Nucleolar and Spindle Associated Protein 1 (NUSAP1) Inhibits Cell Proliferation and Enhances Susceptibility to Epirubicin In Invasive Breast Cancer Cells by Regulating Cyclin D Kinase (CDK1) and DLGAP5 Expression

BACKGROUND: Differentially expressed genes (DEGs) of IBC were selected from the Gene Expression Omnibus (GEO) chip data: GSE21422 and GSE21974. Network analysis of the DEGs and IBC-related genes was performed in STRING database to find the core gene. Thus, this study aimed to determine the role of NUSAP1 in invasive breast cancer (IBC) and to investigate its effect on drug susceptibility to epirubicin (E-ADM). MATERIAL/METHODS: The mRNA expression of NUSAP1 was determined by quantitative polymerase chain reaction (q-PCR). The protein expression was detected by Western blotting. Cell growth and growth cycle were detected by MTT assay and flow cytometry, respectively. Cell migration and invasion were tested by Transwell assay. RESULTS: Through use of gene network analysis, we found that NUSAP1 interacts with IBC-related genes. NUSAP1 presented high expression in IBC tissue samples and MCF-7 cells. NUSAP1 overexpression promoted the growth, migration, and invasion of MCF-7 cells. While NUSAP1 gene silencing downregulated the expression of genes associated with cell cycle progression in G2/M phase, cyclin D kinase (CDK1) and DLGAP5 arrested cells in G2/M phase and significantly inhibited the growth, migration, and invasion of MCF-7 cells. si-NUSAP1 increased the susceptibility of MCF-7 cells to E-ADM-induced apoptosis. CONCLUSIONS: Our study provides evidence that downregulation of NUSAP1 can inhibit the proliferation, migration, and invasion of IBC cells by regulating CDK1 and DLGAP5 expression and enhances the drug susceptibility to E-ADM.