title: In vitro and in vivo effects of KT6352, a derivative of indolocarbazole compounds, on murine megakaryocytopoiesis.
abstract: We investigated the in vitro and in vivo effects of KT6352, a derivative of indolocarbazole compound, on murine megakaryocytopoiesis. When serum-free megakaryocyte (Meg) colony assay was performed with 100 U/mL of recombinant mouse interleukin-3 (rmIL-3), the addition of 1x10(-11)M to 1x10(-9)M of KT6352 increased the number of Meg colonies. An additional increase of Meg colonies by KT6352 was observed in the serum-free culture containing rmIL-3 plus recombinant mouse interleukin-6 or rmIL-3 plus recombinant mouse stem cell factor. KT6352 did not stimulate Meg colony formation without rmIL-3. When KT6352 was administered intraperitoneally to normal BALB/c male mice at a dose of 10 mg/kg daily for 5 consecutive days, a 2.1-fold increase in the platelet count was observed on day 14, and the prolonged thrombocytopoiesis was detectable from 9 to 27 days after KT6352 administration. A marked increase in the white blood cell count was also observed from 5 to 14 days after KT6352 treatment. Before the gradual increase of platelet counts, 8 days after KT6352 administration, a marked increase in the number of colony-forming units of megakaryocytes (CFU-Megs) in bone marrow and spleen was observed, and a substantial increase in the number of splenic CFU-Megs was observed 14 and 23 days after KT6352 administration. Bone marrow Meg ploidy analysis by two-color flow cytometry showed a shift in the modal ploidy class from 16 to 32 and an increase in the frequency of 64 cells in KT6352-treated mice. These results suggest a possible therapeutic benefit of KT6352 in the management of thrombocytopenia.
authors.affiliation: Pharmaceutical Research Laboratories, Kyowa Hakko Co., Ltd., Shizuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shiotsu
authors.forename: S
authors.initials: S
authors.lastname: Akinaga
authors.forename: K
authors.initials: K
authors.lastname: Yamashita
authors.forename: C
authors.initials: C
authors.lastname: Murakata
authors.forename: T
authors.initials: T
authors.lastname: Tamaoki
authors.forename: Y
authors.initials: Y
authors.lastname: Ishida
authors.forename: S
authors.initials: S
authors.lastname: Kuriya
authors.forename: M
authors.initials: M
authors.lastname: Teramura
authors.forename: H
authors.initials: H
authors.lastname: Mizoguchi
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects; D002227:Carbazoles / Q000494:pharmacology*; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006410:Hematopoiesis / Q000187:drug effects*; D007211:Indoles / Q000494:pharmacology*; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D007958:Leukocyte Count; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D010976:Platelet Count; D011003:Ploidies; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000494:pharmacology; D013154:Spleen / Q000166:cytology / Q000187:drug effects; D019311:Staurosporine / Q000494:pharmacology
chemical_list: D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D007377:Interleukin-3; D015850:Interleukin-6; C116130:KT-6352; D011994:Recombinant Proteins; D011493:Protein Kinase C; D019311:Staurosporine