Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of the most common forms of liver disease in Abstract The spectrum of nonalcoholic fatty liver disease (NAFLD) includes steatosis, nonalcoholic steatohepatitis (NASH), and cirrhosis. Recognition and timely diagnosis of these different stages, particularly NASH, is important for both potential reversibility and limitation of complications. Liver biopsy remains the clinical standard for defi nitive diagnosis. Diagnostic tools minimizing the need for invasive procedures or that add information to histologic data are important in novel management strategies for the growing epidemic of NAFLD. We describe an "omics" approach to detecting a reproducible signature of lipid metabolites, aqueous intracellular metabolites, SNPs, and mRNA transcripts in a double-blinded study of patients with different stages of NAFLD that involves profi ling liver biopsies, plasma, and urine samples. Using linear discriminant analysis, a panel of 20 plasma metabolites that includes glycerophospholipids, sphingolipids, sterols, and various aqueous small molecular weight components involved in cellular metabolic pathways, can be used to differentiate between NASH and steatosis. This identifi cation of differential biomolecular signatures has the potential to improve clinical diagnosis and facilitate therapeutic intervention of

Effective diagnosis of inflammation and cancer by molecular imaging is challenging because of interference from nonselective accumulation of the contrast agents in normal tissues. Here, we report a series of novel fluorescence imaging agents that efficiently target cyclooxygenase-2 (COX-2), which is normally absent from cells, but is found at high levels in inflammatory lesions and in many premalignant and malignant tumors. After either i.p. or i.v. injection, these reagents become highly enriched in inflamed or tumor tissue compared with normal tissue and this accumulation provides sufficient signal for in vivo fluorescence imaging. Further, we show that only the intact parent compound is found in the region of interest. COX-2-specific delivery was unambiguously confirmed using animals bearing targeted deletions of COX-2 and by blocking the COX-2 active site with high-affinity inhibitors in both in vitro and in vivo models. Because of their high specificity, contrast, and detectability, these fluorocoxibs are ideal candidates for detection of inflammatory lesions or early-stage COX-2-expressing human cancers, such as those in the esophagus, oropharynx, and colon.Cancer Res; 70(9); 3618-27. ©2010 AACR.

G protein-coupled receptor ligand-dependent transactivation of growth factor receptors has been implicated in human cancer cell proliferation, migration, and cell survival. For example, prostaglandin E 2 (PGE2)-induced transactivation of the EGF receptor (EGFR) in colorectal carcinoma cells is mediated by means of a c-Src-dependent mechanism and regulates cell proliferation and migration. Recent evidence indicates that ␤-arrestin 1 may act as an important mediator in G protein-coupled receptor-induced activation of c-Src. Whether ␤-arrestin 1 serves a functional role in these events is, however, unknown. We investigated the effects of PGE 2 on colorectal cancer cells expressing WT and mutant ␤-arrestin 1. Here we report that PGE 2 induces the association of a prostaglandin E receptor 4͞␤-arrestin 1͞c-Src signaling complex resulting in the transactivation of the EGFR and downstream Akt (PKB) signaling. The interaction of ␤-arrestin 1 and c-Src is critical for the regulation of colorectal carcinoma cell migration in vitro as well as metastatic spread of disease to the liver in vivo. These results show that the prostaglandin E͞␤-arrestin 1͞c-Src signaling complex is a crucial step in PGE2-mediated transactivation of the EGFR and may play a pivotal role in tumor metastasis. Furthermore, our data implicate a functional role for ␤-arrestin 1 as a mediator of cellular migration and metastasis. metastasis ͉ prostaglandin E2 ͉ c-Src ͉ EGF receptor ͉ prostaglandin E receptor G protein-coupled receptors (GPCRs) comprise the largest known family of plasma membrane receptors and consist of a seven-transmembrane-spanning region f lanked by an extracellular N terminus and an intracellular C terminus. Upon ligand binding, these receptors couple to heterotrimeric G proteins (G␣-and G␤␥-subunits) and catalyze the exchange of GDP for GTP, thus initiating a multitude of signaling events into the cell. These include the classical activation of phosholipases (phosholipases A, C, and D), protein kinases (PKA and PKC), and lipid kinases (phosphatidylinositol 3-kinase) as well as increased intracellular calcium levels. The desensitization of GPCRs occurs through a multistep process. GPCR kinases are recruited to the receptor by liberated ␤␥-subunits and phosphorylate the receptor on the cytoplasmic tail and intracellular loops. This phosphorylation event triggers the association of arrestin, which then traffics the receptors to clathrin-coated pits for endocytosis (1).Prostaglandins (PG) are important bioactive lipids which exert their effects through the activation of specific GPCRs as well as members of the peroxisome proliferator-activated receptor family. For example, PGE 2 is the ligand for four prostaglandin E (EP) receptor isoforms termed EP1, EP2, EP3, and EP4. Stimulation of these receptors elicits different intracellular responses (2). The stimulation of the EP1 receptor induces an increase in intracellular calcium by means of the activation of phospholipase C. EP2 and EP4 receptors couple to G␣s proteins, which generate incre...