The fatty acid binding protein 7 (FABP7) is involved in proliferation and invasion of melanoma cells

Docosatrienoic Acid Inhibits Melanogenesis Partly through Suppressing the Intracellular MITF/Tyrosinase Axis

Melanogenesis, essential for skin photoprotection and pigmentation, can lead to disorders like melasma and hyperpigmentation, which are challenging to treat and affect quality of life. Docosatrienoic acid (DTA), a polyunsaturated omega-3 fatty acid, has been identified as a potential regulator of skin aging. This study investigates DTA's effects on melanogenesis and its underlying molecular mechanisms using in silico and in vitro analyses. SwissSimilarity analysis revealed that DTA shares close structural similarities with known anti-melanogenic lipids, suggesting it may inhibit melanogenesis in similar manners. Our results demonstrated that DTA reduces melanin content and intracellular tyrosinase activity in B16F10 cells, significantly downregulating the mRNA expression of tyrosinase, TRP-1, and TRP-2 by inhibiting MITF translocation to the nucleus. While DTA exhibited mild inhibitory effects on mushroom tyrosinase activity and antioxidant properties at higher concentrations, direct inhibition of tyrosinase is likely not the primary mechanism, as the observed anti-melanogenic effects occurred at much lower concentrations compared to those required for direct tyrosinase inhibition. Together, DTA-mediated modulation of MITF and tyrosinase mRNA expression offers a novel approach to treating hyperpigmentation. DTA's potential extends into the cosmetic industry, enhancing product stability, functionality, and aesthetics. Further research is needed to explore DTA's broader applications in skincare and cosmetic formulations.

The emerging role of fatty acid binding protein 7 (FABP7) in cancers

Fatty acid binding protein 7 (FABP7) is an intracellular protein involved in the uptake, transportation, metabolism, and storage of fatty acids (FAs). FABP7 is upregulated up to 20-fold in multiple cancers, usually correlated with poor prognosis. FABP7 silencing or pharmacological inhibition suggest FABP7 promotes cell growth, migration, invasion, colony and spheroid formation/increased size, lipid uptake, and lipid droplet formation. Xenograft studies show that suppression of FABP7 inhibits tumour formation and tumour growth, and improves host survival. The molecular mechanisms involve promotion of FA uptake, lipid droplets, signalling [focal adhesion kinase (FAK), proto-oncogene tyrosine-protein kinase Src (Src), mitogen-activated protein kinase kinase/p-extracellular signal-regulated kinase (MEK/ERK), and Wnt/β-catenin], hypoxia-inducible factor 1-alpha (Hif1α), vascular endothelial growth factor A/prolyl 4-hydroxylase subunit alpha-1 (VEGFA/P4HA1), snail family zinc finger 1 (Snail1), and twist-related protein 1 (Twist1). The oncogenic capacity of FABP7 makes it a promising pharmacological target for future cancer treatments.

CA9, CYFIP2 and LGALS3BP-A Novel Biomarker Panel to Aid Prognostication in Glioma

Brain cancer is a devastating and life-changing disease. Biomarkers are becoming increasingly important in addressing clinical issues, including in monitoring tumour progression and assessing survival and treatment response. The goal of this study was to identify prognostic biomarkers associated with glioma progression. Discovery proteomic analysis was performed on a small cohort of astrocytomas that were diagnosed as low-grade and recurred at a higher grade. Six proteins were chosen to be validated further in a larger cohort. Three proteins, CA9, CYFIP2, and LGALS3BP, were found to be associated with glioma progression and, in univariate analysis, could be used as prognostic markers. However, according to the results of multivariate analysis, these did not remain significant. These three proteins were then combined into a three-protein panel. This panel had a specificity and sensitivity of 0.7459 for distinguishing between long and short survival. In silico data confirmed the prognostic significance of this panel.

The Role of Methylation in Chronic Lymphocytic Leukemia and Its Prognostic and Therapeutic Impacts in the Disease: A Systematic Review

Epigenetic regulation has been thoroughly investigated in recent years and has emerged as an important aspect of chronic lymphocytic leukemia (CLL) biology. Characteristic aberrant features such as methylation patterns and global DNA hypomethylation were the early findings of the research during the last decades. The investigation in this field led to the identification of a large number of genes where methylation features correlated with important clinical and laboratory parameters. Gene-specific analyses investigated methylation in the gene body enhancer regions as well as promoter regions. The findings included genes and proteins involved in key pathways that play central roles in the pathophysiology of the disease. Τhe application of these findings beyond the theoretical understanding can not only lead to the creation of prognostic and predictive models and scores but also to the design of novel therapeutic agents. The following is a review focusing on the present knowledge about single gene/gene promoter methylation or mRNA expression in CLL cases as well as records of older data that have been published in past papers.

The Multifunctional Family of Mammalian Fatty Acid-Binding Proteins

Fatty acid-binding proteins (FABPs) are small lipid-binding proteins abundantly expressed in tissues that are highly active in fatty acid (FA) metabolism. Ten mammalian FABPs have been identified, with tissue-specific expression patterns and highly conserved tertiary structures. FABPs were initially studied as intracellular FA transport proteins. Further investigation has demonstrated their participation in lipid metabolism, both directly and via regulation of gene expression, and in signaling within their cells of expression. There is also evidence that they may be secreted and have functional impact via the circulation. It has also been shown that the FABP ligand binding repertoire extends beyond long-chain FAs and that their functional properties also involve participation in systemic metabolism. This article reviews the present understanding of FABP functions and their apparent roles in disease, particularly metabolic and inflammation-related disorders and cancers.

Spatial Transcriptomics Identifies Expression Signatures Specific to Lacrimal Gland Adenoid Cystic Carcinoma Cells

Although primary tumors of the lacrimal gland are rare, adenoid cystic carcinoma (ACC) is the most common and lethal epithelial lacrimal gland malignancy. Traditional management of lacrimal gland adenoid cystic carcinoma (LGACC) involves the removal of the eye and surrounding socket contents, followed by chemoradiation. Even with this radical treatment, the 10-year survival rate for LGACC is 20% given the propensity for recurrence and metastasis. Due to the rarity of LGACC, its pathobiology is not well-understood, leading to difficulties in diagnosis, treatment, and effective management. Here, we integrate bulk RNA sequencing (RNA-seq) and spatial transcriptomics to identify a specific LGACC gene signature that can inform novel targeted therapies. Of the 3499 differentially expressed genes identified by bulk RNA-seq, the results of our spatial transcriptomic analysis reveal 15 upregulated and 12 downregulated genes that specifically arise from LGACC cells, whereas fibroblasts, reactive fibrotic tissue, and nervous and skeletal muscle account for the remaining bulk RNA-seq signature. In light of the analysis, we identified a transitional state cell or stem cell cluster. The results of the pathway analysis identified the upregulation of PI3K-Akt signaling, IL-17 signaling, and multiple other cancer pathways. This study provides insights into the molecular and cellular landscape of LGACC, which can inform new, targeted therapies to improve patient outcomes.

Understanding FABP7 binding to fatty acid micelles and membranes

Fatty acid-binding proteins (FABPs) are chaperones that facilitate the transport of long-chain fatty acids within the cell and can provide cargo-dependent localization to specific cellular compartments. Understanding the nature of this transport is important because lipid signaling functions are associated with metabolic pathways impacting disease pathologies including cancer, autism, and schizophrenia. FABPs often associate with cell membranes to acquire and deliver their bound cargo as part of transport. We focus on brain FABP (FABP7), which demonstrates localization to the cytoplasm and nucleus, influencing transcription and fatty acid metabolism. We use a combined biophysical-computational approach to elucidate the interaction between FABP7 and model membranes. Specifically, we use multiple experiments to demonstrate that FABP7 can bind oleic acid and docosahexaenoic acid micelles. Data from NMR and multiscale molecular dynamics simulations reveal that the interaction with micelles is through FABP7's portal region residues. Simulations suggest that binding to membranes occurs through the same residues as micelles. Simulations also capture binding events where fatty acids dissociate from the membrane and enter FABP7's binding pocket. Overall, our data shed light on the interactions between FABP7 and OA or DHA micelles and provide insight into the transport of long-chain fatty acids.

FABP7 inhibits proliferation and invasion abilities of cutaneous squamous cell carcinoma cells via the Notch signaling pathway

Cutaneous squamous cell carcinoma (CSCC) is one of the most common non-melanoma skin cancers worldwide. Fatty acid-binding protein 7 (FABP7) has been reported to be involved in the occurrence, development, metastasis and prognosis of various tumors. In addition, downregulated FABP7 expression was demonstrated in cutaneous malignant melanoma in a previous study. Therefore, we speculated that FABP7 may be a biomarker for CSCC diagnosis. The aim of the present study was to determine the molecular mechanism underlying the effects of FABP7 in CSCC, which may provide a new diagnostic biomarker or treatment target for CSCC. Reverse transcription-PCR, western blotting and immunohistochemistry assays were performed to detect the expression levels of FABP7 in CSCC tissues and cells. Overexpression of FABP7 was achieved in A431 and colo-16 cell lines by transfection with an overexpression vector (oeFABP7). Cell proliferation, colony formation, migration and invasion were detected by Cell Counting Kit-8, crystal violet, scratch and Transwell assays, respectively. Following FABP7 overexpression, western blotting was used to determine the expression levels of proliferation-, invasion- and Notch pathway-associated proteins, including Snail, N-cadherin, Twist, matrix metalloproteinase (MMP)-2, MMP-7, Notch 1 and Notch 3. In addition a CSCC model in nude mice was constructed. Immunohistochemistry was used to determine the expression levels of FABP7, Ki67, Notch 1 and Notch 3. It was demonstrated that FABP7 expression levels were significantly reduced in human CSCC tissues and cells compared with normal samples. Overexpression of FABP7 inhibited the proliferation, invasion and migration abilities of A431 and colo-16 cells compared with those in the negative control group. In addition, transfection with oeFABP7 reduced the expression levels of proliferation-, invasion- and Notch pathway-associated proteins compared with those in the negative control group. Overexpression of FABP7 also reduced the growth of CSCC tumors in vivo and inhibited the expression of Ki67, Notch 1 and Notch 3. Therefore, the results of the present study suggested that FABP7 may inhibit the proliferation and invasion of CSCC cells via the Notch signaling pathway.

Cytoplasmic fatty acid-binding proteins in metabolic diseases and cancers

Cytoplasmic fatty acid-binding proteins (FABPs) are multipurpose proteins that can modulate lipid fluxes, trafficking, signaling, and metabolism. FABPs regulate metabolic and inflammatory pathways, its inhibition can improve type 2 diabetes mellitus and atherosclerosis. In addition, FABPs are involved in obesity, metabolic disease, cardiac dysfunction, and cancers. FABPs are promising tissue biomarkers in solid tumors for diagnostic and/or prognostic targets for novel therapeutic strategies. The signaling responsive elements of FABPs and determinants of FABP-mediated functions may be exploited in preventing or treating these diseases.

Metastatic Tumor Cell-Specific FABP7 Promotes NSCLC Metastasis via Inhibiting β-Catenin Degradation

Metastasis accounts for 90% of cancer-related deaths and represents a prominent malignant feature in non-small cell lung cancer (NSCLC), while tumor cell-specific mechanisms and molecules pivotal for the metastatic capacity remain unclear. By analyzing single-cell RNA sequencing data, we found that fatty acid binding protein 7 (FABP7) was specifically up-regulated in tumor cells of metastatic NSCLC patients and might be a prognostic indicator for poor survival. Experimental studies based on NSCLC cell lines showed that FABP7 promoted the metastatic competencies of NSCLC cells in vitro and in vivo. Mechanistically, we demonstrated that FABP7 was important to canonical Wnt signaling activation and competitively inhibited the interaction between β-catenin and components of its cytoplasmic degradation complex, thereby repressing the phosphorylation-dependent ubiquitination and degradation of β-catenin. Our present study identifies FABP7 as a metastatic tumor cell-specific pro-metastatic gene and uncovers a previously unknown regulatory mechanism underlying Wnt hyperactivation via FABP7-impaired cytoplasmic β-catenin degradation, implicating a novel molecule in regulating NSCLC metastasis.

PPARα Agonist Fenofibrate Enhances Cancer Vaccine Efficacy

Reducing metabolic stress within the tumor microenvironment (TME) could be essential for improving the efficacy of cancer immunotherapy. Using a mouse model of melanoma, we show here that appropriately timed treatment with the PPARα agonist fenofibrate improves the ability of a T cell-inducing cancer vaccine to delay tumor progression. Fenofibrate reduced the use of glucose by tumor and stromal cells in the TME and promoted the use of fatty acids for their metabolic needs. The glucose within the TME was in turn available for use by vaccine-induced tumor-infiltrating CD8⁺ T cells, which improved their ability to slow tumor progression. Early fenofibrate treatment 3 days after vaccination improved functions of circulating CD8⁺ T cells but failed to significantly affect tumor-infiltrating lymphocyte (TIL) metabolism or decrease tumor progression. In contrast, delaying treatment until day 5 after vaccination modified TIL metabolism and augmented the vaccine's ability to slow tumor progression. In summary, our findings reveal that a PPARα agonist can increase the efficacy of a cancer vaccine by reprogramming cells within tumors to increase fatty acid metabolism, providing T cells access to glucose in the TME. SIGNIFICANCE: These findings suggest that metabolic manipulations using already approved drugs may offer an easy pathway to increase the efficacy of vaccines against solid tumors.

BLBP Is Both a Marker for Poor Prognosis and a Potential Therapeutic Target in Paediatric Ependymoma

Paediatric ependymomas are aggressive, treatment-resistant tumours with a tendency towards relapse, consistent with a sub-population of therapy-resistant cancer stem cells. These cells are believed to derive from brain lipid binding protein (BLBP)-expressing radial glia, hence we proposed that BLBP may be a marker for ependymoma therapy resistance. BLBP protein expression correlated with reduced overall survival (OS) in patients from two trials (CNS9204, a chemotherapy-led infant trial-5 y OS 45% vs. 80%, p = 0.011-and CNS9904, a radiotherapy-led trial-OS 38% vs. 85%, p = 0.002). All ependymoma cell lines examined by qRT-PCR expressed BLBP, with expression elevated in stem cell-enriched neurospheres. Modulation of BLBP function in 2D and 3D assays, using either peroxisome proliferator activated receptor (PPAR) antagonists or BLBP's fatty acid substrate docosahexaneoic acid (DHA), potentiated chemotherapy response and reduced cell migration and invasion in ependymoma cell lines. BLBP is therefore an independent predictor of poor survival in paediatric ependymoma, and treatment with PPAR antagonists or DHA may represent effective novel therapies, preventing chemotherapy resistance and invasion in paediatric ependymoma patients.

Ligand Bound Fatty Acid Binding Protein 7 (FABP7) Drives Melanoma Cell Proliferation Via Modulation of Wnt/β-Catenin Signaling

PURPOSE

Fatty acid-binding protein 7 (FABP7) involved in intracellular lipid dynamics, is highly expressed in melanomas and associated with decreased patient survival. Several studies put FABP7 at the center of melanoma cell proliferation. However, the underlying mechanisms are not well deciphered. This study examines the effects of FABP7 on Wnt/β-catenin signaling that enhances proliferation in melanoma cells.

METHODS

Skmel23 cells with FABP7 silencing and Mel2 cells overexpressed with wild-type FABP7 (FABP7wt) and mutated FABP7 (FABP7mut) were used. Cell proliferation and migration were analyzed by proliferation and wound-healing assay, respectively. Transcriptional activation of the Wnt/β-catenin signaling was measured by luciferase reporter assay. The effects of a specific FABP7 inhibitor, MF6, on proliferation, migration, and modulation of the Wnt/β-catenin signaling were examined.

RESULTS

FABP7 siRNA knockdown in Skmel23 decreased proliferation and migration, cyclin D1 expression, as well as Wnt/β-catenin activity. Similarly, FABP7wt overexpression in Mel2 cells increased these effects, but FABP7mut abrogated these effects. Pharmacological inhibition of FABP7 function with MF6 suppressed FABP7-regulated proliferation of melanoma cells.

CONCLUSION

These results suggest the importance of the interaction between FABP7 and its ligands in melanoma proliferation modulation, and the beneficial implications of therapeutic targeting of FABP7 for melanoma treatment.

Global gene methylation profiling of common warts caused by human papillomaviruses infection

Infection with the human papillomaviruses (HPV) often involves the epigenetic modification of the host genome. Despite its prevalence among the population, host genome methylation in HPV-induced warts is not clearly understood. In this study, genome-wide methylation profiling was carried out on paired healthy skin and wart samples in order to investigate the effects that benign HPV infection has on gene methylation status. To overcome this gap in knowledge, paired wart (n = 12) and normal skin (n = 12) samples were obtained from Arab males in order to perform DNA extraction and subsequent genome-wide methylation profiling on the Infinium Methylation EPIC Bead Chip microarray. Analysis of differential methylation revealed a clear pattern of discrimination between the wart and normal skin samples. In warts, the most differentially methylated (DM) genes included long non-coding RNAs (AC005884, AL049646.2, AC126121.2, AP001790.1, and AC107959.3), microRNAs (MIR374B, MIR596, MIR1255B1, MIR26B, and MIR196A2),snoRNAs (SNORD114-22, SNORD70, and SNORD114-31), pseudogenes (AC069366.1, RNU4ATAC11P, AC120057.1, NANOGP3, AC106038.2, TPT1P2, SDC4P, PKMP3, and VN2R3P), and protein-coding genes (AREG, GJB2, C12orf71, AC020909.2, S100A8, ZBED2, FABP7, and CYSLTR1). In addition, pathway analysis revealed that, among the most differentially methylated genes, STAT5A, RARA, MEF2D, MAP3K8, and THRA were the common regulators. It can be observed that HPV-induced warts involve a clear and unique epigenetic alteration to the host genome.

Integration and Comparison of Transcriptomic and Proteomic Data for Meningioma

Meningioma are the most frequent primary intracranial tumour. Management of aggressive meningioma is complex, and development of effective biomarkers or pharmacological interventions is hampered by an incomplete knowledge of molecular landscape. Here, we present an integrated analysis of two complementary omics studies to investigate alterations in the "transcriptome-proteome" profile of high-grade (III) compared to low-grade (I) meningiomas. We identified 3598 common transcripts/proteins and revealed concordant up- and downregulation in grade III vs. grade I meningiomas. Concordantly upregulated genes included FABP7, a fatty acid binding protein and the monoamine oxidase MAOB, the latter of which we validated at the protein level and established an association with Food and Drug Administration (FDA)-approved drugs. Notably, we derived a plasma signature of 21 discordantly expressed genes showing positive changes in protein but negative in transcript levels of high-grade meningiomas, including the validated genes CST3, LAMP2, PACS1 and HTRA1, suggesting the acquisition of these proteins by tumour from plasma. Aggressive meningiomas were enriched in processes such as oxidative phosphorylation and RNA metabolism, whilst concordantly downregulated genes were related to reduced cellular adhesion. Overall, our study provides the first transcriptome-proteome characterisation of meningioma, identifying several novel and previously described transcripts/proteins with potential grade III biomarker and therapeutic significance.

Lipid metabolic Reprogramming: Role in Melanoma Progression and Therapeutic Perspectives

Simple Summary

Melanoma is a devastating skin cancer characterized by an impressive metabolic plasticity. Melanoma cells are able to adapt to the tumor microenvironment by using a variety of fuels that contribute to tumor growth and progression. In this review, the authors summarize the contribution of the lipid metabolic network in melanoma plasticity and aggressiveness, with a particular attention to specific lipid classes such as glycerophospholipids, sphingolipids, sterols and eicosanoids. They also highlight the role of adipose tissue in tumor progression as well as the potential antitumor role of drugs targeting critical steps of lipid metabolic pathways in the context of melanoma.

Abstract

Metabolic reprogramming contributes to the pathogenesis and heterogeneity of melanoma. It is driven both by oncogenic events and the constraints imposed by a nutrient- and oxygen-scarce microenvironment. Among the most prominent metabolic reprogramming features is an increased rate of lipid synthesis. Lipids serve as a source of energy and form the structural foundation of all membranes, but have also emerged as mediators that not only impact classical oncogenic signaling pathways, but also contribute to melanoma progression. Various alterations in fatty acid metabolism have been reported and can contribute to melanoma cell aggressiveness. Elevated expression of the key lipogenic fatty acid synthase is associated with tumor cell invasion and poor prognosis. Fatty acid uptake from the surrounding microenvironment, fatty acid β-oxidation and storage also appear to play an essential role in tumor cell migration. The aim of this review is (i) to focus on the major alterations affecting lipid storage organelles and lipid metabolism. A particular attention has been paid to glycerophospholipids, sphingolipids, sterols and eicosanoids, (ii) to discuss how these metabolic dysregulations contribute to the phenotype plasticity of melanoma cells and/or melanoma aggressiveness, and (iii) to highlight therapeutic approaches targeting lipid metabolism that could be applicable for melanoma treatment.

Using whole-exome sequencing and protein interaction networks to prioritize candidate genes for germline cutaneous melanoma susceptibility

Although next-generation sequencing has demonstrated great potential for novel gene discovery, confirming disease-causing genes after initial discovery remains challenging. Here, we applied a network analysis approach to prioritize candidate genes identified from whole-exome sequencing analysis of 98 cutaneous melanoma patients from 27 families. Using a network propagation method, we ranked candidate genes by their similarity to known disease genes in protein-protein interaction networks and identified gene clusters with functional connectivity. Using this approach, we identified several new candidate susceptibility genes that warrant future investigations such as NGLY1, IL1RN, FABP2, PRKDC, and PROSER2. The propagated network analysis also allowed us to link families that did not have common underlying genes but that carried variants in genes that interact on protein-protein interaction networks. In conclusion, our study provided an analysis perspective for gene prioritization in the context of genetic heterogeneity across families and prioritized top potential candidate susceptibility genes in our dataset.

Interactome Analysis of the Differentially Expressed Proteins in Uterine Leiomyoma

BACKGROUND

Recent advances in proteomics present enormous opportunities to discover proteome related disparities and thus understanding the molecular mechanisms related to a disease. Uterine leiomyoma is a benign monoclonal tumor, located in the pelvic region, and affecting 40% of reproductive aged female.

OBJECTIVE

Identification and characterization of the differentially expressed proteins associated with leiomyogenesis by comparing uterine leiomyoma and normal myometrium.

METHODS

Paired samples of uterine leiomyoma and adjacent myometrium retrieved from twenty-five females suffering from uterine leiomyoma (n=50) were submitted to two-dimensional electrophoresis (2-DE), matrixassisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and to reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Comparison of protein patterns revealed seven proteins with concordantly increased spot intensities in leiomyoma samples. E3 ubiquitin-protein ligase MIB2 (MIB2), Mediator of RNA polymerase II transcription subunit 10 (MED10), HIRA-interacting protein (HIRP3) and Fatty acid binding protein brain (FABP7) were found to be upregulated. While, Biogenesis of lysosome-related organelles complex 1 subunit 2 (BL1S2), Shadow of prion protein (SPRN) and RNA binding motif protein X linked like 2 (RMXL2) were found to be exclusively present in leiomyoma sample. The expression modulations of the corresponding genes were further validated which corroborated with the 2-DE result showing significant upregulation in leiomyoma. We have generated a master network showing the interactions of the experimentally identified proteins with their close neighbors and further scrutinized the network to prioritize the routes leading to cell proliferation and tumorigenesis.

CONCLUSION

This study highlights the importance of identified proteins as potential targets for therapeutic purpose. This work provides an insight into the mechanism underlying the overexpression of the proteins but warrants further investigations.

FABP7 is a key metabolic regulator in HER2+ breast cancer brain metastasis

Overexpression of human epidermal growth factor receptor 2 (HER2) in breast cancer patients is associated with increased incidence of breast cancer brain metastases (BCBM), but the mechanisms underlying this phenomenon remain unclear. Here, to identify brain-predominant genes critical for the establishment of BCBM, we conducted an in silico screening analysis and identified that increased levels of fatty acid-binding protein 7 (FABP7) correlate with a lower survival and higher incidence of brain metastases in breast cancer patients. We validated these findings using HER2+ BCBM cells compared with parental breast cancer cells. Importantly, through knockdown and overexpression assays, we characterized the role of FABP7 in the BCBM process in vitro and in vivo. Our results uncover a key role of FABP7 in metabolic reprogramming of HER2 + breast cancer cells, supporting a glycolytic phenotype and storage of lipid droplets that enable their adaptation and survival in the brain microenvironment. In addition, FABP7 is shown to be required for upregulation of key metastatic genes and pathways, such as integrins-Src and VEGFA, and for the growth of HER2+ breast cancer cells in the brain microenvironment in vivo. Together, our results support FABP7 as a potential target for the treatment of HER2+ BCBM.

Role of fatty acid binding proteins (FABPs) in cancer development and progression

Fatty acid binding proteins (FABPs) are small, water soluble proteins that bind long chain fatty acids and other biologically active ligands to facilitate intracellular localization. Twelve FABP family members have been identified to date, with 10 isoforms expressed in humans. Functionally, FABPs are important in fatty acid metabolism and transport, with distinct family members having the capacity to influence gene transcription. Expression of FABPs is usually cell/tissue specific to one predominant FABP family member. Dysregulation of FABP expression can occur through genetic mutation and/or environmental-lifestyle influences. In addition to intracellular function, exogenous, circulating FABP expression can occur and is associated with specific disease states such as insulin resistance. A role for FABPs is increasingly being reported in tumor biology with elevated exogenous FABP expression being associated with tumor progression and invasiveness. However, a less clear role has been appreciated for dysregulated FABP expression during cell transformation and early expansion.

Role of FABP7 in tumor cell signaling

Lipids are major molecules for the function of organisms and are involved in the pathophysiology of various diseases. Fatty acids (FAs) signaling and their metabolism are some of the most important pathways in tumor development, as lipids serve as energetic sources during carcinogenesis. Fatty acid binding proteins (FABPs) facilitate FAs transport to different cell organelles, modulating their metabolism along with mediating other physiological activities. FABP7, brain-typed FABP, is thought to be an important molecule for cell proliferation in healthy as well as diseased organisms. Several studies on human tumors and tumor-derived cell lines put FABP7 in the center of tumorigenesis, and its high expression level has been reported to correlate with poor prognosis in different tumor types. Several types of FABP7-expressing tumors have shown an up-regulation of cell signaling activity, but molecular mechanisms of FABP7 involvement in tumorigenesis still remain elusive. In this review, we focus on the expression and function of FABP7 in different tumors, and possible mechanisms of FABP7 in tumor proliferation and migration.

The myelin protein PMP2 is regulated by SOX10 and drives melanoma cell invasion

The transcription factor sex determining region Y-box 10 (SOX10) plays a key role in the development of melanocytes and glial cells from neural crest precursors. SOX10 is involved in melanoma initiation, proliferation, invasion, and survival. However, specific mediators which impart its oncogenic properties remain widely unknown. To identify target genes of SOX10, we performed RNA sequencing after ectopic expression of SOX10 in human melanoma cells. Among nine differentially regulated genes, peripheral myelin protein 2 (PMP2) was consistently upregulated in several cell lines. Direct regulation of PMP2 by SOX10 was shown by chromatin immunoprecipitation, electrophoretic mobility shift, and luciferase reporter assays. Moreover, a coregulation of PMP2 by SOX10 and early growth response 2 in melanoma cells was found. Phenotypical investigation demonstrated that PMP2 expression can increase melanoma cell invasion. As PMP2 protein was detected only in a subset of melanoma cell lines, it might contribute to melanoma heterogeneity.

Down-regulation of A-FABP predicts non-muscle invasive bladder cancer progression: investigation with a long term clinical follow-up

BACKGROUND

Non-muscle invasive bladder cancers (NMIBC: pTa, pT1) are characterised by a high risk of recurrence and/or progression. Identification of prognostic markers is needed to improve both diagnosis and management of the disease. The aim of this study was to analyse the expression of A-FABP (adipocyte-fatty acid binding protein) and to evaluate its prognostic value in bladder cancer with a long term clinical follow-up.

METHODS

A-FABP expression was investigated by immunohistochemistry in 236 tumours (114 pTa, 61 pT1, 61 pT2-4). Immunostaining was classified as negative (absent or weak immunostaining and moderate or strong staining on ≤10% of cells) or positive (moderate or strong staining on > 10% of cells). Event-free survival (EFS) and overall survival (OS) were determined with a 87.3 months median follow-up in the overall cohort. Recurrence-free survival (RFS) and progression-free survival (PFS) were established in NMIBC.

RESULTS

Loss of A-FABP was associated with higher mean age, high stage/grade, and the presence of metastatic lymph nodes. It was correlated with shorter median EFS (17.5 vs 62.5 months; p = 0.001) and mean OS (76.7 vs 154.2 months; p = 0.009) and with higher risk of progression in the pTa/pT1 subgroup (HR, 0.36; 95% CI, 0.13-0.96; p = 0.041) and importantly in the pTa tumours (HR, 0.34; 95% CI, 0.10-0.97; p = 0.045).

CONCLUSION

These results demonstrated that loss of A-FABP expression following a long follow-up was predictive of pTa and pTa/pT1 progression. Immunohistochemistry on diagnostic biopsy is easy to use and could be of value to help clinicians to propose appropriate treatment for these tumours.

Stress and interferon signalling-mediated apoptosis contributes to pleiotropic anticancer responses induced by targeting NGLY1

Background

Although NGLY1 is known as a pivotal enzyme that catalyses the deglycosylation of denatured glycoproteins, information regarding the responses of human cancer and normal cells to NGLY1 suppression is limited.

Methods

We examined how NGLY1 expression affects viability, tumour growth, and responses to therapeutic agents in melanoma cells and an animal model. Molecular mechanisms contributing to NGLY1 suppression-induced anticancer responses were revealed by systems biology and chemical biology studies. Using computational and medicinal chemistry-assisted approaches, we established novel NGLY1-inhibitory small molecules.

Results

Compared with normal cells, NGLY1 was upregulated in melanoma cell lines and patient tumours. NGLY1 knockdown caused melanoma cell death and tumour growth retardation. Targeting NGLY1 induced pleiotropic responses, predominantly stress signalling-associated apoptosis and cytokine surges, which synergise with the anti-melanoma activity of chemotherapy and targeted therapy agents. Pharmacological and molecular biology tools that inactivate NGLY1 elicited highly similar responses in melanoma cells. Unlike normal cells, melanoma cells presented distinct responses and high vulnerability to NGLY1 suppression.

Conclusion

Our work demonstrated the significance of NGLY1 in melanoma cells, provided mechanistic insights into how NGLY1 inactivation leads to eradication of melanoma with limited impact on normal cells, and suggested that targeting NGLY1 represents a novel anti-melanoma strategy.

FABP7 promotes cell proliferation and survival in colon cancer through MEK/ERK signaling pathway

Colon cancer (CC), one of the most frequently diagnosed malignancies deriving from the digestive system, has greatly threatened human health and life. Fatty acid binding protein 7 (FABP7), an intracellular protein with the tissue-specific expression pattern, has been reported to be implicated in diverse types of human tumors. However, the biological role of FABP7 in CC is still poorly understood. The current study aimed to investigate the role of FABP7 in CC and illuminate the potential molecular mechanisms. In this present study, we found that FABP7 was highly expressed in CC tissues and cell lines, suggesting the possible involvement of FABP7 in CC tumorigenesis. Moreover, functional investigations showed that FABP7-overexpression promoted CC cell proliferation, colony formation, cell cycle progression and inhibited cell apoptosis; on the contrary, FABP7 knockdown produced an inhibitory effects on CC cell proliferation and survival. Notably, FABP7 knockdown inhibited colon tumor growth in vivo. In addition, mechanistic investigations demonstrated that FABP7 exerted its promoting effects on CC cell proliferation and survival through activation of the MEK/ERK signaling pathway. Collectively, our data indicate that FABP7 may be used as a novel diagnostic bio-marker and a potential therapeutic target for CC.

Diverse roles of fatty acid binding proteins (FABPs) in development and pathogenesis of cancers

One of the most importantly involved pathways in cancer development is fatty-acid signaling pathway. Synthesized lipids as energetic sources are consumed by cancer cells for proliferation, growth, survival, invasion and angiogenesis. Fatty acids as signaling compounds regulate metabolic and transcriptional networks, survival pathways and inflammatory responses. Aggregation of fatty acids with fatty acid binding proteins (FABPs) facilitates their transportation to different cell organelles. FABPs, a group of lipid binding proteins modulate fatty acid metabolism, cell growth and proliferation and cancer development. They may be used as tumor marker in some cancers. FABPs are expressed in most malignancies such as prostate, breast, liver, bladder and lung cancer which are associated with the incidence, proliferation, metastasis, invasion of tumors. This review introduces several isoforms of FABPs (FABP1-12) and summarizes their function and their possible roles in cancer development through some proposed mechanisms.

The increased expression of fatty acid-binding protein 9 in prostate cancer and its prognostic significance

In contrast to numerous studies conducted to investigate the crucial role of fatty acid binding protein 5 (FABP5) in prostate cancer, investigations on the possible involvement of other FABPs are rare. Here we first measured the mRNA levels of 10 FABPs in benign and malignant prostate cell lines and identified the differentially expressed FABP6 and FABP9 mRNAs whose levels in all malignant cell lines were higher than those in the benign cells. Thereafter we assessed the expression status of FABP6 and FABP9 in both prostate cell lines and in human tissues. FABP6 protein was overexpressed only in 1 of the 5 malignant cell lines and its immunostaining intensities were not significantly different between benign and malignant prostate tissues. In contrast, FABP9 protein was highly expressed in highly malignant cell lines PC-3 and PC3-M, but its level in the benign PNT-2 and other malignant cell lines was not detectable. When analysed in an archival set of human prostate tissues, immunohistochemical staining intensity for FABP9 was significantly higher in carcinomas than in benign cases and the increase in FABP9 was significantly correlated with reduced patient survival times. Moreover, the increased level of staining for FABP9 was significantly associated with the increased joint Gleason scores (GS) and androgen receptor index (AR). Suppression of FABP9 expression in highly malignant PC3-M cells inhibited their invasive potential. Our results suggest that FABP9 is a valuable prognostic marker to predict the outcomes of prostate cancer patients, perhaps by playing an important role in prostate cancer cell invasion.

Metabolic strategies of melanoma cells: Mechanisms, interactions with the tumor microenvironment, and therapeutic implications

Melanomas are metabolically heterogeneous, and they are able to adapt in order to utilize a variety of fuels that facilitate tumor progression and metastasis. The significance of metabolism in melanoma is supported by growing evidence of impact on the efficacy of contemporary therapies for this disease. There are also data to support that the metabolic phenotypes of melanoma cells depend upon contributions from both intrinsic oncogenic pathways and extrinsic factors in the tumor microenvironment. This review summarizes current understanding of the metabolic processes that promote cutaneous melanoma tumorigenesis and progression, the regulation of cancer cell metabolism by the tumor microenvironment, and the impact of metabolic pathways on targeted and immune therapies.

Functional analysis of fatty acid binding protein 7 and its effect on fatty acid of renal cell carcinoma cell lines

Background

Renal cell carcinomas (RCCs) overexpress fatty acid binding protein 7 (FABP7). We chose to study the TUHR14TKB cell line, because it expresses higher levels of FABP7 than other cell lines derived from renal carcinomas (OS-RC-2, 786-O, 769-P, Caki-1, and ACHN).

Methods

FABP7 expression was detected using western blotting and real-time PCR. Cell proliferation was determined using an MTS assay and by directly by counting cells. The cell cycle was assayed using flow cytometry. Cell migration was assayed using wound-healing assays. An FABP7 expression vector was used to transfect RCC cell lines.

Results

The levels of FABP7 expressed by TUHR14TKB cells and their doubling times decreased during passage. High-passage TUHR14TKB cells comprised fewer G0/G1-phase and more S-phase cells than low-passage cells. Cell proliferation differed among subclones isolated from cultures of low-passage TUHR14TKB cells. The proliferation of TUHR14TKB cells decreased when FABP7 was overexpressed, and the cell migration property of TUHR14TKB cells were decreased when FABP7 was overexpressed. High concentrations of docosatetraenoic acid and eicosapentaenoic acid accumulated in TUHR14TKB cells that overexpressed FABP7, and docosatetraenoic acid enhanced cell proliferation.

Conclusions

The TUHR14TKB cell line represents a heterogeneous population that does not express FABP7 when it rapidly proliferates. The differences in FABP7 function between RCC cell lines suggests that FABP7 affects cell proliferation depending on cell phenotype.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3184-x) contains supplementary material, which is available to authorized users.

Fatty acid-binding protein 7 regulates function of caveolae in astrocytes through expression of caveolin-1

Fatty acid-binding proteins (FABPs) bind and solubilize long-chain fatty acids, controlling intracellular lipid dynamics. FABP7 is expressed by astrocytes in the developing brain, and suggested to be involved in the control of astrocyte lipid homeostasis. In this study, we sought to examine the role of FABP7 in astrocytes, focusing on plasma membrane lipid raft function, which is important for receptor-mediated signal transduction in response to extracellular stimuli. In FABP7-knockout (KO) astrocytes, the ligand-dependent accumulation of Toll-like receptor 4 (TLR4) and glial cell-line-derived neurotrophic factor receptor alpha 1 into lipid raft was decreased, and the activation of mitogen-activated protein kinases and nuclear factor-κB was impaired after lipopolysaccharide (LPS) stimulation when compared with wild-type astrocytes. In addition, the expression of caveolin-1, not cavin-1, 2, 3, caveolin-2, and flotillin-1, was found to be decreased at the protein and transcriptional levels. FABP7 re-expression in FABP7-KO astrocytes rescued the decreased level of caveolin-1. Furthermore, caveolin-1-transfection into FABP7-KO astrocytes significantly increased TLR4 recruitment into lipid raft and tumor necrosis factor-α production after LPS stimulation. Taken together, these data suggest that FABP7 controls lipid raft function through the regulation of caveolin-1 expression and is involved in the response of astrocytes to the external stimuli. GLIA 2015;63:780-794.

Fatty Acid binding protein 7 is a molecular marker in adenoid cystic carcinoma of the salivary glands: implications for clinical significance

Adenoid cystic carcinoma (ACC) is an aggressive malignant neoplasm of the salivary glands. Its diagnosis is difficult due to overlapping features with other salivary tumors. Gene expression analysis may complement traditional diagnostic methods. We searched gene expression patterns in the Gene Expression Omnibus (GEO) database and in our tumor and normal samples. The biologic and prognostic potential of the identified genes was analyzed. The GEO data set of primary xenografted ACCs revealed that expression of five genes, engrailed homeobox 1 (EN1), fatty acid binding protein 7 (FABP7), hemoglobin epsilon 1, MYB, and versican (VCAN), was dramatically increased. mRNA expression of EN1, FABP7, MYB, and VCAN distinguished our sporadic ACCs from normal tissues and benign tumors. FABP7 expression appeared to be regulated differently from EN1 and MYB and was crossly correlated with poor prognosis in our ACC cohort. Immunohistochemistry showed that FABP7 protein was predominantly expressed in the nucleus of myoepithelial cells of both tubular and cribriform subtypes. In contrast, in the solid subtype, which is often associated with a lower survival rate, FABP7 protein was uniformly expressed in cancerous cells. One case with cribriform architecture and the highest level of FABP7 mRNA showed strong FABP7 staining in both duct-type epithelial and myoepithelial cells, suggesting that diffuse expression of FABP7 protein might be related to aggressive tumor behavior and poor prognosis. We propose FABP7 as a novel biomarker in ACC. The molecule may be useful in diagnosis and for identifying more effective therapies targeting this protein or upstream molecules that regulate it.

Fatty acid uptake and lipid storage induced by HIF-1α contribute to cell growth and survival after hypoxia-reoxygenation

An in vivo model of antiangiogenic therapy allowed us to identify genes upregulated by bevacizumab treatment, including Fatty Acid Binding Protein 3 (FABP3) and FABP7, both of which are involved in fatty acid uptake. In vitro, both were induced by hypoxia in a hypoxia-inducible factor-1α (HIF-1α)-dependent manner. There was a significant lipid droplet (LD) accumulation in hypoxia that was time and O2 concentration dependent. Knockdown of endogenous expression of FABP3, FABP7, or Adipophilin (an essential LD structural component) significantly impaired LD formation under hypoxia. We showed that LD accumulation is due to FABP3/7-dependent fatty acid uptake while de novo fatty acid synthesis is repressed in hypoxia. We also showed that ATP production occurs via β-oxidation or glycogen degradation in a cell-type-dependent manner in hypoxia-reoxygenation. Finally, inhibition of lipid storage reduced protection against reactive oxygen species toxicity, decreased the survival of cells subjected to hypoxia-reoxygenation in vitro, and strongly impaired tumorigenesis in vivo.

Distinct isoform of FABP7 revealed by screening for retroelement-activated genes in diffuse large B-cell lymphoma

Remnants of ancient transposable elements (TEs) are abundant in mammalian genomes. These sequences harbor multiple regulatory motifs and hence are capable of influencing expression of host genes. In response to environmental changes, TEs are known to be released from epigenetic repression and to become transcriptionally active. Such activation could also lead to lineage-inappropriate activation of oncogenes, as one study described in Hodgkin lymphoma. However, little further evidence for this mechanism in other cancers has been reported. Here, we reanalyzed whole transcriptome data from a large cohort of patients with diffuse large B-cell lymphoma (DLBCL) compared with normal B-cell centroblasts to detect genes ectopically expressed through activation of TE promoters. We have identified 98 such TE-gene chimeric transcripts that were exclusively expressed in primary DLBCL cases and confirmed several in DLBCL-derived cell lines. We further characterized a TE-gene chimeric transcript involving a fatty acid-binding protein gene (LTR2-FABP7), normally expressed in brain, that was ectopically expressed in a subset of DLBCL patients through the use of an endogenous retroviral LTR promoter of the LTR2 family. The LTR2-FABP7 chimeric transcript encodes a novel chimeric isoform of the protein with characteristics distinct from native FABP7. In vitro studies reveal a dependency for DLBCL cell line proliferation and growth on LTR2-FABP7 chimeric protein expression. Taken together, these data demonstrate the significance of TEs as regulators of aberrant gene expression in cancer and suggest that LTR2-FABP7 may contribute to the pathogenesis of DLBCL in a subgroup of patients.

Microarray profiling of human renal cell carcinoma: identification for potential biomarkers and critical pathways

AIMS

The aim of this study was to screen several novel genes associated with renal cell carcinoma (RCC), and analyze the gene functions and signal pathways which were critical to RCCs with DNA microarray.

METHODS

The gene expression profile of GSE781 was downloaded from Gene Expression Omnibus database, including 9 RCC samples and 9 healthy controls. Compared with the control samples, differentially expressed genes (DEGs) of RCC was identified the by packages in R. The selected DEGs were further analyzed using bioinformatics methods. Gene ontology (GO) enrichment analysis was performed using Gene Set Analysis Toolkit and protein-protein interaction (PPI) network was constructed with prePPI. Then, pathway enrichment analysis to PPI network was performed using WebGestalt software.

RESULTS

A total of 429 DEGs were down-regulated and 418 DEGs were up-regulated in RCC samples compared to healthy controls. A total of 11 remarkable enhanced functions and 13 suppressed functions were identified. PPI nodes of high degrees, such as JAK2, IL8, BMPR2, FN1 and NCR1, were obtained. The DEGs were classified and significantly enriched in cytokine and cytokine receptor pathway.

CONCLUSION

The hub genes we find from RCC samples are not only bio-markers, but also may provide the groundwork for a combination therapy approach for RCCs.

A radial glia gene marker, fatty acid binding protein 7 (FABP7), is involved in proliferation and invasion of glioblastoma cells

Glioblastoma multiforme (GBM) is among the most deadly cancers. A number of studies suggest that a fraction of tumor cells with stem cell features (Glioma Stem-like Cells, GSC) might be responsible for GBM recurrence and aggressiveness. GSC similarly to normal neural stem cells, can form neurospheres (NS) in vitro, and seem to mirror the genetic features of the original tumor better than glioma cells growing adherently in the presence of serum. Using cDNA microarray analysis we identified a number of relevant genes for glioma biology that are differentially expressed in adherent cells and neurospheres derived from the same tumor. Fatty acid-binding protein 7 (FABP7) was identified as one of the most highly expressed genes in NS compared to their adherent counterpart. We found that down-regulation of FABP7 expression in NS by small interfering RNAs significantly reduced cell proliferation and migration. We also evaluated the potential involvement of FABP7 in response to radiotherapy, as this treatment may cause increased tumor infiltration. Migration of irradiated NS was associated to increased expression of FABP7. In agreement with this, in vivo reduced tumorigenicity of GBM cells with down-regulated expression of FABP7 was associated to decreased expression of the migration marker doublecortin. Notably, we observed that PPAR antagonists affect FABP7 expression and decrease the migration capability of NS after irradiation. As a whole, the data emphasize the role of FABP7 expression in GBM migration and provide translational hints on the timing of treatment with anti-FABP7 agents like PPAR antagonists during GBM evolution.

Synthetic retinoid CD437 induces apoptosis and acts synergistically with TRAIL receptor-2 agonist in malignant melanoma

The novel synthetic retinoid, CD437, shows potent anti-tumor activity in a range of different cancer cell lines and now serves as a prototype for development of new retinoid related molecules (RRMs). The purpose of this study was to examine the effect and cellular targets of CD437 in the human metastatic melanoma cell lines FEMX-1 and WM239. We showed that treatment with CD437 led to cell cycle arrest and induced apoptosis through both the extrinsic- and intrinsic pathways (caspase 8, -9 and PARP cleavage) in both cell lines. Interestingly, apoptosis was induced independently of DNA-fragmentation in FEMX-1 cells, and appeared partially caspase-independent in the WM239 cells. Additionally, up-regulation of CHOP mRNA and cathepsin D protein expression, following retinoid treatment, suggests involvement of the endoplasmatic reticulum (ER) and lysosomes, respectively. Combination of suboptimal concentrations of CD437 and lexatumumab, a TRAIL death receptor-2 agonist, resulted in synergistic reduction of viable cells, along with increased PARP cleavage. These results indicate that CD437 has a strong anti-neoplastic effect alone and in combination with lexatumumab in melanoma cell lines.

Cytoplasmic BRMS1 expression in malignant melanoma is associated with increased disease-free survival

Background/aims

Breast cancer metastasis suppressor 1 (BRMS1) blocks metastasis in melanoma xenografts; however, its usefulness as a biomarker in human melanomas has not been widely studied. The goal was to measure BRMS1 expression in benign nevi, primary and metastatic melanomas and evaluate its impact on disease progression and prognosis.

Methods

Paraffin-embedded tissue from 155 primary melanomas, 69 metastases and 15 nevi was examined for BRMS1 expression using immunohistochemistry. siRNA mediated BRMS1 down-regulation was used to study impact on invasion and migration in melanoma cell lines.

Results

A significantly higher percentage of nevi (87%), compared to primary melanomas (20%) and metastases (48%), expressed BRMS1 in the nucelus (p < 0.0001). Strong nuclear staining intensity was observed in 67% of nevi, and in 9% and 24% of the primary and metastatic melanomas, respectively (p < 0.0001). Comparable cytoplasmic expression was observed (nevi; 87%, primaries; 86%, metastases; 72%). However, a decline in cytoplasmic staining intensity was observed in metastases compared to nevi and primary tumors (26%, 47%, and 58%, respectively, p < 0.0001). Score index (percentage immunopositive celles multiplied with staining intensity) revealed that high cytoplasmic score index (≥ 4) was associated with thinner tumors (p = 0.04), lack of ulceration (p = 0.02) and increased disease-free survival (p = 0.036). When intensity and percentage BRMS1 positive cells were analyzed separately, intensity remained associated with tumor thickness (p = 0.024) and ulceration (p = 0.004) but was inversely associated with expression of proliferation markers (cyclin D3 (p = 0.008), cyclin A (p = 0.007), and p21^Waf1/Cip1 (p = 0.009)). Cytoplasmic score index was inversely associated with nuclear p-Akt (p = 0.013) and positively associated with cytoplasmic p-ERK1/2 expression (p = 0.033). Nuclear BRMS1 expression in ≥ 10% of primary melanoma cells was associated with thicker tumors (p = 0.016) and decreased relapse-free period (p = 0.043). Nuclear BRMS1 was associated with expression of fatty acid binding protein 7 (FABP7; p = 0.011), a marker of invasion in melanomas. In line with this, repression of BRMS1 expression reduced the ability of melanoma cells to migrate and invade in vitro.

Conclusion

Our data suggest that BRMS1 is localized in cytoplasm and nucleus of melanocytic cells and that cellular localization determines its in vivo effect. We hypothesize that cytoplasmic BRMS1 restricts melanoma progression while nuclear BRMS1 possibly promotes melanoma cell invasion.

Please see related article: http://www.biomedcentral.com/1741-7015/10/19

Proteomic analysis of hepatic tissue in adult female zebrafish (Danio rerio) exposed to atrazine

Atrazine (ATZ), the most common herbicide, is a frequently observed contaminant in freshwater ecosystems. In the present study, two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization tandem time-of-flight-mass spectrometry, combined with histopathological analysis, were used to detect the hepatic damage in adult female zebrafish (Danio rerio) exposed to ATZ. More than 600 hepatic protein spots were detected in each gel with silver staining, and most of the proteins ranged from 20 to 70 kD and pH 4-9. Through comparison and analysis, 7 proteins were found to be upregulated>2-fold, whereas 6 protein spots were downregulated>2-fold after 10 and 1000 μg/l ATZ exposures for 14 days, which had caused histological effects in zebrafish livers. We found that these changed proteins were associated with a variety of cellular biological processes, such as response to oxidative stress, oncogenesis, etc. The results demonstrated that ATZ comprehensively influenced a variety of cellular and biological processes in zebrafish. The information presented in this study will be helpful in fully understanding the mechanism of the potential effects induced by ATZ in fish.

Immunohistochemistry: relevance in dermatology

Use of immunohistochemical technique is increasing in diagnosing various diseases. In many situations it may not be possible to differentiate entities with overlapping clinical and histopathological features. Immunostaining of cellular antigens is immensely helpful in such cases. Immunohistochemistry (IHC) has also been in use for targeted cancer therapy. In this article, the discussion will be restricted to use of IHC in dermatological disorders and use of classical antigens with brief updating of some important newly discovered antigens.

Transcriptomic analysis of mouse embryonic skin cells reveals previously unreported genes expressed in melanoblasts

Studying the development of melanoblasts, precursors of melanocytes, is challenging owing to their scarcity and dispersion in the skin embryo. However, this is an important subject because diverse diseases are associated with defective melanoblast development. Consequently, characterizing patterns of expression in melanoblasts during normal development is an important issue. This requires isolating enough melanoblasts during embryonic development to obtain sufficient RNA to study their transcriptome. ZEG reporter mouse line crossed with Tyr::Cre mouse line was used to label melanoblasts by enhanced green fluorescent protein (EGFP) autofluorescence. We isolated melanoblasts by FACS from the skin of E14.5-E16.5 embryos, and obtained sufficient cells for large-scale transcriptomic analysis after RNA isolation and amplification. We confirmed our array-based data for various genes of interest by standard quantitative real-time RT-PCR. We demonstrated that phosphatase and tensin homolog was expressed in melanoblasts but BRN2 was not, although both are involved in melanomagenesis. We also revealed the potential contribution of genes not previously implicated in any function in melanocytes or even in neural crest derivatives. Finally, the Schwann cell markers, PLP1 and FABP7, were significantly expressed in melanoblasts, melanocytes, and melanoma. This study demonstrates the feasibility of the transcriptomic analysis of purified melanoblasts at different embryonic stages and reveals the involvement of previously unreported genes in melanoblast development.

Analysis of the regulation of fatty acid binding protein 7 expression in human renal carcinoma cell lines

Background

Improving the treatment of renal cell carcinoma (RCC) will depend on the development of better biomarkers for predicting disease progression and aiding the design of appropriate therapies. One such marker may be fatty acid binding protein 7 (FABP7), also known as B-FABP and BLBP, which is expressed normally in radial glial cells of the developing central nervous system and cells of the mammary gland. Melanomas, glioblastomas, and several types of carcinomas, including RCC, overexpress FABP7. The abundant expression of FABP7 in primary RCCs compared to certain RCC-derived cell lines may allow the definition of the molecular components of FABP7's regulatory system.

Results

We determined FABP7 mRNA levels in six RCC cell lines. Two were highly expressed, whereas the other and the embryonic kidney cell line (HEK293) were weakly expressed FABP7 transcripts. Western blot analysis of the cell lines detected strong FABP7 expression only in one RCC cell line. Promoter activity in the RCC cell lines was 3- to 21-fold higher than that of HEK293. Deletion analysis demonstrated that three FABP7 promoter regions contributed to upregulated expression in RCC cell lines, but not in the HEK293 cell. Competition analysis of gel shifts indicated that OCT1, OCT6, and nuclear factor I (NFI) bound to the FABP7 promoter region. Supershift experiments indicated that BRN2 (POU3F2) and NFI bound to the FABP7 promoter region as well. There was an inverse correlation between FABP7 promoter activity and BRN2 mRNA expression. The FABP7-positive cell line's NFI-DNA complex migrated faster than in other cell lines. Levels of NFIA mRNA were higher in the HEK293 cell line than in any of the six RCC cell lines. In contrast, NFIC mRNA expression was lower in the HEK293 cell line than in the six RCC cell lines.

Conclusions

Three putative FABP7 promoter regions drive reporter gene expression in RCC cell lines, but not in the HEK293 cell line. BRN2 and NFI may be key factors regulating the expression of FABP7 in certain RCC-derived cell lines.

Fatty acid binding proteins (FABPs) in prostate, bladder and kidney cancer cell lines and the use of IL-FABP as survival predictor in patients with renal cell carcinoma

Background

Fatty acid binding proteins (FABP) play an important role in carcinogenesis. Modified FABP expression patterns were described for prostate, bladder and for renal cell carcinoma. Studies on metabolic relationships and interactions in permanent cell lines allow a deeper insight into molecular processes. The aim of this study is therefore a systematic overview on mRNA and protein expressions of seven FABPs in frequently used urological cell lines.

Methods

Nine cell lines of renal carcinomas, seven of urinary bladder carcinomas, and five of prostate carcinomas were investigated. Quantitative RT-qPCR and western blotting were used to determine different FABPs. In addition, 46 paired cancerous and noncancerous tissue samples from nephrectomy specimen with renal cell carcinomas were investigated regarding the ileum FABP mRNA expression level and associated with survival outcome.

Results

General characteristics of all urological carcinoma cell lines were the expression of E-and IL-FABP on mRNA and protein level, while the expressions differed between the cell lines. The protein expression was not always congruent with the mRNA expression. Renal cell carcinoma cell lines showed expressions of L-, H- and B-FABP mRNA in addition to the general FABP expression in five out of the eight investigated cell lines. In bladder cancer cell lines, we additionally found the expression of A-FABP mRNA in six cell lines, while H-FABP was present only in three cell lines. In prostate cancer cell lines, a strong reduction of A- and E- FABP mRNA was observed. The expression of B-FABP mRNA and protein was observed only in the 22 RV-1 cells. IL-FABP mRNA was over-expressed in renal tumour tissue. The IL-FABP ratio was identified as an independent indicator of survival outcome.

Conclusions

Distinctly different FABP expression patterns were observed not only between the cell lines derived from the three cancer types, but also between the cell lines from the same cancer. The FABP patterns in the cell lines do not always reflect the real situation in the tumours. These facts have to be considered in functional studies concerning the different FABPs.

Brain fatty acid-binding protein and omega-3/omega-6 fatty acids: mechanistic insight into malignant glioma cell migration

Malignant gliomas (MG) are highly infiltrative tumors that consistently recur despite aggressive treatment. Brain fatty acid-binding protein (FABP7), which binds docosahexaenoic acid (DHA) and arachidonic acid (AA), localizes to sites of tumor infiltration and is associated with a poor prognosis in MG. Manipulation of FABP7 expression in MG cell lines affects cell migration, suggesting a role for FABP7 in tumor infiltration and recurrence. Here, we show that DHA inhibits and AA stimulates migration in an FABP7-dependent manner in U87 MG cells. We demonstrate that DHA binds to and sequesters FABP7 to the nucleus, resulting in decreased cell migration. This anti-migratory effect is partially dependent on peroxisome proliferator-activated receptor γ, a DHA-activated transcription factor. Conversely, AA-bound FABP7 stimulates cell migration by activating cyclooxygenase-2 and reducing peroxisome proliferator-activated receptor γ levels. Our data provide mechanistic insight as to why FABP7 is associated with a poor prognosis in MG and suggest that relative levels of DHA and AA in the tumor environment can make a profound impact on tumor growth properties. We propose that FABP7 and its fatty acid ligands may be key therapeutic targets for controlling the dissemination of MG cells within the brain.

Biomarkers: the useful and the not so useful--an assessment of molecular prognostic markers for cutaneous melanoma

Among individuals with localized (Stage I-II) melanoma, stratifying patients by a number of phenotypic variables (e.g., depth of invasion, ulceration) yields a wide range of 10-year melanoma-specific survival rates. With the possible exception of Ki-67, no molecular assessment is routinely used. However, there have been a tremendous number of studies assessing protein expression by immunohistochemistry toward the goal of better prediction of recurrence. In a previous systematic review, which required publication of multivariable prognostic models as a strict inclusion criterion, we identified 37 manuscripts that collectively reported on 62 proteins. Data for 324 proteins extracted from 418 manuscripts did not meet our inclusion criteria for that study, but are revisited here, emphasizing trends of protein expression across either melanocytic lesion progression or gradations of tumor thickness. These identified 101 additional proteins that stratify melanoma, organized according to the Hanahan and Weinberg functional capabilities of cancer.

Cutaneous short-interfering RNA therapy

Since the 1990s, RNA interference (RNAi) has become a major subject of interest, not only as a tool for biological research, but also, more importantly, as a therapeutic approach for gene-related diseases. The use of short-interfering RNAs (siRNAs) for the sequence-specific knockdown of disease-causing genes has led to numerous preclinical and even a few clinical studies. Applications for cutaneous delivery of therapeutic siRNA are now emerging owing to a strong demand for effective treatments of various cutaneous disorders. Although successful studies have been performed using several different delivery techniques, most of these techniques encounter limitations for translation to the clinic with regards to patient compliance. This review describes the principal findings and applications in cutaneous RNAi therapy and focuses on the promises and pitfalls of the delivery systems.