Caspase信号通路在双歧杆菌脂磷壁酸诱导结肠癌细胞凋亡中的作用

Effect of caspase signal pathway on lipoteinchoic acid from Bifidobacterium inducing colon cancer cells apoptosis

目的探讨Caspase信号通路在双歧杆菌脂磷壁酸(LTA)诱导结肠癌细胞凋亡中的作用。方法RT-PCR检测经双歧杆菌LTA处理后,结肠癌Lovo细胞中MyD88和FADD mRNA的表达变化;Annexin V检测经Caspase通用抑制剂(Z-Val-Ala-Asp-FMK)预先处理后,双歧杆菌LTA诱导结肠癌Lovo细胞凋亡率的变化;荧光法检测经双歧杆菌LTA处理后,Lovo细胞中Caspase-8活性的变化。结果经双歧杆菌LTA处理后,Lovo细胞中MyD88的mRNA表达明显升高(P<0.05),而FADD信号分子的mRNA表达无明显变化;双歧杆菌LTA能够增强Lovo细胞中Caspase-8的活性(P<0.05),且其诱导Lovo细胞凋亡的作用能够被Caspase抑制剂所抑制(P<0.05)。结论MyD88信号分子在双歧杆菌LTA诱导Lovo细胞凋亡中可能起着承接上游分子TLRs与下游信号分子FADD的作用;而Caspase信号通路可能是双歧杆菌LTA诱导结肠癌Lovo细胞凋亡的主要信号传导途径。

Objective To explore the effect of Caspase signal pathway on lipoteichoic acid（LTA） from Bifidobac-terium inducing colon cancer cells apoptosis. Methods Lovo cells in colon cancer were treated with bifidobacterial LTA （20 μg/ml） for 24 h and 48 h,respectively. The mRNA expressions of MyDg8 and FADD in Lovo cells were detected by RT-PCR,and Caspase-8 activity in Lovo cells was detected by fluorescent assay. After treated with Caspase inhibitor （Z-Val-Ala-Asp-FMK） for 1h,followed by bifidobacterial LTA （20 μg/ml） for 48 h, the change of the apoptosis rate of Lovo cells was detected by Annexin V-FTTC/PI double marked assay. Results Compared with the control groups, the mRNA expression of MyD88 in Lovo cells increased after treated with bifidobacterial LTA for 48 h（ P 〈0.05 ） ,while mRNA expression of FADD nearly unchanged. The activity of Caspase-8 significantly increased in Lovo cells treated with bifidobacterial LTA. After treated with Caspase inhibitor,the apoptosis rate of Lovo cells by bifidobacterial LTA remarkably decreased（ P 〈 0.05）. Conclusions MyD88 signal molecule is a bridge between upstream molecule TLRs and downstream molecule FADD in the process of LTA of Bifidobacterium inducing Lovo cells apoptosis, and Caspase signal pathway could be the main signal pathway of bifidobacterial LTA inducing Lovo cells apoptosis.