| PostgraduateWang Wei Tutor Sun Bing-zhongDepartment of Hematology , Xijing Hospital , The fourth Military MedicalUniversity , Xi 'an,710032, Shanxi Province,ChinaChronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder due to an acquired abnormality in a pluripotential hematopoietic stem cell. CML is cytogenetically marked by the Philadelphia (Ph) chromosome, which originates from a reciprocal translocation between chromosome 9 and 22 and is molecularly marked a chimeric bcr-abl gene, resulting from juxta-positive of the abl proto-oncogene on chromosome 9 with the bcr gene, which is normally located on chromosome 22. The chimeric bcr-abl gene expression an 8.5kb hybrid mRNA transcript giving rise to a 210-KD fusion protein (Kltf**1) with increased tyrosine Chinese activity. P21O1"1"*1 play a key role in the pathogenesis of CML.SO far ,there is no effective treatmemt for CML.Allogeneic bone marrow transplatantion (allo-BMT) is the only treatment thus far shown to have curative potential in CML.However , a fatal complication often develops related to graft-versus-host disease(GVHD) in 30-35 percent of patients. In addition, the requirement for patients age and histocompatibility (only 30 percent patients can find a matched sibling donor) limit its applicability . The majority of patients are not eligible for this approach. Autologous bone marrow transplantation(ABMT) has a lower complication related to autografting than allo-BMT,,but in vitro purging efficiently of residual leukemia for prevention of relaps remains a problem to be resolved. Interferon has been used in CML for many years ,only 25-30 percent cases may get transient cytogenetic remission when given subcutaneously over a prolonged-6-period in high doses. Conventional chemotherapy can only obtain symptom remission. So it is important to find out new methods to effectively treat CML.As an important regulator in cell-cycle, CyclinDl plays a key role in Gl/S phase transition. Abnormal expression of CyclinDl gene and bcr-abl fusion gene both can impel CM1 progression. Tyrosine kinase inhibitor to bcr-abl can block signal transduction pathways, interfere with key metabolism enzyme, and can show the function of inducing apoptosis and differentiation .In this kind reagents, STI571 have been used in medical clinic with great achievement , but it can' t correct CML malignant phenotype. Though using CyclinDl antisense- oligodeoxynucleotide (AS-ODN) to inhibit growth of lung cancer osteosarcoma and esophageal cell have been researched, it has not been reported in references to treat CML, and it is the first time using tyrosine kinase inhibitor and CyclinDl AS-ODN to research its inhibition to K562 cell, that can guide treatment of CML.In this assay, K562 cell was incubated with Genistein and /or CyclinDl AS-ODN, then expression of CyclinDl mRNA and hybrid bcr-abl mRNA were examined by RT-PCR, and expression of CDK4 protein x cell-cycle and apoptosis were examined by immunofluorescence ^ flow cytometry and electron-microscope at the same time. We discuss pathogenesis and treatment of CML From different angle of proliferation and cell cycle.The findings were as follows:(1) Genistein and CyclinDl AS-ODN can apparently inhibits growth of K562 cell, and effect rely on dosage, death cell can' t be observed within 72 hours. (2) K562 cells were blocked in G2/M phase by Genistein there was an increase in G2 phase cells, and a decrease in S phase cells; CyclinDl AS-ODN can affect K562 cell-cycle , there was a decrease in S phase cells, and an GO/G1 phase arrest ; K562 cell can be arrested in G2/M phase by Genistein , and in GO/G1 phase by CyclinDl AS-ODN , hence , more decrease of S phase cells and DMA replication can be observed after K562 incubated with the two reagents. (3)Apoptosis of K562 cells can be induced by Genistein , apoptosis-peak can be observed by flow cytometry ,apoptosis cells and apoptotic bodies can be observed by electron-microscope after K562 cells... |
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