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In the last decade there has emerged a new dimension in molecular studies which can be applied to gliomas (brain tumors). Extracellular vesicles (EVs), small structures containing genetic materials, are now known to be produced by glioma cells. These EVs, often many hundreds in number, are released by glioma cells into the blood and fluids surrounding the brain. Originally, these EVs were described as "cell dust in human plasma". There is general consensus that EVs contain gene products including proteins, RNA and DNA. As these products originate from tumor they can be harvested to provide systems that mirror glioma development and progression. My objective has been to study the role of EVs in human blood and other fluids; to identify these EVs and to measure them in order to develop a non-invasive biomarker for detection of glioma. The studies that I have performed have explored the role of these EVs in cancer development and have reviewed the EV-gene products that might be measured to help patients. I then concentrated on developing techniques to find these EVs in small amounts of human fluids and then explored one gene product seen in gliomas. I have worked to improve the way in which we find these EV gene products with the eventual goal of providing diagnosis and care of brain tumor patients without resorting to surgery.There is increasing evidence that extracellular vesicles (EVs) isolated from biofluids will be an important contribution in medicine to develop a non-invasive ways to diagnose and monitor disease. This thesis describes some of the groundwork in development of this new biomarker resource that has so far primarily focused on brain cancer, but the knowledge gained here should have universal applications for all types of diseases.

Huntington’s disease is a heritable neurodegenerative disease with a slow but fatal progression. Affected patients suffer from involuntary movements, changes in behavior and cognitive impairment. The disease is initiated by an expansion of the polyglutamine (polyQ) sequence in the huntingtin protein. Due to this expansion, the protein becomes misfolded and forms intracellular aggregates that are mainly present in the nucleus. The ubiquitin proteasome system is the major degradation system that is present in both the cytoplasm and nucleus of cells. It has been suggested that the ubiquitin proteasome system does not function properly in Huntington’s disease and cannot efficiently clear misfolded huntingtin proteins. In this thesis we explore role of the proteasome in Huntington’s disease. We showed that polyQ peptides that may be generated by the proteasome are peptidase resistant an aggregation prone and we studied the effects of chaperones on these polyQ peptides. Furthermore, we show that proteasomes are able to completely degrade the mutant huntingtin protein and that proteasomes do not become impaired in polyQ aggregates. This raised the question whether we could modulate the proteasome to even improve mutant huntingtin degradation in cells. Finally, we show that changing protesomal activity improves mutant huntingtin degradation. Together these findings contribute to a better understanding of mutant huntingtin processing by proteasomes.

Like all types of cancer, pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic malignancy, is a disease of the genes and the genetic alterations that are involved in the development of PDAC have been under investigation for many years. The research described in this thesis focuses on these genetic alterations and their clinical relevance. In order to provide an overview of the current insights in pancreatic carcinogenesis, the review articles in Chapter 3 and Chapter 4 are included. In Chapter 5, multivariate analysis was conducted investigating the effects on survival of both clinical and histological features of PDAC. The study showed that lymph node ratio

De eiwitten TGF-β en CTGF zijn bij diabetische retinopathie (DR) zijn betrokken bij fibrose (littekenvorming) in de bloedvaten van het netvlies. DR wordt gekenmerkt door schade aan het netvlies door suikerziekte, en is een veel voorkomende oorzaak van slechtziendheid. Robert-Jan van Geest laat bij patiënten zien dat TGF-β en CTGF, in samenhang met andere eiwitten, een rol spelen bij fibrose in verschillende stadia van de oogziekte. Dit kan wellicht leiden tot nieuwe behandelopties voor mensen met DR.

Het proteasoom zorgt voor afbraak van eiwitten. Dat gebeurt in stappen eerst genereert het proteasoom kleine peptiden die peptidases vervolgens verder afbreken tot individuele aminozuren. Een deel wordt gepresenteerd aan het immuunsysteem. Een subgroep daarvan is niet - zoals werd aangenomen - gemaakt door tripeptidyl peptidase II (TPPII) maar door metallopeptidases. Deze bevinding kan implicaties hebben voor het detecteren van kankercellen en cellen die door virussen geïnfecteerd zijn. Raspe onderzocht ook de functie van peptidases bij neurodegeneratieve ziekten als Alzheimer en Huntington die gepaard gaan met ophoping van moeilijk afbreekbare eiwitfragmenten. Bij Huntington bemoeilijkt een lange herhaling van hetzelfde aminozuur de afbraak van die eiwitfragmenten. Raspe vond twee peptidases (PSA en TPPII) die dergelijke ophopingen verminderen. PSA doet dat niet op de gebruikelijke wijze maar door het activeren van een ander opruimmechanisme, autofagie (waarbij de cel zichzelf als het ware opeet).