Phosphatase of regenerating liver-3 is expressed in acute lymphoblastic leukemia and mediates leukemic cell adhesion, migration and drug resistance

// Magnus A. Hjort 1, 2 , Pegah Abdollahi 1, 3 , Esten N. Vandsemb 1, 3 , Mona H. Fenstad 1, 3 , Bendik Lund 1, 2 , Tobias S. Slordahl 1, 4 , Magne Borset 1, 3 and Torstein B. Ro 1, 2 1 Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway 2 Children’s Clinic, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway 3 Department of Immunology and Transfusion Medicine, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway 4 Department of Hematology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway Correspondence to: Magnus A. Hjort, email: magnus.a.hjort@ntnu.no Keywords: PRL-3; acute lymphoblastic leukemia; migration; adhesion; drug resistance Received: October 11, 2017     Accepted: December 01, 2017     Published: December 13, 2017 ABSTRACT Phosphatase of regenerating liver-3 (PRL-3/PTP4A3) is upregulated in multiple cancers, including BCR-ABL1- and ETV6-RUNX-positive acute lymphoblastic leukemia (ALL). With this study, we aim to characterize the biological role of PRL-3 in B cell ALL (B-ALL). Here, we demonstrate that PRL-3 expression at mRNA and protein level was higher in B-ALL cells than in normal cells, as measured by qRT-PCR or flow cytometry. Further, we demonstrate that inhibition of PRL-3 using shRNA or a small molecular inhibitor reduced cell migration towards an SDF-1α gradient in the preB-ALL cell lines Reh and MHH-CALL-4. Knockdown of PRL-3 also reduced cell adhesion towards fibronectin in Reh cells. Mechanistically, PRL-3 mediated SDF-1α stimulated calcium release, and activated focal adhesion kinase (FAK) and Src, important effectors of migration and adhesion. Finally, PRL-3 expression made Reh cells more resistance to cytarabine treatment. In conclusion, the expression level of PRL-3 was higher in B-ALL cells than in normal cells. PRL-3 promoted adhesion, migration and resistance to cytarabine. PRL-3 may represent a novel target in the treatment of B-ALL.