Fatty Acid Binding Protein 5 Overexpression Research Articles

High levels of fatty acid-binding protein 5 excessively enhances fatty acid synthesis and proliferation of granulosa cells in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is one of the most complex endocrine disorders in women of reproductive age. Abnormal proliferation of granulosa cells (GCs) is an important cause of PCOS. This study aimed to explore the role of fatty acid-binding protein 5 (FABP5) in granulosa cell (GC) proliferation in polycystic ovary syndrome (PCOS) patients. The FABP5 gene, which is related to lipid metabolism, was identified through data analysis of the gene expression profiles of GSE138518 from the Gene Expression Omnibus (GEO) database. The expression levels of FABP5 were measured by quantitative real-time PCR (qRT‒PCR) and western blotting. Cell proliferation was evaluated with a cell counting kit-8 (CCK-8) assay. Western blotting was used to assess the expression of the proliferation marker PCNA, and immunofluorescence microscopy was used to detect Ki67 expression. Moreover, lipid droplet formation was detected with Nile red staining, and qRT‒PCR was used to analyze fatty acid storage-related gene expression. We found that FABP5 was upregulated in ovarian GCs obtained from PCOS patients and PCOS mice. FABP5 knockdown suppressed lipid droplet formation and proliferation in a human granulosa-like tumor cell line (KGN), whereas FABP5 overexpression significantly enhanced lipid droplet formation and KGN cell proliferation. Moreover, we determined that FABP5 knockdown inhibited PI3K-AKT signaling by suppressing AKT phosphorylation and that FABP5 overexpression activated PI3K-AKT signaling by facilitating AKT phosphorylation. Finally, we used the PI3K-AKT signaling pathway inhibitor LY294002 and found that the facilitation of KGN cell proliferation and lipid droplet formation induced by FABP5 overexpression was inhibited. In contrast, the PI3K-AKT signaling pathway agonist SC79 significantly rescued the suppression of KGN cell proliferation and lipid droplet formation caused by FABP5 knockdown. FABP5 promotes active fatty acid synthesis and excessive proliferation of GCs by activating PI3K-AKT signaling, suggesting that abnormally high expression of FABP5 in GCs may be a novel biomarker or a research target for PCOS treatment.

CNSC-23. ROLE OF GLIAL PH-DEPENDENT METABOLIC REGULATION IN GLIOMA PROGRESSION

Abstract Malignant glioma is a devastating brain cancer with barely any improvement in prognosis over decades. One key mechanism for glioma invasiveness is the dynamic metabolic communication between glioma and surrounding cells shaping the tumor microenvironment. While extracellular acidosis is a pathological hallmark of glioma, pH-dependent mechanisms underlying tumor metabolic reprogramming remain poorly defined. Our study focuses on a glial-enriched sodium-bicarbonate cotransporter, Slc4a4, which was previously identified as intracellular and extracellular pH regulator. While Slc4a4-mediated pH regulation is important for physiological brain function and responses after injury, its role in glioma progression is largely undefined. To begin addressing this question, we analyzed The Cancer Genome Atlas (TCGA) database, finding high Slc4a4 expression correlates with prolonged survival in glioma patients. Corroboratively, Slc4a4 gain-of-function (GOF) drastically decreases tumorigenesis and angiogenesis in patient-derived-xenograft and CRISPR-mediated de novo mouse glioma models. These results are further complemented by loss-of-function (LOF) studies using glial-specific Slc4a4 knockout mice, suggesting an inhibitory role of Slc4a4 in glioma growth and associated angiogenesis. A combination of unbiased metabolomic and cancer-targeted proteomic profiling of Slc4a4 GOF/LOF mouse glioma reveals an inverse correlation between Slc4a4 and a key lipid metabolism protein, FABP5 (Fatty Acid Binding Protein 5), which is coupled with dysregulated lipid metabolism. Moreover, analysis of TCGA database shows inverse expression and survival correlation of Slc4a4 and FABP5 in glioma patients. Further functional study shows that overexpression of FABP5 reverses Slc4a4’s inhibitory effects on glioma growth in immunocompetent mouse glioma model, supporting a functional antagonism between Slc4a4 and FABP5. Together, our study indicates that Slc4a4 plays a protective role in glioma progression by regulating metabolic activities, providing critical insights into pH-dependent metabolic reprogramming in glioma.

FABP5 regulates lipid metabolism to facilitate pancreatic neuroendocrine neoplasms progression via FASN mediated Wnt/β-catenin pathway.

Pancreatic neuroendocrine neoplasms (pNENs) are among the most frequently occurring neuroendocrine neoplasms (NENs) and require targeted therapy. High levels of fatty acid binding protein 5 (FABP5) are involved in tumor progression, but its role in pNENs remains unclear. We investigated the mRNA and protein levels of FABP5 in pNEN tissues and cell lines and found them to be upregulated. We evaluated changes in cell proliferation using CCK-8, colony formation, and 5-ethynyl-2'-deoxyuridine assays and examined the effects on cell migration and invasion using transwell assays. We found that knockdown of FABP5 suppressed the proliferation, migration, and invasion of pNEN cell lines, while overexpression of FABP5 had the opposite effect. Co-immunoprecipitation experiments were performed to clarify the interaction between FABP5 and fatty acid synthase (FASN). We further showed that FABP5 regulates the expression of FASN via the ubiquitin proteasome pathway and both proteins facilitate the progression of pNENs. Our study demonstrated that FABP5 acts as an oncogene by promoting lipid droplet deposition and activating the WNT/β-catenin signaling pathway. Moreover, the carcinogenic effects of FABP5 can be reversed by orlistat, providing a novel therapeutic intervention option.

Absence of the fatty acid binding protein5 (FABP5) inhibits the establishment of resident memory T cells after a secondary Listeria monocytogenes infection

Abstract Fatty acid binding protein 5 (FABP5) is a member of the family of fatty acid binding proteins involved in fatty acid uptake, transport, and metabolism. FABP5 is ubiquitously expressed, including in T cells. During the course of an immune reaction, T cells undergo multiple changes to their metabolism. Once naïve T cells are activated, expansion is triggered, and cells differentiate to become effector cells accompanied by a metabolic change from fatty acid oxidation to glycolysis. Once the pathogen is eliminated, effector cells differentiate into memory cells, with central memory (TCM) and effector memory (TEM) cells surveying the circulation and resident memory (TRM) cells establishing a tissue memory pool that can quickly react to localized reinfection. These TRM cells are thought to rely on lipid uptake and fatty acid oxidation for survival. We wanted to investigate the effect of FABP5 on the development of CD8+ TRM cells in the context of a Listeria monocytogenes (Lm) infection. We had previously shown that the lack of FABP5 leads to a resistance to Lm in mice after a single infection, while the overexpression of FABP5 showed increased mortality and bacterial burden. Here, we used WT and FABP5−/− mice in an infection model with Lm-Ova to analyze the innate and antigen-specific adaptive immune responses. To this end, WT and FABP5−/− mice were infected i.v. with Lm-Ova and their immune responses analyzed at various days after. We show that while the primary immune response is improved in FABP5−/−, there was a profound negative effect on the secondary response. This was based on a severe reduction of Ova-specific TRM in the liver while TCM and TEM populations were unaffected. Flow analyses and functional assays taken throughout will be presented. Supported by NHlDI 1R01HL141264 Supported by NHlDI 1R01HL141264

Abstract 1266: Discovery and preclinical evaluation of a novel covalent inhibitor of FABP5 for cancer therapy

Abstract Dysregulated fatty acid metabolism is thought to be a hallmark of cancer, wherein fatty acids function both as an energy source and as signals for enzymatic and transcriptional networks contributing to malignancy. Fatty acid-binding protein 5 (FABP5) is an intracellular protein that facilitates transport of fatty acids and plays a role in regulating the expression of genes associated with cancer progression such as cell growth, survival, and metastasis. Overexpression of FABP5 has been reported to contribute to an aggressive phenotype and a poor survival correlation in several cancers. Therefore, inhibition of FABP5 is considered as a therapeutic approach for cancers. Phenotypic screening of a library of covalent compounds for selective sensitivity of cancer cells followed by medicinal chemistry optimization resulted in the identification of AUR104 with desirable properties. Chemoproteomic-based target deconvolution revealed FABP5 as the cellular target of AUR104. Covalent adduct formation with Cys43 of FABP5 by AUR104 was confirmed by mass spectrometry. Target occupancy studies using a biotin-tagged AUR104 demonstrated potent covalent binding to FABP5 in both cell-free and cellular conditions. Ligand displacement assay with a fluorescent fatty acid probe confirmed the competitive binding mode of AUR104 with fatty acids. Binding at the fatty acid site and covalent bond formation with Cys43 were also demonstrated by crystallography. Furthermore, AUR104 showed a high degree of selectivity against a broad safety pharmacology panel of enzymes and receptors. AUR104 exhibited potent anti-proliferative activity in a large panel of cell lines derived from both hematological and solid cancers with a high degree of selectivity over normal cells. Anti-proliferative activity in lymphoma cell lines correlated with inhibition of MALT1 pathway activity, cleavage of RelB/Bcl10 and secretion of cytokines, IL-10 and IL-6. AUR104 displayed desirable drug-like properties and dose-dependent oral exposure in pharmacokinetic studies. Oral dosing with AUR104 resulted in dose-dependent anti-tumor activity in DLBCL (OCI-LY10) and NSCLC (NCI-H1975) xenograft models. In a repeated dose MTD studies in rodents and non-rodents, AUR104 showed good tolerability with an exposure multiple of >500 over cellular EC50 for up to 8 hours. In summary, we have identified a novel covalent FABP5 inhibitor with optimized properties that showed anti-tumor activity in in vitro and in vivo models with acceptable safety profile. The data presented here strongly support clinical development of AUR104. Citation Format: Dinesh Chikkanna, Leena Khare Satyam, Sunil Kumar Pnaigrahi, Vinayak Khairnar, Manoj Pothuganti, Lakshmi Narayan Kaza, Narasimha Raju Kalidindi, Vijaya Shankar Nataraj, Aditya Kiran Gatta, Narasimha Rao Krishnamurthy, Sandeep Patil, DS Samiulla, Kiran Aithal, Vijay Kamal Ahuja, Nirbhay Kumar Tiwari, KB Charamannna, Pravin Pise, Thomas Anthony, Kavitha Nellore, Sanjeev Giri, Shekar Chelur, Susanta Samajdar, Murali Ramachandra. Discovery and preclinical evaluation of a novel covalent inhibitor of FABP5 for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1266.

FABP5 enhances malignancies of lower‐grade gliomas via canonical activation of NF‐κB signaling

Low‐grade gliomas (LGGs) are grade III gliomas based on the WHO classification with significant genetic heterogeneity and clinical properties. Traditional histological classification of gliomas has been challenged by the improvement of molecular stratification; however, the reproducibility and diagnostic accuracy of LGGs classification still remain poor. Herein, we identified fatty acid binding protein 5 (FABP5) as one of the most enriched genes in malignant LGGs and elevated FABP5 revealed severe outcomes in LGGs. Functionally, lentiviral suppression of FABP5 reduced malignant characters including proliferation, cloning formation, immigration, invasion and TMZ resistance, contrarily, the malignancies of LGGs were enhanced by exogenous overexpression of FABP5. Mechanistically, epithelial‐mesenchymal transition (EMT) was correlated to FABP5 expression in LGGs and tumour necrosis factor α (TNFα)‐dependent NF‐κB signalling was involved in this process. Furthermore, FABP5 induced phosphorylation of inhibitor of nuclear factor kappa‐B kinase α (IKKα) thus activated nuclear factor kappa‐B (NF‐κB) signalling. Taken together, our study indicated that FABP5 enhances malignancies of LGGs through canonical activation of NF‐κB signalling, which could be used as individualized prognostic biomarker and potential therapeutic target of LGGs.

Understanding the Interplay between Human Epidermal Growth Factor Receptor 2 and Neuraminidase 1 on the Regulation of Fatty Acid Binding Protein 5 in Breast Cancer Cells

Human epidermal growth factor receptor 2 (HER2), a member of the epidermal growth factor receptor (EGFR) family, accounts for 15–20% of breast cancer cases. HER2 is a glycosylated protein with sialic acid groups attached on the surface of the protein. Sialylated proteins can be regulated by enzymes called Neuraminidases 1 (Neu1) that catalyze the removal of sialic acid residues from glycoproteins. One of the oncogenes activated by the downstream signaling effector of the HER2 pathway is a protein called fatty acid binding protein 5 (FABP5). Elevated expression of FABP5 is correlated with poor prognosis in several carcinomas and overexpression of FABP5 prevents retinoic acid‐mediated growth suppression of mammary carcinoma cells. The objective of this study is to examine whether reducing Neu1 activity or its expression decreases HER2 activation and subsequently the downregulation of FABP5 in HER2 positive breast cancer cell line, MDA‐MB‐453. Using sialic acid assay, we quantitated the levels of sialic acid in MDA‐MB‐453 cells treated with oseltamivir phosphate, an inhibitor of Neu1 activity. Oseltamivir phosphate reduced the concentration of sialic acid in a dose‐dependent manner. Through western blot analysis, we demonstrated that suppressing the activity of Neu1 with ostelamivir phosphate in MDA‐MB‐453 cells reduced heregulin‐mediated induction of the active phosphorylated HER2 and its downstream target, FABP5. Furthermore, silencing Neu1 using siRNA reduced the expression of FABP5 protein expression in MDA‐MB‐453. Taken together, this data demonstrated that inhibition of Neu1 prevented heregulin‐induced HER2 activation, and in turn, regulated the expression of FABP5 in MDA‐MB‐453 cell line. We propose that these studies will contribute to the understanding of how Neu1 and HER2 communicate to modulate the expression of FABP5, Thus, Neu1 can be used as clinical target to improve the efficacy or sensitivity of retinoic acid in HER2+ breast cancer patients.Support or Funding InformationFunding was obtained through the Summer Undergraduate Research Fellowship, Office of Undergraduate Research (I.M) and the Pat Capps Covey College of Allied Health Professions Start Up Fund (P.T.) from the University of South Alabama.

Clinical relevance of gene expression in localized and metastatic prostate cancer exemplified by FABP5.

Fatty acid-binding protein 5 (FABP5), a transport protein for lipophilic molecules, has been proposed as protein marker in prostate cancer (PCa). The role of FABP5 gene expression is merely unknown. In two cohorts of PCa patients who underwent radical prostatectomy (n = 40 and n = 57) and one cohort of patients treated with palliative transurethral resection of the prostate (pTUR-P; n = 50) FABP5 mRNA expression was analyzed with qRT-PCR. Expression was correlated with clinical parameters. BPH tissue samples served as control. To independently validate findings on FABP5 expression, three microarray and sequencing datasets were reanalyzed (MSKCC 2010 n = 216; TCGA 2015 n = 333; mCRPC, Nature Medicine 2016 n = 114). FABP5 expression was correlated with ERG-fusion status, TCGA subtypes, cancer driver mutations and the expression of druggable downstream pathway components. FABP5 was overexpressed in PCa compared to BPH in the cohorts analyzed by qRT-PCR (radical prostatectomy p = 0.003, p = 0.010; pTUR-P p = 0.002). FABP5 expression was independent of T stage, Gleason Score, nodal status and PSA level. FABP5 overexpression was associated with the absence of TMPRSS2:ERG fusion (p < 0.001 in TCGA and MSKCC). Correlation with TCGA subtypes revealed FABP5 overexpression to be associated with SPOP and FOXA1 mutations. FABP5 was positively correlated with potential drug targets located downstream of FABP5 in the PPAR-signaling pathway. FABP5 overexpression is frequent in PCa, but seems to be restricted to TMPRESS2:ERG fusion-negative tumors and is associated with SPOP and FOXA1 mutations. FABP5 overexpression appears to be indicative for increased activity in PPAR signaling, which is potentially druggable.

Abstract 372: Obesity matters: Prostate cancers that overexpress fatty acid binding protein 5 are more common in men who are overweight or obese

Abstract BACKGROUND: One of the hallmarks of the malignant phenotype is an increase in the cell's demand for fatty acids (FA). Many cancers, including prostate cancer, show increased expression of fatty acid synthase (FASN), a multi-component enzyme that catalyzes the de novo synthesis of the fatty acid palmitate. However recent observations suggest that alternate mechanisms for FA acquisition are also important, including the utilization of exogenous palmitate when it's available. Recently, through a biopsy-based molecular analysis of high risk prostate cancer, we identified a tumor subtype with very high (&amp;gt;10 fold) "outlier" overexpression of fatty acid binding protein 5 (FABP5). FABP5 is involved in lipid transport and signaling, and it facilitates the utilization of palmitate and other FAs from outside of the cell. De novo palmitate synthesis by the FASN pathway is energetically expensive compared to utilization of exogenous fatty acids. STUDY DESIGN: We proposed that prostate cancers that can efficiently utilize exogenous palmitate are at a selective advantage when dietary FAs are abundant. In this study, to test that hypothesis, we compared FABP5 and FASN expression levels in prostate cancers obtained from diagnostic biopsies from normal weight, overweight and obese study subjects. A total of 201 consecutive eligible prostate biopsy patients were prospectively enrolled; 151 (75%) of these patients were cancer positive. Prostate cancer FABP5 and FASN mRNA expression were measured by qrtPCR and FABP5/FASN and FASN/FABP5 expression ratios were determined for each cancer positive core. BMI and self-identified race were obtained from hospital records. RESULTS: The expression of FABP5 and the FABP5/FASN expression ratio were significantly higher in overweight and obese individuals compared to normal weight individuals (mean FABP5/FASN overexpression ratio of 20.2 in overweight/obese subjects vs 4.0 in normal weight subjects; p &amp;lt; 0.05). The highest levels of prostate cancer FABP5 outlier overexpression (FABP5/FASN &amp;gt; 100) were observed in African American subjects with BMI &amp;gt; 30, and high levels of FABP5 outlier overexpression were more strongly associated with overall Gleason sum in African American than in European American subjects. CONCLUSIONS: In our study population, prostate cancer subtypes with high levels of FABP5 overexpression were more common in biopsy patients who were overweight or obese compared to normal weight patients. The highest levels of FABP5 overexpression in were observed in prostate cancers from obese African American subjects. Such FABP5 dominant prostate cancers may utilize exogenous fatty acids more efficiently and be more sensitive to dietary interventions than the more widely studied FASN dominant prostate cancers. Funding: DOD Prostate Cancer Research Program Awards W8XWH-10-1-0543 (Grizzle, PI) and W81XWH-10-1-0544 (Gaston, PI) Citation Format: Sandra M. Gaston, Soroush Rais-Bahrami, James Kearns, Dennis Otali, Denise Oelschlager, Mark S. DeGuenther, Jeffrey W. Nix, Peter N. Kolettis, James E. Bryant, Robert A. Oster, William E. Grizzle. Obesity matters: Prostate cancers that overexpress fatty acid binding protein 5 are more common in men who are overweight or obese [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 372.

MP29-15 MAKE IT FROM SCRATCH OR HAVE IT DELIVERED? SATISFYING THE FATTY ACID DEMAND OF PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I1 Apr 2018MP29-15 MAKE IT FROM SCRATCH OR HAVE IT DELIVERED? SATISFYING THE FATTY ACID DEMAND OF PROSTATE CANCER Sandra Gaston, Soroush Rais-Bahrami, Jeffrey Nix, Peter Kolettis, James Bryant, James Kearns, Oelschlager Denise, Dennis Otali, and William Grizzle Sandra GastonSandra Gaston More articles by this author , Soroush Rais-BahramiSoroush Rais-Bahrami More articles by this author , Jeffrey NixJeffrey Nix More articles by this author , Peter KolettisPeter Kolettis More articles by this author , James BryantJames Bryant More articles by this author , James KearnsJames Kearns More articles by this author , Oelschlager DeniseOelschlager Denise More articles by this author , Dennis OtaliDennis Otali More articles by this author , and William GrizzleWilliam Grizzle More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.935AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES One of the hallmarks of the malignant phenotype is an increase in the cell's demand for fatty acids (FA). Many cancers, including prostate cancer (PrCa), show increased expression of fatty acid synthase (FASN), a multi-component enzyme that catalyzes the de novo synthesis of the FA palmitate. However recent observations suggest that alternate mechanisms for FA acquisition are also important, including the utilization of exogenous palmitate when it's available. Recently, through a biopsy-based molecular analysis of high risk PrCa, we identified a tumor subtype with very high (>10 fold) "outlier" overexpression of fatty acid binding protein 5 (FABP5). FABP5 is involved in lipid transport and signaling, and it facilitates the utilization of palmitate and other FAs from outside of the cell. De novo palmitate synthesis by the FASN pathway is energetically expensive compared to utilization of exogenous FAs. We propose that PrCas that can efficiently utilizes exogenous palmitate are at a selective advantage when dietary FAs are abundant. In this study, to test that hypothesis, we compared FABP5 and FASN expression levels in PrCas obtained from diagnostic biopsies from normal weight, overweight and obese study subjects. METHODS A total of 201 consecutive eligible prostate biopsy patients were prospectively enrolled; 151 (75%) of these patients were cancer positive. PrCa FABP5 and FASN mRNA expression were measured by qrtPCR and FABP5/FASN and FASN/FABP5 expression ratios were determined for each cancer positive core. BMI and self-identified race were obtained from hospital records. RESULTS The expression of FABP5 and the FABP5/FASN expression ratio were significantly higher in overweight and obese individuals compared to normal weight individuals (mean FABP5/FASN overexpression ratio of 20.2 in overweight/obese subjects vs 4.0 in normal weight subjects; p < 0.05). The highest levels of PrCa FABP5 outlier overexpression (FABP5/FASN > 100) were observed in African American subjects with BMI > 30. CONCLUSIONS Our results are consistent with a growing body of evidence suggesting that the well-recognized "addiction" of PrCa for FA can be satisfied by more than one mechanism. In our study population, PrCa subtypes with high levels of FABP5 overexpression were more common in biopsy patients who were overweight or obese. Such FABP5 dominant PrCa subtypes may be more sensitive to dietary interventions than the more widely studied FASN dominant PrCas. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e371 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Sandra Gaston More articles by this author Soroush Rais-Bahrami More articles by this author Jeffrey Nix More articles by this author Peter Kolettis More articles by this author James Bryant More articles by this author James Kearns More articles by this author Oelschlager Denise More articles by this author Dennis Otali More articles by this author William Grizzle More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

The Role of FABP5 in Radiation-Induced Human Skin Fibrosis.

Radiation-induced skin fibrosis is a detrimental and chronic disorder that occurs after radiation exposure. The molecular changes underlying the pathogenesis of radiation-induced fibrosis of human skin have not been extensively reported. Technical advances in proteomics have enabled exploration of the biomarkers and molecular pathogenesis of radiation-induced skin fibrosis, with the potential to broaden our understanding of this disease. In this study, we compared protein expression in radiation-induced fibrotic human skin and adjacent normal tissues using iTRAQ-based proteomics technology. We identified 186 preferentially expressed proteins (53 upregulated and 133 downregulated) between radiogenic fibrotic and normal skin tissues. The differentially expressed proteins included keratins (KRT5, KRT6A, KRT16 and KRT17), caspase-14, fatty acid-binding protein 5 (FABP5), SLC2A14 and resistin. Through bioinformatic analysis of the proximal promoters, common motifs and corresponding transcriptional factors were identified that associate with the dysregulated proteins, including PAX5, TBX1, CLOCK and AP2D. In particular, FABP5 (2.15-fold increase in fibrotic skin tissues), a transporter of hydrophobic fatty acids, was investigated in greater detail. Immunohistochemistry confirmed that the protein level of FABP5 was increased in fibrotic human skin tissues, especially in the epidermis. Overexpression of FABP5 resulted in nuclear translocation of SMAD2 and significant activation of the profibrotic TGF-β signaling pathway in human fibroblast WS1 cells. Moreover, exogenous FABP5 (FABP5-EGFP) could be incorporated by skin cells and intensify TGF-β signaling, indicating a communication between the microenvironment and skin fibrosis. Taken together, our findings illustrate the molecular changes during radiation-induced human skin fibrosis and the critical role of FABP5 in activating the TGF-β signaling pathway.

Abstract 457: Satisfying the fatty acid demand of prostate cancer: Outlier overexpression of genes involved in de novo synthesis vs fatty acid uptake define two different and potentially synergistic prostate cancer phenotypes

Abstract Malignant transformation increases cellular demand for fatty acids (FA). Many cancers, including prostate cancer (PCa), show increased expression of fatty acid synthase (FASN), the enzyme that catalyzes the de novo synthesis of the FA palmitate. De novo FA synthesis is energetically expensive; in most normal cells FASN expression is low and de novo synthesis suppressed in favor of utilization of exogenous FA. In contrast, in cancer cells, de novo FA synthesis is an important source of precursors needed to support tumor growth. Much of the research effort on FA in cancer has focused on FASN and the other genes involved in de novo FA synthesis. However a number of observations suggest that alternate mechanisms for FA acquisition are also important, most notably studies showing that cancer cells can be rescued from the pro-apoptotic effect of FASN inhibition by exogenous palmitate. Using a biopsy-based approach designed to identify high risk prostate cancer phenotypes that are common in African American (AA) men, we identified a PCa subtype with outlier (&amp;gt; 10 fold) mRNA overexpression of fatty acid binding protein 5 (FABP5). FABP5 facilitates the utilization of palmitate and other FAs from outside the cell, and a FABP5 overexpression phenotype may confer a selective advantage when dietary FAs are abundant or when FASN is targeted as a therapy. The FABP5 outlier overexpression phenotype was observed in 7% Gleason sum (GS) 7-10 PCas. We also observed a second molecular subtype with outlier FASN overexpression in 9% of GS 7-10 PCas. With few exceptions these two PCa subtypes showed an “either-or” pattern with top quartile overexpression of FABP5 or FASN but not both (Spearman r = 0.385; P &amp;lt; 0.0001). Interestingly, in low grade (GS 6) PCas, median FABP5 mRNA overexpression is higher in AA than in European American (EA) men (P &amp;lt; 0.01) with GS6 PCas from AA men showing median FABP5 expression levels as high as that observed in GS 7-10 PCas. IHC confirmed variable expression of both FABP5 and FASN, including “patchwork” PCas with high Gleason pattern (GP) areas overexpressing FABP5 next to low GP areas overexpressing FASN. The net result may be a selective advantage for the high grade cancer if FABP5 allows it to exploit the FA being synthesized by the adjacent low grade focus. In a subset of PCas, FABP5 IHC showed robust nuclear staining consistent with its proposed role in regulating fatty acid mediated gene expression; the ratio of FABP5 nuclear/cytoplasmic staining was higher in PCa from AA than from EA patients (P &amp;lt; 0.05). Identification of a PCa subtype with high levels of FABP5 overexpression suggests a previously unrecognized mechanism by which some PCas can increase FA supply without de novo synthesis. Such a PCa subtype might be particularly sensitive to dietary interventions and relatively insensitive to FASN inhibitors. Citation Format: Sandra M. Gaston, James Kearns, George W. Adams, Soroush Rais-Bahrami, Jeffrey W. Nix, Peter N. Kolettis, James E. Bryant, Mark S. DeGuenther, Denise Oelschlager, Dennis Otali, William E. Grizzle. Satisfying the fatty acid demand of prostate cancer: Outlier overexpression of genes involved in de novo synthesis vs fatty acid uptake define two different and potentially synergistic prostate cancer phenotypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 457. doi:10.1158/1538-7445.AM2017-457

Cigarette smoke inhibits LPS-induced FABP5 expression by preventing c-Jun binding to the FABP5 promoter.

Cigarette smoking is the primary cause of chronic obstructive pulmonary disease (COPD) with repeated and sustained infections linked to disease pathogenesis and exacerbations. The airway epithelium constitutes the first line of host defense against infection and is known to be impaired in COPD. We have previously identified Fatty Acid Binding Protein 5 (FABP5) as an important anti-inflammatory player during respiratory infections and showed that overexpression of FABP5 in primary airway epithelial cells protects against bacterial infection and inflammation. While cigarette smoke down regulates FABP5 expression, its mechanism remains unknown. In this report, we have identified three putative c-Jun binding sites on the FABP5 promoter and show that cigarette smoke inhibits the binding of c-Jun to its consensus sequence and prevents LPS-induced FABP5 expression. Using chromatin immunoprecipitation, we have determined that c-Jun binds the FABP5 promoter when stimulated with LPS but the presence of cigarette smoke greatly reduces this binding. Furthermore, cigarette smoke or a mutation in the c-Jun binding site inhibits LPS-induced FABP5 promoter activity. These data demonstrate that cigarette smoke interferes with FABP5 expression in response to bacterial infection. Thus, functional activation of FABP5 may be a new therapeutic strategy when treating COPD patients suffering from exacerbations.

Satisfying the fatty acid demand of prostate cancer: De novo synthesis versus uptake as alternative and potentially cooperative prostate cancer phenotypes.

107 Background: Malignant transformation increases cellular demand for fatty acids (FA). Many cancers show increased expression of fatty acid synthase (FASN); FASN catalyzes the de novo synthesis of the FA palmitate. While research has focused on FASN and de novo tumor FA synthesis, observations suggest that alternate mechanisms for FA acquisition are also important, including studies showing that cancer cells can be rescued from FASN inhibition by exogenous palmitate. Using a biopsy-based approach, we identified a PrCa subtype with outlier (&gt;10 fold) overexpression of fatty acid binding protein 5 (FABP5). FABP5 facilitates the utilization of palmitate and other FAs from outside the cell; a FABP5 overexpression phenotype may confer a selective advantage when dietary FAs are abundant or when FASN is targeted as a therapy. Methods: 244 prostate biopsy patients were prospectively enrolled. Tissue prints were collected from each core for RNA and DNA preparation. mRNA was analyzed using Affymetrix arrays and TaqMan qrtPCR assays. Immunohistochemistry (IHC) was performed using archival radical prostatectomy (RP) specimens. Results: mRNA analyses revealed a PrCa subtype with &gt;10 x overexpression of FABP; this phenotype was observed in 7% of 268 cores with Gleason sum (GS) 7-10 PrCa. We also observed a second subtype with &gt;10 x overexpression of FASN in 9% of GS 7-10 cores. With few exceptions these two PrCa subtypes showed an “either-or” pattern with top-quartile overexpression of FABP5 or FASN but not both (Spearman r = - 0.385; P &lt; 0.0001). IHC confirmed variable expression, including “patchwork” PrCas with high Gleason pattern (GP) areas overexpressing FABP5 next to low GP areas overexpressing FASN. The net result may be a selective advantage for the high grade cancer if FABP5 allows it to exploit the FA being synthesized by the adjacent low grade focus Conclusions: Identification of a PrCa subtype with high levels of FABP5 overexpression suggests a previously unrecognized mechanism by which some PrCas can increase FA supply without de novo synthesis; such a PrCa subtype might be particularly sensitive to dietary interventions and relatively insensitive to FASN inhibitors.

Proteomic profiling reveals candidate markers for arsenic-induced skin keratosis

Proteomics technology is an attractive biomarker candidate discovery tool that can be applied to study large sets of biological molecules. To identify novel biomarkers and molecular targets in arsenic-induced skin lesions, we have determined the protein profile of arsenic-affected human epidermal stratum corneum by shotgun proteomics. Samples of palm and foot sole from healthy subjects were analyzed, demonstrating similar protein patterns in palm and sole. Samples were collected from the palms of subjects with arsenic keratosis (lesional and adjacent non-lesional samples) and arsenic-exposed subjects without lesions (normal). Samples from non-exposed healthy individuals served as controls. We found that three proteins in arsenic-exposed lesional epidermis were consistently distinguishably expressed from the unaffected epidermis. One of these proteins, the cadherin-like transmembrane glycoprotein, desmoglein 1 (DSG1) was suppressed. Down-regulation of DSG1 may lead to reduced cell-cell adhesion, resulting in abnormal epidermal differentiation. The expression of keratin 6c (KRT6C) and fatty acid binding protein 5 (FABP5) were significantly increased. FABP5 is an intracellular lipid chaperone that plays an essential role in fatty acid metabolism in human skin. This raises a possibility that overexpression of FABP5 may affect the proliferation or differentiation of keratinocytes by altering lipid metabolism. KRT6C is a constituent of the cytoskeleton that maintains epidermal integrity and cohesion. Abnormal expression of KRT6C may affect its structural role in the epidermis. Our findings suggest an important approach for future studies of arsenic-mediated toxicity and skin cancer, where certain proteins may represent useful biomarkers of early diagnoses in high-risk populations and hopefully new treatment targets. Further studies are required to understand the biological role of these markers in skin pathogenesis from arsenic exposure.

Abstract 20: Outlier overexpression of genes involved in fatty acid metabolism and processing define two aggressive prostate cancer phenotypes

Abstract Major shifts in fatty acid metabolism are part of the malignant phenotype of many types of cancer, including prostate cancer. We have used a biopsy based approach to characterize high grade prostate cancers in both African American and European American patients. This approach allows us to analyze prostate cancers from patients whose disease is too advanced for radical prostatectomy and who are thus not represented in the study specimens available from conventional biorepositories. mRNA gene expression profiling of high grade prostate cancers from biopsies revealed cancer subtypes with very high (&amp;gt;10 fold) levels of overexpression of fatty acid binding protein 5 (FABP5) and fatty acid synthase (FASN). Interestingly, these prostate cancer subtypes showed an either-or phenotype, with “super-overexpression” of either FABP5 or FASN but not both. These findings suggest two “outlier” prostate cancer subtypes with striking differences in the pathways that drive a shift in tumor fatty acid metabolism; one is a fatty acid synthase (FASN) dominant phenotype and the other a previously unrecognized fatty acid binding protein (FABP5) dominant phenotype. In contrast, prostate cancers with lower levels of FABP5 and/or FASN overexpression (2-4 fold) often co-overexpressed both of these genes. Immunohistochemical analyses confirmed prostate cancer FABP5 and FASN overexpression; both showed strong cytoplasmic staining. FABP5 also showed robust nuclear staining consistent with its proposed role in regulating fatty acid mediated gene expression. At both the mRNA and protein levels, the high grade prostate cancers with the highest levels of FABP5 over-expression were more common in African Americans, while the highest levels FASN overexpression were more common in prostate cancers from European Americans. These findings may provide the basis for more effective dietary interventions and targeted therapies for African American and European American patients with these two different subtypes of high grade prostate cancer. Citation Format: Sandra M. Gaston, Kerry Dehimer, James Kearns, Kyle-Ravi Chinsky, Dennis Otali, Denise Oelschlager, Soroush Rais-Bahrami, Jeffrey W. Nix, Peter Kolettis, George W. Adams, William E. Grizzle. Outlier overexpression of genes involved in fatty acid metabolism and processing define two aggressive prostate cancer phenotypes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 20.

The cancer-promoting gene fatty acid-binding protein 5 (FABP5) is epigenetically regulated during human prostate carcinogenesis.

FABPs (fatty-acid-binding proteins) are a family of low-molecular-mass intracellular lipid-binding proteins consisting of ten isoforms. FABPs are involved in binding and storing hydrophobic ligands such as long-chain fatty acids, as well as transporting these ligands to the appropriate compartments in the cell. FABP5 is overexpressed in multiple types of tumours. Furthermore, up-regulation of FABP5 is strongly associated with poor survival in triple-negative breast cancer. However, the mechanisms underlying the specific up-regulation of the FABP5 gene in these cancers remain poorly characterized. In the present study, we determined that FABP5 has a typical CpG island around its promoter region. The DNA methylation status of the CpG island in the FABP5 promoter of benign prostate cells (PNT2), prostate cancer cells (PC-3, DU-145, 22Rv1 and LNCaP) and human normal or tumour tissue was assessed by bisulfite sequencing analysis, and then confirmed by COBRA (combined bisulfite restriction analysis) and qAMP (quantitative analysis of DNA methylation using real-time PCR). These results demonstrated that overexpression of FABP5 in prostate cancer cells can be attributed to hypomethylation of the CpG island in its promoter region, along with up-regulation of the direct trans-acting factors Sp1 (specificity protein 1) and c-Myc. Together, these mechanisms result in the transcriptional activation of FABP5 expression during human prostate carcinogenesis. Importantly, silencing of Sp1, c-Myc or FABP5 expression led to a significant decrease in cell proliferation, indicating that up-regulation of FABP5 expression by Sp1 and c-Myc is critical for the proliferation of prostate cancer cells.

Cigarette Smoke Decreases Airway Epithelial FABP5 Expression and Promotes Pseudomonas aeruginosa Infection

Cigarette smoking is the primary cause of Chronic Obstructive Pulmonary Disease (COPD), which is characterized by chronic inflammation of the airways and destruction of lung parenchyma. Repeated and sustained bacterial infections are clearly linked to disease pathogenesis (e.g., exacerbations) and a huge burden on health care costs. The airway epithelium constitutes the first line of host defense against infection and our previous study indicated that Fatty Acid Binding Protein 5 (FABP5) is down regulated in airway epithelial cells of smokers with COPD as compared to smokers without COPD. We hypothesized that cigarette smoke (CS) exposure down regulates FABP5, thus, contributing to a more sustained inflammation in response to bacterial infection. In this report, we show that FABP5 is increased following bacterial infection but decreased following CS exposure of primary normal human bronchial epithelial (NHBE) cells. The goal of this study was to address FABP5 function by knocking down or overexpressing FABP5 in primary NHBE cells exposed to CS. Our data indicate that FABP5 down regulation results in increased P. aeruginosa bacterial load and inflammatory cytokine levels (e.g., IL-8) and decreased expression of the anti-bacterial peptide, β defensin-2. On the contrary, FABP5 overexpression exerts a protective function in airway epithelial cells against P. aeruginosa infection by limiting the production of IL-8 and increasing the expression of β defensin-2. Our study indicates that FABP5 exerts immunomodulatory functions in the airway epithelium against CS exposure and subsequent bacterial infection through its modulation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ activity. These findings support the development of FABP5/PPAR-γ-targeted therapeutic approach to prevent airway inflammation by restoring antimicrobial immunity during COPD exacerbations.

Fatty acid-binding protein 5 promotes cell proliferation and invasion in human intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a rare primary malignant liver tumor with an extremely poor prognosis. Recently its incidence has increased, however, little attention has been directed to factors related to its molecular carcinogenesis, including oncogenes, tumor suppressor genes and cell cycle-related proteins. ICC is generally characterized by strong proliferation, invasion and early metastasis. These biological behaviors of ICC, with respect to the genetic and molecular aspects, remain to be clarified. In this study, we performed a proteomic analysis to identify the proteomic alterations associated with carcinogenesis of ICC. Protein expression profiles of sixteen cases of ICC were compared with those of adjacent non-involved bile duct tissue. Among the 151 protein spots that showed a statistically significant expression difference (P<0.05), there were 50 spots with significantly increased intensity (3-fold increase) and 17 spots with decreased intensity (3-fold decrease) in cancerous tissues. Of these, increased expression of fatty acid-binding protein 5 (FABP5) was further confirmed by western blot analysis and immunohistochemical analysis. Immunohistochemical analysis of FABP5 expression in tumor specimens obtained from 43 patients with mass-forming (MF) type ICC showed a positive correlation of FABP5 immunoreactivity with tumor size (P=0.047), lymph node metastasis (P=0.013), angioinvasion (P=0.032) and staging (P=0.007). In addition, silencing FABP5 with short hairpin RNA (shRNA) suppressed cell proliferation and invasiveness in HuCCT1 cells, and conversely, overexpression of FABP5 in FABP5-negative Hep3B cells increased cell proliferation and invasiveness. Our study shows that FABP5 is significantly overexpressed in ICC combined lymph node metastasis and is involved in cell proliferation and invasion invitro. Our data suggest that FABP5 may be associated with tumor progression in ICC.

Fatty‐acid‐binding protein 5 promotes cell proliferation and invasion in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most malignant neoplasms worldwide, and the molecular mechanism of oral tumorigenesis is still unclear. Fatty-acid-binding protein 5 (FABP5) was found in our previous study to be upregulated in oral squamous cell carcinomas by proteomic analysis. The implications of FABP5 overexpression in oral cancer progression have not yet been elucidated. In this study, the recombinant adeno-associated virus vectors were used to deliver and increase the expression of FABP5 in human OSCC cell lines. U6 promoter-driven short-hairpin RNA (shRNA)-triggered RNA interference was used to block FABP5 gene expression. Transwell Matrigel invasion assay, MTS cell proliferation assay, reverse transcription-polymerase chain reaction, Western blot, and gelatin zymography analysis were used to investigate the effects of FABP5 on cell invasion, growth, and matrix metalloproteinase (MMP) production. Overexpression of FABP5 in oral cancer cells increased cell proliferation and invasiveness by increasing the expression of MMP-9. Silencing FABP5 with shRNA significantly suppressed cell proliferation, MMP-9 activities, and invasiveness. Our study provides the first evidence that FABP5 expression modulated MMP-9 production and the invasive behavior of oral cancer cells and suggests that FABP5 may provide novel targets for therapeutic intervention.