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Imatinib mesylate (IM) and other BCR-ABL tyrosine kinase inhibitors (TKIs) have improved chronic myeloid leukemia (CML) patient survival markedly but fail to eradicate quiescent CML leukemia stem cells (LSCs). Thus, strategies targeting LSCs are required to induce long-term remission and achieve cure. Here, we investigated the ability of topoisomerase II (Top II) inhibitor etoposide (Eto) to target CML LSCs. Treatment with Eto combined with IM markedly induced apoptosis in primitive CML CD34+CD38− stem cells resistant to eradication by IM alone, but not in normal hematopoietic stem cells, CML and normal mature CD34− cells, and other leukemia and lymphoma cell lines. The interaction of IM and Eto significantly inhibited phosphorylation of PDK1, AKT, GSK3, S6, and ERK proteins; increased the expression of pro-apoptotic gene Bax; and decreased the expression of anti-apoptotic gene c-Myc in CML CD34+ cells. Top II inhibitors treatment represents an attractive approach for targeting LSCs in CML patients undergoing TKIs monotherapy. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of etoposide (ETO) on elimination of chronic myeloid leukemia (CML) stem cells by imatinib mesylate(IM) in vivo., Methods: SCL-tTA/BCR-ABL mice were used as CML animal model. Flow cytometry was used to assess the effect of ETO alone or in combination with IM on the number of leukemia stem cell （LSC） in bone marrow and spleen, and peripheral blood neutrophils in CML mice and normal control FVB mice., Results: The results showed that in CML mice, the number and proportion of LSC in bone marrow and the proportion of neutrophils in peripheral blood decreased significantly after ETO and IM combined treatment, and the degree of decrease was more significant than that of both alone. While in wild type FVB mice, the combination of ETO and IM showed no significant effect on the number and proportion of LSK cells in bone marrow and the proportion of neutrophils in spleen., Conclusion: ETO can selectively enhance elimination of CML LSC by IM in vivo.

Objective: To construct recombinant expression plasmid with an antibacterial peptide (attacin) mature peptide gene from Musca domestica and express an antibacterial peptide attacin in Pichia pastoris., Methods: The coding region of attacin mature peptide was cloned into the expression vector pPIC9K. The recombinant plasmid was linearized by digestion with Sac I and transformed into P. pastoris GS115 by electroporation. The insert clones containing multiple copies were selected with geneticin, pha, enotype and PCR. The expression of P. pastoris GS115/pPIC9K-attacin were induced with methanol. The supernatant of the expressed protein was analyzed by SDS-PAGE and Western blotting. The anti-bacterial activity of expression product was analyzed by agarose diffusion assay., Results: The expression plasmid was constructed and transformed into P. pastoris GS115. SDS-PAGE and Western blotting analysis indicated that the recombinant containing recombinant plasmid pPIC9K-attacin expressed a Mr 22000 protein. The expression product inhibited the growth of E. coli K12D31., Conclusion: The attacin gene from Musca domestica has been expressed in P. pastoris.