Tumorigenesis involves metabolic reprogramming and abnormal lipid metabolism, which is manifested by increased endogenous fat mobilization, hypertriglyceridemia, and increased fatty acid synthesis. Fatty acid synthase (FASN) is a key enzyme for the de novo synthesis of fatty acids, and monoacylglycerol esterase (MGLL) is an important metabolic enzyme that converts triglycerides into free fatty acids. Both enzymes play an important role in lipid metabolism and are associated with tumor-related signaling pathways, the most common of which is the PI3K-AKT signaling pathway. They can also regulate the immune microenvironment, participate in epithelial-mesenchymal transition, and then regulate tumor invasion and metastasis. Current literature have shown that these two genes are abnormally expressed in many types of tumors and are highly correlated with tumor migration and invasion. This article introduces the structures and functions of FASN and MGLL, their relationship with abnormal lipid metabolism, and the mechanism of the regulation of tumor invasion and metastasis and reviews the research progress of the relationship of FASN and MGLL with tumor invasion and metastasis.
Cell Line, Tumor ; Fatty Acid Synthase, Type I/metabolism* ; Humans ; Lipid Metabolism ; Monoacylglycerol Lipases/metabolism* ; Neoplasms ; Phosphatidylinositol 3-Kinases ; Signal Transduction ; Tumor Microenvironment

The aim of this study was to explore the effect of emodin on lipid accumulation and inflammation in hepatocytes. The cell morphology was observed by microscopy. LDH release was detected by the kit. Levels of intracellular lipid droplets were observed by oil red O staining. The contents of TC and TG in cells were detected by the kit. Western blot was used to determine protein expressions of FASN,SREBF2,APOB,IL-6 and p-NF-κB in hepatocytes. The results showed that the levels of L02 cell LDH were significantly increased after being treated with emodin,and the cells showed shrinkage,volume reduction,decrease in quantity with the increase of dose. Red lipid droplets were observed in L02 hepatocytes. Intracellular TC and TG contents of L02 cell increased in a concentrationdependent manner,with significant differences between medium and high-dose groups( P < 0. 05). Protein expressions of FASN,SREBF2,IL-6 and p-NF-κB were significantly higher than those of the control group,and the expression level of APOB was significantly lower than that of the control group( P<0. 05). In conclusion,emodin could induce lipid accumulation and inflammatory damage in hepatocytes in a dose-dependent manner,which in turn could damage liver cells. This process was related to the up-regulation of FASN,SREBF2,IL-6,p-NF-κB,as well as the down-regulation of the protein expression of APOB.
Apolipoprotein B-100 ; metabolism ; Cells, Cultured ; Emodin ; pharmacology ; Fatty Acid Synthase, Type I ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Humans ; Inflammation ; Interleukin-6 ; metabolism ; Lipid Metabolism ; Lipids ; NF-kappa B ; metabolism ; Sterol Regulatory Element Binding Protein 2 ; metabolism

OBJECTIVETo investigate the effect of Hepatitis B Virus X Protein (HBx) on the expression of lipid metabolism-related genes and its role in pathogenesis of hepatocyte fatty degeneration.

METHODSHepatitis B Virus X gene eukaryon expression vector pIRES2-eGFP-HBx was transfected into HepG2 cells to establish HepG2/HBx cell model for HBx expression. HepG2 cells transfected with pIRES2-eGFP (HepG2/pIRES2 cell) and non-transfected were used as controls. At 24, 48 and 72 hours after transfection, the expression of green fluorescent protein (GFP) was observed by fluorescence microscope and the triglyceride(TG) content was detected. RT-PCR and Western blot were applied to detect the levels of sterol regulatory element binding protein-1 (SREBP-1), liver x receptor alpha (LXRalpha) mRNA and the levels of HBx, LXRalpha and fatty acid synthase (FAS) protein. At 24, 48 and 72 hours after transfection, the expression of GFP was found in HepG2/HBx and HepG2/pIRES2 cells, and increased gradually. The expression of HBx was detected only in HepG2/HBx cells, and was increased with time after transfection (F = 32.21, P less than 0.01). These suggested successful obtaining of HepG2-HBx cell model for HBx expression.

RESULTSAt 24h, 48h and 72h after transfection, the expression levels of LXRalpha mRNA (0.386+/-0.055, 0.505+/-0.071, 0.649+/-0.058 ) and SREBP-1 mRNA (0.395+/-0.055, 0.548+/-0.047, 0.795+/-0.058), as well as the levels of LXRalpha protein(0.178+/-0.036, 0.263+/-0.047, 0.347+/-0.058) and FAS protein(0.436+/-0.055, 0.608+/-0.053, 0.827+/-0.046) in HepG2-HBx group were dramatically higher than those in the controls at the same time points (all P less than 0.05/0.01), and were gradually increased with time (all P less than 0.05/0.01). A positive correlationship was observed between HBX protein level and the LXRalpha, SREbP-1 mRNA and LXRalpha, FAS protein levels. The difference of TG content between HepG2/HBx group and control groups was not statistically significant (P more than 0.05).

CONCLUSIONSHBx-LXRalpha-SREBP-1/FAS pathway suggested regulating transcription and expression of lipid metabolism-related genes, which might be one of the important molecular mechanism causing hepatocyte fatty degeneration.

Carcinoma, Hepatocellular ; metabolism ; Fatty Acid Synthase, Type I ; metabolism ; Hep G2 Cells ; Humans ; Lipid Metabolism ; genetics ; Liver Neoplasms ; metabolism ; Liver X Receptors ; Orphan Nuclear Receptors ; metabolism ; Sterol Regulatory Element Binding Protein 1 ; metabolism ; Trans-Activators ; genetics ; Transfection

OBJECTIVETo determine fatty acid synthase (FAS) expression in human multiple myeloma and verify its potential as a therapeutic target in multiple myeloma.

METHODSFAS expression was determined by immunohistochemistry, reverse-transcription polymerase chain reaction (RT-PCR) and immunoblot analysis in bone marrow samples obtained from 27 patients with multiple myeloma (MM patients) and peripheral blood mononuclear cells (PBMCs) obtained from 12 healthy donors. In parallel, additional analyses were performed on 2 human multiple myeloma cell lines, U266 and RPMI8226. U266 cells were treated with cerulenin at various concentrations (5 to 320 microg/ml) for 24 h, and metabolic activity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Apoptosis was evaluated by dual Annexin V/PI (propidium iodide) labeling and flow cytometry (FCM) in U266 cells treated with 20 (g/ml cerulenin for 12 h or 24 h.

RESULTSBy immunohistochemistry, we found that 19 of 27 bone marrow samples obtained from MM patients expressed significantly high levels of FAS. Similarly, by RT-PCR, 22 of 27 bone marrow samples obtained from MM patients, U266 and RPMI8226 showed FAS expression, whereas PBMC samples from 12 healthy donors did not express detectable level of FAS. FAS protein expression was confirmed by immunoblot analysis in 16 of 27 bone marrow samples obtained from MM patients, U266 and RPMI8226 cell lines, and no FAS protein expression was detected in PBMC samples from 12 healthy donors. U266 cells were highly sensitive to cerulenin treatment, with a dosage-related effect on metabolic activity, as a measure for cell proliferation. U266 cells treated with 20 microg/ml cerulenin for 12 and 24 h also showed early sign of apoptosis with 56.9% and 69.3% Annexin V(+)/PI(-) cells, and late apoptotic and necrotic cells with 3.2% and 17.6% Annexin V(+)/PI(+) cells.

CONCLUSIONIncreased FAS expression existed in multiple myeloma samples and human myeloma cell lines. Cerulenin greatly inhibited metabolic activity/cell proliferation of U266 cells and induced apoptosis, suggesting that FAS is an effective target for pharmacological therapy in human multiple myeloma.

Adult ; Aged ; Apoptosis ; drug effects ; Base Sequence ; Blotting, Western ; Case-Control Studies ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cerulenin ; pharmacology ; DNA Primers ; genetics ; Enzyme Inhibitors ; pharmacology ; Fatty Acid Synthase, Type I ; antagonists & inhibitors ; genetics ; metabolism ; Fatty Acid Synthesis Inhibitors ; pharmacology ; Female ; Humans ; Immunohistochemistry ; Male ; Middle Aged ; Multiple Myeloma ; drug therapy ; enzymology ; genetics ; pathology ; RNA, Messenger ; genetics ; metabolism ; RNA, Neoplasm ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction