This study investigated the role of microRNA(miRNA) in regulating the cytotoxicity of TiO₂ nanoparticles (nano-TiO₂) to RAW264.7 cells. RAW264.7 cells were treated with 0 and 100 μg/ml nano-TiO₂ for 24 h (for miRNA analysis). The differentially expressed miRNAs were detected using Illumina HiSeq™ 2000 sequencing. Through the bio-informatics analysis, miR-350 was found to play an important role in multiple signaling pathways, including MAPK signaling pathway, NF-kappa B signaling pathway and Apoptosis. To characterize the miR-350 function, miR-350 mimic was transfected into RAW264.7 cells for 24 h. MTT and Flow Cytometry were performed to detect cell proliferation, apoptosis and cell cycle (repetition), respectively. QRT-PCR, Western Blot methods and Luciferase assays were applied to detect expression of putative target gene PIK3R3. The results showed that miRNA profiles were differentially dysregulated. The apoptosis rate of miR-350 mimic group was significantly higher than negative control group (p < .05). Cell proliferation and cell cycle had no significant differences between treatment and negative control group. Compared with negative control, the level of protein of PIK3R3 was significantly decreased (p < .05), and the expression of 3′UTR constructs of PIK3R3 was significantly decreased (p < .05) in miR-350 mimic group. The expression of miRNAs was changed after exposed to nano-TiO₂, and biological function and target gene results showed miR-350 may promote RAW264.7 cell apoptosis through the negative regulation of PIK3R3 gene. Our results could provide a basis for further understanding of toxicity and possible mechanisms of nano-TiO₂ exposure.

这项研究调查了microRNA（miRNA）在调节TiO ₂纳米颗粒（nano-TiO ₂）对RAW264.7细胞的细胞毒性中的作用。用0和100μg/ ml纳米TiO ₂处理RAW264.7细胞24小时（用于miRNA分析）。使用Illumina HiSeq™2000测序检测差异表达的miRNA。通过生物信息学分析，发现miR-350在多种信号通路中起重要作用，包括MAPK信号通路，NF-κB信号通路和细胞凋亡。为了表征miR-350的功能，miR-350将模拟物转染到RAW264.7细胞中24小时。进行MTT和流式细胞术分别检测细胞增殖，凋亡和细胞周期（重复）。应用QRT-PCR，Western Blot方法和荧光素酶测定法检测假定的靶基因PIK3R3的表达。结果表明，miRNA谱差异性失调。miR-350模拟组的凋亡率显着高于阴性对照组（p  <.05）。治疗组和阴性对照组之间的细胞增殖和细胞周期无显着差异。与阴性对照相比，PIK3R3的蛋白质水平显着降低（p <0.05），而miR-350模拟组中PIK3R3的3'UTR构建体的表达显着降低（p  <.05）。暴露于纳米TiO ₂后，miRNA的表达发生改变，生物学功能和靶基因结果表明miR-350可能通过PIK3R3基因的负调控促进RAW264.7细胞凋亡。我们的结果可以为进一步了解纳米TiO ₂的毒性和可能的​​机理提供基础。