Mechanism of Autophagic Action of Type I Human Interferon

I型IFN从24小时开始诱导Daudi细胞的自噬，自噬标志物LC 3-II、Atg 5-Atg 12复合物的增加和p62的减少表明了这一点。在HeLa S3、MDA-MB-231、T98 G和A549细胞系中，IFN-α 2c处理后48小时也检测到更高水平的LC 3-II。自噬标记物表达的增加与Daudi细胞中mTORC 1活性的抑制相关。许多信号通路在mTORC 1的调节中发挥作用（例如PI 3 K、AKT）。 用IFN-α 2c与雷帕霉素（mTORC 1抑制剂）或LY 294002（PI 3 K抑制剂）组合处理Daudi和T98 G细胞增加了LC 3-II的水平，表明PI 3 K/AKT/mTORC 1信号通路可能影响Daudi和T98 G细胞中IFN诱导的自噬。通过siRNA敲低实验证实了mTOR和mTOR上游因子在I型IFN诱导的自噬中的作用。使用透射电子显微镜显示自噬体的存在。总之，我们的研究结果证明了一种新的功能，I型干扰素作为诱导剂的自噬在各种癌细胞系。

Type I IFN induces autophagy in Daudi cells starting at 24 h as indicated by an increase of autophagy markers LC3-II, Atg5-Atg12 complexes, and a decrease of p62. Higher levels of LC3-II were also detected 48 h post IFN-alpha2c treatment in HeLa S3, MDA-MB-231, T98G and A549 cell lines. The increase in expression of autophagy markers correlated with inhibition of mTORC1 activity in Daudi cells. Many signaling pathways play a role in regulation of mTORC1 (e.g. PI3K, AKT). Treatment of Daudi and T98G cells with IFN-alpha2c in combination with either rapamycin (mTORC1 inhibitor) or LY294002 (PI3K inhibitor) increased the level of LC3-II, indicating that the PI3K/AKT/mTORC1 signaling pathway may affect IFN-induced autophagy in Daudi and T98G cells. The role of mTOR and factors upstream of mTOR in Type I IFN-induced autophagy was confirmed by siRNA knockdown experiments. The presence of autophagosomes was shown using transmission electron microscopy. In conclusion, our findings demonstrate a novel function of Type I IFN as an inducer of autophagy in a variety of cancer cell lines.