The post-translational modification of histones and their interaction with transcription factors is essential to gene regulation. Furthermore, these targets would greatly benefit from probe molecules to fully elucidate their biological actions and to potentially lead to therapeutics. However, these protein-protein interactions have been considered difficult to inhibit and few high-quality chemical probes currently exist for the study of epigenetic biological systems in particular.

Case Report: Diffuse Large B Cell Lymphoma (DLBCL) is an aggressive tumor of B cells that can arise almost anywhere in the body. It is the most common type of non-Hodgkin lymphoma in adults. We report a case of double hit lymphoma, a rare subtype that has an abnormal MYC and BCL2 gene translocation and occurs in about 5% of DLBCLs. A 58-year-old male with a 15-year smoking history presented with abdominal pain accompanied by weight loss of 20 lbs, night sweats, poor appetite, and fatigue. CT angiogram showed posterior mediastinal mass 3.5x5.6x12.8 cm, massive lymphadenopathy in the retroperitoneum surrounding aorta 10.5x5.2x11cm and a large left upper quadrant mesenteric mass measuring 7.2x10.2x13.6 cm. Left abdominal mass was biopsied and pathology showed DLBCL. FISH showed double hit lymphoma. Bone marrow biopsy and aspiration was negative for involvement. LV EF was 61% per ECHO. Patient underwent PET/CT, which showed extensive adenopathy in the inferior neck, chest, and abdomen, as well as a retroperitoneal mass extending into T10-11 extradural space. International Prognostic Index (IPI) for DLBCL categorized the patient as having a poor prognosis and in the high-intermediate risk group with a 4 year overall survival of 55% and 4 year progression-free survival of 53%. The PET scan results showing multiple extranodal sites was a factor in calculating his prognosis. MRI T spine with contrast showed direct invasion of T9, 10, 11, and 12. Urgent chemotherapy was started with DA-R-EPOCH. Our case demonstrates how imaging predicts the aggressiveness of DLBCL biology. The PET scan is very important in determining the extent of disease and the stage to allow for risk stratification of patients with DLBCL.

Introduction: Diffuse large B-cell lymphoma, not otherwise specified (DLBCL NOS) is subdivided according to the cell-of-origin (COO) classification into germinal centre B-cell (GCB) and activated B-cell (ABC) subtypes, each with different molecular profiles and clinical behaviour. This study aims to describe the pattern of the COO subtypes, the proportion of Epstein-Barr virus (EBV) co-infection, and their influence on survival outcomes in a setting of high HIV prevalence. Materials and Methods: This retrospective cohort study included patients diagnosed with de novo DLBCL NOS at our tertiary academic centre in Cape Town, South Africa over a 14-year period. Immunohistochemical stains were performed for COO classification, according to the Hans algorithm. Tumour EBV co-infection was established by EBV-encoded ribonucleic acid in situ hybridisation (EBER-ISH) staining. The effect of the COO subtypes and EBV co-infection on overall survival were described by means of univariate, bivariate and multivariate analyses. Results: A total of 181 patients with DLBCL NOS were included, which comprised 131 HIV-uninfected and 50 HIV-infected patients. There was an equal distribution of GCB and ABC subtypes in the HIV-infected and HIV-uninfected groups. EBV co-infection was detected in 16% of the HIV-infected cases and in 7% of the HIV-uninfected cases (p=0.09). There was no significant difference in the incidence of EBV co-infection between the GCB and ABC subtypes (p=0.67). HIV-infected patients with CD4≥150 cells/mm3 had similar survival to HIV-uninfected patients (p=0.005). Multivariate regression analysis showed that in the HIVinfected group with marked immunosuppression (CD4 <150 cells/mm3), there was significantly poorer overall survival compared to the HIV-uninfected group (HR 2.4, 95% CI 1.3–4.1). There were no statistically significant differences in overall survival by DLBCL COO subtype. Conclusions: There was no difference in the proportion of DLBCL COO subtypes, regardless of HIV status. EBV co-infection was more common in the HIV-infected group, but less than described in the literature. Unexpectedly, there were no significant differences in survival outcomes between the GCB and ABC subtypes. Higher CD4 counts in the HIV-infected group had good survival outcomes, while lower CD4 counts predicted adverse survival outcomes. Further research is needed to explore the genetic mutational landscape of HIVassociated DLBCL.

Die heterogene Biologie der diffusen großzelligen B-Zell-Lymphome (DLBCL) und die daraus resultierenden Unterschiede in Therapieansprechen und Prognose stellen ein wesentliches Problem in der aktuellen Therapie von DLBCL dar. Anomalien im kanonischen Wnt-Signalweg und seinen natürlichen Antagonisten wie secreted frizzled-related proteins (SFRPs) sind für verschiedene solide und hämatologische Malignome als wichtige Bestandteile der Tumorgenese und Tumorprogression identifiziert worden. Vorarbeiten unserer Arbeitsgruppe lieferten Hinweise für die Bedeutung von Wnt3a und SFRP4 in der Regulation von DLBCL. Im Rahmen dieser Arbeit wurde untersucht, welche Rolle dem Protein SFRP4 in der Wachstumsregulation von diffusen großzelligen B-Zell-Lymphomen zukommt. Die Synthese von SFRP4 wurde in den als Modellzelllinien genutzten humanen DLBCL-Zelllinien nachgewiesen. Unter Verwendung von rekombinantem humanen SFRP4 sowie einer mittels lentiviraler shRNA erzeugten Expressionsreduktion von SFRP4 konnte gezeigt werden, dass SFRP4 zu einer Expansionshemmung sowie zu einer reduzierten Klonogenität bei DLBCL-Zellen führt. Als Ursache für diese Effekte konnte die Inhibition des kanonischen Wnt-Signalwegs durch SFRP4 identifiziert werden. SFRP4 wurde hinsichtlich seiner Bedeutung für die Ausprägung der Side Population (SP), einer Tumorzellsubpopulation mit repopulativem Potenzial, in DLBCL-Zellen untersucht. Dabei wurde sowohl durch exogene Zugabe als auch durch Reduktion von SFRP4 auf Transkriptebene die Bedeutsamkeit von SFRP4 für die SP-Regulation gezeigt. Untersuchungen zur differentiellen SFRP4-Expression sowie SFRP4-Promotormethylierung in Side Population versus non-Side Population wiesen epigenetische Mechanismen in der Regulation des SP-Phänotyps nach. Das DNA-demethylierende Medikament 5-Azacytidine reduzierte in DLBCL-Zelllinien Expansion sowie Klonogenität. Darüber hinaus beeinflusste 5-Azacytidine den kanonischen Wnt-Signalweg und den SFRP4-Gehalt der DLBCL-Zellen. Die Bedeutung von Exosomen als interzelluläre Kommunikatoren, die Wnt-Proteine transportieren, wurde unter besonderer Berücksichtigung von SFRP4 evaluiert. Sowohl SFRP4 als auch Wnt3a waren in der Exosomen- und der Mikrovesikelfraktion von DLBCL-Zellen nachweisbar. Die Exosomen waren in der Lage, den kanonischen Wnt-Signalweg an den Zielzellen zu aktivieren und Einfluss auf die Side Population zu nehmen. Insgesamt wurde für SFRP4 erstmalig eine hemmende Wirkung auf das Wachstum von DLBCL-Zellen demonstriert. Weiterführende Studien können adressieren, inwiefern die aufgezeigten Mechanismen der Wachstumsmodulation von DLBCL-Zellen durch SFRP4 in therapeutischen Anwendungen genutzt werden können.

Zelluläre Seneszenz beschreibt einen terminalen Zellzyklus-Arrest. Nach zellulärem Stress u. a. durch aktivierte Onkogene oder DNA-schädigende Chemotherapie wird Seneszenz induziert und kann so zur Tumorsuppression bzw. zum Behandlungserfolg beitragen. Vor kurzem wurde gezeigt, dass der Transkriptionsfaktor NF-kappaB – welcher bisher vor allem durch seine onkogenen Funktionen mit Krebs in Verbindung gebracht wurde - bei der Seneszenz-assoziierten Zytokinausschüttung mitwirkt und den seneszenzten Phänotyp möglicherweise sogar verstärkt, wodurch NF-kappaB potentiell eine tumorsuppressive Rolle zukäme. Ziel dieser Arbeit ist die Untersuchung des NF-kappaB-Signalweges in Seneszenz und Therapie. In der vorliegenden Arbeit zeige ich die deutliche Aktivierung von NF-kappaB nach Therapie-induzierter Seneszenz (therapy-induced senescence, TIS) und erhöhte Expression NF-kappaB-regulierter Zytokine. TIS ist vor allem in vivo mit starker Aktivität des NF-kappaB-Signalweges assoziiert und von selbiger abhängig. Primäre Eµ-myc-transgene Mauslymphome wurden nach ihrer endogenen NF-kappaB-Aktivität klassifiziert bzw. mit inhibierenden und aktivierenden NF-kappaB-Konstrukten modifiziert, welche auch in diffusen großzelligen B-Zell Lymphomen (diffuse large B-cell lymphoma, DLBCL) als natürlich vorkommende Mutationen gefunden wurden. Über einen neuartigen „Cross-Species“-Vergleich wurden Bcl2-hochexprimierende Keimzentrums-B-Zell-DLBCL (germinal center B-cell type, GCB) als klinisch relevante Gruppe identifiziert, welche nach NF-kappaB-Hyperaktivierung signifikant besser auf Therapie ansprach. Diese Ergebnisse zeigen eine kontextspezifische, d. h. von „onkogenen Netzwerken“ abhängige Rolle des NF-kappaB Signalweges unter Chemotherapie. Diese Information könnte für künftige klinische Studien bedeutsam sein, da sie Bedingungen aufzeigt, unter denen NF-kappaB als Vermittler einer erwünschten Therapie-induzierten Seneszenzantwort eher nicht inhibiert werden sollte. / Cellular senescence is a terminal cell-cycle arrest program that is executed in response to cellular stresses, such as activated oncogenes or DNA-damaging anti-cancer chemotherapy, where it serves as a tumor-suppressive mechanism or contributes to treatment outcome, respectively. Recently, transcription factor NF-kappaB which has long been linked to cancer development primarily through its oncogenic functions, has been postulated to participate in a senescence-associated and possibly senescence-reinforcing cytokine response, thereby suggesting a tumor-restraining role for NF-kappaB. The aim of my PhD project was to understand the role of the NF-kappaB pathway in senescence and cancer treatment outcome. In this thesis, I show markedly elevated NF-kappaB activity upon therapy-induced senescence (TIS), associated with strong upregulation of NF-kappaB-controlled cytokines. TIS is associated with and depends on hyper-activated NF-kappaB signaling. By characterization and genetic engineering of primary mouse lymphomas according to distinct NF-kappaB-related oncogenic networks reminiscent of diffuse large B-cell lymphoma (DLBCL) subtypes, Bcl2-overexpressing germinal center B-cell-like (GCB) DLBCL were identified as a clinically relevant subgroup with significantly superior outcome when NF-kappaB is hyperactive. These results demonstrate the context-dependent role of NF-kappaB signaling in cancer therapy and unveil oncogenic scenarios in which NF-kappaB hyperactivity unexpectedly accounts for superior long-term outcome to therapy. This finding has significant ramifications for future clinical trials that aim at inhibiting NF-kappaB activity based on the assumption of its detrimental impact on treatment outcome.

No description available.

1 ABSTRACT B-cell non-Hodgkin lymphomas (B-NHL) represent the most common mature lymphoproliferative diseases. B-NHL arise at different stages of B-cell development and represent their malignant counterpart. Diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) are aggressive types of B-NHLs. Deregulation of cell cycle control, inhibition of apoptosis or abnormal DNA damage response play a key role in the pathogenesis of DLBCL and MCL. Aberrant activation of several signaling pathways that further promote survival, cell proliferation or affect the tumor microenvironment have been recently recognized. Increased understanding of the oncogenic mechanisms implicated in pathogenesis of B-NHL lead to development of novel agents that target the oncogenic drivers of distinct lymphoma subtypes. MCL is an aggressive subtype of B-NHL associated with poor prognosis. In vivo models of human MCL for experimental therapy are however scarce. We established and characterized several mouse models of human MCL by xenotransplantation of either primary cells or established cell lines into immunodeficient mice (publication no 1). We demonstrated that engrafted MCL cells displayed complex changes of gene expression profile, phenotype and sensitivity to cytotoxic agents compared to the original in vitro growing...

The PIM family kinases promote growth and survival of tumor cells and are expressed in a wide variety of human cancers. Their potential as therapeutic targets, however, is complicated by overlapping activities with multiple other pathways and remains poorly defined in most clinical scenarios. Here we explore activity of the new pan-PIM inhibitor PIM447 in a variety of lymphoid-derived tumors. We find strong activity in cell lines derived from the activated B-cell subtype of diffuse large B-cell lymphoma (ABC-DLBCL). Sensitive lines show lost activation of the mTORC1 signaling complex and subsequent lost activation of cap-dependent protein translation. In addition, we characterize recurrent PIM1 protein-coding mutations found in DLBCL clinical samples and find most preserve the wild-type protein's ability to protect cells from apoptosis but do not bypass activity of PIM447. Pan-PIM inhibition therefore may have an important role to play in the therapy of selected ABC-DLBCL cases.

No description available.

Primary gastrointestinal lymphoma is the most common type of extra-nodal lymphoma, representing about 30-50% of all extra-nodal involvement. The stomach is the most common site, with the colon and rectum accounting for a minority of occurrences. Primary colorectal lymphoma is uncommon, representing only 0.3% of all large intestinal malignancies and approximately 3% of GI lymphomas with the majority of these being B-cell non-Hodgkin lymphoma and diffuse large B-cell lymphoma (DLBCL) being the most common subtype. We present a case of an 85-year-old male who presented with symptoms suggestive of bowel obstruction, who after further evaluation was diagnosed with primary non-Hodgkin lymphoma of the colon, DLBCL subtype.