MicroRNAs( miRNAs)are a family of endogenous noncoding small RNA molecules that are approximately 20 nucleotides in length. Aberrant expression or dysfunction of miRNAs and subsequent dysregulation of their target genes might be involved in the occurrence and development of various cancers. Gastric cancer is a leading malignant disease worldwide. Recent studies have shown that some miRNAs are closely associated with the proliferation,migration,invasion, apoptosis and chemosensitivity of gastric cancer cells by regulating their target genes. Advances in study on gastric cancer-related miRNAs,their target genes,and the use of miRNAs-targeted therapy in gastric cancer were reviewed in this article.

Objective To prepare a novel photosensitive nanoparticle and to evaluate its physicochemical properties,and effect on the efficacy of photodynamic therapy.Methods 5,15-dibromo-10,20-diphenylporphine(DBN),tetrafluoroterephthalonitrile(TFN),and the amphiphilic polymer methoxy-polyethylene glycol-distearoylphosphatidylethanolamine(DSPE-MPEG2000,PEG)were dissolved in tetrahydrofuran(THF)by co-precipitation method to prepare novel photosensitive nanoparticles,named DBN/TFN@PEG.The physicochemical properties of DBN/TFN@PEG were characterized.Both novel and conventional nanoparticles were continuously irradiated with a 660 nm laser,and the fluorescence intensity of nanoparticles,representing reactive oxygen species(ROS)production levels,was measured using a fluorescence spectrophotometer at different irradiation times.Tumor cells were co-incubated with the nanoparticles and irradiated with a 660 nm laser.ROS levels within the tumor cells were detected using immunofluorescence,and the ratio of dead to live tumor cells was determined using PI/Calcein-AM staining.Results Prepared DBN/TFN@PEG nanoparticles with hydrated particle size of approximately 107.8 nm were uniformly distributed in the solution.Compared to conventional nanoparticles,the ROS production capacity of DBN/TFN@PEG was significantly higher(P＜0.01).Immunofluorescence results showed that the generation of ROS levels in the tumor cells of DBN/TFN@PEG group were significantly higher than in the conventional nanoparticles group under laser irradiation(P＜0.01).PI/Calcein-AM staining results indicated a significantly higher ratio of dead tumor cells in the DBN/TFN@PEG group compared to the conventional nanoparticle group(P＜0.01).Conclusions DBN/TFN@PEG has stable physicochemical properties and uniform distribution in the solution.As effective photosensitizers,DBN/TFN@PEG can exhibit stronger ability to induce ROS generation in tumor cells,and may enhance the efficacy of photodynamic therapy in cancer.