Early Neutrophilia Marked by Aerobic Glycolysis Sustains Host Metabolism and Delays Cancer Cachexia.

An elevated neutrophil-lymphocyte ratio negatively predicts the outcome of patients with cancer and is associated with cachexia, the terminal wasting syndrome. Here, using murine model systems of colorectal and pancreatic cancer we show that neutrophilia in the circulation and multiple organs, accompanied by extramedullary hematopoiesis, is an early event during cancer progression. Transcriptomic and metabolic assessment reveals that neutrophils in tumor-bearing animals utilize aerobic glycolysis, similar to cancer cells. Although pharmacological inhibition of aerobic glycolysis slows down tumor growth in C26 tumor-bearing mice, it precipitates cachexia, thereby shortening the overall survival. This negative effect may be explained by our observation that acute depletion of neutrophils in pre-cachectic mice impairs systemic glucose homeostasis secondary to altered hepatic lipid processing. Thus, changes in neutrophil number, distribution, and metabolism play an adaptive role in host metabolic homeostasis during cancer progression. Our findings provide insight into early events during cancer progression to cachexia, with implications for therapy.

Cancer Treatment in the Genomic Era.

The complexity of human cancer underlies its devastating clinical consequences. Drugs designed to target the genetic alterations that drive cancer have improved the outcome for many patients, but not the majority of them. Here, we review the genomic landscape of cancer, how genomic data can provide much more than a sum of its parts, and the approaches developed to identify and validate genomic alterations with potential therapeutic value. We highlight notable successes and pitfalls in predicting the value of potential therapeutic targets and discuss the use of multi-omic data to better understand cancer dependencies and drug sensitivity. We discuss how integrated approaches to collecting, curating, and sharing these large data sets might improve the identification and prioritization of cancer vulnerabilities as well as patient stratification within clinical trials. Finally, we outline how future approaches might improve the efficiency and speed of translating genomic data into clinically effective therapies and how the use of unbiased genome-wide information can identify novel predictive biomarkers that can be either simple or complex.

Biliary Phospholipids Sustain Enterocyte Proliferation and Intestinal Tumor Progression via Nuclear Receptor Lrh1 in mice.

The proliferative-crypt compartment of the intestinal epithelium is enriched in phospholipids and accumulation of phospholipids has been described in colorectal tumors. Here we hypothesize that biliary phospholipid flow could directly contribute to the proliferative power of normal and dysplastic enterocytes. We used Abcb4-/- mice which lack biliary phospholipid secretion. We first show that Abcb4-/- mice are protected against intestinal tumorigenesis. At the molecular level, the transcriptional activity of the nuclear receptor Liver Receptor Homolog-1 (Lrh1) is reduced in Abcb4-/- mice and its re-activation re-establishes a tumor burden comparable to control mice. Feeding Abcb4-/- mice a diet supplemented with phospholipids completely overcomes the intestinal tumor protective phenotype, thus corroborating the hypothesis that the absence of biliary phospholipids and not lack of Abcb4 gene per se is responsible for the protection. In turn, phospholipids cannot re-establish intestinal tumorigenesis in Abcb4-/- mice crossed with mice with intestinal specific ablation of Lrh1, a nuclear hormone receptor that is activates by phospholipids. Our data identify the key role of biliary phospholipids in sustaining intestinal mucosa proliferation and tumor progression through the activation of nuclear receptor Lrh1.

Mechanisms of metabolic dysfunction in cancer-associated cachexia.

Metabolic dysfunction contributes to the clinical deterioration observed in advanced cancer patients and is characterized by weight loss, skeletal muscle wasting, and atrophy of the adipose tissue. This systemic syndrome, termed cancer-associated cachexia (CAC), is a major cause of morbidity and mortality. While once attributed solely to decreased food intake, the present description of cancer cachexia is a disorder of multiorgan energy imbalance. Here we review the molecules and pathways responsible for metabolic dysfunction in CAC and the ideas that led to the current understanding.

A switch from white to brown fat increases energy expenditure in cancer-associated cachexia.

Cancer-associated cachexia (CAC) is a wasting syndrome characterized by systemic inflammation, body weight loss, atrophy of white adipose tissue (WAT) and skeletal muscle. Limited therapeutic options are available and the underlying mechanisms are poorly defined. Here we show that a phenotypic switch from WAT to brown fat, a phenomenon termed WAT browning, takes place in the initial stages of CAC, before skeletal muscle atrophy. WAT browning is associated with increased expression of uncoupling protein 1 (UCP1), which uncouples mitochondrial respiration toward thermogenesis instead of ATP synthesis, leading to increased lipid mobilization and energy expenditure in cachectic mice. Chronic inflammation and the cytokine interleukin-6 increase UCP1 expression in WAT, and treatments that reduce inflammation or ß-adrenergic blockade reduce WAT browning and ameliorate the severity of cachexia. Importantly, UCP1 staining is observed in WAT from CAC patients. Thus, inhibition of WAT browning represents a promising approach to ameliorate cachexia in cancer patients.

Selective activation of nuclear bile acid receptor FXR in the intestine protects mice against cholestasis.

BACKGROUND & AIMS: Cholestasis is a liver disorder characterized by impaired bile flow, reduction of bile acids (BAs) in the intestine, and retention of BAs in the liver. The farnesoid X receptor (FXR) is the transcriptional regulator of BA homeostasis. Activation of FXR by BAs reduces circulating BA levels in a feedback mechanism, repressing hepatic cholesterol 7α-hydroxylase (Cyp7a1), the rate-limiting enzyme for the conversion of cholesterol to BAs. This mechanism involves the hepatic nuclear receptor small heterodimer partner and the intestinal fibroblast growth factor (FGF) 19 and 15. We investigated the role of activation of intestine-specific FXR in reducing hepatic levels of BAs and protecting the liver from cholestasis in mice. METHODS: We generated transgenic mice that express a constitutively active FXR in the intestine. Using FXR gain- and loss-of-function models, we studied the roles of intestinal FXR in mice with intrahepatic and extrahepatic cholestasis. RESULTS: Selective activation of intestinal FXR induced FGF15 and repressed hepatic Cyp7a1, reducing the pool size of BAs and changing the BA pool composition. Activation of intestinal FXR protected mice from obstructive extrahepatic cholestasis after bile duct ligation or administration of α-naphthylisothiocyanate. In Mdr2(-/-) mice, transgenic expression of activated FXR in the intestine protected against liver damage, whereas absence of FXR promoted progression of liver disease. CONCLUSIONS: Activation of FXR transcription in the intestine protects the liver from cholestasis in mice by inducing FGF15 expression and reducing the hepatic pool of BA; this approach might be developed to reverse cholestasis in patients.

Discovery of gemfibrozil analogues that activate PPARα and enhance the expression of gene CPT1A involved in fatty acids catabolism.

A new series of gemfibrozil analogues conjugated with α-asarone, trans-stilbene, chalcone, and their bioisosteric modifications were synthesized and evaluated to develop PPARα agonists. In this attempt, we have removed the methyls on the phenyl ring of gemfibrozil and introduced the above scaffolds in para position synthesizing two series of derivatives, keeping the dimethylpentanoic skeleton of gemfibrozil unaltered or demethylated. Four compounds exhibited good activation of the PPARα receptor and were also screened for their activity on PPARα-regulated gene CPT1A.

Intestinal specific LXR activation stimulates reverse cholesterol transport and protects from atherosclerosis.

Several steps of the HDL-mediated reverse cholesterol transport (RCT) are transcriptionally regulated by the nuclear receptors LXRs in the macrophages, liver, and intestine. Systemic LXR activation via synthetic ligands induces RCT but also causes increased hepatic fatty acid synthesis and steatosis, limiting the potential therapeutic use of LXR agonists. During the last few years, the participation of the intestine in the control of RCT has appeared more evident. Here we show that while hepatic-specific LXR activation does not contribute to RCT, intestinal-specific LXR activation leads to decreased intestinal cholesterol absorption, improved lipoprotein profile, and increased RCT in vivo in the absence of hepatic steatosis. These events protect against atherosclerosis in the background of the LDLR-deficient mice. Our study fully characterizes the molecular and metabolic scenario that elects the intestine as a key player in the LXR-driven protective environment against cardiovascular disease.

Intestinal ecology in the metabolic syndrome.

Nutritional and genetic factors alter the intestinal microflora, predisposing individuals toward metabolic syndrome. Gewirtz and coworkers (Vijay-Kumar et al., 2010), employing Toll-like receptor 5 null mice, present evidence for a direct relationship between malfunction of the innate immune system, changes in gut microbiota composition, and development of metabolic syndrome.

Synthesis and biological evaluation of 2-heteroarylthioalkanoic acid analogues of clofibric acid as peroxisome proliferator-activated receptor alpha agonists.

A series of 2-heteroarylthioalkanoic acids were synthesized through systematic structural modifications of clofibric acid and evaluated for human peroxisome proliferator-activated receptor alpha (PPARalpha) transactivation activity, with the aim of obtaining new hypolipidemic compounds. Some thiophene and benzothiazole derivatives showing a good activation of the receptor alpha were screened for activity against the PPARgamma isoform. The gene induction of selected compounds was also investigated in the human hepatoma cell line.

Micellar lipid composition profoundly affects LXR-dependent cholesterol transport across CaCo2 cells.

Intraluminal phospholipids affect micellar solubilization and absorption of cholesterol. We here study cholesterol transport from taurocholate-phospholipid-cholesterol micelles to CaCo2 cells, and associated effects on ABC-A1 mediated cholesterol efflux. Micellar incorporation of egg-yolk-phosphatidylcholine markedly increased apical retention of the sterol with decreased expression of ABC-A1, an effect that is prevented by synthetic liver X receptor (LXR) or retinoid X receptor (RXR) agonists. On the other hand, incorporation of lyso-phosphatidylcholine (LysoPC) increased ABC-A1-HDL-dependent basolateral cholesterol efflux, an effect that is abated when LXR is silenced. Thus, the modulation of cholesterol metabolism via intraluminal phospholipids is related to the activity of the oxysterol nuclear receptor LXR.

Taurodeoxycholate-induced intestinal injury is modulated by oxidative stress-dependent pre-conditioning like mechanisms.

Mechanisms by which hydrophobic bile salts cause tissue changes below their critical micellar concentration (CMC, 1-2mM) and above (4-8mM) remain poorly understood. In this study, rat colonic mucosa was exposed to different concentrations of taurodeoxycholate (TDC), t-butyl-hydroperoxide (t-BH) or glutathione ester with or without pre-incubation with 2mM TDC. Exposure to 2mM TDC was associated with 10% higher tissue levels of total glutathione (GSH, basal values: 33.7+/-3.3 nmol/mg prot). With TDC 8mM, GSH decreased to 16.4+/-2.3 nmol/mg prot (P<0.05), oxidized glutathione (GSSG) increased by 60% (P<0.05), glutathione peroxidase (GSH-Px) and reductase activities were threefold increased, protein carbonyls fourfold increased, protein sulfhydrils decreased by 78%, lactate dehydrogenase (LDH) and GSSG release in the incubation medium were sixfold higher. In 2mM TDC pre-treated tissues, the subsequent incubation with 8mM TDC induced a lower loss of tissue GSH, and a lower release of LDH and GSSG. Pre-incubation with 2mM TDC partly protected against t-BH toxicity, while glutathione ester protected against 8mM TDC toxicity. In conclusion, TDC exposure causes opposite effects depending on CMC: induction of antioxidant protective systems including glutathione system (pre-conditioning effect) was observed with TDC below CMC, oxidative damages pointing to decreased mucosal detoxification potential with above CMC.

Abcg5/8 independent biliary cholesterol excretion in Atp8b1-deficient mice.

BACKGROUNDS & AIMS: ATP8B1 is a phosphatidylserine flippase in the canalicular membrane; patients with mutations in ATP8B1 develop severe chronic (PFIC1) or periodic (BRIC1) cholestatic liver disease. We have observed that Atp8b1 deficiency leads to enhanced biliary cholesterol excretion. It has been established that biliary cholesterol excretion depends on transport by the heterodimer Abcg5/Abcg8. We hypothesized that the increased cholesterol output was due to enhanced extraction from the altered canalicular membrane rather than to higher Abcg5/Abcg8 activity. We therefore studied the relation between Abcg5/Abcg8 expression and biliary cholesterol excretion in mice lacking Atp8b1, Abcg8, or both (GF mice). METHODS: Bile formation was studied in LXR agonist-fed wild-type mice as well as mice lacking Atp8b1 or Abcg8, or in GF mice upon infusion of taurocholate. Bile samples were analyzed for cholesterol, bile salt, phospholipids, and ectoenzyme content. RESULTS: LXR agonist increased Abcg5/8 expression, and this was accompanied by increased biliary cholesterol output in both wild-type and Atp8b1(G308V/G308V) mice. However, Atp8b1(G308V/G308V) mice maintained higher cholesterol output. Although in Abcg8(-/-) mice biliary cholesterol output was severely reduced, GF mice displayed high biliary cholesterol output, which was comparable with wild-type mice. Bile of both Atp8b1(G308V/G308V) and GF mice displayed elevated levels of phosphatidylserine and sphingomyelin, indicating membrane stress. CONCLUSIONS: Our data demonstrate that the increased biliary cholesterol excretion in Atp8b1-deficient mice is independent of Abcg5/8 activity. This implicates that Atp8b1 deficiency leads to a decrease in the detergent resistance and subsequent nonspecific extraction of cholesterol from the canalicular membrane by bile salts.

A translational view on the biliary lipid secretory network.

Bile formation springs from an extraordinary sophisticated secretory network, which combines the activity of transport proteins with the physico-chemical properties of small albeit powerful lipophilic compounds. This robust interplay is activated in response to dietary stimuli, circadian rhythms, and metabolic demands to regulate cholesterol disposal, lipid digestion and absorption in the enterohepatic system. As a result, bile flow is a complex multi-organ effort that requires an integrated flux of information between liver and intestine. A coordinate regulatory task is achieved by nuclear receptors, which are ligand activated transcription factors, responsible for the coherent activation of sets of genes involved in multiple physiological actions, including hepato-biliary homeostasis. Mastering the molecular pathways underlying functional and pharmacological modulation of bile flow has great translational value for potential future treatment of cholestasis and cholelithiasis. In this review, we focus on recent discoveries in the functional biology of bile formation with the explicit aim of underlining their putative clinical relevance.

Targeting the liver in the metabolic syndrome: evidence from animal models.

The metabolic syndrome is an emerging global epidemic characterized by clustering of metabolic abnormalities leading to increased cardiovascular risk: glucose intolerance or type 2 diabetes, dyslipidemia, hypertension, and "central" obesity. Scientists are decoding and piecing together the molecular texture underlying the metabolic syndrome: insulin resistance and dyslipidemia stand out as central pathophysiological events. In this picture, the liver rises as the leading organ in the maintenance of metabolic fitness; it serves as the first relay station for processing dietary information, and encloses the whole biochemical machinery for both glucose and lipid storage and disposal. In addition, the liver is a target of the different endocrine molecules secreted by pancreatic beta-cells and adipose tissue. Evidence collected in animal models supports the central role of the liver in the metabolic syndrome. While specific bereft of insulin sensitivity in skeletal muscle and adipose tissue fails to induce diabetes at certain extent, this is constantly the outcome in case of hepatic insulin resistance. Also, dyslipidemia is currently interpreted as the result of increased flux of free fatty acids to the liver with ensuing misbalance of lipoprotein synthesis and removal. In this review we bring together recent advances in the field of lipid sensing nuclear receptors, adipokines and other molecules responsible for metabolic fitness, and provide a putative coherent frame to conceive the pathophysiology of the metabolic syndrome.

Intestinal mucosal damage caused by non-steroidal anti-inflammatory drugs: role of bile salts.

The strong analgesic, anti-inflammatory effects of non-steroidal anti-inflammatory drugs (NSAIDs) are hampered by high occurrence of gastrointestinal side effects. Therapeutic actions of NSAIDs result from cyclooxygenase (COX) enzymes inhibition with reduced synthesis of prostaglandins, major modulators of inflammation. Since prostaglandins also regulate key events in gut homeostasis -mucosal secretion, blood flow, epithelial regeneration - COX inhibition has been accepted as the reason for NSAID gastrointestinal toxicity. Several findings challenge this theory: first, intestinal damage by NSAIDs occurs also in COX-1 knockout mice, demonstrating that topical (non-prostaglandin mediated) mechanisms are involved; second, no correlation is found in vivo between the extent of intestinal injury and the degree of inhibition of prostaglandin synthesis; third, bile flow interruption in animal models completely prevents intestinal damage by parenterally administered NSAIDs. What is in bile that could play a role in NSAID toxicity? This timely review will critically discuss the role of bile salts in NSAID-dependent gut damage.