ABSTRACT
AIM:To study the effects of transforming growth factor-β_1 (TGF-β_1) on cell apoptosis,cell cycle,production of endogenous TGF-β_1,expressions of P27~(Kip1),cyclin E and bcl-2 mRNA levels in NB4 cells. METHODS:Apoptotic morphological changes were observed by Wright-Giemsa staining. Cell cycle and apoptosis were detected with flow cytometry. Semiquantitative RT-PCR was used to examine the mRNA levels of endogenous TGF-β_1,P27~(Kip1),cyclin E and bcl-2. RESULTS:TGF-β_1 significantly restrained the growth and promoted the apoptosis of NB4 cells. The blockage of NB4 cells treated by TGF-β_1 at concentration of 5 μg/L was in G1 phase. Endogenous TGF-β_1 mRNA expression in NB4 cells was up-regulated when the concentration of exogenous TGF-β_1 was <5 μg/L. Meanwhile,the expression of endogenous TGF-β_1 mRNA was down-regulated when the concentration of exogenous TGF-β_1 was 10 μg/L. After treated with TGF-β_1 at concentration of 5 μg/L,P27~(Kip1) mRNA expression in NB4 cells was up-regulated,cyclin E and bcl-2 were reduced. CONCLUSION:TGF-β_1 is able to induce apoptosis and cell cycle distribution abnormally in NB4 cells by (1) Up-regulation of endogenous TGF-β_1,so that NB4 cells was induced into apoptosis through consequently high expression of P27~(Kip1). (2) TGF-β_1 may lead to cell cycle arrest by inhibiting the expression of cyclin E directly,or by inhibiting the activity of cyclin E through the increased expression of P27~(Kip1). (3) Down-regulation of bcl-2 induces apoptosis of NB4 cells.
ABSTRACT
<p><b>OBJECTIVE</b>To study the change of WT1 gene expression during human leukemic K562 cell differentiation and apoptosis induced by bufalin.</p><p><b>METHODS</b>Cell viability was determined by trypan blue exclusion, cell differentiation and apoptosis by nitro blue tetrazolium (NBT) reduction test, morphology and flow cytometry, expression of WT1 protein by Western blot analysis, and expression of WT1 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>(1) The cell proliferation was inhibited by bufalin and the IC(50) at 24, 48, 72 h were 0.026, 0.032 and 0.006 micro mol/L, respectively. (2) Bufalin induced K562 cell differentiation towards macrophage/monocyte within concentration from 0.01 to 0.05 micro mol/L and apoptosis at higher than 0.026 micro mol/L. (3) The expression of WT1 protein and mRNA were downregulated by bufalin in the initial stage of differentiation and apoptosis induced by bufalin.</p><p><b>CONCLUSION</b>K562 cell differentiation and apoptosis induced by bufalin might relate to the downregulation of WT1 expression.</p>