TY - JOUR AU - Shiori Kinoshita, AU - Takashi Ishida, AU - Asahi Ito, AU - Tomoko Narita, AU - Ayako Masaki, AU - Susumu Suzuki, AU - Takashi Yoshida, AU - Masaki Ri, AU - Shigeru Kusumoto, AU - Hirokazu Komatsu, AU - Norio Shimizu, AU - Hiroshi Inagaki, AU - Taruho Kuroda, AU - Arne Scholz, AU - Ryuzo Ueda, AU - Takaomi Sanda, AU - Shinsuke Iida, PY - 2018/11/30 Y2 - 2024/03/28 TI - Cyclin-dependent kinase 9 as a potential specific molecular target in NK-cell leukemia/lymphoma JF - Haematologica JA - haematol VL - 103 IS - 12 SE - Articles DO - 10.3324/haematol.2018.191395 UR - https://haematologica.org/article/view/8702 SP - 2059-2068 AB - BAY 1143572 is a highly selective inhibitor of cyclin-dependent kinase 9/positive transcription elongation factor b. It has entered phase I clinical studies. Here, we have assessed the utility of BAY 1143572 for treating natural killer (NK) cell leukemias/lymphomas that have a poor prognosis, namely extranodal NK/T-cell lymphoma, nasal type and aggressive NK-cell leukemia, in a preclinical mouse model in vivo as well as in tissue culture models in vitro. Seven NK-cell leukemia/lymphoma lines and primary aggressive NK-cell leukemia cells from two individual patients were treated with BAY 1143572 in vitro. Primary tumor cells from an aggressive NK-cell leukemia patient were used to establish a xenogeneic murine model for testing BAY 1143572 therapy. Cyclin-dependent kinase 9 inhibition by BAY 1143572 resulted in prevention of phosphorylation at the serine 2 site of the C-terminal domain of RNA polymerase II. This resulted in lower c-Myc and Mcl-1 levels in the cell lines, causing growth inhibition and apoptosis. In aggressive NK-cell leukemia primary tumor cells, exposure to BAY 1143572 in vitro resulted in decreased Mcl-1 protein levels resulting from inhibition of RNA polymerase II C-terminal domain phosphorylation at the serine 2 site. Orally administering BAY 1143572 once per day to aggressive NK-cell leukemia-bearing mice resulted in lower tumor cell infiltration into the bone marrow, liver, and spleen, with less export to the periphery relative to control mice. The treated mice also had a survival advantage over the untreated controls. The specific small molecule targeting agent BAY1143572 has potential for treating NK-cell leukemia/lymphoma. ER -