125 Screening of Novel Mitotic Kinesin Eg5 Inhibitors in Human Cancer Cells

Abstract

Background: Thrombocytopenia is a common problem observed after chemoor/and radiotherapy in cancer patients. Chemotherapy-induced thrombocytopenia may reduce the frequency of drug dose and cause the treatment delays. The major treatment of thrombocytopenia is platelet transfusion. However, the transfusion may induce some side effects. It is also limited by supply and cost. Interleukin 11 (IL-11) is the only agent currently approved by FDA for treatment of thrombocytopenia. We have constructed the Hyper interleukin 11 (H11) which is composed of soluble IL-11 receptor alpha (sIL-11R) and IL-11. One of the potential applications of H11 is treatment of thrombocytopenia and/or ex vivo platelet production. The effects of H11 on megakaryopoiesis were studied. Materials and Methods: Lin-CD34+ cells were isolated from cord blood. The proliferation and differentiation of Lin-CD34 + cells after H11 stimulation were analyzed. For differentiation analysis cells phenotypes were evaluated by flow cytometry. Moreover, H11 activity was tested in colony forming cell assay for kind, number and size of formed colonies. Mk-CFU colonies were detected immunohistochemically. Results: H11 was more effective than recombinant human IL-11 (rhIL11) in enhancement of the Lin-CD34+ cells proliferation and differentiation into megakaryocytes (Mk). It induced higher expression of CD41a and CD61 antigens, resulting in the substantially larger population of CD34CD41aCD61 cells. H11 treatment led to increased number of small and mainly medium megakaryocyte colony formation (Mk-CFU). Moreover, it induced formation of a small number of large colonies, which were not observed following rhIL-11 treatment. Higher percentage of H11 derived Mk colonies released platelets like particles. Conclusions: H11 is a good novel candidate for treatment of thrombocytopenia and/or for ex vivo expansion of megakaryocytes and platelets production.