sphingosine-1-phosphate and Lymphoma--Large-B-Cell--Diffuse

Although the over-expression of angiogenic factors is reported in diffuse large B-cell lymphoma (DLBCL), the poor response to anti-VEGF drugs observed in clinical trials suggests that angiogenesis in these tumours might be driven by VEGF-independent pathways. We show that sphingosine kinase-1 (SPHK1), which generates the potent bioactive sphingolipid sphingosine-1-phosphate (S1P), is over-expressed in DLBCL. A meta-analysis of over 2000 cases revealed that genes correlated with SPHK1 mRNA expression in DLBCL were significantly enriched for tumour angiogenesis meta-signature genes; an effect evident in both major cell of origin (COO) and stromal subtypes. Moreover, we found that S1P induces angiogenic signalling and a gene expression programme that is present within the tumour vasculature of SPHK1-expressing DLBCL. Importantly, S1PR1 functional antagonists, including Siponimod, and the S1P neutralising antibody, Sphingomab, inhibited S1P signalling in DLBCL cells in vitro. Furthermore, Siponimod, also reduced angiogenesis and tumour growth in an S1P-producing mouse model of angiogenic DLBCL. Our data define a potential role for S1P signalling in driving an angiogenic gene expression programme in the tumour vasculature of DLBCL and suggest novel opportunities to target S1P-mediated angiogenesis in patients with DLBCL.

Topics: Animals; Cell Line, Tumor; Computational Biology; Disease Models, Animal; Endothelial Cells; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Lymphoma, Large B-Cell, Diffuse; Lysophospholipids; Mice; Neovascularization, Pathologic; RNA, Messenger; Signal Transduction; Sphingosine; Transcriptome

Sphingosine-1-phosphate (S1P) is a potent lipid mediator that is produced during the metabolism of sphingolipid by sphingosine kinase. S1P has been implicated in the migration and trafficking of lymphocytes and several lymphoid malignancies through S1P receptors. Moreover, the overexpression of sphingosine-1-phosphate receptor 1 (S1PR1) has been correlated with the constitutive activation of signal transducer and activator of transcription (STAT)3 and poor prognosis of diffuse large B-cell lymphoma (DLBCL). Thus, in this study, we examined the expression of S1PR1 in 198 DLBCL samples collected from nodal and various extranodal sites and sub-classified formalin-fixed paraffin-embedded tissue samples into germinal centre B-cell-like (GCB) and non-GCB subgroups using immunohistochemistry. These analyses showed S1PR1 overexpression in 15·7% of all cases with DLBCL and in 54·2% of 24 cases with primary testicular (PT)-DLBCL; S1PR1 expression correlated with S1PR1mRNA expression and STAT3 phosphorylation in fresh samples. Analyses of data from a single institution suggested that S1PR1 overexpression was an independent negative prognostic marker in 68 patients with DLBCL of clinical stages I and II. The present high prevalence of S1PR1 overexpression warrants the consideration of PT-DLBCL as a distinct disease subtype and suggests the potential of the S1P/S1PR1 axis as a therapeutic target.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers; Female; Gene Expression Regulation, Neoplastic; Germinal Center; Humans; Immunohistochemistry; Lymphoma, Large B-Cell, Diffuse; Lysophospholipids; Male; Middle Aged; Phosphorylation; Prognosis; Receptors, Lysosphingolipid; RNA, Messenger; Sphingosine; STAT3 Transcription Factor; Testicular Neoplasms