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
