β-catenin Effected The Tumor-forming Ability Of K562 Cells In Vivo And Effected The Biologic Function Of Primary CML Stem/progenitor Cells In Vitro And In Vivo

In recent years,studies have revealed that Wnt/β-catenin abnormally activated in many kinds of solid tumor and hematologic cancer,and it played some considerable roles in the development or maintainance of tumor.Furthermore,the accumulation ofβ-catenin and increased level ofβ-catenin seemed to be the keypoint of Wnt/β-catenin signaling pathway in cancer.Up-regulation ofβ-catenin caused Granulocyte-Macrophage progenitors(GMP) transforming to leukemic stem cells(LSC) in blast-crisis CML.Studies have also found that the expression level ofβ-catenin often increased in the progression of CML phase.Based on these study backgrounds and our prior work,we targetedβ-catenin and upor down-regulated its expression level,observed the corresponding change of biologic function of CML cells,tried to find some valuable cues for researching the mechanism of CML blast crisis and find some potential pathway to cure advanced CML. Our research work was consisting of two parts:Part One:Extending our prior work,we observed the change of tumor-forming ability of K562 cells in vivo after specific shRNA targetinterferingβ-catenin.Nude mouse hypodermic tumor-forming experiment showed:After interference,the tumor-forming ability of K562 cells was significantly depressed.①Tumor-forming rate:The rate of non-interference group(n=9),control group(which interfered with "null" plasmid,n=8) and interfer group(which interfered with pshRNA-β-catenin plasmid,n=9) was I00%, 87.5%and 0,accordingly,rherate of interference group was much lower than other two groups(P＜0.001).②Tumor-forming curve:First two groups both formed tumor and tumor volume was no difference in the end,however,tumor growed a little more quickly in non-interference group.Interference group formed no tumor.Part Two:Up-or down-regulatedβ-catenin expression level, observed the corresponding change of biologic function of primary CML stem/progenitor cells(CD34+ cells).①Transfected primary CML stem/progenitor cells by means of Nucleofect,transfect-rate was upto 70%.After nucleofected CML-CP stem/progenitor cells withβ-catenin plasmid, -catenin expression level in the cells increased 6.10±2.99 (Range:3.52～12.19) folds as before(P = 0.005).And, nucleofected CML-BC stem/progenitor cells with shRNA-β-catenin plasmid,β-catenin expression level in the cells decreased 8.79±3.05(Range:5.77～13.29) folds as before(P = 0.043).②After nucleofected CML-CP stem/progenitor cells withβ-catenin plasmid,the growth and proliferation ability of cells were enhanced,contrasting to the control group. After nucleofected CML-BC stem/progenitor cells with shRNA-β-catenin plasmid,the growth and proliferation ability of cells were depressed,contrasting to the control group. Nucleofeted CML stem/progenitor cells didn't affect its BCR-ABL transcript level.According to these findings,we think that:①shRNA interference down-regulated the expression ofβ-catenin,it affected the growth and proliferation ability of K562 cell in vitro and also depressed K562 cell form tumor in vivo. Nucleofected CML stem/ progenitor cells with fuctional or interference fragment was an effective way to up-or down-regulateβ-catenin' s level.③Up-regulated -catenin' s level could enhance the growth and proliferation ability of CML-CP stem/ progenitor cells in vitro.④ Down-regulatedβ-catenin' s level would depress the growth and proliferation of CML-BC stem/ progenitor cells in vitro.⑤It needs further experiments to reveal howβ-catenin effect CML stem/ progenitor cells in vivo.Conclusion: -catenin should play an important role in the progression of CML,not just play as a concomitant manifestation.Research targeting atβ-catenin maybe provid some helpful cues for better understanding the mechanism of CML blast crisis and provid some promising approaches to cure advanced CML.