treated with GLPG1690

GLPG1690 treatment inhibits the proliferation of Tsc2-/- MEFs in vitro

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by multiorgan hamartomas, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). TSC2 deficiency leads to hyperactivation of mTOR Complex 1 (mTORC1), a master regulator of cell growth and metabolism. Phospholipid metabolism is dysregulated upon TSC2 loss, causing enhanced production of lysophosphatidylcholine (LPC) species by TSC2-deficient tumor cells. LPC is the major substrate of the secreted lysophospholipase D autotaxin (ATX), which generates two bioactive lipids, lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P). We report here that ATX expression is upregulated in human renal angiomyolipoma-derived TSC2-deficient cells compared with TSC2 add-back cells. Inhibition of ATX via the clinically developed compound GLPG1690 suppressed TSC2-loss associated oncogenicity in vitro and in vivo and induced apoptosis in TSC2-deficient cells. GLPG1690 suppressed AKT and ERK1/2 signaling and profoundly impacted the transcriptome of these cells while inducing minor gene expression changes in TSC2 add-back cells. RNA-sequencing studies revealed transcriptomic signatures of LPA and S1P, suggesting an LPA/S1P-mediated reprogramming of the TSC lipidome. In addition, supplementation of LPA or S1P rescued proliferation and viability, neutral lipid content, and AKT or ERK1/2 signaling in human TSC2-deficient cells treated with GLPG1690. Importantly, TSC-associated renal angiomyolipomas have higher expression of LPA receptor 1 and S1P receptor 3 compared with normal kidney. These studies increase our understanding of TSC2-deficient cell metabolism, leading to novel potential therapeutic opportunities for TSC and LAM.Significance:This study identifies activation of the ATX–LPA/S1P pathway as a novel mode of metabolic dysregulation upon TSC2 loss, highlighting critical roles for ATX in TSC2-deficient cell fitness and in TSC tumorigenesis.

Summary of FCH and FACE Imaging

Supplementary Methods and Supplementary Figure legends

Human P-Kinase array reveals changes in Akt and Erk signaling in human TSC2-deficient cells treated with GLPG1690

Background: BRAFV600E acts as an ATP-dependent cytosolic kinase. BRAFV600E inhibitors are widely available, but resistance to them is widely reported in the clinic. Lipid metabolism (fatty acids) i...

Background: BRAF(V600E) acts as an ATP-dependent cytosolic kinase. BRAF(V600E) inhibitors are widely available, but resistance to them is widely reported in the clinic. Lipid metabolism (fatty acids) is fundamental for energy and to control cell stress. Whether and how BRAF(V600E) impacts lipid metabolism regulation in papillary thyroid carcinoma (PTC) is still unknown. Acetyl-CoA carboxylase (ACC) is a rate-limiting enzyme for de novo lipid synthesis and inhibition of fatty acid oxidation (FAO). ACC1 and ACC2 genes encode distinct isoforms of ACC. The aim of our study was to determine the relationship between BRAF(V600E) and ACC in PTC. Methods: We performed RNA-seq and DNA copy number analyses in PTC and normal thyroid (NT) in The Cancer Genome Atlas samples. Validations were performed by using assays on PTC-derived cell lines of differing BRAF status and a xenograft mouse model derived from a heterozygous BRAF(WT/V600E) PTC-derived cell line with knockdown (sh) of ACC1 or ACC2. Results: ACC2 mRNA expression was significantly downregulated in BRAF(V600E)-PTC vs. BRAF(WT)-PTC or NT clinical samples. ACC2 protein levels were downregulated in BRAF(V600E)-PTC cell lines vs. the BRAF(WT/WT) PTC cell line. Vemurafenib increased ACC2 (and to a lesser extent ACC1) mRNA levels in PTC-derived cell lines in a BRAF(V600E) allelic dose-dependent manner. BRAF(V600E) inhibition increased de novo lipid synthesis rates, and decreased FAO due to oxygen consumption rate (OCR), and extracellular acidification rate (ECAR), after addition of palmitate. Only shACC2 significantly increased OCR rates due to FAO, while it decreased ECAR in BRAF(V600E) PTC-derived cells vs. controls. BRAF(V600E) inhibition synergized with shACC2 to increase intracellular reactive oxygen species production, leading to increased cell proliferation and, ultimately, vemurafenib resistance. Mice implanted with a BRAF(WT/V600E) PTC-derived cell line with shACC2 showed significantly increased tumor growth after vemurafenib treatment, while vehicle-treated controls, or shGFP control cells treated with vemurafenib showed stable tumor growth. Conclusions: These findings suggest a potential link between BRAF(V600E) and lipid metabolism regulation in PTC. BRAF(V600E) downregulates ACC2 levels, which deregulates de novo lipid synthesis, FAO due to OCR, and ECAR rates. ShACC2 may contribute to vemurafenib resistance and increased tumor growth. ACC2 rescue may represent a novel molecular strategy for overcoming resistance to BRAF(V600E) inhibitors in refractory PTC.

p62/sequestosome-1 (SQSTM1) is a multifunctional adaptor protein and autophagic substrate that accumulates in cells with hyperactive mTORC1, such as kidney cells with mutations in the tumor suppressor genes tuberous sclerosis complex (TSC)1 or TSC2. Here we report that p62 is a critical mediator of TSC2-driven tumorigenesis, as Tsc2+/− and Tsc2f/f CAGGCreERT2+ mice crossed to p62−/− mice were protected from renal tumor development. Metabolic profiling revealed that depletion of p62 in Tsc2-null cells decreased intracellular glutamine, glutamate, and glutathione (GSH). p62 positively regulated the glutamine transporter Slc1a5 and increased glutamine uptake in Tsc2-null cells. We also observed p62-dependent changes in Gcl, Gsr, Nqo1, and Srxn1, which were decreased by p62 attenuation and implicated in GSH production and utilization. p62 attenuation altered mitochondrial morphology, reduced mitochondrial membrane polarization and maximal respiration, and increased mitochondrial reactive oxygen species and mitophagy marker PINK1. These mitochondrial phenotypes were rescued by addition of exogenous GSH and overexpression of Sod2, which suppressed indices of mitochondrial damage and promoted growth of Tsc2-null cells. Finally, p62 depletion sensitized Tsc2-null cells to both oxidative stress and direct inhibition of GSH biosynthesis by buthionine sulfoximine. Our findings show how p62 helps maintain intracellular pools of GSH needed to limit mitochondrial dysfunction in tumor cells with elevated mTORC1, highlighting p62 and redox homeostasis as nodal vulnerabilities for therapeutic targeting in these tumors. Cancer Res; 77(12); 3255–67. ©2017 AACR.

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by multiorgan hamartomas, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). TSC2 deficiency leads to hyperactivation of mTOR Complex 1 (mTORC1), a master regulator of cell growth and metabolism. Phospholipid metabolism is dysregulated upon TSC2 loss, causing enhanced production of lysophosphatidylcholine (LPC) species by TSC2-deficient tumor cells. LPC is the major substrate of the secreted lysophospholipase D autotaxin (ATX), which generates two bioactive lipids, lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P). We report here that ATX expression is upregulated in human renal angiomyolipoma-derived TSC2-deficient cells compared with TSC2 add-back cells. Inhibition of ATX via the clinically developed compound GLPG1690 suppressed TSC2-loss associated oncogenicity in vitro and in vivo and induced apoptosis in TSC2-deficient cells. GLPG1690 suppressed AKT and ERK1/2 signaling and profoundly impacted the transcriptome of these cells while inducing minor gene expression changes in TSC2 add-back cells. RNA-sequencing studies revealed transcriptomic signatures of LPA and S1P, suggesting an LPA/S1P-mediated reprogramming of the TSC lipidome. In addition, supplementation of LPA or S1P rescued proliferation and viability, neutral lipid content, and AKT or ERK1/2 signaling in human TSC2-deficient cells treated with GLPG1690. Importantly, TSC-associated renal angiomyolipomas have higher expression of LPA receptor 1 and S1P receptor 3 compared with normal kidney. These studies increase our understanding of TSC2-deficient cell metabolism, leading to novel potential therapeutic opportunities for TSC and LAM. Significance: This study identifies activation of the ATX–LPA/S1P pathway as a novel mode of metabolic dysregulation upon TSC2 loss, highlighting critical roles for ATX in TSC2-deficient cell fitness and in TSC tumorigenesis.

Purpose: Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by inactivating mutations of the TSC1 or TSC2 gene, characterized by neurocognitive impairment and benign tumors of the brain, skin, heart, and kidneys. Lymphangioleiomyomatosis (LAM) is a diffuse proliferation of α-smooth muscle actin–positive cells associated with cystic destruction of the lung. LAM occurs almost exclusively in women, as a TSC manifestation or a sporadic disorder (TSC1/TSC2 somatic mutations). Biomarkers of whole-body tumor burden/activity and response to rapalogs or other therapies remain needed in TSC/LAM. Experimental Design: These preclinical studies aimed to assess feasibility of [18F]fluorocholine (FCH) and [18F]fluoroacetate (FACE) as TSC/LAM metabolic imaging biomarkers. Results: We previously reported that TSC2-deficient cells enhance phosphatidylcholine synthesis via the Kennedy pathway. Here, we show that TSC2-deficient cells exhibit rapid uptake of [18F]FCH in vivo and can be visualized by PET imaging in preclinical models of TSC/LAM, including subcutaneous tumors and pulmonary nodules. Treatment with rapamycin (72 hours) suppressed [18F]FCH standardized uptake value (SUV) by >50% in tumors. Interestingly, [18F]FCH-PET imaging of TSC2-deficient xenografts in ovariectomized mice also showed a significant decrease in tumor SUV. Finally, we found rapamycin-insensitive uptake of FACE by TSC2-deficient cells in vitro and in vivo, reflecting its mitochondrial accumulation via inhibition of aconitase, a TCA cycle enzyme. Conclusions: Preclinical models of TSC2 deficiency represent informative platforms to identify tracers of potential clinical interest. Our findings provide mechanistic evidence for testing the potential of [18F]FCH and [18F]FACE as metabolic imaging biomarkers for TSC and LAM proliferative lesions, and novel insights into the metabolic reprogramming of TSC tumors.

Chromophobe renal cell carcinoma (ChRCC) accounts for 5% of all sporadic renal cancers and can also occur in genetic syndromes including Birt-Hogg-Dube (BHD) and tuberous sclerosis complex (TSC). ChRCC has a distinct accumulation of abnormal mitochondria, accompanied by characteristic chromosomal imbalances and relatively few "driver" mutations. Metabolomic profiling of ChRCC and oncocytomas (benign renal tumors that share pathological features with ChRCC) revealed both similarities and differences between these tumor types, with principal component analysis (PCA) showing a distinct separation. ChRCC have a striking decrease in intermediates of the glutathione salvage pathway (also known as the gamma-glutamyl cycle) compared with adjacent normal kidney, as well as significant changes in glycolytic and pentose phosphate pathway intermediates. We also found that gamma glutamyl transferase 1 (GGT1), the key enzyme of the gamma-glutamyl cycle, is expressed at ∼100-fold lower levels in ChRCC compared with normal kidney, while no change in GGT1 expression was found in clear cell RCC (ccRCC). Significant differences in specific metabolite abundance were found in ChRCC vs. ccRCC, including the oxidative stress marker ophthalmate. Down-regulation of GGT1 enhanced the sensitivity to oxidative stress and treatment with buthionine sulfoximine (BSO), which was associated with changes in glutathione-pathway metabolites. These data indicate that impairment of the glutathione salvage pathway, associated with enhanced oxidative stress, may have key therapeutic implications for this rare tumor type for which there are currently no specific targeted therapies.