Helmut Dolznig - Academia.edu (original) (raw)

Papers by Helmut Dolznig

Nature Communications, Jul 17, 2023

Members of the IL-1 pathway are strongly associated with IL1R1 + iCAFs and lower survival in CMS4... more Members of the IL-1 pathway are strongly associated with IL1R1 + iCAFs and lower survival in CMS4 patients To identify CAF subpopulations with a specific IL-1 pathway member expression profile, we further subclustered tumor fibroblasts based on their gene expression profiles (Supplementary Fig. ). Clusters were grouped into myofibroblastic CAFs, or myCAFs (expressing ACTA2, RGS5, CSPG4, and AOC3) and inflammatory CAFs, or iCAFs

Seminars in Cancer Biology, Dec 1, 2015

Human Molecular Genetics, Jun 11, 2010

Human amniotic fluid stem cells (hAFSCs) can be grown in large quantities, have a low risk for tu... more Human amniotic fluid stem cells (hAFSCs) can be grown in large quantities, have a low risk for tumour development and harbour a high differentiation potential. They are a very promising new fetal stem cell type for cell-based therapy approaches and for studying differentiation processes without raising the ethical concerns associated with embryonic stem cells. Recently, a protocol for studies on renal development has been established in which murine embryonic kidneys are dissociated into single-cell suspension and then reaggregated to form organotypic renal structures. Using this approach, we formed chimeric renal structures via mixing murine embryonic kidney cells with monoclonal hAFSCs. We demonstrate here that hAFSCs harbour the potential to contribute to renal tissue formation accompanied by induction of specific renal marker expression. As part of the two kinase complexes mTORC1 and mTORC2, mammalian target of rapamycin (mTOR) is the key component of an important signalling pathway, which is involved in the regulation of differentiation and in the development of a wide variety of human genetic diseases many with characteristic kidney symptoms. Modulating endogenous mTOR activity via specific siRNA approaches revealed that contribution of hAFSCs to renal tissue formation is regulated by mTORC1 and mTORC2. These findings (i) demonstrate renal differentiation potential of hAFSCs, (ii) prove chimeric cultures of mixtures of murine embryonic kidney cells and hAFSCs to be a powerful tool to study the effects of gene knockdowns for renal structure formation and (iii) provide new insights into the role of the mTOR pathway for renal development.

Nature Protocols, May 20, 2010

Optimization of siRNA-mediated gene silencing Using Lipofectamine 2000 transfection reagent, we s... more Optimization of siRNA-mediated gene silencing Using Lipofectamine 2000 transfection reagent, we studied the effects of specific siRNAs targeting the tuberous sclerosis gene product tuberin and the splicing factor SF2/ASF (Box 2) in the transformed immortalized human cell line HeLa and in nontransformed nonimmortalized primary human IMR-90 fibroblasts. In both cell lines, protein knockdown efficiencies were about 95% and the knockdown of specific targets caused expected intracellular effects-upregulation of p70S6K phosphorylation at T389 on tuberin-specific siRNA treatment and induction of apoptosis on ASF/SF2-specific siRNA treatment. The usage of Lipofectamine 2000 allowed the analysis of typical cell cycle-promoting and inhibiting modifications

Allergy, Mar 1, 2009

Smoking is one of the environmental factors thought to have an impact on allergic diseases (1). B... more Smoking is one of the environmental factors thought to have an impact on allergic diseases (1). Both allergic disease and smoking have an extremely high prevalence: it has been estimated that more than 25% of the population of industrialized countries suffer from IgE-mediated allergies, with a continuous tendency to increase (2). The prevalence of smoking is 20.9% in the adult population in the USA (3) and even higher in many European countries (4). Allergic patients suffering from airway disease tend to quit smoking in order to improve airway function (5, 6), but nevertheless there is a huge number of allergic individuals who are also cigarette smokers. Whether cigarette smoking has an impact on the development and course of allergy is a controversial matter. Several epidemiological studies suggest a positive association between smoking and allergy. For example, Background: The association between cigarette smoke exposure and allergic airway disease is a matter for debate. We sought to investigate in an in vitro system whether active smoking reduces the integrity and barrier function of the respiratory epithelium and thus facilitates allergen penetration. Methods: We cultured the human bronchial epithelial cell line 16HBE14o) in a transwell culture system as a surrogate for the intact respiratory epithelium. The cell monolayer was exposed to standardized cigarette smoke extract (CSE). The extent and effects of trans-epithelial allergen penetration were measured using 125 I-labelled purified major respiratory allergens (rBet v 1, rPhl p 5 and rDer p 2) and histamine release experiments. Results: Exposure of cells to concentrations of CSE similar to those found in smokers induced the development of para-cellular gaps and a decrease in transepithelial resistance. CSE exposure induced a more than threefold increase in allergen penetration. Increased subepithelial allergen concentrations provoked a substantial augmentation of histamine release from sensitized basophils. Conclusions: Our results indicate that cigarette smoke is a potent factor capable of reducing the barrier function of the respiratory epithelium for allergens and may contribute to increased allergic inflammation, exacerbation of allergic disease and boosting of IgE memory.

Oncogene, Nov 23, 2009

Human amniotic fluid stem cells (hAFSCs) harbor high proliferative capacity and high differentiat... more Human amniotic fluid stem cells (hAFSCs) harbor high proliferative capacity and high differentiation potential and do not raise the ethical concerns associated with human embryonic stem cells. The formation of threedimensional aggregates known as embryoid bodies (EBs) is the principal step in the differentiation of pluripotent embryonic stem cells. Using c-Kit-positive hAFSC lines, we show here that these stem cells harbor the potential to form EBs. As part of the two kinase complexes, mTORC1 and mTORC2, mammalian target of rapamycin (mTOR) is the key component of an important signaling pathway, which is involved in the regulation of cell proliferation, growth, tumor development and differentiation. Blocking intracellular mTOR activity through the inhibitor rapamycin or through specific small interfering RNA approaches revealed hAFSC EB formation to depend on mTORC1 and mTORC2. These findings demonstrate hAFSCs to be a new and powerful biological system to recapitulate the three-dimensional and tissue level contexts of in vivo development and identify the mTOR pathway to be essential for this process.

Current Biology, Jul 1, 2002

Biochemistry cells. Targeted disruption of Epo or its cognate receptor (EpoR) in the mouse demons... more Biochemistry cells. Targeted disruption of Epo or its cognate receptor (EpoR) in the mouse demonstrated the strict require-2 Institute of Molecular Pathology Vienna Biocenter (VBC) ment of Epo signaling for red cell development. Embryos lacking Epo or EpoR die around embryonic day E12.5 Dr. Bohr-Gasse 7-9 1030 Vienna from failure of definitive erythropoiesis [1, 2]: although the embryos produced apparently normal BFU-E and Austria CFU-E progenitors, these failed to develop into mature, hemoglobinized erythrocytes due to an enhanced rate of cell death [3, 4]. In line with this, expression of Bcl-X L , Summary an antiapoptotic member of the Bcl-2 gene family, was strongly upregulated late during red cell maturation in Background: Erythropoietin (Epo) is required for correct an Epo-dependent fashion [5]. Epo withdrawal caused execution of the erythroid differentiation program. Erythdownregulation of Bcl-X L and Bcl-2 followed by apoptoropoiesis requires Bcl-X L , a major late target of Eposis in Epo-dependent erythroid and lymphoid cell lines receptor signaling. Mice lacking Bcl-X L die around em-[6, 7]. This probably reflects an aberration of established bryonic age E12.5, forming normal erythroid progenitors cell lines, since primary erythroid progenitors do not but lacking functional red cells. Recently, serum-free proliferate with Epo alone and express no Bcl-2 and culture conditions for expansion of murine red cell prolittle Bcl-X L [5, 8]. Furthermore, Bcl-2 knockout mice do genitors were developed, yielding cells capable of in not exhibit an obvious erythroid phenotype [9]. Bcl-X Lvivo-like terminal differentiation into enucleated erythromediated apoptosis protection, however, is required for cytes, in response to Epo/insulin. Here we address erythroid differentiation since full [10] or conditional, hewhether Epo function during terminal maturation inmatopoietic-specific Bcl-X L knockout mice [11] died volves a cytokine-independent "default program," reduring embryogenesis from fetal liver hematopoietic dequiring only apoptosis inhibition through Epo-depenfects or displayed severe anemia. dent upregulation of Bcl-X L. These observations raised the question whether Epo Results: Exogenous expression of Bcl-X L or Bcl-2 in regulates erythroid differentiation solely through apoprimary murine erythroblasts or clonal erythroblast lines ptosis protection via upregulation of Bcl-X L or whether derived from p53 Ϫ/Ϫ mice allowed these cells to undergo additional Epo-dependent target genes are required. terminal erythroid maturation, in the complete absence The available, established erythroid cell lines were unof cytokines. A potential autocrine Epo loop was ruled suitable to address this question, since they require out by respective neutralizing antibodies. Importantly, nonphysiological stimuli to induce maturation and differsustained proliferation of Bcl-X L-expressing immature entiate incompletely. Even when Epo-responsive for erythroblasts still required respective factors (Epo, stem proliferation, such cell lines show aberrant patterns of cell factor [SCF], and the glucocorticoid receptor ligand gene expression during maturation [6, 12, 13]. dexamethasone [Dex]). Epo-independent differentiation Recently, we developed culture conditions for mouse in these Bcl-X L-or Bcl-2-expressing, primary erythroerythroblasts allowing sustained proliferation without blasts was thus triggered by removal of the renewal differentiation (ϭ renewal) in serum-free media. These factors SCF and Dex. This initiated the maturation-specells undergo terminal differentiation into enucleated cific expression cascade of erythroid transcription facerythrocytes in response to the physiological agents tors, followed by differentiation divisions (characterized Epo and Ins [8, 14]. Characterisation of these cells by by a short G1 phase and decrease in cell size), hemogloexpression profiling using cDNA arrays [8] correctly bin accumulation, and enucleation. identified genes known to be induced by Epo during Conclusions: During erythroid maturation, Epo regudifferentiation, such as pim-1 [15] and bcl-X l [5]. lates red cell numbers via apoptosis inhibition, caused In this paper, we demonstrate that Bcl-X L is hardly by Epo-dependent upregulation of the antiapoptotic expressed in renewing primary erythroblasts but is protein Bcl-X L. This allows "default" terminal differentiastrongly upregulated in maturing cells in a strictly Epotion of apoptosis-protected, committed erythroblasts, dependent manner. Retroviral transduction of bcl-X L or independent of any exogenous signals. bcl-2 into primary or immortalized (p53 Ϫ/Ϫ) erythroid progenitors did not alter their dependence on renewal fac

Oncogene, Aug 31, 2009

The tumor-stroma crosstalk is a dynamic process fundamental in tumor development. In hepatocellul... more The tumor-stroma crosstalk is a dynamic process fundamental in tumor development. In hepatocellular carcinoma (HCC), the progression of malignant hepatocytes frequently depends on transforming growth factor (TGF)-β provided by stromal cells. TGF-β induces an epithelial to mesenchymal transition (EMT) of oncogenic Ras-transformed hepatocytes and an upregulation of platelet-derived growth factor (PDGF) signaling. To analyse the influence of the hepatic tumorstroma crosstalk onto tumor growth and progression, we co-injected malignant hepatocytes and myofibroblasts (MFBs). For this, we either used in vitro-activated p19 ARF MFBs or in vivoactivated MFBs derived from physiologically inflamed livers of Mdr2/p19 ARF double-null mice. We show that co-transplantation of MFBs with Ras-transformed hepatocytes strongly enhances tumor growth. Genetic interference with the PDGF signaling decreases tumor cell growth and maintains plasma membrane-located E-cadherin and β-catenin at the tumor-host border, indicating a blockade of hepatocellular EMT. We further generated a collagen gel-based three dimensional HCC model in vitro to monitor the MFB-induced invasion of micro-organoid HCC spheroids. This invasion was diminished after inhibition of TGF-β or PDGF signaling. These data suggest that the TGF-β/PDGF axis is crucial during hepatic tumor-stroma crosstalk, regulating both tumor growth and cancer progression.

European Journal of Cancer, Mar 1, 2018

Background: Anti-PD-1 antibodies have changed the prognosis of metastatic melanoma, improving ove... more Background: Anti-PD-1 antibodies have changed the prognosis of metastatic melanoma, improving overall survival. [1] However, still a proportion of patients is unresponsive to these compounds, indicating the presence of other immunosuppressive mechanisms. Thus, the identification of reliable biomarkers to predict the response to checkpoint blockades is still an unmet need. Recent findings showed a tumorinduced immunosuppressive pathway, in which the extracellular adenosine produced by CD73 (5'-ectonucleotidase) promotes tumor growth by inhibiting effector T-cell functions. [2] The aim of the study was to analyze the levels of CD73 on both circulating CD8 + T cells and myeloid-derived suppressor cells (MDSCs) and their correlation with clinical outcomes of patients. Materials and methods: Blood samples from 52 advanced melanoma patients were collected before nivolumab treatment; blood populations were measured in frozen peripheral blood mononuclear cells (PBMCs) using flow cytometry analysis. The relative expression of CD73 was determined on the CD8+ T cell population alone and in association with PD-1 expression, as well as on MDSCs. Results: Our data demonstrated that median OS for patients with values of CD8+, CD8+/PD-1+ and CD8+/PD-1+/CD73+ over the CUTOFF (26, 7.6 and 2.2, respectively) was lower than OS for patients with values under the CUTOFF (P<0.05, P<0.05 and P<0.005, respectively). In addition, patients with high number of CD8+/PD-1+/CD73+ experienced low PFS (P<0.004). Furthermore, high baseline levels of CD73+ (>2.8 CUTOFF) on MDSCs were negatively correlated with OS and PFS (P<0.02 and P<0.006). Conclusions: Our work indicates that the analysis of CD8+/PD-1+/ CD73+ and MDSCs/CD73+ baseline levels in advanced melanoma patients treated with nivolumab could be associate to treatment outcome. Also, these preliminary results strengthen the therapeutic potential of anti-CD73 inhibitors, which are still in phase I clinical trials, straightening the development of new treatment combinations strategies with other immune checkpoint monoclonal antibodies. Further studies on a larger number of patients are ongoing to confirm the data obtained.

Asian Journal of Andrology, Jan 9, 2012

Male infertility is a major public health issue predominantly caused by defects in germ cell deve... more Male infertility is a major public health issue predominantly caused by defects in germ cell development. In the past, studies on the genetic regulation of spermatogenesis as well as on negative environmental impacts have been hampered by the fact that human germ cell development is intractable to direct analysis in vivo. Compared with model organisms including mice, there are fundamental differences in the molecular processes of human germ cell development. Therefore, an in vitro model mimicking human sperm formation would be an extremely valuable research tool. In the recent past, both human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells have been reported to harbour the potential to differentiate into primordial germ cells and gametes. We here discuss the possibility to use human amniotic fluid stem (AFS) cells as a biological model. Since their discovery in 2003, AFS cells have been characterized to differentiate into cells of all three germ layers, to be genomically stable, to have a high proliferative potential and to be non-tumourigenic. In addition, AFS cells are not subject of ethical concerns. In contrast to iPS cells, AFSs cells do not need ectopic induction of pluripotency, which is often associated with only imperfectly cleared epigenetic memory of the source cells. Since AFS cells can be derived from amniocentesis with disease-causing mutations and can be transfected with high efficiency, they could be used in probing gene functions for spermatogenesis and in screening for male reproductive toxicity.

Biochimica Et Biophysica Acta - Proteins And Proteomics, Apr 1, 1997

Using a combination of centrifugal elutriation and recultivation of synchronised cell populations... more Using a combination of centrifugal elutriation and recultivation of synchronised cell populations we could show that Ž. murine thymidine kinase TK is rapidly degraded during mitosis in polyoma virus-transformed mouse fibroblasts, in parallel to the time-course for loss of cyclin A. Transformation is no prerequisite for the instability phenotype since artificial overexpression of TK under the control of a constitutive promoter in normal mouse fibroblasts also resulted in rapid turnover of TK during mitosis. The decay of TK protein could be partially mimicked in vitro with enzymatically active protein translated in a rabbit reticulocyte lysate: full length polypeptide was lost slightly more rapidly in the presence of G2rM cytosolic extracts than with G1rS preparations. In addition, an enzymatically active C-terminal truncation of 37 amino acids at Gln-196 was completely stable under the conditions tested, confining the instability domain between residues 196 to 233. These experiments also indicated the border for intact TK since translation products up to Tyr-189 or less were completely inactive. This was also confirmed by a mutant TK protein from mouse F9tk y teratocarcinoma cells which harboured a similar deletion. q 1997 Elsevier Science B.V.

Oncology Reports, Sep 20, 2016

Since cancer cells, when grown as spheroids, display drug sensitivity and radiation resistance pa... more Since cancer cells, when grown as spheroids, display drug sensitivity and radiation resistance patterns such as seen in vivo we recently established a three-dimensional (3D) in vitro model recapitulating colorectal cancer (CRC)-triggered lymphatic endothelial cell (LEC)-barrier breaching to study mechanisms of intra-/extravasation. CRC metastasizes not only through lymphatics but also through blood vessels and here we extend the 3D model to the interaction of blood endothelial cells (BECs) with naïve and 5-fluorouracil (5-FU)-resistant CRC CCL227 cells. The 3D model enabled quantifying effects of tumour-derived microRNA200 (miR200) miR200a, miR200b, miR200c, miR141 and miR429 regarding the induction of so-called 'circular chemorepellent-induced defects' (CCIDs) within the BEC-barrier, which resemble gates for tumour transmigration. For this, miR200 precursors were individually transfected and furthermore, the modulation of ZEB family expression was analysed by western blotting. miR200c, miR141 and miR429, which are contained in exosomes from naïve CCL227 cells, downregulated the expression of ZEB2, SNAI and TWIST in BECs. The exosomes of 5-FU-resistant CCL227-RH cells, which are devoid of miR200, accelerated CCID formation in BEC monolayers as compared to exosomes from naïve CCL227 cells. This confirmed the reported role of ZEB2 and SNAI in CRC metastasis and highlighted the active contribution of the stroma in the metastatic process. CCL227 spheroids affected the integrity of BEC and LEC barriers alike, which was in agreement with the observation that CRC metastasizes via blood stream (into the liver) as well as via lymphatics (into lymph nodes and lungs). This further validated the CRC/LEC and CRC/BEC in vitro model to study mechanisms of CRC spreading through vascular systems. Treatment of CCL227-RH cells with the HDAC inhibitors mocetinostat and sulforaphane reduced CCID formation to the level triggered by naïve CCL227 spheroids, however, without significantly influencing miR200 expression in CCL227-RH cells.

Advanced Drug Delivery Reviews, Dec 1, 2014

Anti-cancer drug development is inefficient, mostly due to lack of efficacy in human patients. Th... more Anti-cancer drug development is inefficient, mostly due to lack of efficacy in human patients. The high fail rate is partly due to the lack of predictive models or the inadequate use of existing preclinical test systems. However, progress has been made and preclinical models were improved or newly developed, which all account for basic features of solid cancers, three-dimensionality and heterotypic cell interaction. Here we give an overview of available in vivo and in vitro models of cancer, which meet the criteria of being 3D and mirroring human tumor-stroma interactions. We only focus on drug response models without touching models for pharmacokinetic and dynamic, toxicity or delivery aspects.

Oncotarget, Sep 14, 2011

Besides their putative usage for therapies, stem cells are a promising tool for functional studie... more Besides their putative usage for therapies, stem cells are a promising tool for functional studies of genes involved in human genetic diseases or oncogenesis. For this purpose induced pluripotent stem (iPS) cells can be derived from patients harbouring specific mutations. In contrast to adult stem cells, iPS cells are pluripotent and can efficiently be grown in culture. However, iPS cells are modulated due to the ectopic induction of pluripotency, harbour other somatic mutations accumulated during the life span of the source cells, exhibit only imperfectly cleared epigenetic memory of the source cell, and are often genomically instable. In addition, iPS cells from patients only allow the investigation of mutations, which are not prenatally lethal. Embryonic stem (ES) cells have a high proliferation and differentiation potential, but raise ethical issues. Human embryos, which are not transferred in the course of in vitro fertilization, because of preimplantation genetic diagnosis of a genetic defect, are still rarely donated for the establishment of ES cell lines. In addition, their usage for studies on gene functions for oncogenesis is hampered by the fact the ES cells are already tumorigenic per se. In 2003 amniotic fluid stem (AFS) cells have been discovered, which meanwhile have been demonstrated to harbour the potential to differentiate into cells of all three germ layers. Monoclonal human AFS cell lines derived from amniocenteses have a high proliferative potential, are genomically stable and are not associated with ethical controversies. Worldwide amniocenteses are performed for routine human genetic diagnosis. We here discuss how generation and banking of monoclonal human AFS cell lines with specific chromosomal aberrations or monogenic disease mutations would allow to study the functional consequences of disease causing mutations. In addition, recently a protocol for efficient and highly reproducible siRNA-mediated long-term knockdown of endogenous gene functions in AFS cells was established. Since AFS cells are not tumorigenic, gene modulations not only allow to investigate the role of endogenous genes involved in human genetic diseases but also may help to reveal putative oncogenic gene functions in different biological models, both in vitro and in vivo. This concept is discussed and a "proof of principle", already obtained via modulating genes involved in the mammalian target of rapamycin (mTOR) pathway in AFS cells, is presented.

Oncogene, Jan 30, 2006

The balance between hematopoietic progenitor commitment and self-renewal versus differentiation i... more The balance between hematopoietic progenitor commitment and self-renewal versus differentiation is controlled by various transcriptional regulators cooperating with cytokine receptors. Disruption of this balance is increasingly recognized as important in the development of leukemia,by causing enhanced renewal and differentiation arrest. We studied regulation of renewal versus differentiation in primary murine erythroid progenitors that require cooperation of erythropoietin receptor (EpoR),the receptor tyrosine kinase c-Kit and a transcriptional regulator (glucocorticoid receptor (GR)) for sustained renewal. However, mice defective for GR-(GR dim/dim), EpoR-(EpoR H) or STAT5ab function (Stat5ab −/−) show no severe erythropoiesis defects in vivo. Using primary erythroblast cultures from these mutants, we present genetic evidence that functional GR, EpoR, and Stat5 are essential for erythroblast renewal in vitro. Cells from GR dim/dim , EpoR H , and Stat5ab −/− mice showed enhanced differentiation instead of renewal, causing accumulation of mature cells and gradual proliferation arrest. Stat5ab was additionally required for Epo-induced terminal differentiation: differentiating Stat5ab −/− erythroblasts underwent apoptosis instead of erythrocyte maturation, due to absent induction of the antiapoptotic protein Bcl-X L. This defect could be fully rescued by exogenous Bcl-X L. These data suggest that signaling molecules driving leukemic proliferation may also be essential for prolonged self-renewal of normal erythroid progenitors.

Springer eBooks, 2011

... fibroblasts. Cancer Res 69:369378 Beppu H, Mwizerwa ON, Beppu Y, Dattwyler MP, Lauwers GY, B... more ... fibroblasts. Cancer Res 69:369378 Beppu H, Mwizerwa ON, Beppu Y, Dattwyler MP, Lauwers GY, Bloch KD, Goldstein AM (2008) Stromal inactivation of BMPRII leads to colorectal epithelial overgrowth and polyp formation. ...

Background Pleural mesothelioma (PM) is an aggressive malignancy with poor prognosis. Unlike many... more Background Pleural mesothelioma (PM) is an aggressive malignancy with poor prognosis. Unlike many other cancers, PM is mostly characterized by inactivation of tumor suppressor genes. Its highly malignant nature in absence of tumor driving oncogene mutations indicates an extrinsic supply of stimulating signals by cells of the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are an abundant cell type of the TME and have been shown to drive the progression of several malignancies. The aim of the current study was to isolate and characterize patient-derived mesothelioma-associated fibroblasts (Meso-CAFs), and evaluate their impact on PM cells. Methods Meso-CAFs were isolated from surgical specimens of PM patients and analyzed by array comparative genomic hybridization, transcriptomics and proteomics. Human PM cell lines were retrovirally transduced with GFP. The impact of Meso-CAFs on tumor cell growth, migration, as well as the response to small molecule inhibitors an...

Drug Discovery in Cancer Epigenetics, 2016

Abstract The development of novel anticancer drugs is far from being efficient, mostly due to lac... more Abstract The development of novel anticancer drugs is far from being efficient, mostly due to lack of efficacy in human patients. The 95% attrition rate in the clinic is predominantly owing to the shortage of predictive preclinical models. However, during recent decades in vitro and in vivo preclinical models were engineered, better recapitulating the molecular basis of human cancers, the three-dimensional environment, the cellular heterogeneity or combining the above-mentioned features. Here suitable preclinical in vitro and in vivo cancer models for drug response testing are discussed and advantages and drawbacks of each model are highlighted.

Oncogene

More than 30% of all human cancers are driven by RAS mutations and activating KRAS mutations are ... more More than 30% of all human cancers are driven by RAS mutations and activating KRAS mutations are present in 40% of colorectal cancer (CRC) in the two main CRC subgroups, MSS (Microsatellite Stable) and MSI (Microsatellite Instable). Studies in RAS-driven tumors have shown essential roles of the RAS effectors RAF and specifically of RAF1, which can be dependent or independent of RAF’s ability to activate the MEK/ERK module. In this study, we demonstrate that RAF1, but not its kinase activity, plays a crucial role in the proliferation of both MSI and MSS CRC cell line-derived spheroids and patient-derived organoids, and independently of KRAS mutation status. Moreover, we could define a RAF1 transcriptomic signature which includes genes that contribute to STAT3 activation, and could demonstrate that RAF1 ablation decreases STAT3 phosphorylation in all CRC spheroids tested. The genes involved in STAT3 activation as well as STAT3 targets promoting angiogenesis were also downregulated in ...