Lipid profile in breast cancer: From signaling pathways to treatment strategies

Breast cancer is the most prevalent cancer in women. Metabolic abnormalities, particularly increased lipid synthesis and uptake, impact the onset and progression of the disease. However, the influence of lipid metabolism in breast cancer varies according to the disease stage and patient's hormone status. In postmenopausal patients, obesity is associated with a higher risk and poor prognosis of luminal tumors, while in premenopausal individuals, it is correlated to BRCA mutated tumors. In fact, the tumor's lipid profile may be used to distinguish between HER2+, luminal and BRCA-mutated tumors. Moreover, drug resistance was associated with increased fatty acid synthesis and alterations in membrane composition, impacting its fluidity and spatial subdomains such as lipid rafts. Here, we discuss the subtype-specific lipid metabolism alterations found in breast cancer and the potentiality of its modulation in a clinical setting.

Histidine-based hydrogels via singlet-oxygen photooxidation

The formation of hydrogels by photosensitized oxidation and crosslinking of histidine-derived polymers is demonstrated for the first time. The photooxidation of pendant His mediated by singlet oxygen was used to promote covalent coupling by its dimerization. As a proof-of-concept, two systems were studied: (i) chondroitin sulfate (CS) functionalized with His, and (ii) an elastin-like peptide (ELP) containing His produced by recombinant techniques. Both materials were crosslinked by irradiation at 425 nm in the presence of Zn-porphyrin derivatives yielding His-based hydrogels. The molecular structure and physicochemical properties of ELP-His and other 5 ELPs with photooxidizable amino acids were studied in silica by computer simulation. A correlation between the protein conformation and its elastic properties is discussed. CS-His hydrogels demonstrate larger storage moduli than ELPs with other amino acids. The obtained results show the potential use of photooxidation to create a new type of His-based hydrogels.

Impact of Reck expression and promoter activity in neuronal in vitro differentiation

Reck (REversion-inducing Cysteine-rich protein with Kazal motifs) tumor suppressor gene encodes a multifunctional glycoprotein which inhibits the activity of several matrix metalloproteinases (MMPs), and has the ability to modulate the Notch and canonical Wnt pathways. Reck-deficient neuro-progenitor cells undergo precocious differentiation; however, modulation of Reck expression during progression of the neuronal differentiation process is yet to be characterized. In the present study, we demonstrate that Reck expression levels are increased during in vitro neuronal differentiation of PC12 pheochromocytoma cells and P19 murine teratocarcinoma cells and characterize mouse Reck promoter activity during this process. Increased Reck promoter activity was found upon induction of differentiation in PC12 cells, in accordance with its increased mRNA expression levels in mouse in vitro models. Interestingly, Reck overexpression, prior to the beginning of the differentiation protocol, led to diminished efficiency of the neuronal differentiation process. Taken together, our findings suggest that increased Reck expression at early stages of differentiation diminishes the number of neuron-like cells, which are positive for the beta-3 tubulin marker. Our data highlight the importance of Reck expression evaluation to optimize in vitro neuronal differentiation protocols.

Autism Spectrum Disorder: Signaling Pathways and Prospective Therapeutic Targets

The Autism Spectrum Disorder (ASD) consists of a prevalent and heterogeneous group of neurodevelopmental diseases representing a severe burden to affected individuals and their caretakers. Despite substantial improvement towards understanding of ASD etiology and pathogenesis, as well as increased social awareness and more intensive research, no effective drugs have been successfully developed to resolve the main and most cumbersome ASD symptoms. Hence, finding better treatments, which may act as "disease-modifying" agents, and novel biomarkers for earlier ASD diagnosis and disease stage determination are needed. Diverse mutations of core components and consequent malfunctions of several cell signaling pathways have already been found in ASD by a series of experimental platforms, including genetic associations analyses and studies utilizing pre-clinical animal models and patient samples. These signaling cascades govern a broad range of neurological features such as neuronal development, neurotransmission, metabolism, and homeostasis, as well as immune regulation and inflammation. Here, we review the current knowledge on signaling pathways which are commonly disrupted in ASD and autism-related conditions. As such, we further propose ways to translate these findings into the development of genetic and biochemical clinical tests for early autism detection. Moreover, we highlight some putative druggable targets along these pathways, which, upon further research efforts, may evolve into novel therapeutic interventions for certain ASD conditions. Lastly, we also refer to the crosstalk among these major signaling cascades as well as their putative implications in therapeutics. Based on this collective information, we believe that a timely and accurate modulation of these prominent pathways may shape the neurodevelopment and neuro-immune regulation of homeostatic patterns and, hopefully, rescue some (if not all) ASD phenotypes.

In vitro differentiation of cGMP-grade retinal pigmented epithelium from human embryonic stem cells

Background

The World Health Organization (WHO) estimates that the number of individuals who lose their vision due to retinal degeneration is expected to reach 6 million annually in 2020. The retinal degenerative diseases affect the macula, which is responsible for central and detailed vision. Most macular degeneration, i.e., age-related macular degeneration (AMD) develops in the elderly; however, certain hereditary diseases, such as the Stargardt disease, also affect young people. This degeneration begins with loss of retinal pigmented epithelium (RPE) due to formation of drusen (atrophic) or abnormal vessels (exudative). In wet AMD, numerous drugs are available to successful treat the disease; however, no proven therapy currently is available to treat dry AMD or Stargardt. Since its discovery, human embryonic stem cells (hESCs) have been considered a valuable therapeutic tool. Some evidence has shown that transplantation of RPEs differentiated from hESCs cells can result in recovery of both RPE and photoreceptors and prevent visual loss.

Methods

The human embryonic WA-09 stem cell lineage was cultured under current Good Manufacturing Practices (cGMP) conditions using serum-free media and supplements. The colonies were isolated manually and allowed to spontaneously differentiate into RPE cells.

Results

This simple and effective protocol required minimal manipulation and yielded more than 10e8 RPE cells by the end of the differentiation and enrichment processes, with cells exhibiting a cobblestone morphology and displaying cellular markers and a gene expression profile typical of mature RPE cells. Moreover, the differentiated cells displayed phagocytic activity and only a small percentage of the total cells remained positive for the Octamer-binding transcriptions factor 4 (OCT-4) pluripotency cell marker.

Conclusions

These results showed that functional RPE cells can be produced efficiently and suggested the possibility of scaling-up to aim at therapeutic protocols for retinal diseases associated with RPE degeneration.

Where do we aspire to publish? A position paper on scientific communication in biochemistry and molecular biology

The scientific publication landscape is changing quickly, with an enormous increase in options and models. Articles can be published in a complex variety of journals that differ in their presentation format (online-only or in-print), editorial organizations that maintain them (commercial and/or society-based), editorial handling (academic or professional editors), editorial board composition (academic or professional), payment options to cover editorial costs (open access or pay-to-read), indexation, visibility, branding, and other aspects. Additionally, online submissions of non-revised versions of manuscripts prior to seeking publication in a peer-reviewed journal (a practice known as pre-printing) are a growing trend in biological sciences. In this changing landscape, researchers in biochemistry and molecular biology must re-think their priorities in terms of scientific output dissemination. The evaluation processes and institutional funding for scientific publications should also be revised accordingly. This article presents the results of discussions within the Department of Biochemistry, University of São Paulo, on this subject.

Tamoxifen and bone morphogenic protein-7 modulate fibrosis and inflammation in the peritoneal fibrosis model developed in uremic rats

Background

Peritoneal fibrosis (PF) represents a long-term complication of peritoneal dialysis (PD), affecting peritoneal membrane (PM) integrity and function. Understanding the mechanisms underlying PF development in an uremic environment aiming alternative therapeutic strategies for treating this process is of great interest. The aim of this study was to analyze the effects of tamoxifen (TAM) and recombinant BMP7 (rBMP7) in an experimental model of PF developed in uremic rats.

Methods

To mimic the clinical situation of patients on long-term PD, a combo model, characterized by the combination of PF and CKD with severe uremia, was developed in Wistar rats. PF was induced by intraperitoneal (IP) injections of chlorhexidine gluconate (CG), and CKD was induced by an adenine-rich diet. Uremia was confirmed by severe hypertension, increased blood urea nitrogen (BUN> 120 mg/dL) and serum creatinine levels (> 2 mg/dL). Uremic rats with PF were treated with TAM (10 mg/Kg by gavage) or BMP7 (30 μg/Kg, IP). Animals were followed up for 30 days.

Results

CG administration in uremic rats induced a striking increase in PM thickness, neoangiogenesis, demonstrated by increased capillary density, and failure of ultrafiltration capacity. These morphological and functional changes were blocked by TAM or rBMP7 treatment. In parallel, TAM and rBMP7 significantly ameliorated the PM fibrotic response by reducing α-SMA, extracellular matrix proteins and TGF-ß expression. TAM or rBMP7 administration significantly inhibited peritoneal Smad3 expression in uremic rats with PF, prevented Smad3 phosphorylation, and induced a remarkable up-regulation of Smad7, an intracellular inhibitor of TGFβ/Smad signaling, contributing to a negative modulation of profibrotic genes. Both treatments were also effective in reducing local inflammation, possibly by upregulating IκB-α expression in the PM of uremic rats with PF. In vitro experiments using primary peritoneal fibroblasts activated by TGF-ß confirmed the capacity of TAM or rBMP7 in blocking inflammatory mediators, such as IL-1ß expression.

Conclusions

In conclusion, these findings indicate important roles of TGF-ß/Smad signaling in PF aggravated by uremia, providing data regarding potential therapeutic approaches with TAM or rBMP7 to block this process.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0110-5) contains supplementary material, which is available to authorized users.

Proteome profiling of triple negative breast cancer cells overexpressing NOD1 and NOD2 receptors unveils molecular signatures of malignant cell proliferation

Background

Triple negative breast cancer (TNBC) is a malignancy with very poor prognosis, due to its aggressive clinical characteristics and lack of response to receptor-targeted drug therapy. In TNBC, immune-related pathways are typically upregulated and may be associated with a better prognosis of the disease, encouraging the pursuit for immunotherapeutic options. A number of immune-related molecules have already been associated to the onset and progression of breast cancer, including NOD1 and NOD2, innate immune receptors of bacterial-derived components which activate pro-inflammatory and survival pathways. In the context of TNBC, overexpression of either NOD1or NOD2 is shown to reduce cell proliferation and increase clonogenic potential in vitro. To further investigate the pathways linking NOD1 and NOD2 signaling to tumorigenesis in TNBC, we undertook a global proteome profiling of TNBC-derived cells ectopically expressing each one of these NOD receptors.

Results

We have identified a total of 95 and 58 differentially regulated proteins in NOD1- and NOD2-overexpressing cells, respectively. We used bioinformatics analyses to identify enriched molecular signatures aiming to integrate the differentially regulated proteins into functional networks. These analyses suggest that overexpression of both NOD1 and NOD2 may disrupt immune-related pathways, particularly NF-κB and MAPK signaling cascades. Moreover, overexpression of either of these receptors may affect several stress response and protein degradation systems, such as autophagy and the ubiquitin-proteasome complex. Interestingly, the levels of several proteins associated to cellular adhesion and migration were also affected in these NOD-overexpressing cells.

Conclusions

Our proteomic analyses shed new light on the molecular pathways that may be modulating tumorigenesis via NOD1 and NOD2 signaling in TNBC. Up- and downregulation of several proteins associated to inflammation and stress response pathways may promote activation of protein degradation systems, as well as modulate cell-cycle and cellular adhesion proteins. Altogether, these signals seem to be modulating cellular proliferation and migration via NF-κB, PI3K/Akt/mTOR and MAPK signaling pathways. Further investigation of altered proteins in these pathways may provide more insights on relevant targets, possibly enabling the immunomodulation of tumorigenesis in the aggressive TNBC phenotype.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5523-6) contains supplementary material, which is available to authorized users.

Transcriptomic analysis of purified human cortical microglia reveals age-associated changes

Microglia are essential for CNS homeostasis and innate neuroimmune function, and play important roles in neurodegeneration and brain aging. Here we present gene expression profiles of purified microglia isolated at autopsy from the parietal cortex of 39 human subjects with intact cognition. Overall, genes expressed by human microglia were similar to those in mouse, including established microglial genes CX3CR1, P2RY12 and ITGAM (CD11B). However, a number of immune genes, not identified as part of the mouse microglial signature, were abundantly expressed in human microglia, including TLR, Fcγ and SIGLEC receptors, as well as TAL1 and IFI16, regulators of proliferation and cell cycle. Age-associated changes in human microglia were enriched for genes involved in cell adhesion, axonal guidance, cell surface receptor expression and actin (dis)assembly. Limited overlap was observed in microglial genes regulated during aging between mice and humans, indicating that human and mouse microglia age differently.

Pluripotent Nontumorigenic Adipose Tissue-Derived Muse Cells have Immunomodulatory Capacity Mediated by Transforming Growth Factor-β1

Adult mesenchymal stromal cell‐based interventions have shown promising results in a broad range of diseases. However, their use has faced limited effectiveness owing to the low survival rates and susceptibility to environmental stress on transplantation. We describe the cellular and molecular characteristics of multilineage‐differentiating stress‐enduring (Muse) cells derived from adipose tissue (AT), a subpopulation of pluripotent stem cells isolated from human lipoaspirates. Muse‐AT cells were efficiently obtained using a simple, fast, and affordable procedure, avoiding cell sorting and genetic manipulation methods. Muse‐AT cells isolated under severe cellular stress, expressed pluripotency stem cell markers and spontaneously differentiated into the three germ lineages. Muse‐AT cells grown as spheroids have a limited proliferation rate, a diameter of ∼15 µm, and ultrastructural organization similar to that of embryonic stem cells. Muse‐AT cells evidenced high stage‐specific embryonic antigen‐3 (SSEA‐3) expression (∼60% of cells) after 7–10 days growing in suspension and did not form teratomas when injected into immunodeficient mice. SSEA‐3⁺‐Muse‐AT cells expressed CD105, CD29, CD73, human leukocyte antigen (HLA) class I, CD44, and CD90 and low levels of HLA class II, CD45, and CD34. Using lipopolysaccharide‐stimulated macrophages and antigen‐challenged T‐cell assays, we have shown that Muse‐AT cells have anti‐inflammatory activities downregulating the secretion of proinflammatory cytokines, such as interferon‐γ and tumor necrosis factor‐α. Muse‐AT cells spontaneously gained transforming growth factor‐β1 expression that, in a phosphorylated SMAD2‐dependent manner, might prove pivotal in their observed immunoregulatory activity through decreased expression of T‐box transcription factor in T cells. Collectively, the present study has demonstrated the feasibility and efficiency of obtaining Muse‐AT cells that can potentially be harnessed as immunoregulators to treat immune‐related disorders. Stem Cells Translational Medicine2017;6:161–173

Hypoxia regulates the expression of tissue factor pathway signaling elements in a rat glioma model

Hypoxia and necrosis are fundamental features of glioma, and their emergence is critical for the rapid biological progression of this fatal tumor. The presence of vaso-occlusive thrombus is higher in grade IV tumors [glioblastoma multiforme (GBM)] compared with lower grade tumors, suggesting that the procoagulant properties of the tumor contribute to its aggressive behavior, as well as the establishment of tumor hypoxia and necrosis. Tissue factor (TF), the primary cellular initiator of coagulation, is overexpressed in GBMs and likely favors a thrombotic microenvironment. Phosphatase and tensin homolog (PTEN) loss and hypoxia are two common alterations observed in glioma that may be responsible for TF upregulation. In the present study, ST1 and P7 rat glioma lines, with different levels of aggressiveness, were comparatively analyzed with the aim of identifying differences in procoagulant mechanisms. The results indicated that P7 cells display potent procoagulant activity compared with ST1 cells. Flow cytometric analysis showed less pronounced levels of TF in ST1 cells compared with P7 cells. Notably, P7 cells supported factor X (FX) activation via factor VIIa, whereas no significant FXa generation was observed in ST1 cells. Furthermore, the exposure of phosphatidylserine on the surface of P7 and ST1 cells was investigated. The results supported the assembly of prothrombinase complexes, accounting for the production of thrombin. Furthermore, reverse transcription-quantitative polymerase chain reaction showed that CoCl₂ (known to induce a hypoxic-like stress) led to an upregulation of TF levels in P7 and ST1 cells. Therefore, increased TF expression in P7 cells was accompanied by increased TF procoagulant activity. In addition, hypoxia increased the shedding of procoagulant TF-bearing microvesicles in both cell lines. Finally, hypoxic stress induced by treatment with CoCl₂ upregulated the expression of the PAR1 receptor in both P7 and ST1 cells. In addition to PAR1, P7, but not ST1 cells, expressed higher levels of PAR2 under hypoxic stress. Thus, modulating these molecular interactions may provide additional insights for the development of more efficient therapeutic strategies against aggressive glioma.

RECK is not an independent prognostic marker for breast cancer

Background

The REversion-inducing Cysteine-rich protein with Kazal motif (RECK) is a well-known inhibitor of matrix metalloproteinases (MMPs) and cellular invasion. Although high expression levels of RECK have already been correlated with a better clinical outcome for several tumor types, its main function, as well as its potential prognostic value for breast cancer patients, remain unclear.

Methods

The RECK expression profile was investigated in a panel of human breast cell lines with distinct aggressiveness potential. RECK functional analysis was undertaken using RNA interference methodology. RECK protein levels were also analyzed in 1040 cases of breast cancer using immunohistochemistry and tissue microarrays (TMAs). The association between RECK expression and different clinico-pathological parameters, as well as the overall (OS) and disease-free (DFS) survival rates, were evaluated.

Results

Higher RECK protein expression levels were detected in more aggressive breast cancer cell lines (T4-2, MDA-MB-231 and Hs578T) than in non-invasive (MCF-7 and T47D) and non-tumorigenic (S1) cell lines. Indeed, silencing RECK in MDA-MB-231 cells resulted in elevated levels of pro-MMP-9 and increased invasion compared with scrambled (control) cells, without any effect on cell proliferation. Surprisingly, by RECK immunoreactivity analysis on TMAs, we found no association between RECK positivity and survival (OS and DFS) in breast cancer patients. Even considering the different tumor subtypes (luminal A, luminal B, Her2 type and basal-like) or lymph node status, RECK remained ineffective for predicting the disease outcome. Moreover, by multivariate Cox regression analysis, we found that RECK has no prognostic impact for OS and DFS, relative to standard clinical variables.

Conclusions

Although it continues to serve as an invasion and MMP inhibitor in breast cancer, RECK expression analysis is not useful for prognosis of these patients.

Therapeutic Potential of Laminin–Biodritin Microcapsules for Type 1 Diabetes Mellitus

Pancreatic islet microencapsulation constitutes an attractive therapy for type 1 diabetes mellitus; however, long-term β-cell function remains a major problem. Loss of extracellular matrix interactions during islet isolation dramatically affects β-cell viability. We have previously shown beneficial effects of laminin (LN) in human islet cultures. Herein, we investigated whether LN could improve the outcome of transplantation after islet microencapsulation in Biodritin, an alginate-based material. To test LN-Biodritin stability, microcapsules were subjected to different types of in vitro stress. Focusing on biocompatibility, empty microcapsules were coincubated with the RAW 264.7 macrophage cell line for up to 24 h, and empty beads were implanted IP in mice and retrieved for analyses after 7 and 30 days. Upon culturing for 48 h, mRNA, protein levels, and caspase 3 activity were evaluated in islets microencapsulated with LN-Biodritin. Mice rendered diabetic by streptozotocin injection were transplanted with microencapsulated islets, followed by assessment of body weight, glycemia, and graft function (evaluated by OGTT). Graft efficiency was observed upon microencapsulated islet explantation. The results obtained showed that LN-Biodritin microcapsules were as stable and biocompatible as Biodritin. Modulation of mRNA and protein levels suggested protection against apoptosis and islet stress. Mice transplanted with LN-Biodritin microencapsulated islets presented a better outcome at 198 days postsurgery. Graft explantation led animals to hyperglycemia. In conclusion, LN-Biodritin constitutes a very promising biomaterial for islet transplantation.

Hybrid Membranes of PLLA/Collagen for Bone Tissue Engineering: A Comparative Study of Scaffold Production Techniques for Optimal Mechanical Properties and Osteoinduction Ability

Synthetic and natural polymer association is a promising tool in tissue engineering. The aim of this study was to compare five methodologies for producing hybrid scaffolds for cell culture using poly-l-lactide (PLLA) and collagen: functionalization of PLLA electrospun by (1) dialkylamine and collagen immobilization with glutaraldehyde and by (2) hydrolysis and collagen immobilization with carbodiimide chemistry; (3) co-electrospinning of PLLA/chloroform and collagen/hexafluoropropanol (HFP) solutions; (4) co-electrospinning of PLLA/chloroform and collagen/acetic acid solutions and (5) electrospinning of a co-solution of PLLA and collagen using HFP. These materials were evaluated based on their morphology, mechanical properties, ability to induce cell proliferation and alkaline phosphatase activity upon submission of mesenchymal stem cells to basal or osteoblastic differentiation medium (ODM). Methods (1) and (2) resulted in a decrease in mechanical properties, whereas methods (3), (4) and (5) resulted in materials of higher tensile strength and osteogenic differentiation. Materials yielded by methods (2), (3) and (5) promoted osteoinduction even in the absence of ODM. The results indicate that the scaffold based on the PLLA/collagen blend exhibited optimal mechanical properties and the highest capacity for osteodifferentiation and was the best choice for collagen incorporation into PLLA in bone repair applications.

Molecular cloning and expression analysis of dmrt1 and sox9 during gonad development and male reproductive cycle in the lambari fish, Astyanax altiparanae

BACKGROUND

The dmrt1 and sox9 genes have a well conserved function related to testis formation in vertebrates, and the group of fish presents a great diversity of species and reproductive mechanisms. The lambari fish (Astyanax altiparanae) is an important Neotropical species, where studies on molecular level of sex determination and gonad maturation are scarce.

METHODS

Here, we employed molecular cloning techniques to analyze the cDNA sequences of the dmrt1 and sox9 genes, and describe the expression pattern of those genes during development and the male reproductive cycle by qRT-PCR, and related to histology of the gonad.

RESULTS

Phylogenetic analyses of predicted amino acid sequences of dmrt1 and sox9 clustered A. altiparanae in the Ostariophysi group, which is consistent with the morphological phylogeny of this species. Studies of the gonad development revealed that ovary formation occurred at 58 days after hatching (dah), 2 weeks earlier than testis formation. Expression studies of sox9 and dmrt1 in different tissues of adult males and females and during development revealed specific expression in the testis, indicating that both genes also have a male-specific role in the adult. During the period of gonad sex differentiation, dmrt1 seems to have a more significant role than sox9. During the male reproductive cycle dmrt1 and sox9 are down-regulated after spermiation, indicating a role of these genes in spermatogenesis.

CONCLUSIONS

For the first time the dmrt1 and sox9 were cloned in a Characiformes species. We show that both genes have a conserved structure and expression, evidencing their role in sex determination, sex differentiation and the male reproductive cycle in A. altiparanae. These findings contribute to a better understanding of the molecular mechanisms of sex determination and differentiation in fish.

Roles of Commensal Microbiota in Pancreas Homeostasis and Pancreatic Pathologies

The pancreas plays a central role in metabolism, allowing ingested food to be converted and used as fuel by the cells throughout the body. On the other hand, the pancreas may be affected by devastating diseases, such as pancreatitis, pancreatic adenocarcinoma (PAC), and diabetes mellitus (DM), which generally results in a wide metabolic imbalance. The causes for the development and progression of these diseases are still controversial; therefore it is essential to better understand the underlying mechanisms which compromise the pancreatic homeostasis. The interest in the study of the commensal microbiome increased extensively in recent years, when many discoveries have illustrated its central role in both human physiology and maintenance of homeostasis. Further understanding of the involvement of the microbiome during the development of pathological conditions is critical for the improvement of new diagnostic and therapeutic approaches. In the present review, we discuss recent findings on the behavior and functions played by the microbiota in major pancreatic diseases and provide further insights into its potential roles in the maintenance of pancreatic steady-state activities.

Flavone Induces Cell Death in Human Hepatoma HepG2 Cells

Flavones have received considerable attention because of their antiproliferative properties and selective effects on cancer cells, making them good candidates for use in cancer therapy. In contrast to other flavones, little is known about the effects of the flavone core structure (2-phenyl-4H-1-benzopyran-4one) on cancer cells. Here, we report that flavone induces cell death in human hepatoma HepG2 cells. Furthermore, annexin-V+/PI- and SubG1 populations of HepG2 cells increased after flavone treatment. Exposure of HepG2 to flavone did not result in either cytochrome c release into the cytosol or changes in the mitochondrial membrane potential. Treatment of HepG2 cells with flavone for 24 h reduced the accumulation of intracellular ROS, which correlated with upregulation of Gred, CuZnSOD and MnSOD mRNA levels. Taken together, our results provided useful insights into the mechanism of cell death caused by flavones, in order to evaluate their future application in hepatocarcinoma therapy.

Flavone induces cell death in human hepatoma HepG2 cells

Flavones have received considerable attention because of their antiproliferative properties and selective effects on cancer cells, making them good candidates for use in cancer therapy. In contrast to other flavones, little is known about the effects of the flavone core structure (2-phenyl-4H-1-benzopyran-4one) on cancer cells. Here, we report that flavone induces cell death in human hepatoma HepG2 cells. Furthermore, annexin-V+/PI- and SubG1 populations of HepG2 cells increased after flavone treatment. Exposure of HepG2 to flavone did not result in either cytochrome c release into the cytosol or changes in the mitochondrial membrane potential. Treatment of HepG2 cells with flavone for 24 h reduced the accumulation of intracellular ROS, which correlated with upregulation of Gred, CuZnSOD and MnSOD mRNA levels. Taken together, our results provided useful insights into the mechanism of cell death caused by flavones, in order to evaluate their future application in hepatocarcinoma therapy.

Calcifying Cystic Odontogenic Tumour: immunohistochemical expression of matrix metalloproteinases, their inhibitors (TIMPs and RECK) and inducer (EMMPRIN)

BACKGROUND

Calcifying cyst odontogenic tumour (CCOT) is a rare benign cystic neoplasm of odontogenic origin. MMPs are responsible for extracellular matrix remodelling and, together their inhibitors and inducer, determinate the level of its turnover in pathological processes, leading to an auspicious microenvironment for tumour development. Thus, our goal was to evaluate matrix metalloproteinases (MMPs-2, -7, -9 and -14), their inhibitors (TIMPs-2, -3, -4 and RECK) and its inductor (EMMPRIN) expression in CCOT.

MATERIALS AND METHODS

We used 18 cases of CCOT submitted to immunolocalization of the target proteins and analysed in both neoplastic odontogenic epithelial and stromal compartments.

RESULTS

All molecules evaluated were expressed in both compartments in CCOT. In epithelial layer, immunostaining for MMPs, TIMPs, RECK and EMMPRIN was found in basal, suprabasal spindle and stellate cells surrounding ghost cells and ghost cells themselves, except for MMP-9 and TIMP-2 which were only expressed by ghost cells. In stromal compartment, extracellular matrix, mesenchymal (MC) and endothelial cells (EC) were positive for MMP-2, -7, TIMP-3 and -4, while MMP-9, TIMP-2 and RECK were positive only in MC and MMP-14 only in EC. Statistical significance difference was found between both compartments for MMP-9 (P < 0.001), RECK (P = 0.004) and EMMPRIN (P < 0.001), being more expressed in epithelium than in stroma. Positive correlation between both stromal EMMPRIN and RECK expression was found (R = 0.661, P = 0.003).

CONCLUSIONS

We concluded that these proteins/enzymes are differentially expressed in both epithelium and stroma of CCOT, suggesting an imbalance between MMPs and their inducer/inhibitors may contribute on the tumour behaviour.

A quantitative and humane tail bleeding assay for efficacy evaluation of antihaemophilic factors in haemophilia A mice

The tail bleeding model using haemophilic mice has been used as one of the standard assays for efficacy evaluation of novel antihaemophilic therapies at the preclinical level. A number of different configurations and endpoints have been proposed in the literature for this model, hindering interlaboratory comparisons. A particular configuration, known as the tail bleeding survival assay (TBS), adopted by several groups, involves measuring the ability of conscious haemophilic mice to survive exsanguination following tail transection. Major limitations to this configuration include ethical constraints and impaired quantitative determinations. The aim of this study was to standardize and validate a quantitative haemostatic assay for evaluation of antihaemophilic therapies employing an alternative to TBS, which involves a more humane endpoint associated with stable clot formation. Haemophilic mice were treated with vehicle or different doses of two antihaemophilic reference products licensed in Brazil. The haemostatic response was evaluated by our quantitative tail bleeding haemostatic assay (qTBA) over a period of 120 min and then quantified by dose-response modelling. We demonstrate that our qTBA method allows a direct relationship between the number of animals which achieved full haemostatic response and the dosage of both antihaemophilic factors evaluated over 120 min. In addition, the method sensitivity is suitable to demonstrate the conversion from a severe to a moderate haemophilia phenotype. Our proposed qTBA is easy to implement and constitutes an alternative and more ethical endpoint, which could be effectively used as a surrogate to the commonly employed survival endpoint, allowing quantitative haemostatic response evaluation associated with stable clot formation.

Bone morphogenetic proteins: facts, challenges, and future perspectives

Bone morphogenetic proteins (BMPs) are members of the TGF-β superfamily, acting as potent regulators during embryogenesis and bone and cartilage formation and repair. Cell and molecular biology approaches have unveiled the great complexity of BMP action, later confirmed by transgenic animal studies. Genetic engineering allows for the production of large amounts of BMPs for clinical use, but they have systematically been associated with a delivery system, such as type I collagen and calcium phosphate ceramics, to ensure controlled release and to maximize their biological activity at the surgical site, avoiding systemic diffusion. Clinical orthopedic studies have shown the benefits of FDA-approved recombinant human BMPs (rhBMPs) 2 and 7, but side effects, such as swelling, seroma, and increased cancer risk, have been reported, probably due to high BMP dosage. Several studies have supported the use of BMPs in periodontal regeneration, sinus lift bone-grafting, and non-unions in oral surgery. However, the clinical use of BMPs is growing mainly in off-label applications, with robust evidence to ascertain rhBMPs' safety and efficacy through well-designed, randomized, and double-blind clinical trials. Here we review and discuss the critical data on BMP structure, mechanisms of action, and possible clinical applications.

Proteins differentially expressed in human beta-cells-enriched pancreatic islet cultures and human insulinomas

In view of the great demand for human beta-cells for physiological and medical studies, we generated cell lines derived from human insulinomas which secrete insulin, C-peptide and express neuroendocrine and islet markers. In this study, we set out to characterize their proteomes, comparing them to those of primary beta-cells using DIGE followed by MS. The results were validated by Western blotting. An average of 1800 spots was detected with less than 1% exhibiting differential abundance. Proteins more abundant in human islets, such as Caldesmon, are involved in the regulation of cell contractility, adhesion dependent signaling, and cytoskeletal organization. In contrast, almost all proteins more abundant in insulinoma cells, such as MAGE2, were first described here and could be related to cell survival and resistance to chemotherapy. Our proteomic data provides, for the first time, a molecular snapshot of the orchestrated changes in expression of proteins involved in key processes which could be correlated with the altered phenotype of human beta-cells. Collectively our observations prompt research towards the establishment of bioengineered human beta-cells providing a new and needed source of cultured human beta-cells for beta-cell research, along with the development of new therapeutic strategies for detection, characterization and treatment of insulinomas.

Expression of tissue factor signaling pathway elements correlates with the production of vascular endothelial growth factor and interleukin-8 in human astrocytoma patients

The expression levels of tissue factor (TF), the clotting initiator protein, have been correlated with angiogenesis and the histological grade of malignancy in glioma patients. The pro-tumor function of TF is linked to a family of G protein-coupled receptors known as protease-activated receptors (PARs), which may be activated by blood coagulation proteases. Activation of PARs elicits a number of responses, including the expression of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). In the present study, we analyzed the expression of TF signaling pathway elements (TF, PAR1 and PAR2) and evaluated their correlation with the expression of downstream products (VEGF and IL-8) in human astrocytoma patients. Quantitative PCR (qPCR) showed a significant increase in TF expression in grade IV (glioblastoma) tumors, which was inversely correlated with the expression of the tumor-suppressor PTEN. Immunohistochemistry and qPCR analyses demonstrated a highly significant elevation in the expression of PAR1, but not PAR2, in tumor samples from high-grade astrocytoma patients. The elevated VEGF expression levels detected in the high-grade astrocytoma samples were positively correlated with TF, PAR1 and PAR2 expression. In addition, IL-8 was significantly increased in glioblastoma patients and positively correlated with TF and PAR2 expression. Further in vitro assays employing the human glioma cell lines U87-MG and HOG demonstrated that a synthetic peptide PAR2 agonist stimulated VEGF and IL-8 production. Our findings suggest a role for TF signaling pathway elements in astrocytoma progression, particularly in glioblastoma. Therefore, TF/PAR signaling elements may be suitable targets for the development of new therapies for the treatment of aggressive glioma.

Cell-based interventions to halt autoimmunity in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) results from death of insulin-secreting β cells mediated by self-immune cells, and the consequent inability of the body to maintain insulin levels for appropriate glucose homeostasis. Probably initiated by environmental factors, this disease takes place in genetically predisposed individuals. Given the autoimmune nature of T1DM, therapeutics targeting immune cells involved in disease progress have been explored over the last decade. Several high-cost trials have been attempted to prevent and/or reverse T1DM. Although a definitive solution to cure T1DM is not yet available, a large amount of information about its nature and development has contributed greatly to both the improvement of patient's health care and design of new treatments. In this study, we discuss the role of different types of immune cells involved in T1DM pathogenesis and their therapeutic potential as targets and/or modified tools to treat patients. Recently, encouraging results and new approaches to sustain remnant β cell mass and to increase β cell proliferation by different cell-based means have emerged. Results coming from ongoing clinical trials employing cell therapy designed to arrest T1DM will probably proliferate in the next few years. Strategies under consideration include infusion of several types of stem cells, dendritic cells and regulatory T cells, either manipulated genetically ex vivo or non-manipulated. Their use in combination approaches is another therapeutic alternative. Cell-based interventions, without undesirable side effects, directed to block the uncontrollable autoimmune response may become a clinical reality in the next few years for the treatment of patients with T1DM.

VP22 herpes simplex virus protein can transduce proteins into stem cells

The type I herpes simplex virus VP22 tegument protein is abundant and well known for its ability to translocate proteins from one cell to the other. In spite of some reports questioning its ability to translocate proteins by attributing the results observed to fixation artifacts or simple attachment to the cell membrane, VP22 has been used to deliver several proteins into different cell types, triggering the expected cell response. However, the question of the ability of VP22 to enter stem cells has not been addressed. We investigated whether VP22 could be used as a tool to be applied in stem cell research and differentiation due to its capacity to internalize other proteins without altering the cell genome. We generated a VP22.eGFP construct to evaluate whether VP22 could be internalized and carry another protein with it into two different types of stem cells, namely adult human dental pulp stem cells and mouse embryonic stem cells. We generated a VP22.eGFP fusion protein and demonstrated that, in fact, it enters stem cells. Therefore, this system may be used as a tool to deliver various proteins into stem cells, allowing stem cell research, differentiation and the generation of induced pluripotent stem cells in the absence of genome alterations.

Differential expression of CD90 and CD14 stem cell markers in malignant breast cancer cell lines

The recently emerged concept of cancer stem cell (CSC) has led to a new hypothesis on the basis for tumor progression. Basically, the CSC theory hypothesizes the presence of a hierarchically organized and relatively rare cell population, which is responsible for tumor initiation, self-renewal, and maintenance, in addition to accumulation of mutation and resistance to chemotherapy. CSCs have recently been described in breast cancer. Different genetic markers have been used to isolate breast CSCs, none of which have been correlated with the tumorigenicity or metastatic potential of the cells, limiting their precise characterization and clinical application in the development of therapeutic protocols. Here, we sought for subpopulations of CSCs by analyzing 10 judiciously chosen stem cell markers in a normal breast cell line (MCF10-A) and in four human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435, and Hs578-T) displaying different degrees of metastatic and invasiveness potential. We were able to identify two markers, which are differentially expressed in nontumorigenic versus tumor cells. The CD90 marker was highly expressed in the malignant cell lines. Interestingly, the CD14 molecule displayed higher expression levels in the nontumorigenic cell line. Therefore, we demonstrated that these two markers, which are more commonly used to isolate and characterize stem cells, are differentially expressed in breast tumor cells, when compared with nontumorigenic breast cells.

Expression of NADPH oxidase in human pancreatic islets

AIMS

NADPH oxidase (NOX) is a known source of superoxide anions in phagocytic and non-phagocytic cells. In this study, the presence of this enzyme in human pancreatic islets and the importance of NADPH oxidase in human β-cell function were investigated.

MAIN METHODS AND KEY FINDINGS

In isolated human pancreatic islets, the expression of NADPH oxidase components was evidenced by real-time PCR (p22(PHOX), p47(PHOX) and p67(PHOX)), Western blotting (p47(PHOX) and p67(PHOX)) and immunohistochemistry (p47(PHOX), p67(PHOX) and gp91(PHOX)). Immunohistochemistry experiments showed co-localization of p47(PHOX), p67(PHOX) and gp91(PHOX) (isoform 2 of NADPH oxidase-NOX2) with insulin secreting cells. Inhibition of NADPH oxidase activity impaired glucose metabolism and glucose-stimulated insulin secretion.

SIGNIFICANCE

These findings demonstrate the presence of the main intrinsic components of NADPH oxidase comprising the NOX2 isoform in human pancreatic islets, whose activity also contributes to human β-cell function.

Epithelial-mesenchymal transition: implications in cancer progression and metastasis

During the past few years, Epithelial-Mesenchymal Transition (EMT) has emerged as one of the most hot spots in clinical research. Its existence in human tumors can form the basis for explaining characteristics of cancer progression and metastasis, as well as certain cases of drug resistance and relapses after treatment. These cellular responses are tightly regulated by intracellular signaling pathways evoked by humoral factors that include growth factors, chemokines and cytokines. Indeed, several gene regulatory programs known to promote EMT during development have recently been discovered to play key roles in cancer progression. A deeper understanding of the cellular and molecular basis of these different programs should aid in both the development of better diagnosis methods, as well as of specific treatments for invasive cancer. In this review we set out to summarize recent novel insights into the molecular players underlying EMT and its relation with cancer progression and metastasis.

Redox control of 20S proteasome gating

The proteasome is the primary contributor in intracellular proteolysis. Oxidized or unstructured proteins can be degraded via a ubiquitin- and ATP-independent process by the free 20S proteasome (20SPT). The mechanism by which these proteins enter the catalytic chamber is not understood thus far, although the 20SPT gating conformation is considered to be an important barrier to allowing proteins free entrance. We have previously shown that S-glutathiolation of the 20SPT is a post-translational modification affecting the proteasomal activities.

AIMS

The goal of this work was to investigate the mechanism that regulates 20SPT activity, which includes the identification of the Cys residues prone to S-glutathiolation.

RESULTS

Modulation of 20SPT activity by proteasome gating is at least partially due to the S-glutathiolation of specific Cys residues. The gate was open when the 20SPT was S-glutathiolated, whereas following treatment with high concentrations of dithiothreitol, the gate was closed. S-glutathiolated 20SPT was more effective at degrading both oxidized and partially unfolded proteins than its reduced form. Only 2 out of 28 Cys were observed to be S-glutathiolated in the proteasomal α5 subunit of yeast cells grown to the stationary phase in glucose-containing medium.

INNOVATION

We demonstrate a redox post-translational regulatory mechanism controlling 20SPT activity.

CONCLUSION

S-glutathiolation is a post-translational modification that triggers gate opening and thereby activates the proteolytic activities of free 20SPT. This process appears to be an important regulatory mechanism to intensify the removal of oxidized or unstructured proteins in stressful situations by a process independent of ubiquitination and ATP consumption. Antioxid. Redox Signal. 16, 1183-1194.

Abstract 443: Expression of the RECK tumor and metastasis suppressor gene in human breast cancer: a poor prognosis marker

Metastasis is the main cause of mortality in breast cancer human patients. The organized breakdown of the extracellular matrix (ECM) compounds by matrix metalloproteinases (MMPs) is the key event in this metastatic process. Consistent with their role in tumor progression, high levels of several MMP family members have been shown to be correlated with poor prognosis. The MMP activities are tightly regulated by their inhibitors, namely: the metalloproteinases tissue inhibitors (TIMPs) and the membrane-associated inhibitor (RECK - Reversion-inducing Cysteine-rich protein with Kazal motifs). Due to RECK's ability to down modulate MMPs (MMP-2, 9 and 14), it is described as an important inhibitor of invasion and metastasis in several types of cancer. In order to investigate possible correlations between the RECK expression profile and clinical-pathological data in a breast cancer model, we evaluated the RECK protein in 1,040 tissue samples from invasive breast tumors using Tissue Microarray Assays (TMA). Associations between RECK expression and different clinical-pathological parameters and other biomarkers were evaluated using the Chi-square test. RECK immunoreactivity was significantly associated with higher SBR grade (p&lt;0.05) and TNM stage (p=0.002). Moreover, higher RECK expression levels were correlated with p53 (p&lt;0.001), her-2 (p=0.011), CK5,6 (p&lt;0.001) and egfr (p&lt;0.001) positivity. We also analyzed the relationship between RECK expression and the patient outcome, using Kaplan-Meier curves, demonstrating that patients with RECK positive tumors display significantly shorter disease free survival time (p=0.031) than those with RECK negative tumors. Furthermore, RECK expression was positively correlated with short disease free survival in five-years in patients diagnosed with tumors: low SBR grade (p=0.03), her-2 negative (p&lt;0.05) and luminal markers (CK8/CK18) positive (p=0.02 and p=0.003, respectively). In addition, RECK was a predictor of poor prognosis for post-menopause (p=0.011) and patients older than 50 years (p=0.05). All together, our results indicate that higher RECK expression is associated with poor prognosis variables, being a predictor of shorter disease-free survival in five years. Moreover, we verified that RECK is a biomarker of poor prognosis mainly for patients diagnosed with less aggressive breast tumor. Therefore, in contrast to other tumor types, our results indicate that RECK is related to a more aggressive phenotype. Support: FAPESP, CNPq, FINEP, CAPES, BNDES

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 443. doi:1538-7445.AM2012-443

Islet versus pancreas transplantation in Brazil: Defining criteria for pancreas allocation decision

BACKGROUND

Many studies have evaluated whether there are characteristics related to pancreas donors and the islet isolation process that can influence pancreatic islet yield. However, this analysis has not yet been performed in Brazil, one of the world leaders in whole pancreas organ transplantation (WOPT), where pancreas allocation for pancreatic islet transplantation (PIT) has no officially defined criteria. Definition of parameters that would predict the outcome of islet isolation from local pancreas donors would be useful for defining allocation priority in Brazil.

OBJECTIVE

To analyze the relationship between multiple donor-related and islet isolation variables with the total number of isolated pancreatic islet equivalents (IEQ) in a brazilian sample of pancreas donors.

METHODS

Several variables were analyzed in 74 pancreata relative to the outcome of total IEQs obtained at the end of the process.

RESULTS

In univariate analysis, body mass index (BMI) (p = 0.003), the presence of fatty infiltrates in the pancreas as observed during harvesting (p = 0.042) and pancreas digestion time (p = 0.046) were identified as variables related to a greater IEQ yield. In a multivariate analysis a statistically significant contribution to the variability of islet yield was found only for the BMI (p = 0.017). A ROC curve defined a BMI = 30 as a cut-off point, with pancreata from donors with BMI > 30 yielding more islets than donors with BMI < 30 (p< 0.001).

CONCLUSION

These data reinforce the importance of the donor BMI as a defining parameter for successful islet isolation and establishes this variable as a potential pancreas allocation criterion in Brazil, where there is unequal competition for good quality organs between WOPT and PIT.

Unveiling novel genes upregulated by both rhBMP2 and rhBMP7 during early osteoblastic transdifferentiation of C2C12 cells

FINDINGS

We set out to analyse the gene expression profile of pre-osteoblastic C2C12 cells during osteodifferentiation induced by both rhBMP2 and rhBMP7 using DNA microarrays. Induced and repressed genes were intercepted, resulting in 1,318 induced genes and 704 repressed genes by both rhBMP2 and rhBMP7. We selected and validated, by RT-qPCR, 24 genes which were upregulated by rhBMP2 and rhBMP7; of these, 13 are related to transcription (Runx2, Dlx1, Dlx2, Dlx5, Id1, Id2, Id3, Fkhr1, Osx, Hoxc8, Glis1, Glis3 and Cfdp1), four are associated with cell signalling pathways (Lrp6, Dvl1, Ecsit and PKCδ) and seven are associated with the extracellular matrix (Ltbp2, Grn, Postn, Plod1, BMP1, Htra1 and IGFBP-rP10). The novel identified genes include: Hoxc8, Glis1, Glis3, Ecsit, PKCδ, LrP6, Dvl1, Grn, BMP1, Ltbp2, Plod1, Htra1 and IGFBP-rP10.

BACKGROUND

BMPs (bone morphogenetic proteins) are members of the TGFβ (transforming growth factor-β) super-family of proteins, which regulate growth and differentiation of different cell types in various tissues, and play a critical role in the differentiation of mesenchymal cells into osteoblasts. In particular, rhBMP2 and rhBMP7 promote osteoinduction in vitro and in vivo, and both proteins are therapeutically applied in orthopaedics and dentistry.

CONCLUSION

Using DNA microarrays and RT-qPCR, we identified both previously known and novel genes which are upregulated by rhBMP2 and rhBMP7 during the onset of osteoblastic transdifferentiation of pre-myoblastic C2C12 cells. Subsequent studies of these genes in C2C12 and mesenchymal or pre-osteoblastic cells should reveal more details about their role during this type of cellular differentiation induced by BMP2 or BMP7. These studies are relevant to better understanding the molecular mechanisms underlying osteoblastic differentiation and bone repair.

Involvement of catalase in the apoptotic mechanism induced by apigenin in HepG2 human hepatoma cells

Apigenin has been reported to inhibit proliferation of cancer cells; however, the mechanism underlying its action is not completely understood. Here, we evaluated the effects of apigenin on the levels of expression and activity of antioxidant enzymes, and the involvement of ROS in the mechanism of cell death induced by apigenin in HepG2 human hepatoma cells. Upon treatment with apigenin, HepG2 cells displayed a reduction in cell viability in a dose- and time-dependent manner, and some morphological changes. In addition, apigenin treatment induced ROS generation and significantly decreased the mRNA levels and activity of catalase and levels of intracellular GSH. On the other hand, apigenin treatment did not alter the expression or activity levels of other antioxidant enzymes. Addition of exogenous catalase significantly reduced the effects of apigenin on HepG2 cell death. We also demonstrated that HepG2 cells are more sensitive to apigenin-mediated cell death than are primary cultures of mouse hepatocytes, suggesting a differential toxic effect of this agent in tumor cells. Our results suggest that apigenin-induced apoptosis in HepG2 cells may be mediated by a H(2)O(2)-dependent pathway via reduction of the antioxidant defenses.

Recombinant human prolactin promotes human beta cell survival via inhibition of extrinsic and intrinsic apoptosis pathways

AIMS/HYPOTHESIS

Transplantation of pancreatic islets constitutes a promising alternative treatment for type 1 diabetes. However, it is limited by the shortage of organ donors. Previous results from our laboratory have demonstrated beneficial effects of recombinant human prolactin (rhPRL) treatment on beta cell cultures. We therefore investigated the role of rhPRL action in human beta cell survival, focusing on the molecular mechanisms involved in this process.

METHODS

Human pancreatic islets were isolated using an automated method. Islet cultures were pre-treated in the absence or presence of rhPRL and then subjected to serum starvation or cytokine treatment. Beta cells were labelled with Newport green and apoptosis was evaluated using flow cytometry analysis. Levels of BCL2 gene family members were studied by quantitative RT-PCR and western blot. Caspase-8, -9 and -3 activity, as well as nitric oxide production, were evaluated by fluorimetric assays.

RESULTS

The proportion of apoptotic beta cells was significantly lowered in the presence of rhPRL under both cell death-induced conditions. We also demonstrated that cytoprotection may involve an increase of BCL2/BAX ratio, as well as inhibition of caspase-8, -9 and -3.

CONCLUSIONS/INTERPRETATION

Our study provides relevant evidence for a protective effect of lactogens on human beta cell apoptosis. The results also suggest that the improvement of cell survival may involve, at least in part, inhibition of cell death pathways controlled by the BCL2 gene family members. These findings are highly relevant for improvement of the islet isolation procedure and for clinical islet transplantation.

Abstract 2354: Characterization of three novel splice variants of the RECK tumor and metastasis suppressor gene

REversion-inducing Cysteine-rich protein with Kazal motifs (RECK) encodes a membrane-anchored protein which suppresses both invasion and metastasis by negatively regulating at least three MMP′s, namely: MMP-9, MMP-2 and MT1-MMP. Matrix metalloproteinase (MMP) family members belong to the group of Zn2+ dependent proteolytic enzymes, which are key elements responsible for extracellular matrix (MEC) collapse, being, therefore, directly involved in tumor invasiveness and metastasis. MEC degradation by MMPs not only facilitates tumor invasion, but, also, affects the behavior of tumor and adjacent cells, leading to cancer progression. In general, the relative levels of MMPs increase with tumor progression. Other RECK targets have been identified, such as the extracellular metalloproteinases ADAM10 and CD13/ aminopeptidase N. A positive correlation has been observed between the abundance of RECK expression in tumor samples and better prognosis for patients with gastric, lung, pancreatic and colorectal cancers. Recent studies showed mutations in splicing cis regulatory elements and alterations in the cellular splicing regulatory machinery leading to changes in the splicing pattern of several cancer-related genes, such as CD44, BRCA1, APC, p53 and FHT. In the present study, three novel alternative isoforms of the RECK tumor suppressor gene, namely RECK B (1,548b), RECK D (1,737b) and RECK I (1,101b) were isolated by RT-PCR and their expression profiles were investigated using quantitative real time RT-PCR assays in a normal tissue RNA panel and during human glioma progression. Our results show that RECK isoforms display independent expression patterns when compared to the canonical form, indicating a more complex role for both the canonical and the alternative RECK isoforms in glioma progression. Support: FAPESP, CNPq, FINEP, BNDES, MCT, MS

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2354. doi:10.1158/1538-7445.AM2011-2354

Cloning and characterization of a novel alternatively spliced transcript of the human CHD7 putative helicase

Background

The CHD7 (Chromodomain Helicase DNA binding protein 7) gene encodes a member of the chromodomain family of ATP-dependent chromatin remodeling enzymes. Mutations in the CHD7 gene are found in individuals with CHARGE, a syndrome characterized by multiple birth malformations in several tissues. CHD7 was identified as a binding partner of PBAF complex (Polybromo and BRG Associated Factor containing complex) playing a central role in the transcriptional reprogramming process associated to the formation of multipotent migratory neural crest, a transient cell population associated with the genesis of various tissues. CHD7 is a large gene containing 38 annotated exons and spanning 200 kb of genomic sequence. Although genes containing such number of exons are expected to have several alternative transcripts, there are very few evidences of alternative transcripts associated to CHD7 to date indicating that alternative splicing associated to this gene is poorly characterized.

Findings

Here, we report the cloning and characterization by experimental and computational studies of a novel alternative transcript of the human CHD7 (named CHD7 CRA_e), which lacks most of its coding exons. We confirmed by overexpression of CHD7 CRA_e alternative transcript that it is translated into a protein isoform lacking most of the domains displayed by the canonical isoform. Expression of the CHD7 CRA_e transcript was detected in normal liver, in addition to the DU145 human prostate carcinoma cell line from which it was originally isolated.

Conclusions

Our findings indicate that the splicing event associated to the CHD7 CRA_e alternative transcript is functional. The characterization of the CHD7 CRA_e novel isoform presented here not only sets the basis for more detailed functional studies of this isoform, but, also, contributes to the alternative splicing annotation of the CHD7 gene and the design of future functional studies aimed at the elucidation of the molecular functions of its gene products.

Glypican-3 reexpression regulates apoptosis in murine adenocarcinoma mammary cells modulating PI3K/Akt and p38MAPK signaling pathways

Glypican-3 (GPC3) is a proteoglycan involved in proliferation and cell survival. Several reports demonstrated that GPC3 is downregulated in some tumors, such as breast cancer. Previously, we determined that GPC3 reexpression in the murine mammary adenocarcinoma LM3 cells induced an impairment of their invasive and metastatic capacities, associated with a decrease of their motility and an increase of their cell death. We demonstrated that GPC3 inhibits canonical Wnt signaling, as well as it activates non canonical pathway. Now, we identified signaling pathways responsible for the pro-apoptotic role of GPC3 in LM3 cells. We found for the first time that GPC3 inhibits the PI3K/Akt anti-apoptotic pathway while it stimulates the p38MAPK stress-activated one. We report a concomitant modulation of CDK inhibitors as well as of pro- and anti-apoptotic molecules. Our results provide new clues regarding the mechanism involved in the modulation induced by GPC3 of mammary tumor cell growth and survival.

Ixolaris, a tissue factor inhibitor, blocks primary tumor growth and angiogenesis in a glioblastoma model

BACKGROUND

The expression levels of the clotting initiator protein Tissue Factor (TF) correlate with vessel density and the histological malignancy grade of glioma patients. Increased procoagulant tonus in high grade tumors (glioblastomas) also indicates a potential role for TF in progression of this disease, and suggests that anticoagulants could be used as adjuvants for its treatment.

OBJECTIVES

We hypothesized that blocking of TF activity with the tick anticoagulant Ixolaris might interfere with glioblastoma progression.

METHODS AND RESULTS

TF was identified in U87-MG cells by flow-cytometric and functional assays (extrinsic tenase). In addition, flow-cytometric analysis demonstrated the exposure of phosphatidylserine in the surface of U87-MG cells, which supported the assembly of intrinsic tenase (FIXa/FVIIIa/FX) and prothrombinase (FVa/FXa/prothrombin) complexes, accounting for the production of FXa and thrombin, respectively. Ixolaris effectively blocked the in vitro TF-dependent procoagulant activity of the U87-MG human glioblastoma cell line and attenuated multimolecular coagulation complexes assembly. Notably, Ixolaris inhibited the in vivo tumorigenic potential of U87-MG cells in nude mice, without observable bleeding. This inhibitory effect of Ixolaris on tumor growth was associated with downregulation of VEGF and reduced tumor vascularization.

CONCLUSION

Our results suggest that Ixolaris might be a promising agent for anti-tumor therapy in humans.

Quality control and reproducibility in DNA microarray experiments

Biological experiments are usually set up in technical replicates (duplicates or triplicates) in order to ensure reproducibility and, to assess any significant error introduced during the experimental process. The first step in biological data analysis is to check the technical replicates and to confirm that the error of measure is small enough to be of no concern. However, little attention has been paid to this part of analysis. Here, we propose a general process to estimate the error of measure and consequently, to provide an interpretable and objective way to ensure the technical replicates' quality. Particularly, we illustrate our application in a DNA microarray dataset set up in technical duplicates.

Mesenchymal stem cells delivered at the subcapsule of the kidney ameliorate renal disease in the rat remnant kidney model

Stem cells (SC) are potential therapeutic tools in the treatment of chronic renal diseases. Number and engraftment of SC in the injured sites are important for possible differentiation into renal cells and paracrine effect. The aim of this study was to analyze the effect of subcapsular injection of mesenchymal stem cells (MSC) in the 5/6 nephrectomy model (5/6 Nx). MSC obtained from Wistar rats were isolated by their capacity to adhere to plastic surfaces, characterized by flow cytometry, and analyzed by their differentiation potential into osteoblasts. MSC (2 x 10(5)) were injected into the subcapsule of the remnant kidney of male Wistar rats, and were followed for 15 or 30 days. 5/6 Nx rats showed significant hypertension at 15 and 30 days, which was reduced by MSC at 30 days. Increased albuminuria and serum creatinine at 15 and 30 days in 5/6 Nx rats were also reduced by subcapsular injection of MSC. We also observed a significant reduction of glomerulosclerosis index 30 days after injection of MSC. 4-6 diamidino-2-phenylindole dihydrochloride (DAPI)-stained MSC showed a migration of these cells into renal parenchyma 5, 15, and 30 days after subcapsular injection. In conclusion, our data demonstrated that subcapsular injection of MSC in 5/6 Nx rats is associated with renoprotective effects. These results suggest that locally implanted MSC in the kidney allow a large number of cells to migrate into the injured sites and demonstrate that subcapsular injection represent an effective route for MSC delivery.

Generation and characterization of human insulin-releasing cell lines

Background

The in vitro culture of insulinomas provides an attractive tool to study cell proliferation and insulin synthesis and secretion. However, only a few human beta cell lines have been described, with long-term passage resulting in loss of insulin secretion. Therefore, we set out to establish and characterize human insulin-releasing cell lines.

Results

We generated ex-vivo primary cultures from two independent human insulinomas and from a human nesidioblastosis, all of which were cultured up to passage number 20. All cell lines secreted human insulin and C-peptide. These cell lines expressed neuroendocrine and islets markers, confirming the expression profile found in the biopsies. Although all beta cell lineages survived an anchorage independent culture, none of them were able to invade an extracellular matrix substrate.

Conclusion

We have established three human insulin-releasing cell lines which maintain antigenic characteristics and insulin secretion profiles of the original tumors. These cell lines represent valuable tools for the study of molecular events underlying beta cell function and dysfunction.

Correlation between MMPs and their inhibitors in breast cancer tumor tissue specimens and in cell lines with different metastatic potential

Background

The metastatic disease rather than the primary tumor itself is responsible for death in most solid tumors, including breast cancer. The role of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs) and Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) in the metastatic process has previously been established. However, in all published studies only a limited number of MMPs/MMP inhibitors was analyzed in a limited number of cell lines. Here, we propose a more comprehensive approach by analyzing the expression levels of several MMPs (MMP-2, MMP-9 and MMP-14) and MMP inhibitors (TIMP-1, TIMP-2 and RECK) in different models (five human breast cancer cell lines, 72 primary breast tumors and 30 adjacent normal tissues).

Methods

We analyzed the expression levels of MMP-2, MMP-9 and MMP-14 and their inhibitors (TIMP-1, TIMP-2 and RECK) by quantitative RT-PCR (qRT-PCR) in five human breast cancer cell lines presenting increased invasiveness and metastatic potential, 72 primary breast tumors and 30 adjacent normal tissues. Moreover, the role of cell-extracellular matrix elements interactions in the regulation of expression and activity of MMPs and their inhibitors was analyzed by culturing these cell lines on plastic or on artificial ECM (Matrigel).

Results

The results demonstrated that MMPs mRNA expression levels displayed a positive and statistically significant correlation with the transcriptional expression levels of their inhibitors both in the cell line models and in the tumor tissue samples. Furthermore, the expression of all MMP inhibitors was modulated by cell-Matrigel contact only in highly invasive and metastatic cell lines. The enzyme/inhibitor balance at the transcriptional level significantly favors the enzyme which is more evident in tumor than in adjacent non-tumor tissue samples.

Conclusion

Our results suggest that the expression of MMPs and their inhibitors, at least at the transcriptional level, might be regulated by common factors and signaling pathways. Therefore, the multi-factorial analysis of these molecules could provide new and independent prognostic information contributing to the determination of more adequate therapy strategies for each patient.

Experimental nodel of C6 brain tumors in athymic rats

Malignant brain tumor experimental models tend to employ cells that are immunologically compatible with the receptor animal. In this study, we have proposed an experimental model of encephalic tumor development by injecting C6 cells into athymic Rowett rats, aiming at reaching a model which more closely resembles to the human glioma tumor. In our model, we observed micro-infiltration of tumor cell clusters in the vicinity of the main tumor mass, and of more distal isolated tumor cells immersed in normal encephalic parenchyma. This degree of infiltration is superior to that usually observed in other C6 models.