Abstract: Objective To explore the possible molecular mechanism of miR-1307-3p in promoting proliferation and migration by targeting ISM1 in breast cancer cells. Methods (1) Cancer Genome Atlas (TCGA) database was used to analyze the expression level of miR-1307-3p and its relationship with clinical indicators in breast cancer patients. (2) qPCR, CCK-8 assay, Scratch test and flow cytometry were used to detect the effects of miR-1307-3p over-expression or silence on the expression of miR-1307-3p, cell proliferation, migration and apoptosis in breast cancer MCF-7 cells, respectively. (3) The target gene of mir-1307-3p was predicted by bioinformatics analysis, and verified by double luciferase reporter gene experiment. Results The relative expression levels of miR-1307-3p were significantly up-regulated both in breast cancer cell lines and breast cancer tissues. Overexpression of miR-1307-3p significantly promoted cell proliferation and migration in MCF-7 cells; on the contrary, miR-1307-3p inhibitor significantly inhibited cell migration and induced cell apoptosis. ISM1 may be the target genes of miR-1307-3p. The expression level of ISM1 was significantly lower in breast cancer tissues than that in normal breast tissues, and was significantly correlated with clinical stages. Conclusion MiR- 1307-3p can promote the proliferation and migration of breast cancer cells, which may affect the occurrence and development of breast cancer by targeting ISM1 gene.

Key words: breast neoplasms, microRNAs, cell proliferation, cell movement, miR-1307-3p, Isthmin 1