A paradoxical tumor suppressor role for the Rac1 exchange factor Vav1 in early cortical T cell acute lymphoblastic leukemia
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE80490 | GEO | 2017/09/30
SECONDARY ACCESSION(S): PRJNA319046
REPOSITORIES: GEO
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Project description:Background: Even though much progress has been made in the understanding of the molecular nature of glioma, the survival rates of patients affected of this tumour have not changed significantly during these years. Thus, a deeper understanding of this malignancy is still needed in order to predict its outcome and improve patient treatment. Here, we report that VAV1, a GDP/GTP exchange factor for Rho/Rac proteins with oncogenic potential that is involved in the regulation of cytoskeletal dynamics and cell migration. Methodology/Principal Findings: VAV1 is overexpressed in 32 patients diagnosed with high-grade glioma. Such overexpression is linked to the parallel upregulation of a number of genes coding for proteins also involved in cell invasion- and migration-related processes. Unexpectedly, immunohistochemical experiments revealed that VAV1 is not expressed in glioma cells. Instead, VAV1 is found in non-tumoral astrocyte-like cells that are located either peritumoraly or perivascularly, suggesting that its expression is linked to synergistic signalling cross-talk between cancer and infiltrating cells. Conclusions/Significance: Interestingly, we show that the pattern of expression of VAV1 is a good prognostic factor to unveil populations of high-grade glioma patients with different survival and progression free survival rates.
2010-09-30 | GSE24072 | GEO
Project description:Rho guanine exchange factors (GEFs), the enzymes that stimulate Rho GTPases, are deemed as potential therapeutic targets owing to their protumorigenic functions. However, the understanding of the spectrum of their pathobiological roles in tumors is still very limited. We report here that the GEF Vav1 unexpectedly possesses tumor-suppressor functions in immature T cells. This function entails the noncatalytic nucleation of complexes between the ubiquitin ligase Cbl-b and the intracellular domain of Notch1 (ICN1) that favors ICN1 ubiquitinylation and degradation. Ablation of Vav1 promotes ICN1 signaling and the development of T cell acute lymphoblastic leukemia (T-ALL). The downregulation of Vav1 is essential for the pathogenesis of human T-ALL of the TLX+ clinical subtype, further underscoring the suppressor role of this pathway.
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2013-03-08 | E-GEOD-36123 | biostudies-arrayexpress
Project description:Analysis of differential gene expression profiles in VAV1-/- versus VAV+/+ BM-macrophages , respectively. A distinct expression profile in VAV1-/- versus VAV1+/+ (wild-type) BM-macrophages allows to resolve molecular mechanisms.
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Project description:The guanosine triphosphatases of the Rho and Rac subfamilies regulate protumorigenic pathways and are activated by guanine nucleotide exchange factors (Rho GEFs), which could be potential targets for anticancer therapies. We report that two Rho GEFs, Vav2 and Vav3, play synergistic roles in breast cancer by sustaining tumor growth, neoangiogenesis, and many of the steps involved in lung-specific metastasis. The involvement of Vav proteins in these processes did not correlate with Rac1 and RhoA activity or cell migration, implying the presence of additional biological programs. Microarray analyses revealed that Vav2 and Vav3 controlled a vast transcriptional program in breast cancer cells through mechanisms that were shared between the two proteins, isoform-specific or synergistic. Furthermore, the abundance of Vav regulated transcripts was modulated by Rac1-dependent and Rac1-independent pathways. This transcriptome encoded therapeutically targetable proteins that played non redundant roles in primary tumorigenesis and lung-specific metastasis, such as integrin-linked kinase (Ilk), the transforming growth factor–b family ligand inhibin bA, cyclooxygenase-2, and the epithelial cell adhesion molecule Tacstd2. It also contained gene signatures that predicted disease outcome in breast cancer patients. These results identify possible targets for treating breast cancer and lung metastases and provide a potential diagnostic tool for clinical use.
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Project description:Mutations in VAV1, a multifunctional signaling protein essential for T lymphocytes, have been recently found in peripheral T cell lymphoma (PTCL) and other tumors. However, their pathobiological significance remains unsettled. Here, we show that these mutations belong to several subclasses according to the spectra of VAV1 signaling branches deregulated by them. These mutations target both known and new regulatory hotspots as well as transitional activation states of the protein. The most frequent VAV1 mutant subclass drives PTCL formation in mice by exacerbating normal VAV1- dependent signaling responses in follicular helper T cells.
2021-09-01 | GSE165006 | GEO
Project description:Vav1, a Rac/Rho guanine nucleotide exchange factor and a critical component of the T cell receptor (TCR) signaling cascade, is rapidly tyrosine phosphorylated in response to T cell activation. Previous studies using Vav1 knockout models have demonstrated its importance in TCR signaling. Although Vav1 has established roles in proliferation, cytokine secretion, Ca2+ responses, and cytoskeletal regulation, its function in the regulation of phosphorylation of TCR components, including the ζ chain, the CD3 δ, ε, γ chains, and the associated kinases Lck, and ZAP-70 is not well established. To obtain a more comprehensive picture of the role of Vav1 in receptor proximal signaling, we performed a wide-scale characterization of Vav1-dependent tyrosine phosphorylation events using quantitative phosphoproteomic analysis of Vav1-deficient T cells across a time course of TCR stimulation. Among the 642 tyrosine phosphorylation sites identified and quantified in cells with or without Vav1, we observed statistically significant alterations in phosphorylation on proteins implicated in canonical actin cytoskeletal rearrangement and cell cycle progression, supporting the previously established role of Vav1 in these functions of TCR signaling. Critically, this study revealed a new role for Vav1 in negative feedback regulation of the phosphorylation of immunoreceptor tyrosine-based activation motifs within the ζ chains, CD3 δ, ε, γ chains, as well as activation sites on the critical T cell tyrosine kinases Itk, Lck, and ZAP-70. Our study also uncovered a previously unappreciated role for Vav1 in crosstalk between the CD28 and TCR signaling pathways.
2016-05-31 | PXD002022 | Pride
Project description:Background: Even though much progress has been made in the understanding of the molecular nature of glioma, the survival rates of patients affected of this tumour have not changed significantly during these years. Thus, a deeper understanding of this malignancy is still needed in order to predict its outcome and improve patient treatment. Here, we report that VAV1, a GDP/GTP exchange factor for Rho/Rac proteins with oncogenic potential that is involved in the regulation of cytoskeletal dynamics and cell migration. Methodology/Principal Findings: VAV1 is overexpressed in 32 patients diagnosed with high-grade glioma. Such overexpression is linked to the parallel upregulation of a number of genes coding for proteins also involved in cell invasion- and migration-related processes. Unexpectedly, immunohistochemical experiments revealed that VAV1 is not expressed in glioma cells. Instead, VAV1 is found in non-tumoral astrocyte-like cells that are located either peritumoraly or perivascularly, suggesting that its expression is linked to synergistic signalling cross-talk between cancer and infiltrating cells. Conclusions/Significance: Interestingly, we show that the pattern of expression of VAV1 is a good prognostic factor to unveil populations of high-grade glioma patients with different survival and progression free survival rates. 1. Oligonucleotide microarray analyses Total RNAs were extracted using the Triazol reagent (Life Technologies, Gaithersburg, MD, USA) and purified with the RNeasy Mini kit (Qiagen, Valencia, CA, USA). The integrity of RNA samples obtained was assessed using the 2100 Bioanalyzer (Agilent, Palo Alto, CA, USA). Double-stranded cDNAs and biotinylated cRNAs were synthesized using a T7-polyT primer and the BioArray RNA labelling Kit (Enzo Farningdale, NY, USA), respectively. Labelled RNAs were then fragmented and hybridised to HU-133A oligonucleotide arrays (Affymetrix, Santa Clara, CA, USA) according to standard Affymetrix protocols. After hybridization and washes, arrays were scanned using the Gene Array Scanner (Affymetrix), and the expression value for each probe set calculated using the MAS 5.0 software (Affymetrix). All examples had a scaling factor lower than threefold and 3’/5’ of GAPDH probe set <2.5. Gene levels were transformed to base two logarithms. A median normalization approach was applied. Only genes with al least three “present” calls across all samples were selected. All these steps were done at the Genomics and Proteomics Unit of the “Centro de Investigación del Cáncer, Salamanca”. 2. Microarray data analyses To visualize clusters of genes with similar expression patterns, we used a hierarchical clustering method (Cluster and TreeView software) based on the average-linkage method with the centred correlation metric [26]. A multidimensional scaling method (BRB Arrays Tools version 3.0) was also utilized by using Euclidean distance criteria [27]. Supervised learning was used to identify genes with statistically significant changes in expression among different classes by using the Significant Analysis of Microarrays (SAM) algorithm [28]. All data were permuted over 100 cycles by using the two-class (unpaired) and multi-class response format. Significant genes were selected based on the lowest false discovery ratio (between 0.6 and 0.9). In addition, nonparametric tests such as Wilcoxon rank sum test and Kruskal-Wallis test to compare more than two unpaired group were also used (SPSS 18, SPSS Inc). 3. Functional annotation of microarray data Probe sets showing significant expression change were functionally annotated and grouped according to biological function criteria using GeneOntology biological process descriptions. The functional analysis to identify the most relevant biological mechanism, pathways and functional categories in gene dada sets was generated using the Ingenuity Pathway software (Ingenuity Systems, Mountain View, CA, USA) available in the web (www.ingenuity.com) [29]. A functional network was considered significant when it fulfilled the following criteria: i) to have a minimal score of 15; ii) to have a minimum of 20 direct functional interactions among the network members. 4. Quantitative reverse transcription-PCR Total RNA was quantified in a RNA 6000 Nano Chip (Agilent Technologies) and quantitative PCR performed using the QuantiTect SYBR Green RT–PCR kit (Qiagen). To quantify VAV1 mRNA levels, we used two different sets of probes: PAIR A (5’-AAC AAC GGG AGG TTC ACC CT-3’ and 5’-GGT CCC TCA TGG CAT CCA-3’) and PAIR B (5’-AGC CAT TGG ACC CTT TCT ACG-3’ and 5’-GCC ATG GAC ATA GGG CTT CA-3’). Amplifications were performed using the iCycler apparatus (Bio-Rad Laboratories, California, USA). Analyses of data were done using the iCycler iQ Optical System Software, version 3.0a (Bio-Rad Laboratories). Primers to GAPDH were used as intersample normalizing controls. Variations in expression of VAV1 mRNA were represented as the mean value of the fold change respect the VAV1 expression levels detected in sample #19209 with both pairs of oligonucleotide primers. 5. Immunohistochemical analyses The VAV1 antibody was generated in rabbits using a synthetic peptide and purified by affinity chromatography in Bustelo’s laboratory. This antibody recognizes VAV1 proteins from humans and mice but it does not recognize other VAV family members (unpublished data). For immunostaining, tissue sections were washed thrice with Xylene and once with 100% ethanol, rehydrated by sequential changes in 80%, 70%, and 50% ethanol and a final incubation in phosphate-buffered saline (PBS). Each rehydrating step involved 3 min incubations with the indicated solutions. Endogenous peroxidases were quenched by the addition of a 3% H2O2 solution in methanol for 30 min at room temperature (RT). Tissue sections were subsequently washed twice with PBS. Antigen retrieval was performed by incubation in 1 mM EDTA for 30 min at 37°C. The slides were washed twice in PBS and blocked in blocking buffer (Zymed, CA, USA) for 30 min at RT. Specimens were then incubated with the primary antibody (1:250 dilution) in blocking buffer. After an 1 hr incubation at 37°C, slides were washed three times in PBS, incubated with a biotinylated secondary antibody for 30 min at 37°C, washed thrice in PBS, incubated with horseradish peroxidase-streptavidin for 30 min at 37°C, washed three times in PBS, and developed using the AEC substrate (Zymed). Slides were then washed twice in water, counterstained with hematoxilin (Zymed), washed again in water, and mounted with GVA (Zymed). Samples were analyzed by light microscopy and images acquired suing an Axiophot imaging system (Zeiss, Munich, Germany). 6. Fluorescence in situ hybridization analyses FISH experiments were carried out in 40 cases of glioblastoma multiforme (grade IV) positive for VAV1 expression. For this purpose, we performed dual-colour FISH analyses with locus-specific probes for centromere 7 (Abbott Molecualr, Des Plaines) exactly as previously described.[30] Polysomies were defined when more than 10% of the nuclei surveyed contained three or more CEP signals (chromosome-specific FISH probes that hybridize to highly repetitive human satellite DNA sequences, usually located near centromeres). 7. Immunohistochemistry and fluorescence in situ hybridization (FISH) in paraffin-embedded tumours Four um sections were cut from routinely processed paraffin blocks and mounted onto glass slides with a charged coating. Sections were dewaxed in Xylene and then rehydrated using increasing concentrations of alcohol before being rinsed briefly in water. Slides were heated 2 min in 1 mM EDTA (pH 9.0) in a microwavable pressure cooker. After antigen retrieval, slides were incubated 1 h at RT in a moist chamber with a primary antibody diluted in PBS supplemented with 10% foetal calf serum. Slides were incubated for 1 h with fluorochrome-conjugated antibodies to the appropriate IgG isotypes in a moist chamber in the dark. Finally, slides were washed thrice in PBS containing 0.5% Tween 20 three before FISH analysis. 8. Degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR) analyses After the staining of tissue sections with VAV1 antibodies (see above), the regions of the tumour were identified, microdissected, and collected using the PALM® microscope system (P.A.L.M. Microlaser Technologies, Munich, Germany). The genomic DNA was extracted as indicated by Isola et al [31] with modifications to small DNA amounts. Those included the resuspension of the microdissected sections in extraction buffer followed by a digestion with proteinase K (0.6 mg/ml). All samples were resuspended in 10 ul of 10 mM Tris-HCl (pH 7.4) and 0.1 mM EDTA. DOP-PCR amplification was performed in two steps. For the first, low-stringency step, 1 ul of sample was added to 4 ul of buffer A (2.5 ul of 600 uM dNTPs (Roche, Pleasanton, CA), 0.5 ul of 10 uM DOP primer 5’-CCGACTCGAGNNNNNNNATGTGG-3’, where N= A, C, G, or T) [32] and 1 ul of 5x Sequenase Reaction Buffer (Amersham, Cleveland, OH). Reactions were performed using 5 cycles of 30ºC for 5 min, 37ºC for 2 min, and 96ºC for 2 min, adding 0.65 units of Sequenase in each 30ºC step. The first phase product was then subjected to the second step usin
2010-09-30 | E-GEOD-24072 | biostudies-arrayexpress
Project description:VAV1 mutations have been recently found in peripheral T cell lymphoma and non-small cell lung cancer. To understand their pathogenic potential, we generated a gene-edited mouse model that expresses a Vav1 mutant protein that recapitulates the signaling alterations present the VAV1 mutant subclass most frequently found in tumors. We could not detect any overt tumorigenic process in those mice. However, the concurrent elimination of the Trp53 tumor suppressor gene in them drives T cell lymphomagenesis. This process represents an exacerbation of the normal functions that wild-type Vav1 plays in follicular helper T cells. We also found that, in combination with an oncogenic Kras mutation, the Vav1 mutant version favors progression of non-small cell lung cancer. These data indicate that VAV1 mutations play critical, although highly cell typespecific roles in tumorigenesis. They also indicate that such functions are contingent on the mutational landscape of the tumors involved.
2022-10-12 | GSE189221 | GEO