<p>Difuzni krupnoćelijski B limfom je najče&scaron;ći limfom na svetu i obuhvata do 30% non Hodgkin limfoma u zapadnim zemljama i veći procenat u zemljama u razvoju i nerazvijenim zemljama. Obično nastaje de novo ali može nastati sekundarno kao rezultat progresije manje agresivnih limfoma. U većini slučajeva počinje u limfnim čvorovima. Histolo&scaron;ka slika nije uniformna kod svih podtipova DLBCL, zbog morfolo&scaron;kog diverziteta tumorskih ćelija i zbog pratećih neneoplastičnih procesa. Na&scaron;e istraživanje obuhvata 92 bolesnika koji su dijagnostikovani i lečeni na Institutu za onkologiju Vojvodine od 2003. do 2011. godine, od kojih je 66 imalo kompletna imunohistohemijska ispitivanja. Svi su lečeni standardnim protokolom koji uključuje rituksimab. Ispitivali smo morfolo&scaron;ki i imunohistohemijski podtip, ekspresiju imunohistohemijskih markera, pol, starost, stadijum, nodalno/ekstranodalno ishodi&scaron;te i preživljavanje. CD20 je bio pozitivan u svim dostupnim uzorcima. MUM1 u 62,07%, CD10 u 20,23%, BCL6 u 51,72%, CD30 u 10,81%, CD5 u 8,05%, Ki-67 u 30-92%, BCL2 u 39,33%, BAFFR u 46,15%, TACI u 43,94%, BCMA u 10,61%, VEGF u 27,7%, COX2 u 63,64%, CD43 u 18,52%, EBV LMP u 37,88%. Među obolelim ženama je statistički značajno veći procenat MUM1 pozitivnih i BAFFR pozitivnih bolesnika nego među obolelim mu&scaron;karcima. Kod starijih ispitanika je statistički signifikantno ređa ekspresija CD30, COX2, TACI i BCMA. Kod ekstranodalnih limfoma ekspresija TACI je če&scaron;ća nego kod nodalnih limfoma. Ispitanici sa pozitivnom ekspresijom COX2 i ispitanici sa pozitivnom ekspresijom TACI imaju značajno izraženiju ekspresiju Ki-67. Bolesnici sa negativnom ekspresijom BCL2 imaju statistički značajnu korelaciju sa negativnom ekspresijom CD5 i negativnom ekspresijom CD43. Bolesnici sa pozitivnom ekspresijom CD30 imaju statistički značajnu pozitivnu korelaciju sa ekspresijom BCMA. Ispitanici sa pozitivnom ekspresijom COX2 imaju statistički značajnu pozitivnu korelaciju sa ekpresijom TACI. Markeri aktivacije i diferencijacije limfocita nemaju statistički značajnu pozitivnu korelaciju sa boljom prognozom. Markeri signalnih puteva angiogeneze i inflamacije nemaju statistički značajnu pozitivnu korelaciju sa lo&scaron;ijom prognozom. Izgleda da treba biti racionalan i upotrebiti samo osnovna antitela za određivanje imunohistohemijskog podtipa i antitela potrebna za diferencijalnu dijagnozu. Čini se da je prognostički značaj imunohistohemijskih antitela (osim CD20) danas kada se u terapiji koristi Rituximab minimalan.</p> / <p>Diffuse large B-cell lymphoma is the most common lymphoma in the world and represents up to 30% of all NHL in western countries and more in developing and undeveloped countries. It is usually a primary disease but also it can develop secondary as a result of progression of low grade lymphomas. In most cases the disease begins in lymph nodes. Histological features are not uniform in all subtypes of DLBCL due to morphological diversity and following non-neoplastic processes. Our research includes 92 patients whom are diagnosed and treated at the Institute for Oncology of Vojvodina since 2003. to 2011. and 66 among them have complete immunohistochemical findings. All of them are treated with standard protocols including Rituximab. We have examined morphological and immunohistochemical subtype, expression of immunohistochemical markers, sex, age, stadium, nodal / extranodal origin and survival. CD20 was positive in all available samples. MUM1 in 62,07%, CD10 in 20,23%, BCL6 in 51,72%, CD30 in 10,81%, CD5 in 8,05%, Ki-67 in 30-92%, BCL2 in 39,33%, BAFFR in 46,15%, TACI in 43,94%, BCMA in 10,61%, VEGF in 27,7%, COX2 in 63,64%, CD43 in 18,52%, EBV LMP in 37,88%. Female patients have significantly more often MUM1 and BAFFR expression compared to male patients. Older patients have significantly less often CD30, COX2, TACI and BCMA expression. Extranodal lymphomas have more frequent TACI expression then nodal ones. Patients with COX2 expression and patients with TACI expression have significantly higher Ki-67 expression. Patients without BCL2 expression have a significant correlation with CD5 negative expression and CD43 negative expression. Patients with CD30 expression have significant correlation with BCMA expression. Patients with COX2 expression have significant correlation with TACI expression. Markers of activation and differentiation of lymphocytes do not have significant correlation with better prognosis. Markers of signaling pathways for angiogenesis and inflammation do not have a significant correlation with worst prognosis. It seems that we should be rational and use only basic antibodies for determination if immunohistochemical subtype and antibodies necessary for differential diagnosis. It seems that prognostic significance of immunohistochemical antibodies (except CD20) is minimal today in Rituximab era.</p>

INTRODUCTION: Chimeric antigen receptor (CAR) T-cell therapy is a new treatment for hematologic malignancies including aggressive B-cell non-Hodgkin’s lymphoma (NHL). Although it has provided an effective treatment option for patients who have few options, CAR T-cell therapy does have many associated toxicities. Prolonged cytopenias are one of the lesser understood toxicities that can affect upwards of 40% of patients. METHODS: In this retrospective study, we reviewed 106 patients who received commercial CAR T-cell therapy between November 2017 and September 2019. Prolonged cytopenias were defined as having absolute neutrophil count (ANC) <1000/mm3, platelets (PLT) <50,000/mm3, and/or hemoglobin (Hgb) <10 g/dL at least once after 30 days post-CAR T-cell infusion. Furthermore, if only one incidence of cytopenia was recorded 30 days post infusion, we required that the patient had to have received either a transfusion or granulocyte-colony stimulating factor (GCSF) after the date of the recorded cytopenic value to be considered a part of the cytopenic cohort. RESULTS: 22 patients met the criteria of having prolonged cytopenias. 64% of the cytopenic cohort had >1 type of prolonged cytopenias. Anemia was the most prevalent affecting 72% of cytopenic patients. The length of time from diagnosis of aggressive B-cell NHL to date of CAR T-cell infusion was found to be positively correlated with an increased risk of developing prolonged cytopenias following CAR T-cell therapy. Additional risk factors associated with an increased risk of delayed cytopenias by univariate analysis included neutropenia on the day of infusion (day 0), a high C-reactive protein (CRP) before lymphodepletion and on day 0, day 0 PLT count, and Hgb before lymphodepletion and on day 0. On multivariate analysis, only high CRP before lymphodepletion was associated with an increased risk of prolonged cytopenias while high ferritin and PLT values on day 0 were associated with not developing prolonged cytopenias. There was no statistical difference between the cytopenic and non-cytopenic cohorts in rates of progression free survival (PFS) and overall survival (OS). Also, no difference was seen in rates or severity of other toxicities between cohorts. 41% of the cytopenic cohort experienced infectious complications post-infusion with one patient dying from their infectious complications. However, there was no association with incidence of infection and prolonged cytopenias when compared to the incidence of infection in the non-cytopenic cohort. CONCLUSIONS: A longer time from diagnosis of aggressive B-cell NHL to time of CAR T-cell infusion was associated with prolonged cytopenias while the number of lines of prior chemotherapy and rate of prior high dose chemotherapy with an autologous stem cell transplant (HD-ASCT) were not associated. It would be valuable to confirm this association and why it is associated since the other two factors were not. We lacked bone marrow biopsies before CAR T-cell infusion and did not have bone marrow biopsies for many patients after CAR T-cell infusion. It would be beneficial to collect data regarding bone marrow biopsies from these time points to highlight any changes that could be related to CAR T-cell therapy. Cytogenetic information of individual patient’s diseases would be worth analyzing to help determine if there are biological factors associated with prolonged cytopenias in response to CAR T-cell therapy. Additional studies should investigate the laboratory values we found to have associations with either cohort to help identify possible predictive values providers could use to identify patients at higher risk of having prolonged cytopenias. There is also a need to see if specific prior chemotherapy regimens increase a patient’s risk of having prolonged cytopenias. Overall, since prolonged cytopenias after CAR T-cell infusions have not been heavily investigated, further investigation is needed to better understand the predictive factors and identify possible mechanisms of prolonged cytopenias seen in CAR T-cell patients.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22727号 / 医博第4645号 / 新制||医||1045(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 濵﨑 洋子, 教授 羽賀 博典, 教授 伊藤 貴浩 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Kaposi's sarcoma herpesvirus (KSHV) is a cancer-causing virus, primarily affecting AIDS patients. KSHV is found in 3-10% of the U.S. population and can cause a range of cancers in the highly immunosuppressed; these cancers include Kaposi's sarcoma, pleural effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). The current techniques for treating these cancers are relatively ineffective, largely due to their inefficiency at targeting tumors formed by the infection. One protein produced by KSHV, the viral homolog of interleukin-6 (vIL-6), is thought to play a major role in tumor development post-infection. Here a novel animal model is implemented to study the ways vIL-6 affects tumor development through growth factors and other cytokines within infected highly immune-deficient Rag2-/-γc-/- mice. Mice were subcutaneously injected with one of three types of cells: B cells infected with a wild-type (WT) KSHV, B cells infected with mutant KSHV without the gene for viral interleukin 6, and a negative control of uninfected B cells. After allowing time for tumors to develop the mice were sacrificed and the tumors assessed. Analysis of the physical properties of the tumors, as well as markers expressed by the tumors, were used to help determine whether vIL-6 could be an appropriate target when treating these cancers. In this study vIL-6 was seen to influence certain B cell markers (CD30), as well as onset of tumors (with no significant increase in overall tumor mass, but with marginally statistically significant increase in tumor number). This indicates that although vIL-6 could play a small role as a target for cancer, further investigation into the relationship of CD30 in these types of cancers needs to be explored. It was also found that the KSHV viral-infection decreases the development of tumors compared with uninfected immortalized B cells (BJAB). Not only would results from this experiment help develop new treatments, and change the lives of those suffering with cancers induced by KSHV, but they would provide a foundation for future studies with these types of cancers.

Le cancer est un problème majeur de santé public, tuant chaque année plusieurs millions de personnes. L’inhibition de la mort cellulaire programmée, l’apoptose, est considérée comme l’un des paramètres principaux impliqués dans son initiation et son développement. La régulation de la voie intrinsèque (mitochondriale) de l’apoptose est régulée par la famille Bcl-2. Jusqu’à maintenant, on pensait que la protéine PUMA, une protéine pro-apoptotique, était principalement exprimée au niveau mitochondrial. Nous avons montré qu’à l’état basal, PUMA était exprimé au niveau du cytosol des lymphocytes B humains. Cependant, suite à un signal apoptotique, PUMA est capable de transloquer du cytosol à la mitochondrie, de façon indépendante des caspases mais dépendante de l’activation de la MAPKinase p38, permettant ainsi son interaction avec les protéines anti-apoptotiques Bcl-2 et Mcl-1 dont l’inhibition conduit à l’apoptose. Les protéines anti-apoptotiques, Mcl-1 notamment, sont souvent surexprimées dans les tumeurs. Mcl-1 est une protéine à courte demi-vie, rapidement dégradée par le protéasome. Cette dégradation dépend de son ubiquitination réalisée par des E3 ligases (E3). Quelques E3 et une déubiquitinase (DUB), hydrolysant les chaînes d’ubiquitine, régulant l’expression de Mcl-1 ont été décrites. Cependant, ces protéines sont soit très peu exprimées, soit leur inhibition n’a pas d’impact sur l’expression de Mcl-1 dans notre modèle. Nous avons donc entrepris de caractériser de nouvelles E3 et DUB régulant l’ubiquitination de Mcl-1. Après une immunoprécipitation de Mcl-1 dans nos cellules, suivie d’une analyse par spectrométrie de masse, nous avons identifié la DUB USP14. Lorsque son expression est diminuée, l’expression et la stabilité de Mcl-1 augmentent de façon sélective. Nos résultats pourraient contribuer à une approche à double-tranchant dans le traitement du cancer, en retirant les freins à l’apoptose via une diminution de l’expression de Mcl-1 d’une part et en l’activant via PUMA de l’autre. / Cancer is a major public health issue, killing millions of people worldwide each year. The inhibition of apoptosis, a programmed cell death, in its onset and development has been well documented, making it one of the hallmarks of cancer. The regulation of the intrinsic (mitochondrial) pathway of apoptosis is regulated by the Bcl-2 (B cell lymphoma-2) family. Up until now, PUMA, a pro-apoptotic protein, was thought to be mainly expressed at the mitochondria, based on experiments where it had been overexpressed. We showed that endogenous PUMA is mainly expressed in the cytosol of activated or resting B cells. However, upon apoptotic stress, PUMA was able to translocate from the cytosol to the mitochondria, in a caspase-independent but p38-dependent manner, allowing PUMA to bind and inhibit the anti-apoptotic proteins Bcl-2 and Mcl-1, and thereby leading to cell death. The anti-apoptotic proteins, especially Mcl-1, are often overexpressed in tumors. Mcl-1 is a protein with a short half-life, degraded rapidly by the proteasome. This degradation is ubiquitin-dependent, requiring E3 ligases (E3). A handful of E3s and one deubiquitinase (DUB), that hydrolyses the ubiquitin chains, have been reported to regulate Mcl-1 expression. However, they were either very poorly expressed or their inhibition had no impact on Mcl-1 expression in our model. We thus undertook to characterize new E3s and DUBs mediating Mcl-1 ubiquitination. After an immunoprecipitation of Mcl-1 in our cells, followed by a mass spectrometry analysis, we identified the DUB USP14. When knockdown, Mcl-1 expression was selectively increased and its stability enhanced. Our results could help build “double-edge” therapies, removing the breaks on apoptosis on one hand via Mcl-1 downregulation while activating it on the other via PUMA translocation.

Les leucémies/lymphomes à cellules T de l’adulte (Adult T-cell leukemia/Lymphoma, ATL) sont des hémopathies lymphoïdes T CD4+ malignes matures rares, induite par le rétrovirus HTLV-1 (Human T lymphotropic virus type 1). Nous avons étudié différents aspects moléculaires de la lymphomagenèse HTLV-1 induite sur une série rétrospective de patients pris en charge pour un ATL.Nous avons dans un premier temps étudié la marque épigénétique hydroxymethylation (5hmc) de l’ADN, ainsi que les enzymes la régulant sur des cellules primaires d’ATL. Nous avons observé une diminution du taux de 5hmc dans les formes agressives comparativement aux formes indolentes qui corrélait avec une diminution de l’expression de la dioxygénase TET2 et avec la survie des malades. Nous avons également mis en évidence la présence de mutations somatiques du gène TET2 chez moins de 10% des patients et identifié un polymorphisme surreprésenté dans le locus de TET2 chez les patients atteints ATL comparé à des patients chroniquement infectés sains ethniquement appariés.Dans un deuxième temps, nous avons exploité une technique de PCR « ligation médiée » suivie d’un séquençage à haut débit afin d’étudier l’architecture de l’intégration virale comme outil de maladie résiduelle. Nous avons retrouvé une meilleure sensibilité de cette technique pour définir la réponse au traitement par rapport aux critères de réponse actuels ouvrant la voie de son utilisation pour le suivi des patients.Enfin, nous avons étudié le paysage des altérations génomiques sur une cohorte de 60 patients par une approche globale. Nous avons observé des mutations sur 3 voies principales : TCR/NF-KB, trafic cellulaire T et échappement au système immunitaire corroborant les résultats d’une récente étude sur une population de patients japonais. L’analyse par RNAseq a révélé la perturbation systématique de l’expression génique cellulaire induite par l’intégration virale soit par le biais d’un transcrit chimérique partant du LTR 3’ viral soit par un arrêt de la transcription d’un gène cellulaireLe suivi de patients progressant d’une forme indolente à une forme agressive a révélé l’acquisition de mutations activatrices principalement sur la voie de signalisation TCR/NF-KB. Le suivi de patients ayant rechuté après une période de rémission a également révélé l’acquisition de nouvelles mutations.Ces résultats soulignent la spécificité de la lymphomagenèse HTLV-1, qui procède d’une part d’évènements secondaires à l’intégration virale au sein du génome cellulaire, induisant la perturbation de l’expression de gènes cellulaires (premier évènement oncogénique) et d’autre part à l’accumulation d’altérations génomiques secondaires, communs aux autres hémopathies lymphoïdes T et B matures, responsables de la transformation. / Adult T cell leukemia/lymphoma (ATL) is a rare and mature T cell malignancy induced by the retrovirus HTLV-1 (Human T-lymphotropic virus type 1) which bears a dismal prognosis. We have studied several molecular aspects of HTLV-1 induced lymphomagenesis on a retrospective cohort of ATL patients.First, we analyzed the global level of the DNA epigenetic mark hydroxymethylation (5hmc) as well as of enzymes implicated in its regulation in primary ATL cells. We observed a reduction of the 5hmc level in aggressive ATL compared to indolent forms with a positive correlation between the reduction of the 5hmc level, the decrease of the TET2 dioxygenase transcript and the patient overall survival. We found that somatic mutations in TET2 were present with a frequency of less than 10% but identified a SNP in TET2 locus whose frequency in ATL patients was higher compared to that of an ethnically matched control population.In a second part, we took advantage of a new technique of ligated mediated PCR followed with high throughput sequencing to analyze the viral integration architecture as a means of minimal residual disease detection. We demonstrate that this technique allows a better definition of the treatment response compared to actual consensus response criteria.Finally, we performed an integrated genomic analysis of a retrospective cohort of 60 ATL patients. We identified alterations targeting the TCR/NFKB signaling pathway, T cell trafficking and immune escape mechanisms, consistent with previous findings described in a Japanese ATL cohort. RNAseq analysis revealed the systematic perturbation of host gene expression secondary to viral integration and proceeding via the viral antisense leading to the production of a virus-host chimeric transcript production or the direct transcription termination of a host gene. Analysis of matched sequential samples of patients progressing from an indolent to an aggressive form revealed in most of the cases the acquisition of mutations affecting the TCR/NF-KB pathway. Analysis of sequential samples from patients who relapsed after a remission period also showed the acquisition of additional genetic alterations.These results underscore the specific nature of HTLV-1 induced lymphomagenesis, which proceeds on the one hand through mechanisms induced by the viral integration in the host genome, and consequent host-gene expression perturbation (viral first oncogenic hit) and on the other hand through secondary oncogenic mutations in various pathways, common to other mature B and T cell lymphoid malignancies.

Les lymphomes cutanés primitifs B comprennent 2 formes indolentes (lymphomes des centres folliculaires et de la zone marginale) et une forme clinique agressive, le lymphome B diffus à grandes cellules de type jambe. Si le lymphome des centres folliculaires ne présente le plus souvent pas la translocation t(14;18) à l'origine d'une dérégulation de BCL2 caractéristique des lymphomes folliculaires ganglionnaires, elle peut être identifiée en FISH dans 8,7% des cas et représenter un risque d'extension extra-cutanée. En revanche, l'étude de l'oncogenèse des lymphomes B de type jambe révèle des mécanismes communs d'oncogenèse avec les lymphomes B diffus à grandes cellules ganglionnaires, avec une répartition différente des altérations. Notamment, la mutation du gène MYD88L265P qui encode une protéine adaptatrice de la voie des Toll-like récepteurs responsable de l'activation constitutive de la voie NFκB, est très fréquemment observée (69% des cas) et est associée à une survie spécifique plus courte. De plus, contrairement aux autres lymphomes cutanés B, les cellules tumorales sont porteuses de multiples anomalies comme des translocations ou des délétions. D'autres arguments issus de l'analyse des séquences des gènes des immunoglobulines nous permettent de présumer que la cellule d'origine est un lymphocyte B mature, post-centre germinatif. Le fort taux de mutations identifiées reflète l'hypermutation somatique acquise à l'occasion du passage par le centre germinatif, mais l'expression d'un isotype primaire d'anticorps (IgM) suggère un blocage de la différentiation plasmocytaire terminale notamment pour la commutation isotypique. / Cutaneous B-cell lymphomas are represented by indolent B-cell lymphomas (follicle center and marginal zone), and primary cutaneous diffuse large B-cell lymphoma, leg-type which is characterized by an aggressive behavior. Primary cutaneous follicle center lymphoma usually do not harbor the t(14;18) translocation, which is characteristic of nodal follicular lymphoma and conduct to BCL2 overexpression. However, it can be observed by FISH in 8.7% of cutaneous cases and seems to be associated with extra-cutaneous disease. In contrast, primary cutaneous diffuse large B-cell lymphoma, leg-type shows common genetic alterations with its nodal counterpart diffuse large B-cell lymphoma, suggestive of common oncogenesis pathways, with distinct frequencies and repartition ofmutations. Especially, the MYD88L265P mutation that encodes an important adaptator protein of the Toll-like receptor pathway, activating NFκB, is very frequent (69% of cases) and associated with a shorter specific survival. Moreover, contrary to indolent primary cutaneous B-cell lymphoma, tumour cells often harbor multiple genetic alterations such as translocations and deletions. The analysis of the immunoglobulin genes sequences led us to suppose that the cell of origin could be a post germinal-center mature B-cell. Highly mutated sequences are the reflection of the germinal center passage, but IgM expression suggests a terminal differentiation blockage, notably with a class switch recombination defect.

Le lymphome diffus à grandes cellules B (DLBCL, Diffuse Large B-Cell Lymphoma) constitue le lymphome non Hodgkinien le plus fréquemment diagnostiqué. Les DLBCL sont composés principalement de deux sous groupes : l’entité nommée ABC (Activated B Cell-like) qui est la plus agressive, avec un taux de survie de 30% après traitement, et l’entité GCB (Germinal-Center B Cell). Contrairement aux GCB DLBCL, les ABC DLBCL se caractérisent par une signature génique similaire aux lymphocytes B activés par leur récepteur antigénique (BCR, B Cell Receptor) à cause de l'accumulation de mutations génétiques. Ceci a pour conséquence une activation constitutive du facteur de transcription NF-κB pour laquelle les lymphomes ABC DLBCL ont développé une profonde addiction. Toutefois, la nature pléiotrope de NF-κB rend son ciblage thérapeutique inenvisageable. Mon projet de thèse visait à caractériser de nouveaux régulateurs de la voie d’activation du facteur NF-κB par les récepteurs antigéniques en condition physiologique et pathologique. Dans un premier temps, grâce à un crible protéomique par spectrométrie de masse, nous avons identifié un complexe ternaire nommé LUBAC (Linear Ubiquitin Chain Assembly Complex) comme un acteur majeur de l’activation de NF-κB par le TCR et le BCR, et de la survie des lymphomes ABC DLBCL. Dans un second temps, le crible d’une librairie de mille deux cents molécules chimiques nous a permis d’isoler un composé sélectivement toxique in vitro pour les lymphomes ABC DLBCL. Nous montrons que ce composé entraine la mort apoptotique des ABC DLBCL sans toutefois affecter la signalisation NF-κB. Un tel composé pourrait, dans le futur, être utilisé comme une nouvelle molécule thérapeutique pour le traitement du lymphome ABC DLBCL. / The diffuse large B cell lymphoma (DLBCL) is the most common non Hodgkinien lymphoma. Two main different entities composed the DLBCL : the Activated B Cell-like subtype (ABC DLBCL) witch is the most aggressive and associated with a poor survival prognostic, and the Germinal-Center B Cell subtype (GCB DLBCL). Unlike the GCB DLBCL, ABC DLBCL are characterized by a genetic signature similar to activated B lymphocytes stimulated by their antigen receptor (BCR, B cell receptor) which results from mutations accumulation. As a consequence, ABC DLBCL survival and proliferation requires the constitutive activation of NF-κB transcription factors. Because NF-κB has pleiotropic effect on different tissues, strategies aiming at targeting NF-κB heterodimers might have deleterious consequences on an organism.My project focuses on identifying new modulators involved in antigen receptor mediated NF-κB activation in physiological and pathological condition.We first performed a mass spectrometry analysis and identified the LUBAC (Linear Ubiquitin Chain Assembly Complex) as a new regulator of antigen receptor mediated a NF-κB ctivation and ABC DLBCL survival. Then, we screened a library of one thousand two hundred chemical compounds on DLBCL viability and identified one compound selectively toxic in vitro for the ABC DLBCL subtype. This compound induced ABC DLBCL apoptosis without affected NF-κB signaling. In the future, this compound could be used as a new therapeutic compound for ABC DLBCL.

Title Complex preoperative brain tumor imaging Abstract The differentiation of glioblastoma, metastases and brain lymphoma using modern diagnostic imaging methods has a major impact on the strategy of further diagnostic examinations and treatment. In a group of 67 patients with glioblastoma and 31 with cerebral metastasis, the ability to differentiate them according to the evaluation of perfusion parameters changes in peritumoral white matter by T1 dynamic post-contrast magnetic resonance imaging was verified, with the positive predictive value in glioblastoma detection up to 91%. In a group of 36 brain lymphoma patients the importance of imaging submodalities and contribution of a complex magnetic resonance imaging protocol to detect lymphoma up to 80% were evaluated. Key words brain, glioblastoma, lymphoma, magnetic resonance imaging, neoplasm metastasis

The human positive regulatory domain I binding factor 1 (PRDI-BF1/PRDM1) promotes differentiation of mature B cells into antibody secreting plasma cells. In contrast ectopic expression of PRDM1 in lymphoma cells can lead to inhibition of proliferation or apoptosis. However, little is currently known about the regulation of PRDM1. The first study presented demonstrates that in lymphoma cells stimulation through the B cell receptor rapidly induces endogenous PRDM1 at the level of transcription. This study provides evidence that the PRDM1 promoter is preloaded and poised for activation in the B cell lines. The transcription factor PU.1 is shown to be required for B cell receptor induced expression of PRDM1 in lymphoma cells and in PU.1 positive myeloma cells. Furthermore, activation is associated with loss of the co-repressor TLE4 from the PU.1 complex. The second study establishes the requirement for PRDM1 in Mantle cell lymphoma (MCL) response to Bortezomib. MCL, an aggressive form of B cell lymphoma, has poor disease- free survival rate. The proteasome inhibitor, Bortezomib, is approved for treatment of relapsed and refractory MCL. However, the precise mechanism of action of Bortezomib is not well understood. Bortezomib rapidly induces transcription of PRDM1 along with apoptosis in MCL cell lines and primary MCL tumor samples. Knockdown of PRDM1 inhibits Bortezomib-induced apoptosis, while ectopic expression of PRDM1 alone leads to apoptosis in MCL. MKI67 and PCNA, which are required for proliferation and survival, were identified as novel direct targets of PRDM1 in MCL. Chromatin immunoprecipitation and knockdown studies reveal specific repression of MKI67 and PCNA is mediated by PRDM1 in response to Bortezomib. Furthermore promoter studies demonstrate that PRDM1 functions through a specific site in the proximal promoter region of PCNA and through a distal upstream repression domain on the MKI67 promoter. Together these findings establish PRDM1 as a key mediator of Bortezomib activity in MCL through suppression of proliferation and survival genes. The third study presented demonstrates use of Tandem affinity purification technique followed by mass spectrometry to identify PRDM1 and Reptin52 protein interactions. The observations in this study provide preliminary evidence of novel mechanism of regulation of PRDM1 protein function.