Study On Molecular Mechanism Of Nano-TiO₂ Induced Stress Damage In Human Colon Cells

Nano titanium dioxide?TiO₂?is widely used in drug development and design,food additives and packaging materials.The human intestinal tract is exposed to the TiO₂ nanoparticles through the oral cavity.Most nano metal particles can cause cellular inflammation and damage,while the colon area is the site where the intestinal system is most prone to pathology.Studying the damage of TiO₂ nanoparticles on colon cells and its mechanism of action is of great significance for the prevention and treatment of colonic inflammation and carcinogenesis.The purpose of this paper is to study the molecular biocompatibility mechanism of TiO₂nanoparticles and human colon cells.The toxicity of TiO₂ nanoparticles on human colon cancer cells?HCT116?and human normal colon cells?NCM460?was investigated by gene expression profiling techniques and bioinformatics analysis.The molecular mechanism of TiO₂ nanoparticles on the body was explored by gene expression profiling chip technology,which laid a foundation for the establishment of a new method for molecular biocompatibility evaluation of nanoparticles,and provided theoretical basis for the development,design and application of TiO₂nanoparticles.The specific research contents of this paper are as follows:1.The anatase-type TiO₂ were synthesized by hydrothermal method.The effects of TiO₂ on HCT116 cells and NCM460 cells in the concentration range of 3-60?g/mL were detected by MTT,ROS,LDH,cell scratch test and flow cytometry.TiO₂ nanoparticles promoted the proliferation of HCT116 cells at a concentration of 3-6?g/mL,but had no significant effect on NCM460 cells.Both colon cell activities were inhibited and cell migration ability was reduced at a concentration of30-60?g/mL TiO₂ nanoparticles.2.The effects of 3?g/mL and 30?g/mL TiO₂ nanoparticles on the expression of miRNA and mRNA in HCT116 cells were detected.Hierarchical clustering,GO function and Pathway function analysis were performed on differentially expressed miRNAs and mRNAs,respectively.The results showed that differential miRNA and mRNA significantly affected cell metabolism,transcriptional regulation,signal transduction,proliferation,differentiation,apoptosis and other related pathways.The results of the two tests were consistent,confirming the accuracy of the expression profiling results.3.miRNA-378b and miRNA-378g with differential expression were screened for RT-qPCR,and the results were consistent with microRNA expression profiles.miRNA target genes CREB and MAPK1 are important genes in the cAMP pathway and MAPK/ERK pathway,regulating cell growth,differentiation,metabolism and apoptosis.The genes related to c-Jun,c-Fos,P53,Bax and Bcl2 were screened from differentially expressed mRNA.RT-qPCR and Western blot analysis showed that CREB,c-Jun and c-Fos genes up-regulated in HCT116 cells stimulated by TiO₂ nanoparticles,while Bax expression was down-regulated and Bcl2 was up-regulated,protecting cell survival and reduce damage to cells by TiO₂ nanoparticles.However,in NCM460 cells,the differential expression of CREB,c-Jun and c-Fos was not obvious,while the expression of P53 and Bax was up-regulated and the expression of Bcl2 was down-regulated,which promoted apoptosis.