Abstract A05: Olfactory receptors as a new therapeutic target in lymphomas

Abstract

Abstract Background. Diffuse large B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) are aggressive lymphomas in which up to 40% of patients are still in need of therapy. G protein-coupled receptors (GPCRs) are integral membrane proteins that mediate cellular responses to endogenous and exogenous stimuli and are implicated in the pathophysiology of various diseases: CXCR3/4/5, S1PR1/2/3, or GPR34 are GPCRs already studied in lymphomas. The olfactory receptors (ORs) are also GPCRs, initially identified and characterized for their expression in olfactory cells but now shown to be expressed in various tissues. OR51E1 is known as prostate-specific G protein-coupled receptor 2 (PSGR2) due to its expression in prostate cancer, OR2B6 and OR2W3 are expressed in breast cancer, and OR51E1 in melanoma. Here, we studied OR13A1 in lymphoma cell lines and clinical specimens. Methods. RNA-Seq and real-time PCR for evaluating the expression of ORs in lymphoma cell lines. Gene expression data for clinical samples were obtained from public datasets. OR13A1 silencing was performed with both siRNAs (OCI-Ly1 and U2932) and doxycycline-inducible shRNAs (U2932 and VAL); viability was assessed after 3 days using MTT and even longer with live imaging. Computer modelling was performed using available ligands for the murine orthologue Olfr211. Results. Various ORs were expressed across a large panel of B cell lymphoma cell lines. In particular, OR13A1 was expressed in 35/47 cell lines and, mostly, derived from DLBCL and MCL. Among DLBCL, the expression was higher in cell lines derived from the germinal center (GC) B-cell type (GCB) rather than from activated B cell like (ABC) DLBCL (P value = 0.03). A similar pattern was observed in DLBCL patients: higher expression in GCB than ABC and in EZB than MCD (P < 0.001). OR13A1 also appeared higher in normal GC cells than in naïve and memory B cells. OR13A1 expression appears to identify GCB DLBCL (P value = 0.009) and MCL (P value = 0.006) patients with inferior outcome. Silencing of OR13A1 with siRNAs in GCB and ABC DLBCL cells (OCI-Ly1 and U2932) caused > 50% reduction in cell viability, and downregulation of pERK levels. Viability data were confirmed using a doxycycline-inducible shRNA system and an Incucyte live cell imaging instrument. Natural compounds reported as ligands for the murine orthologue Olfr211 or in silico identified to bind as agonists (ex: tyramine) increased cell line growth and compounds predicted to bind as antagonists (ex: cyclohexanone) decreased the cell viability in the presence but not in the absence of the GPCR. Conclusion. OR13A1 gene appeared more abundantly expressed in lymphomas compared to others ORs, in particular it was more expressed in MCL and in GCB DLBCL with a possible impact on clinical outcome. Genetic and chemical experiments showed that this GPCR has an essential function in lymphoma cells and represents a novel therapeutic target. Citation Format: Giulio Sartori, Luciano Cascione, Milos Matkovic, Hiro Matsunami, Andrea Cavalli, Francesco Bertoni. Olfactory receptors as a new therapeutic target in lymphomas [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A05.