【摘要】 目的:研究转化生长因子β1(TGF-β1)作用于NB4细胞后的细胞凋亡情况、细胞周期改变及内源性TGF-β1、P27Kip1、cyclin E及bcl-2 mRNA水平的变化。方法:瑞氏-吉姆萨染色观察凋亡细胞形态学的变化;流式细胞术检测细胞周期和凋亡;半定量RT-PCR技术检测内源性TGF-β1、P27Kip1、cyclin E以及bcl-2的mRNA水平。结果:TGF-β1能抑制NB4细胞的生长,促进NB4细胞的凋亡。5μg/LTGF-β1使NB4细胞阻滞在G1期。外源性TGF-β1浓度<5μg/L时,内源性TGF-β1的mRNA表达上调,外源性TGF-β1浓度为10μg/L时,内源性TGF-β1mRNA表达下调。5μg/LTGF-β1可使P27Kip1表达上调、cyclin E、bcl-2表达下调。结论:TGF-β1可诱导NB4细胞凋亡,引起细胞周期分布异常;外源性TGF-β1可能通过(1)上调内源性TGF-β1,从而使下游因子P27Kip1高表达以诱导NB4细胞凋亡;(2)TGF-β1直接抑制了cyclin E的表达,或者通过调高P27Kip1的表达反馈抑制cyclin E的活性,进而导致细胞周期阻滞;(3)通过下调bcl-2而诱导NB4细胞凋亡。高浓度的外源性TGF-β1可拮抗内源性TGF-β1表达,可能与其导致TGF-β1受体突变,或存在TGF-β1受体靶点过饱和现象有关。更多还原

【Abstract】 AIM:To study the effects of transforming growth factor-β1 (TGF-β1) on cell apoptosis,cell cycle,production of endogenous TGF-β1,expressions of P27Kip1,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-β1,P27Kip1,cyclin E and bcl-2. RESULTS:TGF-β1 significantly restrained the growth and promoted the apoptosis of NB4 cells. The blockage of NB4 cells treated by TGF-β1 at concentration of 5 μg/L was in G1 phase. Endogenous TGF-β1 mRNA expression in NB4 cells was up-regulated when the concentration of exogenous TGF-β1 was <5 μg/L. Meanwhile,the expression of endogenous TGF-β1 mRNA was down-regulated when the concentration of exogenous TGF-β1 was 10 μg/L. After treated with TGF-β1 at concentration of 5 μg/L,P27Kip1 mRNA expression in NB4 cells was up-regulated,cyclin E and bcl-2 were reduced. CONCLUSION:TGF-β1 is able to induce apoptosis and cell cycle distribution abnormally in NB4 cells by (1) Up-regulation of endogenous TGF-β1,so that NB4 cells was induced into apoptosis through consequently high expression of P27Kip1. (2) TGF-β1 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 P27Kip1. (3) Down-regulation of bcl-2 induces apoptosis of NB4 cells.更多还原