Aberrant glycosylation is considered to be a hallmark of colorectal cancer (CRC), as demonstrated by various studies. While the N-glycosylation of cell lines and serum has been widely examined, the... Show moreAberrant glycosylation is considered to be a hallmark of colorectal cancer (CRC), as demonstrated by various studies. While the N-glycosylation of cell lines and serum has been widely examined, the analysis of cancer-associated N-glycans from tissues has been hampered by the heterogeneity of tumors and the complexity of N-glycan structures. To overcome these obstacles, we present a study using laser capture microdissection that makes it possible to largely deconvolute distinct N-glycomic signatures originating from different regions of heterogeneous tissues including cancerous, stromal, and healthy mucosa cells. N-glycan alditols were analyzed by means of porous graphitized carbon liquid chromatography-electrospray ionization tandem mass spectrometry, enabling the differentiation and structural characterization of isomeric species. In total, 116 N-glycans were identified that showed profound differences in expression among cancer, stroma, and normal mucosa. In comparison with healthy mucosa, the cancer cells showed an increase in α2-6 sialylation and monoantennary N-glycans, as well as a decrease in bisected N-glycans. Moreover, specific sialylated and (sialyl-)LewisA/X antigen-carrying N-glycans were exclusively expressed in cancers. In comparison with cancer, the stroma showed lower levels of oligomannosidic and monoantennary N-glycans, LewisA/X epitopes, and sulfation, as well as increased expression of (core-)fucosylation and α2-3 sialylation. Our study reveals the distinct N-glycomic profiles of different cell types in CRC and control tissues, proving the necessity of their separate analysis for the discovery of cancer-associated glycans. Show less
Background The diagnostic workup of ovarian tumors in children and adolescents is challenging because preserving fertility, in addition to oncological safety, is of particular importance in this... Show moreBackground The diagnostic workup of ovarian tumors in children and adolescents is challenging because preserving fertility, in addition to oncological safety, is of particular importance in this population. Therefore, a thorough preoperative assessment of ovarian tumors is required. Objective To investigate the diagnostic value of MR imaging in differentiating benign from malignant ovarian tumors in children and adolescents. Materials and methods We conducted a retrospective study of all children and adolescents age Results We included 30 girls who underwent MR imaging for an ovarian tumor. Signs indicative for malignancy were tumors with a diameter >= 8 cm, with areas of contrast enhancement, irregular margins, extracapsular tumor growth, and ascites. All benign and malignant ovarian tumors were correctly identified by the radiologists. Conclusion The diagnostic utility of MR imaging in classifying ovarian tumors in children and adolescents as benign or malignant is promising and might aid in defining the indication for ovarian-sparing versus non-ovarian-sparing surgery. We recommend evaluating these tumors with MR imaging prior to deciding on surgical treatment. Show less
Endoscopic transsphenoidal surgery for pituitary adenomas is a safe and highly effective first-line treatment that is well tolerated by patients. There are many potential complications, and there... Show moreEndoscopic transsphenoidal surgery for pituitary adenomas is a safe and highly effective first-line treatment that is well tolerated by patients. There are many potential complications, and there is a large variation in complexity of surgery. This article presents the philosophy, surgical techniques, and outcomes of a high-volume pituitary adenoma center. Three surgical videos illustrate some procedures. The experience has reinforced the authors' belief that experience and surgical volume are key to high quality of care. Show less
Sghaier, R. ben; Jansen, A.M.L.; Bdioui, A.; Wezel, T. van; Ksiaa, M.; Elgolli, L.; ... ; Morreau, H. 2019
A high colorectal cancer (CRC) incidence is observed in Tunisia, with a relatively high proportion of patients developing CRC before the age of 40. While this suggests a genetic susceptibility,... Show moreA high colorectal cancer (CRC) incidence is observed in Tunisia, with a relatively high proportion of patients developing CRC before the age of 40. While this suggests a genetic susceptibility, only a few Tunisian Lynch Syndrome families have been described. In this study we aimed to identify the underlying genetic cause in 32 patients with early onset CRC and/or a positive family history. Of twenty-four patients' tumor or biopsies could be analyzed with immunohistochemical staining to detect loss of expression of one of the MMR proteins. Ten tumors showed loss of expression, of which one tumor was from a patient where a germline pathogenic MSH2 variant was detected previously with Sanger sequencing. Next generation sequencing of the MMR, POLE and POLD1 genes was performed in leukocyte and tumor DNA of the remaining nine patients, as well as in two patients with MMR-proficient tumors, but with severe family history. In six of 11 patients a germline variant was detected in MLH1 (n=5) or MSH2 (n=1). Two of six patients were from the same family and both were found to carry a novel in-frame MLH1 deletion, predicted to affect MLH1 function. All MLH1 variant carriers had loss of heterozygosity with retention of the variant in the tumors, while a somatic pathogenic variant was detected in the patient with the germline MSH2 variant. Show less
Pathology laboratories throughout the world have compiled large archives of unique collections of tissue specimens. These tissue samples are used for patient diagnostics and research. Novel... Show morePathology laboratories throughout the world have compiled large archives of unique collections of tissue specimens. These tissue samples are used for patient diagnostics and research. Novel molecular insights into alterations in normal cellular function have led to the identification of targets for innovative therapies. Testing for biomarkers combined with molecular pathology has created the potential for __personalized medicine__ and improved diagnosis, treatment and prognosis. New technologies for molecular analysis in molecular tumor diagnostics and research must be developed and implemented to keep pace with the latest insights, resulting in a constant cycle of change. Such translational research can only progress if patient material can be accessed from the archives for further study. The resulting new insights and strategies will eventually be implemented in patient care. This thesis describes three important issues in this cycle of change with a focus on molecular pathology. Tissue preparation, method development and data analysis. Show less
This thesis focuses on alternative antigen presentation in the context of tumors with defects in antigen processing. In chapter 2, we investigate whether the human T-cell repertoire harbors a... Show moreThis thesis focuses on alternative antigen presentation in the context of tumors with defects in antigen processing. In chapter 2, we investigate whether the human T-cell repertoire harbors a population reactive to TAP-impaired targets. The detection of such T-cell reactivity would indicate that, similar to mice, the human system contains a TEIPP-specific T-cell repertoire. To identify TEIPP antigens in humans, we set up a bioinformatics approach to predict HLA-I binding peptides with potential TEIPP characteristics in chapter 3. We made a start with a screening method to determine the immunogenicity of these self-peptides. An attractive strategy towards the development of immune-therapy based on TEIPPs is to identify TEIPPs in the human HLA-E molecule. This non-classical HLA-I molecule has only two variants among the human population. As these molecules only differ by one amino acid, the presented peptides are the same among humans. Moreover, HLA-E is frequently preserved or over-expressed in tumors. To gain a more profound insight in the peptide repertoire presented by the non-classical molecule HLA-E under conditions were TAP is impaired; we performed peptide elutions in chapter 4. Since these peptides derived from the elution are based natural selection through antigen presentation we also determine a peptide-binding motif for HLA-E. The implications of increased HLA-E expression in ovarian- and cervical carcinoma patients are assessed in chapter 5, in which we also study the presence of T-cells containing CD94/NKG2 receptors which are able to interact with HLA-E. It has been described in literature that the invariant chain interacts with HLA-I molecules, especially in the absence of TAP. This prompted us to test the idea that this protein-protein complex is implicated in the HLA-I presentation of TEIPPs. In chapter 6 we studied the surface expression of the CLIP peptide, which is derived from the invariant chain, in leukemia patients. We confirmed the interaction of the invariant chain with HLA-I molecules in leukemic cells, and surprisingly found that the CLIP peptide promiscuously binds HLA-I molecules, maybe as a result of this interaction. The existence and nature of human TEIPP antigens is reviewed in the discussion where we also give an overview on the current therapies aiming at counteracting MHC-I deficiencies in tumors Show less
T cells recognize pathogen-derived antigens and are crucial for fighting pathogens such as viruses and bacteria. In addition, T cells are able to recognize and attack certain types of tumors, in... Show moreT cells recognize pathogen-derived antigens and are crucial for fighting pathogens such as viruses and bacteria. In addition, T cells are able to recognize and attack certain types of tumors, in particular virally induced tumors. In this thesis we aimed 1) to obtain more insight into antigen-specific T cell responses and 2) to study how antigen-specific T cell responses can be improved. For the first aim we generated new tools that by enabling the visualization of antigen-specific CD4+ and CD8+ T cells allow the study of the dynamics of antigen-specific T cell responses in time throughout an ongoing immune response (chapter 2). In addition, we developed a novel technique that enables the study of family relationships between different T cell populations. This technique for instance allows us to determine whether two different types of effector T cell populations arise from the same or different pool(s) of na_ve T cells (chapter 5). For the second aim, we analyzed whether antigen-specific T cell responses can be manipulated by providing increased costimulation in the form of constitutive triggering of CD27 (chapter 3) or by generating CD4+ T cells that are modified by the introduction of MHC class I restricted TCRs (chapter 4). Show less
