The Effects And Mechanisms Of Baicalin On Inducing Leukemic K562 Cells Apoptosis And Growth Inhibition

【Objective】To investigate the effects of Baicalin on proliferation inhibition and apoptosis induction in human chronic myeloid leukemia cell line K562 cells;on related proteins and mRNA expressions; and the role of PI3K/Akt,MAPK/ERK signal pathways in the apoptosis of K562 induced by Baicalin .【Methods】K562 cells were exposed to various dosages of Baicalin. Proliferation inhibition was detected by both MTT assay and clone formation assay.The ability of Bacillin to induce apoptosis of K562 cells was examined by acridine orange/ethidium bromide(AO/EB) double stainingflow cytometry,DNA fragamentation and. TUNEL labeling method .The expression of bcr/abl,Bcl-2,Bax,c-myc and h-TERT mRNA was detected by RT-PCR;protein expressions of P210,phosphorylation of p210,Bcl-2,c-myc,procaspase-3,procaspase-9,Akt,p-Akt,IκB-α,p-IκB-α,p65,p-p65,mTOR,GSK-3β,p-GSK-3β,MAPK(42/44) and p-MAPK(42/44) were detected by Western-blot.【Results】The results showed that Baicalin could remarkably inhibit the K562 cell proliferation, and the IC50 value at 48h of treatment was about 15μmol·L-1.Staining of cells with AO-EB revealed that Baicalin induced nuclear chromatin condensation.Concomitantly,apoptosis was induced in K562 cells,as measurede by detections of TUNEL labeling,Annexin V/PI double staining and DNA fragmentation.These showed that Baicalin induced apoptosis in K562 cells in dose-dependent manner.RT-PCR and/or Western-Blot showed the expression of P210,phosphorylation of p210,Bcl-2,c-myc,procaspase-3,procaspase-9,Akt,p-Akt,IκB-α,p-IκB-α,p65,p-p65,mTOR,p-GSK-3β,MAPK(42/44) and p-MAPK(42/44) in treated K562 cells decreased,but the expressions of Bax and Bad increased,and no change of expression of GSK-3β.【Conclusion】Baicalin could efficiently inhibit cell growth and induce apoptosis in K562 cells, in which down-regulation of bcr/abl,c-myc,Bcl-2/Bax,and h-TERT expressions may involve. PI3K/Akt and MAPK/ERK signal pathways may be involved in apoptosis of K562 cells after treatment with Baicalin.