转化生长因子-β/Smad信号对人横纹肌肉瘤细胞RD生长和凋亡的调控

目的研究TGF-β／Smad信号对人胚胎性横纹肌肉瘤细胞系RD生长和凋亡的调控作用。方法采用小分子RNA干扰(RNAi)技术,以阳离子脂质体为载体,将生物合成的发夹状短链RNA(shRNA)转染RD细胞,封闭Smad4的表达以阻碍内源性TGF-β／Smad信号的转导;采用逆转录一聚合酶链反应(RT-PCR)和Western blot检验shRNA干扰Smad4表达的效果;采用免疫荧光化学,通过激光共聚焦显微镜检测Smad4封闭前后RD细胞中Smad2／3表达位置的变化;应用四甲基偶氮唑盐(MTY)和。H-thymidine摄入实验检测阻碍内源性TGF-β／Smad信号转导和以外源性TGF-β1刺激这2种条件下RD细胞的生长状况;采用流式细胞术和荧光化学染色检测上述2种条件下RD细胞的凋亡情况。结果RNAi技术可有效封闭RD细胞中Smad4 mRNA和蛋白的表达;Smad4的封闭导致Smad2／3由胞质入核明显减少;内源性TGF-β／Smad信号转导受阻不但抑制RD细胞生长,并且诱导凋亡;外源性、较高浓度的TGF-β1可抑制RD细胞生长,但不诱导凋亡。结论TGF-β／Smad信号在一定的浓度范围内精细调控RD细胞的生长和凋亡。

Effects of transforming growth factor-beta/Smad signaling on the growth and apoptosis of human rhabdomyosarcoma cell line RD

OBJECTIVE: To study the effects of TGF-beta/Smad signaling on the growth and apoptosis of human rhabdomyosarcoma cell line RD. METHODS: Biosynthesized short hairpin RNA (shRNA) was transfected into RD cells by cation liposome vector to suppress Smad4 expression. The mRNA and protein expression of Smad4 in RD after shRNA-transfection were examined by RT-PCR and Western blot respectively. Immunofluorescent staining was used to detect the location of Smad2/3 in RD by laser scanning confocal microscopy. The viability of RD cells was examined by MTT method and (3)H-thymidine incorporation assay. The apoptosis of RD was examined by flow cytometry analysis and fluorescent staining. RESULTS: The expression of mRNA and protein of Smad4 in RD were effectively suppressed by shRNA interference. Such suppression effectively interrupted the endogenous TGF-beta/Smad signaling and consequently blocked the translocation of Smad2/3. The interruption of endogenous TGF-beta/Smad signaling not only inhibited the growth of RD but also induced apoptosis of RD. Exogenous TGF-beta1 inhibited the growth of RD but did not influence the apoptosis of RD. CONCLUSION: shRNA interference can effectively interrupt the TGF-beta/Smad signaling by suppressing the expression of Smad4. TGF-beta/Smad signaling subtly regulates the growth and apoptosis of RD.