Dataset Information

HSP90 promotes Burkitt lymphoma cell survival by maintaining tonic B cell receptor signaling

ABSTRACT: Burkitt’s lymphoma (BL) is an aggressive B-cell neoplasm that is currently treated by intensive chemotherapy in combination with anti-CD20 antibodies. Because of their toxicity, current treatment regimens are often not suitable for elderly patients or for patients in developing countries where BL is endemic. Hence, there is a need for targeted therapies. In this study, we performed a compound screen in 17 BL cell lines to identify small molecule inhibitors affecting cell survival. We observed that, among other compounds, inhibitors of heat shock protein 90 (HSP90) induce apoptosis in BL cells in vitro at concentrations that did not affect normal B cells. By global proteomic and phosphoproteomic profiling, we found that in BL, HSP90 inhibition compromises activity of the pivotal B cell antigen receptor (BCR)-proximal effector spleen tyrosine kinase (SYK), which we identified as an HSP90 client protein. Consistently, expression of constitutively active TEL-SYK counteracted the apoptotic effect of HSP90 inhibition. Hence, our study provides a molecular rationale for the use of HSP90 inhibitors in the treatment of BL by demonstrating that HSP90 inhibition interferes with tonic BCR signaling and thus impairs BL cell survival.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): B Cell, Cell Culture

DISEASE(S): Lymphoma

SUBMITTER: Kuan-Ting Pan

LAB HEAD: Henning Urlaub

PROVIDER: PXD004181 | Pride | 2017-01-02

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	KT_Pan_010816_030816_DG75_Tel-SyK_proteome1.raw	Raw
	KT_Pan_010816_030816_DG75_Tel-SyK_proteome2.raw	Raw
	KT_Pan_010816_030816_Daudi_hsp90_proteome1.raw	Raw
	KT_Pan_010816_030816_Daudi_hsp90_proteome2.raw	Raw
	KT_Pan_010816_090816_DD_hsp90_pY_1-1.raw	Raw

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HSP90 promotes Burkitt lymphoma cell survival by maintaining tonic B-cell receptor signaling.

Walter Roland R Pan Kuan-Ting KT Doebele Carmen C Comoglio Federico F Tomska Katarzyna K Bohnenberger Hanibal H Young Ryan M RM Jacobs Laura L Keller Ulrich U Bönig Halvard H Engelke Michael M Rosenwald Andreas A Urlaub Henning H Staudt Louis M LM Serve Hubert H Zenz Thorsten T Oellerich Thomas T

Blood 20161115 5

Burkitt lymphoma (BL) is an aggressive B-cell neoplasm that is currently treated by intensive chemotherapy in combination with anti-CD20 antibodies. Because of their toxicity, current treatment regimens are often not suitable for elderly patients or for patients in developing countries where BL is endemic. Targeted therapies for BL are therefore needed. In this study, we performed a compound screen in 17 BL cell lines to identify small molecule inhibitors affecting cell survival. We found that i ...[more]

PMID: 28064214

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Project description:Background: Bromodomain and extra-terminal domain (BET) proteins and the spleen tyrosine kinase (SYK) represent promising targets in Diffuse large B-cell (DLBCL) and Burkitt’s lymphoma (BL). We evaluated the anti-lymphoma activity of the isoform specific bivalent BET inhibitor AZD5153 (AZD) and the pan-BET inhibitor I-BET151 (I-BET) as single agents and in combination with SYK inhibitor Entospletinib in vitro. Methods: Single agent exposures were evaluated on two DLBCL and two BL cell lines analyzing cell proliferation and metabolic activity. Proliferation, metabolic activity, apoptosis, cell cycle and morphology were investigated after combined AZD or I-BET and Ento exposure. RNAseq of combined AZD+Ento exposure was characterized in SU-DHL-4. Background: Bromodomain and extra-terminal domain (BET) proteins and the spleen tyrosine kinase (SYK) represent promising targets in Diffuse large B-cell (DLBCL) and Burkitt’s lymphoma (BL). We evaluated the anti-lymphoma activity of the isoform specific bivalent BET inhibitor AZD5153 (AZD) and the pan-BET inhibitor I-BET151 (I-BET) as single agents and in combination with SYK inhibitor Entospletinib in vitro. Methods: Single agent exposures were evaluated on two DLBCL and two BL cell lines analyzing cell proliferation and metabolic activity. Proliferation, metabolic activity, apoptosis, cell cycle and morphology were investigated after combined AZD or I-BET and Ento exposure. RNAseq of combined AZD+Ento exposure was characterized in SU-DHL-4. Results: Both BET inhibitors reduced cell proliferation/metabolic activity dose and time de-pendently. Combined BET and SYK inhibition enhanced the anti-proliferative effect and induc-ing a G0/G1 cell cycle arrest. SU-DHL-4 demonstrated a pronounced modulation of gene expres-sion by AZD, which was markedly increased by additional SYK inhibition. Functional enrich-ment analyses identified combination-specific GO terms related to cell division, transport and DNA replication. Genes such as PLEKHH3, MYB, SLC8A1, PARP9, HSPB1 and S100A4 were iden-tified as the presumable key regulators. Conclusion: Simultaneous inhibition of BET and SYK enhanced the anti-proliferative effects, and especially the combination-specific gene expression signature.

Project description:The B cell receptor (BCR) signaling, required for the survival and maturation of B cells, is a major deregulated pathway in B cell lymphomas. Several mutations are known to enhance the tonic BCR signal in Burkitt lymphomas (BL) or to mimic an activated receptor in some diffuse large B cell lymphomas (DLBCL). While the proximal events and kinases of the BCR signaling are well studied, less is known about the interactions of downstream effector pathways. In order to reach a less abstract description of this pathway we decided to employ the Modular Response Analysis-based modelling approach STASNet on more directly connected phosphorylation data. Using a Luminex proteomics platform we measured the phosphorylation of fourteen signaling and effector proteins after activating the B cell receptor (BCR) signaling and/or using inhibitors directed against seven intracellular signaling molecules in two independent Burkitt lymphoma cells (BL-2, BL-41). Application of a novel two step STASNet modelling pipeline unveiled novel feedback and crosstalk structures in the BCR-driven signaling network, including a crosstalk from p38 which negatively regulates MEK/ERK-activity in the presence of active BCR. Using Western Blot measurements, we verified and further characterized the p38-MEK/ERK crosstalk and demonstrated that it is a general mechanism in BL cells. Global Tandem Mass Tag (TMT) phosphoproteomic analysis on BL-2 cells found PI3K to be a major mediator of B-cell receptor signaling and manifested the p38-ERK crosstalk directly on ERK phosphosites and indirectly on seven bona fide ERK targets. We also noticed that the BL-2-learned pathway network structure was transferable to perturbation data from closely related BL-41 cells. Moreover, - compared to a literature-derived network - the BL-2-developed predictive pathway proved also to be a better starting point for network development in cells with aberrant BCR signaling in two representative cell lines derived from Diffuse large B cells (HBL-1, OCI-LY3). This indicates that models trained on activated B-cells are highly informative to be transferred to closely related cancer signaling network.