Proteomic profiling differentiates classic Hodgkin lymphoma with and without skeletal involvement at the time of diagnosis

Introduction: Classic Hodgkin lymphoma (cHL) is a highly curable disease, even in advanced stages. It is controversial whether bone involvement has a negative effect on overall- and progression-free survival in patients treated with intensive chemotherapy. cHL is characterized by a unique tumor microenvironment (TME) consisting of few, scattered neoplastic Hodgkin and Reed-Sternberg (HRS) cells, embedded in an abundant background of reactive immune and stromal cells. When cHL disseminates, the new disease sites also contain both HRS cells and TME cells. Whether cases that present with bone lesions, harbour specific TME features is unknown. We investigated protein expression in lymph node biopsies from cHL patients with and without skeletal involvement at diagnosis, using nano liquid chromatography—tandem mass spectrometry (nLC-MS/MS), to identify potential markers of skeletal disease. Methods: Protein expression patterns in pre-therapeutic formalin-fixed, paraffin-embedded lymphoma samples from 69 cHL patients diagnosed at Aarhus University Hospital, Denmark between 2009 and 2018 were analysed by nLC-MS/MS. Patients were grouped according to diagnostic 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT). FDG PET/CT scans were reviewed specifically for bone involvement. The study cohort included 50 patients with nodal cHL (n-cHL) and no skeletal involvement, and 19 patients with both skeletal and nodal disease (s-cHL). Results: We identified 2,298 proteins; comparison of the protein profiles between the s-cHL and n-cHL groups revealed 220 unique proteins significantly differentially expressed (p < 0.05) and with a fold change of at least 25%. Of these, 117 proteins were upregulated (fold change 1.25–3.94), and 103 were downregulated (fold change 0.44–0.80) in s-cHL. In hierarchal clustering based on an even higher significance threshold (p < 0.001), i.e., 25 significantly differentially expressed proteins, two clusters were observed: (i) a skeletal-group comprising 12 s-cHL and 4 n-cHL samples; and (ii) a nodal-group of 46 n-cHL and 7 s-cHL samples. Of particular interest among the differentially expressed proteins, we identified isocitrate dehydrogenase (IDH1) and WD repeat- and FYVE domain-containing protein 4 (WDFY4). This pattern of protein expression suggests disturbance in cytoplasmic NADPH production, antigen processing/presentation, and B-cell survival in cHL patients with skeletal involvement compared to those without. Conclusion: Our data show differential protein expression in cHL lymphoma tissues that correlate with the presence or absence of concomitant bone involvement at diagnosis. This indicates that certain biological pathways are affected among those presenting with disease disseminated to the skeletal system. The research was funded by: Department of Clinical Medicine, Aarhus University; Health Research Foundation of Central Denmark Region; Brødrene Hartmanns Foundation; Carl and Ellen Hertz Foundation; the Danish Lymphoma Group; Kong Christian den Tiendes Foundation; Torben and Alice Frimodts Foundation; Aase and Ejnar Danielsens Foundation; Foundation of 1870; Dagmar Marshalls Foundation; Merchant Einar Willumsen’s Memorial Foundation; Eva and Henry Frænkel’s Memorial Foundation; Master Carpenter Jørgen Holm and wife Elisa f. Hansen’s Memorial Grant. The Orbitrap Fusion Tribrid mass spectrometer was funded by A. P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til Almene Formaal. Keywords: Genomics, Epigenomics, and Other -Omics, Hodgkin lymphoma, Microenvironment No conflicts of interests pertinent to the abstract.