Conventional chemotherapy often suffers from a lack of specificity, affecting both normal and cancer cells. Light-activated drugs provide spatial and temporal control over their activity, providing... Show moreConventional chemotherapy often suffers from a lack of specificity, affecting both normal and cancer cells. Light-activated drugs provide spatial and temporal control over their activity, providing a possible solution for this problem. This dissertation describes the synthesis and biological applications of (blue/green/red) light-activated ruthenium polypyridyl drugs as potential prodrugs against cancer. Show less
The field of transition-metal based chemotherapeutics are dominated by derivatives of cisplatin, but a major downside of these platinum based chemotherapeutics is their lack of selectivity... Show moreThe field of transition-metal based chemotherapeutics are dominated by derivatives of cisplatin, but a major downside of these platinum based chemotherapeutics is their lack of selectivity that leads to undesirable side effects. In this work we present alternative strategies such as light-activation with different transition-metals such as ruthenium and palladium that have the potential to be more selective than cisplatin type of drugs. Show less
Intraoperative imaging using near-infrared (NIR) fluorescence is a fast developing imaging modality as it provides real-time visual information during surgery (Chapter 1). The ability to detect... Show moreIntraoperative imaging using near-infrared (NIR) fluorescence is a fast developing imaging modality as it provides real-time visual information during surgery (Chapter 1). The ability to detect lymph nodes and tumours that need to be resected can assist the surgeon to improve surgery by reducing time of the procedure, reducing iatrogenic damage, and improve the number of radical resections. This thesis focuses on the introduction of NIR fluorescence imaging into the clinic. Part 1 of this thesis describes the optimization of NIR fluorescence imaging for sentinel lymph node (SLN) biopsy using the clinically available NIR tracer Indocyanine green (ICG) in various cancer types. Moreover, these studies show both the limitations as the clinical benefit of NIR fluorescence for SLN biopsy. Part 2 describes the use of NIR light for tumour detection. Tissue absorption and scattering in the NIR light spectrum was used for neoadjunvant treatment response monitoring in breast cancer patients. Moreover, NIR fluorescence imaging using NIR contrast agents was used for the intraoperative detection of otherwise difficult to localize liver metastases of colorectal cancer. Show less
Fluorescence-guided surgery (FGS) is an intraoperative imaging technique already introduced and validated in the clinic for sentinel lymph node mapping and biliary imaging. Conjugating a NIR... Show moreFluorescence-guided surgery (FGS) is an intraoperative imaging technique already introduced and validated in the clinic for sentinel lymph node mapping and biliary imaging. Conjugating a NIR-dye to a specific tumor-targeting vehicle dramatically enhances the specificity of this technique. Hence, a powerful synergy can be achieved when fluorescent imaging is combined with nuclear imaging. The (NIR) fluorescent signal aids the surgeon to accurately recognize and resect malignant tissues and detect (nearby) vital structures in real-time during surgery, while its nuclear counterpart can be used to preoperative assess tumor spread and aid in the surgical planning and guidance. Patients may benefit directly from better tumor detection as the surgical status (R0 or R1) is one of the most import parameters for morbidity and patient survival. This thesis focus on the evaluation of potential targets for image-guided surgery applications and describes the preclinical evaluation of novel tracers for (hybrid) image-guided surgery. Show less
This thesis describes the respective contribution of the expression of Tissue factor isoforms full length Tissue Factor (flTF) and alternatively spliced Tissue Factor (asTF) as well as Factor... Show moreThis thesis describes the respective contribution of the expression of Tissue factor isoforms full length Tissue Factor (flTF) and alternatively spliced Tissue Factor (asTF) as well as Factor VII by tumor cells to promote cancer progression. Cohorts of breast, colon, and bone cancer specimens and a multitude of in vitro and in vivo models were used to explore the mechanism behind enhanced cell proliferation and metastasis in in vitro and in vivo models, as well as decreased patient survival associated with TF and FVII expression in cancer patients. Show less
Patients treated for DTC represent a unique clinical population to investigate aspects of thyroid hormone metabolism, thyroid function and related clinical endpoints. Thyroidectomized patients... Show morePatients treated for DTC represent a unique clinical population to investigate aspects of thyroid hormone metabolism, thyroid function and related clinical endpoints. Thyroidectomized patients have no intrinsic T3 production and are completely dependent on peripheral deiodination of exogenous T4. Furthermore, during long-term follow-up thyroid hormone serum levels are frequently measured and the majority of patients have a normal life-span related to high cure rates. Mostly, no autoimmune origin of hypothyroidism is present to take account of, which may have effects on thyroid hormone metabolism itself. It is therefore favorable to investigate the influence of e.g. genetic factors and certain drugs on thyroid metabolism and other endpoints in an athyreotic population.In this thesis several aspects being encountered in the diagnostic process, therapeutic process and follow-up of a thyroid carcinoma are addressed: - Bone morphogenetic protein 7 (BMP7) and downstream proteins as a tool to differentiate between different thyroid pathologies - Thyroid function following hemithyroidectomy - Thyroid dysfunction following treatment with tyrosine kinase inhibitors - Clinical effects of genetic variation in deiodinases - Factors affecting quality of life in patients treated for DTC Show less
In dit proefschrift worden studies besproken naar de rol van de TGF-β signaleringsroute in de tumor micro-omgeving in colorectaal kanker. Deze studies hebben zich voornamelijk gefocust op de rol... Show moreIn dit proefschrift worden studies besproken naar de rol van de TGF-β signaleringsroute in de tumor micro-omgeving in colorectaal kanker. Deze studies hebben zich voornamelijk gefocust op de rol van kanker-geassocieerde fibroblasten (CAFs) in kanker. Wij hebben aangetoond dat een co-receptor voor TGF-β, endoglin, een grote rol speelt in het CAF-gemedieerd uitzaaien van darmkanker en dat de expressie van endoglin op CAFs een prognostische marker is voor metastase-vrije overleving in vroeg stadium darmkankerpatienten. Daarnaast werd een nieuwe muizenstam ontwikkeld om specifiek op fibroblasten endoglin uit te schakelen, zodat de rol hiervan in het ontstaan van darmkanker bestudeerd kon worden in een chemisch geinduceerd model voor darmkanker. Samengevat laten de studies in dit proefschrift zien dat endoglin expressie op CAFs een belangrijke rol speelt in het metastaseren van colorectaalkanker en opent het deuren naar therapeutische toepassingen. Show less
Both copy number losses and homozygosity of chromosome 7 are extremely rare events in many tumor types, indicating that the retention of both the maternal and paternal copies of chromosome 7... Show moreBoth copy number losses and homozygosity of chromosome 7 are extremely rare events in many tumor types, indicating that the retention of both the maternal and paternal copies of chromosome 7 is essential for the tumor cells. This thesis compiles our research into the driving force that is behind the retention of heterozygosity on chromosome 7. The retention of heterozygosity on chromosome 7, we hypothesised, is due to the presence of a set of mono-allelically expressed genes on this chromosome, which are essential for tumor cell survival; so called cell survival genes. Loss of either copy of chromosome 7 would result in a complete loss of expression of those cell survival genes which are exclusively expressed from that particular allele. We have identified 6 imprinted cell survival genes on chromosome 7, that play a role in chromosome 7 retention in thyroid cancer. Additionally, we have analysed allele specific expression on chromosome 7 in a set of novel low passage colorectal cancer cell lines. We also report the extensive characterization, as well as the transcriptome and methylome profiling of these cell lines. Show less
Proteasomes are multi-protein, multi-catalytic complexes responsible for the degradation of 80-90% of the proteins inside eukaryotic cells. Proteasomes contain a cylindrical 20S core particle (CP)... Show moreProteasomes are multi-protein, multi-catalytic complexes responsible for the degradation of 80-90% of the proteins inside eukaryotic cells. Proteasomes contain a cylindrical 20S core particle (CP) and one or two 19S regulatory particles (RP). The constitutive proteasome core particle (cCP), which is expressed in all mammalian tissues, contains three catalytically active subunits, namely β1c, β2c and β5c. Lymphoid cells express another proteasome core particle known as the immunoproteasome (iCP). In iCPs, β1c, β2c and β5c are replaced by β1i, β2i and β5i. The research described in this thesis reports on the development of new subunit-selective inhibitors and activity-based probes, on the development of an assay to simultaneously monitor all cCP and iCP catalytic activities and on the development of a method that reports on CP catalytic active subunit composition. The tools that stem from the work described in this thesis can now be used to unravel the role of each individual catalytic subunit in a chemical genetics setting (selective and (near) complete inhibition of each subunit), and to clarify the role of mCPs, in, for instance, antigen presentation and cancer. Furthermore, these tools could possibly serve as leads in the discovery of agents for future treatment of cancer and autoimmune diseases. Show less
Cancer immunotherapy has shown clinical effectiveness over the recent years, especially in patients with a high mutational load in the tumor. Mutated epitopes, so called 'neo-antigens', are... Show moreCancer immunotherapy has shown clinical effectiveness over the recent years, especially in patients with a high mutational load in the tumor. Mutated epitopes, so called 'neo-antigens', are presented on the tumor and can be regarded as foreign by the immune system. In this thesis, the importance of neo-antigens in the anti-tumor response is explored. First, the characteristics of antigens that can be recognized on human tumors are described, with a specific focus on neo-antigens. Second, technologies are described to systematically analyze neo-antigen specific reactivity in patients with cancer. Third, I show that neo-antigen specific reactivity is a common phenomenon in the CD4 and CD8 T cell compartments of patients with melanoma. Finally, I discuss what the expected value of neo-antigens is in the context of personalized cancer-immunotherapy. Show less
The Reoviridae are a family of viruses with a non-enveloped icosahedral capsid and a segmented double-stranded RNA genome. Prototypes of the mammalian Orthoreoviruses have been isolated from human... Show moreThe Reoviridae are a family of viruses with a non-enveloped icosahedral capsid and a segmented double-stranded RNA genome. Prototypes of the mammalian Orthoreoviruses have been isolated from human respiratory and enteric tracts and are not associated with human disease. One of these, human reovirus type 3 Dearing (T3D), usually serves as a model for the family. In the last decade the mammalian Orthoreoviruses, especially T3D, have been evaluated as oncolytic agents in experimental cancer therapy. This is based on the observation that reoviruses induce cell death in tumor cells, but not in healthy non-transformed cells. Cancer cells have developed all kinds of strategies to escape control of normal regulators in tissue. If the strategy involves evading cell death pathways on which the reovirus relies on for replication or if the expression of the canonical receptor is diminished, the effect of the therapy is severely reduced. To boost the oncolytic potency of reoviruses in tumor cells that resist reovirus infection and replication, we used two strategies; 1) a bioselection procedure to select for reoviurses that can replicate in cells lacking the receptor and 2) genetic modification to insert small transgenes in one of the reovirus dsRNA segments (S1). Show less
Glioblastoma multiforme (GBM) is the most malignant variant of glioma. This tumor does not only display an extremely aggressive, invasive growth pattern, but is also very difficult to treat. With a... Show moreGlioblastoma multiforme (GBM) is the most malignant variant of glioma. This tumor does not only display an extremely aggressive, invasive growth pattern, but is also very difficult to treat. With a two-year survival rate of 40% and a median survival of 12-18 months after treatment, prognosis is poor. Current treatment options are not successful in halting tumor progression and GBM tumors are highly heterogeneous, display all kinds of anti-apoptotic escape routes, suppress the immune system, invade the surrounding parenchyma with unmatched aggressiveness and possess a whole array of tools to rearrange the extra tumoral environment to their advantage. The aim of this thesis is to combine the strengths of gene-therapy and bioluminescence Imaging (BLI) for the development of novel reporter systems in order to study glioma tumor biology and its response to therapeutic compounds. We optimized the currently available BLI luciferases (Gaussia luciferase, Vargula hilgendorfi) and assays (Gluc blood assay, Mycoplasma detection assay). We explored a new multimodal targeted liposome formulation with increased relaxivity for the treatment and imaging of cancer. Finally we combined the newly developed and enhanced reporters to test a new therapeutic combination for the treatment of Glioma (TRAIL, Lanatoside C). Show less
This thesis focus on preclinical validation of novel fluorescent contrast agents for solid tumor imaging (Part I), the clinical introduction of NIR fluorescence sentinel lymph node imaging in... Show moreThis thesis focus on preclinical validation of novel fluorescent contrast agents for solid tumor imaging (Part I), the clinical introduction of NIR fluorescence sentinel lymph node imaging in several cancer types using indocyanine green (Part II) and the clinical translation of NIR fluorescence imaging using clinically available fluorescent contrast agents for solid tumor imaging (Part III) Show less
Cells communicate in multicellular organisms; by secreting and sensing signals, in order to adjust their behavior to the environment. Extracellular signals such as cytokines and growth factors bind... Show moreCells communicate in multicellular organisms; by secreting and sensing signals, in order to adjust their behavior to the environment. Extracellular signals such as cytokines and growth factors bind to cell surface receptors and trigger the activation of multiple protein signal transduction cascades that mediate cellular responses such as proliferation, differentiation, apoptosis and motility. The Mitogen-activated protein kinase (MAPK) family is a group of homologous proteins forming several linear signal transduction pathways. The MAPK family is conserved among eukaryotes and most vertebrates contain at least 14 MAPKs. We are interested in the molecular mechanisms of MAPK signalling that facilitate proper development of the zebrafish embryo. The zebrafish is an excellent model to delineate MAPK associated embryonic processes. The bodyplan is completed within 24hours and within a week most organs are formed. With the current available zebrafish tools molecular mechanisms could be identified and linked to cellular processes and morphological observations. We constructed constitutive active zebrafish Erk2 mutants for identification of new signalling events. We completed expression analysis of all P38 isoforms by expression analysis of the P38_ and P38_ isoforms. We also performed a comparative study between P38_ and Erk2 MAPK in gastrulation. Finally, We addressed the role of P38_ in zebrafish angiogenesis. Show less
Remaining questions and current goals in the treatment of rectal cancer include optimizing staging accuracy, establishing the optimal neoadjuvant strategy to be implemented in the different stages... Show moreRemaining questions and current goals in the treatment of rectal cancer include optimizing staging accuracy, establishing the optimal neoadjuvant strategy to be implemented in the different stages of rectal cancer and possibly leading to the evidence-based introduction of organ sparing and non-operative strategies in selected patients. Furthermore, adverse effects of new multi-modality treatments need to be investigated to properly inform patients. Correlating histopathological response to outcome will provide information on efficacy of new neoadjuvant therapies, factors governing distant metastases and potential consequences of scaling down treatment approaches to avoid surgery. The aim of this thesis, addressing the different modalities, was to evaluate these aspects concerning the multidisciplinary treatment of rectal cancer in general, with the focus on patients with locally advanced rectal cancer in particular Show less
High-grade osteosarcoma is a primary bone tumor with complex genetic alterations, for which targeted therapy is lacking. The aim of this thesis was to use high-throughput molecular data analysis of... Show moreHigh-grade osteosarcoma is a primary bone tumor with complex genetic alterations, for which targeted therapy is lacking. The aim of this thesis was to use high-throughput molecular data analysis of high-grade osteosarcoma specimens and model systems, in order to learn more on osteosarcomagenesis and to find possible ways to inhibit this process. By analyzing different microarray data types using a systems biology approach, genomic instability was identified as an important driver of osteosarcomagenesis. A protective role of macrophages against metastasis of osteosarcoma was detected. In addition, the IR/IGF1R and PI3K/Akt signaling pathways were discovered as potential targets for treatment. This thesis provides the first steps in unraveling the genomic and transcriptomic landscape of high-grade osteosarcoma, and provides a biological rationale for certain new options for adjuvant treatment of this highly genomica lly unstable tumor. Show less
The care for acute complications occurring in cancer patients has changed dramatically in recent decades, not only for direct post-operative care following major cancer surgery, but also for cancer... Show moreThe care for acute complications occurring in cancer patients has changed dramatically in recent decades, not only for direct post-operative care following major cancer surgery, but also for cancer patients in need of organ function replacement due to the manifestation of their malignancy or toxicity of the therapies provided. This thesis studies the epidemiology and outcome of critical illness associated with cancer and/or its treatment in the Netherlands. Chapters 2-5 describe the proportion of cancer patients that requires admission to an Intensive Care Unit (ICU) during the course of their disease and their characteristics and outcome once in the ICU. Chapters 6 and 7 focus on infectious complications in cancer patients. Chapter 8 & 9 contains the summary, general discussion and future perspectives. Show less
Cellular responses to DNA damage are highly variable and strongly depend on the cellular and organismic context. Studying the DNA damage response is crucial for a better understanding of cancer... Show moreCellular responses to DNA damage are highly variable and strongly depend on the cellular and organismic context. Studying the DNA damage response is crucial for a better understanding of cancer formation and ageing as well as genotoxic stress-induced cancer therapy. To do justice to the multifaceted cellular changes, elicited by DNA damage, use of high-throughput techniques and integration with bioinformatics tools is of great value. This thesis summarizes recent advances in the field of systems biology studies of the DNA damage response and furthermore shows integrated approaches of the study of DNA damage response signaling networks in embryonic stem and cancer cells. By integration of transcriptional changes and the phosphorylation and metabolic response of cisplatin-treated embryonic stem cells, with RNAi-based knockdown screens we identify novel DNA damage response signaling networks, linking process such as Wnt signaling, translation arrest or altered metabolic pathways to the cellular response to DNA damage. Furthermore, genes, whose knockdown sensitizes embryonic stem cells to DNA damage-induced killing, are tested in cancer cells of varying genetic backgrounds identifying a small subset of genes, which represent potential drug targets for sensitization of cancer cells. Altogether, our systems approach for studying the DNA damage response identifies novel DNA damage-induced signaling networks and molecules, which modulate survival in the presence of DNA damage, potentially providing new targets for therapeutic intervention or biomarker discovery. Show less
DNA damage, mutations and genomic instability are established driving forces of cancer and other age-related diseases. Mutations in tumor suppressor genes and oncogenes are very frequently found in... Show moreDNA damage, mutations and genomic instability are established driving forces of cancer and other age-related diseases. Mutations in tumor suppressor genes and oncogenes are very frequently found in tumors and genomic instability is the most common enabling characteristic of cancer. Aging is also believed to be enabled, amongst others, by genomic instability. DNA repair pathways, like the nucleotide excision repair (NER) pathway and cell cycle control (e.g. p53-dependent) processes are therefore vital to organisms, since these processes counteract or prevent genomic instability, and are thought to underlie, when affected, aging and age-related diseases like cancer. To unravel the functions, mechanisms and pathways involved in the onset of aging and age-related diseases we have investigated several mouse models deficient in either DNA repair (NER) capacity (Chapter 3, 4), cell cycle control (p53) (Chapter 6) or both (Chapter 5), and compared this to a wild type situation (Chapter 2). The use of mouse models enabled us to investigate cancer and aging in a controlled environment, minimizing possible confounding factors. Additionally, the mouse models can be useful as an alternative tool to identify genotoxic and non-genotoxic carcinogens that can be harmful to the society and the environment (Chapter 5). Show less
