EACR-23 Poster Sessions / European Journal of Cancer 50, Suppl. 5 (2014) S23–S242 S87

splicing products of the ING1 gene affect apoptosis and cell senescence, butthe mechanisms are currently unclear.Materials and Methods: Primary diploid fibroblasts were examined for theirpropensity to express different isoforms of ING1, and their response toincreased and decreased levels of ING1 was examined.Results: Expression of the alternatively spliced ING1a tumor suppressorincreases >10-fold during replicative senescence. ING1a overexpressioninhibits growth; induces a large flattened cell morphology and the expressionof senescence-associated b-galactosidase; increases Rb, p16, and cyclinD1 levels; and results in the accumulation of senescence-associatedheterochromatic foci. Here we identify ING1a-regulated genes and find thatING1a induces the expression of a disproportionate number of genes whoseproducts encode proteins involved in endocytosis. Intersectin 2 (ITSN2) is mostaffected by ING1a, being rapidly induced >25-fold. Overexpression of ITSN2independently induces expression of the p16 and p57KIP2 cyclin-dependentkinase inhibitors, which act to block Rb inactivation, acting as downstreameffectors of ING1a. ITSN2 is also induced in normally senescing cells,consistent with elevated levels of ING1a inducing ITSN2 as part of a normalsenescence program. Inhibition of endocytosis or altering the stoichiometryof endosome components such as Rab family members similarly inducessenescence. Knockdown of ITSN2 also blocks the ability of ING1a to induce asenescent phenotype, confirming that ITSN2 is a major transducer of ING1a-induced senescence signaling.Conclusions: These data identify a pathway by which ING1a inducessenescence and indicate that altered endocytosis activates the Rb pathway,subsequently effecting a senescent phenotype. Since ING1a levels increasenaturally near the end of cell replicative activity, the alternative splicing of ING1might represent a regulatory event that subsequently prevents senescing cellsfrom responding normally to mitogenic factors, helping enforce the senescencephenotype believed to block the progression of cancer.No conflict of interest.

364 VHL-dependent changes in global kinome expression in renalcell carcinoma

K. Rantanen1,2, P. Kouvonen1, G.L. Corthals1, P.M. Jaakkola1,2,3. 1TurkuCentre for Biotechnology, University of Turku and Abo Akademi University,Turku, Finland, 2Institute of Biomedicine, Medical School, University of Turku,Finland, 3Department of Oncology and Radiation Therapy, Turku UniversityHospital, Turku, Finland

Background: Renal cell carcinoma (RCC) is the most common form of kidneycancer. Despite the advances in treating RCC, especially at metastatic stagethe prognosis is still quite poor. In RCC, the inactivation of tumor suppressorgene vhl is the most frequent abnormality leading to the stabilization of HIF-1a.The constant activation of HIF-1a is strongly oncogenic and is essential fortumor growth. Therapeutically targeting an inhibiting kinase pathways likemTOR and VEGF by multikinase inhibitors are used for metastatic RCC.However, the biological phenomena behind RCC development is not fullyunderstood.In this study we are aiming to delineate the effect of VHL mutation in globalkinase expression in RCC. We are looking into the kinome variability inwithin VHL-defective RCC as well as between VHL-defective and VHL-restoredcontexts.Materials and Methods: We are utilizing two RCC cell linesnaturally occuringRCC4 with VHL mutation (RCC4 VHL−/−) and RCC with restored VHL(RCCVHL+/+) in order to study the kinome expression regulation in normoxiaand in hypoxia. Targeted mass spectrometry (Selected Reaction Monitoring,SRM) is used to monitor relative kinase abundances related to mutationalstatus of VHL. SRM transitions for selected 77 kinases have been confirmedin a previous study on RCC cell lines and RCC patient tissue.Results and Discussion: Our data suggests a VHL-dependent differentialexpression of several kinases in renal cell carcinoma. Changes in theexpression of kinases such as ROCK, EGFR and MAPK6 of others numberwere observed between RCCVHL−/− and RCCVHL+/+.Conclusions: In this study we are characterising the effect of VHL inactivationon the expression of kinases. For some of these kinases the regulation is VHL-dependent and for others hypoxia VHL-independent regulating factor.No conflict of interest.

365 The interplay between the redox environment, MTH1 and cancer

L. Braeutigam1, R. Fiskesund1, U. Warpman-Berglund1, T. Helleday1.1Science for Life Laboratory, Division of Translational Medicine and ChemicalBiology, Department of Medical Biochemistry and Biophysics, Sweden

Introduction: Redox regulation, the signal transduction through oxidation andreduction processes, is highly important for almost every aspect of cellularfunction. During the recent years it has become increasingly recognizedthat cancer cells have a distinct, deregulated redox profile compared tonon-tumorigenic cells. Targeting those reactive-oxygen species mediatedmechanisms specific for cancer cells might open new avenues for future

therapies. We have exemplified the potential of this reasoning by developinginhibitors against MTH1 which detoxifies oxidized free nucleotides.Material and Methods: We study the relation between the redox environment,MTH1 and cancer using cell culture systems, mice and the zebrafish modelorganism. Amongst others, we challenge cells with different agents that changethe cellular redox profile and use varying oxygen concentration to study itsimpact on drug sensitivity as well as tumorigenic potential.Results and Discussion: Due to the specific redox profile of cancer cells, theirnucleotide pool is highly oxidized. This makes them dependent on MTH1, aNudix-family protein which sanitizes oxidized nucleotides. We have recentlyshown that MTH1 is a new promising target for cancer therapy. Here, wepresent data that shines light on the intricate relation between MTH1, oxygenconcentration and the redox environment of the cancer cell. Moreover, wepresent evidence that MTH1 is connected to distinct oxygen sensing and redoxsignaling pathways and how these connections might be used for future cancertherapy.Conclusion: Cancer cells are characterized by a redox environment thatis clearly distinct from that of non-tumorigenic cells. We are exploiting thecancer-specific redox environment as drug target and are confident that thisknowledge will lead to new therapeutical avenues as exemplified by ourstrategy targeting MTH1.No conflict of interest.

366 The role of tumour derived extracellular matrices on macrophagepolarization

M.L. Pinto1,2, E. Rios3,4, A. Silva1, A.T. Pinto1,5, A.P. Cardoso1,5,D. Nascimento1, P. Pinto do O1,5, F. Carneiro3,4,6, M.B. Barbosa1,2,M.J. Oliveira1,3. 1INEB, Institute of Biomedical Engineering, Oporto,Portugal, 2 ICBAS-Abel Salazar Institute for Biomedical Sciences, Porto,Portugal, 3Department of Pathology and Oncology from Faculty of Medicine,Porto, Portugal, 4Department of Anatomic Pathology, Sao Joao HospitalCenter, Porto, Portugal, 5FEUP-Faculty of Engineering, Porto, Portugal,6 IPATIMUP-Institute of Molecular Pathology and Immunology of the Universityof Porto, Portugal

Introduction: Tumours are highly complex microecosystems composed ofcancer cells, extracellular matrix (ECM) components and other cell types. Themolecular crosstalks established between cancer cells and the surroundingenvironment are crucial for tumour progression. Macrophages have beendescribed as key elements in this process, preventing the spreading ofcancer cells − M1 macrophages − or supporting tumour progression −M2 macrophages. We are particularly interested to elucidate how the ECMand tumour cells contribute to macrophage polarization. Therefore, we arecreating a 3D-organotypic culture mode, by decellularizing human colorectalcancer (CRC) tissue fragments and by repopulating them with monocytes andor/tumour cells, mimicking more closely the natural tumour microecosystem.Materials and Methods: We optimized the decellularization protocol andaccessed its efficiency as well as tissue morphology and architecture bylight microscopy and Scanning Electron Microscopy (SEM). The effect oftissue decellularization on DNA and Glycosaminoglycans (GAGs) contentswere evaluated. These matrices were then repopulated with freshlyisolated monocytes and allowed to differentiate for 7 days. Additionally, wecharacterized through immunohistochemistry (IHC) analysis, CD68, CD163,HLA-DR and calprotectin expression profile of macrophage populations in CRCcases from Sao Joao Hospital Center.Results and Discussion: Deoxyribonucleic acid (DNA) quantification and4′,6-diamidino-2-phenylindole (DAPI) staining confirmed the efficiency of thedecellularization method. SEM analysis allowed the visualization of the ECMfiber meshwork while staining with Hematoxylin-Eosin (HE) and Masson’sTrichrome revealed that decellularized fragments retain the histologicalfeatures of the tissues. Decellularization reduced significantly the GAGScontent in normal and tumours but other ECM components, such aslaminin or fibronectin, are retained. Preliminary results clearly evidenced thatmonocytes are able to colonize decellularized matrices and to differentiate intomacrophages within the fiber network.Conclusion: The decellularization protocol is effective in decellularizingnormal and tumour fragments while retaining, at least partially, tissuearchitecture and composition. Preliminary results on matrices repopulationssuggest that this could be a helpful model to study tumour complexity. Atcompletion of this project we expect to have elucidated the role of tumourcells and of ECM components, derived from the tumour microecosystem, onmacrophage differentiation and polarization, contributing to the design of noveltherapeutic strategies targeting macrophages.No conflict of interest.