Software BreastAnalyser for the semi-automatic analysis of breast cancer immunohistochemical images.

Breast cancer is the most diagnosed cancer worldwide and represents the fifth cause of cancer mortality globally. It is a highly heterogeneous disease, that comprises various molecular subtypes, often diagnosed by immunohistochemistry. This technique is widely employed in basic, translational and pathological anatomy research, where it can support the oncological diagnosis, therapeutic decisions and biomarker discovery. Nevertheless, its evaluation is often qualitative, raising the need for accurate quantitation methodologies. We present the software BreastAnalyser, a valuable and reliable tool to automatically measure the area of 3,3'-diaminobenzidine tetrahydrocholoride (DAB)-brown-stained proteins detected by immunohistochemistry. BreastAnalyser also automatically counts cell nuclei and classifies them according to their DAB-brown-staining level. This is performed using sophisticated segmentation algorithms that consider intrinsic image variability and save image normalization time. BreastAnalyser has a clean, friendly and intuitive interface that allows to supervise the quantitations performed by the user, to annotate images and to unify the experts' criteria. BreastAnalyser was validated in representative human breast cancer immunohistochemistry images detecting various antigens. According to the automatic processing, the DAB-brown area was almost perfectly recognized, being the average difference between true and computer DAB-brown percentage lower than 0.7 points for all sets. The detection of nuclei allowed proper cell density relativization of the brown signal for comparison purposes between the different patients. BreastAnalyser obtained a score of 85.5 using the system usability scale questionnaire, which means that the tool is perceived as excellent by the experts. In the biomedical context, the connexin43 (Cx43) protein was found to be significantly downregulated in human core needle invasive breast cancer samples when compared to normal breast, with a trend to decrease as the subtype malignancy increased. Higher Cx43 protein levels were significantly associated to lower cancer recurrence risk in Oncotype DX-tested luminal B HER2- breast cancer tissues. BreastAnalyser and the annotated images are publically available https://citius.usc.es/transferencia/software/breastanalyser for research purposes.

Adaptation and validation of the PAC-19QoL-specific quality of life questionnaire for the Spanish population with long COVID.

INTRODUCTION: The post-acute (long) COVID-19 Quality of Life instrument is the only specific instrument designed to assess the quality of life in long COVID patients. The present study aims to make a transcultural adaptation and validation into Spanish of the disease-specific (long COVID) quality of life instrument, post-acute (long) COVID-19 Quality of Life, to have a tool for objective measurement of quality of life in this population. METHODS: A descriptive cross-sectional study was divided into two phases. In phase one, the translation and cultural adaptation of the questionnaire was performed, while in phase two, the questionnaire was validated. The Spanish version of the questionnaire was used with a sample of 206 people, 40 males (19.4%) and 166 females (80.6%), with an age range between 21 and 70 years old. Participants completed the questionnaire through an online platform. Internal consistency, construct validity, convergent validity, test-retest reliability, and ceiling and floor effects of the Spanish version were analyzed. RESULTS: The Spanish version of the post-acute (long) COVID-19 Quality of Life instrument showed high internal consistency, with Cronbach's alpha= 0.922 and an intraclass correlation coefficient of 0.936. Mean scores obtained in the PAC-19QoL and SF-12 questionnaires showed that those who had a worse quality of life in the SF-12 tool also a had worse quality of life in the PAC-19QoL tool. CONCLUSIONS: This study shows that the Spanish version of the post-acute (long) COVID-19 Quality of Life instrument is an appropriate and valid tool for assessing the quality of life of long COVID patients.

Prognostic value of the immune target CEACAM6 in cancer: a meta-analysis.

BACKGROUND: Identification of membrane proteins differentially expressed on tumor cells is a key step in drug development. The carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a cell adhesion protein belonging to the immunoglobulin superfamily. Here, we explore the prognostic role CEACAM6 expression on patient outcome in cancer. METHODS: A systematic search for studies evaluating the association between tumor expression of CEACAM6 and overall survival (OS) and disease-free survival (DFS) was performed. Hazard ratios (HR) were pooled in a meta-analysis using generic inverse variance and random effect modeling. Subgroup analyses were conducted based on tumor type and method of HR extraction. RESULTS: Sixteen studies met the inclusion criteria. CEACAM6 expression was associated with worse OS [HR = 1.96, 95% confidence interval (CI) = 1.51-2.53], and DFS (HR = 2.49, 95% CI = 2.01-3.07) with subgroup analysis showing no significant differences between disease site subgroups. CONCLUSIONS: High expression of CEACAM6 is associated with worse OS and DFS in different malignancies. CEACAM6 is a target for the future development of novel therapeutics.

Characterization of Permeability Barrier Dysfunction in a Murine Model of Cutaneous Field Cancerization Following Chronic UV-B Irradiation: Implications for the Pathogenesis of Skin Cancer.

Chronic ultraviolet B (UV-B) irradiation is known to be one of the most important hazards acting on the skin and poses a risk of developing photoaging, skin with cutaneous field cancerization (CFC), actinic keratosis (AKs), and squamous cell carcinomas (SCCs). Most of the UV-B light is absorbed in the epidermis, affecting the outermost cell layers, the stratum corneum, and the stratum granulosum, which protects against this radiation and tries to maintain the permeability barrier. In the present work, we show an impairment in the transepidermal water loss, stratum corneum hydration, and surface pH after chronic UV-B light exposure in an immunologically intact mouse model (SKH1 aged mice) of skin with CFC. Macroscopic lesions of AKs and SCCs may develop synchronically or over time on the same cutaneous surface due to both the presence of subclinical AKs and in situ SCC, but also the accumulation of different mutations in keratinocytes. Focusing on skin with CFC, yet without the pathological criteria of AKs or SCC, the presence of p53 immunopositive patches (PIPs) within the epidermis is associated with these UV-B-induced mutations. Reactive epidermis to chronic UV-B exposure correlated with a marked hyperkeratotic hyperplasia, hypergranulosis, and induction of keratinocyte hyperproliferation, while expressing an upregulation of filaggrin, loricrin, and involucrin immunostaining. However, incidental AKs and in situ SCC might show neither hypergranulosis nor upregulation of differentiation markers in the upper epidermis. Despite the overexpression of filaggrin, loricrin, involucrin, lipid enzymes, and ATP-binding cassette subfamily A member 12 (ABCA12) after chronic UV-B irradiation, the permeability barrier, stratum corneum hydration, and surface pH were severely compromised in the skin with CFC. We interpret these results as an attempt to restore the permeability barrier homeostasis by the reactive epidermis, which fails due to ultrastructural losses in stratum corneum integrity, higher pH on skin surface, abundant mast cells in the dermis, and the common presence of incidental AKs and in situ SCC. As far as we know, this is the first time that the permeability barrier has been studied in the skin with CFC in a murine model of SCC induced after chronic UV-B irradiation at high doses. The impairment in the permeability barrier and the consequent keratinocyte hyperproliferation in the skin of CFC might play a role in the physiopathology of AKs and SCCs.

Mapping of Genomic Vulnerabilities in the Post-Translational Ubiquitination, SUMOylation and Neddylation Machinery in Breast Cancer.

The dysregulation of post-translational modifications (PTM) transversally impacts cancer hallmarks and constitutes an appealing vulnerability for drug development. In breast cancer there is growing preclinical evidence of the role of ubiquitin and ubiquitin-like SUMO and Nedd8 peptide conjugation to the proteome in tumorigenesis and drug resistance, particularly through their interplay with estrogen receptor signaling and DNA repair. Herein we explored genomic alterations in these processes using RNA-seq and mutation data from TCGA and METABRIC datasets, and analyzed them using a bioinformatic pipeline in search of those with prognostic and predictive capability which could qualify as subjects of drug research. Amplification of UBE2T, UBE2C, and BIRC5 conferred a worse prognosis in luminal A/B and basal-like tumors, luminal A/B tumors, and luminal A tumors, respectively. Higher UBE2T expression levels were predictive of a lower rate of pathological complete response in triple negative breast cancer patients following neoadjuvant chemotherapy, whereas UBE2C and BIRC5 expression was higher in luminal A patients with tumor relapse within 5 years of endocrine therapy or chemotherapy. The transcriptomic signatures of USP9X and USP7 gene mutations also conferred worse prognosis in luminal A, HER2-enriched, and basal-like tumors, and in luminal A tumors, respectively. In conclusion, we identified and characterized the clinical value of a group of genomic alterations in ubiquitination, SUMOylation, and neddylation enzymes, with potential for drug development in breast cancer.

Topical Applications of Thiosulfinate-Enriched Allium sativum Extract Accelerates Acute Cutaneous Wound Healing in Murine Model.

OBJECTIVE: To determine whether topical applications of thiosulfinate-enriched Allium sativum extract (TASE) can accelerate acute cutaneous wound healing (WH) in a murine model. METHODS: Keratinocyte viability and in vitro wound closure were assessed in keratinocyte cultures. Effects of topical TASE (0.5 µg/mL of allicin in 97% ethanol) on acute cutaneous WH were determined in a murine model of acute cutaneous wound. Twelve mice were alternately assigned to the vehicle- and TASE-treated groups (n=6 per group). Expression levels of mRNA for keratinocyte differentiation marker-related proteins (filaggrin, loricrin and involucrin) and lipid synthetic enzymes (elongation of very long chain fatty acids protein 4 (ELOVL4), fatty acid synthase (FA2H), 3-hydroxy- 3-methyl-glutaryl-coenzyme A reductase (HMGCoA), and serine palmitoyltransferase (SPT)) were assessed using real-time quantitative polymerase chain reaction on day 3 and 8 after wounding, while transepidermal water loss (TEWL) rates were measured in wounded areas. RESULTS: TASE accelerated WH both in vivo (40% vs. 22% reduction in wound area, P<0.01) and in vitro (90% vs. 65% reduction in wound area, P<0.01). Moreover, topical applications of TASE upregulated the expression levels of epidermal mRNA for ELOVL4, HMGCoA, SPT, filaggrin, loricrin and involucrin (P<0.05 vs. vehicle-treated controls) on day 3 after wounding. Likewise, TASE significantly lowered TEWL rates in comparison with vehicle alone on day 8 (33.06±2.09 g/(m2·h) vs. 24.60±2.04 g/(m2·h), P<0.01). CONCLUSIONS: Topical applications of TASE stimulated keratinocyte proliferation and formation of epidermal permeability barrier function, leading to acceleration of acute cutaneous WH. Topical products containing TASE could be used to manage acute cutaneous WH.

Cost Effective Use of a Thiosulfinate-Enriched Allium sativum Extract in Combination with Chemotherapy in Colon Cancer.

In this work, we sought to investigate the effects of a thiosulfinate-enriched garlic extract, co-administered with 5-fluorouracil (5-FU) or oxaliplatin chemotherapy, on the viability of colon cancer cells (Caco-2 and HT-29). We also addressed the economic feasibility of a new combined treatment of this thiosulfinate-enriched garlic extract, with oxaliplatin that could reduce the dosage and costs of a monotherapy. The thiosulfinate-enriched garlic extract not only enhanced the impact of 5-FU and oxaliplatin (500 µM) in decreasing Caco-2 and HT-29 viability, but also showed a higher effect than standard 5-FU and oxaliplatin chemotherapy as anti-cancer agents. These results provided evidences for the combination of lyophilized garlic extract and 5-FU or oxaliplatin as a novel chemotherapy regimen in colon cancer cells that may also reduce the clinical therapy costs.

Identification of a stemness-related gene panel associated with BET inhibition in triple negative breast cancer.

PURPOSE: Triple negative breast cancers (TNBCs) are enriched in cells bearing stem-like features, i.e., cancer stem cells (CSCs), which underlie cancer progression. Thus, targeting stemness may be an interesting treatment approach. The epigenetic machinery is crucial for maintaining the stemness phenotype. Bromodomain and extra-terminal domain (BET) epigenetic reader family members are emerging as novel targets for cancer therapy, and have already shown preclinical effects in breast cancer. Here, we aimed to evaluate the effect of the BET inhibitor JQ1 on stemness in TNBC. METHODS: Transcriptomic, functional annotation and qRT-PCR studies were performed on JQ1-exposed TNBC cells in culture. The results obtained were confirmed in spheroids and spheroid-derived tumours. In addition, limiting dilution, secondary and tertiary tumour sphere formation, matrigel invasion, immunofluorescence and flow cytometry assays were performed to evaluate the effect of JQ1 on CSC features. For clinical outcome analyses, the online tool Kaplan-Meier Plotter and an integrated response database were used. RESULTS: We found that JQ1 modified the expression of stemness-related genes in two TNBC-derived cell lines, MDA-MB-231 and BT549. Among these changes, the CD44 Antigen/CD24 Antigen (CD44/CD24) ratio and Aldehyde Dehydrogenase 1 Family Member A1 (ALDH1A1) expression level, i.e., both classical stemness markers, were found to be decreased by JQ1. Using a validated spheroid model to mimic the intrinsic characteristics of CSCs, we found that JQ1 decreased surface CD44 expression, inhibited self-renewal and invasion, and induced cell cycle arrest in G0/G1, thereby altering the stemness phenotype. We also found associations between four of the identified stemness genes, Gap Junction Protein Alpha 1 (GJA1), CD24, Epithelial Adhesion Molecule (EPCAM) and SRY-related HMG-box gene 9 (SOX9), and a worse TNBC patient outcome. The expression of another two of the stemness-related genes was found to be decreased by JQ1, i.e., ATP Binding Cassette Subfamily G Member 2 (ABCG2) and RUNX2, and predicted a low response to chemotherapy in TNBC patients, which supports a role for RUNX2 as a potential predictive marker for chemotherapy response in TNBC. CONCLUSIONS: We identified a stemness-related gene panel associated with JQ1 and describe how this inhibitor modifies the stemness landscape in TNBC. Therefore, we propose a novel role for JQ1 as a stemness-targeting drug. Loss of the stem cell phenotype via JQ1 treatment could lead to less aggressive and more chemo-sensitive tumours, reflecting a better patient prognosis. Thus, the identified gene panel may be of interest for the clinical management of patients with aggressive TNBC.

Functional transcriptomic annotation and protein-protein interaction analysis identify EZH2 and UBE2C as key upregulated proteins in ovarian cancer.

Although early stage ovarian cancer is in most cases a curable disease, some patients relapse even with appropriate adjuvant treatment. Therefore, the identification of patient and tumor characteristics to better stratify risk and guide rational drug development is desirable. Using transcriptomic functional annotation followed by protein-protein interacting (PPI) network analyses, we identified functions that were upregulated and associated with detrimental outcome in patients with early stage ovarian cancer. Some of the identified functions included cell cycle, cell division, signal transduction/protein modification, cellular response to extracellular stimuli or transcription regulation, among others. Genes within these functions included AURKA, AURKB, CDK1, BIRC5, or CHEK1 among others. Of note, the histone-lysine N-methyltransferase (EZH2) and the ubiquitin-conjugating enzyme E2C (UBE2C) genes were found to be upregulated and amplified in 10% and 6% of tumors, respectively. Of note, EZH2 and UBE2C were identified as principal interacting proteins of druggable networks. In conclusion, we describe a set of genes overexpressed in ovarian cancer with potential for therapeutic intervention including EZH2 and UBE2C.

Functional transcriptomic annotation and protein-protein interaction network analysis identify NEK2, BIRC5, and TOP2A as potential targets in obese patients with luminal A breast cancer.

PURPOSE: Although obesity is a risk factor for breast cancer, little effort has been made in the identification of druggable molecular alterations in obese-breast cancer patients. Tumors are controlled by their surrounding microenvironment, in which the adipose tissue is a main component. In this work, we intended to describe molecular alterations at a transcriptomic and protein-protein interaction (PPI) level between obese and non-obese patients. METHODS AND RESULTS: Gene expression data of 269 primary breast tumors were compared between normal-weight (BMI < 25, n = 130) and obese (IMC > 30, n = 139) patients. No significant differences were found for the global breast cancer population. However, within the luminal A subtype, upregulation of 81 genes was observed in the obese group (FC ≥ 1.4). Next, we explored the association of these genes with patient outcome, observing that 39 were linked with detrimental outcome. Their PPI map formed highly compact cluster and functional annotation analyses showed that cell cycle, cell proliferation, cell differentiation, and cellular response to extracellular stimuli were the more altered functions. Combined analyses of genes within the described functions are correlated with poor outcome. PPI network analyses for each function were to search for druggable opportunities. We identified 16 potentially druggable candidates. Among them, NEK2, BIRC5, and TOP2A were also found to be amplified in breast cancer, suggesting that they could act as strategic players in the obese-deregulated transcriptome. CONCLUSION: In summary, our in silico analysis describes molecular alterations of luminal A tumors and proposes a druggable PPI network in obese patients with potential for translation to the clinical practice.

Synthetic Lethality Interaction Between Aurora Kinases and CHEK1 Inhibitors in Ovarian Cancer.

Ovarian cancer is characterized by frequent mutations at TP53. These tumors also harbor germline mutations at homologous recombination repair genes, so they rely on DNA-damage checkpoint proteins, like the checkpoint kinase 1 (CHEK1) to induce G2 arrest. In our study, by using an in silico approach, we identified a synthetic lethality interaction between CHEK1 and mitotic aurora kinase A (AURKA) inhibitors. Gene expression analyses were used for the identification of relevant biological functions. OVCAR3, OVCAR8, IGROV1, and SKOV3 were used for proliferation studies. Alisertib was tested as AURKA inhibitor and LY2603618 as CHEK1 inhibitor. Analyses of cell cycle and intracellular mediators were performed by flow cytometry and Western blot analysis. Impact on stem cell properties was evaluated by flow cytometry analysis of surface markers and sphere formation assays. Gene expression analyses followed by functional annotation identified a series of deregulated genes that belonged to cell cycle, including AURKA/B, TTK kinase, and CHEK1. AURKA and CHEK1 were amplified in 8.7% and 3.9% of ovarian cancers, respectively. AURKA and CHEK1 inhibitors showed a synergistic interaction in different cellular models. Combination of alisertib and LY2603618 triggered apoptosis, reduced the stem cell population, and increased the effect of taxanes and platinum compounds. Finally, expression of AURKA and CHEK1 was linked with detrimental outcome in patients. Our data describe a synthetic lethality interaction between CHEK1 and AURKA inhibitors with potential translation to the clinical setting. Mol Cancer Ther; 16(11); 2552-62. ©2017 AACR.

Transcriptomic immunologic signature associated with favorable clinical outcome in basal-like breast tumors.

BACKGROUND: Most patients with early stage triple negative breast cancer (TNBC) receive adjuvant chemotherapy. Activation of the immune system is associated with tumor response and may help identify TNBC with favorable outcome. METHODS: Gene expression data were obtained from the GEO Dataset GDS2250/GSE3744. Affymetrix CEL files were downloaded and analyzed with Affymetrix Transcriptome Analysis Console 3.0. Functional genomics was implemented with David Bioinformatics Resources 6.8. Data contained at Oncomine were used to identify genes upregulated in basal-like cancer compared to normal breast tissue. Data contained at cBioportal were used to assess for molecular alterations. The KMPlotter online tool, METABRIC and GSE25066 datasets were used to associate gene signatures with clinical outcome. RESULTS: 1564 upregulated genes were identified as differentially expressed between normal and basal-like tumors. Of these, 16 genes associated with immune function were linked with clinical outcome. HLA-C, HLA-F, HLA-G and TIGIT were associated with both improved relapse-free survival (RFS) and overall survival (OS). The combination of HLA-F/TIGIT and HLA-C/HLA-F/TIGIT showed the most favorable outcome (HR for RFS 0.44, p<0.001; HR for OS 0.22, p<0.001; and HR for RFS 0.46, p<0.001; HR for OS 0.15, p<0.001; respectively). The association of HLA-C/HLA-F with outcome was confirmed using the METABRIC and GSE25066 datasets. No copy number alterations of these genes were identified. CONCLUSION: We describe a gene signature associated with immune function and favorable outcome in basal-like breast cancer. Incorporation of this signature in prospective studies may help to stratify risk of early stage TNBC.

Endothelial secreted factors suppress mitogen deprivation-induced autophagy and apoptosis in glioblastoma stem-like cells.

Rapidly growing and highly vascularized tumors, such as glioblastoma multiforme, contain heterogeneous areas within the tumor mass, some of which are inefficiently supplied with nutrients and oxygen. While the cell death rate is elevated in such zones, tumor cells are still suspected to grow and survive independently of extracellular growth factors. In line with this, glioblastoma stem-like cells (GSCs) are found closely associated with brain vasculature in situ, and as such are most likely in a protected microenvironment. However, the behavior of GSCs under deprived conditions has not been explored in detail. Using a panel of 14 patient-derived GSCs, we report that ex vivo mitogen deprivation impaired self-renewal capability, abolished constitutive activation of the mTor pathway, and impinged on GSC survival via the engagement of autophagic and apoptotic cascades. Moreover, pharmacological inhibition of the mTor pathway recapitulated the mitogen deprivation scenario. In contrast, blocking either apoptosis or autophagy, or culturing GSCs with endothelial-secreted factors partly restored mTor pathway activation and rescued GSC survival. Overall, our data suggest that GSCs are addicted to mTor, as their survival and self-renewal are profoundly dependent on this signaling axis. Thus, as mTor governs the fate of GSCs under both deprivation conditions and in the presence of endothelial factors, it could be a key target for therapeutic purposes.

Glioblastoma cell-secreted interleukin-8 induces brain endothelial cell permeability via CXCR2.

Glioblastoma constitutes the most aggressive and deadly of brain tumors. As yet, both conventional and molecular-based therapies have met with limited success in treatment of this cancer. Among other explanations, the heterogeneity of glioblastoma and the associated microenvironment contribute to its development, as well as resistance and recurrence in response to treatments. Increased vascularity suggests that tumor angiogenesis plays an important role in glioblastoma progression. However, the molecular crosstalk between endothelial and glioblastoma cells requires further investigation. To examine the effects of glioblastoma-derived signals on endothelial homeostasis, glioblastoma cell secretions were collected and used to treat brain endothelial cells. Here, we present evidence that the glioblastoma secretome provides pro-angiogenic signals sufficient to disrupt VE-cadherin-mediated cell-cell junctions and promote endothelial permeability in brain microvascular endothelial cells. An unbiased angiogenesis-specific antibody array screen identified the chemokine, interleukin-8, which was further demonstrated to function as a key factor involved in glioblastoma-induced permeability, mediated through its receptor CXCR2 on brain endothelia. This underappreciated interface between glioblastoma cells and associated endothelium may inspire the development of novel therapeutic strategies to induce tumor regression by preventing vascular permeability and inhibiting angiogenesis.

Semaphorin 3A elevates endothelial cell permeability through PP2A inactivation.

VE-cadherin-mediated cell-cell junction weakening increases paracellular permeability in response to both angiogenic and inflammatory stimuli. Although Semaphorin 3A has emerged as one of the few known anti-angiogenic factors to exhibit pro-permeability activity, little is known about how it triggers vascular leakage. Here we report that Semaphorin 3A induced VE-cadherin serine phosphorylation and internalisation, cell-cell junction destabilisation, and loss of barrier integrity in brain endothelial cells. In addition, high-grade glioma-isolated tumour-initiating cells were found to secrete Semaphorin 3A, which promoted brain endothelial monolayer permeability. From a mechanistic standpoint, Semaphorin 3A impinged upon the basal activity of the serine phosphatase PP2A and disrupted PP2A interaction with VE-cadherin, leading to cell-cell junction disorganization and increased permeability. Accordingly, both pharmacological inhibition and siRNA-based knockdown of PP2A mimicked Semaphorin 3A effects on VE-cadherin. Hence, local Semaphorin 3A production impacts on the PP2A/VE-cadherin equilibrium and contributes to elevated vascular permeability.

Differential proteomic analysis of human glioblastoma and neural stem cells reveals HDGF as a novel angiogenic secreted factor.

Presence in glioblastomas of cancer cells with normal neural stem cell (NSC) properties, tumor initiating capacity, and resistance to current therapies suggests that glioblastoma stem-like cells (GSCs) play central roles in glioblastoma development. We cultured human GSCs endowed with all features of tumor stem cells, including tumor initiation after xenograft and radio-chemoresistance. We established proteomes from four GSC cultures and their corresponding whole tumor tissues (TTs) and from human NSCs. Two-dimensional difference gel electrophoresis and tandem mass spectrometry revealed a twofold increase of hepatoma-derived growth factor (HDGF) in GSCs as compared to TTs and NSCs. Western blot analysis confirmed HDGF overexpression in GSCs as well as its presence in GSC-conditioned medium, while, in contrast, no HDGF was detected in NSC secretome. At the functional level, GSC-conditioned medium induced migration of human cerebral endothelial cells that can be blocked by anti-HDGF antibodies. In vivo, GSC-conditioned medium induced neoangiogenesis, whereas HDGF-targeting siRNAs abrogated this effect. Altogether, our results identify a novel candidate, by which GSCs can support neoangiogenesis, a high-grade glioma hallmark. Our strategy illustrates the usefulness of comparative proteomic analysis to decipher molecular pathways, which underlie GSC properties.

Secreted factors from brain endothelial cells maintain glioblastoma stem-like cell expansion through the mTOR pathway.

Glioma stem-cells are associated with the brain vasculature. However, the way in which this vascular niche regulates stem-cell renewal and fate remains unclear. Here, we show that factors emanating from brain endothelial cells positively control the expansion of long-term glioblastoma stem-like cells. We find that both pharmacological inhibition of and RNA interference with the mammalian target of rapamycin (mTOR) pathway reduce their spheroid growth. Conversely, the endothelial secretome is sufficient to promote this mTOR-dependent survival. Thus, interfering with endothelial signals might present opportunities to identify treatments that selectively target malignant stem-cell niches.

PAKing up to the endothelium.

Angiogenesis recapitulates the growth of blood vessels that progressively expand and remodel into a highly organized and stereotyped vascular network. During adulthood, endothelial cells that formed the vascular wall retain their plasticity and can be engaged in neo-vascularization in response to physiological stimuli, such as hypoxia, wound healing and tissue repair, ovarian cycle and pregnancy. In addition, numerous human diseases and pathological conditions are characterized by an excessive, uncontrolled and aberrant angiogenesis. The signalling pathways involving the small Rho GTPase, Rac and its downstream effector the p21-activated serine/threonine kinase (PAK) had recently emerged as pleiotropic modulators in these processes. Indeed, Rac and PAK were found to modulate endothelial cell biology, such as sprouting, migration, polarity, proliferation, lumen formation, and maturation. Elucidating the Rac/PAK molecular circuitry will provide essential information for the development of new therapeutic agents designed to normalize the blood vasculature in human diseases.

Modulation of the p38 MAPK (mitogen-activated protein kinase) pathway through Bcr/Abl: implications in the cellular response to Ara-C.

The chimaeric protein Bcr/Abl, the hallmark of chronic myeloid leukaemia, has been connected with several signalling pathways, such as those involving protein kinase B/Akt, JNK (c-Jun N-terminal kinase) or ERKs (extracellular-signal-regulated kinases) 1 and 2. However, no data about the p38 MAPK (mitogen-activated protein kinase) have been reported. Here, we present evidence showing that Bcr/Abl is able to modulate this signalling pathway. Transient transfection experiments indicated that overexpression of Bcr/Abl in 293T cells is able to activate p38 MAPK or induce p73 stabilization, suggesting that c-Abl and Bcr/Abl share some biological substrates. Interestingly, the control exerted by Bcr/Abl on the p38 MAPK pathway was not only mediated by the tyrosine kinase activity of Bcr/Abl, as the use of STI571 demonstrated. In fact, Bcr alone was able to induce p38 MAPK activation specifically through MKK3 (MAP kinase kinase 3). Supporting these observations, chronic myeloid leukaemia-derived K562 cells or BaF 3 cells stably transfected with Bcr/Abl showed higher levels of phosphorylated p38 MAPK compared with Bcr/Abl-negative cells. While Bcr/Abl-negative cells activated p38 MAPK in response to Ara-C (1-beta-D-arabinofuranosylcytosine), Bcr/Abl-positive cells were unable to activate p38 MAPK, suggesting that the p38 MAPK pathway is not sensitive to Abl-dependent stimuli in Bcr/Abl-positive cells. Our results demonstrate that the involvement of Bcr/Abl in the p38 MAPK pathway is a key mechanism for explaining resistance to Ara-C, and could provide a clue for new therapeutic approaches based on the use of specific Abl inhibitors.