Fatty acid binding protein 5 is a novel therapeutic target for hepatocellular carcinoma

BACKGROUND Hepatocellular carcinoma(HCC)is an aggressive subtype of liver cancer and is one of the most common cancers with high mortality worldwide.Reprogrammed lipid metabolism plays crucial roles in HCC cancer cell survival,growth,and evolution.Emerging evidence suggests the importance of fatty acid binding proteins(FABPs)in contribution to cancer progression and metastasis;however,how these FABPs are dysregulated in cancer cells,especially in HCC,and the roles of FABPs in cancer progression have not been well defined.AIM To understand the genetic alterations and expression of FABPs and their associated cancer hallmarks and oncogenes in contributing to cancer malignancies.METHODS We used The Cancer Genome Atlas datasets of pan cancer and liver hepatocellular carcinoma(LIHC)as well as patient cohorts with other cancer types in this study.We investigated genetic alterations of FABPs in various cancer types.mRNA expression was used to determine if FABPs are abnormally expressed in tumor tissues compared to non-tumor controls and to investigate whether their expression correlates with patient clinical outcome,enriched cancer hallmarks and oncogenes previously reported for patients with HCC.We determined the protein levels of FABP5 and its correlated genes in two HCC cell lines and assessed the potential of FABP5 inhibition in treating HCC cells.RESULTS We discovered that a gene cluster including five FABP family members(FABP4,FABP5,FABP8,FABP9 and FABP12)is frequently co-amplified in cancer.Amplification,in fact,is the most common genetic alteration for FABPs,leading to overexpression of FABPs.FABP5 showed the greatest differential mRNA expression comparing tumor with non-tumor tissues.High FABP5 expression correlates well with worse patient outcomes(P<0.05).FABP5 expression highly correlates with enrichment of G2M checkpoint(r=0.33,P=1.1e-10),TP53 signaling pathway(r=0.22,P=1.7e-5)and many genes in the gene sets such as CDK1(r=0.56,P=0),CDK4(r=0.49,P=0),and TP53(r=0.22,P=1.6e-5).Furthermore,FABP5 also correlates well with two co-expressed oncogenes PLK1 and BIRC5 in pan cancer especially in LIHC patients(r=0.58,P=0;r=0.58,P=0;respectively).FABP5high Huh7 cells also expressed higher protein levels of p53,BIRC5,CDK1,CDK2,and CDK4 than FABP5low HepG2 cells.FABP5 inhibition more potently inhibited the tumor cell growth in Huh7 cells than in HepG2 cells.CONCLUSION We discovered that FABP5 gene is frequently amplified in cancer,especially in HCC,leading to its significant elevated expression in HCC.Its high expression correlates well with worse patient outcome,enriched cancer hallmarks and oncogenes in HCC.FABP5 inhibition impaired the cell viability of FABP5high Huh7 cells.All these support that FABP5 is a novel therapeutic target for treating FABP5high HCC.

Expression and Characterization of Human Heart Type Fatty Acid Binding Protein in Pichia Pastoris

H-FABP is regarded as a tissue-specific protein existing only in myocardial cells. It is released from the cardiac tissue and gets into the plasma when a heart attack occurs; the myocardial infarction is a good case in point. As a resuit, the detection of H-FABP will be an early and important biomarker for the disease concerned. The objective of the study is to prepare the recombinant H-FABP by aeukaryotic expression system, pichia, to produce the protein mimicking natural H-FABP, as an immunogen for the production of the specific antibody. A gene fragment encoding H-FABP was cloned in the expressing vector pPICZα, after sequencing. The recombinant plasmid was transformed into the competent cells of the X-33 strain by means of electroporation. The expression of the target peptide induced by methanol was screened by means of Western hlotting, with the available MAb（Clone 6B6）. Highly expressive engineer strains were obtained. The production of recombinant H-FABP under induction was about 0.7 g/L, with an Mr of 14.5 kDa and recognized by a commercially available MAb （Clone 6B6）. The recombinant vector was successfully constructed. Following this, H-FABP was expressed in X-33, and it would become the source of the preparation of specific antibodies, to develop diagnostic kits.

The impact of codon 54 variation in intestinal fatty acid binding protein gene on the pathogenesis of diabetes mellitus in Chinese

Objective To investigate whether or not the intestinal fatty acid binding protein gene (FABP2) Ala54Thr variation is related to non insulin dependent diabetes mellitus (NIDDM), obesity, dyslipidemia and glucose stimulated insulin secretion (GSIS) in Chinese.Methods The FABP2 Ala54Thr variation was detected by PCR/HhaI digestion in 231 Chinese subjects (116 with normal glucose tolerance (NGT), 54 with impaired glucose tolerance (IGT) and 61 with NIDDM). Plasma glucose, insulin and C peptide levels before and after 75 g glucose load as well as fasting lipid profile were determined.Results (1) The Ala54 and Thr54 allele frequencies in Chinese were 0.71 and 0.29 respectively; (2) The FABP2 Ala54Thr variation was neither associated with fasting and post challenged plasma glucose levels nor with NIDDM; (3) This variation was neither associated with fasting lipid profile nor with obesity; (4) The IGT subjects with genotype Thr54(+) (Thr54 homozygotes and heterozygotes) had lower fasting, 2 hour and total C peptide levels and smaller AUC representing lesser C peptide secretion after glucose challenge than those with genotype Thr54( ) (Ala54 homozygotes) (P= 0.04 , 0.03, 0.01 and 0.01 respectively). The serum insulin levels changed in the same tendency.Conclusions The glucose stimulated insulin secretion (GSIS) reserve of islet beta cells is more limited in subjects with FABP2 Thr54(+) genotype than in those with FABP2 Thr54(-) genotype. It suggests that FABP2 codon 54 variation might contribute to the insufficient insulin secretion in the development of NIDDM in Chinese.

Specific protein-urea interactions

The mechanism of urea's action in protein denaturation remains largely unknown.To provide an experimental basis for molecular dynamics(MD)simulations on urea-protein interactions,we investigated the effect of urea on human intestinal fatty acid binding protein(hIFABP)by nuclear magnetic resonance(NMR).Hydrogen-deuterium exchange(HDX)rates at
2 M urea indicate that urea affects hIFABP in a residue-specific manner via direct urea-protein interactions and preferentially weakens hydrogen bonds between highly protected amides.Residue-specific effects of urea on NMR peak intensities and chemical shifts further support the presence of direct urea-protein interactions.Twodimensional(2D)water-rotating frame Overhauser enhancement(ROE)data shows one protein-bound water molecule in contact with Val66 and Trp82,one putative bound water molecule in interaction with Thr76 and E-F loop,and that urea at low concentrations cannot displace these protein-bound water molecules.Our urea-nuclear Overhauser effect(NOE)experiments using 15N-urea further show no tightly protein-bound urea molecules.Our results thus suggest specific,but weak or transient,urea-protein interactions,supporting the direct interaction model of urea denaturation.

Combined assessment of myocardial damage and electrical disturbance in chronic heart failure

AIM To investigate feasibility of combined assessment of biochemical and electrophysiological myocardial impairment markers risk-stratifying patients with chronic heart failure(CHF). METHODS Serum levels of heart-type fatty acid binding protein(H-FABP) as a marker of ongoing myocardial damage and QRS duration on electrocardiogram were measured at admission in 322 consecutive patients with CHF. A prolonged QRS duration was defined as 120 ms or longer. The cut-off value for H-FABP level(4.5 ng/mL) was determined from a previous study. Patients were prospectively followed during a median follow up period of 534 d. The primary endpoint was cardiac deaths and rehospitalization for worsening CHF.RESULTS There were 117 primary events, including 27 cardiac deaths and 90 rehospitalizations. Patients were stratified into four groups according to H-FABP level and QRS duration(≥ 120 ms). Multivariate analysis demonstrated that high H-FABP levels [hazard ratio(HR) = 1.745, P = 0.021] and QRS prolongation(HR1.612, P = 0.0258) were independent predictors of cardiac events. Kaplan-Meier analysis demonstrated that the combination of high H-FABP levels and QRS prolongation could be used to reliably stratify patients at high risk for cardiac events(log rank test P < 0.0001).CONCLUSION Combined assessment of myocardial damage and electrical disturbance can be used to risk-stratify patients with CHF.

Research progress on markers of urine tubular damage in idiopathic membranous nephropathy

Idiopathic membranous nephropathy is a common primary glomerular disease.Recently,it has been found that the progression and prognosis of glomerular diseases are not only related to the glomeruli itself,but also to the severity of renal tubular injury.Although blood creatinine and urinary protein are recognized biomarkers,they appear late,are insensitive,lack specificity,and are difficult to respond to IMN conditions in a timely and accurate manner.Markers such as N-acetyl-β-D-glucosaminidase,kidney injury molecule 1,neutrophil gelatinase-associated lipoprotein in urine can dynamically reflect the progress of kidney injury in the early stage,and are detected as noninvasive,so It has been applied in IMN,but such research is lacking,and the scope needs to be further expanded and discussed in depth.

心肌特异性脂肪酸结合蛋白在不停跳冠状动脉搭桥术中的变化

Objective To appraise the sensitivity of hFABP for myocardial ischemia in patients undergoing off-pump coronary artery bypass grafting among cardiac markers. Methods Thirty-eight consecutive patients undergoing OPCABG were included in a randomized study using standardized operative procedures and myocardial protection. Serial blood samples were taken preoperatively, during anastomoses, at the end of operation, 6 h, 18 h and 36 h postoperatively and tested for hFABP、Troponin I (cTnI)、sCD40L、creatine kinase isoenzyme (CK-MB). Results Six cases (16.7%) were found myocardial injury during the OPCABG by ECG or PAP. Their serial serum hFABP,cTnI,sCD40L,CK-MB were higher than those without myocardial injury. The peak serum level of hFABP was higher and occurred earlier than those of cTnI,sCD40L,CK-MB. Conclusion These results suggest that serum hFABP is an early and sensitive biochemical marker for the diagnosis of myocardial injury in patients undergoing OPCABG.

Clinical signifi cance of FABP2 expression in newborns with necrotizing enterocolitis

Background: This meta-analysis aimed to determinethe role of human fatty acid binding protein 2 (FABP2)expression in the diagnosis of necrotizing enterocolitis(NEC) of newborns.Data sources: Eligible studies for further statisticalanalysis were identified from various databases including PubMed, Expert Medica Database, Web of Science,Cochrane Library, Google Scholar, China BioMedicineand China National Knowledge Infrastructure. Randomeffects model was used, and summary standardized meandifference (SMD) with its 95% confi dence interval (CI) wascalculated to assess the association of FABP2 expressionand NEC.Results: Ten articles which included 572 infants (262infants with NEC and 310 healthy controls) were includedin the current meta-analysis. FABP2 showed a positiverelationship with NEC of newborns (SMD=2.88, 95%CI=2.09-3.67, P<0.001). And FABP2 expression washigher in patients with advanced stage of NEC (stage IIIor stage II+III) than in those with early stage of NEC(stage I) (SMD=-0.48, 95% CI=-0.87 to -0.09, P=0.015).Ethnicity-stratifi ed analysis yielded signifi cantly differentestimates with a high FABP2 expression in NEC in bothCaucasians (SMD=3.16, 95% CI=1.90-4.43, P<0.001) andAsians (SMD=2.57, 95% CI=1.50-3.64, P<0.001). Samplebasedsubgroup analysis showed that FABP2 expressionwas positively correlated with neonatal NEC in bothurinary- and blood-sample subgroups (all P<0.05).Conclusion: The results prove that the high FABP2expression is related to the damage to intestinal cells,which may be a possible early detection marker identifyingneonatal NEC.