Laboratory of Lipid Metabolism and Cancer

Santa Maria Imbaro, Italy

Laboratory of Lipid Metabolism and Cancer

Santa Maria Imbaro, Italy
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Degirolamo C.,IRCCS Instituto Oncologico Giovanni Paolo II | Degirolamo C.,Laboratory of Lipid Metabolism and Cancer | Modica S.,Laboratory of Lipid Metabolism and Cancer | Vacca M.,Laboratory of Lipid Metabolism and Cancer | And 8 more authors.
Hepatology | Year: 2015

Farnesoid X receptor (FXR) is the master regulator of bile acid (BA) homeostasis because it controls BA synthesis, influx, efflux, and detoxification in the gut/liver axis. Deregulation of BA homeostasis has been linked to hepatocellular carcinoma (HCC), and spontaneous hepatocarcinogenesis has been observed in FXR-null mice. This dreaded liver neoplasm has been associated with both FXR gene deletion and BA-mediated metabolic abnormalities after inactivation of FXR transcriptional activity. In the present study, we addressed the hypothesis that intestinal selective FXR reactivation would be sufficient to restore the fibroblast growth factor 15 (FGF15)/cholesterol-7alpha-hydroxylase (Cyp7a1) enterohepatic axis and eventually provide protection against HCC. To this end, we generated FXR-null mice with re-expression of constitutively active FXR in enterocytes (FXR-/-iVP16FXR) and corresponding control mice (FXR-/-iVP16). In FXR-null mice, intestinal selective FXR reactivation normalized BA enterohepatic circulation along with up-regulation of intestinal FXR transcriptome and reduction of hepatic BA synthesis. At 16 months of age, intestinal FXR reactivation protected FXR-null mice from spontaneous HCC development that occurred in otherwise FXR-null mice. Activation of intestinal FXR conferred hepatoprotection by restoring hepatic homeostasis, limiting cellular proliferation through reduced cyclinD1 expression, decreasing hepatic inflammation and fibrosis (decreased signal transducer and activator of transcription 3 activation and curtailed collagen deposition). Conclusion: Intestinal FXR is sufficient to restore BA homeostasis through the FGF15 axis and prevent progression of liver damage to HCC even in the absence of hepatic FXR. Intestinal-selective FXR modulators could stand as potential therapeutic intervention to prevent this devastating hepatic malignancy, even if carrying a somatic FXR mutation. © 2014 by the American Association for the Study of Liver Diseases.

Lo Sasso G.,Laboratory of Lipid Metabolism and Cancer | Bovenga F.,Laboratory of Lipid Metabolism and Cancer | Murzilli S.,Laboratory of Lipid Metabolism and Cancer | Salvatore L.,Laboratory of Lipid Metabolism and Cancer | And 10 more authors.
Gastroenterology | Year: 2013

Background & Aims: Liver X receptors (LXRs) are transcriptional regulators of cholesterol metabolism, controlling cholesterol flow into cells, catabolism, and efflux. Cholesterol controls cell proliferation; disruptions in cholesterol metabolism have been associated with the development of colon cancer. We investigated whether expression of activated LXR protects against intestinal tumorigenesis in mice. Methods: We analyzed the development of colon cancer in mice that express a constitutive active form of LXRα only in the intestinal epithelium, under the control of villin promoter (iVP16LXRα). These mice were crossed with adenomatous polyposis coli (Apc)min/+ mice, or given azoxymethane followed by dextran sodium sulfate, to assess intestinal tumor formation. We also assessed proliferation and apoptosis of a human colorectal cancer cell line (HT29) transfected with an adenoviral vector that expressed Ad VP16hLXRα, compared with cells expressing AdVP16 (control), and their ability to form xenograft tumors in mice. HT29 cells also were incubated with the LXR ligand GW3965. Results: In human colorectal cancer cells, ligand-induced activation of LXR or transfection with Ad VP16hLXRα blocked the G1 phase, increased caspase-dependent apoptosis, and slowed growth of xenograft tumors in mice. iVP16LXRα mice formed fewer, smaller tumors than VP16 (control) mice after administration of azoxymethane and dextran sodium sulfate. APCmin/+/iVP16LXRα mice also developed fewer, smaller intestinal tumors than APCmin/+/iVP16 mice. Gene expression analysis indicated that activation of LXRα affected lipid metabolic networks and increased cholesterol efflux in the intestine. Conclusions: Expression of activated LXRα blocks proliferation of human colorectal cancer cells and slows the growth of xenograft tumors in mice. It also reduces intestinal tumor formation after administration of chemical carcinogens, and in Apc min/+ mice. LXR agonists therefore might be developed as therapeutic treatments for colorectal cancer. © 2013 AGA Institute.

Bonamassa B.,Laboratory of Lipid Metabolism and Cancer | Moschetta A.,Laboratory of Lipid Metabolism and Cancer | Moschetta A.,University of Bari | Moschetta A.,Italian National Cancer Institute | Moschetta A.,National Institute for Digestive Diseases
Trends in Endocrinology and Metabolism | Year: 2013

Modulation of the cholesterol-sensing liver X receptors (LXRs) and their downstream targets has emerged as promising therapeutic avenues in atherosclerosis. The intestine is important for its unique capabilities to act as a gatekeeper for cholesterol absorption and to participate in the process of cholesterol elimination in the feces and reverse cholesterol transport (RCT). Pharmacological and genetic intestine-specific LXR activation have been shown to protect against atherosclerosis. In this review we discuss the LXR-targeted molecular players in the enterocytes as well as the intestine-driven pathways contributing to cholesterol homeostasis with therapeutic potential as targets in the prevention and treatment of atherosclerosis. © 2012 Elsevier Ltd.

Bellafante E.,Laboratory of Lipid Metabolism and Cancer | Murzilli S.,Laboratory of Lipid Metabolism and Cancer | Salvatore L.,Laboratory of Lipid Metabolism and Cancer | Latorre D.,University of Bari | And 5 more authors.
Hepatology | Year: 2013

Development of hepatic steatosis and its progression to steatohepatitis may be the consequence of dysfunction of several metabolic pathways, such as triglyceride synthesis, very low-density lipoprotein (VLDL) secretion, and fatty acid β-oxidation. Peroxisome proliferator-activated receptor γ coactivator-1β (PGC-1β) is a master regulator of mitochondrial biogenesis and oxidative metabolism, lipogenesis, and triglyceride (TG) secretion. Here we generated a novel mouse model with constitutive hepatic activation of PGC-1β and studied the role of this transcriptional coactivator in dietary-induced steatosis and steatohepatitis. Selective activation of PGC-1β within hepatocytes is able to protect the liver from lipid overload and from progression to fibrosis. The protective function exerted by PGC-1β is due to its ability to induce mitochondrial oxidative phosphorylation, fatty acid β-oxidation, and citrate cycle, as well as to decrease oxidative stress and promote TG secretion in the blood stream. These findings bolster the concept that a combined hepatic specific action of PGC-1β on lipid synthesis and secretion, as well as on mitochondrial biogenesis and function, could protect against steatohepatitis. © 2013 American Association for the Study of Liver Diseases.

Cicione C.,Laboratory of Lipid Metabolism and Cancer | Degirolamo C.,Laboratory of Lipid Metabolism and Cancer | Moschetta A.,Laboratory of Lipid Metabolism and Cancer | Moschetta A.,University of Bari | Moschetta A.,Italian National Cancer Institute
Hepatology | Year: 2012

Fibroblast growth factors (FGFs) 15/19 and 21 belong to the FGF endocrine subfamily. They present the intriguing characteristic to be transcribed and secreted in certain tissues and to act as hormones. The insulin-mimetic properties of FGF21 and the regulatory role of FGF15/19 in bile acid and glucose homeostasis endorse these hormones as druggable targets in metabolic disorders. Here, we present details on discoveries, identification, transcriptional regulation, and mechanism of actions of FGF15/19 and FGF21 with a critical perspective view on their putative role as metabolic integrators in the liver. © 2012 American Association for the Study of Liver Diseases.

Modica S.,Laboratory of Lipid Metabolism and Cancer | Petruzzelli M.,Laboratory of Lipid Metabolism and Cancer | Petruzzelli M.,University of Bari | Bellafante E.,Laboratory of Lipid Metabolism and Cancer | And 12 more authors.
Gastroenterology | Year: 2012

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. © 2012 AGA Institute.

Sasso G.L.,Laboratory of Lipid Metabolism and Cancer | Murzilli S.,Laboratory of Lipid Metabolism and Cancer | Salvatore L.,Laboratory of Lipid Metabolism and Cancer | D'Errico I.,Laboratory of Lipid Metabolism and Cancer | And 9 more authors.
Cell Metabolism | Year: 2010

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 hepaticspecific 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. © 2010 Elsevier Inc.

Moschetta A.,Laboratory of Lipid Metabolism and Cancer | Moschetta A.,University of Bari
Cancer Discovery | Year: 2011

Both primary and transformed cells need cholesterol for their growth. Guo and colleagues unraveled the connection between epidermal growth factor receptor mutations in glioblastoma and increased cholesterol influx via sterol regulatory element-binding protein 1 and low-density lipoprotein receptor (LDLR) increase. They propose the activation of the liver X receptor-inducible degrader of LDLR-LDLR axis as a therapeutic approach to reduce intracellular cholesterol, block tumor growth, and induce cell death. © 2011 American Association for Cancer Research.

Gadaleta R.M.,University Utrecht | Gadaleta R.M.,Laboratory of Lipid Metabolism and Cancer | van Mil S.W.C.,University Utrecht | Oldenburg B.,University Utrecht | And 3 more authors.
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2010

The nuclear receptor Farnesoid X Receptor (FXR) critically regulates nascent bile formation and bile acid enterohepatic circulation. Bile acids and FXR play a pivotal role in regulating hepatic inflammation and regeneration as well as in regulating extent of inflammatory responses, barrier function and prevention of bacterial translocation in the intestinal tract. Recent evidence suggests, that the bile acid-FXR interaction is involved in the pathophysiology of a wide range of diseases of the liver, biliary and gastrointestinal tract, such as cholestatic and inflammatory liver diseases and hepatocellular carcinoma, inflammatory bowel disease and inflammation-associated cancer of the colon and esophagus. In this review we discuss current knowledge of the role the bile acid-FXR interaction has in (patho)physiology of the liver, biliary and gastrointestinal tract, and proposed underlying mechanisms, based on in vitro data and experimental animal models. Given the availability of highly potent synthetic FXR agonists, we focus particularly on potential relevance for human disease. © 2010 Elsevier B.V. All rights reserved.

Modica S.,Laboratory of Lipid Metabolism and Cancer
Nuclear receptor signaling | Year: 2010

Originally called retinoid X receptor interacting protein 14 (RIP14), the farnesoid X receptor (FXR) was renamed after the ability of its rat form to bind supra-physiological concentrations of farnesol. In 1999 FXR was de-orphanized since primary bile acids were identified as natural ligands. Strongly expressed in the liver and intestine, FXR has been shown to be the master transcriptional regulator of several entero-hepatic metabolic pathways with relevance to the pathophysiology of conditions such as cholestasis, fatty liver disease, cholesterol gallstone disease, intestinal inflammation and tumors. Furthermore, given the importance of FXR in the gut-liver axis feedbacks regulating lipid and glucose homeostasis, FXR modulation appears to have great input in diseases such as metabolic syndrome and diabetes. Exciting results from several cellular and animal models have provided the impetus to develop synthetic FXR ligands as novel pharmacological agents. Fourteen years from its discovery, FXR has gone from bench to bedside; a novel nuclear receptor ligand is going into clinical use.

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