| PostgratuateWang ShaTutorSun BingzhongDepartment of hematology,Xijing Hospital, Xi'an, 710032Chronic myeloid leukemia (CML) is a malignant disorder in hematopoietic stem cell, which is characterized by the abnormal rise of the totle myeloid cells in peripheral blood, the tumefaction of spleen, asthenia and other symptoms. The incidence of CML is 20% of all adult leukemias. About 1/105 of the world population suffer from CML every year. The discovery of the Philadelphia (Ph) chromosome in 1960 as the first consistent chromosomal abnormality associated with a specific type of leukemia was a breakthrough in cancer biology. And the Ph chromosome is the result of a t(9; 22) (q34;qll) reciprocal chromosomal translocation, which in fact creats a chimeric bcr-abl gene,encoding a p210BCR"ABL chimeric protein. p21 OBCR"ABL has deregulated ABL tyrosine kinase activity and is believed as the pathogenetic principle. p210BCR'ABL can abnormally activate several signaling pathway, such as: RAS/MAPK pathway, JAK/STAT pathway, PISKpathway and Myc pathway in direct or indirect way. This abnormal activation can therefore result in an expanded clonal hematopoiesis, altered adhesion properties and inhibition of apoptosis of myeloid cells. CRKL protein as one of the major substracts of p210 kinase probably play a key role in the pathogenesis of CML through its SH2 and-3-SH3 domain (Src homology 2 and 3 domain) recruiting all kinds of signaling moleculars.CRKL gene belongs to CRK gene family. CRK gene family includes v-CRK, c-CRK and CRKL. In 1988, Bruce 3 cloned a new oncogene v-CRK from avian sarcoma virus CT10 and sequenced its genome. V-CRK and other members were later identified as adaptor protein. These proteins have no tyrosine kinase activation, but they can bring in the phophorylation of some proteins in cells infected by CT10 virus, thus the author defined it as CRKL (CT10 regulator of kinase ). CRKL (CRK Like) includes one SH2 and two SH3 domain. Its tyrosine residue 207 can be phophorylated by p210 BCR-ABL md its SH3 domain can bind the ABL onco-protein through the sequence rich in proline protein in ABL. Many experiments have proved that CRKL takes part in the p210 BCR-ABL signaling pathway and maybe as a signaling switch..In order to study the specific role of CRKLin CML, we devised and synthesized CRKL antisense sequences which target agsinst the translation initiation sites (codon 2 to 7) of CRKL mRNA. We select Ph-positive K562 cell line as target cells. After H3-TdR, FCM and RT-PCR, we found that CRKL-ASODN can inhibit the proliferation of K562 cells and induce apoptosis of K562 cells. RT-PCR shows an expression inhibition of CRKL gene. Thus, we proved that CRKL can probably affect the pothagenesis of CML cells. This instructs us that CRKL gene can be a new target in CML therapeutic strategy. Maybe the combination of cytotoxic medicine, inhibitor of tyrosine kinase and CRKL-ASODN could cure patients suffering from CML. |
