ADAMTS1 Supports Endothelial Plasticity of Glioblastoma Cells with Relevance for Glioma Progression.

Gliomas in general and the more advanced glioblastomas (GBM) in particular are the most usual tumors of the central nervous system with poor prognosis. GBM patients develop resistance to distinct therapies, in part due to the existence of tumor cell subpopulations with stem-like properties that participate in trans-differentiation events. Within the complex tumor microenvironment, the involvement of extracellular proteases remains poorly understood. The extracellular protease ADAMTS1 has already been reported to contribute to the plasticity of cancer cells. Accordingly, this basic knowledge and the current availability of massive sequencing data from human gliomas, reinforced the development of this work. We first performed an in silico study of ADAMTS1 and endothelial markers in human gliomas, providing the basis to further assess these molecules in several primary glioblastoma-initiating cells and established GBM cells with the ability to acquire an endothelial-like phenotype. Using a co-culture approach of endothelial and GBM cells, we noticed a relevant function of ADAMTS1 in GBM cells leading the organization of endothelial-like networks and, even more significantly, we found a blockade of the formation of tumor-spheres and a deficient response to hypoxia in the absence of ADAMTS1. Our data support a chief role of this protease modulating the phenotypic plasticity of GBM.

PIM kinases mediate resistance of glioblastoma cells to TRAIL by a p62/SQSTM1-dependent mechanism.

Glioblastoma (GBM) is the most common and aggressive brain tumor and is associated with poor prognosis. GBM cells are frequently resistant to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and finding new combinatorial therapies to sensitize glioma cells to TRAIL remains an important challenge. PIM kinases are serine/threonine kinases that promote cell survival and proliferation and are highly expressed in different tumors. In this work, we studied the role of PIM kinases as regulators of TRAIL sensitivity in GBM cells. Remarkably, PIM inhibition or knockdown facilitated activation by TRAIL of a TRAIL-R2/DR5-mediated and mitochondria-operated apoptotic pathway in TRAIL-resistant GBM cells. The sensitizing effect of PIM knockdown on TRAIL-induced apoptosis was mediated by enhanced caspase-8 recruitment to and activation at the death-inducing signaling complex (DISC). Interestingly, TRAIL-induced internalization of TRAIL-R2/DR5 was significantly reduced in PIM knockdown cells. Phospho-proteome profiling revealed a decreased phosphorylation of p62/SQSTM1 after PIM knockdown. Our results also showed an interaction between p62/SQSTM1 and the DISC that was reverted after PIM knockdown. In line with this, p62/SQSTM1 ablation increased TRAIL-R2/DR5 levels and facilitated TRAIL-induced caspase-8 activation, revealing an inhibitory role of p62/SQSTM1 in TRAIL-mediated apoptosis in GBM. Conversely, upregulation of TRAIL-R2/DR5 upon PIM inhibition and apoptosis induced by the combination of PIM inhibitor and TRAIL were abrogated by a constitutively phosphorylated p62/SQSTM1S332E mutant. Globally, our data represent the first evidence that PIM kinases regulate TRAIL-induced apoptosis in GBM and identify a specific role of p62/SQSTM1Ser332 phosphorylation in the regulation of the extrinsic apoptosis pathway activated by TRAIL.

Homeobox NKX2-3 promotes marginal-zone lymphomagenesis by activating B-cell receptor signalling and shaping lymphocyte dynamics.

NKX2 homeobox family proteins have a role in cancer development. Here we show that NKX2-3 is overexpressed in tumour cells from a subset of patients with marginal-zone lymphomas, but not with other B-cell malignancies. While Nkx2-3-deficient mice exhibit the absence of marginal-zone B cells, transgenic mice with expression of NKX2-3 in B cells show marginal-zone expansion that leads to the development of tumours, faithfully recapitulating the principal clinical and biological features of human marginal-zone lymphomas. NKX2-3 induces B-cell receptor signalling by phosphorylating Lyn/Syk kinases, which in turn activate multiple integrins (LFA-1, VLA-4), adhesion molecules (ICAM-1, MadCAM-1) and the chemokine receptor CXCR4. These molecules enhance migration, polarization and homing of B cells to splenic and extranodal tissues, eventually driving malignant transformation through triggering NF-κB and PI3K-AKT pathways. This study implicates oncogenic NKX2-3 in lymphomagenesis, and provides a valid experimental mouse model for studying the biology and therapy of human marginal-zone B-cell lymphomas.

Anti-cancer cytotoxic effects of multiwalled carbon nanotubes.

Recent research has opened new alternatives to traditional chemotherapy treatments using nanomaterials as cytotoxic agents. Anti-cancer nanomedicines do not require specific target sites on key proteins or genes to kill cancer cells and have radically different mechanisms to interact with the living matter. Among 1D nanomaterials, multiwalled carbon nanotubes (MWCNTs) have the intrinsic ability to bind tubulin and interfere with microtubule dynamics, mimicking the effect of traditional cytotoxic microtubule-binding agents such as paclitaxel (taxol®). Here, we review the cytotoxic properties of MWCNTs and show a direct pro-apoptotic effect of these nanomaterials in vitro in different cancer cell lines and tumor cells obtained from surgical specimens. Understanding the bio-synthetic relationship between MWCNTs and microtubules could serve to improve these nanomaterials to be used as broad spectrum antineoplastic agents in combination to traditional microtubule-binding treatments, thus avoiding drug resistance mechanisms in cancer cells.

Expression and function of toll-like receptors in peripheral blood mononuclear cells of patients with polymyalgia rheumatica and giant cell arteritis.

OBJECTIVE: To investigate the expression and function of the Toll-like receptor (TLR) family in peripheral blood mononuclear cells (PBMCs) of patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). METHODS: The authors analysed 70 patients with PMR, 20 with GCA, and 24 healthy controls (HC). TLR expression was assessed by flow cytometry. TLR function was assessed by stimulating PBMCs with specific ligands. RESULTS: A significantly increased expression of TLR7 in PBMCs of patients with active disease compared with HC was found. Despite increased expression of TLR7, circulating monocytes from patients showed a significantly lower in vitro response to TLR7 agonists. No amino acid substitutions predicted to be functionally damaging were found in TLR7. A normal response to specific TLR7 agonists in patients in complete remission eliminated a genetic defect. TLR expression and function were also affected to some degree in other diseases characterised by a strong acute phase response. CONCLUSION: These data suggest activation of TLR7 during the active phase of PMR and GCA which resolves with complete disease remission. Whether this finding is the consequence of the marked inflammatory process in these disorders or activation by natural ligands remains to be explored.

Prevalencia de la mutación A1555G del gen MTRNR1 en pacientes con hipoacusia postlocutiva sin antecedentes familiares de sordera / Prevalence of the A1555G MTDNA mutation in sporadic hearing-impaired patients without known history of aminoglycoside treatment

Introducción: La mutación A1555G del gen MTRNR1 del ADN mitocondrial es responsable de hipoacusia neurosensorial bilateral no sindrómica que se ve exacerbada por la exposición a aminoglucósidos. El objetivo de nuestro estudio fue determinar la frecuencia de esa mutación en pacientes con hipoacusia neurosensorial, postlocutiva, sin antecedentes familiares de hipoacusia, ni exposición a ototóxicos. Métodos: Se realizó una estudio genético para detectar la mutación A1555G del ADN mitocondrial en los pacientes que consultaron por hipoacusia neurosensorial bilateral postlocutiva, de etiología desconocida, en la consulta de ORL de un hospital comarcal durante 4 años. Resultados: Doscientos diecinueve pacientes fueron estudiados durante dicho período. Dos de ellos (0,9%) eran portadores de la mutación A1555G del ADN mitocondrial en homoplasmia. Ambos tenían una hipoacusia neurosensorial, bilateral y simétrica, moderada para frecuencias medias y severa para altas frecuencias no relacionada con la exposición a ototóxicos. Conclusiones: La mutación A1555G del gen MTDNR1 en pacientes con hipoacusia neurosensorial bilateral postlocutiva en ausencia de antecedentes familiares de hipoacusia por vía materna o desencadenada por aminoglucósidos, es poco frecuente en nuestro medio. Se debe sospechar en aquellos con hipoacusia neurosensorial bilateral con predominio para altas frecuencias menores de 50 años de edad (AU)

Introduction: The A1555G mitochondrial DNA (mtDNA) mutation is responsible for maternally inherited non-syndromic hearing loss that is increased by aminoglycoside exposure. The objective of this study was to ascertain the frequency of the A1555G mutation among patients without family history of hearing loss or known exposition to aminoglycosides. Methods: We screened for the mtDNA A1555G mutation in Spanish patients with sporadic sensorineural hearing impairment without a known family history of hearing loss or aminoglycoside exposition seen at the ENT Department in Sierrallana Hospital (Torrelavega, Cantabria, Spain) over a four-year period. Results: A total of 219 patients with bilateral hearing loss were screened. Two of them (0.9%) had the A1555G mitochondrial DNA mutation. Both patients had a moderate bilateral sensorineural hearing loss for low frequency, and moderate to severe loss for high-frequency. Conclusions: The mtDNA A1555G mutation in patients with sensorineural hearing loss without family history of deafness or aminoglycoside ototoxicity is infrequent in our region. We should suspect this mutation in patients younger than 50 years old, with postlingual bilateral sensorineural hearing loss that is more pronounced at high frequency (AU)

[Prevalence of the A1555G MTDNA mutation in sporadic hearing-impaired patients without known history of aminoglycoside treatment]. / Prevalencia de la mutación A1555G del gen MTRNR1 en pacientes con hipoacusia postlocutiva sin antecedentes familiares de sordera.

INTRODUCTION: The A1555G mitochondrial DNA (mtDNA) mutation is responsible for maternally inherited non-syndromic hearing loss that is increased by aminoglycoside exposure. The objective of this study was to ascertain the frequency of the A1555G mutation among patients without family history of hearing loss or known exposition to aminoglycosides. METHODS: We screened for the mtDNA A1555G mutation in Spanish patients with sporadic sensorineural hearing impairment without a known family history of hearing loss or aminoglycoside exposition seen at the ENT Department in Sierrallana Hospital (Torrelavega, Cantabria, Spain) over a four-year period. RESULTS: A total of 219 patients with bilateral hearing loss were screened. Two of them (0.9%) had the A1555G mitochondrial DNA mutation. Both patients had a moderate bilateral sensorineural hearing loss for low frequency, and moderate to severe loss for high-frequency. CONCLUSIONS: The mtDNA A1555G mutation in patients with sensorineural hearing loss without family history of deafness or aminoglycoside ototoxicity is infrequent in our region. We should suspect this mutation in patients younger than 50 years old, with postlingual bilateral sensorineural hearing loss that is more pronounced at high frequency.

Elevated levels of IL-1beta in Fanconi anaemia group A patients due to a constitutively active phosphoinositide 3-kinase-Akt pathway are capable of promoting tumour cell proliferation.

FA (Fanconi anaemia) is a hereditary disease characterized by congenital malformations, progressive bone marrow failure and an extraordinary elevated predisposition to develop cancer. In the present manuscript we describe an anomalous high level of the proinflammatory cytokine IL-1beta (interleukin-1beta) present in the serum of FA patients. The elevated levels of IL-1beta were completely reverted by transduction of a wild-type copy of the FancA cDNA into FA-A (FA group A) lymphocytes. Although the transcription factor NF-kappaB (nuclear factor-kappaB) is a well established regulator of IL-1beta expression, our experiments did not show any proof of elevated NF-kappaB activity in FA-A cells. However, we found that the overexpression of IL-1beta in FA-A cells is related to a constitutively activated PI3K (phosphoinositide 3-kinase)-Akt pathway in these cells. We provide evidence that the effect of Akt on IL-1beta activation is mediated by the inhibition of GSK3beta (glycogen synthase kinase 3beta). Finally, our data indicate that the levels of IL-1beta produced by FA-A lymphoblasts are enough to promote an activation of the cell cycle in primary glioblastoma progenitor cells. Together, these results demonstrate that the constitutive activation of the PI3K-Akt pathway in FA cells upregulates the expression of IL-1beta through an NF-kappaB-independent mechanism and that this overproduction activates the proliferation of tumour cells.

Deficiency of CARD8 is associated with increased Alzheimer's disease risk in women.

NF-kappaB, a major transcription factor controlling inflammation, is activated in Alzheimer's disease (AD) brains. CARD8 protein has been implicated in the suppression of NF-kappaB activity, but a truncating polymorphism (p.C10X, rs2043211) renders a non-functional CARD8 protein that gives rise to a more active NF-kappaB and an amplification of the inflammatory process. Apolipoprotein E (ApoE) epsilon4 allele, the major genetic risk factor of AD, is associated with hyperactivation of NF-kappaB and enhanced brain inflammation. In a case-control study in 300 AD patients and 300 healthy controls, we examined whether the CARD8 (p.C10X) polymorphism, independently or in concert with the ApoE epsilon4 allele, might predispose to AD. Women, but not men, carrying the CARD8 AA genotype (truncated protein) had a 2.39-fold higher risk of developing AD than subjects with the CARD8 TT genotype (full-length protein). This association with susceptibility to AD was independent of the ApoE epsilon4 allele.

Plexin B1 is downregulated in renal cell carcinomas and modulates cell growth.

Plexins are a family of transmembrane receptors that interact with the repulsive axon guidance molecules (Semaphorins) in neural tissues. In extraneural tissues, plexins are involved in other cellular functions often altered in neoplastic cells, such as adhesion, migration, and apoptosis. Plexin B1 has been implicated in the regulation of Akt, which is an activated pathway in renal cell neoplasms, and only 1 report has emphasized its role as an oncogenic factor. Furthermore, plexin B1 is located in 3p21, which is a chromosomal region deleted frequently in renal cell carcinomas. In accordance with a hypothetical oncogenic role for plexin B1, we have shown by reverse transcription-polymerase chain reaction that plexin B1 is expressed in nonneoplastic renal tissue, and it is severely downregulated in clear cell renal carcinomas. We have also demonstrated by immunohistochemistry on tissue microarrays that plexin B1 protein is absent in more than 80% of renal cell carcinomas (169 in 209 carcinomas examined). Otherwise, all kinds of renal tubules showed strong membrane reactivity. Moreover, when we have induced plexin B1 expression with an expression vector in the renal adenocarcinoma cell line ACHN, a marked reduction in proliferation rate was produced. Altogether, this evidence suggests a possible role for plexin B1 in renal oncogenesis.

Cannabinoid receptors as novel targets for the treatment of melanoma.

Melanoma causes the greatest number of skin cancer-related deaths worldwide. Despite intensive research, prevention and early detection are the only effective measures against melanoma, so new therapeutic strategies are necessary for the management of this devastating disease. Here, we evaluated the efficacy of cannabinoid receptor agonists, a new family of potential antitumoral compounds, at skin melanoma. Human melanomas and melanoma cell lines express CB1 and CB2 cannabinoid receptors. Activation of these receptors decreased growth, proliferation, angiogenesis and metastasis, and increased apoptosis, of melanomas in mice. Cannabinoid antimelanoma activity was independent of the immune status of the animal, could be achieved without overt psychoactive effects and was selective for melanoma cells vs. normal melanocytes. Cannabinoid antiproliferative action on melanoma cells was due, at least in part, to cell cycle arrest at the G1-S transition via inhibition of the prosurvival protein Akt and hypophosphorylation of the pRb retinoblastoma protein tumor suppressor. These findings may contribute to the design of new chemotherapeutic strategies for the management of melanoma.

Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes.

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma.

Breast cancer cells can evade apoptosis-mediated selective killing by a novel small molecule inhibitor of Bcl-2.

Proteins of the Bcl-2 family are key regulators of caspase activation and apoptosis. Some members of this family, notably Bcl-2 and Bcl-x(L), are overexpressed in cancer cells, which have been associated with chemoresistance. We have designed and synthesized a small molecule inhibitor of Bcl-2, named YC137, and studied its role in cancer cells. In vitro studies showed that YC137 inhibits the binding of the Bid BH3 peptide to Bcl-2, thus disrupting an interaction essential for the antiapoptotic activity of Bcl-2. This inhibitor induces apoptosis of hematopoietic progenitors overexpressing Bcl-2 but not Bcl-x(L) and breast cancer cells that express high levels of Bcl-2. On the contrary, a variety of normal primary cells, including CD34(+) progenitors, myoblasts, and peripheral blood mononuclear cells, do not respond to the inhibitor. A breast cancer cell line resistant to YC137 was generated. Analysis of resistant cells revealed a reduced expression of Bcl-2, which correlated with low activation of signal transducer and activator of transcription-3 (Stat3) and reduced expression of the human epidermal growth factor receptor-2 (HER2). Of note, YC137-resistant cells were more sensitive to apoptosis induced by chemotherapy. Because HER2 has not been linked previously to the Stat3-Bcl-2 transcriptional pathway, we additionally confirmed that specific blockade of HER2 in breast cancer cells resulted in down-regulation of Stat3 activity and reduced levels of Bcl-2. Consistently, HER2 blockade led to YC137 resistance. These data provide evidence for the selective killing of tumor cells by YC137 and represent the first example of in vitro selection of cancer cells refractory to a Bcl-2 inhibitor.

Imatinib inhibits proliferation of Ewing tumor cells mediated by the stem cell factor/KIT receptor pathway, and sensitizes cells to vincristine and doxorubicin-induced apoptosis.

PURPOSE AND EXPERIMENTAL DESIGN: The stem cell factor/KIT receptor loop may represent a novel target for molecular-based therapies of Ewing tumor. We analyzed the in vitro impact of KIT blockade by imatinib in Ewing tumor cell lines. RESULTS: KIT expression was detected in 4 of 4 Ewing tumor cell lines and in 49 of 110 patient samples (44.5%) by immunohistochemistry and/or Western blot analysis. KIT expression was stronger in Ewing tumors showing EWS-FLI1 nontype 1 fusions. Despite absence of c-kit mutations, constitutive and ligand-inducible phosphorylation of KIT was found in all tumor cell lines, indicating an active receptor. Treatment with KIT tyrosine kinase inhibitor imatinib (0.5-20 micro M) induced down-regulation of KIT phosphorylation and dose response inhibition of cell proliferation (IC(50), 12-15 micro M). However, imatinib administered alone at doses close to IC(50) for growth inhibition (10 micro M) did not induce a significant increase in apoptosis. We then analyzed if blockade of KIT loop through imatinib (10 micro M) was able to increase the antitumor in vitro effect of doxorubicin (DXR) and vincristine (VCR), drugs usually used in Ewing tumor treatment. Addition of imatinib decreased in 15-20 and 15-36% of the proliferative rate of Ewing tumor cells exposed to DXR and VCR, respectively, and increased in 15 and 30% of the apoptotic rate of Ewing tumor cells exposed to the same drugs. CONCLUSIONS: Inhibition of Ewing tumor cell proliferation by imatinib is mediated through blockade of KIT receptor signaling. Inhibition of KIT increases sensitivity of these cells to DXR and VCR. This study supports a potential role for imatinib in the treatment of Ewing tumor.

Jun N-terminal kinase activity and early growth-response factor-1 gene expression are down-regulated in Fanconi anemia group A lymphoblasts.

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome characterized by cellular sensitivity to genotoxic agents. In recent years, FA proteins have been associated with different molecules involved in signal transduction, which has raised the interest in FA-dependent signaling pathways. Here, we report that the c-Jun N-terminal kinase (JNK) fails to phosphorylate in response to UV radiation and treatment with mitomycin C in FA lymphoblast cells derived from type A patients (FA-A). Furthermore, defective kinase activity seems to be specific for JNK, because extracellular signal-regulated kinase (ERK) responded to the proper stimuli in FA-A cells. We also demonstrate that the early growth-response factor-1 (Egr-1), a JNK downstream target gene that is normally induced by genotoxic stress, is not upregulated in UV-treated FA-A cells. Moreover, FA-A cells are more sensitive to apoptosis than control lymphoblasts. Both JNK and Egr-1 may be part of a pathway triggered by FA proteins, because functional correction of FA-A cells by gene transfer restores, at least in part, JNK activation and Egr-1 expression after UV exposure. Together, our data suggest that activation of JNK and expression of Egr-1 gene in B lymphoblasts mediate a cellular response to genotoxic agents that may be induced by FA proteins.

Fas signaling and blockade of Bcr-Abl kinase induce apoptotic Hrk protein via DREAM inhibition in human leukemia cells.

BACKGROUND AND OBJECTIVES: The apoptotic Bcl-2 family member Hrk is transcriptionally silenced via DREAM in hematopoietic progenitor cell lines, and is specifically induced after growth factor withdrawal. Given that expression of Hrk is sufficient to induce apoptosis, we studied the expression of this apoptotic protein and its regulatory mechanism in human leukemia cells. DESIGN AND METHODS: K562 chronic myeloid leukemia cells were treated with STI571, a Bcr-Abl kinase inhibitor, and the Jurkat T-cell leukemia cell line was incubated with agonistic anti-Fas antibodies. Following treatment, we correlated the expression of Hrk protein with the DNA binding capacity of DREAM, and the induction of apoptosis. RESULTS: We show that treatment of K562 with STI571 blocks the binding of DREAM to the Hrk gene and allows the expression of Hrk, which correlates with the induction of apoptosis. Similarly, treatment of Jurkat cells with agonistic anti-Fas antibodies triggers the expression of Hrk through DREAM inactivation. Interestingly, inhibition of caspases, by culturing Jurkat cells in the presence of z-VAD-fmk, abrogates Fas-mediated hrk expression and apoptosis. Furthermore, in vitro analysis shows that active recombinant caspase-3 releases a fragment from the DREAM protein, suggesting that caspase-3 may be upstream of DREAM. INTERPRETATION AND CONCLUSIONS: These data suggest that apoptosis inducers as diverse as oncoprotein inhibitors and cell death receptor activators trigger Hrk expression via blockade of DREAM in leukemia cells, and this apoptotic pathway may be regulated, at least in some systems, by the proteolytic activity of caspase-3.