Fatty acid synthase: a novel target for antiglioma therapy

A proteomic approach supports the clinical relevance of TAT-Cx43266-283 in glioblastoma

Glioblastoma (GBM) is the most frequent and aggressive primary brain cancer. The Src inhibitor, TAT-Cx43266-283, exerts antitumor effects in in vitro and in vivo models of GBM. Because addressing the mechanism of action is essential to translate these results to a clinical setting, in this study we carried out an unbiased proteomic approach. Data-independent acquisition mass spectrometry proteomics allowed the identification of 190 proteins whose abundance was modified by TAT-Cx43266-283. Our results were consistent with the inhibition of Src as the mechanism of action of TAT-Cx43266-283 and unveiled antitumor effectors, such as p120 catenin. Changes in the abundance of several proteins suggested that TAT-Cx43266-283 may also impact the brain microenvironment. Importantly, the proteins whose abundance was reduced by TAT-Cx43266-283 correlated with an improved GBM patient survival in clinical datasets and none of the proteins whose abundance was increased by TAT-Cx43266-283 correlated with shorter survival, supporting its use in clinical trials.

Suppressing Wnt signaling of the blood‒tumor barrier to intensify drug delivery and inhibit lipogenesis of brain metastases

Lipogenesis is often highly upregulated in breast cancer brain metastases to adapt to intracranial low lipid microenvironments. Lipase inhibitors hold therapeutic potential but their intra-tumoral distribution is often blocked by the blood‒tumor barrier (BTB). BTB activates its Wnt signaling to maintain barrier properties, e.g., Mfsd2a-mediated BTB low transcytosis. Here, we reported VCAM-1-targeting nano-wogonin (W@V-NPs) as an adjuvant of nano-orlistat (O@V-NPs) to intensify drug delivery and inhibit lipogenesis of brain metastases. W@V-NPs were proven to be able to inactivate BTB Wnt signaling, downregulate BTB Mfsd2a, accelerate BTB vesicular transport, and enhance tumor accumulation of O@V-NPs. With the ability to specifically kill cancer cells in a lipid-deprived environment with IC50 at 48 ng/mL, W@V-NPs plus O@V-NPs inhibited the progression of brain metastases with prolonged survival of model mice. The combination did not induce brain edema, cognitive impairment, and systemic toxicity in healthy mice. Targeting Wnt signaling could safely modulate the BTB to improve drug delivery and metabolic therapy against brain metastases.

Emerging Lipid Targets in Glioblastoma

GBM accounts for most of the fatal brain cancer cases, making it one of the deadliest tumor types. GBM is characterized by severe progression and poor prognosis with a short survival upon conventional chemo- and radiotherapy. In order to improve therapeutic efficiency, considerable efforts have been made to target various features of GBM. One of the targetable features of GBM is the rewired lipid metabolism that contributes to the tumor's aggressive growth and penetration into the surrounding brain tissue. Lipid reprogramming allows GBM to acquire survival, proliferation, and invasion benefits as well as supportive modulation of the tumor microenvironment. Several attempts have been made to find novel therapeutic approaches by exploiting the lipid metabolic reprogramming in GBM. In recent studies, various components of de novo lipogenesis, fatty acid oxidation, lipid uptake, and prostaglandin synthesis have been considered promising targets in GBM. Emerging data also suggest a significant role hence therapeutic potential of the endocannabinoid metabolic pathway in GBM. Here we review the lipid-related GBM characteristics in detail and highlight specific targets with their potential therapeutic use in novel antitumor approaches.

Role of Glycolytic and Glutamine Metabolism Reprogramming on the Proliferation, Invasion, and Apoptosis Resistance through Modulation of Signaling Pathways in Glioblastoma

Glioma cells exhibit genetic and metabolic alterations that affect the deregulation of several cellular signal transduction pathways, including those related to glucose metabolism. Moreover, oncogenic signaling pathways induce the expression of metabolic genes, increasing the metabolic enzyme activities and thus the critical biosynthetic pathways to generate nucleotides, amino acids, and fatty acids, which provide energy and metabolic intermediates that are essential to accomplish the biosynthetic needs of glioma cells. In this review, we aim to explore how dysregulated metabolic enzymes and their metabolites from primary metabolism pathways in glioblastoma (GBM) such as glycolysis and glutaminolysis modulate anabolic and catabolic metabolic pathways as well as pro-oncogenic signaling and contribute to the formation, survival, growth, and malignancy of glioma cells. Also, we discuss promising therapeutic strategies by targeting the key players in metabolic regulation. Therefore, the knowledge of metabolic reprogramming is necessary to fully understand the biology of malignant gliomas to improve patient survival significantly.

Glioblastoma Metabolism: Insights and Therapeutic Strategies

Tumor metabolism is emerging as a potential target for cancer therapies. This new approach holds particular promise for the treatment of glioblastoma, a highly lethal brain tumor that is resistant to conventional treatments, for which improving therapeutic strategies is a major challenge. The presence of glioma stem cells is a critical factor in therapy resistance, thus making it essential to eliminate these cells for the long-term survival of cancer patients. Recent advancements in our understanding of cancer metabolism have shown that glioblastoma metabolism is highly heterogeneous, and that cancer stem cells exhibit specific metabolic traits that support their unique functionality. The objective of this review is to examine the metabolic changes in glioblastoma and investigate the role of specific metabolic processes in tumorigenesis, as well as associated therapeutic approaches, with a particular focus on glioma stem cell populations.

Re-convolving the compositional landscape of primary and recurrent glioblastoma reveals prognostic and targetable tissue states

Glioblastoma (GBM) diffusely infiltrates the brain and intermingles with non-neoplastic brain cells, including astrocytes, neurons and microglia/myeloid cells. This complex mixture of cell types forms the biological context for therapeutic response and tumor recurrence. We used single-nucleus RNA sequencing and spatial transcriptomics to determine the cellular composition and transcriptional states in primary and recurrent glioma and identified three compositional 'tissue-states' defined by cohabitation patterns between specific subpopulations of neoplastic and non-neoplastic brain cells. These tissue-states correlated with radiographic, histopathologic, and prognostic features and were enriched in distinct metabolic pathways. Fatty acid biosynthesis was enriched in the tissue-state defined by the cohabitation of astrocyte-like/mesenchymal glioma cells, reactive astrocytes, and macrophages, and was associated with recurrent GBM and shorter survival. Treating acute slices of GBM with a fatty acid synthesis inhibitor depleted the transcriptional signature of this pernicious tissue-state. These findings point to therapies that target interdependencies in the GBM microenvironment.

Biosynthesis and Significance of Fatty Acids, Glycerophospholipids, and Triacylglycerol in the Processes of Glioblastoma Tumorigenesis

One area of glioblastoma research is the metabolism of tumor cells and detecting differences between tumor and healthy brain tissue metabolism. Here, we review differences in fatty acid metabolism, with a particular focus on the biosynthesis of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) by fatty acid synthase (FASN), elongases, and desaturases. We also describe the significance of individual fatty acids in glioblastoma tumorigenesis, as well as the importance of glycerophospholipid and triacylglycerol synthesis in this process. Specifically, we show the significance and function of various isoforms of glycerol-3-phosphate acyltransferases (GPAT), 1-acylglycerol-3-phosphate O-acyltransferases (AGPAT), lipins, as well as enzymes involved in the synthesis of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), and cardiolipin (CL). This review also highlights the involvement of diacylglycerol O-acyltransferase (DGAT) in triacylglycerol biosynthesis. Due to significant gaps in knowledge, the GEPIA database was utilized to demonstrate the significance of individual enzymes in glioblastoma tumorigenesis. Finally, we also describe the significance of lipid droplets in glioblastoma and the impact of fatty acid synthesis, particularly docosahexaenoic acid (DHA), on cell membrane fluidity and signal transduction from the epidermal growth factor receptor (EGFR).

Development of [18F]F-5-OMe-Tryptophans through Photoredox Radiofluorination: A New Method to Access Tryptophan-Based PET Agents

Although various radiolabeled tryptophan analogs have been developed to monitor tryptophan metabolism using positron emission tomography (PET) for various human diseases including melanoma and other cancers, their application can be limited due to the complicated synthesis process. In this study, we demonstrated that photoredox radiofluorination represents a simple method to access novel tryptophan-based PET agents. In brief, 4-F-5-OMe-tryptophans (l/d-T13) and 6-F-5-OMe-tryptophans (l/d-T18) were easily synthesized. The 18F-labeled analogs were produced by photoredox radiofluorination with radiochemical yields ranging from 2.6 ± 0.5% to 32.4 ± 4.1% (3 ≤ n ≤ 5, enantiomeric excess ≥ 99.0%) and over 98.0% radiochemical purity. Small animal imaging showed that l-[18F]T13 achieved 9.58 ± 0.26%ID/g tumor uptake and good contrast in B16F10 tumor-bearing mice (n = 3). Clearly, l-[18F]T13 exhibited prominent tumor uptake, warranting future evaluations of its potential usage in precise immunotherapy monitoring.

Targeting fatty acid metabolism in glioblastoma

Glioblastoma (GBM) is a primary tumor of the brain defined by its uniform lethality and resistance to conventional therapies. There have been considerable efforts to untangle the metabolic underpinnings of this disease to find novel therapeutic avenues for treatment. An emerging focus in this field is fatty acid (FA) metabolism, which is critical for numerous diverse biological processes involved in GBM pathogenesis. These processes can be classified into four broad fates: anabolism, catabolism, regulation of ferroptosis, and the generation of signaling molecules. Each fate provides a unique perspective by which we can inspect GBM biology and gives us a road map to understanding this complicated field. This Review discusses the basic, translational, and clinical insights into each of these fates to provide a contemporary understanding of FA biology in GBM. It is clear, based on the literature, that there are far more questions than answers in the field of FA metabolism in GBM, and substantial efforts should be made to untangle these complex processes in this intractable disease.

Cellular signals integrate cell cycle and metabolic control in cancer

Growth factors are the small peptides that can promote growth, differentiation, and survival of most living cells. However, aberrant activation of receptor tyrosine kinases by GFs can generate oncogenic signals, resulting in oncogenic transformation. Accumulating evidence support a link between GF/RTK signaling through the major signaling pathways, Ras/Erk and PI3K/Akt, and cell cycle progression. In response to GF signaling, the quiescent cells in the G₀ stage can re-enter the cell cycle and become the proliferative stage. While in the proliferative stage, tumor cells undergo profound changes in their metabolism to support biomass production and bioenergetic requirements. Accumulating data show that the cell cycle regulators, specifically cyclin D, cyclin B, Cdk2, Cdk4, and Cdk6, and anaphase-promoting complex/cyclosome (APC/C-Cdh1) play critical roles in modulating various metabolic pathways. These cell cycle regulators can regulate metabolic enzyme activities through post-translational mechanisms or the transcriptional factors that control the expression of the metabolic genes. This fine-tune control allows only the relevant metabolic pathways to be active in a particular phase of the cell cycle, thereby providing suitable amounts of biosynthetic precursors available during the proliferative stage. The imbalance of metabolites in each cell cycle phase can induce cell cycle arrest followed by p53-induced apoptosis.

Inhibition of Fatty Acid Synthesis Aggravates Brain Injury, Reduces Blood-Brain Barrier Integrity and Impairs Neurological Recovery in a Murine Stroke Model

Inhibition of fatty acid synthesis (FAS) stimulates tumor cell death and reduces angiogenesis. When SH-SY5Y cells or primary neurons are exposed to hypoxia only, inhibition of FAS yields significantly enhanced cell injury. The pathophysiology of stroke, however, is not only restricted to hypoxia but also includes reoxygenation injury. Hence, an oxygen-glucose-deprivation (OGD) model with subsequent reoxygenation in both SH-SY5Y cells and primary neurons as well as a murine stroke model were used herein in order to study the role of FAS inhibition and its underlying mechanisms. SH-SY5Y cells and cortical neurons exposed to 10 h of OGD and 24 h of reoxygenation displayed prominent cell death when treated with the Acetyl-CoA carboxylase inhibitor TOFA or the fatty acid synthase inhibitor cerulenin. Such FAS inhibition reduced the reduction potential of these cells, as indicated by increased NADH₂ ⁺/NAD⁺ ratios under both in vitro and in vivo stroke conditions. As observed in the OGD model, FAS inhibition also resulted in increased cell death in the stroke model. Stroke mice treated with cerulenin did not only display increased brain injury but also showed reduced neurological recovery during the observation period of 4 weeks. Interestingly, cerulenin treatment enhanced endothelial cell leakage, reduced transcellular electrical resistance (TER) of the endothelium and contributed to poststroke blood-brain barrier (BBB) breakdown. The latter was a consequence of the activated NF-κB pathway, stimulating MMP-9 and ABCB1 transporter activity on the luminal side of the endothelium. In conclusion, FAS inhibition aggravated poststroke brain injury as consequence of BBB breakdown and NF-κB-dependent inflammation.

Metabolic Drivers of Invasion in Glioblastoma

Glioblastoma is a primary malignant brain tumor with a median survival under 2 years. The poor prognosis glioblastoma caries is largely due to cellular invasion, which enables escape from resection, and drives inevitable recurrence. While most studies to date have focused on pathways that enhance the invasiveness of tumor cells in the brain microenvironment as the primary driving forces behind GBM’s ability to invade adjacent tissues, more recent studies have identified a role for adaptations in cellular metabolism in GBM invasion. Metabolic reprogramming allows invasive cells to generate the energy necessary for colonizing surrounding brain tissue and adapt to new microenvironments with unique nutrient and oxygen availability. Historically, enhanced glycolysis, even in the presence of oxygen (the Warburg effect) has dominated glioblastoma research with respect to tumor metabolism. More recent global profiling experiments, however, have identified roles for lipid, amino acid, and nucleotide metabolism in tumor growth and invasion. A thorough understanding of the metabolic traits that define invasive GBM cells may provide novel therapeutic targets for this devastating disease. In this review, we focus on metabolic alterations that have been characterized in glioblastoma, the dynamic nature of tumor metabolism and how it is shaped by interaction with the brain microenvironment, and how metabolic reprogramming generates vulnerabilities that may be ripe for exploitation.

Body mass index as an independent prognostic factor in glioblastoma

PURPOSE

Glioblastoma prognosis remains dismal despite gross total removal (GTR) followed by chemoradiotherapy. Other known prognostic factors include functional status, age and IDH mutation status. However, to improve patient outcome, a search for other features with impact on survival is needed. We aimed to analyse the impact of body mass index (BMI) on overall survival (OS) and progression-free survival (PFS) of surgically resected primary glioblastoma and evaluate if BMI constitutes an independent prognostic factor.

METHODS

We analysed all adult glioblastoma patients who underwent surgery and chemoradiotherapy between 2011 and 2017 at our institution. Overall survival was the study-primary endpoint, and progression-free survival-the secondary endpoint. We assayed age, gender, histology, extent of resection, IDH, functional and smoking status, cardiovascular risk factors, BMI, OS and PFS. Univariate analysis was conducted followed by multivariate analysis to establish independent prognostic factors. In accordance with the World Health Organization (WHO) BMI stratification, survival curves were obtained for normal-weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²) and obese (≥ 30 kg/m²) patient subgroups in addition to the non-obese (18.5-29.9 kg/m²) population.

RESULTS

193 patients were evaluated, with a median follow-up time of 17.3 months. Median OS was 21.3 months in obese patients vs 16.2 months in the non-obese (p = 0.017) and 16 months in the normal weight (p = 0.007). Higher median OS was also observed in patients under 60 and those in which GTR was obtained. Median PFS in obese individuals was 9 months in comparison to 6 months in the normal-weight subgroup (p = 0.04) and 7 months in the non-obese (p = 0.050). Multivariate analysis identified age < 60 (p = 0.044), GTR (p = 0.004) and BMI ≥ 30 (p = 0.009) as independent prognostic factors for increased overall survival.

CONCLUSION

Higher BMI was associated with longer OS and PFS. Prospective studies are needed to validate these findings.

3D DESI-MS lipid imaging in a xenograft model of glioblastoma: a proof of principle

Desorption electrospray ionisation mass spectrometry (DESI-MS) can image hundreds of molecules in a 2D tissue section, making it an ideal tool for mapping tumour heterogeneity. Tumour lipid metabolism has gained increasing attention over the past decade; and here, lipid heterogeneity has been visualised in a glioblastoma xenograft tumour using 3D DESI-MS imaging. The use of an automatic slide loader automates 3D imaging for high sample-throughput. Glioblastomas are highly aggressive primary brain tumours, which display heterogeneous characteristics and are resistant to chemotherapy and radiotherapy. It is therefore important to understand biochemical contributions to their heterogeneity, which may be contributing to treatment resistance. Adjacent sections to those used for DESI-MS imaging were used for H&E staining and immunofluorescence to identify different histological regions, and areas of hypoxia. Comparing DESI-MS imaging with biological staining allowed association of different lipid species with hypoxic and viable tissue within the tumour, and hence mapping of molecularly different tumour regions in 3D space. This work highlights that lipids are playing an important role in the heterogeneity of this xenograft tumour model, and DESI-MS imaging can be used for lipid 3D imaging in an automated fashion to reveal heterogeneity, which is not apparent in H&E stains alone.

Integrative cross-platform analyses identify enhanced heterotrophy as a metabolic hallmark in glioblastoma

BACKGROUND

Although considerable progress has been made in understanding molecular alterations driving gliomagenesis, the diverse metabolic programs contributing to the aggressive phenotype of glioblastoma remain unclear. The aim of this study was to define and provide molecular context to metabolic reprogramming driving gliomagenesis.

METHODS

Integrative cross-platform analyses coupling global metabolomic profiling with genomics in patient-derived glioma (low-grade astrocytoma [LGA; n = 28] and glioblastoma [n = 80]) were performed. Identified programs were then metabolomically, genomically, and functionally evaluated in preclinical models.

RESULTS

Clear metabolic programs were identified differentiating LGA from glioblastoma, with aberrant lipid, peptide, and amino acid metabolism representing dominant metabolic nodes associated with malignant transformation. Although the metabolomic profiles of glioblastoma and LGA appeared mutually exclusive, considerable metabolic heterogeneity was observed in glioblastoma. Surprisingly, integrative analyses demonstrated that O6-methylguanine-DNA methyltransferase methylation and isocitrate dehydrogenase mutation status were equally distributed among glioblastoma metabolic profiles. Transcriptional subtypes, on the other hand, tightly clustered by their metabolomic signature, with proneural and mesenchymal tumor profiles being mutually exclusive. Integrating these metabolic phenotypes with gene expression analyses uncovered tightly orchestrated and highly redundant transcriptional programs designed to support the observed metabolic programs by actively importing these biochemical substrates from the microenvironment, contributing to a state of enhanced metabolic heterotrophy. These findings were metabolomically, genomically, and functionally recapitulated in preclinical models.

CONCLUSION

Despite disparate molecular pathways driving the progression of glioblastoma, metabolic programs designed to maintain its aggressive phenotype remain conserved. This contributes to a state of enhanced metabolic heterotrophy supporting survival in diverse microenvironments implicit in this malignancy.

FASN Is a Biomarker Enriched in Malignant Glioma-Derived Extracellular Vesicles

Extracellular vesicles (EVs) are known for their important role in cancer progression and hold considerable potential as a source for tumor biomarkers. However, purification of tumor-specific EVs from patient plasma is still an urgent unmet need due to contamination by normal host cell-derived EVs, that results in compromised analytical sensitivity. Here we identified fatty acid synthase (FASN), a key lipogenic enzyme which is highly expressed in malignant glioma cells, to be elevated in CD63- and CD81-positive EVs in glioma patient plasma samples, opening vital opportunities to sort brain tumor-specific EVs.

Crocetin Extracted from Saffron Shows Antitumor Effects in Models of Human Glioblastoma

Over recent years, many authors discussed the effects of different natural compounds on glioblastoma (GBM). Due to its capacity to impair survival and progression of different cancer types, saffron extract (SE), named crocetin (CCT), is particularly noteworthy. In this work, we elucidated the antitumor properties of crocetin in glioma in vivo and in vitro models for the first time. The in vitro results showed that the four tumor cell lines observed in this study (U251, U87, U138, and U373), which were treated with increasing doses of crocetin, showed antiproliferative and pro-differentiative effects as demonstrated by a significant reduction in the number of viable cells, deep changes in cell morphology, and the modulation of mesenchymal and neuronal markers. Indeed, crocetin decreased the expression of Cluster of Differentiation CD44, CD90, CXCR4, and OCT3/4 mesenchymal markers, but increased the expression of βIII-Tubulin and neurofilaments (NFH) neuronal linage-related markers. Epigenetic mechanisms may modulate these changes, since Histone Deacetylase, HDAC1 and HDAC3 were downmodulated in U251 and U87 cells, whereas HDAC1 expression was downmodulated in U138 and U373 cells. Western blotting analyses of Fatty Acid Synthase, FASN, and CD44 resulted in effective inhibition of these markers after CCT treatment, which was associated with important activation of the apoptosis program and reduced glioma cell movement and wound repair. The in vivo studies aligned with the results obtained in vitro. Indeed, crocetin was demonstrated to inhibit the growth of U251 and U87 cells that were subcutaneously injected into animal models. In particular, the Tumor To Progression or TTP values and Kaplan-Meier curves indicated that crocetin had more major effects than radiotherapy alone, but similar effects to temozolomide (TMZ). An intra-brain cell inoculation of a small number of luciferase-transfected U251 cells provided a model that was able to recapitulate recurrence after surgical tumor removal. The results obtained from the orthotopic intra-brain model indicated that CCT treatment increased the disease-free survival (DFS) and overall survival (OS) rates, inducing a delay in appearance of a detectable bioluminescent lesion. CCT showed greater efficacy than Radio Therapy (RT) but comparable efficacy to temozolomide in xenograft models. Therefore, we aimed to continue the study of crocetin's effects in glioma disease, focusing our attention on the radiosensitizing properties of the natural compound and highlighting the ways in which this was realized.

Systematically understanding the immunity leading to CRPC progression

Prostate cancer (PCa) is the most commonly diagnosed malignancy and the second leading cause of cancer-related death in American men. Androgen deprivation therapy (ADT) has become a standard treatment strategy for advanced PCa. Although a majority of patients initially respond to ADT well, most of them will eventually develop castration-resistant PCa (CRPC). Previous studies suggest that ADT-induced changes in the immune microenvironment (mE) in PCa might be responsible for the failures of various therapies. However, the role of the immune system in CRPC development remains unclear. To systematically understand the immunity leading to CRPC progression and predict the optimal treatment strategy in silico, we developed a 3D Hybrid Multi-scale Model (HMSM), consisting of an ODE system and an agent-based model (ABM), to manipulate the tumor growth in a defined immune system. Based on our analysis, we revealed that the key factors (e.g. WNT5A, TRAIL, CSF1, etc.) mediated the activation of PC-Treg and PC-TAM interaction pathways, which induced the immunosuppression during CRPC progression. Our HMSM model also provided an optimal therapeutic strategy for improving the outcomes of PCa treatment.

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in American men. Androgen deprivation therapy (ADT) is the first-line therapy for advanced PCa, yet a significant number of primary PCa patients treated with ADT eventually develop incurable castration-resistant prostate cancer (CRPC). Recent observations suggest that the immunosuppressive microenvironment of PCa might be responsible for the failures of various therapies. However, the role of immune system in CRPC progression is still unclear. To deeply understand the immunity leading to CRPC progression, we developed a unique systems biology approach (HMSM). Based on our analysis, we identified the key molecules (e.g. WNT5A, TRAIL, CSF1, etc.) mediating the communication of PCa and immune cells. Our HMSM system also revealed the optimal therapeutic strategy for PCa treatment. Collectively, our study provides a new insight to study tumor-related immune mechanisms and pave the way for the development of more effective treatments.

The pro-tumorigenic effects of metabolic alterations in glioblastoma including brain tumor initiating cells

De-regulated cellular energetics is an emerging hallmark of cancer with alterations to glycolysis, oxidative phosphorylation, the pentose phosphate pathway, lipid oxidation and synthesis and amino acid metabolism. Understanding and targeting of metabolic reprogramming in cancers may yield new treatment options, but metabolic heterogeneity and plasticity complicate this strategy. One highly heterogeneous cancer for which current treatments ultimately fail is the deadly brain tumor glioblastoma. Therapeutic resistance, within glioblastoma and other solid tumors, is thought to be linked to subsets of tumor initiating cells, also known as cancer stem cells. Recent profiling of glioblastoma and brain tumor initiating cells reveals changes in metabolism, as compiled here, that may be more broadly applicable. We will summarize the profound role for metabolism in tumor progression and therapeutic resistance and discuss current approaches to target glioma metabolism to improve standard of care.

The role of SH3GL3 in myeloma cell migration/invasion, stemness and chemo-resistance

Multiple myeloma (MM) is an incurable cancer characterized by clonal expansion of malignant plasma cells in the bone marrow and their egress into peripheral blood. The mechanisms of myeloma cells migration/invasion have remained unclear. Herein, we found SH3GL3 was highly expressed in the CD138-negative (CD138⁻) myeloma cells. The migration/invasion capability of CD138⁻ cells was significantly higher than that in the CD138-positive (CD138⁺) cells. Silencing SH3GL3 using shRNA reduced myeloma cells migration/invasion. Conversely, overexpression of SH3GL3 increased myeloma cells migration/invasion. Moreover, SH3GL3 is also associated with the stemness and chemo-resistance of CD138⁻ myeloma cells. Elevated expression of stem cell and multi-drug resistant markers were seen in the myeloma cells with overexpressed SH3GL3; while knocking-down SH3GL3 reduced the expression of these markers. A marked increase in p-PI3K and p-FAK was observed in the cells with overexpressed SH3GL3. To test if FAK/PI3K signaling pathway was involved in the SH3GL3-mediated myeloma cells migration, the cells transfected w/wo SH3GL3 cDNA were treated with FAK inhibitor 14 and PI3K inhibitor LY294002. Inhibition of FAK and PI3K attenuated SH3GL3-mediated migration /invasion. Our findings indicate that SH3GL3 plays an important role in myeloma cell migration/invasion, stemness and chemo-resistance. The SH3GL3-mediated myeloma cell migration/invasion is mediated by FAK/PI3K signaling pathway.

Inhibition of Fatty Acid Synthase Decreases Expression of Stemness Markers in Glioma Stem Cells

Cellular metabolic changes, especially to lipid metabolism, have recently been recognized as a hallmark of various cancer cells. However, little is known about the significance of cellular lipid metabolism in the regulation of biological activity of glioma stem cells (GSCs). In this study, we examined the expression and role of fatty acid synthase (FASN), a key lipogenic enzyme, in GSCs. In the de novo lipid synthesis assay, GSCs exhibited higher lipogenesis than differentiated non-GSCs. Western blot and immunocytochemical analyses revealed that FASN is strongly expressed in multiple lines of patient-derived GSCs (G144 and Y10), but its expression was markedly reduced upon differentiation. When GSCs were treated with 20 μM cerulenin, a pharmacological inhibitor of FASN, their proliferation and migration were significantly suppressed and de novo lipogenesis decreased. Furthermore, following cerulenin treatment, expression of the GSC markers nestin, Sox2 and fatty acid binding protein (FABP7), markers of GCSs, decreased while that of glial fibrillary acidic protein (GFAP) expression increased. Taken together, our results indicate that FASN plays a pivotal role in the maintenance of GSC stemness, and FASN-mediated de novo lipid biosynthesis is closely associated with tumor growth and invasion in glioblastoma.

Fatty acid synthase is a metabolic oncogene targetable in malignant peripheral nerve sheath tumors

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are soft tissue sarcomas with minimal therapeutic opportunities. We observed that lipid droplets (LDs) accumulate in human MPNST cell lines and in primary human tumor samples. The goal of this study was to investigate the relevance of lipid metabolism to MPNST survival and as a possible therapeutic target.

METHODS

Based on preliminary findings that MPNSTs accumulate LDs, we hypothesized that a deregulated lipid metabolism supports MPNST cell survival/proliferation rate. To test this, we examined respiration, role of fatty acid oxidation (FAO), and the enzyme fatty acid synthase involved in de novo fatty acid synthesis in MPNSTs using both genetic and pharmacological tools.

RESULTS

We demonstrate that LDs accumulate in MPNST cell lines, primary human and mouse MPNST tumors, and neural crest cells. LDs from MPNST cells disappear on lipid deprivation, indicating that LDs can be oxidized as a source of energy. Inhibition of FAO decreased oxygen consumption and reduced MPNST survival, indicating that MPNST cells likely metabolize LDs through active FAO. FAO inhibition reduced oxygen consumption and survival even in the absence of exogenous lipids, indicating that lipids synthesized de novo can also be oxidized. Consequently, inhibition of de novo fatty acid synthesis, which is overexpressed in human MPNST cell lines, effectively reduced MPNST survival and delayed induction of tumor growth in vivo.

CONCLUSION

Our results show that MPNSTs depend on lipid metabolic pathways and suggest that disrupting lipid metabolism could be a potential new strategy for the development of MPNST therapeutics.

Lipoprotein internalisation induced by oncogenic AMPK activation is essential to maintain glioblastoma cell growth

AIM OF THE STUDY

Metabolic adaptations are essential during tumour growth to maintain the high proliferation levels exhibited by cancer cells. In this study, we examined the transformations that occurred in the lipid metabolism in astrocytic tumours, and the possible role of the fuel-sensing enzyme AMPK. Metabolic targets might help design new and effective drugs for cancer.

METHODS

To accomplish this objective, we studied both mice and human astrocytic tumours. We first used a mouse model of astrocytoma driven by oncogenic H-RasV12 and/or with PTEN deletion based on the common constitutive activation of the Raf/MEK/ERK and PI3K/AKT cascades in human astrocytomas. We then confirmed the results in human glioblastoma cell lines and in glioblastoma tissue samples from patients.

RESULTS

We show that the high levels of activated AMPK, observed in astrocytic tumours, increase extracellular lipid internalisation and reduce energy expenditure by inhibiting 'de novo' fatty acid (FA) synthesis, which allows tumour cells to obtain building blocks and energy to be able to create new organelles and new cells.

CONCLUSIONS

Our findings demonstrate that AMPK plays a crucial role in glioblastoma cell growth and suggest that blocking lipoprotein receptors could potentially be used as a plausible therapeutic approach for these and other type of tumours with high levels of AMPK.

Actin cytoskeleton organization, cell surface modification and invasion rate of 5 glioblastoma cell lines differing in PTEN and p53 status

Glioblastoma cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores the relationship between the invasion capacity of 5 glioblastoma cell lines differing in p53 and PTEN status, expression of mTOR and several other marker proteins involved in cell invasion, actin cytoskeleton organization and cell morphology. We found that two glioblastoma lines mutated in both p53 and PTEN genes (U373-MG and SNB19) exhibited the highest invasion rates through the Matrigel or collagen matrix. In DK-MG (p53wt/PTENwt) and GaMG (p53mut/PTENwt) cells, F-actin mainly occurred in the numerous stress fibers spanning the cytoplasm, whereas U87-MG (p53wt/PTENmut), U373-MG and SNB19 (both p53mut/PTENmut) cells preferentially expressed F-actin in filopodia and lamellipodia. Scanning electron microscopy confirmed the abundant filopodia and lamellipodia in the PTEN mutated cell lines. Interestingly, the gene profiling analysis revealed two clusters of cell lines, corresponding to the most (U373-MG and SNB19, i.e. p53 and PTEN mutated cells) and less invasive phenotypes. The results of this study might shed new light on the mechanisms of glioblastoma invasion.

Overexpression of fatty acid synthase in human gliomas correlates with the WHO tumor grade and inhibition with Orlistat reduces cell viability and triggers apoptosis

Fatty acid synthase (FASN), catalyzing the de novo synthesis of fatty acids, is known to be deregulated in several cancers. Inhibition of this enzyme reduces tumor cell proliferation. Unfortunately, adverse effects and chemical instability prevent the in vivo use of the best-known inhibitors, Cerulenin and C75. Orlistat, a drug used for obesity treatment, is also considered as a potential FASN inhibitor, but its impact on glioma cell biology has not yet been described. In this study, we analyzed FASN expression in human glioma samples and primary glioblastoma cell cultures and the effects of FASN inhibition with Orlistat, Cerulenin and C75. Immunohistochemistry followed by densitometric analysis of 20 glioma samples revealed overexpression of FASN that correlated with the WHO tumor grade. Treatment of glioblastoma cells with these inhibitors resulted in a significant, dose-dependent reduction in tumor cell viability and fatty acid synthesis. Compared to Cerulenin and C75, Orlistat was a more potent inhibitor in cell cultures and cell lines. In LN229, cell-growth was reduced by 63.9 ± 8.7 % after 48 h and 200 µM Orlistat compared to controls; in LT68, the reduction in cell growth was 76.3 ± 23.7 %. Nuclear fragmentation assay and Western blotting analysis after targeting FASN with Orlistat demonstrated autophagy and apoptosis. Organotypic slice cultures treated with Orlistat showed reduced proliferation after Ki67 staining and increased caspase-3 cleavage. Our results suggest that FASN may be a therapeutic target in malignant gliomas and identify Orlistat as a possible anti-tumor drug in this setting.

Cell surface area and membrane folding in glioblastoma cell lines differing in PTEN and p53 status

Glioblastoma multiforme (GBM) is characterized by rapid growth, invasion and resistance to chemo−/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM), the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT) technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN) exhibited the lowest degree of membrane folding, probed by the area-specific capacitance C_m = 1.9 µF/cm². In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19) showed the highest C_m values of 3.7–4.0 µF/cm², which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the migration and invasion of GBM and other tumor types.

Fatty acid synthase is a key target in multiple essential tumor functions of prostate cancer: uptake of radiolabeled acetate as a predictor of the targeted therapy outcome

Fatty acid synthase (FASN) expression is elevated in several cancers, and this over-expression is associated with poor prognosis. Inhibitors of FASN, such as orlistat, reportedly show antitumor effects against cancers that over-express FASN, making FASN a promising therapeutic target. However, large variations in FASN expression levels in individual tumors have been observed, and methods to predict FASN-targeted therapy outcome before treatment are required to avoid unnecessary treatment. In addition, how FASN inhibition affects tumor progression remains unclear. Here, we showed the method to predict FASN-targeted therapy outcome using radiolabeled acetate uptake and presented mechanisms of FASN inhibition with human prostate cancer cell lines, to provide the treatment strategy of FASN-targeted therapy. We revealed that tumor uptake of radiolabeled acetate reflected the FASN expression levels and sensitivity to FASN-targeted therapy with orlistat in vitro and in vivo. FASN-targeted therapy was noticeably effective against tumors with high FASN expression, which was indicated by high acetate uptake. To examine mechanisms, we established FASN knockdown prostate cancer cells by transduction of short-hairpin RNA against FASN and investigated the characteristics by analyses on morphology and cell behavior and microarray-based gene expression profiling. FASN inhibition not only suppressed cell proliferation but prevented pseudopodia formation and suppressed cell adhesion, migration, and invasion. FASN inhibition also suppressed genes involved in production of intracellular second messenger arachidonic acid and androgen hormones, both of which promote tumor progression. Collectively, our data demonstrated that uptake of radiolabeled acetate is a useful predictor of FASN-targeted therapy outcome. This suggests that [1-(11)C]acetate positron emission tomography (PET) could be a powerful tool to accomplish personalized FASN-targeted therapy by non-invasive visualization of tumor acetate uptake and selection of responsive tumors. FASN-targeted therapy could be an effective treatment to suppress multiple steps related to tumor progression in prostate cancers selected by [1-(11)C]acetate PET.

Up-regulation of USP2a and FASN in gliomas correlates strongly with glioma grade

Gliomas are the most common neoplasms in the central nervous system. The lack of efficacy of glioma therapies necessitates in-depth studies of glioma pathology, especially of the underlying molecular mechanisms that transform normal glial cells into tumor cells. Here we report that a deubiquitinating enzyme, ubiquitin-specific protease 2a (USP2a), and its substrate, fatty acid synthase (FASN), are over-expressed in glioma tissue. Using real-time quantitative polymerase chain reaction (PCR), Western blot and immunohistochemistry, we examined the expression and cellular distribution of USP2a and FASN in human glioma tissues. The expression patterns of USP2a and FASN correlated with the pathologic and clinical characteristics of the patients. Real-time PCR analysis showed that the expression levels of USP2a and its substrate FASN were higher in high-grade (World Health Organization [WHO] grades III and IV) glioma tissues than in low-grade (WHO grades I and II) glioma tissues. Western blot analysis indicated that the average optical densitometry ratio of USP2a and its substrate FASN in high-grade gliomas was higher than in low-grade gliomas. Moreover, statistical analysis of grade-classified glioma samples showed that the level of USP2a and FASN expression increased with the elevation of the WHO grade of glioma. USP2a protein expression was detected in the nucleus of glioma tissues and an increase in expression was significantly associated with the elevation of the WHO grade of glioma by immunohistochemistry. These findings expand our understanding of the molecular profiling of glioma and could shed light on new diagnostic criteria for gliomas.

Clinical significance and novel mechanism of action of kallikrein 6 in glioblastoma

BACKGROUND

Kallikreins have prognostic value in specific malignancies, but few studies have addressed their clinical significance to glioblastoma multiforme (GBM). Kallikrein 6 (KLK6) is of potential high relevance to GBM, since it is upregulated at sites of CNS pathology and linked to reactive astrogliosis. Here we examine the clinical value of KLK6 as a prognostic indicator of GBM patient survival and its activity in promoting resistance to cytotoxic agents.

METHODS

The association between patient survival and levels of KLK6 immunoreactivity were investigated in 60 grade IV astrocytoma tumor specimens. Levels of KLK6 RNA were also evaluated in a separate set of GBM patient tumors (n = 23). Recombinant KLK6 or enforced KLK6 overexpression in GBM cell lines was used to evaluate effects on astrocytoma cell survival.

RESULTS

A range of KLK6 expression was observed across grade IV tumors, with higher levels a poor prognostic indicator of patient survival (P = .02) even after adjusting for gender and Eastern Cooperative Oncology Group performance scores (P = .01). KLK6 reduced the sensitivity of GBM cell lines to cytotoxic agents, including staurosporine and cisplatin, and to the current standard of patient care: radiotherapy or temozolomide alone or in combination. The ability of KLK6 to promote resistance to apoptosis was dependent on activation of the thrombin receptor, protease activated receptor 1.

CONCLUSIONS

Taken together, these results indicate that elevated levels of KLK6 in GBM are likely to promote the resistance of tumor cells to cytotoxic agents and are an indicator of reduced patient postsurgical survival times.

Different fatty acid metabolism effects of (-)-epigallocatechin-3-gallate and C75 in adenocarcinoma lung cancer

Background

Fatty acid synthase (FASN) is overexpressed and hyperactivated in several human carcinomas, including lung cancer. We characterize and compare the anti-cancer effects of the FASN inhibitors C75 and (−)-epigallocatechin-3-gallate (EGCG) in a lung cancer model.

Methods

We evaluated in vitro the effects of C75 and EGCG on fatty acid metabolism (FASN and CPT enzymes), cellular proliferation, apoptosis and cell signaling (EGFR, ERK1/2, AKT and mTOR) in human A549 lung carcinoma cells. In vivo, we evaluated their anti-tumour activity and their effect on body weight in a mice model of human adenocarcinoma xenograft.

Results

C75 and EGCG had comparable effects in blocking FASN activity (96,9% and 89,3% of inhibition, respectively). In contrast, EGCG had either no significant effect in CPT activity, the rate-limiting enzyme of fatty acid β-oxidation, while C75 stimulated CPT up to 130%. Treating lung cancer cells with EGCG or C75 induced apoptosis and affected EGFR-signaling. While EGCG abolished p-EGFR, p-AKT, p-ERK1/2 and p-mTOR, C75 was less active in decreasing the levels of EGFR and p-AKT. In vivo, EGCG and C75 blocked the growth of lung cancer xenografts but C75 treatment, not EGCG, caused a marked animal weight loss.

Conclusions

In lung cancer, inhibition of FASN using EGCG can be achieved without parallel stimulation of fatty acid oxidation and this effect is related mainly to EGFR signaling pathway. EGCG reduce the growth of adenocarcinoma human lung cancer xenografts without inducing body weight loss. Taken together, EGCG may be a candidate for future pre-clinical development.

Fatty acid synthase inhibition by amentoflavone suppresses HER2/neu (erbB2) oncogene in SKBR3 human breast cancer cells

Fatty acid synthase (FASN) is a potential therapeutic target for treatment of cancer and obesity, and is highly elevated in 30% of HER2-overexpressing breast cancers. Considerable interest has developed in searching for novel FASN inhibitors as therapeutic agents in treatment of HER2-overexpressing breast cancers. Amentoflavone was found to be effective in suppressing FASN expression in HER2-positive SKBR3 cells. Pharmacological inhibition of FASN by amentoflavone specifically down-regulated HER2 protein and mRNA, and caused an up-regulation of PEA3, a transcriptional repressor of HER2. In addition, pharmacological blockade of FASN by amentoflavone preferentially decreased cell viability and induced cell death in SKBR3 cells. Palmitate reduced the cytotoxic effect of amentoflavone, as the percentage of viable cells was increased after the addition of exogenous palmitate. Amentoflavone-induced FASN inhibition inhibited the translocation of SREBP-1 in SKBR3 cells. Amentoflavone inhibited phosphorylation of AKT, mTOR, and JNK. The use of pharmacological inhibitors revealed that the modulation of AKT, mTOR, and JNK phosphorylation required synergistic amentoflavone-induced FASN inhibition and HER2 activation in SKBR3 cells. These results suggest that amentoflavone modulated FASN expression by regulation of HER2-pathways, and induced cell death to enhance chemopreventive or chemotherapeutic activity in HER2-positive breast cancers.

Tumor cell metabolism: an integral view

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

Electron microscopy morphology of the mitochondrial network in gliomas and their vascular microenvironment

Gliomas still represent a serious and discouraging brain tumor; despite of the diversity of therapeutic modalities, the prognosis for patients is still poor. Understanding the structural and functional characteristics of the vascular microenvironment in gliomas is essential for the design of future therapeutic strategies. This review describes and analyzes the electron microscopy morphology of the mitochondrial network in human gliomas and their vascular microenvironment. Heterogenous mitochondrial network alterations in glioma cells and in microvascular environment are implicated directly and indirectly in the processes linked to hypoxia-tolerant and hypoxia-sensitive cells phenotype, effects of the hypoxia-inducible factor-1α, increased expression of several glycolytic protein isoforms as well as fatty acid synthase, and survivin. The prevalent existence of partial and total cristolysis observed suggests that oxidative phosphorylation is severely compromised. A mixed therapy emerged as the most appropriate.

Novel ways to target brain tumour metabolism

INTRODUCTION

Glioblastoma remains a highly aggressive primary brain cancer with very poor prognosis. The detection of mutations in the metabolic enzyme isocitrate dehydrogenase in gliomas, has broadened our view of tumourigenic mechanisms. Together with renewed awareness of tumour-specific energy metabolism, research is pointed towards novel ways for targeting brain cancer.

AREAS COVERED

This paper reviews recent knowledge on the possible tumourigenic mechanism of mutant isocitrate dehydrogenase, and provides a detailed overview of cancer-specific metabolic enzymes associated with glycolysis and intracellular pH regulation. It also discusses available drugs that may serve as a basis for novel drug development to target metabolic transformation in gliomas.

EXPERT OPINION

Despite the fact that energy metabolism is a very basic cellular process, tumour specific alterations in key metabolic processes represent promising targets for glioma treatment. Novel therapies against gliomas, including those that target metabolic transformation, need to consider the genetic background of the individual tumours, to allow the correlation of treatment response with the underlying biological status, both in preclinical and clinical studies.

Fatty acid synthase as a novel target for meningioma therapy

High levels of fatty acid synthase (FAS) expression have been reported in hormone receptor-positive tumors, including prostate, breast, and ovarian cancers, and its inhibition reduces tumor growth in vitro and in vivo. Similar to other hormone receptor-positive tumor types, meningiomas are progesterone receptor- and estrogen receptor-immunoreactive brain tumors. To define the role of FAS in human meningioma growth control, we first analyzed the FAS expression using a tissue microarray containing 38 meningiomas and showed increased FAS expression in 70% of atypical WHO grade II and anaplastic WHO grade III meningiomas compared with 10% of benign WHO grade I tumors. We next confirmed this finding by real-time PCR and Western blotting. Second, we demonstrated that treatment with the FAS inhibitor, cerulenin (Cer), significantly decreased meningioma cell survival in vitro. Third, we showed that Cer treatment reduced FAS expression by modulating Akt phosphorylation (activation). Fourth, we demonstrated that Cer treatment of mice bearing meningioma xenografts resulted in significantly reduced tumor volumes associated with increased meningioma cell death. Collectively, our data suggest that the increased FAS expression in human meningiomas represents a novel therapeutic target for the treatment of unresectable or malignant meningioma.

Acyl-CoA synthetase VL3 knockdown inhibits human glioma cell proliferation and tumorigenicity

The contribution of lipid metabolic pathways to malignancy is poorly understood. Expression of the fatty acyl-CoA synthetase ACSVL3 was found to be markedly elevated in clinical malignant glioma specimens but nearly undetectable in normal glia. ACSVL3 levels correlated with the malignant behavior of human glioma cell lines and glioma cells propagated as xenografts. ACSVL3 expression was induced by the activation of oncogenic receptor tyrosine kinases (RTK) c-Met and epidermal growth factor receptor. Inhibiting c-Met activation with neutralizing anti-hepatocyte growth factor monoclonal antibodies reduced ACSVL3 expression concurrent with tumor growth inhibition in vivo. ACSVL3 expression knockdown using RNA interference, which decreased long-chain fatty acid activation, inhibited anchorage-dependent and anchorage-independent glioma cell growth by approximately 70% and approximately 90%, respectively. ACSVL3-depleted cells were less tumorigenic than control cells, and subcutaneous xenografts grew approximately 60% slower than control tumors. Orthotopic xenografts produced by ACSVL3-depleted cells were 82% to 86% smaller than control xenografts. ACSVL3 knockdown disrupted Akt function as evidenced by RTK-induced transient decreases in total and phosphorylated Akt, as well as glycogen synthase kinase 3beta, via a caspase-dependent mechanism. Expressing constitutively active myr-Akt rescued cells from the anchorage-dependent and anchorage-independent growth inhibitory effects of ACSVL3 depletion. These studies show that ACSVL3 maintains oncogenic properties of malignant glioma cells via a mechanism that involves, in part, the regulation of Akt function.

Novel Inhibitors of Fatty Acid Synthase with Anticancer Activity

PURPOSE: Fatty acid synthase (FASN) is overexpressed in human breast carcinoma. The natural polyphenol (-)-epigallocatechin-3-gallate blocks in vitro FASN activity and leads to apoptosis in breast cancer cells without any effects on carnitine palmitoyltransferase-1 (CPT-1) activity, and in vivo, does not decrease body weight. We synthesized a panel of new polyphenolic compounds and tested their effects on breast cancer models. EXPERIMENTAL DESIGN: We evaluated the in vitro effects of the compounds on breast cancer cell growth (SK-Br3, MCF-7, and MDA-MB-231), apoptosis [as assessed by cleavage of poly(ADP-ribose) polymerase], cell signaling (HER2, ERK1/2, and AKT), and fatty acid metabolism enzymes (FASN and CPT-1). In vivo, we have evaluated their antitumor activity and their effect on body weight in a mice model of BT474 breast cancer cells. RESULTS: Two compounds potently inhibited FASN activity and showed high cytotoxicity. Moreover, the compounds induced apoptosis and caused a marked decrease in the active forms of HER2, AKT, and ERK1/2 proteins. Interestingly, the compounds did not stimulate CPT-1 activity in vitro. We show evidence that one of the FASN inhibitors blocked the growth of BT474 breast cancer xenografts and did not induce weight loss in vivo. CONCLUSIONS: The synthesized polyphenolic compounds represent a novel class of FASN inhibitors, with in vitro and in vivo anticancer activity, that do not exhibit cross-activation of beta-oxidation and do not induce weight loss in animals. One of the compounds blocked the growth of breast cancer xenografts. These FASN inhibitors may represent new agents for breast cancer treatment. (Clin Cancer Res 2009;15(24):7608-15).

Trophoblastic neoplasms express fatty acid synthase, which may be a therapeutic target via its inhibitor C93

Fatty acid synthase (FASN) is an emerging tumor-associated marker and a promising antitumor therapeutic target. In this study, we analyzed the expression of FASN in normal and molar placentas, as well as gestational trophoblastic neoplasia, and assessed the effects of a new FASN inhibitor, C93, on cellular proliferation and apoptosis in choriocarcinoma cells. Using a FASN-specific monoclonal antibody, we found that FASN immunoreactivity was detected in the cytotrophoblast and intermediate (extravillous) trophoblast of normal and molar placentas, as well as in placental site nodules. All choriocarcinomas (n = 33), 90% of epithelioid trophoblastic tumors (n = 20), and 60% of placental site trophoblastic tumors (n = 10) exhibited FASN positivity. FASN expression was further confirmed in vitro by Western blot and real-time PCR. Treatment of JEG3 and JAR cells with C93 induced significant apoptosis through the caspase-3/caspase-9/poly(ADP)ribose polymerase pathway. Cell cycle progression was not affected by the inhibitor. In summary, the data indicate that FASN is expressed in the majority of gestational trophoblastic neoplasias, and is essential for choriocarcinoma cells to survive and escape from apoptosis. FASN inhibitors such as C93 warrant further investigation as targeted therapeutic agents for metastatic and chemoresistant gestational trophoblastic neoplasia.

Cytotoxic activities of 9,11-dehydroergosterol peroxide and ergosterol peroxide from the fermentation mycelia of ganoderma lucidum cultivated in the medium containing leguminous plants on Hep 3B cells

The objective of this study was to investigate the cytotoxicity of the ethanolic extract of mycelia from Ganoderma lucidum (EMG) cultivated in a medium containing leguminous plants Glycine max (L.) Merr. and Astragalus membranaceus on human hepatocellular carcinoma cells (Hep 3B) and to isolate the active components from EMG. The results indicated that EMG induced cytotoxicity in a dose- and time-dependent manner, and the cells treated with EMG for 24, 48, and 72 h had IC(50) values of 156.8, 89.9, and 70.1 microg/mL, respectively. Furthermore, EMG was fractionated into seven fractions (F1-F7). We found that F5 and F6 had higher growth inhibitory effects on Hep 3B cells than the other fractions, and F6 possessed enough amounts (about 2.1 g) to carry out a more detailed study. F6 caused a sub-G1 peak rise and DNA fragmentation in Hep 3B cells and was further separated by high-performance liquid chromatography to obtain two active compounds, 9,11-dehydroergosterol peroxide [9(11)-DHEP] (compound 1) and ergosterol peroxide (EP) (compound 2). The IC(50) values of 9(11)-DHEP and EP based on the cell viability of Hep 3B were 16.7 and 19.4 microg/mL, respectively.

[Fatty acid synthase: a new anti-tumor target]

Fatty acid synthase (FASN), an enzyme capable of de novo fatty acid synthesis, is highly expressed and activated in most human carcinomas. FASN is associated with poor prognosis in prostate and breast cancer and its inhibition is selectively cytotoxic to human cancer cells. Thus, FASN and fatty acid metabolism have become an important focus for the diagnostic and treatment of cancer. In this sense, there is an increasing interest in identifying and developing new antitumor compounds that inhibit FASN.

In vitro screening for the tumoricidal properties of international medicinal herbs

There is growing use of anticancer complementary and alternative medicines (CAMs) worldwide. The purpose of the current study is to assess a sizeable variety of natural and plant sources of diverse origin, to ascertain prospective research directives for cancer treatment and potential new chemotherapy drug sources. In this study, 374 natural extracts (10 microg/mL-5 mg/mL) were evaluated for dose-dependent tumoricidal effects using immortal neuroblastoma of spontaneous malignant origin. The findings indicate no pattern of tumoricidal effects by diverse plants with similar families/genus under the classes Pinopsida, Equisetopsida, Lycopodiosida, Filicosida, Liliopsida Monocotyledons or Magnoliopsida Dicotyledons. The results indicate that many of the most commonly used CAMs exhibited relatively weak tumoricidal effects including cats claw, astragalus, ginseng, echinacea, mistletoe, milk thistle, slippery elm, cayenne, chamomile, don quai, meadowsweet, motherwort and shepherd's purse. The data demonstrate that the most potent plant extracts were randomly dispersed within the plantae kingdom (LC(50) = 31-490 microg/mL) in order of the lowest LC(50) Dioscorea villosa (Dioscoreaceae) > Sanguinaria canadensis (Papaveraceae) > Dipsacus asper (Dipsacaceae) > Populus balsamifera (Salicaceae) > Boswellia carteri (Burseraceae) > Cyamopsis psoralioides (Fabaceae) > Rhamnus cathartica (Rhamnaceae) > Larrea tridentate (Zygophyllaceae) > Dichroa febrifuga (Hydrangeaceae) > Batschia canescens (Boraginaceae) > Kochia scoparia (Chenopodiaceae) > Solanum xanthocarpum (Solanaceae) > Opoponax chironium (Umbelliferae) > Caulophyllum thalictroides (Berberidaceae) > Dryopteris crassirhizoma (Dryopteridaceae) > Garcinia cambogia (Clusiaceae) > Vitex agnus-castus (Verbenaceae) > Calamus draco (Arecaceae). These findings show tumoricidal effect by extracts of wild yam root, bloodroot, teasel root, bakuchi seed, dichroa root, kanta kari, garcinia fruit, mace, dragons blood and the biblically referenced herbs: balm of gilead bud, frankincense and myrrh gum.

Fatty acid synthase activity in tumor cells

While normal tissues are tightly regulated by nutrition and a carefully balanced system of glycolysis and fatty acid synthesis, tumor cells are under significant evolutionary pressure to bypass many of the checks and balances afforded normally. Cancer cells have high energy expenditure from heightened proliferation and metabolism and often show increased lipogenesis. Fatty acid synthase (FASN), the enzyme responsible for catalyzing the ultimate steps of fatty acid synthesis in cells, is expressed at high levels in tumor cells and is mostly absent in corresponding normal cells. Because of the unique expression profile of FASN, there is considerable interest not only in understanding its contribution to tumor cell growth and proliferation, but also in developing inhibitors that target FASN specifically as an anti-tumor modality. Pharmacological blockade of FASN activity has identified a pleiotropic role for FASN in mediating aspects of proliferation, growth and survival. As a result, a clearer understanding of the role of FASN in tumor cells has been developed.

Loss of heterozygosity of 17p13, with possible involvement of ACADVL and ALOX15B, in the pathogenesis of adrenocortical tumors

OBJECTIVE

To determine the minimal common region of loss on 17p13 in a cohort of adrenocortical carcinomas (ACCs) (defined by a Weiss score > or =3) and adrenocortical adenomas (ACAs) (defined by a Weiss score <3) and subsequently to assess 3 genes in this region that could be involved in adrenocortical tumorigenesis.

SUMMARY BACKGROUND DATA

Loss of heterozygosity (LOH) of 17p13 has been demonstrated to occur more frequently in ACCs compared with ACAs.

METHODS

Using 12 microsatellite markers across 17p13, LOH analysis was performed on 37 paired blood and adrenocortical tumor samples (23 ACC and 14 ACA samples) to determine the minimal common region of loss for ACCs and ACAs. From this minimal region of loss, 3 genes were selected for quantitative real time reverse transcription polymerase chain reaction analysis on 20 ACCs and 30 ACAs.

RESULTS

LOH at 17p13 was found in 74% of ACCs compared with 14% of ACAs. There was a 10.4-Mb common minimal region of loss in ACCs whereas no minimal region of loss in ACAs could be demonstrated. Expression of Acyl coenzyme-A dehydrogenase very long chain (ACADVL) and Arachidonate 15-lipoxygenase second type (ALOX15B) was significantly down-regulated in ACCs compared with ACAs whereas there was no difference in expression of Potassium channel tetramerization domain containing 11 (KCTD11) in ACCs and ACAs.

CONCLUSIONS

We demonstrated a minimal common region of loss of 10.4-Mb on 17p13 in ACCs and within this region, we found that ACADVL and ALOX15B expression are good discriminators between ACCs and ACAs.

Fatty acid synthase and the lipogenic phenotype in cancer pathogenesis

There is a renewed interest in the ultimate role of fatty acid synthase (FASN)--a key lipogenic enzyme catalysing the terminal steps in the de novo biogenesis of fatty acids--in cancer pathogenesis. Tumour-associated FASN, by conferring growth and survival advantages rather than functioning as an anabolic energy-storage pathway, appears to necessarily accompany the natural history of most human cancers. A recent identification of cross-talk between FASN and well-established cancer-controlling networks begins to delineate the oncogenic nature of FASN-driven lipogenesis. FASN, a nearly-universal druggable target in many human carcinomas and their precursor lesions, offers new therapeutic opportunities for metabolically treating and preventing cancer.

Fatty acid metabolism in breast cancer cells: differential inhibitory effects of epigallocatechin gallate (EGCG) and C75

Endogenous fatty acid metabolism is crucial to maintain the cancer cell malignant phenotype. Lipogenesis is regulated by the enzyme fatty acid synthase (FASN); and breakdown of fatty acids is regulated by carnitine palmitoyltransferase-1 (CPT-I). FASN is highly expressed in breast cancer and most common human carcinomas. Several compounds can inhibit FASN, although the degree of specificity of this inhibition has not been addressed. We have tested the effects of C75 and (-)-epigallocatechin-3-gallate (EGCG) on fatty acid metabolism pathways, cellular proliferation, induction of apoptosis and cell signalling in human breast cancer cells. Our results show that C75 and EGCG had comparable effects in blocking FASN activity. Treating cancer cells with EGCG or C75 induced apoptosis and caused a decrease in the active forms of oncoprotein HER2, AKT and ERK1/2 to a similar degree. We observed, in contrast, marked differential effects between C75 and EGCG on the fatty acid oxidation pathway. While EGCG had either no effect or a moderate reduction in CPT-I activity, C75 stimulated CPT-I activity (up to 129%), even in presence of inhibitory levels of malonyl-CoA, a potent inhibitor of the CPT-I enzyme. Taken together, these findings indicate that pharmacological inhibition of FASN occurs uncoupled from the stimulation of CPT-I with EGCG but not with C75, suggesting that EGCG might be free of the CPT-I related in vivo weight-loss that has been associated with C75. Our results establish EGCG as a potent and specific inhibitor of fatty acid synthesis (FASN), which may hold promise as a target-directed anti-cancer drug.

Fatty acid synthase inhibitors cerulenin and C75 retard growth and induce caspase-dependent apoptosis in human melanoma A-375 cells

Fatty acid synthase (FAS) has been shown previously to be highly expressed in breast and prostate carcinomas, but has low expression level in normal tissues. We also found in this study that FAS was expressed in a number of cancer cell lines of different histotypes. The growth-inhibitory effects of FAS inhibitors cerulenin and C75 were then investigated on these cancer cell lines, particularly the human melanoma A-375. MTT assay revealed that the cancer cell proliferation and viability was reduced dose- and time-dependently by 20.8%-87.1% of the control levels after 24 and 48 h of treatment with 20-160 microM of the inhibitor. Immunoblotting studies showed that both cerulenin and C75 induced poly(ADP-ribose) polymerase (PARP) cleavage in the melanoma cells dose-dependently. Procaspase-3 was also found to be processed into the active and smaller 17 and 19 kDa subunits, and administration of pan-caspase inhibitor Z-VAD-FMK completely rescued the cells from PARP cleavage. This indicated that the cerulenin- and C75-induced apoptosis involved caspase activation. The proapoptotic effects of the FAS inhibitors were further confirmed using confocal microscopy with annexin-V FITC and propidium iodide staining. DNA flow cytometric studies demonstrated that the FAS inhibitors accumulated G2/M cells preceding the elevation of sub G1 or apoptotic cells with fragmented DNA. The induced cell cycle arrest and apoptosis were associated with elevation of p21 and depletion of Bcl-xL and Mcl-1, respectively. Results from this study suggest that FAS inhibitors retard growth of melanoma A-375 cells, involving activation of caspase-dependent apoptosis.