Abstract 2655: The GPCR OR13A1 is essential for lymphoma cells
Authors: Sartori Giulio , Cascione Luciano , Matkovic Milos , Matsunami Hiroaki , Cavalli Andrea , Bertoni Francesco 
Published: June 2022

Abstract
Background. G protein-coupled receptors (GPCRs) are integral membrane proteins that mediate cellular responses to endogenous (amines, cations, lipids, peptides, glycoproteins) and exogenous (light, tastants, odorants) stimuli. Altered signaling pathways associated with GPCRs are implicated in the pathophysiology of various diseases, such as CXCR3/4/5, S1PR1/2/3, GPR34 in lymphomas. Olfactory receptors (ORs) are GPCRs, initially identified and characterized for their expression in olfactory neurons but now recognized as expressed in different 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. OR13A1 has been included in the double-hit expression signature reported in diffuse large B cell lymphoma (DLBCL) (Ennishi et al 2019). 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 DLBCL cell lines. Gene expression data for clinical samples obtained from public dataset phs001444.v2.p1. OR13A1 silencing performed with both siRNAs (OCI-Ly1, U2932) and doxycycline-inducible shRNAs (U2932); viability assessed after 3 days using MTT and for longer with Incucyte live imaging. Computer modelling performed based on available ligands for the murine orthologue Olfr211 and similar known GPCRs structure.
Results. Only one OR per cell line was usually expressed, as reported for olfactory cells. Using RNA-Seq and real-time PCR, OR13A1 gene appeared the most abundantly expressed in lymphomas cell lines compared to others ORs. Its expression was seen in 35/47 B cell lymphoma lines, with higher expression in germinal center B cell (GCB) DLBCL than activated B cell like (ABC) DLBCL (P 0.03). A similar pattern was observed in patients: higher expression in GCB than ABC and in EZB than MCD (P &lt; 0.001). OR13A1 also appeared higher in normal GC cells than in naïve and memory B cells. Among GCB DLBCL patients, OR13A1 expression was associated with inferior outcome. Silencing of OR13A1 with siRNAs in GCB and ABC DLBCL cells caused &gt; 50% reduction in cell viability, and pERK downregulation. Viability data were confirmed using a doxycycline-inducible shRNA system and 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, higher in GCB than ABC DLBCL and with a possible impact on clinical outcome. Genetic and chemical experiments showed that this GPCR has an essential function in lymphoma cells and could represent a novel therapeutic target.
Citation Format: Giulio Sartori, Luciano Cascione, Milos Matkovic, Hiroaki Matsunami, Andrea Cavalli, Francesco Bertoni. The GPCR OR13A1 is essential for lymphoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2655.