Expression of liver-type fatty-acid-binding protein, fatty acid synthase and vascular endothelial growth factor in human lung carcinoma

FABP1 expression in human tumors: a tissue microarray study on 17,071 tumors

Fatty acid-binding proteins (FABPs) play a pivotal role in the metabolism of fatty acids and are expressed in a tissue-specific manner. FABP1 is most abundantly expressed in the liver where it accounts for about 10% of the total cytosolic protein and is thought to have diagnostic utility. To comprehensively determine FABP1 expression in normal and neoplastic tissues, a tissue microarray containing 17,071 samples from 150 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. Among normal tissues, a strong FABP1 immunostaining was observed in hepatocytes, proximal tubuli of the kidney and epithelium of small intestine, appendix, and the colorectum. FABP1 positivity was found in 24 of 150 tumor categories, including 17 tumor categories with at least 1 strongly positive case. The highest FABP1 positivity rates were seen in colorectal adenomas (86%), in colorectal adenocarcinomas (71.1%), and in hepatocellular carcinomas (65.3%), followed by mucinous carcinoma of the ovary (34.6%), cholangiocarcinoma (21.6%), and various adenocarcinomas from the digestive tract (10-23%). Eleven additional entities had positivity rates between 0.2 and 6.5%. FABP1 staining was not seen in 169 primary adenocarcinomas of the lung. In colorectal cancer, reduced FABP1 expression was linked to poor-grade, right-sided tumor location, microsatellite instability (p < 0.0001 each), and absence of BRAF V600E mutations (p = 0.001), but unrelated to pT and pN status. FABP1 expression has considerably high tumor specificity. As FABP1 expression was virtually absent in adenocarcinomas of the lung, FABP1 immunohistochemistry might be particularly helpful to assist in the identification of metastatic colorectal or gastrointestinal adenocarcinoma to the lung.

Effects of Apoptin-Induced Endoplasmic Reticulum Stress on Lipid Metabolism, Migration, and Invasion of HepG-2 Cells

In this study, we investigated the effects of Apoptin-induced endoplasmic reticulum (ER) stress on lipid metabolism, migration and invasion of HepG-2 cells, and preliminarily explored the relationship between endoplasmic reticulum stress, lipid metabolism, migration, and invasion. The effects of Apoptin on ER function and structure in HepG-2 cells were determined by flow cytometry, fluorescence staining and western blotting by assessing the expression levels of ER stress related proteins. The effects of Apoptin on HepG-2 cells' lipid metabolism were determined by western blot analysis of the expression levels of triglyceride, cholesterol, and lipid metabolism related enzymes. The effects of Apoptin on HepG-2 cells' migration and invasion were studied using migration and invasion assays and by Western-blot analysis of the expression of proteins involved in migration and invasion. The in vivo effects of endoplasmic reticulum stress on lipid metabolism, migration and invasion of HepG-2 cells were also investigated by immunohistochemistry analysis of tumor tissues from HepG2 cells xenografted nude mice models. Both in vitro and in vivo experiments showed that Apoptin can cause a strong and lasting ER stress response, damage ER functional structure, significantly change the expression levels of lipid metabolism related enzymes and reduce the migration and invasion abilities of HepG-2 cells. Apoptin can also affect HepG-2 cells' lipid metabolism through endoplasmic reticulum stress and the abnormal expression of enzymes closely related to tumor migration and invasion. These results also showed that lipid metabolism may be one of the main inducements that reduce HepG-2 cells' migration and invasion abilities.

Effect of FABP5 gene silencing on the proliferation, apoptosis and invasion of human gastric SGC-7901 cancer cells

The aim of the present study was to examine the effect of fatty acid binding protein-5 (FABP-5) gene on the proliferation, apoptosis and invasion of human gastric cancer SGC-7901 cells. The viability, apoptosis and cell invasion of SGC-7901 cells before and after FABP5 knockdown were taken as the study objects, design and synthesis of siRNA interference sequence were conducted according to FABP-5 mRNA coding sequences, and SGC-7901 cells were transiently transfected. The human gastric cancer SGC-7901 cells were divided into three groups: FABP-5 siRNA group, negative control group and blank control group. FABP-5 gene mRNA and protein expression levels were detected by RT-PCR and western blot analysis. The CCK-8 assay was used to detect in vitro cell proliferation, flow cytometry (FCM) was used to detect changes in cell cycle and apoptosis in each group, TUNEL staining was used to detect apoptosis in each group, and the cell invasion chamber assay was used to detect cell invasiveness in each group. Each test was repeated three times. The results of the RT-PCR and western blot analysis showed that, expression of FABP-5 mRNA and protein in the FABP-5 siRNA group was significantly decreased compared with the negative and blank control groups. The cell growth rate in the FABP-5 siRNA group was significantly retarded, cell cycle was arrested in G0/G1 phase, the number of cells in S phase was reduced, and compared with the negative and blank control groups, the apoptotic rate in the FABP-5 siRNA group was significantly increased (P<0.01), while proliferation and invasiveness were significantly decreased (P<0.05). In conclusion, specific FABP-5 gene silencing may reduce the invasiveness of gastric cancer cells, inhibit cell proliferation, and arrest cell cycle in G0/G1 phase, resulting in a significant increase in apoptosis.

Quantitative proteomic analysis reveals that proteins required for fatty acid metabolism may serve as diagnostic markers for gastric cancer

BACKGROUND

Gastric cancer is one of the leading causes of cancer-related deaths worldwide. The sensitivities and specificities of current biomarkers for gastric cancer are insufficient for clinical detection, and new diagnostic tests are therefore urgently required.

METHODS

A discovery set of gastric cancer and adjacent normal tissues were analyzed for differentially expressed proteins by labeling of peptide digests with isobaric tag for relative and absolute quantitation (iTRAQ) reagents followed by liquid chromatography-electrospray ionization-tandem mass spectrometry. A validation set of 70 pairs of gastric cancer and adjacent normal tissues were examined to confirm the expression levels of the potential biomarkers identified by iTRAQ labeling.

RESULTS

We detected 431 proteins associated with 16 KEGG pathways that were differentially expressed in gastric cancer tissues, of which 224 were upregulated and 207 were downregulated in gastric cancer tissues. Coexpression of fatty acid binding protein (FABP1) and fatty acid synthase (FASN) in gastric cancer tissues (61.4% sensitivity and 77.1% specificity) was strongly associated with lymph node metastasis and Tumor, Node, Metastasis stage I/II.

CONCLUSION

Quantitative proteomic analysis of gastric cancer tissues revealed that coexpression of FABP1 and FASN may serve as a biomarker for detection of early gastric cancer.

Acyl-coenzyme A-binding protein regulates Beta-oxidation required for growth and survival of non-small cell lung cancer

We identified acyl-coenzyme A-binding protein (ACBP) as part of a proteomic signature predicting the risk of having lung cancer. Because ACBP is known to regulate β-oxidation, which in turn controls cellular proliferation, we hypothesized that ACBP contributes to regulation of cellular proliferation and survival of non-small cell lung cancer (NSCLC) by modulating β-oxidation. We used matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) and immunohistochemistry (IHC) to confirm the tissue localization of ABCP in pre-invasive and invasive NSCLCs. We correlated ACBP gene expression levels in NSCLCs with clinical outcomes. In loss-of-function studies, we tested the effect of the downregulation of ACBP on cellular proliferation and apoptosis in normal bronchial and NSCLC cell lines. Using tritiated-palmitate ((3)H-palmitate), we measured β-oxidation levels and tested the effect of etomoxir, a β-oxidation inhibitor, on proliferation and apoptosis. MALDI-IMS and IHC analysis confirmed that ACBP is overexpressed in pre-invasive and invasive lung cancers. High ACBP gene expression levels in NSCLCs correlated with worse survival (HR = 1.73). We observed a 40% decrease in β-oxidation and concordant decreases in proliferation and increases in apoptosis in ACBP-depleted NSCLC cells as compared with bronchial airway epithelial cells. Inhibition of β-oxidation by etomoxir in ACBP-overexpressing cells produced dose-dependent decrease in proliferation and increase in apoptosis (P = 0.01 and P < 0.001, respectively). These data suggest a role for ACBP in controlling lung cancer progression by regulating β-oxidation.

Fatty acid synthase mediates the epithelial-mesenchymal transition of breast cancer cells

This study aimed to investigate the role of fatty acid synthase (FASN) in the epithelial-mesenchymal transition (EMT) of breast cancer cells. MCF-7 cells and MCF-7 cells overexpressing mitogen-activated protein kinase 5 (MCF-7-MEK5) were used in this study. MCF-7-MEK5 cells showed stable EMT characterized by increased vimentin and decreased E-cadherin expression. An In vivo animal model was established using the orthotopic injection of MCF-7 or MCF-7-MEK5 cells. Real-time quantitative PCR and western blotting were used to detect the expression levels of FASN and its downstream proteins liver fatty acid-binding protein (L-FABP) and VEGF/VEGFR-2 in both in vitro and in vivo models (nude mouse tumor tissues). In MCF-7-MEK5 cells, significantly increased expression of FASN was associated with increased levels of L-FABP and VEGF/VEGFR-2. Cerulenin inhibited MCF-7-MEK5 cell migration and EMT, and reduced FASN expression and down-stream proteins L-FABP, VEGF, and VEGFR-2. MCF-7-MEK5 cells showed higher sensitivity to Cerulenin than MCF-7 cells. Immunofluorescence revealed an increase of co-localization of FASN with VEGF on the cell membrane and with L-FABP within MCF-7-MEK5 cells. Immunohistochemistry further showed that increased percentage of FASN-positive cells in the tumor tissue was associated with increased percentages of L-FABP- and VEGF-positive cells and the Cerulenin treatment could reverse the effect. Altogether, our results suggest that FASN is essential to EMT possibly through regulating L-FABP, VEGF and VEGFR-2. This study provides a theoretical basis and potential strategy for effective suppression of malignant cells with EMT.

Overexpression of FAS and Ki-67 in aberrant crypt foci from patients with adenoma

AIM: To detect the expression of fatty acid synthase (FAS) and Ki-67 in colonic adenoma and aberrant crypt foci to explore their significance in the formation of precancerous lesions.

METHODS: Aberrant crypt foci (ACF) in the rectum of 34 patients with adenoma were identified by magnification chromoendoscopy (MCE) after staining with 0.2% methylene blue solution. Specimens with ACF were biopsied to detect the expression of FAS and Ki-67 by immunohistochemistry.

RESULTS: A total of 166 ACF were found in 31 patients, of which 14 had atypical hyperplasia and 152 had no atypical hyperplasia. The expression of FAS and Ki-67 in colonic adenoma and ACF were significantly higher than that in normal tissue (all P < 0.01). There was no significant difference in the expression of FAS and Ki-67 between ACF with and without dysplasia.

CONCLUSION: The expression of FAS and Ki-67 is higher in colorectal precancerous lesions. FAS may be used as a target for preventing and treating colorectal cancer.

Tumor cell metabolism: an integral view

Cancer is a genetic disease that is caused by mutations in oncogenes, tumor suppressor genes and stability genes. The fact that the metabolism of tumor cells is altered has been known for many years. However, the mechanisms and consequences of metabolic reprogramming have just begun to be understood. In this review, an integral view of tumor cell metabolism is presented, showing how metabolic pathways are reprogrammed to satisfy tumor cell proliferation and survival requirements. In tumor cells, glycolysis is strongly enhanced to fulfill the high ATP demands of these cells; glucose carbons are the main building blocks in fatty acid and nucleotide biosynthesis. Glutaminolysis is also increased to satisfy NADPH regeneration, whereas glutamine carbons replenish the Krebs cycle, which produces metabolites that are constantly used for macromolecular biosynthesis. A characteristic feature of the tumor microenvironment is acidosis, which results from the local increase in lactic acid production by tumor cells. This phenomenon is attributed to the carbons from glutamine and glucose, which are also used for lactic acid production. Lactic acidosis also directs the metabolic reprogramming of tumor cells and serves as an additional selective pressure. Finally, we also discuss the role of mitochondria in supporting tumor cell metabolism.

Indole-3-carbinol inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone plus benzo(a)pyrene-induced lung tumorigenesis in A/J mice and modulates carcinogen-induced alterations in protein levels

We tested the chemopreventive efficacy of indole-3-carbinol (I3C), a constituent of Brassica vegetables, and its major condensation product, 3,3'-diindolylmethane (DIM), against lung tumorigenesis induced by a mixture of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (BaP) in A/J mice. The mixture of NNK plus BaP (2 micromol each) was administered by gavage as eight weekly doses, whereas I3C (112 micromol/g diet) and DIM (2 and 30 micromol/g diet in experiments 1 and 2, respectively) were given in the diet for 23 weeks beginning at 50% of carcinogen treatment. I3C reduced NNK plus BaP-induced tumor multiplicity by 78% in experiment 1 and 86% in experiment 2; the respective reductions in tumor multiplicity by DIM were 5% and 66%. Using a quantitative proteomics method, isobaric tags for relative and absolute quantitation (iTRAQ) coupled with mass spectrometry, we identified and quantified at least 250 proteins in lung tissues. Of these proteins, nine showed differences in relative abundance in lung tissues of carcinogen-treated versus untreated mice: fatty acid synthase, transketolase, pulmonary surfactant-associated protein C (SP-C), L-plastin, annexin A1, and haptoglobin increased, whereas transferrin, alpha-1-antitrypsin, and apolipoprotein A-1 decreased. Supplementation of the diet of carcinogen-treated mice with I3C reduced the level of SP-C, L-plastin, annexin A1, and haptoglobin to that of untreated controls. These results were verified using immunoblotting. We show here that tumor-associated signature proteins are increased during NNK plus BaP-induced lung carcinogenesis, and I3C inhibits this effect, suggesting that the lung tumor chemopreventive activity of I3C might be related to modulation of carcinogen-induced alterations in protein levels.