Differential gene expression profiling in human brain tumors

Directional preference for glioblastoma cancer cell membrane encapsulated nanoparticle population: A probabilistic approach for cancer therapeutics

Background

Selective cancer cell recognition is the most challenging objective in the targeted delivery of anti-cancer agents. Extruded specific cancer cell membrane coated nanoparticles, exploiting the potential of homotypic binding along with certain protein-receptor interactions, have recently proven to be the method of choice for targeted delivery of anti-cancer drugs. Prediction of the selective targeting efficiency of the cancer cell membrane encapsulated nanoparticles (CCMEN) is the most critical aspect in selecting this strategy as a method of delivery.

Materials and methods

A probabilistic model based on binding scores and differential expression levels of Glioblastoma cancer cells (GCC) membrane proteins (factors and receptors) was implemented on python 3.9.1. Conditional binding efficiency (CBE) was derived for each combination of protein involved in the interactions. Selective propensities and Odds ratios in favour of cancer cells interactions were determined for all the possible combination of surface proteins for ‘k’ degree of interaction. The model was experimentally validated by two types of Test cultures.

Results

Several Glioblastoma cell surface antigens were identified from literature and databases. Those were screened based on the relevance, availability of expression levels and crystal structure in public databases. High priority eleven surface antigens were selected for probabilistic modelling. A new term, Break-even point (BEP) was defined as a characteristic of the typical cancer cell membrane encapsulated delivery agents. The model predictions lie within ±7% of the experimentally observed values for both experimental test culture types.

Conclusion

The implemented probabilistic model efficiently predicted the directional preference of the exposed nanoparticle coated with cancer cell membrane (in this case GCC membrane). This model, however, is developed and validated for glioblastoma, can be easily tailored for any type of cancer involving CCMEN as delivery agents for potential cancer immunotherapy. This probabilistic model would help in the development of future cancer immunotherapeutic with greater specificity.

Ion Channels in Gliomas-From Molecular Basis to Treatment

Ion channels provide the basis for the nervous system's intrinsic electrical activity. Neuronal excitability is a characteristic property of neurons and is critical for all functions of the nervous system. Glia cells fulfill essential supportive roles, but unlike neurons, they also retain the ability to divide. This can lead to uncontrolled growth and the formation of gliomas. Ion channels are involved in the unique biology of gliomas pertaining to peritumoral pathology and seizures, diffuse invasion, and treatment resistance. The emerging picture shows ion channels in the brain at the crossroads of neurophysiology and fundamental pathophysiological processes of specific cancer behaviors as reflected by uncontrolled proliferation, infiltration, resistance to apoptosis, metabolism, and angiogenesis. Ion channels are highly druggable, making them an enticing therapeutic target. Targeting ion channels in difficult-to-treat brain tumors such as gliomas requires an understanding of their extremely heterogenous tumor microenvironment and highly diverse molecular profiles, both representing major causes of recurrence and treatment resistance. In this review, we survey the current knowledge on ion channels with oncogenic behavior within the heterogeneous group of gliomas, review ion channel gene expression as genomic biomarkers for glioma prognosis and provide an update on therapeutic perspectives for repurposed and novel ion channel inhibitors and electrotherapy.

Aquaporins in Nervous System

Aquaporins (AQPs) mediate water flux between the four distinct water compartments in the central nervous system (CNS). In the present chapter, we mainly focus on the expression and function of the nine AQPs expressed in the CNS, which include five members of aquaporin subfamily: AQP1, AQP4, AQP5, AQP6, and AQP8; three members of aquaglyceroporin subfamily: AQP3, AQP7, and AQP9; and one member of superaquaporin subfamily: AQP11. In addition, AQP1, AQP2, and AQP4 expressed in the peripheral nervous system are also reviewed. AQP4, the predominant water channel in the CNS, is involved both in the astrocyte swelling of cytotoxic edema and the resolution of vasogenic edema and is of pivotal importance in the pathology of brain disorders such as neuromyelitis optica, brain tumors, and neurodegenerative disorders. Moreover, AQP4 has been demonstrated as a functional regulator of recently discovered glymphatic system that is a main contributor to clearance of toxic macromolecule from the brain. Other AQPs are also involved in a variety of important physiological and pathological process in the brain. It has been suggested that AQPs could represent an important target in treatment of brain disorders like cerebral edema. Future investigations are necessary to elucidate the pathological significance of AQPs in the CNS.

Nicotinamide N-Methyltransferase as Promising Tool for Management of Gastrointestinal Neoplasms

Gastrointestinal (GI) neoplasms include esophageal, gastric, colorectal, hepatic, and pancreatic cancers. They are characterized by asymptomatic behavior, being responsible for diagnostic delay. Substantial refractoriness to chemo- and radiotherapy, exhibited by late-stage tumors, contribute to determine poor patient outcome. Therefore, it is of outmost importance to identify new molecular targets for the development of effective therapeutic strategies. In this study, we focused on the enzyme nicotinamide N-methyltransferase (NNMT), which catalyzes the N-methylation reaction of nicotinamide and whose overexpression has been reported in numerous neoplasms, including GI cancers. The aim of this review was to report data illustrating NNMT involvement in these tumors, highlighting its contribution to tumor cell phenotype. Cited works clearly demonstrate the interesting potential use of enzyme level determination for both diagnostic and prognostic purposes. NNMT was also found to positively affect cell viability, proliferation, migration, and invasiveness, contributing to sustain in vitro and in vivo tumor growth and metastatic spread. Moreover, enzyme upregulation featuring tumor cells was significantly associated with enhancement of resistance to treatment with chemotherapeutic drugs. Taken together, these results strongly suggest the possibility to target NNMT for setup of molecular-based strategies to effectively treat GI cancers.

NNMT contributes to high metastasis of triple negative breast cancer by enhancing PP2A/MEK/ERK/c-Jun/ABCA1 pathway mediated membrane fluidity

Elucidating the mechanism for high metastasis capacity of triple negative breast cancers (TNBC) is crucial to improve treatment outcomes of TNBC. We have recently reported that nicotinamide N-methyltransferase (NNMT) is overexpressed in breast cancer, especially in TNBC, and predicts poor survival of patients undergoing chemotherapy. Here, we aimed to determine the function and mechanism of NNMT on metastasis of TNBC. Additionally, analysis of public datasets indicated that NNMT is involved in cholesterol metabolism. In vitro, NNMT overexpression promoted migration and invasion of TNBCs by reducing cholesterol levels in the cytoplasm and cell membrane. Mechanistically, NNMT activated MEK/ERK/c-Jun/ABCA1 pathway by repressing protein phosphatase 2A (PP2A) activity leading to cholesterol efflux and membrane fluidity enhancement, thereby promoting the epithelial-mesenchymal transition (EMT) of TNBCs. In vivo, the metastasis capacity of TNBCs was weakened by targeting NNMT. Collectively, our findings suggest a new molecular mechanism involving NNMT in metastasis and poor survival of TNBC mediated by PP2A and affecting cholesterol metabolism.

The Water Transport System in Astrocytes–Aquaporins

Highlights

(AQPs) are transmembrane proteins responsible for fast water movement across cell membranes, including those of astrocytes.

The expression and subcellular localization of AQPs in astrocytes are highly dynamic under physiological and pathological conditions.

Besides their primary function in water homeostasis, AQPs participate in many ancillary functions including glutamate clearance in tripartite synapses and cell migration.

Abstract

Astrocytes have distinctive morphological and functional characteristics, and are found throughout the central nervous system. Astrocytes are now known to be far more than just housekeeping cells in the brain. Their functions include contributing to the formation of the blood–brain barrier, physically and metabolically supporting and communicating with neurons, regulating the formation and functions of synapses, and maintaining water homeostasis and the microenvironment in the brain. Aquaporins (AQPs) are transmembrane proteins responsible for fast water movement across cell membranes. Various subtypes of AQPs (AQP1, AQP3, AQP4, AQP5, AQP8 and AQP9) have been reported to be expressed in astrocytes, and the expressions and subcellular localizations of AQPs in astrocytes are highly correlated with both their physiological and pathophysiological functions. This review describes and summarizes the recent advances in our understanding of astrocytes and AQPs in regard to controlling water homeostasis in the brain. Findings regarding the features of different AQP subtypes, such as their expression, subcellular localization, physiological functions, and the pathophysiological roles of astrocytes are presented, with brain edema and glioma serving as two representative AQP-associated pathological conditions. The aim is to provide a better insight into the elaborate “water distribution” system in cells, exemplified by astrocytes, under normal and pathological conditions.

Transcriptomic profiling of nonneoplastic cortical tissues reveals epileptogenic mechanisms in dysembryoplastic neuroepithelial tumors

Low-grade dysembryoplastic neuroepithelial tumors (DNTs) are a frequent cause of drug-refractory epilepsy. Molecular mechanisms underlying seizure generation in these tumors are poorly understood. This study was conducted to identify altered genes in nonneoplastic epileptogenic cortical tissues (ECTs) resected from DNT patients during electrocorticography (ECoG)-guided surgery. RNA sequencing (RNAseq) was used to determine the differentially expressed genes (DEGs) in these high-spiking ECTs compared to non-epileptic controls. A total of 477 DEGs (180 upregulated; 297 downregulated) were observed in the ECTs compared to non-epileptic controls. Gene ontology analysis revealed enrichment of genes belonging to the following Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways: (i) glutamatergic synapse; (ii) nitrogen metabolism; (iii) transcriptional misregulation in cancer; and (iv) protein digestion and absorption. The glutamatergic synapse pathway was enriched by DEGs such as GRM4, SLC1A6, GRIN2C, GRM2, GRM5, GRIN3A, and GRIN2B. Enhanced glutamatergic activity was observed in the pyramidal neurons of ECTs, which could be attributed to altered synaptic transmission in these tissues compared to non-epileptic controls. Besides glutamatergic synapse, altered expression of other genes such as GABRB1 (synapse formation), SLIT2 (axonal growth), and PROKR2 (neuron migration) could be linked to epileptogenesis in ECTs. Also, upregulation of GABRA6 gene in ECTs could underlie benzodiazepine resistance in these patients. Neural cell-type-specific gene set enrichment analysis (GSEA) revealed transcriptome of ECTs to be predominantly contributed by microglia and neurons. This study provides first comprehensive gene expression profiling of nonneoplastic ECTs of DNT patients and identifies genes/pathways potentially linked to epileptogenesis.

GABRB2, a key player in neuropsychiatric disorders and beyond

The GABA receptors represent the main inhibitory system in the central nervous system that ensure synaptogenesis, neurogenesis, and the regulation of neuronal plasticity and learning. GABAA receptors are pentameric in structure and belong to the Cys-loop superfamily. The GABRB2 gene, located on chromosome 5q34, encodes the β2 subunit that combines with the α and γ subunits to form the major subtype of GABAA receptors, which account for 43% of all GABAA receptors in the mammalian brain. Each subunit probably consists of an extracellular N-terminal domain, four membrane-spanning segments, a large intracellular loop between TM3 and TM4, and an extracellular C-terminal domain. Alternative splicing of the RNA transcript of the GABRB2 gene gives rise at least to four long and short isoforms with dissimilar electrophysiological properties. Furthermore, GABRB2 is imprinted and subjected to epigenetic regulation and positive selection. It has been associated with schizophrenia first in Han Chinese, and subsequently validated in other populations. Gabrb2 knockout mice also exhibited schizophrenia-like behavior and neuroinflammation that were ameliorated by the antipsychotic drug risperidone. GABRB2 was also associated with other neuropsychiatric disorders including bipolar disorder, epilepsy, autism spectrum disorder, Alzheimer's disease, frontotemporal dementia, substance dependence, depression, internet gaming disorder, and premenstrual dysphoric disorder. Recently, it has been postulated that GABRB2 might be a potential marker for different cancer types. As GABRB2 has a pivotal role in the central nervous system and is increasingly recognized to contribute to human diseases, further understanding of its structure and function may expedite the generation of new therapeutic approaches.

Esterase-Sensitive Prodrugs of a Potent Bisubstrate Inhibitor of Nicotinamide N-Methyltransferase (NNMT) Display Cellular Activity

A recently discovered bisubstrate inhibitor of Nicotinamide N-methyltransferase (NNMT) was found to be highly potent in biochemical assays with a single digit nanomolar IC₅₀ value but lacking in cellular activity. We, here, report a prodrug strategy designed to translate the observed potent biochemical inhibitory activity of this inhibitor into strong cellular activity. This prodrug strategy relies on the temporary protection of the amine and carboxylic acid moieties of the highly polar amino acid side chain present in the bisubstrate inhibitor. The modification of the carboxylic acid into a range of esters in the absence or presence of a trimethyl-lock (TML) amine protecting group yielded a range of candidate prodrugs. Based on the stability in an aqueous buffer, and the confirmed esterase-dependent conversion to the parent compound, the isopropyl ester was selected as the preferred acid prodrug. The isopropyl ester and isopropyl ester-TML prodrugs exhibit improved cell permeability, which also translates to significantly enhanced cellular activity as established using assays designed to measure the enzymatic activity of NNMT in live cells.

The Utility of Nicotinamide N-Methyltransferase as a Potential Biomarker to Predict the Oncological Outcomes for Urological Cancers: An Update

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation reaction of nicotinamide, using S-adenosyl-L-methionine as the methyl donor. Enzyme overexpression has been described in many non-neoplastic diseases, as well as in a wide range of solid malignancies. This review aims to report and discuss evidence available in scientific literature, dealing with NNMT expression and the potential involvement in main urologic neoplasms, namely, renal, bladder and prostate cancers. Data illustrated in the cited studies clearly demonstrated NNMT upregulation (pathological vs. normal tissue) in association with these aforementioned tumors. In addition to this, enzyme levels were also found to correlate with key prognostic parameters and patient survival. Interestingly, NNMT overexpression also emerged in peripheral body fluids, such as blood and urine, thus leading to candidate the enzyme as promising biomarker for the early and non-invasive detection of these cancers. Examined results undoubtedly showed NNMT as having the capacity to promote cell proliferation, migration and invasiveness, as well as its potential participation in fundamental events highlighting cancer progression, metastasis and resistance to chemo- and radiotherapy. In the light of this evidence, it is reasonable to attribute to NNMT a promising role as a potential biomarker for the diagnosis and prognosis of urologic neoplasms, as well as a molecular target for effective anti-cancer treatment.

Roles of Nicotinamide N-Methyltransferase in Obesity and Type 2 Diabetes

Type 2 diabetes (T2D) is thought to be a complication of metabolic syndrome caused by disorders of energy utilization and storage and characterized by insulin resistance or deficiency of insulin secretion. Though the mechanism linking obesity to the development of T2D is complex and unintelligible, it is known that abnormal lipid metabolism and adipose tissue accumulation possibly play important roles in this process. Recently, nicotinamide N-methyltransferase (NNMT) has been emerging as a new mechanism-of-action target in treating obesity and associated T2D. Evidence has shown that NNMT is associated with obesity and T2D. NNMT inhibition or NNMT knockdown significantly increases energy expenditure, reduces body weight and white adipose mass, improves insulin sensitivity, and normalizes glucose tolerance and fasting blood glucose levels. Additionally, trials of oligonucleotide therapeutics and experiments with some small-molecule NNMT inhibitors in vitro and in preclinical animal models have validated NNMT as a promising therapeutic target to prevent or treat obesity and associated T2D. However, the exact mechanisms underlying these phenomena are not yet fully understood and clinical trials targeting NNMT have not been reported until now. Therefore, more researches are necessary to reveal the acting mechanism of NNMT in obesity and T2D and to develop therapeutics targeting NNMT.

Critical role of Aquaporin-1 and telocytes in infantile hemangioma response to propranolol beta blockade

Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is the first-line therapy for severe infantile hemangiomas (IH). Since the incidental discovery of propranolol efficacy in IH, preclinical and clinical investigations have shown evidence of adjuvant propranolol response in some malignant tumors. However, the mechanism for propranolol antitumor effect is still largely unknown, owing to the absence of a tumor model responsive to propranolol at nontoxic concentrations. Immunodeficient mice engrafted with different human tumor cell lines were treated with anti-VEGF bevacizumab to create a model sensitive to propranolol. Proteomics analysis was used to reveal propranolol-mediated protein alteration correlating with tumor growth inhibition, and Aquaporin-1 (AQP1), a water channel modulated in tumor cell migration and invasion, was identified. IH tissues and cells were then functionally investigated. Our functional protein association networks analysis and knockdown of ADRB2 and AQP1 indicated that propranolol treatment and AQP1 down-regulation trigger the same pathway, suggesting that AQP1 is a major driver of beta-blocker antitumor response. Examining AQP1 in human hemangioma samples, we found it exclusively in a perivascular layer, so far unrecognized in IH, made of telocytes (TCs). Functional in vitro studies showed that AQP1-positive TCs play a critical role in IH response to propranolol and that modulation of AQP1 in IH-TC by propranolol or shAQP1 decreases capillary-like tube formation in a Matrigel-based angiogenesis assay. We conclude that IH sensitivity to propranolol may rely, at least in part, on a cross talk between lesional vascular cells and stromal TCs.

Glutamatergic Mechanisms in Glioblastoma and Tumor-Associated Epilepsy

The progression of glioblastomas is associated with a variety of neurological impairments, such as tumor-related epileptic seizures. Seizures are not only a common comorbidity of glioblastoma but often an initial clinical symptom of this cancer entity. Both, glioblastoma and tumor-associated epilepsy are closely linked to one another through several pathophysiological mechanisms, with the neurotransmitter glutamate playing a key role. Glutamate interacts with its ionotropic and metabotropic receptors to promote both tumor progression and excitotoxicity. In this review, based on its physiological functions, our current understanding of glutamate receptors and glutamatergic signaling will be discussed in detail. Furthermore, preclinical models to study glutamatergic interactions between glioma cells and the tumor-surrounding microenvironment will be presented. Finally, current studies addressing glutamate receptors in glioma and tumor-related epilepsy will be highlighted and future approaches to interfere with the glutamatergic network are discussed.

Parenteral high‑dose ascorbate - A possible approach for the treatment of glioblastoma (Review)

For glioblastoma, the treatment with standard of care therapy comprising resection, radiation, and temozolomide results in overall survival of approximately 14-18 months after initial diagnosis. Even though several new therapy approaches are under investigation, it is difficult to achieve life prolongation and/or improvement of patient's quality of life. The aggressiveness and progression of glioblastoma is initially orchestrated by the biological complexity of its genetic phenotype and ability to respond to cancer therapy via changing its molecular patterns, thereby developing resistance. Recent clinical studies of pharmacological ascorbate have demonstrated its safety and potential efficacy in different cancer entities regarding patient's quality of life and prolongation of survival. In this review article, the actual glioblastoma treatment possibilities are summarized, the evidence for pharmacological ascorbate in glioblastoma treatment is examined and questions are posed to identify current gaps of knowledge regarding accessibility of ascorbate to the tumor area. Experiments with glioblastoma cell lines and tumor xenografts have demonstrated that high-dose ascorbate induces cytotoxicity and oxidative stress largely selectively in malignant cells compared to normal cells suggesting ascorbate as a potential therapeutic agent. Further investigations in larger cohorts and randomized placebo-controlled trials should be performed to confirm these findings as well as to improve delivery strategies to the brain, through the inherent barriers and ultimately to the malignant cells.

Development of fluorescence polarization-based competition assay for nicotinamide N-methyltransferase

Methylation-mediated pathways play important roles in the progression of various diseases. Thus, targeting methyltransferases has proven to be a promising strategy for developing novel therapies. Nicotinamide N-methyltransferase (NNMT) is a major metabolic enzyme involved in epigenetic regulation through catalysis of methyl transfer from the cofactor S-adenosyl-l-methionine onto nicotinamide and other pyridines. Accumulating evidence infers that NNMT is a novel therapeutic target for a variety of diseases such as cancer, diabetes, obesity, cardiovascular and neurodegenerative diseases. Therefore, there is an urgent need to discover potent and specific inhibitors for NNMT to assess its therapeutical potential. Herein, we reported the design and synthesis of a fluorescent probe II138, exhibiting a K_d value of 369 ± 14 nM for NNMT. We also established a fluorescence polarization (FP)-based competition assay for evaluation of NNMT inhibitors. Importantly, the unique feature of this FP competition assay is its capability to identify inhibitors that interfere with the interaction of the NNMT active site directly or allosterically. In addition, this assay performance is robust with a Z'factor of 0.76, indicating its applicability in high-throughput screening for NNMT inhibitors.

Matrix protease production, epithelial-to-mesenchymal transition marker expression and invasion of glioblastoma cells in response to osmotic or hydrostatic pressure

Both hydrostatic and osmotic pressures are altered in the tumour microenvironment. Glioblastoma (GBM) is a brain tumour with high invasiveness and poor prognosis. We hypothesized that physical and osmotic forces regulate glioblastoma (GBM) invasiveness. The osmotic pressure of GBM cell culture medium was adjusted using sodium chloride or water. Alternatively, cells were subjected to increased hydrostatic force. The proteolytic profile and epithelial–mesenchymal transition (EMT) were investigated using zymography and real-time qPCR. The EMT markers assessed were Snail-1, Snail-2, N-cadherin, Twist and vimentin. Invasion was investigated in vitro using extracellular matrix-coated Transwell inserts. In response to osmotic and mechanical pressure, GBM cell lines U87 and U251 and patient-derived neural oncospheres upregulated the expression of urokinase-type plasminogen activator (uPA) and/or matrix metalloproteinases (MMPs) as well as some of the EMT markers tested. The adherent cell lines invaded more when placed in media of increased osmolality. Therefore, GBM respond to osmotic or mechanical pressure by increasing matrix degrading enzyme production, and adopting a phenotype reminiscent of EMT. Better understanding the molecular and cellular mechanisms by which increased pressure promotes GBM invasiveness may help to develop innovative therapeutic approaches.

Meningioma Tumor Microenvironment

The tumor microenvironment consists of noncancerous cells, such as immune cells and fibroblasts, and the proteins produced by these cells as well as the extracellular matrix components in the environment around a tumor. Tumor influences the behavior of the cells present in the surrounding environment, while the cells in the tumor microenvironment modulate the evolution of the tumor. Little is known about the microenvironment of meningioma, the most common benign intracranial tumor. Here, we review the current knowledge of the tumor microenvironment of meningioma and discusses its importance in meningioma tumorigenesis as well as in the designation of novel therapeutic approaches.

AEBP1 down regulation induced cell death pathway depends on PTEN status of glioma cells

Glioblastoma (GBM) is the most common aggressive form of brain cancer with overall dismal prognosis (10–12 months) despite all current multimodal treatments. Previously we identified adipocyte enhancer binding protein 1 (AEBP1) as a differentially regulated gene in GBM. On probing the role of AEBP1 over expression in glioblastoma, we found that both cellular proliferation and survival were affected upon AEBP1 silencing in glioma cells, resulting in cell death. In the present study we report that the classical caspase pathway components are not activated in cell death induced by AEBP1 down regulation in PTEN-deficient (U87MG and U138MG) cells. PARP-1 was not cleaved but over-activated under AEBP1 down regulation which leads to the synthesis of PAR in the nucleus triggering the release of AIF from the mitochondria. Subsequently, AIF translocates to the nucleus along with MIF causing chromatinolysis. AEBP1 positively regulates PI3KinaseCβ by the binding to AE-1 binding element in the PI3KinaseCβ promoter. Loss of PI3KinaseCβ expression under AEBP1 depleted condition leads to excessive DNA damage and activation of PARP-1. Furthermore, over expression of PIK3CB (in trans) in U138MG cells prevents DNA damage in these AEBP1 depleted cells. On the contrary, AEBP1 down regulation induces caspase-dependent cell death in PTEN-proficient (LN18 and LN229) cells. Ectopic expression of wild-type PTEN in PTEN-deficient U138MG cells results in the activation of canonical caspase and Akt dependent cell death. Collectively, our findings define AEBP1 as a potential oncogenic driver in glioma, with potential implications for therapeutic intervention.

Decane-1,2-diol derivatives as potential antitumor agents for the treatment of glioblastoma

Glioblastoma remains the most common and aggressive type of malignant brain tumor among adults thus, considerable attention has been given to discovery of novel anti-tumor drugs for its treatment. This study reports the synthesis of a series of twelve novel decane-1,2-diol derivatives and evaluation of its anti-tumor activity in mammalian glioblastoma cell lines, U87 and LN229. Starting from decane-1,2-diol, several derivatives were prepared using a diversity oriented synthesis approach through which a small library composed of esters, silyl ethers, sulfonates, sulfites, sulfates, ketals, and phosphonates was built. The decane-1,2-diol ditosylated derivative, DBT, found to have higher cytotoxicity than the standard drug cisplatin, has IC₅₀ value of 52 µM in U87 and 270 µM in LN229. Migration analysis of U87 cell line treated with the DBT indicated its ability to effectively suppress proliferation during initial hours of treatment and decrease anti-proliferative property over time. Additionally, DBT was assessed for its role in apoptosis, oxidative stress and caspase 3/7 activation in U87. Interestingly, our experiments indicated that its cytotoxicity is independent of Reactive oxygen species induced caspase 3/7 activity. The compound also exhibited caspase independent apoptosis activity in U87. DBT treatment led to G1/S cell cycle arrest and apoptosis induction of glioma cell lines. In addition, we identified 1533 genes with significant changes at the transcriptional level, in response to DBT. A molecular docking study accounting for the interaction of DBT with NMDA receptor disclosed several hydrogen bonds and charged residue interactions with 17 amino acids, which might be the basis of the DBT cytotoxicity observed. We conclude that this molecule exerts its cytotoxicity via caspase 3/7 independent pathways in glioblastoma cells. Concisely, simple decane-1,2-diol derivatives might serve as scaffolds for the development of effective anti-glioblastoma agents.

Pathogenic role for macrophage migration inhibitory factor in glioblastoma and its targeting with specific inhibitors as novel tailored therapeutic approach

Macrophage Migration Inhibitory Factor (MIF) is a pro-inflammatory cytokine expressed by a variety of cell types. Although MIF has been primarily studied for its role in the pathogenesis of autoimmune diseases, it has also been shown to promote tumorigenesis and it is over expressed in various malignant tumors. MIF is able to induce angiogenesis, cell cycle progression, and to block apoptosis. As tailored therapeutic approaches for the inhibition of endogenous MIF are being developed, it is important to evaluate the role of MIF in individual neoplastic conditions that may benefit from specific MIF inhibitors. Along with this line, in this paper, we have reviewed the evidence of the involvement of MIF in the etiopathogenesis and progression of glioblastoma and the preclinical data suggesting the possible use of specific MIF inhibition as a potential novel therapeutic strategy for brain tumors.

Oxidized macrophage migration inhibitory factor is a potential new tissue marker and drug target in cancer

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine, which was shown to be upregulated in cancers and to exhibit tumor promoting properties. Unlike other cytokines, MIF is ubiquitously present in the circulation and tissue of healthy subjects. We recently described a previously unrecognized, disease-related isoform of MIF, designated oxMIF, which is present in the circulation of patients with different inflammatory diseases. In this article, we report that oxMIF is also linked to different solid tumors as it is specifically expressed in tumor tissue from patients with colorectal, pancreatic, ovarian and lung cancer. Furthermore, oxMIF can be specifically targeted by a subset of phage display-derived fully human, monoclonal anti-MIF antibodies (mAbs) that were shown to neutralize pro-tumorigenic activities of MIF in vivo. We further demonstrate that anti-oxMIF mAbs sensitize human cancer cell lines (LNCaP, PC3, A2780 and A2780ADR) to the action of cytotoxic drugs (mitoxantrone, cisplatin and doxorubicin) in vitro and in an A2780 xenograft mouse model of ovarian cancer. We conclude that oxMIF is the disease related isoform of MIF in solid tumors and a potential new diagnostic marker and drug target in cancer.

Discovery of Bisubstrate Inhibitors of Nicotinamide N-Methyltransferase (NNMT)

Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of pyridine-containing compounds using the cofactor S-5'-adenosyl-l-methionine (SAM) as the methyl group donor. Through the regulation of the levels of its substrates, cofactor, and products, NNMT plays an important role in physiology and pathophysiology. Overexpression of NNMT has been implicated in various human diseases. Potent and selective small-molecule NNMT inhibitors are valuable chemical tools for testing biological and therapeutic hypotheses. However, very few NNMT inhibitors have been reported. Here, we describe the discovery of a bisubstrate NNMT inhibitor MS2734 (6) and characterization of this inhibitor in biochemical, biophysical, kinetic, and structural studies. Importantly, we obtained the first crystal structure of human NNMT in complex with a small-molecule inhibitor. The structure of the NNMT-6 complex has unambiguously demonstrated that 6 occupied both substrate and cofactor binding sites. The findings paved the way for developing more potent and selective NNMT inhibitors in the future.

MIF Plays a Key Role in Regulating Tissue-Specific Chondro-Osteogenic Differentiation Fate of Human Cartilage Endplate Stem Cells under Hypoxia

Degenerative cartilage endplate (CEP) shows decreased chondrification and increased ossification. Cartilage endplate stem cells (CESCs), with the capacity for chondro-osteogenic differentiation, are responsible for CEP restoration. CEP is avascular and hypoxic, while the physiological hypoxia is disrupted in the degenerated CEP. Hypoxia promoted chondrogenesis but inhibited osteogenesis in CESCs. This tissue-specific differentiation fate of CESCs in response to hypoxia was physiologically significant with regard to CEP maintaining chondrification and refusing ossification. MIF, a downstream target of HIF1A, is involved in cartilage and bone metabolisms, although little is known about its regulatory role in differentiation. In CESCs, MIF was identified as a key point through which HIF1A regulated the chondro-osteogenic differentiation. Unexpectedly, unlike the traditionally recognized mode, increased nuclear-expressed MIF under hypoxia was identified to act as a transcriptional regulator by interacting with the promoter of SOX9 and RUNX2. This mode of HIF1A/MIF function may represent a target for CEP degeneration therapy.

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The hypoxic microenvironment is disrupted in degenerative CEP

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Hypoxia promotes chondrogenesis but inhibits osteogenesis in CESCs

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Hypoxia regulates chondro-osteogenesis through HIF1A/MIF pathway

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MIF acts as a transcriptional regulator under hypoxia

Clinical performance and utility of a NNMT-based urine test for bladder cancer

Background:

Bladder cancer (BC) represents the most common neoplasm of the urinary tract. Although cystoscopy and urine cytology represent the gold standard methods to monitor BC, both procedures have limitations. Therefore, the identification of reliable biomarkers for early and noninvasive detection of BC is urgently required.

Methods:

In this study, we analyzed nicotinamide N-methyltransferase (NNMT) expression in urine samples from 55 BC patients and 107 controls, using real-time polymerase chain reaction (PCR). Receiver operating characteristic (ROC) analysis was used to identify the best cutoff value to discriminate BC patients from healthy donors, and to evaluate the diagnostic accuracy of a urine-based NNMT test.

Results:

The results demonstrated that urinary NNMT expression was significantly (p<0.05) higher in BC patients. Moreover, a significant (p<0.05) inverse correlation was found between NNMT expression and histological grade. The ROC analysis revealed that a ΔCq of 13.3 was the best cutoff value, since it was associated with the highest combination of sensitivity and specificity. Moreover, the area under the curve (AUC) value was 0.913 (p<0.05), indicating the excellent diagnostic accuracy of a urine-based NNMT test.

Conclusions:

Our data indicate that NNMT is a promising biomarker that could be used to support the early and noninvasive diagnosis of BC.

Gene expression variability and the analysis of large-scale RNA-seq studies with the MDSeq

Rapidly decreasing cost of next-generation sequencing has led to the recent availability of large-scale RNA-seq data, that empowers the analysis of gene expression variability, in addition to gene expression means. In this paper, we present the MDSeq, based on the coefficient of dispersion, to provide robust and computationally efficient analysis of both gene expression means and variability on RNA-seq counts. The MDSeq utilizes a novel reparametrization of the negative binomial to provide flexible generalized linear models (GLMs) on both the mean and dispersion. We address challenges of analyzing large-scale RNA-seq data via several new developments to provide a comprehensive toolset that models technical excess zeros, identifies outliers efficiently, and evaluates differential expressions at biologically interesting levels. We evaluated performances of the MDSeq using simulated data when the ground truths are known. Results suggest that the MDSeq often outperforms current methods for the analysis of gene expression mean and variability. Moreover, the MDSeq is applied in two real RNA-seq studies, in which we identified functionally relevant genes and gene pathways. Specifically, the analysis of gene expression variability with the MDSeq on the GTEx human brain tissue data has identified pathways associated with common neurodegenerative disorders when gene expression means were conserved.

Nicotinamide N-Methyltransferase: More Than a Vitamin B3 Clearance Enzyme

Nicotinamide (NAM) N-methyltransferase (NNMT) was originally identified as the enzyme responsible for the methylation of NAM, one of the forms of vitamin B3. Methylated NAM is eventually excreted from the body. Recent evidence has expanded the role of NNMT beyond clearance of excess vitamin B3. NNMT has been implicated in the regulation of multiple metabolic pathways in tissues such as adipose and liver as well as cancer cells through the consumption of methyl donors and generation of active metabolites. This review examines recent findings regarding the function of NNMT in physiology and disease and highlights potential new avenues for therapeutic intervention. Finally, key gaps in our knowledge about this enzymatic system and future areas of investigation are discussed.

Aquaporins in Nervous System

Aquaporins (AQPs ) mediate water flux between the four distinct water compartments in the central nervous system (CNS). In the present chapter, we mainly focus on the expression and function of the 9 AQPs expressed in the CNS, which include five members of aquaporin subfamily: AQP1, AQP4, AQP5, AQP6, and AQP8; three members of aquaglyceroporin subfamily: AQP3, AQP7, and AQP9; and one member of superaquaporin subfamily: AQP11. In addition, AQP1, AQP2 and AQP4 expressed in the peripheral nervous system (PNS) are also reviewed. AQP4, the predominant water channel in the CNS, is involved both in the astrocyte swelling of cytotoxic edema and the resolution of vasogenic edema, and is of pivotal importance in the pathology of brain disorders such as neuromyelitis optica , brain tumors and Alzheimer's disease. Other AQPs are also involved in a variety of important physiological and pathological process in the brain. It has been suggested that AQPs could represent an important target in treatment of brain disorders like cerebral edema. Future investigations are necessary to elucidate the pathological significance of AQPs in the CNS.

Zinc and zinc-containing biomolecules in childhood brain tumors

Zinc ions are essential cofactors of a wide range of enzymes, transcription factors, and other regulatory proteins. Moreover, zinc is also involved in cellular signaling and enzymes inhibition. Zinc dysregulation, deficiency, over-supply, and imbalance in zinc ion transporters regulation are connected with various diseases including cancer. A zinc ion pool is maintained by two types of proteins: (i) zinc-binding proteins, which act as a buffer and intracellular donors of zinc and (ii) zinc transporters responsible for zinc fluxes into/from cells and organelles. The decreased serum zinc ion levels have been identified in patients suffering from various cancer diseases, including head and neck tumors and breast, prostate, liver, and lung cancer. On the contrary, increased zinc ion levels have been found in breast cancer and other malignant tissues. Zinc metalloproteomes of a majority of tumors including brain ones are still not yet fully understood. Current knowledge show that zinc ion levels and detection of certain zinc-containing proteins may be utilized for diagnostic and prognostic purposes. In addition, these proteins can also be promising therapeutic targets. The aim of the present work is an overview of the importance of zinc ions, zinc transporters, and zinc-containing proteins in brain tumors, which are, after leukemia, the second most common type of childhood cancer and the second leading cause of death in children after accidents.

Aquaporins and Brain Tumors

Brain primary tumors are among the most diverse and complex human cancers, and they are normally classified on the basis of the cell-type and/or the grade of malignancy (the most malignant being glioblastoma multiforme (GBM), grade IV). Glioma cells are able to migrate throughout the brain and to stimulate angiogenesis, by inducing brain capillary endothelial cell proliferation. This in turn causes loss of tight junctions and fragility of the blood–brain barrier, which becomes leaky. As a consequence, the most serious clinical complication of glioblastoma is the vasogenic brain edema. Both glioma cell migration and edema have been correlated with modification of the expression/localization of different isoforms of aquaporins (AQPs), a family of water channels, some of which are also involved in the transport of other small molecules, such as glycerol and urea. In this review, we discuss relationships among expression/localization of AQPs and brain tumors/edema, also focusing on the possible role of these molecules as both diagnostic biomarkers of cancer progression, and therapeutic targets. Finally, we will discuss the possibility that AQPs, together with other cancer promoting factors, can be exchanged among brain cells via extracellular vesicles (EVs).

Quantitative Phosphoproteomics Reveals Wee1 Kinase as a Therapeutic Target in a Model of Proneural Glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332-43. ©2016 AACR.

Quantitative Phosphoproteomics Reveals Wee1 Kinase as a Therapeutic Target in a Model of Proneural Glioblastoma

Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332-43. ©2016 AACR.

MIF Maintains the Tumorigenic Capacity of Brain Tumor-Initiating Cells by Directly Inhibiting p53

Tumor-initiating cells thought to drive brain cancer are embedded in a complex heterogeneous histology. In this study, we isolated primary cells from 21 human brain tumor specimens to establish cell lines with high tumorigenic potential and to identify the molecules enabling this capability. The morphology, sphere-forming ability upon expansion, and differentiation potential of all cell lines were indistinguishable in vitro However, testing for tumorigenicity revealed two distinct cell types, brain tumor-initiating cells (BTIC) and non-BTIC. We found that macrophage migration inhibitory factor (MIF) was highly expressed in BTIC compared with non-BTIC. MIF bound directly to both wild-type and mutant p53 but regulated p53-dependent cell growth by different mechanisms, depending on glioma cell line and p53 status. MIF physically interacted with wild-type p53 in the nucleus and inhibited its transcription-dependent functions. In contrast, MIF bound to mutant p53 in the cytoplasm and abrogated transcription-independent induction of apoptosis. Furthermore, MIF knockdown inhibited BTIC-induced tumor formation in a mouse xenograft model, leading to increased overall survival. Collectively, our findings suggest that MIF regulates BTIC function through direct, intracellular inhibition of p53, shedding light on the molecular mechanisms underlying the tumorigenicity of certain malignant brain cells. Cancer Res; 76(9); 2813-23. ©2016 AACR.

Expression of aquaporin water channels in human urothelial carcinoma: correlation of AQP3 expression with tumour grade and stage

PURPOSE

To study the expression, localization and potential clinical significance of aquaporin water channels both in well-established urothelial cancer (UC) cell lines and in human bladder carcinoma specimens of different stages and grades and to discuss the clinical relevance of the findings.

METHODS

AQP transcript and protein expression by RT4, RT112 and T24 UC cell lines was investigated using reverse transcriptase polymerase chain reaction and immunofluorescence labelling. Immunohistochemistry (IHC) was used to assess AQP protein expression in 94 UC specimens of various grades and stages.

RESULTS

AQP3 and 9 transcripts were expressed in low-grade RT4 and RT112, but not in high-grade T24 cells. By contrast, AQP4 mRNA was absent in RT4, but expressed by RT112 and T24. Transcripts for AQP7 and 11 were detected in all three UC cell lines. Immunofluorescence microscopy confirmed the expression of AQP3, 4 and 7 at the protein level. By IHC, AQP3 was shown to be intensely expressed by 86 %, 66 % and 33 % of specimens of stage pTa, pT1 and pT2 tumours, respectively (p < 0.001). Whereas 100 % of G1 tumours were positive, only 73 % and 55 % of G2 and G3 tumours were found to express AQP3 (p = 0.004).

CONCLUSIONS

This is the first study to demonstrate that several AQPs are expressed in UC. Our results indicate that there is a correlation between AQP3 protein expression and tumour stage and grade, with AQP3 expression being reduced or lost in tumours of higher grade and stage. Taken together with the available evidence from other studies, we conclude that AQPs may play a role in the progression of UC and, in particular, that this could be of prognostic value.

25 Years On: A Retrospective on Migration Inhibitory Factor in Tumor Angiogenesis

Twenty-five years ago marked the publication of the first report describing a functional contribution by the cytokine, macrophage migration inhibitory factor (MIF), to tumor-associated angiogenesis and growth. Since first appearing, this report has been cited 304 times (as of this writing), underscoring not only the importance of this landmark study but also the importance of MIF in tumor neovascularization. Perhaps more importantly, this first link between MIF and stromal cell-dependent tumor angiogenesis presaged the subsequent identification of MIF in mediating protumorigenic contributions to several solid tumor stromal cell types, including monocytes, macrophages, T lymphocytes, NK cells, fibroblasts, endothelial progenitors and mesenchymal stem cells. This retrospective review will broadly evaluate both past and present literature stemming from this initial publication, with an emphasis on cellular sources, cellular effectors, signal transduction mechanisms and the clinical importance of MIF-dependent tumor vascularization.

Macrophage migration inhibitory factor-CXCR4 is the dominant chemotactic axis in human mesenchymal stem cell recruitment to tumors

Mesenchymal stromal cells (MSCs) are inherently tumor homing and can be isolated, expanded, and transduced, making them viable candidates for cell therapy. This tumor tropism has been used to deliver anticancer therapies to various tumor models. In this study, we sought to discover which molecules are the key effectors of human MSC tumor homing in vitro and using an in vivo murine model. In this study, we discover a novel role for macrophage migration inhibitory factor (MIF) as the key director of MSC migration and infiltration toward tumor cells. We have shown this major role for MIF using in vitro migration and invasion assays, in presence of different receptor inhibitors and achieving a drastic decrease in both processes using MIF inhibitor. Additionally, we demonstrate physical interaction between MIF and three receptors: CXCR2, CXCR4, and CD74. CXCR4 is the dominant receptor used by MIF in the homing tumor context, although some signaling is observed through CXCR2. We demonstrate downstream activation of the MAPK pathway necessary for tumor homing. Importantly, we show that knockdown of either CXCR4 or MIF abrogates MSC homing to tumors in an in vivo pulmonary metastasis model, confirming the in vitro two-dimensional and three-dimensional assays. This improved understanding of MSC tumor tropism will further enable development of novel cellular therapies for cancers.

Brain tumors: Special characters for research and banking

A brain tumor is an intracranial neoplasm within the brain or in the central spinal canal. Primary malignant brain tumors affect about 200,000 people worldwide every year. Brain cells have special characters. Due to the specific properties of brain tumors, including epidemiology, growth, and division, investigation of brain tumors and the interpretation of results is not simple. Research to identify the genetic alterations of human tumors improves our knowledge of tumor biology, genetic interactions, progression, and preclinical therapeutic assessment. Obtaining data for prevention, diagnosis, and therapy requires sufficient samples, and brain tumors have a wide range. As a result, establishing the bank of brain tumors is very important and essential.

Nicotinamide N-methyltransferase is overexpressed in prostate cancer and correlates with prolonged progression-free and overall survival times

Nicotinamide N -methyltransferase (NNMT) has been identified to be associated with tumorigenesis and the malignant transformation of numerous types of cancer. The aim of the present study was to explore the expression and prognostic significance of NNMT in prostate cancer (PCa). Immunohistochemical NNMT expression was examined in 26 cases of benign prostate hyperplasia (BPH), 18 cases of high-grade prostatic intraepithelial neoplasia (HGPIN) and 120 cases of PCa. While rarely expressed in BPH (8/26 cases; 30.8%), NNMT was found to be significantly upregulated in HGPIN (15/18 cases; 83.3%) and PCa (77/120 cases; 64.2%). Clinicopathological analysis revealed that NNMT expression was negatively correlated with Gleason score (P<0.001). Furthermore, Kaplan-Meier survival curves revealed that high NNMT expression was associated with prolonged progression-free survival (PFS) and overall survival (OS) times in patients with advanced PCa. Multivariate analysis showed that NNMT was an independent prognostic marker of PFS and OS in patients with advanced PCa. The results of the present study suggested that NNMT may contribute to the development of PCa and may potentially be a favorable prognostic marker for the survival of patients with advanced PCa.

miR-874 Inhibits cell proliferation, migration and invasion through targeting aquaporin-3 in gastric cancer

BACKGROUND

Aquaporin-3 (AQP3) is a water transporting protein which plays an oncogenic role in several malignant tumors. However, its regulatory mechanism remains elusive to date. In this study, we investigated the microRNA-mediated gene repression mechanism involved in AQP3's role.

METHODS

The potential microRNAs targeting AQP3 were searched via bioinformatic methods and identified by luciferase reporter assays, microRNA RT-PCR and western blotting. The expression patterns of miR-874 and AQP3 in human gastric cancer (GC) specimens and cell lines were determined by microRNA RT-PCR and western blotting. 5-ethynyl-2'-deoxyuridine, cell migration and invasion assays and tumorigenicity in vivo were adopted to observe the effects of miR-874 depletion or ectopic miR-874 expression on GC cell phenotypes. Cell apoptosis was evaluated by FACS and TUNEL in vitro and in vivo respectively.

RESULTS

miR-874 suppressed AQP3 expression by binding to the 3'UTR of AQP3 mRNA in GC cells. miR-874 was significantly down-regulated and reversely correlated with AQP3 protein levels in clinical samples. Analysis of the clinicopathological significance showed that miR-874 and AQP3 were closely correlated with GC characteristics. Functional analyses indicated that ectopic miR-874 expression suppressed the growth, migration, invasion and tumorigenicity of GC cells, whereas miR-874 knockdown promoted these phenotypes. Down-regulation of Bcl-2, MT1-MMP, MMP-2 and MMP-9 and upregulation of caspase-3 activity and Bax were involved in miR-874 inducing cell apoptosis, and inhibiting migration and invasion.

CONCLUSIONS

These results provide a mechanism by which AQP3 is upregulated, as well as highlight the importance of miR-874 in gastric cancer development and progression.

NMDA receptors on the surface of cancer cells: target for chemotherapy?

The mammalian target of rapamycin (mTOR), a serine/threonine kinase, is a therapeutic target for many types of cancers. NMDA receptors regulate mTOR signalling activity; their inappropriate expression on several human cancer cell lines represents a potential therapeutic avenue to control dysregulated growth, division and invasiveness. Targeting these receptors with selective ligands (e.g., glycineB site ligands) may be a less toxic and more tolerable approach than administering compounds acting at the mTORC1 complex itself, such as rapamycin and its derivatives. Thus, testing glycineB site ligands in relevant in vitro and in vivo paradigms with established human cancer cells that express NMDA receptors on their surface could provide proofs of concept/principle that would encourage exploration of these and other "non-toxic" strategies. Interestingly, in some cancer models that express NMDA receptors on their surface, NMDA receptor antagonists, such as MK-801 (dizocilpine), were shown to possess anti-proliferative and anti-invasive effects, which conflict with hypotheses about promoting NMDA receptor activation as a cancer chemotherapeutic strategy. Whether NMDA receptor activation or antagonism is associated with anti-proliferative and anti-invasive effects may reflect differences between cancer cell lines in terms of the proteins associated with the NMDA receptors on their cell surfaces, which, in turn, could lead to different "downstream" effects on cascades of intracellular phosphorylations. Irrespective of whether activation or antagonism is associated with anti-proliferative and anti-invasive effects for specific types of cancer, data are emerging that support exploration of targeting NMDA receptors expressed on the surface of cancer cells as a therapeutic strategy.

Brain barriers and a subpopulation of astroglial progenitors of developing human forebrain are immunostained for the glycoprotein YKL-40

YKL-40, a glycoprotein involved in cell differentiation, has been associated with neurodevelopmental disorders, angiogenesis, neuroinflammation and glioblastomas. We evaluated YKL-40 protein distribution in the early human forebrain using double-labeling immunofluorescence and immunohistochemistry. Immunoreactivity was detected in neuroepithelial cells, radial glial end feet, leptomeningeal cells and choroid plexus epithelial cells. The subpial marginal zone was YKL-40-positive, particularly in the hippocampus, from an early beginning stage in its development. Blood vessels in the intermediate and subventricular zones showed specific YKL-40 reactivity confined to pericytes. Furthermore, a population of YKL-40-positive, small, rounded cells was identified in the ventricular and subventricular zones. Real-time quantitative RT-PCR analysis showed strong YKL-40 mRNA expression in the leptomeninges and the choroid plexuses, and weaker expression in the telencephalic wall. Immunohistochemistry revealed a differential distribution of YKL-40 across the zones of the developing telencephalic wall. We show that YKL-40 is associated with sites of the brain barrier systems and propose that it is involved in controlling local angiogenesis and access of peripheral cells to the forebrain via secretion from leptomeningeal cells, choroid plexus epithelium and pericytes. Furthermore, we suggest that the small, rounded, YKL-40-positive cells represent a subpopulation of astroglial progenitors, and that YKL-40 could be involved in the differentiation of a particular astrocytic lineage.

Systematic review of protein biomarkers of invasive behavior in glioblastoma

Glioblastoma (GBM) is an aggressive and incurable brain tumor with a grave prognosis. Recurrence is inevitable even with maximal surgical resection, in large part because GBM is a highly invasive tumor. Invasiveness also contributes to the failure of multiple cornerstones of GBM therapy, including radiotherapy, temozolomide chemotherapy, and vascular endothelial growth factor blockade. In recent years there has been significant progress in the identification of protein biomarkers of invasive phenotype in GBM. In this article, we comprehensively review the literature and survey a broad spectrum of biomarkers, including proteolytic enzymes, extracellular matrix proteins, cell adhesion molecules, neurodevelopmental factors, cell signaling and transcription factors, angiogenic effectors, metabolic proteins, membrane channels, and cytokines and chemokines. In light of the marked variation seen in outcomes in GBM patients, the systematic use of these biomarkers could be used to form a framework for better prediction, prognostication, and treatment selection, as well as the identification of molecular targets for further laboratory investigation and development of nascent, directed therapies.

Transcriptional analysis of aggressiveness and heterogeneity across grades of astrocytomas

Astrocytoma is the most common glioma, accounting for half of all primary brain and spinal cord tumors. Late detection and the aggressive nature of high-grade astrocytomas contribute to high mortality rates. Though many studies identify candidate biomarkers using high-throughput transcriptomic profiling to stratify grades and subtypes, few have resulted in clinically actionable results. This shortcoming can be attributed, in part, to pronounced lab effects that reduce signature robustness and varied individual gene expression among patients with the same tumor. We addressed these issues by uniformly preprocessing publicly available transcriptomic data, comprising 306 tumor samples from three astrocytoma grades (Grade 2, 3, and 4) and 30 non-tumor samples (normal brain as control tissues). Utilizing Differential Rank Conservation (DIRAC), a network-based classification approach, we examined the global and individual patterns of network regulation across tumor grades. Additionally, we applied gene-based approaches to identify genes whose expression changed consistently with increasing tumor grade and evaluated their robustness across multiple studies using statistical sampling. Applying DIRAC, we observed a global trend of greater network dysregulation with increasing tumor aggressiveness. Individual networks displaying greater differences in regulation between adjacent grades play well-known roles in calcium/PKC, EGF, and transcription signaling. Interestingly, many of the 90 individual genes found to monotonically increase or decrease with astrocytoma grade are implicated in cancer-affected processes such as calcium signaling, mitochondrial metabolism, and apoptosis. The fact that specific genes monotonically increase or decrease with increasing astrocytoma grade may reflect shared oncogenic mechanisms among phenotypically similar tumors. This work presents statistically significant results that enable better characterization of different human astrocytoma grades and hopefully can contribute towards improvements in diagnosis and therapy choices. Our results also identify a number of testable hypotheses relating to astrocytoma etiology that may prove helpful in developing much-needed biomarkers for earlier disease detection.

Upregulation of tissue and urinary nicotinamide N-methyltransferase in bladder cancer: potential for the development of a urine-based diagnostic test

Carcinoma of the bladder is one of the most common urologic malignancies occurring worldwide. Diagnosis and monitoring of bladder urothelial carcinoma (UC) are based on cystoscopy and urinary cytology. However, these diagnostic methods still have some limitations, mainly related to invasive nature and lack of sensitivity. New reliable and non-invasive biomarkers for bladder cancer detection are therefore required. To explore the involvement of enzymes of drug metabolism in bladder cancer, in the present study, we analyzed the gene expression profiles of tumor and normal looking tissues obtained from the same patient by cDNA macroarray. The enzyme nicotinamide N-methyltransferase (NNMT) was identified as a highly expressed gene in bladder cancer. RT-PCR, Real-Time PCR, Western blot analysis, and catalytic activity assay, performed on a large cohort of patients with bladder UC, confirmed NNMT upregulation. NNMT mRNA and protein levels were also determined in urine specimens obtained from patients with bladder UC and healthy subjects. We found that NNMT expression levels were significantly higher in patients with bladder tumor compared to controls that showed very low or undetectable amounts of NNMT transcript and protein. Our results indicate that a marked NNMT increase is a peculiar feature of bladder UC and suggest the potential suitability of urine NNMT expression levels determination for early and non-invasive diagnosis of bladder cancer.

RNA-mediated gene silencing of nicotinamide N-methyltransferase is associated with decreased tumorigenicity in human oral carcinoma cells

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. Despite progress in the treatment of OSCC, overall survival has not improved substantially in the last three decades. Therefore, identification of reliable biomarkers becomes essential to develop effective anti-cancer therapy. In this study, we focused on the enzyme Nicotinamide N-methyltransferase (NNMT), which plays a fundamental role in the biotransformation of many xenobiotics. Although several tumors have been associated with abnormal NNMT expression, its role in cancer cell metabolism remains largely unknown. In this report, 7 human oral cancer cell lines were examined for NNMT expression by Real-Time PCR, Western blot and HPLC-based catalytic assay. Subsequently, we evaluated the in vitro effect of shRNA-mediated silencing of NNMT on cell proliferation. In vivo tumorigenicity of oral cancer cells with stable knockdown of NNMT was assayed by using xenograft models. High expression levels of NNMT were found in PE/CA PJ-15 cells, in keeping with the results of Western blot and catalytic activity assay. PE/CA PJ-15 cell line was stably transfected with shRNA plasmids against NNMT and analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and soft agar Assays. Transfected and control cells were injected into athymic mice in order to evaluate the effect of NNMT silencing on tumor growth. NNMT downregulation resulted in decreased cell proliferation and colony formation ability on soft agar. In athymic mice, NNMT silencing induced a marked reduction in tumour volume. Our results show that the downregulation of NNMT expression in human oral carcinoma cells significantly inhibits cell growth in vitro and tumorigenicity in vivo. All these experimental data seem to suggest that NNMT plays a critical role in the proliferation and tumorigenic capacity of oral cancer cells, and its inhibition could represent a potential molecular approach to the treatment of oral carcinoma.

Nicotinamide N-methyltransferase overexpression is associated with Akt phosphorylation and indicates worse prognosis in patients with nasopharyngeal carcinoma

Nicotinamide N-methyltransferase (NNMT) is overexpressed in many human cancers and is associated with poor prognosis. Akt (also known as protein kinase B) is an evolutionarily conserved serine/threonine kinase, serving as a downstream effector of the phosphatidylinositol 3-kinase signaling pathway. NNMT was first identified as a differentially upregulated gene in nasopharyngeal cancer tissues through data mining from published transcriptomic databases. Since no prior study has attempted to evaluate the clinical significance of NNMT or phosphorylated Akt (pAkt) expression in nasopharyngeal cancer, this study explores their expression in a large cohort of patients with nasopharyngeal cancer. The study included 124 nasopharyngeal cancer patients who were free of distant metastasis at initial diagnosis. Pathological slides were reviewed and clinical findings collected. We evaluated the expression of NNMT and pAkt immunohistochemically, stratified them into two groups (high and low expression) and examined the correlation with disease-specific survival (DSS), metastasis-free survival (MeFS), local recurrence-free survival (LRFS), and various clinicopathological factors. NNMT expression was significantly positively associated with pAkt expression. The high expression of both markers was significantly associated with an increment of tumor stage (p = 0.006 and p = 0.006, respectively). High expression of NNMT correlated significantly with a more aggressive clinical course and a significantly shorter DSS. Furthermore, NNMT expression and pAkt expression were strongly predictive of MeFS (p = 0.008; p = 0.0063) and LRFS (p = 0.005; p = 0.0125). In multivariate analysis, high expression of NNMT remained as a robust prognosticator for both end points evaluated. It independently portended inferior DSS (p = 0.02, HR = 1.976) and worse MeFS (p = 0.029, HR = 2.022) after tumor stage (p = 0.033, HR = 2.150; p = 0.028, HR = 2.942, for DSS and LRFS, respectively). We found NNMT positively correlated with pAkt expression and was independent adverse prognosticators of patient survival. NNMT therefore has potential utility as an indicator for prognosis, predicting treatment response to chemotherapy or radiation therapy, and even as a therapeutic target in the future.