Loss of RAF kinase inhibitor protein is involved in myelomonocytic differentiation and aggravates RAS-driven myeloid leukemogenesis
Veronica Caraffini,
Olivia Geiger,
Angelika Rosenberger,
Stefan Hatzl,
Bianca Perfler,
Johannes L. Berg,
Clarice Lim,
Herbert Strobl,
Karl Kashofer,
Silvia Schauer,
Christine Beham-Schmid,
Gerald Hoefler,
Klaus Geissler,
Franz Quehenberger,
Walter Kolch,
Dimitris Athineos,
Karen Blyth,
Albert Wölfler,
Heinz Sill,
Armin Zebisch
Affiliations
Veronica Caraffini
Division of Hematology, Medical University of Graz, Graz, Austria
Olivia Geiger
Division of Hematology, Medical University of Graz, Graz, Austria
Angelika Rosenberger
Division of Hematology, Medical University of Graz, Graz, Austria
Stefan Hatzl
Division of Hematology, Medical University of Graz, Graz, Austria
Bianca Perfler
Division of Hematology, Medical University of Graz, Graz, Austria
Johannes L. Berg
Division of Hematology, Medical University of Graz, Graz, Austria
Clarice Lim
Otto Loewi Research Center, Immunology and Pathophysiology, Medical University of Graz, Graz, Austria
Herbert Strobl
Otto Loewi Research Center, Immunology and Pathophysiology, Medical University of Graz, Graz, Austria
Karl Kashofer
Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
Silvia Schauer
Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
Christine Beham-Schmid
Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
Gerald Hoefler
Diagnostic and Research Institute of Pathology, Medical University of Graz, Graz, Austria
Klaus Geissler
5th Medical Department with Hematology, Oncology and Palliative Medicine, Hospital Hietzing, Vienna, Austria;Sigmund Freud University, Vienna, Austria
Franz Quehenberger
Institute of Medical Informatics, Statistics and Documentation, Medical University of Graz, Graz, Austria
Walter Kolch
Systems Biology Ireland and Conway Institute, University College Dublin, Dublin, Ireland
Dimitris Athineos
Cancer Research UK Beatson Institute, Glasgow, UK
Karen Blyth
Cancer Research UK Beatson Institute, Glasgow, UK
Albert Wölfler
Division of Hematology, Medical University of Graz, Graz, Austria
Heinz Sill
Division of Hematology, Medical University of Graz, Graz, Austria
Armin Zebisch
Division of Hematology, Medical University of Graz, Graz, Austria;Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Pharmacology, Medical University of Graz, Graz, Austria
RAS-signaling mutations induce the myelomonocytic differentiation and proliferation of hematopoietic stem and progenitor cells. Moreover, they are important players in the development of myeloid neoplasias. RAF kinase inhibitor protein (RKIP) is a negative regulator of RAS-signaling. As RKIP loss has recently been described in RAS-mutated myelomonocytic acute myeloid leukemia, we now aimed to analyze its role in myelomonocytic differentiation and RAS-driven leukemogenesis. Therefore, we initially analyzed RKIP expression during human and murine hematopoietic differentiation and observed that it is high in hematopoietic stem and progenitor cells and lymphoid cells but decreases in cells belonging to the myeloid lineage. By employing short hairpin RNA knockdown experiments in CD34+ umbilical cord blood cells and the undifferentiated acute myeloid leukemia cell line HL-60, we show that RKIP loss is indeed functionally involved in myelomonocytic lineage commitment and drives the myelomonocytic differentiation of hematopoietic stem and progenitor cells. These results could be confirmed in vivo, where Rkip deletion induced a myelomonocytic differentiation bias in mice by amplifying the effects of granulocyte macrophage-colony-stimulating factor. We further show that RKIP is of relevance for RAS-driven myelomonocytic leukemogenesis by demonstrating that Rkip deletion aggravates the development of a myeloproliferative disease in NrasG12D-mutated mice. Mechanistically, we demonstrate that RKIP loss increases the activity of the RAS-MAPK/ERK signaling module. Finally, we prove the clinical relevance of these findings by showing that RKIP loss is a frequent event in chronic myelomonocytic leukemia, and that it co-occurs with RAS-signaling mutations. Taken together, these data establish RKIP as novel player in RAS-driven myeloid leukemogenesis.