Identification and clinical validation of NUSAP1 as a novel prognostic biomarker in ovarian cancer

Background Nucleolar and spindle-associated protein 1 (NUSAP1) was shown to be involved in cell cycle regulation in cancer. However, its prognostic value and underlying mechanism in ovarian cancer remain unclear. Methods Oncomine, TCGA, CCLE, and UALCAN databases were used to analyze the expression level of NUSAP1 in ovarian cancer. The Kaplan-Meier plotter database was used to evaluate its prognostic value. The results from these analyses were further validated using immunohistochemical assay. The potential molecular mechanism of NUSAP1 in ovarian cancer was assessed with respect to homologous recombination repair, mismatch repair, and immunology using different databases. Results Database analyses and experimental results demonstrated that NUSAP1 was highly expressed in ovarian cancer, its levels being correlated with the FIGO stage. High NUSAP1 expression was an independent risk factor affecting the prognosis of patients with epithelial ovarian cancer. Moreover, NUSAP1 was associated with cell cycle, DNA replication, homologous recombination, and p53 signaling pathway. A positive correlation was identified between the expression of NUSAP1 and BRCA1/2 in ovarian cancer. In addition, NUSAP1 was associated with the expression of DNA mismatch repair genes and immune cell infiltration. Conclusions NUSAP1 may be a valuable prognostic marker, as well as a novel biomarker for evaluating the response to immunotherapy of patients with ovarian cancer.