The Genetic Basis of Hepatosplenic T-cell Lymphoma

Hepatosplenic T cell lymphoma (HSTL) is a rare and lethal lymphoma; the genetic drivers of this disease are unknown. Through whole exome sequencing of 68 HSTLs, we define recurrently mutated driver genes and copy number alterations in the disease. Chromatin modifying genes including SETD2, INO80 and ARID1B were commonly mutated in HSTL, affecting 62% of cases. HSTLs manifest frequent mutations in STAT5B (31%), STAT3 (9%), and PIK3CD (9%) for which there currently exist potential targeted therapies. In addition, we noted less frequent events in EZH2, KRAS and TP53. SETD2 was the most frequently silenced gene in HSTL. We experimentally demonstrated that SETD2 acts as a tumor suppressor gene. In addition, we found that mutations in STAT5B and PIK3CD activate critical signaling pathways important to cell survival in HSTL. Our work thus defines the genetic landscape of HSTL and implicates novel gene mutations linked to HSTL pathogenesis and potential treatment targets

Modulation des propriétés anti-tumorales de TRAIL dans les lymphomes folliculaires (rôle du microenvironnement ganglionnaire)

Les lymphomes folliculaires (LF) issus du centre germinatif sont indolents et caractérisés pour 80% d entre eux par une translocation chromosomique t(14,18) conduisant à la surexpression de l oncogène Bcl2. Dans cette pathologie, les cellules tumorales dépendent pour leur survie des autres cellules du microenvironnement ganglionnaire (MG). L amélioration des thérapies pour lutter efficacement contre les LF, ne permet pas de guérir les formes avancées de cette maladie. Ainsi, la recherche de nouvelles molécules anti-tumorales demeure primordiale. TRAIL, un membre de la famille des TNF, apparaît comme une molécule prometteuse dans cette lutte anti-tumorale. Le but de ce travail a consisté à étudier les effets du MG sur l action de TRAIL dans le LF. Nos résultats montrent que le stroma et les lymphocytes TFH, cellules importantes du MG, protègent les lymphocytes B tumoraux de l action de TRAIL, en modulant des molécules cibles de la voie NFkappaB et en modulant l activité de l enzyme COX-2. Il est donc crucial de prendre en compte l impact du MG stromal, hématopoïétique et cytokinique dans le développement de nouveaux traitements anti-lymphomateux.Follicular Lymphomas (FL) are indolent non-Hodgkin lymphomas derived from germinal centers. There are characterised by a t(14,18) chromosomal translocation responsible for the overexpression of the oncoprotein, Bcl-2. In this pathology, tumor B cell survival is linked to the microenvironment of the lymph node (LNM). None of standard therapies are curative against FL, especially in case of a multi-recurrent disease. Then, innovative approaches are urgently needed. The TNF family member, TRAIL, is emerging as a promising cytotoxic molecule for antitumor therapies. In consequence, the aim of this work was to investigate TRAIL-mediated apoptosis in FL B cells of the LNM in this response. We show with clear evidence that stromal cells and TFH lymphocytes, which correspond to key cellular partners of the LNM, protect tumour B cell from TRAIL-induced. This protection is mediated by NFkappaB and COX-2 activation. It is then crucial to take impact of the stromal, haematopoietic and cytokinic microenvironment present in germinal center in new anti-lymphoma treatments.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Sensitivity of prostate cells to TRAIL-induced apoptosis increases with tumor progression: DR5 and caspase 8 are key players.

International audienceBACKGROUND: As advanced prostate cancers are resistant to currently available chemotherapies, we evaluated the cytotoxic effect of TNF-related apoptosis-inducing ligand (TRAIL) and characterized the involvement of its five receptors DR4, DR5, DcR1, DcR2, and osteoprotegerin (OPG) and of the death-inducing signaling complex (DISC)-forming proteins caspase 8 and c-FLIP in prostate cell lines. METHODS: We used six prostate cell lines, each corresponding to a particular stage in prostate tumorigenesis, and analyzed TRAIL sensitivity in relation to TRAIL receptors' expression. RESULTS: TRAIL sensitivity was correlated with tumor progression and DR5 expression levels and apoptosis was exclusively mediated by DR5. DcR2 was significantly more abundant in tumor cells than in non-neoplastic ones and may contribute to partial resistance to TRAIL in some prostate tumor cells. Conversely, non-tumoral cells secreted high levels of OPG, which can protect them from apoptosis. Finally, caspase 8 expression levels were as DR5 directly correlated to TRAIL sensitivity in prostate tumor cells. CONCLUSION: TRAIL-induced apoptosis is closely related to the balanced expression of its different receptors in prostate cancer cells and their modulation could be of potential clinical value for advanced tumor treatment

CD40 ligand protects from TRAIL-induced apoptosis in follicular lymphomas through NF-kappaB activation and up-regulation of c-FLIP and Bcl-xL.

International audienceThe TNF family member TRAIL is emerging as a promising cytotoxic molecule for antitumor therapy. However, its mechanism of action and the possible modulation of its effect by the microenvironment in follicular lymphomas (FL) remain unknown. We show here that TRAIL is cytotoxic only against FL B cells and not against normal B cells, and that DR4 is the main receptor involved in the initiation of the apoptotic cascade. However, the engagement of CD40 by its ligand, mainly expressed on a specific germinal center CD4(+) T cell subpopulation, counteracts TRAIL-induced apoptosis in FL B cells. CD40 induces a rapid RNA and protein up-regulation of c-FLIP and Bcl-x(L). The induction of these antiapoptotic molecules as well as the inhibition of TRAIL-induced apoptosis by CD40 is partially abolished when NF-kappaB activity is inhibited by a selective inhibitor, BAY 117085. Thus, the antiapoptotic signaling of CD40, which interferes with TRAIL-induced apoptosis in FL B cells, involves NF-kappaB-mediated induction of c-FLIP and Bcl-x(L) which can respectively interfere with caspase 8 activation or mitochondrial-mediated apoptosis. These findings suggest that a cotreatment with TRAIL and an inhibitor of NF-kappaB signaling or a blocking anti-CD40 Ab could be of great interest in FL therapy

Ethanol induces oxidative stress in primary rat hepatocytes through the early involvement of lipid raft clustering.

International audienceThe role of the hepatocyte plasma membrane structure in the development of oxidative stress during alcoholic liver diseases is not yet fully understood. Previously, we have established the pivotal role of membrane fluidity in ethanol-induced oxidative stress, but no study has so far tested the involvement of lipid rafts. In this study, methyl-beta-cyclodextrin or cholesterol oxidase, which were found to disrupt lipid rafts in hepatocytes, inhibited both reactive oxygen species production and lipid peroxidation, and this suggested a role for these microstructures in oxidative stress. By immunostaining of lipid raft components, a raft clustering was detected in ethanol-treated hepatocytes. In addition, we found that rafts were modified by formation of malondialdehyde adducts and disulfide bridges. Interestingly, pretreatment of cells by 4-methyl-pyrazole (to inhibit ethanol metabolism) and various antioxidants prevented the ethanol-induced raft aggregation. In addition, treatment of hepatocytes by a stabilizing agent (ursodeoxycholic acid) or a fluidizing compound [2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanoate] led to inhibition or enhancement of raft clustering, respectively, which pointed to a relationship between membrane fluidity and lipid rafts during ethanol-induced oxidative stress. We finally investigated the involvement of phospholipase C in raft-induced oxidative stress upon ethanol exposure. Phospholipase C was shown to be translocated into rafts and to participate in oxidative stress by controlling hepatocyte iron content. Conclusion: Membrane structure, depicted as membrane fluidity and lipid rafts, plays a key role in ethanol-induced oxidative stress of the liver, and its modulation may be of therapeutic relevance

COX-2 independent effects of Celecoxib sensitize Lymphoma B cells to TRAIL-mediated apoptosis.

4 supplemental figures and supplemental methodsInternational audiencePURPOSE: Despite therapeutic advances, Non-Hodgkin lymphomas (NHL) remain incurable. They form a group of neoplasms strongly dependent on their inflammatory microenvironment, which plays an important supportive role in tumor B-cell survival and in the resistance to anti-tumor immune response. New therapies must consider both tumor cells and their surrounding microenvironment EXPERIMENTAL DESIGN: Stromal cells, derived from bone marrow or lymph nodes, and B cells from follicular lymphoma patients were co-cultured or cultured alone with Celecoxib treatment, a non-steroidal anti-inflammatory drug and/or TRAIL, a promising cytotoxic molecule for cancer therapy. RESULTS: In this study, we show that follicular lymphoma (FL) stromal cells produce large amounts of PGE2. This production is abrogated after Celecoxib treatment, targeting the COX-2 isoenzyme involved in PGE2 synthesis. Furthermore, we demonstrate that Celecoxib increases apoptosis in NHL B-cell lines and in primary FL B-cells co-cultured with stromal cells, but independently of the PGE2/COX-2 axis. Finally, Celecoxib increases the apoptotic activity of TRAIL. We provide evidence that Celecoxib affects proliferation and sensitizes NHL B-cell lines to apoptosis through COX-2 independent effects by slowing down the cell cycle and decreasing the expression of survival proteins, such as Mcl-1. CONCLUSIONS: These data suggest new potent strategies for NHL therapy combining drugs targeting both tumour B cells and survival signals provided by the tumor microenvironment

ROQUIN/RC3H1 alterations are not found in angioimmunoblastic T-cell lymphoma.

Angioimmunoblastic T-cell Lymphoma (AITL) is one of the most frequent T-cell lymphoma entities. Follicular helper T lymphocytes (TFH) are recognized as the normal cellular counterpart of the neoplastic component. Despite a clonal T-cell feature and few described recurrent cytogenetic abnormalities, a driving oncogenic event has not been identified so far. It has been recently reported that in mice, heterozygous inactivation of Roquin/Rc3h1, a RING type E3 ubiquitine ligase, recapitulates many of the clinical, histological, and cellular features associated with human AITL. In this study we explored whether ROQUIN alterations could be an initial event in the human AITL oncogenic process. Using microarray and RT-PCR analyses, we investigated the levels of ROQUIN transcripts in TFH tumor cells purified from AITL (n = 8) and reactive tonsils (n = 12) and found similar levels of ROQUIN expression in both. Moreover, we also demonstrated that ROQUIN protein was expressed by AITL TFH (PD1+) cells. We then analysed ROQUIN coding sequence in 12 tumor cell-rich AITL samples and found no mutation in any of the samples. Finally, we analysed the expression of MiR101, a putative partner of ROQUIN involved in the modulation of ICOS expression and found similar levels of expression in tumor and reactive TFH. Altogether, this study shows that neither alteration of ROQUIN gene nor deregulation of miR101 expression is likely to be a frequent recurrent event in AITL