G PROTEIN-COUPLED RECEPTOR KINASE 2 (GRK2) MODULATES LEUKEMIC CELL HOMING AND ACTIVATION IN B-CELL CHRONIC LYMPHOCYTIC LEUKAEMIA (CLL)

CASSARINO C; COLADO, ANA; SARAPURA MARTÍNEZ, VALERIA; BERTINI M; FEDERICO FUENTES; BEZARES, FERNANDO; VERMEULEN M; GIORDANO , M; GAMBERALE, ROMINA; BORGE, M.

San Luis

Congreso; LXXI Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2023

CLL leukemic cell proliferation and resistance to therapy occur within lymphoidtissues, supporting the idea that their presence within this tumourmicroenvironment contributes to disease progression and relapse. GRK2 plays acentral role in B cell homing to lymphoid organs by inducing Sphingosine-1phosphate receptor-1 (S1PR1) downregulation, which allows lymphocytes toovercome the S1P-mediated retention in blood necessary to enter into lymphoidtissues. In addition, GRK2 has been implicated in signalling pathways related tocancer progression. The role of GRK2 on CLL cell migration, activation andsurvival has not been studied yet.Leukemic cells were obtained from CLL patients´ peripheral blood (PB). GRK2expression was evaluated by western blot and qRT-PCR. Normal B cells fromage-matched healthy donors (HD) were used as control. CLL cell activation andviability were evaluated by flow cytometry (FC). In vitro migration was evaluatedwith the transwell cell migration assay. Primary murine leukemic cells wereobtained from Eµ-TCL-1 mice. GRK2-deficient murine leukemic cells (GRK2KO)were generated by CRISPR/Cas9 editing on the mouse cell line TCL1-355 TKO.For in vivo migration assays, GRK2KO or MOCK (control) cells were labeled withCTV or CFSE, mixed in a ratio 1:1 and injected through the tail vein. After 20hours, their localization in PB, bone marrow (BM) and spleen (SP) was evaluatedby FC. GraphPad Prism software was used for statistical analysis.We found that leukemic cells from CLL patients (n=20) express similar levels ofGRK2 as B cells from HD (n=6). The presence of a chemical GRK2 inhibitor,CMPD101, impaired the up-regulation of CD86 expression on CLL cells activatedthrough the BCR (n=5, p