References of "Haan, Serge 50001913"
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See detailIdentifying and targeting cancer-specific metabolism with network-based drug target prediction
Pacheco, Maria UL; Bintener, Tamara Jean Rita UL; Ternes, Dominik UL et al

in EBioMedicine (2019), 43(May 2019), 98-106

Background Metabolic rewiring allows cancer cells to sustain high proliferation rates. Thus, targeting only the cancer-specific cellular metabolism will safeguard healthy tissues. Methods We developed the ... [more ▼]

Background Metabolic rewiring allows cancer cells to sustain high proliferation rates. Thus, targeting only the cancer-specific cellular metabolism will safeguard healthy tissues. Methods We developed the very efficient FASTCORMICS RNA-seq workflow (rFASTCORMICS) to build 10,005 high-resolution metabolic models from the TCGA dataset to capture metabolic rewiring strategies in cancer cells. Colorectal cancer (CRC) was used as a test case for a repurposing workflow based on rFASTCORMICS. Findings Alternative pathways that are not required for proliferation or survival tend to be shut down and, therefore, tumours display cancer-specific essential genes that are significantly enriched for known drug targets. We identified naftifine, ketoconazole, and mimosine as new potential CRC drugs, which were experimentally validated. Interpretation The here presented rFASTCORMICS workflow successfully reconstructs a metabolic model based on RNA-seq data and successfully predicted drug targets and drugs not yet indicted for colorectal cancer. [less ▲]

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See detailIntegrated In Vitro and In Silico Modeling Delineates the Molecular Effects of a Synbiotic Regimen on Colorectal-Cancer-Derived Cells
Greenhalgh, Kacy UL; Ramiro Garcia, Javier UL; Heinken et al

in Cell Reports (2019), 27

By modulating the human gut microbiome, prebiotics and probiotics (combinations of which are called synbiotics) may be used to treat diseases such as colorectal cancer (CRC). Methodological limitations ... [more ▼]

By modulating the human gut microbiome, prebiotics and probiotics (combinations of which are called synbiotics) may be used to treat diseases such as colorectal cancer (CRC). Methodological limitations have prevented determining the potential combina- torial mechanisms of action of such regimens. We expanded our HuMiX gut-on-a-chip model to co-culture CRC-derived epithelial cells with a model probiotic under a simulated prebiotic regimen, and we integrated the multi-omic results with in silico metabolic modeling. In contrast to individual prebi- otic or probiotic treatments, the synbiotic regimen caused downregulation of genes involved in procarci- nogenic pathways and drug resistance, and reduced levels of the oncometabolite lactate. Distinct ratios of organic and short-chain fatty acids were produced during the simulated regimens. Treatment of primary CRC-derived cells with a molecular cocktail reflecting the synbiotic regimen attenuated self-renewal ca- pacity. Our integrated approach demonstrates the potential of modeling for rationally formulating synbi- otics-based treatments in the future. [less ▲]

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See detailThe microRNA-371~373 cluster represses colon cancer initiation and metastatic colonization by inhibiting the TGFBR2/ID1 signaling axis.
Ullmann, Pit UL; Rodriguez, Fabien UL; Schmitz, Martine UL et al

in Cancer research (2018)

The vast majority of colorectal cancer (CRC)-related deaths can be attributed to metastatic spreading of the disease. Therefore, deciphering molecular mechanisms of metastatic dissemination is a key ... [more ▼]

The vast majority of colorectal cancer (CRC)-related deaths can be attributed to metastatic spreading of the disease. Therefore, deciphering molecular mechanisms of metastatic dissemination is a key prerequisite to improve future treatment options. With this aim, we took advantage of different CRC cell lines and recently established primary cultures enriched in colon cancer stem cells (CSCs) - also known as tumor-initiating cells (TICs) - to identify genes and microRNAs (miRNAs) with regulatory functions in CRC progression. We show here that metastasis-derived TICs display increased capacity for self-renewal, transforming growth factor beta (TGF-beta) signaling activity, and reduced expression of the miR-371~373 cluster compared to non-metastatic cultures. TGF-beta receptor 2 (TGFBR2) and aldehyde dehydrogenase A1 (ALDH1A1) were identified as important target genes of the miR-371~373 cluster. In addition, TGFBR2 repression, either by direct knockdown or indirectly via overexpression of the entire miR-371~373 cluster, decreased tumor-initiating potential of TICs. We observed significantly reduced in vitro self-renewal activity as well as lowered tumor-initiation and metastatic outgrowth capacity in vivo following stable overexpression of the miR-371~373 cluster in different colon TIC cultures. Inhibitor of DNA binding 1 (ID1) was affected by both TGFBR2 and miR-371~373 cluster alterations. Functional sphere and tumor formation as well as metastatic dissemination assays validated the link between miR-371~373 and ID1. Altogether, our results establish the miR-371~373/TGFBR2/ID1 signaling axis as a novel regulatory mechanism of TIC self-renewal and metastatic colonization. [less ▲]

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See detailLoss of Myosin Vb in colorectal cancer is a strong prognostic factor for disease recurrence
Letellier, Elisabeth UL; Schmitz, Martine UL; Ginolhac, Aurélien UL et al

in British Journal of Cancer (2017), 117(11), 1689-1701

Background: Selecting the most beneficial treatment regimens for colorectal cancer (CRC) patients remains challenging due to a lack of prognostic markers. Members of the Myosin family, proteins recognized ... [more ▼]

Background: Selecting the most beneficial treatment regimens for colorectal cancer (CRC) patients remains challenging due to a lack of prognostic markers. Members of the Myosin family, proteins recognized to play a major role in trafficking and polarization of cells, have recently been reported to be closely associated with several types of cancer and might thus serve as potential prognostic markers in the context of CRC. Methods: We used a previously established meta-analysis of publicly available gene expression data to analyse the expression of different members of the Myosin V family, namely MYO5A, 5B, and 5C, in CRC. Using laser-microdissected material as well as tissue microarrays from paired human CRC samples, we validated both RNA and protein expression of MYO5B and its known adapter proteins (RAB8A and RAB25) in an independent patient cohort. Finally, we assessed the prognostic value of both MYO5B and its adapter-coupled combinatorial gene expression signatures. Results: The meta-analysis as well as an independent patient cohort study revealed a methylation-independent loss of MYO5B expression in CRC that matched disease progression. Although MYO5B mutations were identified in a small number of patients, these cannot be solely responsible for the common down-regulation observed in CRC patients. Significantly, CRC patients with low MYO5B expression displayed shorter overall, disease- and metastasis-free survival, a trend that was further reinforced when RAB8A expression was also taken into account. Conclusions: Our data identifies MYO5B as a powerful prognostic biomarker in CRC, especially in early stages (stages I and II), which might help stratifying patients with stage II for adjuvant chemotherapy. [less ▲]

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See detailCrosstalk between different family members: IL27 recapitulates IFNγ responses in HCC cells, but is inhibited by IL6-type cytokines
Rolvering, Catherine UL; Zimmer, Andreas; Kozar, Ines UL et al

in BBA Molecular Cell Research (2017)

Interleukin-27 (IL27) is a type-I-cytokine of the IL6/IL12 family predominantly secreted by activated macrophages and dendritic cells. In the liver, IL27 expression was observed to be upregulated in ... [more ▼]

Interleukin-27 (IL27) is a type-I-cytokine of the IL6/IL12 family predominantly secreted by activated macrophages and dendritic cells. In the liver, IL27 expression was observed to be upregulated in patients with hepatitis B, and sera of hepatocellular carcinoma (HCC) patients contain significantly elevated levels of IL27 compared to healthy controls or patients with hepatitis and/or liver cirrhosis. In this study, we show that IL27 induces STAT1 and STAT3 phosphorylation in 5 HCC lines and 3 different types of non-transformed liver cells. We were especially interested in the relevance of the IL27-induced STAT3 activation in liver cells. Thus, we compared the IL27 responses with those induced by IFNγ (STAT1-dominated response) or IL6-type cytokines (IL6, hyper-IL6 (hy-IL6) or OSM) (STAT3-dominated response) by microarray analysis and find that in HCC cells, IL27 induces an IFNγ-like, STAT1-dependent transcriptional response, but we do not find an effective STAT3-dependent response. Validation experiments corroborate the finding from the microarray evaluation. Interestingly, the availability of STAT1 seems critical in the shaping of the IL27 response, as the siRNA knock-down of STAT1 revealed the ability of IL27 to induce the acute-phase protein γ-fibrinogen, a typical IL6 family characteristic. Moreover, we describe a crosstalk between the signaling of IL6-type cytokines and IL27: responses to the gp130-engaging cytokine IL27 (but not those to IFNs) can be inhibited by IL6-type cytokine pre-stimulation, likely by a SOCS3-mediated mechanism. Thus, IL27 recapitulates IFNγ responses in liver cells, but differs from IFNγ by its sensitivity to SOCS3 inhibition. [less ▲]

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See detailTumor-Initiating Cells: a criTICal review of isolation approaches and new challenges in targeting strategies
qureshi-baig, komal; Ullmann, Pit UL; Haan, Serge UL et al

in Molecular Cancer (2017)

Most cancers contain a subpopulation of highly tumorigenic cells, known as cancer stem cells (CSCs) or tumor-initiating cells (TICs). Targeting TICs may be essential to achieve cure, because of their self ... [more ▼]

Most cancers contain a subpopulation of highly tumorigenic cells, known as cancer stem cells (CSCs) or tumor-initiating cells (TICs). Targeting TICs may be essential to achieve cure, because of their self-renewal and tumorigenic properties as well as their resistance to conventional therapies. Despite significant advances in TIC biology, their isolation and identification remain largely disputed and incompletely established. In this review, we discuss the latest developments in isolation and culturing approaches of TICs, with focus on colorectal cancer (CRC). We feature recent findings on TIC-relevant signaling pathways and the metabolic identity of TICs, as well as their current clinical implications. Lastly, we highlight the influence of inter- and intra-tumoral heterogeneity on TIC function and targeting approaches. [less ▲]

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See detailFrom meta-genomics to causality: Understanding the role of colon cancer-associated bacteria in colorectal cancer
Ternes, Dominik UL; Wilmes, Paul UL; Letellier, Elisabeth UL et al

Poster (2017, February 05)

The human gastrointestinal tract is home for trillions of bacteria that influence homeostasis and health in a complex biological system: the gut microbiome. Accumulating evidence suggests that a state of ... [more ▼]

The human gastrointestinal tract is home for trillions of bacteria that influence homeostasis and health in a complex biological system: the gut microbiome. Accumulating evidence suggests that a state of pathological imbalance in the microbiome (dysbiosis) is present in patients suffering from colorectal cancer (CRC). To date, microbiome studies identified specific bacteria being associated with dysbiosis in CRC. Some of these bacteria (e.g. Fusobacteria) directly or indirectly interact with cancer and immune cells of their host. However, current studies only focused on certain microbes in detail, hence, their role in the etiology of the disease remains elusive. Accordingly, my project investigates the role of CRC-associated bacteria in tumor initiation and progression while addressing the question: which and what kind of microbes interact with, favor, or can cause CRC? In a first step, we identified CRC-associated bacteria, enriched at the tumor site of Luxembourgish CRC patients. By using Fusobacterium nucleatum as our study model, we predicted and optimized bacterial growth (media) in silico by using a genome-scale metabolic reconstruction model for a constraint-based modelling approach. Next, we assessed bacterial growth and metabolism in the optimized growth medium by using flow cytometry and mass spectrometry. Finally, we co-cultured the bacteria together with primary patient-derived cultures in the recently developed, microfluidics-based, human-microbial cross-talk model (HuMiX) [1]. As part of our ongoing validations, we infected patient-derived, healthy and cancerous 3D colonic organoids with our bacterial candidate. This workflow enables us to analyze pro-tumorigenic capacities of CRC-associated bacteria on healthy and cancerous colonocytes. It will serve as a promising tool for future analysis of host-microbial interaction mechanisms of various CRC-associated bacteria on a transcriptomic, proteomic, and metabolomic level. [1] Shah P, Fritz JV, Glaab E, Desai MS, Greenhalgh K et al. (2016) A microfluidics-based in vitro model of the gastrointestinal human-microbe interface. Nature communications 7: 11535. [less ▲]

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See detailInsights into ligand stimulation effects on gastro-intestinal stromal tumors signalling.
Bahlawane, Christelle; Schmitz, Martine UL; Letellier, Elisabeth UL et al

in Cell Signal (2017)

Mutations in KIT or PDGFRA are responsible for >85% of gastrointestinal stromal tumors. The introduction of imatinib in the GIST therapy scheme revolutionized the patient outcome. Unfortunately, the ... [more ▼]

Mutations in KIT or PDGFRA are responsible for >85% of gastrointestinal stromal tumors. The introduction of imatinib in the GIST therapy scheme revolutionized the patient outcome. Unfortunately, the therapy allows the disease stabilization instead of curation. Furthermore the resistance to the inhibitor arises in most cases within two first years of therapy. A thorough investigation of the signalling pathways activated by the major PDGFRA and KIT mutants encountered in the GIST landscape allowed to identify striking differences between the two receptor tyrosine kinases. PDGFRA mutants were not responsive to their ligand, PDGFAA, and displayed a high constitutive kinase activity. In contrast, all KIT mutants retained, in addition to their constitutive activation, the ability to be stimulated by their ligand. Kit mutants displayed a lower intrinsic kinase activity relative to PDGFRA mutants, while the KIT Exon 11 deletion mutant exhibited the highest intrinsic kinase activity among KIT mutants. At the transcriptomic level, the MAPK pathway was established as the most prominent activated pathway, which is commonly up-regulated by all PDGFRA and KIT mutants. Inhibition of this pathway, using the MEK inhibitor PD0325901, reduced the proliferation of GIST primary cells at nanomolar concentrations. Altogether, our data demonstrate the high value of MEK inhibitors for combination therapy in GIST treatment and more importantly the interest of evaluating the SCF expression profile in GIST patients presenting KIT mutations. [less ▲]

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See detailData on quantification of signaling pathways activated by KIT and PDGFRA mutants.
Bahlawane, Christelle; Schmitz, Martine UL; Letellier, Elisabeth UL et al

in Data in Brief (2016)

The present data are related to the article entitled "Insights into ligand stimulation effects on gastro-intestinal stromal tumors signaling" (C. Bahlawane, M. Schmitz, E. Letellier, K. Arumugam, N. Nicot ... [more ▼]

The present data are related to the article entitled "Insights into ligand stimulation effects on gastro-intestinal stromal tumors signaling" (C. Bahlawane, M. Schmitz, E. Letellier, K. Arumugam, N. Nicot, P.V. Nazarov, S. Haan, 2016) [1]. Constitutive and ligand-derived signaling pathways mediated by KIT and PDGFRA mutated proteins found in gastrointestinal stromal tumors (GIST) were compared. Expression of mutant proteins was induced by doxycycline in an isogenic background (Hek293 cells). Kit was identified by FACS at the cell surface and found to be quickly degraded or internalized upon SCF stimulation for both Kit Wild type and Kit mutant counterparts. Investigation of the main activated pathways in GIST unraveled a new feature specific for oncogenic KIT mutants, namely their ability to be further activated by Kit ligand, the stem cell factor (scf). We were also able to identify the MAPK pathway as the most prominent target for a common inhibition of PDGFRA and KIT oncogenic signaling. Western blotting and micro-array analysis were applied to analyze the capacities of the mutant to induce an effective STATs response. Among all Kit mutants, only Kit Ex11 deletion mutant was able to elicit an effective STATs response whereas all PDGFRA were able to do so. [less ▲]

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See detailHypoxia-responsive miR-210 promotes self-renewal capacity of colon tumor-initiating cells by repressing ISCU and by inducing lactate production
Ullmann, Pit UL; qureshi-baig, komal; Rodriguez, Fabien UL et al

in Oncotarget (2016)

Low oxygen concentrations (hypoxia) are known to affect the cellular metabolism and have been suggested to regulate a subpopulation of cancer cells with tumorigenic properties, the so-called tumor ... [more ▼]

Low oxygen concentrations (hypoxia) are known to affect the cellular metabolism and have been suggested to regulate a subpopulation of cancer cells with tumorigenic properties, the so-called tumor-initiating cells (TICs). To better understand the mechanism of hypoxia-induced TIC activation, we set out to study the role of hypoxia-responsive miRNAs in recently established colon cancer patientderived TICs. We were able to show that low oxygen concentrations consistently lead to the upregulation of miR-210 in different primary TIC-enriched cultures. Both stable overexpression of miR-210 and knockdown of its target gene ISCU resulted in enhanced TIC self-renewal. We could validate the tumorigenic properties of miR- 210 in in vivo experiments by showing that ectopic expression of miR-210 results in increased tumor incidence. Furthermore, enhanced miR-210 expression correlated with reduced TCA cycle activity and increased lactate levels. Importantly, by blocking lactate production via inhibition of LDHA, we could reverse the promoting effect of miR-210 on self-renewal capacity, thereby emphasizing the regulatory impact of the glycolytic phenotype on colon TIC properties. Finally, by assessing expression levels in patient tissue, we could demonstrate the clinical relevance of the miR-210/ISCU signaling axis for colorectal carcinoma. Taken together, our study highlights the importance of hypoxia-induced miR-210 in the regulation of colon cancer initiation. [less ▲]

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See detailDissecting functions of the N-terminal domain and GAS-site recognition in STAT3
Martincuks, Antons; Fahrenkamp, Dirk; Haan, Serge UL et al

in Cellular Signalling (2016), 28(8), 810-25

Signal transducer and activator of transcription 3 (STAT3) is a ubiquitous transcription factor involved in many biological processes, including hematopoiesis, inflammation and cancer progression ... [more ▼]

Signal transducer and activator of transcription 3 (STAT3) is a ubiquitous transcription factor involved in many biological processes, including hematopoiesis, inflammation and cancer progression. Cytokine-induced gene transcription greatly depends on tyrosine phosphorylation of STAT3 on a single tyrosine residue with subsequent nuclear accumulation and specific DNA sequence (GAS) recognition. In this study, we analyzed the roles of the conserved STAT3 N-terminal domain (NTD) and GAS-element binding ability of STAT3 in nucleocytoplasmic trafficking. Our results demonstrate the nonessential role of GAS-element recognition for both cytokine-induced and basal nuclear import of STAT3. Substitution of five key amino acids within the DNA-binding domain rendered STAT3 unable to bind to GAS-elements while still maintaining the ability for nuclear localization. In turn, deletion of the NTD markedly decreased nuclear accumulation upon IL-6 treatment resulting in a prolonged accumulation of phosphorylated dimers in the cytoplasm, at the same time preserving specific DNA recognition ability of the truncation mutant. Observed defect in nuclear localization could not be explained by flawed importin-α binding, since both wild-type and NTD deletion mutant of STAT3 could precipitate both full-length and autoinhibitory domain (∆ IBB) deletion mutants of importin-α5, as well as ∆ IBB-α3 and ∆ IBB-α7 isoforms independently of IL-6 stimulation. Despite its inability to translocate to the nucleus upon IL-6 stimulation, the NTD lacking mutant still showed nuclear accumulation in resting cells similar to wild-type upon inhibition of nuclear export by leptomycin B. At the same time, blocking the nuclear export pathway could not rescue cytoplasmic trapping of phosphorylated STAT3 molecules without NTD. Moreover, STAT3 mutant with dysfunctional SH2 domain (R609Q) also localized in the nucleus of unstimulated cells after nuclear export blocking, while upon cytokine treatment the subcellular localization of this mutant had not changed. Our findings support the concept that basal nucleocytoplasmic shuttling of STAT3 is different from active cytokine-induced nuclear import and does not require conserved N- or SH2-terminal domains, preformed dimer formation and GAS-element-specific DNA recognition. [less ▲]

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See detailWhat Do We Learn from Spheroid Culture Systems? Insights from Tumorspheres Derived from Primary Colon Cancer Tissue.
Qureshi-Baig, Komal; Ullmann, Pit UL; Rodriguez, Fabien UL et al

in PLoS ONE (2016), 11

Due to their self-renewal and tumorigenic properties, tumor-initiating cells (TICs) have been hypothesized to be important targets for colorectal cancer (CRC). However the study of TICs is hampered by the ... [more ▼]

Due to their self-renewal and tumorigenic properties, tumor-initiating cells (TICs) have been hypothesized to be important targets for colorectal cancer (CRC). However the study of TICs is hampered by the fact that the identification and culturing of TICs is still a subject of extensive debate. Floating three-dimensional spheroid cultures (SC) that grow in serum-free medium supplemented with growth factors are supposed to be enriched in TICs. We generated SC from fresh clinical tumor specimens and compared them to SC isolated from CRC cell-lines as well as to adherent differentiated counterparts. Patient-derived SC display self-renewal capacity and can induce serial transplantable tumors in immuno-deficient mice, which phenotypically resemble the tumor of origin. In addition, the original tumor tissue and established SC retain several similar CRC-relevant mutations. Primary SC express key stemness proteins such as SOX2, OCT4, NANOG and LGR5 and importantly show increased chemoresistance ability compared to their adherent differentiated counterparts and to cell line-derived SC. Strikingly, cells derived from spheroid or adherent differentiating culture conditions displayed similar self-renewal capacity and equally formed tumors in immune-deficient mice, suggesting that self-renewal and tumor-initiation capacity of TICs is not restricted to phenotypically immature spheroid cells, which we describe to be highly plastic and able to reacquire stem-cell traits even after long differentiation processes. Finally, we identified two genes among a sphere gene expression signature that predict disease relapse in CRC patients. Here we propose that SC derived from fresh patient tumor tissue present interesting phenotypic features that may have clinical relevance for chemoresistance and disease relapse and therefore represent a valuable tool to test for new CRC-therapies that overcome drug resistance. [less ▲]

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See detailA Probabilistic Boolean Network Approach for the Analysis of Cancer-Specific Signalling: A Case Study of Deregulated PDGF Signalling in GIST.
Trairatphisan, Panuwat UL; Wiesinger, Monique UL; Bahlawane, Christelle UL et al

in PloS one (2016), 11(5), 0156223

BACKGROUND: Signal transduction networks are increasingly studied with mathematical modelling approaches while each of them is suited for a particular problem. For the contextualisation and analysis of ... [more ▼]

BACKGROUND: Signal transduction networks are increasingly studied with mathematical modelling approaches while each of them is suited for a particular problem. For the contextualisation and analysis of signalling networks with steady-state protein data, we identified probabilistic Boolean network (PBN) as a promising framework which could capture quantitative changes of molecular changes at steady-state with a minimal parameterisation. RESULTS AND CONCLUSION: In our case study, we successfully applied the PBN approach to model and analyse the deregulated Platelet-Derived Growth Factor (PDGF) signalling pathway in Gastrointestinal Stromal Tumour (GIST). We experimentally determined a rich and accurate dataset of steady-state profiles of selected downstream kinases of PDGF-receptor-alpha mutants in combination with inhibitor treatments. Applying the tool optPBN, we fitted a literature-derived candidate network model to the training dataset consisting of single perturbation conditions. Model analysis suggested several important crosstalk interactions. The validity of these predictions was further investigated experimentally pointing to relevant ongoing crosstalk from PI3K to MAPK signalling in tumour cells. The refined model was evaluated with a validation dataset comprising multiple perturbation conditions. The model thereby showed excellent performance allowing to quantitatively predict the combinatorial responses from the individual treatment results in this cancer setting. The established optPBN pipeline is also widely applicable to gain a better understanding of other signalling networks at steady-state in a context-specific fashion. [less ▲]

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See detailSOCS2: physiological and pathological functions.
Letellier, Elisabeth UL; Haan, Serge UL

in Frontiers in bioscience (Elite edition) (2016), 8

Suppressors of cytokine signalling (SOCS) proteins are modulators of cytokine and growth factor signalling whose aberrant regulation has been linked to a variety of inflammatory and neoplastic diseases ... [more ▼]

Suppressors of cytokine signalling (SOCS) proteins are modulators of cytokine and growth factor signalling whose aberrant regulation has been linked to a variety of inflammatory and neoplastic diseases. SOCS proteins are able to act as substrate-recruiting component of E3-ubiquitin ligase complexes and target interacting proteins for degradation. At least some of the family members can also directly inhibit tyrosine kinases such as Janus Kinases (JAK). The most studied family members, CIS, SOCS1, SOCS2 and SOCS3 are important regulators of the JAK-STAT pathway. Here, we focus on SOCS2 and review its biological function as well as its implication in pathological processes. Furthermore, we take advantage of the known crystal structures of SOCS2 to discuss the potential effects of a selection of SOCS2 mutations that were identified in tumour tissues. [less ▲]

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See detailConstitutive activation of oncogenic PDGFRalpha-mutant proteins occurring in GIST patients induces receptor mislocalisation and alters PDGFRalpha signalling characteristics.
Bahlawane, Christelle UL; Eulenfeld, Rene; Wiesinger, Monique UL et al

in Cell Communication and Signaling (2015), 13

BACKGROUND: Gastrointestinal stromal tumours (GIST) are mainly characterised by the presence of activating mutations in either of the two receptor tyrosine kinases c-KIT or platelet-derived growth factor ... [more ▼]

BACKGROUND: Gastrointestinal stromal tumours (GIST) are mainly characterised by the presence of activating mutations in either of the two receptor tyrosine kinases c-KIT or platelet-derived growth factor receptor-alpha (PDGFRalpha). Most mechanistic studies dealing with GIST mutations have focused on c-KIT and far less is known about the signalling characteristics of the mutated PDGFRalpha proteins. Here, we study the signalling capacities and corresponding transcriptional responses of the different PDGFRalpha proteins under comparable genomic conditions. RESULTS: We demonstrate that the constitutive signalling via the oncogenic PDGFRalpha mutants favours a mislocalisation of the receptors and that this modifies the signalling characteristics of the mutated receptors. We show that signalling via the oncogenic PDGFRalpha mutants is not solely characterised by a constitutive activation of the conventional PDGFRalpha signalling pathways. In contrast to wild-type PDGFRalpha signal transduction, the activation of STAT factors (STAT1, STAT3 and STAT5) is an integral part of signalling mediated via mutated PDGF-receptors. Furthermore, this unconventional STAT activation by mutated PDGFRalpha is already initiated in the endoplasmic reticulum whereas the conventional signalling pathways rather require cell surface expression of the receptor. Finally, we demonstrate that the activation of STAT factors also translates into a biologic response as highlighted by the induction of STAT target genes. CONCLUSION: We show that the overall oncogenic response is the result of different signatures emanating from different cellular compartments. Furthermore, STAT mediated responses are an integral part of mutated PDGFRalpha signalling. [less ▲]

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See detailThe oncogenic FIP1L1-PDGFRalpha fusion protein displays skewed signaling properties compared to its wild-type PDGFRalpha counterpart.
Haan, Serge UL; Bahlawane, Christelle UL; Wang, Jiali UL et al

in JAK-STAT (2015), 4(1), 1062596

Aberrant activation of oncogenic kinases is frequently observed in human cancers, but the underlying mechanism and resulting effects on global signaling are incompletely understood. Here, we demonstrate ... [more ▼]

Aberrant activation of oncogenic kinases is frequently observed in human cancers, but the underlying mechanism and resulting effects on global signaling are incompletely understood. Here, we demonstrate that the oncogenic FIP1L1-PDGFRalpha kinase exhibits a significantly different signaling pattern compared to its PDGFRalpha wild type counterpart. Interestingly, the activation of primarily membrane-based signal transduction processes (such as PI3-kinase- and MAP-kinase- pathways) is remarkably shifted toward a prominent activation of STAT factors. This diverging signaling pattern compared to classical PDGF-receptor signaling is partially coupled to the aberrant cytoplasmic localization of the oncogene, since membrane targeting of FIP1L1-PDGFRalpha restores activation of MAPK- and PI3K-pathways. In stark contrast to the classical cytokine-induced STAT activation process, STAT activation by FIP1L1-PDGFRalpha does neither require Janus kinase activity nor Src kinase activity. Furthermore, we investigated the mechanism of STAT5 activation via FIP1L1-PDGFRalpha in more detail and found that STAT5 activation does not involve an SH2-domain-mediated binding mechanism. We thus demonstrate that STAT5 activation occurs via a non-canonical activation mechanism in which STAT5 may be subject to a direct phosphorylation by FIP1L1-PDGFRalpha. [less ▲]

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See detailKapitel 35: Rezeptoren und ihre Signaltransduktion
Heinrich, Peter C.; Haan, Serge UL; Hermanns, Heike M. et al

in Heinrich, Peter C.; Müller, Matthias; Graeve, Lutz (Eds.) Biochemie und Pathobiochemie (2014)

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See detailKapitel 34: Mediatoren
Heinrich, Peter C.; Haan, Serge UL; Hermanns, Heike M. et al

in Heinrich, Peter C.; Müller, Matthias; Graeve, Lutz (Eds.) Biochemie und Pathobiochemie (2014)

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See detailIdentification of SOCS2 and SOCS6 as biomarkers in human colorectal cancer.
Letellier, Elisabeth UL; Schmitz, Martine UL; Baig, Komal UL et al

in British journal of cancer (2014), 111(4), 726-35

BACKGROUND: Over the past years, some members of the family of suppressor of cytokine signalling (SOCS) proteins have emerged as potential tumour suppressors. This study aimed at investigating the ... [more ▼]

BACKGROUND: Over the past years, some members of the family of suppressor of cytokine signalling (SOCS) proteins have emerged as potential tumour suppressors. This study aimed at investigating the clinical significance of SOCS proteins in colorectal carcinoma (CRC). METHODS: We integrated publicly available microarray expression data on CRC in humans, analysed the expression pattern of SOCSs and assessed the predictive power of SOCS2 and SOCS6 for diagnostic purposes by generating receiver operating characteristic curves. Using laser microdissected patient material we assessed SOCS expression on RNA and protein levels as well as their methylation status in an independent CRC patient cohort. Finally, we investigated the prognostic value of SOCS2 and SOCS6. RESULTS: The meta-analysis as well as the independent patient cohort analysis reveal a stage-independent downregulation of SOCS2 and SOCS6 and identify both molecules as diagnostic biomarkers for CRC. We demonstrate a different methylation pattern within the SOCS2 promoter between tumour tissue and normal control tissue in 25% of CRC patients. Furthermore, early CRC stage patients with low expression of SOCS2 display significantly shorter disease-free survival. CONCLUSIONS: Our data offers evidence that SOCS2 and SOCS6 levels are reduced in CRC and may serve as diagnostic biomarkers for CRC patients. [less ▲]

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